Neurology

In this issue: 

• Limb Loss and Prostheses
• Neurology
  • Traumatic Brain Injury
  • Alzheimer's and Dementia
  • Amyotrophic Lateral Sclerosis (ALS)
  • Parkinson's Disease
  • Migraine and Headache
• Cardiology
• Mental Health
  • Depression
  • Opioid Use Disorder
  • PTSD and Psychedelic Treatments
  • Homelessness
  • Eating Disorders
• Diabetes
• Rheumatoid Arthritis
• Respiratory illnesses
• Women's Health
  • Access to Care
  • Infertility
  • Pregnancy
• HPV and Related Cancers

In this issue: 

• Limb Loss and Prostheses
• Neurology
  • Traumatic Brain Injury
  • Alzheimer's and Dementia
  • Amyotrophic Lateral Sclerosis (ALS)
  • Parkinson's Disease
  • Migraine and Headache
• Cardiology
• Mental Health
  • Depression
  • Opioid Use Disorder
  • PTSD and Psychedelic Treatments
  • Homelessness
  • Eating Disorders
• Diabetes
• Rheumatoid Arthritis
• Respiratory illnesses
• Women's Health
  • Access to Care
  • Infertility
  • Pregnancy
• HPV and Related Cancers

In this issue: 

• Limb Loss and Prostheses
• Neurology
  • Traumatic Brain Injury
  • Alzheimer's and Dementia
  • Amyotrophic Lateral Sclerosis (ALS)
  • Parkinson's Disease
  • Migraine and Headache
• Cardiology
• Mental Health
  • Depression
  • Opioid Use Disorder
  • PTSD and Psychedelic Treatments
  • Homelessness
  • Eating Disorders
• Diabetes
• Rheumatoid Arthritis
• Respiratory illnesses
• Women's Health
  • Access to Care
  • Infertility
  • Pregnancy
• HPV and Related Cancers

Click to view more from Federal Health Care Data Trends 2023.

Click to view more from Federal Health Care Data Trends 2023.

Click to view more from Federal Health Care Data Trends 2023.

I have written before about the COSMOS study and its finding that multivitamins (and chocolate) did not improve brain or cardiovascular health. So I was surprised to read that a “new” study found that vitamins can forestall dementia and age-related cognitive decline.

Upon closer look, the new data are neither new nor convincing, at least to me.

©Graça Victoria/iStockphoto.com

Chocolate and multivitamins for CVD and cancer prevention

The large randomized COSMOS trial was supposed to be the definitive study on chocolate that would establish its heart-health benefits without a doubt. Or, rather, the benefits of a cocoa bean extract in pill form given to healthy, older volunteers. The COSMOS study was negative. Chocolate, or the cocoa bean extract they used, did not reduce cardiovascular events.

And yet for all the prepublication importance attached to COSMOS, it is scarcely mentioned. Had it been positive, rest assured that Mars, the candy bar company that cofunded the research, and other interested parties would have been shouting it from the rooftops. As it is, they’re already spinning it.

Which brings us to the multivitamin component. COSMOS actually had a 2 × 2 design. In other words, there were four groups in this study: chocolate plus multivitamin, chocolate plus placebo, placebo plus multivitamin, and placebo plus placebo. This type of study design allows you to study two different interventions simultaneously, provided that they are independent and do not interact with each other. In addition to the primary cardiovascular endpoint, they also studied a cancer endpoint.

The multivitamin supplement didn’t reduce cardiovascular events either. Nor did it affect cancer outcomes. The main COSMOS study was negative and reinforced what countless other studies have proven: Taking a daily multivitamin does not reduce your risk of having a heart attack or developing cancer.
 

But wait, there’s more: COSMOS-Mind

But no researcher worth his salt studies just one or two endpoints in a study. The participants also underwent neurologic and memory testing. These results were reported separately in the COSMOS-Mind study.

COSMOS-Mind is often described as a separate (or “new”) study. In reality, it included the same participants from the original COSMOS trial and measured yet another primary outcome of cognitive performance on a series of tests administered by telephone. Although there is nothing inherently wrong with studying multiple outcomes in your patient population (after all, that salami isn’t going to slice itself), they cannot all be primary outcomes. Some, by necessity, must be secondary hypothesis–generating outcomes. If you test enough endpoints, multiple hypothesis testing dictates that eventually you will get a positive result simply by chance.

There was a time when the neurocognitive outcomes of COSMOS would have been reported in the same paper as the cardiovascular outcomes, but that time seems to have passed us by. Researchers live or die by the number of their publications, and there is an inherent advantage to squeezing as many publications as possible from the same dataset. Though, to be fair, the journal would probably have asked them to split up the paper as well.

In brief, the cocoa extract again fell short in COSMOS-Mind, but the multivitamin arm did better on the composite cognitive outcome. It was a fairly small difference – a 0.07-point improvement on the z-score at the 3-year mark (the z-score is the mean divided by the standard deviation). Much was also made of the fact that the improvement seemed to vary by prior history of cardiovascular disease (CVD). Those with a history of CVD had a 0.11-point improvement, whereas those without had a 0.06-point improvement. The authors couldn’t offer a definitive explanation for these findings. Any argument that multivitamins improve cardiovascular health and therefore prevent vascular dementia has to contend with the fact that the main COSMOS study didn’t show a cardiovascular benefit for vitamins. Speculation that you are treating nutritional deficiencies is exactly that: speculation.

A more salient question is: What does a 0.07-point improvement on the z-score mean clinically? This study didn’t assess whether a multivitamin supplement prevented dementia or allowed people to live independently for longer. In fairness, that would have been exceptionally difficult to do and would have required a much longer study.

Their one attempt to quantify the cognitive benefit clinically was a calculation about normal age-related decline. Test scores were 0.045 points lower for every 1-year increase in age among participants (their mean age was 73 years). So the authors contend that a 0.07-point increase, or the 0.083-point increase that they found at year 3, corresponds to 1.8 years of age-related decline forestalled. Whether this is an appropriate assumption, I leave for the reader to decide.
 

COSMOS-Web and replication

The results of COSMOS-Mind were seemingly bolstered by the recent publication of COSMOS-Web. Although I’ve seen this study described as having replicated the results of COSMOS-Mind, that description is a bit misleading. This was yet another ancillary COSMOS study; more than half of the 2,262 participants in COSMOS-Mind were also included in COSMOS-Web. Replicating results in the same people isn’t true replication.

The main difference between COSMOS-Mind and COSMOS-Web is that the former used a telephone interview to administer the cognitive tests and the latter used the Internet. They also had different endpoints, with COSMOS-Web looking at immediate recall rather than a global test composite.

COSMOS-Web was a positive study in that patients getting the multivitamin supplement did better on the test for immediate memory recall (remembering a list of 20 words), though they didn’t improve on tests of memory retention, executive function, or novel object recognition (basically a test where subjects have to identify matching geometric patterns and then recall them later). They were able to remember an additional 0.71 word on average, compared with 0.44 word in the placebo group. (For the record, it found no benefit for the cocoa extract).

Everybody does better on memory tests the second time around because practice makes perfect, hence the improvement in the placebo group. This benefit at 1 year did not survive to the end of follow-up at 3 years, in contrast to COSMOS-Mind, where the benefit was not apparent at 1 year and seen only at year 3. A history of cardiovascular disease didn’t seem to affect the results in COSMOS-Web as it did in COSMOS-Mind. As far as replications go, COSMOS-Web has some very non-negligible differences, compared with COSMOS-Mind. This incongruity, especially given the overlap in the patient populations is hard to reconcile. If COSMOS-Web was supposed to assuage any doubts that persisted after COSMOS-Mind, it hasn’t for me.
 

One of these studies is not like the others

Finally, although the COSMOS trial and all its ancillary study analyses suggest a neurocognitive benefit to multivitamin supplementation, it’s not the first study to test the matter. The Age-Related Eye Disease Study looked at vitamin C, vitamin E, beta-carotene, zinc, and copper. There was no benefit on any of the six cognitive tests administered to patients. The Women’s Health Study, the Women’s Antioxidant Cardiovascular Study and PREADViSE have all failed to show any benefit to the various vitamins and minerals they studied. A meta-analysis of 11 trials found no benefit to B vitamins in slowing cognitive aging.

The claim that COSMOS is the “first” study to test the hypothesis hinges on some careful wordplay. Prior studies tested specific vitamins, not a multivitamin. In the discussion of the paper, these other studies are critiqued for being short term. But the Physicians’ Health Study II did in fact study a multivitamin and assessed cognitive performance on average 2.5 years after randomization. It found no benefit. The authors of COSMOS-Web critiqued the 2.5-year wait to perform cognitive testing, saying it would have missed any short-term benefits. Although, given that they simultaneously praised their 3 years of follow-up, the criticism is hard to fully accept or even understand.

Whether follow-up is short or long, uses individual vitamins or a multivitamin, the results excluding COSMOS are uniformly negative. I for one am skeptical that a multivitamin or any individual vitamin can prevent dementia. Same goes for chocolate.

Do enough tests in the same population, and something will rise above the noise just by chance. When you get a positive result in your research, it’s always exciting. But when a slew of studies that came before you are negative, you aren’t groundbreaking. You’re an outlier.

Dr. Labos is a cardiologist at Hôpital Notre-Dame, Montreal. He has disclosed no relevant financial relationships.

A version of this article appeared on Medscape.com.

I have written before about the COSMOS study and its finding that multivitamins (and chocolate) did not improve brain or cardiovascular health. So I was surprised to read that a “new” study found that vitamins can forestall dementia and age-related cognitive decline.

Upon closer look, the new data are neither new nor convincing, at least to me.

©Graça Victoria/iStockphoto.com

Chocolate and multivitamins for CVD and cancer prevention

The large randomized COSMOS trial was supposed to be the definitive study on chocolate that would establish its heart-health benefits without a doubt. Or, rather, the benefits of a cocoa bean extract in pill form given to healthy, older volunteers. The COSMOS study was negative. Chocolate, or the cocoa bean extract they used, did not reduce cardiovascular events.

And yet for all the prepublication importance attached to COSMOS, it is scarcely mentioned. Had it been positive, rest assured that Mars, the candy bar company that cofunded the research, and other interested parties would have been shouting it from the rooftops. As it is, they’re already spinning it.

Which brings us to the multivitamin component. COSMOS actually had a 2 × 2 design. In other words, there were four groups in this study: chocolate plus multivitamin, chocolate plus placebo, placebo plus multivitamin, and placebo plus placebo. This type of study design allows you to study two different interventions simultaneously, provided that they are independent and do not interact with each other. In addition to the primary cardiovascular endpoint, they also studied a cancer endpoint.

The multivitamin supplement didn’t reduce cardiovascular events either. Nor did it affect cancer outcomes. The main COSMOS study was negative and reinforced what countless other studies have proven: Taking a daily multivitamin does not reduce your risk of having a heart attack or developing cancer.
 

But wait, there’s more: COSMOS-Mind

But no researcher worth his salt studies just one or two endpoints in a study. The participants also underwent neurologic and memory testing. These results were reported separately in the COSMOS-Mind study.

COSMOS-Mind is often described as a separate (or “new”) study. In reality, it included the same participants from the original COSMOS trial and measured yet another primary outcome of cognitive performance on a series of tests administered by telephone. Although there is nothing inherently wrong with studying multiple outcomes in your patient population (after all, that salami isn’t going to slice itself), they cannot all be primary outcomes. Some, by necessity, must be secondary hypothesis–generating outcomes. If you test enough endpoints, multiple hypothesis testing dictates that eventually you will get a positive result simply by chance.

There was a time when the neurocognitive outcomes of COSMOS would have been reported in the same paper as the cardiovascular outcomes, but that time seems to have passed us by. Researchers live or die by the number of their publications, and there is an inherent advantage to squeezing as many publications as possible from the same dataset. Though, to be fair, the journal would probably have asked them to split up the paper as well.

In brief, the cocoa extract again fell short in COSMOS-Mind, but the multivitamin arm did better on the composite cognitive outcome. It was a fairly small difference – a 0.07-point improvement on the z-score at the 3-year mark (the z-score is the mean divided by the standard deviation). Much was also made of the fact that the improvement seemed to vary by prior history of cardiovascular disease (CVD). Those with a history of CVD had a 0.11-point improvement, whereas those without had a 0.06-point improvement. The authors couldn’t offer a definitive explanation for these findings. Any argument that multivitamins improve cardiovascular health and therefore prevent vascular dementia has to contend with the fact that the main COSMOS study didn’t show a cardiovascular benefit for vitamins. Speculation that you are treating nutritional deficiencies is exactly that: speculation.

A more salient question is: What does a 0.07-point improvement on the z-score mean clinically? This study didn’t assess whether a multivitamin supplement prevented dementia or allowed people to live independently for longer. In fairness, that would have been exceptionally difficult to do and would have required a much longer study.

Their one attempt to quantify the cognitive benefit clinically was a calculation about normal age-related decline. Test scores were 0.045 points lower for every 1-year increase in age among participants (their mean age was 73 years). So the authors contend that a 0.07-point increase, or the 0.083-point increase that they found at year 3, corresponds to 1.8 years of age-related decline forestalled. Whether this is an appropriate assumption, I leave for the reader to decide.
 

COSMOS-Web and replication

The results of COSMOS-Mind were seemingly bolstered by the recent publication of COSMOS-Web. Although I’ve seen this study described as having replicated the results of COSMOS-Mind, that description is a bit misleading. This was yet another ancillary COSMOS study; more than half of the 2,262 participants in COSMOS-Mind were also included in COSMOS-Web. Replicating results in the same people isn’t true replication.

The main difference between COSMOS-Mind and COSMOS-Web is that the former used a telephone interview to administer the cognitive tests and the latter used the Internet. They also had different endpoints, with COSMOS-Web looking at immediate recall rather than a global test composite.

COSMOS-Web was a positive study in that patients getting the multivitamin supplement did better on the test for immediate memory recall (remembering a list of 20 words), though they didn’t improve on tests of memory retention, executive function, or novel object recognition (basically a test where subjects have to identify matching geometric patterns and then recall them later). They were able to remember an additional 0.71 word on average, compared with 0.44 word in the placebo group. (For the record, it found no benefit for the cocoa extract).

Everybody does better on memory tests the second time around because practice makes perfect, hence the improvement in the placebo group. This benefit at 1 year did not survive to the end of follow-up at 3 years, in contrast to COSMOS-Mind, where the benefit was not apparent at 1 year and seen only at year 3. A history of cardiovascular disease didn’t seem to affect the results in COSMOS-Web as it did in COSMOS-Mind. As far as replications go, COSMOS-Web has some very non-negligible differences, compared with COSMOS-Mind. This incongruity, especially given the overlap in the patient populations is hard to reconcile. If COSMOS-Web was supposed to assuage any doubts that persisted after COSMOS-Mind, it hasn’t for me.
 

One of these studies is not like the others

Finally, although the COSMOS trial and all its ancillary study analyses suggest a neurocognitive benefit to multivitamin supplementation, it’s not the first study to test the matter. The Age-Related Eye Disease Study looked at vitamin C, vitamin E, beta-carotene, zinc, and copper. There was no benefit on any of the six cognitive tests administered to patients. The Women’s Health Study, the Women’s Antioxidant Cardiovascular Study and PREADViSE have all failed to show any benefit to the various vitamins and minerals they studied. A meta-analysis of 11 trials found no benefit to B vitamins in slowing cognitive aging.

The claim that COSMOS is the “first” study to test the hypothesis hinges on some careful wordplay. Prior studies tested specific vitamins, not a multivitamin. In the discussion of the paper, these other studies are critiqued for being short term. But the Physicians’ Health Study II did in fact study a multivitamin and assessed cognitive performance on average 2.5 years after randomization. It found no benefit. The authors of COSMOS-Web critiqued the 2.5-year wait to perform cognitive testing, saying it would have missed any short-term benefits. Although, given that they simultaneously praised their 3 years of follow-up, the criticism is hard to fully accept or even understand.

Whether follow-up is short or long, uses individual vitamins or a multivitamin, the results excluding COSMOS are uniformly negative. I for one am skeptical that a multivitamin or any individual vitamin can prevent dementia. Same goes for chocolate.

Do enough tests in the same population, and something will rise above the noise just by chance. When you get a positive result in your research, it’s always exciting. But when a slew of studies that came before you are negative, you aren’t groundbreaking. You’re an outlier.

Dr. Labos is a cardiologist at Hôpital Notre-Dame, Montreal. He has disclosed no relevant financial relationships.

A version of this article appeared on Medscape.com.

I have written before about the COSMOS study and its finding that multivitamins (and chocolate) did not improve brain or cardiovascular health. So I was surprised to read that a “new” study found that vitamins can forestall dementia and age-related cognitive decline.

Upon closer look, the new data are neither new nor convincing, at least to me.

©Graça Victoria/iStockphoto.com

Chocolate and multivitamins for CVD and cancer prevention

The large randomized COSMOS trial was supposed to be the definitive study on chocolate that would establish its heart-health benefits without a doubt. Or, rather, the benefits of a cocoa bean extract in pill form given to healthy, older volunteers. The COSMOS study was negative. Chocolate, or the cocoa bean extract they used, did not reduce cardiovascular events.

And yet for all the prepublication importance attached to COSMOS, it is scarcely mentioned. Had it been positive, rest assured that Mars, the candy bar company that cofunded the research, and other interested parties would have been shouting it from the rooftops. As it is, they’re already spinning it.

Which brings us to the multivitamin component. COSMOS actually had a 2 × 2 design. In other words, there were four groups in this study: chocolate plus multivitamin, chocolate plus placebo, placebo plus multivitamin, and placebo plus placebo. This type of study design allows you to study two different interventions simultaneously, provided that they are independent and do not interact with each other. In addition to the primary cardiovascular endpoint, they also studied a cancer endpoint.

The multivitamin supplement didn’t reduce cardiovascular events either. Nor did it affect cancer outcomes. The main COSMOS study was negative and reinforced what countless other studies have proven: Taking a daily multivitamin does not reduce your risk of having a heart attack or developing cancer.
 

But wait, there’s more: COSMOS-Mind

But no researcher worth his salt studies just one or two endpoints in a study. The participants also underwent neurologic and memory testing. These results were reported separately in the COSMOS-Mind study.

COSMOS-Mind is often described as a separate (or “new”) study. In reality, it included the same participants from the original COSMOS trial and measured yet another primary outcome of cognitive performance on a series of tests administered by telephone. Although there is nothing inherently wrong with studying multiple outcomes in your patient population (after all, that salami isn’t going to slice itself), they cannot all be primary outcomes. Some, by necessity, must be secondary hypothesis–generating outcomes. If you test enough endpoints, multiple hypothesis testing dictates that eventually you will get a positive result simply by chance.

There was a time when the neurocognitive outcomes of COSMOS would have been reported in the same paper as the cardiovascular outcomes, but that time seems to have passed us by. Researchers live or die by the number of their publications, and there is an inherent advantage to squeezing as many publications as possible from the same dataset. Though, to be fair, the journal would probably have asked them to split up the paper as well.

In brief, the cocoa extract again fell short in COSMOS-Mind, but the multivitamin arm did better on the composite cognitive outcome. It was a fairly small difference – a 0.07-point improvement on the z-score at the 3-year mark (the z-score is the mean divided by the standard deviation). Much was also made of the fact that the improvement seemed to vary by prior history of cardiovascular disease (CVD). Those with a history of CVD had a 0.11-point improvement, whereas those without had a 0.06-point improvement. The authors couldn’t offer a definitive explanation for these findings. Any argument that multivitamins improve cardiovascular health and therefore prevent vascular dementia has to contend with the fact that the main COSMOS study didn’t show a cardiovascular benefit for vitamins. Speculation that you are treating nutritional deficiencies is exactly that: speculation.

A more salient question is: What does a 0.07-point improvement on the z-score mean clinically? This study didn’t assess whether a multivitamin supplement prevented dementia or allowed people to live independently for longer. In fairness, that would have been exceptionally difficult to do and would have required a much longer study.

Their one attempt to quantify the cognitive benefit clinically was a calculation about normal age-related decline. Test scores were 0.045 points lower for every 1-year increase in age among participants (their mean age was 73 years). So the authors contend that a 0.07-point increase, or the 0.083-point increase that they found at year 3, corresponds to 1.8 years of age-related decline forestalled. Whether this is an appropriate assumption, I leave for the reader to decide.
 

COSMOS-Web and replication

The results of COSMOS-Mind were seemingly bolstered by the recent publication of COSMOS-Web. Although I’ve seen this study described as having replicated the results of COSMOS-Mind, that description is a bit misleading. This was yet another ancillary COSMOS study; more than half of the 2,262 participants in COSMOS-Mind were also included in COSMOS-Web. Replicating results in the same people isn’t true replication.

The main difference between COSMOS-Mind and COSMOS-Web is that the former used a telephone interview to administer the cognitive tests and the latter used the Internet. They also had different endpoints, with COSMOS-Web looking at immediate recall rather than a global test composite.

COSMOS-Web was a positive study in that patients getting the multivitamin supplement did better on the test for immediate memory recall (remembering a list of 20 words), though they didn’t improve on tests of memory retention, executive function, or novel object recognition (basically a test where subjects have to identify matching geometric patterns and then recall them later). They were able to remember an additional 0.71 word on average, compared with 0.44 word in the placebo group. (For the record, it found no benefit for the cocoa extract).

Everybody does better on memory tests the second time around because practice makes perfect, hence the improvement in the placebo group. This benefit at 1 year did not survive to the end of follow-up at 3 years, in contrast to COSMOS-Mind, where the benefit was not apparent at 1 year and seen only at year 3. A history of cardiovascular disease didn’t seem to affect the results in COSMOS-Web as it did in COSMOS-Mind. As far as replications go, COSMOS-Web has some very non-negligible differences, compared with COSMOS-Mind. This incongruity, especially given the overlap in the patient populations is hard to reconcile. If COSMOS-Web was supposed to assuage any doubts that persisted after COSMOS-Mind, it hasn’t for me.
 

One of these studies is not like the others

Finally, although the COSMOS trial and all its ancillary study analyses suggest a neurocognitive benefit to multivitamin supplementation, it’s not the first study to test the matter. The Age-Related Eye Disease Study looked at vitamin C, vitamin E, beta-carotene, zinc, and copper. There was no benefit on any of the six cognitive tests administered to patients. The Women’s Health Study, the Women’s Antioxidant Cardiovascular Study and PREADViSE have all failed to show any benefit to the various vitamins and minerals they studied. A meta-analysis of 11 trials found no benefit to B vitamins in slowing cognitive aging.

The claim that COSMOS is the “first” study to test the hypothesis hinges on some careful wordplay. Prior studies tested specific vitamins, not a multivitamin. In the discussion of the paper, these other studies are critiqued for being short term. But the Physicians’ Health Study II did in fact study a multivitamin and assessed cognitive performance on average 2.5 years after randomization. It found no benefit. The authors of COSMOS-Web critiqued the 2.5-year wait to perform cognitive testing, saying it would have missed any short-term benefits. Although, given that they simultaneously praised their 3 years of follow-up, the criticism is hard to fully accept or even understand.

Whether follow-up is short or long, uses individual vitamins or a multivitamin, the results excluding COSMOS are uniformly negative. I for one am skeptical that a multivitamin or any individual vitamin can prevent dementia. Same goes for chocolate.

Do enough tests in the same population, and something will rise above the noise just by chance. When you get a positive result in your research, it’s always exciting. But when a slew of studies that came before you are negative, you aren’t groundbreaking. You’re an outlier.

Dr. Labos is a cardiologist at Hôpital Notre-Dame, Montreal. He has disclosed no relevant financial relationships.

A version of this article appeared on Medscape.com.

Parkinson’s disease (PD) is a neurodegenerative condition diagnosed pathologically by alpha synuclein–containing Lewy bodies and dopaminergic cell loss in the substantia nigra pars compacta of the midbrain. Loss of dopaminergic input to the caudate and putamen disrupts the direct and indirect basal ganglia pathways for motor control and contributes to the motor symptoms of PD.¹ According to the Movement Disorder Society criteria, PD is diagnosed clinically by bradykinesia (slowness of movement) plus resting tremor and/or rigidity in the presence of supportive criteria, such as levodopa responsiveness and hyposmia, and in the absence of exclusion criteria and red flags that would suggest atypical parkinsonism or an alternative diagnosis.²

Although the diagnosis and treatment of PD focus heavily on the motor symptoms, nonmotor symptoms can arise decades before the onset of motor symptoms and continue throughout the lifespan. Nonmotor symptoms affect patients from head (ie, cognition and mood) to toe (ie, striatal toe pain) and multiple organ systems in between, including the olfactory, integumentary, cardiovascular, gastrointestinal, genitourinary, and autonomic nervous systems. Thus, it is not surprising that nonmotor symptoms of PD impact health-related quality of life more substantially than motor symptoms.³ A helpful analogy is to consider the motor symptoms of PD as the tip of the iceberg and the nonmotor symptoms as the larger, submerged portions of the iceberg.⁴

Nonmotor symptoms can negatively impact the treatment of motor symptoms. For example, imagine a patient who is very rigid and dyscoordinated in the arms and legs, which limits their ability to dress and walk. If this patient also suffers from nonmotor symptoms of orthostatic hypotension and psychosis—both of which can be exacerbated by levodopa—dose escalation of levodopa for the rigidity and dyscoordination could be compromised, rendering the patient undertreated and less mobile.

In this review, we focus on identifying and managing nonmotor symptoms of PD that are relevant to psychiatric practice, including mood and motivational disorders, anxiety disorders, psychosis, cognitive disorders, and disorders related to the pharmacologic and surgical treatment of PD (Figure 1).

Mood and motivational disorders

Depression

Depression is a common symptom in PD that can occur in the prodromal period years to decades before the onset of motor symptoms, as well as throughout the disease course.⁵ The prevalence of depression in PD varies from 3% to 90%, depending on the methods of assessment, clinical setting of assessment, motor symptom severity, and other factors; clinically significant depression likely affects approximately 35% to 38% of patients.^5,6 How depression in patients with PD differs from depression in the general population is not entirely understood, but there does seem to be less guilt and suicidal ideation and a substantial component of negative affect, including dysphoria and anxiety.⁷ Practically speaking, depression is treated similarly in PD and general populations, with a few considerations.

Despite limited randomized controlled trials (RCTs) for efficacy specifically in patients with PD, selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) are generally considered first-line treatments. There is also evidence for tricyclic antidepressants (TCAs), but due to potential worsening of orthostatic hypotension and cognition, TCAs may not be a favorable option for certain patients with PD.^8,9 All antidepressants have the potential to worsen tremor. Theoretically, SNRIs, with noradrenergic activity, may be less tolerable than SSRIs in patients with PD. However, worsening tremor generally has not been a clinically significant adverse event reported in PD depression clinical trials, although it was seen in 17% of patients receiving paroxetine and 21% of patients receiving venlafaxine compared to 7% of patients receiving placebo.^9-11 If tremor worsens, mirtazapine could be considered because it has been reported to cause less tremor than SSRIs or TCAs.¹²

Among medications for PD, pramipexole, a dopamine agonist, may have a beneficial effect on depression.¹³ Additionally, some evidence supports rasagiline, a monoamine oxidase type B inhibitor, as an adjunctive medication for depression in PD.¹⁴ Nevertheless, antidepressant medications remain the standard pharmacologic treatment for PD depression.

Continue to: In terms of nonpharmacologic options...

In terms of nonpharmacologic options, cognitive-behavioral therapy (CBT) is likely efficacious, exercise (especially yoga) is likely efficacious, and repetitive transcranial magnetic stimulation may be efficacious.^15,16 While further high-quality trials are needed, these treatments are low-risk and can be considered, especially for patients who cannot tolerate medications.

Apathy

Apathy—a loss of motivation and goal-directed behavior—can occur in up to 30% of patients during the prodromal period of PD, and in up to 70% of patients throughout the disease course.¹⁷ Apathy can coexist with depression, which can make apathy difficult to diagnose.¹⁷ Given the time constraints of a clinic visit, a practical approach would be to first screen for depression and cognitive impairment. If there is continued suspicion of apathy, the Movement Disorder Society-Sponsored Revision of the Unified Parkinson’s Disease Rating Scale part I question (“In the past week have you felt indifferent to doing activities or being with people?”) can be used to screen for apathy, and more detailed scales, such as the Apathy Scale (AS) or Lille Apathy Rating Scale (LARS), could be used if indicated.¹⁸

There are limited high-quality positive trials of apathy-specific treatments in PD. In an RCT of patients with PD who did not have depression or dementia, rivastigmine improved LARS scores compared to placebo.¹⁵ Piribedil, a D2/D3 receptor agonist, improved apathy in patients who underwent subthalamic nucleus deep brain stimulation (STN DBS).¹⁵ Exercise such as individualized physical therapy programs, dance, and Nordic walking as well as mindfulness interventions were shown to significantly reduce apathy scale scores.¹⁹ SSRIs, SNRIs, and rotigotine showed a trend toward reducing AS scores in RCTs.^10,20

Larger, high-quality studies are needed to clarify the treatment of apathy in PD. In the meantime, a reasonable approach is to first treat any comorbid psychiatric or cognitive disorders, since apathy can be associated with these conditions, and to optimize antiparkinsonian medications for motor symptoms, motor fluctuations, and nonmotor fluctuations. Then, the investigational apathy treatments described in this section could be considered on an individual basis.

Anxiety disorders

Anxiety is seen throughout the disease course of PD in approximately 30% to 50% of patients.²¹ It can manifest as generalized anxiety disorder, panic disorder, and other anxiety disorders. There are no high-quality RCTs of pharmacologic treatments of anxiety specifically in patients with PD, except for a negative safety and tolerability study of buspirone in which one-half of patients experienced worsening motor symptoms.^15,22 Thus, the treatment of anxiety in patients with PD is similar to treatments in the general population. SSRIs and SNRIs are typically considered first-line, benzodiazepines are sometimes used with caution (although cognitive adverse effects and fall risk need to be considered), and nonpharma­cologic treatments such as mindfulness yoga, exercise, CBT, and psycho­therapy can be effective.^16,21,23

Continue to: Because there is the lack...

Because there is the lack of evidence-based treatments for anxiety in PD, we highlight 2 PD-specific anxiety disorders: internal tremor, and nonmotor “off” anxiety.

Internal tremor

Internal tremor is a sense of vibration in the axial and/or appendicular muscles that cannot be seen externally by the patient or examiner. It is not yet fully understood if this phenomenon is sensory, anxiety-related, related to subclinical tremor, or the result of a combination of these factors (ie, sensory awareness of a subclinical tremor that triggers or is worsened by anxiety). There is some evidence for subclinical tremor on electromyography, but internal tremor does not respond to antiparkinsonian medications in 70% of patients.²⁴ More electrophysiological research is needed to clarify this phenomenon. Internal tremor has been associated with anxiety in 64% of patients and often improves with anxiolytic therapies.²⁴

Although poorly understood, internal tremor is a documented phenomenon in 33% to 44% of patients with PD, and in some cases, it may be an initial symptom that motivates a patient to seek medical attention for the first time.^24,25 Internal tremor has also been reported in patients with essential tremor and multiple sclerosis.²⁵ Therefore, physicians should be aware of internal tremor because this symptom could herald an underlying neurological disease.

Nonmotor ‘off’ anxiety

Patients with PD are commonly prescribed carbidopa-levodopa, a dopamine precursor, at least 3 times daily. Initially, this medication controls motor symptoms well from 1 dose to the next. However, as the disease progresses, some patients report motor fluctuations in which an individual dose of carbidopa-levodopa may wear off early, take longer than usual to take effect, or not take effect at all. Patients describe these periods as an “off” state in which they do not feel their medications are working. Such motor fluctuations can lead to anxiety and avoidance behaviors, because patients fear being in public at times when the medication does not adequately control their motor symptoms.

In addition to these motor symptom fluctuations and related anxiety, patients can also experience nonmotor symptom fluctuations. A wide variety of nonmotor symptoms, such as mood, cognitive, and behavioral symptoms, have been reported to fluctuate in parallel with motor symptoms.^26,27 One study reported fluctuating restlessness in 39% of patients with PD, excessive worry in 17%, shortness of breath in 13%, excessive sweating and fear in 12%, and palpitations in 10%.²⁷ A patient with fluctuating shortness of breath, sweating, and palpitations (for example) may repeatedly present to the emergency department with a negative cardiac workup and eventually be diagnosed with panic disorder, whereas the patient is truly experiencing nonmotor “off” symptoms. Thus, it is important to be aware of nonmotor fluctuations so this diagnosis can be made and the symptoms appropriately treated. The first step in treating nonmotor fluctuations is to optimize the antiparkinsonian regimen to minimize fluctuations. If “off” anxiety symptoms persist, anxiolytic medications can be prescribed.²¹

Continue to: Psychosis

Psychosis can occur in prodromal and early PD but is most common in advanced PD.²⁸ One study reported that 60% of patients developed hallucinations or delusions after 12 years of follow-up.²⁹ Disease duration, disease severity, dementia, and rapid eye movement sleep behavior disorder are significant risk factors for psychosis in PD.³⁰ Well-formed visual hallucinations are the most common manifestation of psychosis in patients with PD. Auditory hallucinations and delusions are less common. Delusions are usually seen in patients with dementia and are often paranoid delusions, such as of spousal infidelity.³⁰ Sensory hallucinations can occur, but should not be mistaken with formication, a central pain syndrome in PD that can represent a nonmotor “off” symptom that may respond to dopaminergic medication.³¹ Other more mild psychotic symptoms include illusions or misinterpretation of stimuli, false sense of presence, and passage hallucinations of fleeting figures in the peripheral vision.³⁰

The pathophysiology of PD psychosis is not entirely understood but differs from psychosis in other disorders. It can occur in the absence of antiparkinsonian medication exposure and is thought to be a consequence of the underlying disease process of PD involving neurodegeneration in certain brain regions and aberrant neurotransmission of not only dopamine but also serotonin, acetylcholine, and glutamate.³⁰

Figure 2 outlines the management of psychosis in PD. After addressing medical and medication-related causes, it is important to determine if the psychotic symptom is sufficiently bothersome to and/or potentially dangerous for the patient to warrant treatment. If treatment is indicated, pimavanserin and clozapine are efficacious for psychosis in PD without worsening motor symptoms, and quetiapine is possibly efficacious with a low risk of worsening motor symptoms.¹⁵ Other antipsychotics, such as olanzapine, risperidone, and haloperidol, can substantially worsen motor symptoms.¹⁵ Both second-generation antipsychotics and pimavanserin have an FDA black-box warning for a higher risk of all-cause mortality in older patients with dementia; however, because psychosis is associated with early mortality in PD, the risk/benefit ratio should be discussed with the patient and family for shared decision-making.³⁰ If the patient also has dementia, rivastigmine—which is FDA-approved for PD dementia (PDD)—may also improve hallucinations.³²

Cognitive disorders

This section focuses on PD mild cognitive impairment (PD-MCI) and PDD. When a patient with PD reports cognitive concerns, the approach outlined in Figure 3 can be used to diagnose the cognitive disorder. A detailed history, medication review, and physical examination can identify any medical or psychiatric conditions that could affect cognition. The American Academy of Neurology recommends screening for depression, obtaining blood levels of vitamin B12 and thyroid-stimulating hormone, and obtaining a CT or MRI of the brain to rule out reversible causes of dementia.³³ A validated screening test such as the Montreal Cognitive Assessment, which has higher sensitivity for PD-MCI than the Mini-Mental State Examination, is used to identify and quantify cognitive impairment.³⁴ Neuropsychological testing is the gold standard and can be used to confirm and/or better quantify the degree and domains of cognitive impairment.³⁵ Typically, cognitive deficits in PD affect executive function, attention, and/or visuospatial domains more than memory and language early on, and deficits in visuospatial and language domains have the highest sensitivity for predicting progression to PDD.³⁶

Once reversible causes of dementia are addressed or ruled out and cognitive testing is completed, the Movement Disorder Society (MDS) criteria for PD-MCI and PDD summarized in Figure 3 can be used to diagnose the cognitive disorder.^37,38 The MDS criteria for PDD require a diagnosis of PD for ≥1 year prior to the onset of dementia to differentiate PDD from dementia with Lewy bodies (DLB). If the dementia starts within 1 year of the onset of parkinsonism, the diagnosis would be DLB. PDD and DLB are on the spectrum of Lewy body dementia, with the same Lewy body pathology in different temporal and spatial distributions in the brain.³⁸

Continue to: PD-MCI is present in...

PD-MCI is present in approximately 25% of patients.³⁵ PD-MCI does not always progress to dementia but increases the risk of dementia 6-fold. The prevalence of PDD increases with disease duration; it is present in approximately 50% of patients at 10 years and 80% of patients at 20 years of disease.³⁵ Rivastigmine is the only FDA-approved medication to slow progression of PDD. There is insufficient evidence for other acetylcholinesterase inhibitors and memantine.¹⁵ Unfortunately, RCTs of pharmacotherapy for PD-MCI have failed to show efficacy. However, exercise, cognitive rehabilitation, and neuromodulation are being studied. In the meantime, addressing modifiable risk factors (such as vascular risk factors and alcohol consumption) and treating comorbid orthostatic hypotension, obstructive sleep apnea, and depression may improve cognition.^35,39

Treatment-related disorders

Impulse control disorders

Impulse control disorders (ICDs) are an important medication-related consideration in patients with PD. The ICDs seen in PD include pathological gambling, binge eating, excessive shopping, hypersexual behaviors, and dopamine dysregulation syndrome (Table). These disorders are more common in younger patients with a history of impulsive personality traits and addictive behaviors (eg, history of tobacco or alcohol abuse), and are most strongly associated with dopaminergic therapies, particularly the dopamine agonists.^40,41 In the DOMINION study, the odds of ICDs were 2- to 3.5-fold higher in patients taking dopamine agonists.⁴² This is mainly thought to be due to stimulation of D2/D3 receptors in the mesolimbic system.⁴⁰ High doses of levodopa, monoamine oxidase inhibitors, and amantadine are also associated with ICDs.^40-42

The first step in managing ICDs is diagnosing them, which can be difficult because patients often are not forthcoming about these problems due to embarrassment or failure to recognize that the ICD is related to PD medications. If a family member accompanies the patient at the visit, the patient may not want to disclose the amount of money they spend or the extent to which the behavior is a problem. Thus, a screening questionnaire, such as the Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s Disease (QUIP) can be a helpful way for patients to alert the clinician to the issue.⁴¹ Education for the patient and family is crucial before the ICD causes significant financial, health, or relationship problems.

The mainstay of treatment is to reduce or taper off the dopamine agonist or other offending agent while monitoring for worsening motor symptoms and dopamine withdrawal syndrome. If this is unsuccessful, there is very limited evidence for further treatment strategies (Table), including antidepressants, antipsychotics, and mood stabilizers.^40,43,44 There is insufficient evidence for naltrexone based on an RCT that failed to meet its primary endpoint, although naltrexone did significantly reduce QUIP scores.^15,44 There is also insufficient evidence for amantadine, which showed benefit in some studies but was associated with ICDs in the DOMINION study.^15,40,42 In terms of nonpharmacologic treatments, CBT is likely efficacious.^15,40 There are mixed results for STN DBS. Some studies showed improvement in the ICD, due at least in part to dopaminergic medication reduction postoperatively, but this treatment has also been reported to increase impulsivity.^40,45

Deep brain stimulation–related disorders

For patients with PD, the ideal lead location for STN DBS is the dorsolateral aspect of the STN, as this is the motor region of the nucleus. The STN functions in indirect and hyperdirect pathways to put the brake on certain motor programs so only the desired movement can be executed. Its function is clinically demonstrated by patients with STN stroke who develop excessive ballistic movements. Adjacent to the motor region of the STN is a centrally located associative region and a medially located limbic region. Thus, when stimulating the dorsolateral STN, current can spread to those regions as well, and the STN’s ability to put the brake on behavioral and emotional programs can be affected.⁴⁶ Stimulation of the STN has been associated with mania, euphoria, new-onset ICDs, decreased verbal fluency, and executive dysfunction. Depression, apathy, and anxiety can also occur, but more commonly result from rapid withdrawal of antiparkinsonian medications after DBS surgery.^46,47 Therefore, for PD patients with DBS with new or worsening psychiatric or cognitive symptoms, it is important to inquire about any recent programming sessions with neurology as well as recent self-increases in stimulation by the patient using their controller. Collaboration with neurology is important to troubleshoot whether stimulation could be contributing to the patient’s psychiatric or cognitive symptoms.

Continue to: Bottom Line

Mood, anxiety, psychotic, and cognitive symptoms and disorders are common psychiatric manifestations associated with Parkinson’s disease (PD). In addition, patients with PD may experience impulsive control disorders and other symptoms related to treatments they receive for PD. Careful assessment and collaboration with neurology is crucial to alleviating the effects of these conditions.

Related Resources

• Weintraub D, Aarsland D, Chaudhuri KR, et al. The neuropsychiatry of Parkinson’s disease: advances and challenges. Lancet Neurology. 2022;21(1):89-102. doi:10.1016/S1474-4422(21)00330-6
• Goldman JG, Guerra CM. Treatment of nonmotor symptoms associated with Parkinson disease. Neurologic Clinics. 2020;38(2):269-292. doi:10.1016/j.ncl.2019.12.003
• Castrioto A, Lhommee E, Moro E et al. Mood and behavioral effects of subthalamic stimulation in Parkinson’s disease. Lancet Neurology. 2014;13(3):287-305. doi:10.1016/ S1474-4422(13)70294-1

Drug Brand Names

Amantadine • Gocovri
Carbidopa-levodopa • Sinemet
Clozapine • Clozaril
Haloperidol • Haldol
Memantine • Namenda
Mirtazapine • Remeron
Naltrexone • Vivitrol
Olanzapine • Zyprexa
Paroxetine • Paxil
Pimavanserin • Nuplazid
Piribedil • Pronoran
Pramipexole • Mirapex
Quetiapine • Seroquel
Rasagiline • Azilect
Risperidone • Risperdal
Rivastigmine • Exelon
Ropinirole • Requip
Rotigotine • Neupro
Venlafaxine • Effexor
Zonisamide • Zonegran

Parkinson’s disease (PD) is a neurodegenerative condition diagnosed pathologically by alpha synuclein–containing Lewy bodies and dopaminergic cell loss in the substantia nigra pars compacta of the midbrain. Loss of dopaminergic input to the caudate and putamen disrupts the direct and indirect basal ganglia pathways for motor control and contributes to the motor symptoms of PD.¹ According to the Movement Disorder Society criteria, PD is diagnosed clinically by bradykinesia (slowness of movement) plus resting tremor and/or rigidity in the presence of supportive criteria, such as levodopa responsiveness and hyposmia, and in the absence of exclusion criteria and red flags that would suggest atypical parkinsonism or an alternative diagnosis.²

Although the diagnosis and treatment of PD focus heavily on the motor symptoms, nonmotor symptoms can arise decades before the onset of motor symptoms and continue throughout the lifespan. Nonmotor symptoms affect patients from head (ie, cognition and mood) to toe (ie, striatal toe pain) and multiple organ systems in between, including the olfactory, integumentary, cardiovascular, gastrointestinal, genitourinary, and autonomic nervous systems. Thus, it is not surprising that nonmotor symptoms of PD impact health-related quality of life more substantially than motor symptoms.³ A helpful analogy is to consider the motor symptoms of PD as the tip of the iceberg and the nonmotor symptoms as the larger, submerged portions of the iceberg.⁴

Nonmotor symptoms can negatively impact the treatment of motor symptoms. For example, imagine a patient who is very rigid and dyscoordinated in the arms and legs, which limits their ability to dress and walk. If this patient also suffers from nonmotor symptoms of orthostatic hypotension and psychosis—both of which can be exacerbated by levodopa—dose escalation of levodopa for the rigidity and dyscoordination could be compromised, rendering the patient undertreated and less mobile.

In this review, we focus on identifying and managing nonmotor symptoms of PD that are relevant to psychiatric practice, including mood and motivational disorders, anxiety disorders, psychosis, cognitive disorders, and disorders related to the pharmacologic and surgical treatment of PD (Figure 1).

Mood and motivational disorders

Depression

Depression is a common symptom in PD that can occur in the prodromal period years to decades before the onset of motor symptoms, as well as throughout the disease course.⁵ The prevalence of depression in PD varies from 3% to 90%, depending on the methods of assessment, clinical setting of assessment, motor symptom severity, and other factors; clinically significant depression likely affects approximately 35% to 38% of patients.^5,6 How depression in patients with PD differs from depression in the general population is not entirely understood, but there does seem to be less guilt and suicidal ideation and a substantial component of negative affect, including dysphoria and anxiety.⁷ Practically speaking, depression is treated similarly in PD and general populations, with a few considerations.

Despite limited randomized controlled trials (RCTs) for efficacy specifically in patients with PD, selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) are generally considered first-line treatments. There is also evidence for tricyclic antidepressants (TCAs), but due to potential worsening of orthostatic hypotension and cognition, TCAs may not be a favorable option for certain patients with PD.^8,9 All antidepressants have the potential to worsen tremor. Theoretically, SNRIs, with noradrenergic activity, may be less tolerable than SSRIs in patients with PD. However, worsening tremor generally has not been a clinically significant adverse event reported in PD depression clinical trials, although it was seen in 17% of patients receiving paroxetine and 21% of patients receiving venlafaxine compared to 7% of patients receiving placebo.^9-11 If tremor worsens, mirtazapine could be considered because it has been reported to cause less tremor than SSRIs or TCAs.¹²

Among medications for PD, pramipexole, a dopamine agonist, may have a beneficial effect on depression.¹³ Additionally, some evidence supports rasagiline, a monoamine oxidase type B inhibitor, as an adjunctive medication for depression in PD.¹⁴ Nevertheless, antidepressant medications remain the standard pharmacologic treatment for PD depression.

Continue to: In terms of nonpharmacologic options...

In terms of nonpharmacologic options, cognitive-behavioral therapy (CBT) is likely efficacious, exercise (especially yoga) is likely efficacious, and repetitive transcranial magnetic stimulation may be efficacious.^15,16 While further high-quality trials are needed, these treatments are low-risk and can be considered, especially for patients who cannot tolerate medications.

Apathy

Apathy—a loss of motivation and goal-directed behavior—can occur in up to 30% of patients during the prodromal period of PD, and in up to 70% of patients throughout the disease course.¹⁷ Apathy can coexist with depression, which can make apathy difficult to diagnose.¹⁷ Given the time constraints of a clinic visit, a practical approach would be to first screen for depression and cognitive impairment. If there is continued suspicion of apathy, the Movement Disorder Society-Sponsored Revision of the Unified Parkinson’s Disease Rating Scale part I question (“In the past week have you felt indifferent to doing activities or being with people?”) can be used to screen for apathy, and more detailed scales, such as the Apathy Scale (AS) or Lille Apathy Rating Scale (LARS), could be used if indicated.¹⁸

There are limited high-quality positive trials of apathy-specific treatments in PD. In an RCT of patients with PD who did not have depression or dementia, rivastigmine improved LARS scores compared to placebo.¹⁵ Piribedil, a D2/D3 receptor agonist, improved apathy in patients who underwent subthalamic nucleus deep brain stimulation (STN DBS).¹⁵ Exercise such as individualized physical therapy programs, dance, and Nordic walking as well as mindfulness interventions were shown to significantly reduce apathy scale scores.¹⁹ SSRIs, SNRIs, and rotigotine showed a trend toward reducing AS scores in RCTs.^10,20

Larger, high-quality studies are needed to clarify the treatment of apathy in PD. In the meantime, a reasonable approach is to first treat any comorbid psychiatric or cognitive disorders, since apathy can be associated with these conditions, and to optimize antiparkinsonian medications for motor symptoms, motor fluctuations, and nonmotor fluctuations. Then, the investigational apathy treatments described in this section could be considered on an individual basis.

Anxiety disorders

Anxiety is seen throughout the disease course of PD in approximately 30% to 50% of patients.²¹ It can manifest as generalized anxiety disorder, panic disorder, and other anxiety disorders. There are no high-quality RCTs of pharmacologic treatments of anxiety specifically in patients with PD, except for a negative safety and tolerability study of buspirone in which one-half of patients experienced worsening motor symptoms.^15,22 Thus, the treatment of anxiety in patients with PD is similar to treatments in the general population. SSRIs and SNRIs are typically considered first-line, benzodiazepines are sometimes used with caution (although cognitive adverse effects and fall risk need to be considered), and nonpharma­cologic treatments such as mindfulness yoga, exercise, CBT, and psycho­therapy can be effective.^16,21,23

Continue to: Because there is the lack...

Because there is the lack of evidence-based treatments for anxiety in PD, we highlight 2 PD-specific anxiety disorders: internal tremor, and nonmotor “off” anxiety.

Internal tremor

Internal tremor is a sense of vibration in the axial and/or appendicular muscles that cannot be seen externally by the patient or examiner. It is not yet fully understood if this phenomenon is sensory, anxiety-related, related to subclinical tremor, or the result of a combination of these factors (ie, sensory awareness of a subclinical tremor that triggers or is worsened by anxiety). There is some evidence for subclinical tremor on electromyography, but internal tremor does not respond to antiparkinsonian medications in 70% of patients.²⁴ More electrophysiological research is needed to clarify this phenomenon. Internal tremor has been associated with anxiety in 64% of patients and often improves with anxiolytic therapies.²⁴

Although poorly understood, internal tremor is a documented phenomenon in 33% to 44% of patients with PD, and in some cases, it may be an initial symptom that motivates a patient to seek medical attention for the first time.^24,25 Internal tremor has also been reported in patients with essential tremor and multiple sclerosis.²⁵ Therefore, physicians should be aware of internal tremor because this symptom could herald an underlying neurological disease.

Nonmotor ‘off’ anxiety

Patients with PD are commonly prescribed carbidopa-levodopa, a dopamine precursor, at least 3 times daily. Initially, this medication controls motor symptoms well from 1 dose to the next. However, as the disease progresses, some patients report motor fluctuations in which an individual dose of carbidopa-levodopa may wear off early, take longer than usual to take effect, or not take effect at all. Patients describe these periods as an “off” state in which they do not feel their medications are working. Such motor fluctuations can lead to anxiety and avoidance behaviors, because patients fear being in public at times when the medication does not adequately control their motor symptoms.

In addition to these motor symptom fluctuations and related anxiety, patients can also experience nonmotor symptom fluctuations. A wide variety of nonmotor symptoms, such as mood, cognitive, and behavioral symptoms, have been reported to fluctuate in parallel with motor symptoms.^26,27 One study reported fluctuating restlessness in 39% of patients with PD, excessive worry in 17%, shortness of breath in 13%, excessive sweating and fear in 12%, and palpitations in 10%.²⁷ A patient with fluctuating shortness of breath, sweating, and palpitations (for example) may repeatedly present to the emergency department with a negative cardiac workup and eventually be diagnosed with panic disorder, whereas the patient is truly experiencing nonmotor “off” symptoms. Thus, it is important to be aware of nonmotor fluctuations so this diagnosis can be made and the symptoms appropriately treated. The first step in treating nonmotor fluctuations is to optimize the antiparkinsonian regimen to minimize fluctuations. If “off” anxiety symptoms persist, anxiolytic medications can be prescribed.²¹

Continue to: Psychosis

Psychosis can occur in prodromal and early PD but is most common in advanced PD.²⁸ One study reported that 60% of patients developed hallucinations or delusions after 12 years of follow-up.²⁹ Disease duration, disease severity, dementia, and rapid eye movement sleep behavior disorder are significant risk factors for psychosis in PD.³⁰ Well-formed visual hallucinations are the most common manifestation of psychosis in patients with PD. Auditory hallucinations and delusions are less common. Delusions are usually seen in patients with dementia and are often paranoid delusions, such as of spousal infidelity.³⁰ Sensory hallucinations can occur, but should not be mistaken with formication, a central pain syndrome in PD that can represent a nonmotor “off” symptom that may respond to dopaminergic medication.³¹ Other more mild psychotic symptoms include illusions or misinterpretation of stimuli, false sense of presence, and passage hallucinations of fleeting figures in the peripheral vision.³⁰

The pathophysiology of PD psychosis is not entirely understood but differs from psychosis in other disorders. It can occur in the absence of antiparkinsonian medication exposure and is thought to be a consequence of the underlying disease process of PD involving neurodegeneration in certain brain regions and aberrant neurotransmission of not only dopamine but also serotonin, acetylcholine, and glutamate.³⁰

Figure 2 outlines the management of psychosis in PD. After addressing medical and medication-related causes, it is important to determine if the psychotic symptom is sufficiently bothersome to and/or potentially dangerous for the patient to warrant treatment. If treatment is indicated, pimavanserin and clozapine are efficacious for psychosis in PD without worsening motor symptoms, and quetiapine is possibly efficacious with a low risk of worsening motor symptoms.¹⁵ Other antipsychotics, such as olanzapine, risperidone, and haloperidol, can substantially worsen motor symptoms.¹⁵ Both second-generation antipsychotics and pimavanserin have an FDA black-box warning for a higher risk of all-cause mortality in older patients with dementia; however, because psychosis is associated with early mortality in PD, the risk/benefit ratio should be discussed with the patient and family for shared decision-making.³⁰ If the patient also has dementia, rivastigmine—which is FDA-approved for PD dementia (PDD)—may also improve hallucinations.³²

Cognitive disorders

This section focuses on PD mild cognitive impairment (PD-MCI) and PDD. When a patient with PD reports cognitive concerns, the approach outlined in Figure 3 can be used to diagnose the cognitive disorder. A detailed history, medication review, and physical examination can identify any medical or psychiatric conditions that could affect cognition. The American Academy of Neurology recommends screening for depression, obtaining blood levels of vitamin B12 and thyroid-stimulating hormone, and obtaining a CT or MRI of the brain to rule out reversible causes of dementia.³³ A validated screening test such as the Montreal Cognitive Assessment, which has higher sensitivity for PD-MCI than the Mini-Mental State Examination, is used to identify and quantify cognitive impairment.³⁴ Neuropsychological testing is the gold standard and can be used to confirm and/or better quantify the degree and domains of cognitive impairment.³⁵ Typically, cognitive deficits in PD affect executive function, attention, and/or visuospatial domains more than memory and language early on, and deficits in visuospatial and language domains have the highest sensitivity for predicting progression to PDD.³⁶

Once reversible causes of dementia are addressed or ruled out and cognitive testing is completed, the Movement Disorder Society (MDS) criteria for PD-MCI and PDD summarized in Figure 3 can be used to diagnose the cognitive disorder.^37,38 The MDS criteria for PDD require a diagnosis of PD for ≥1 year prior to the onset of dementia to differentiate PDD from dementia with Lewy bodies (DLB). If the dementia starts within 1 year of the onset of parkinsonism, the diagnosis would be DLB. PDD and DLB are on the spectrum of Lewy body dementia, with the same Lewy body pathology in different temporal and spatial distributions in the brain.³⁸

Continue to: PD-MCI is present in...

PD-MCI is present in approximately 25% of patients.³⁵ PD-MCI does not always progress to dementia but increases the risk of dementia 6-fold. The prevalence of PDD increases with disease duration; it is present in approximately 50% of patients at 10 years and 80% of patients at 20 years of disease.³⁵ Rivastigmine is the only FDA-approved medication to slow progression of PDD. There is insufficient evidence for other acetylcholinesterase inhibitors and memantine.¹⁵ Unfortunately, RCTs of pharmacotherapy for PD-MCI have failed to show efficacy. However, exercise, cognitive rehabilitation, and neuromodulation are being studied. In the meantime, addressing modifiable risk factors (such as vascular risk factors and alcohol consumption) and treating comorbid orthostatic hypotension, obstructive sleep apnea, and depression may improve cognition.^35,39

Treatment-related disorders

Impulse control disorders

Impulse control disorders (ICDs) are an important medication-related consideration in patients with PD. The ICDs seen in PD include pathological gambling, binge eating, excessive shopping, hypersexual behaviors, and dopamine dysregulation syndrome (Table). These disorders are more common in younger patients with a history of impulsive personality traits and addictive behaviors (eg, history of tobacco or alcohol abuse), and are most strongly associated with dopaminergic therapies, particularly the dopamine agonists.^40,41 In the DOMINION study, the odds of ICDs were 2- to 3.5-fold higher in patients taking dopamine agonists.⁴² This is mainly thought to be due to stimulation of D2/D3 receptors in the mesolimbic system.⁴⁰ High doses of levodopa, monoamine oxidase inhibitors, and amantadine are also associated with ICDs.^40-42

The first step in managing ICDs is diagnosing them, which can be difficult because patients often are not forthcoming about these problems due to embarrassment or failure to recognize that the ICD is related to PD medications. If a family member accompanies the patient at the visit, the patient may not want to disclose the amount of money they spend or the extent to which the behavior is a problem. Thus, a screening questionnaire, such as the Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s Disease (QUIP) can be a helpful way for patients to alert the clinician to the issue.⁴¹ Education for the patient and family is crucial before the ICD causes significant financial, health, or relationship problems.

The mainstay of treatment is to reduce or taper off the dopamine agonist or other offending agent while monitoring for worsening motor symptoms and dopamine withdrawal syndrome. If this is unsuccessful, there is very limited evidence for further treatment strategies (Table), including antidepressants, antipsychotics, and mood stabilizers.^40,43,44 There is insufficient evidence for naltrexone based on an RCT that failed to meet its primary endpoint, although naltrexone did significantly reduce QUIP scores.^15,44 There is also insufficient evidence for amantadine, which showed benefit in some studies but was associated with ICDs in the DOMINION study.^15,40,42 In terms of nonpharmacologic treatments, CBT is likely efficacious.^15,40 There are mixed results for STN DBS. Some studies showed improvement in the ICD, due at least in part to dopaminergic medication reduction postoperatively, but this treatment has also been reported to increase impulsivity.^40,45

Deep brain stimulation–related disorders

For patients with PD, the ideal lead location for STN DBS is the dorsolateral aspect of the STN, as this is the motor region of the nucleus. The STN functions in indirect and hyperdirect pathways to put the brake on certain motor programs so only the desired movement can be executed. Its function is clinically demonstrated by patients with STN stroke who develop excessive ballistic movements. Adjacent to the motor region of the STN is a centrally located associative region and a medially located limbic region. Thus, when stimulating the dorsolateral STN, current can spread to those regions as well, and the STN’s ability to put the brake on behavioral and emotional programs can be affected.⁴⁶ Stimulation of the STN has been associated with mania, euphoria, new-onset ICDs, decreased verbal fluency, and executive dysfunction. Depression, apathy, and anxiety can also occur, but more commonly result from rapid withdrawal of antiparkinsonian medications after DBS surgery.^46,47 Therefore, for PD patients with DBS with new or worsening psychiatric or cognitive symptoms, it is important to inquire about any recent programming sessions with neurology as well as recent self-increases in stimulation by the patient using their controller. Collaboration with neurology is important to troubleshoot whether stimulation could be contributing to the patient’s psychiatric or cognitive symptoms.

Continue to: Bottom Line

Mood, anxiety, psychotic, and cognitive symptoms and disorders are common psychiatric manifestations associated with Parkinson’s disease (PD). In addition, patients with PD may experience impulsive control disorders and other symptoms related to treatments they receive for PD. Careful assessment and collaboration with neurology is crucial to alleviating the effects of these conditions.

Related Resources

• Weintraub D, Aarsland D, Chaudhuri KR, et al. The neuropsychiatry of Parkinson’s disease: advances and challenges. Lancet Neurology. 2022;21(1):89-102. doi:10.1016/S1474-4422(21)00330-6
• Goldman JG, Guerra CM. Treatment of nonmotor symptoms associated with Parkinson disease. Neurologic Clinics. 2020;38(2):269-292. doi:10.1016/j.ncl.2019.12.003
• Castrioto A, Lhommee E, Moro E et al. Mood and behavioral effects of subthalamic stimulation in Parkinson’s disease. Lancet Neurology. 2014;13(3):287-305. doi:10.1016/ S1474-4422(13)70294-1

Drug Brand Names

Amantadine • Gocovri
Carbidopa-levodopa • Sinemet
Clozapine • Clozaril
Haloperidol • Haldol
Memantine • Namenda
Mirtazapine • Remeron
Naltrexone • Vivitrol
Olanzapine • Zyprexa
Paroxetine • Paxil
Pimavanserin • Nuplazid
Piribedil • Pronoran
Pramipexole • Mirapex
Quetiapine • Seroquel
Rasagiline • Azilect
Risperidone • Risperdal
Rivastigmine • Exelon
Ropinirole • Requip
Rotigotine • Neupro
Venlafaxine • Effexor
Zonisamide • Zonegran

Parkinson’s disease (PD) is a neurodegenerative condition diagnosed pathologically by alpha synuclein–containing Lewy bodies and dopaminergic cell loss in the substantia nigra pars compacta of the midbrain. Loss of dopaminergic input to the caudate and putamen disrupts the direct and indirect basal ganglia pathways for motor control and contributes to the motor symptoms of PD.¹ According to the Movement Disorder Society criteria, PD is diagnosed clinically by bradykinesia (slowness of movement) plus resting tremor and/or rigidity in the presence of supportive criteria, such as levodopa responsiveness and hyposmia, and in the absence of exclusion criteria and red flags that would suggest atypical parkinsonism or an alternative diagnosis.²

Although the diagnosis and treatment of PD focus heavily on the motor symptoms, nonmotor symptoms can arise decades before the onset of motor symptoms and continue throughout the lifespan. Nonmotor symptoms affect patients from head (ie, cognition and mood) to toe (ie, striatal toe pain) and multiple organ systems in between, including the olfactory, integumentary, cardiovascular, gastrointestinal, genitourinary, and autonomic nervous systems. Thus, it is not surprising that nonmotor symptoms of PD impact health-related quality of life more substantially than motor symptoms.³ A helpful analogy is to consider the motor symptoms of PD as the tip of the iceberg and the nonmotor symptoms as the larger, submerged portions of the iceberg.⁴

Nonmotor symptoms can negatively impact the treatment of motor symptoms. For example, imagine a patient who is very rigid and dyscoordinated in the arms and legs, which limits their ability to dress and walk. If this patient also suffers from nonmotor symptoms of orthostatic hypotension and psychosis—both of which can be exacerbated by levodopa—dose escalation of levodopa for the rigidity and dyscoordination could be compromised, rendering the patient undertreated and less mobile.

In this review, we focus on identifying and managing nonmotor symptoms of PD that are relevant to psychiatric practice, including mood and motivational disorders, anxiety disorders, psychosis, cognitive disorders, and disorders related to the pharmacologic and surgical treatment of PD (Figure 1).

Mood and motivational disorders

Depression

Depression is a common symptom in PD that can occur in the prodromal period years to decades before the onset of motor symptoms, as well as throughout the disease course.⁵ The prevalence of depression in PD varies from 3% to 90%, depending on the methods of assessment, clinical setting of assessment, motor symptom severity, and other factors; clinically significant depression likely affects approximately 35% to 38% of patients.^5,6 How depression in patients with PD differs from depression in the general population is not entirely understood, but there does seem to be less guilt and suicidal ideation and a substantial component of negative affect, including dysphoria and anxiety.⁷ Practically speaking, depression is treated similarly in PD and general populations, with a few considerations.

Despite limited randomized controlled trials (RCTs) for efficacy specifically in patients with PD, selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) are generally considered first-line treatments. There is also evidence for tricyclic antidepressants (TCAs), but due to potential worsening of orthostatic hypotension and cognition, TCAs may not be a favorable option for certain patients with PD.^8,9 All antidepressants have the potential to worsen tremor. Theoretically, SNRIs, with noradrenergic activity, may be less tolerable than SSRIs in patients with PD. However, worsening tremor generally has not been a clinically significant adverse event reported in PD depression clinical trials, although it was seen in 17% of patients receiving paroxetine and 21% of patients receiving venlafaxine compared to 7% of patients receiving placebo.^9-11 If tremor worsens, mirtazapine could be considered because it has been reported to cause less tremor than SSRIs or TCAs.¹²

Among medications for PD, pramipexole, a dopamine agonist, may have a beneficial effect on depression.¹³ Additionally, some evidence supports rasagiline, a monoamine oxidase type B inhibitor, as an adjunctive medication for depression in PD.¹⁴ Nevertheless, antidepressant medications remain the standard pharmacologic treatment for PD depression.

Continue to: In terms of nonpharmacologic options...

In terms of nonpharmacologic options, cognitive-behavioral therapy (CBT) is likely efficacious, exercise (especially yoga) is likely efficacious, and repetitive transcranial magnetic stimulation may be efficacious.^15,16 While further high-quality trials are needed, these treatments are low-risk and can be considered, especially for patients who cannot tolerate medications.

Apathy

Apathy—a loss of motivation and goal-directed behavior—can occur in up to 30% of patients during the prodromal period of PD, and in up to 70% of patients throughout the disease course.¹⁷ Apathy can coexist with depression, which can make apathy difficult to diagnose.¹⁷ Given the time constraints of a clinic visit, a practical approach would be to first screen for depression and cognitive impairment. If there is continued suspicion of apathy, the Movement Disorder Society-Sponsored Revision of the Unified Parkinson’s Disease Rating Scale part I question (“In the past week have you felt indifferent to doing activities or being with people?”) can be used to screen for apathy, and more detailed scales, such as the Apathy Scale (AS) or Lille Apathy Rating Scale (LARS), could be used if indicated.¹⁸

There are limited high-quality positive trials of apathy-specific treatments in PD. In an RCT of patients with PD who did not have depression or dementia, rivastigmine improved LARS scores compared to placebo.¹⁵ Piribedil, a D2/D3 receptor agonist, improved apathy in patients who underwent subthalamic nucleus deep brain stimulation (STN DBS).¹⁵ Exercise such as individualized physical therapy programs, dance, and Nordic walking as well as mindfulness interventions were shown to significantly reduce apathy scale scores.¹⁹ SSRIs, SNRIs, and rotigotine showed a trend toward reducing AS scores in RCTs.^10,20

Larger, high-quality studies are needed to clarify the treatment of apathy in PD. In the meantime, a reasonable approach is to first treat any comorbid psychiatric or cognitive disorders, since apathy can be associated with these conditions, and to optimize antiparkinsonian medications for motor symptoms, motor fluctuations, and nonmotor fluctuations. Then, the investigational apathy treatments described in this section could be considered on an individual basis.

Anxiety disorders

Anxiety is seen throughout the disease course of PD in approximately 30% to 50% of patients.²¹ It can manifest as generalized anxiety disorder, panic disorder, and other anxiety disorders. There are no high-quality RCTs of pharmacologic treatments of anxiety specifically in patients with PD, except for a negative safety and tolerability study of buspirone in which one-half of patients experienced worsening motor symptoms.^15,22 Thus, the treatment of anxiety in patients with PD is similar to treatments in the general population. SSRIs and SNRIs are typically considered first-line, benzodiazepines are sometimes used with caution (although cognitive adverse effects and fall risk need to be considered), and nonpharma­cologic treatments such as mindfulness yoga, exercise, CBT, and psycho­therapy can be effective.^16,21,23

Continue to: Because there is the lack...

Because there is the lack of evidence-based treatments for anxiety in PD, we highlight 2 PD-specific anxiety disorders: internal tremor, and nonmotor “off” anxiety.

Internal tremor

Internal tremor is a sense of vibration in the axial and/or appendicular muscles that cannot be seen externally by the patient or examiner. It is not yet fully understood if this phenomenon is sensory, anxiety-related, related to subclinical tremor, or the result of a combination of these factors (ie, sensory awareness of a subclinical tremor that triggers or is worsened by anxiety). There is some evidence for subclinical tremor on electromyography, but internal tremor does not respond to antiparkinsonian medications in 70% of patients.²⁴ More electrophysiological research is needed to clarify this phenomenon. Internal tremor has been associated with anxiety in 64% of patients and often improves with anxiolytic therapies.²⁴

Although poorly understood, internal tremor is a documented phenomenon in 33% to 44% of patients with PD, and in some cases, it may be an initial symptom that motivates a patient to seek medical attention for the first time.^24,25 Internal tremor has also been reported in patients with essential tremor and multiple sclerosis.²⁵ Therefore, physicians should be aware of internal tremor because this symptom could herald an underlying neurological disease.

Nonmotor ‘off’ anxiety

Patients with PD are commonly prescribed carbidopa-levodopa, a dopamine precursor, at least 3 times daily. Initially, this medication controls motor symptoms well from 1 dose to the next. However, as the disease progresses, some patients report motor fluctuations in which an individual dose of carbidopa-levodopa may wear off early, take longer than usual to take effect, or not take effect at all. Patients describe these periods as an “off” state in which they do not feel their medications are working. Such motor fluctuations can lead to anxiety and avoidance behaviors, because patients fear being in public at times when the medication does not adequately control their motor symptoms.

In addition to these motor symptom fluctuations and related anxiety, patients can also experience nonmotor symptom fluctuations. A wide variety of nonmotor symptoms, such as mood, cognitive, and behavioral symptoms, have been reported to fluctuate in parallel with motor symptoms.^26,27 One study reported fluctuating restlessness in 39% of patients with PD, excessive worry in 17%, shortness of breath in 13%, excessive sweating and fear in 12%, and palpitations in 10%.²⁷ A patient with fluctuating shortness of breath, sweating, and palpitations (for example) may repeatedly present to the emergency department with a negative cardiac workup and eventually be diagnosed with panic disorder, whereas the patient is truly experiencing nonmotor “off” symptoms. Thus, it is important to be aware of nonmotor fluctuations so this diagnosis can be made and the symptoms appropriately treated. The first step in treating nonmotor fluctuations is to optimize the antiparkinsonian regimen to minimize fluctuations. If “off” anxiety symptoms persist, anxiolytic medications can be prescribed.²¹

Continue to: Psychosis

Psychosis can occur in prodromal and early PD but is most common in advanced PD.²⁸ One study reported that 60% of patients developed hallucinations or delusions after 12 years of follow-up.²⁹ Disease duration, disease severity, dementia, and rapid eye movement sleep behavior disorder are significant risk factors for psychosis in PD.³⁰ Well-formed visual hallucinations are the most common manifestation of psychosis in patients with PD. Auditory hallucinations and delusions are less common. Delusions are usually seen in patients with dementia and are often paranoid delusions, such as of spousal infidelity.³⁰ Sensory hallucinations can occur, but should not be mistaken with formication, a central pain syndrome in PD that can represent a nonmotor “off” symptom that may respond to dopaminergic medication.³¹ Other more mild psychotic symptoms include illusions or misinterpretation of stimuli, false sense of presence, and passage hallucinations of fleeting figures in the peripheral vision.³⁰

The pathophysiology of PD psychosis is not entirely understood but differs from psychosis in other disorders. It can occur in the absence of antiparkinsonian medication exposure and is thought to be a consequence of the underlying disease process of PD involving neurodegeneration in certain brain regions and aberrant neurotransmission of not only dopamine but also serotonin, acetylcholine, and glutamate.³⁰

Figure 2 outlines the management of psychosis in PD. After addressing medical and medication-related causes, it is important to determine if the psychotic symptom is sufficiently bothersome to and/or potentially dangerous for the patient to warrant treatment. If treatment is indicated, pimavanserin and clozapine are efficacious for psychosis in PD without worsening motor symptoms, and quetiapine is possibly efficacious with a low risk of worsening motor symptoms.¹⁵ Other antipsychotics, such as olanzapine, risperidone, and haloperidol, can substantially worsen motor symptoms.¹⁵ Both second-generation antipsychotics and pimavanserin have an FDA black-box warning for a higher risk of all-cause mortality in older patients with dementia; however, because psychosis is associated with early mortality in PD, the risk/benefit ratio should be discussed with the patient and family for shared decision-making.³⁰ If the patient also has dementia, rivastigmine—which is FDA-approved for PD dementia (PDD)—may also improve hallucinations.³²

Cognitive disorders

This section focuses on PD mild cognitive impairment (PD-MCI) and PDD. When a patient with PD reports cognitive concerns, the approach outlined in Figure 3 can be used to diagnose the cognitive disorder. A detailed history, medication review, and physical examination can identify any medical or psychiatric conditions that could affect cognition. The American Academy of Neurology recommends screening for depression, obtaining blood levels of vitamin B12 and thyroid-stimulating hormone, and obtaining a CT or MRI of the brain to rule out reversible causes of dementia.³³ A validated screening test such as the Montreal Cognitive Assessment, which has higher sensitivity for PD-MCI than the Mini-Mental State Examination, is used to identify and quantify cognitive impairment.³⁴ Neuropsychological testing is the gold standard and can be used to confirm and/or better quantify the degree and domains of cognitive impairment.³⁵ Typically, cognitive deficits in PD affect executive function, attention, and/or visuospatial domains more than memory and language early on, and deficits in visuospatial and language domains have the highest sensitivity for predicting progression to PDD.³⁶

Once reversible causes of dementia are addressed or ruled out and cognitive testing is completed, the Movement Disorder Society (MDS) criteria for PD-MCI and PDD summarized in Figure 3 can be used to diagnose the cognitive disorder.^37,38 The MDS criteria for PDD require a diagnosis of PD for ≥1 year prior to the onset of dementia to differentiate PDD from dementia with Lewy bodies (DLB). If the dementia starts within 1 year of the onset of parkinsonism, the diagnosis would be DLB. PDD and DLB are on the spectrum of Lewy body dementia, with the same Lewy body pathology in different temporal and spatial distributions in the brain.³⁸

Continue to: PD-MCI is present in...

PD-MCI is present in approximately 25% of patients.³⁵ PD-MCI does not always progress to dementia but increases the risk of dementia 6-fold. The prevalence of PDD increases with disease duration; it is present in approximately 50% of patients at 10 years and 80% of patients at 20 years of disease.³⁵ Rivastigmine is the only FDA-approved medication to slow progression of PDD. There is insufficient evidence for other acetylcholinesterase inhibitors and memantine.¹⁵ Unfortunately, RCTs of pharmacotherapy for PD-MCI have failed to show efficacy. However, exercise, cognitive rehabilitation, and neuromodulation are being studied. In the meantime, addressing modifiable risk factors (such as vascular risk factors and alcohol consumption) and treating comorbid orthostatic hypotension, obstructive sleep apnea, and depression may improve cognition.^35,39

Treatment-related disorders

Impulse control disorders

Impulse control disorders (ICDs) are an important medication-related consideration in patients with PD. The ICDs seen in PD include pathological gambling, binge eating, excessive shopping, hypersexual behaviors, and dopamine dysregulation syndrome (Table). These disorders are more common in younger patients with a history of impulsive personality traits and addictive behaviors (eg, history of tobacco or alcohol abuse), and are most strongly associated with dopaminergic therapies, particularly the dopamine agonists.^40,41 In the DOMINION study, the odds of ICDs were 2- to 3.5-fold higher in patients taking dopamine agonists.⁴² This is mainly thought to be due to stimulation of D2/D3 receptors in the mesolimbic system.⁴⁰ High doses of levodopa, monoamine oxidase inhibitors, and amantadine are also associated with ICDs.^40-42

The first step in managing ICDs is diagnosing them, which can be difficult because patients often are not forthcoming about these problems due to embarrassment or failure to recognize that the ICD is related to PD medications. If a family member accompanies the patient at the visit, the patient may not want to disclose the amount of money they spend or the extent to which the behavior is a problem. Thus, a screening questionnaire, such as the Questionnaire for Impulsive-Compulsive Disorders in Parkinson’s Disease (QUIP) can be a helpful way for patients to alert the clinician to the issue.⁴¹ Education for the patient and family is crucial before the ICD causes significant financial, health, or relationship problems.

The mainstay of treatment is to reduce or taper off the dopamine agonist or other offending agent while monitoring for worsening motor symptoms and dopamine withdrawal syndrome. If this is unsuccessful, there is very limited evidence for further treatment strategies (Table), including antidepressants, antipsychotics, and mood stabilizers.^40,43,44 There is insufficient evidence for naltrexone based on an RCT that failed to meet its primary endpoint, although naltrexone did significantly reduce QUIP scores.^15,44 There is also insufficient evidence for amantadine, which showed benefit in some studies but was associated with ICDs in the DOMINION study.^15,40,42 In terms of nonpharmacologic treatments, CBT is likely efficacious.^15,40 There are mixed results for STN DBS. Some studies showed improvement in the ICD, due at least in part to dopaminergic medication reduction postoperatively, but this treatment has also been reported to increase impulsivity.^40,45

Deep brain stimulation–related disorders

For patients with PD, the ideal lead location for STN DBS is the dorsolateral aspect of the STN, as this is the motor region of the nucleus. The STN functions in indirect and hyperdirect pathways to put the brake on certain motor programs so only the desired movement can be executed. Its function is clinically demonstrated by patients with STN stroke who develop excessive ballistic movements. Adjacent to the motor region of the STN is a centrally located associative region and a medially located limbic region. Thus, when stimulating the dorsolateral STN, current can spread to those regions as well, and the STN’s ability to put the brake on behavioral and emotional programs can be affected.⁴⁶ Stimulation of the STN has been associated with mania, euphoria, new-onset ICDs, decreased verbal fluency, and executive dysfunction. Depression, apathy, and anxiety can also occur, but more commonly result from rapid withdrawal of antiparkinsonian medications after DBS surgery.^46,47 Therefore, for PD patients with DBS with new or worsening psychiatric or cognitive symptoms, it is important to inquire about any recent programming sessions with neurology as well as recent self-increases in stimulation by the patient using their controller. Collaboration with neurology is important to troubleshoot whether stimulation could be contributing to the patient’s psychiatric or cognitive symptoms.

Continue to: Bottom Line

Mood, anxiety, psychotic, and cognitive symptoms and disorders are common psychiatric manifestations associated with Parkinson’s disease (PD). In addition, patients with PD may experience impulsive control disorders and other symptoms related to treatments they receive for PD. Careful assessment and collaboration with neurology is crucial to alleviating the effects of these conditions.

Related Resources

• Weintraub D, Aarsland D, Chaudhuri KR, et al. The neuropsychiatry of Parkinson’s disease: advances and challenges. Lancet Neurology. 2022;21(1):89-102. doi:10.1016/S1474-4422(21)00330-6
• Goldman JG, Guerra CM. Treatment of nonmotor symptoms associated with Parkinson disease. Neurologic Clinics. 2020;38(2):269-292. doi:10.1016/j.ncl.2019.12.003
• Castrioto A, Lhommee E, Moro E et al. Mood and behavioral effects of subthalamic stimulation in Parkinson’s disease. Lancet Neurology. 2014;13(3):287-305. doi:10.1016/ S1474-4422(13)70294-1

Drug Brand Names

Amantadine • Gocovri
Carbidopa-levodopa • Sinemet
Clozapine • Clozaril
Haloperidol • Haldol
Memantine • Namenda
Mirtazapine • Remeron
Naltrexone • Vivitrol
Olanzapine • Zyprexa
Paroxetine • Paxil
Pimavanserin • Nuplazid
Piribedil • Pronoran
Pramipexole • Mirapex
Quetiapine • Seroquel
Rasagiline • Azilect
Risperidone • Risperdal
Rivastigmine • Exelon
Ropinirole • Requip
Rotigotine • Neupro
Venlafaxine • Effexor
Zonisamide • Zonegran

For most symptomatic patients with atherosclerotic occlusion of the internal carotid artery (ICA) or middle cerebral artery (MCA), adding extracranial-intracranial (EC-IC) bypass surgery to medical therapy did not reduce stroke or death in comparison with medical therapy alone in the latest randomized trial comparing the two interventions.

However, subgroup analyses suggest a potential benefit of surgery for certain patients, such as those with MCA vs. ICA occlusion, mean transit time greater than 6 seconds, or regional blood flow of 0.8 or less.

“We were disappointed by the results,” Liqun Jiao, MD, of the National Center for Neurological Disorders in Beijing, told this news organization. “We were expecting to demonstrate a benefit from EC-IC bypass surgery over medical treatment alone in symptomatic patients with ICA or MCA occlusion and hemodynamic insufficiency, per our original hypothesis.”

Although the study showed improved efficacy and safety for the surgical procedure, he said, “The progress of medical treatment is even better.”

The study was published online in JAMA.
 

Subgroup analyses promising

Previous randomized clinical trials, including the EC/IC Bypass Study and the Carotid Occlusion Surgery Study (COSS), showed no benefit in stroke prevention for patients with atherosclerotic occlusion of the ICA or MCA.

However, in light of improvements over the years in surgical techniques and patient selection, the authors conducted the Carotid and Middle Cerebral Artery Occlusion Surgery Study (CMOSS), a multicenter, randomized, open-label trial comparing EC-IC bypass surgery plus medical therapy, consisting of antiplatelet therapy and control of stroke risk factors, with medical therapy alone in symptomatic patients with ICA or MCA occlusion and hemodynamic insufficiency, with refined patient and operator selection.

A total of 324 patients (median age, 52.7 years; 79% men) in 13 centers in China were included; 309 patients (95%) completed the study.

The primary outcome was a composite of stroke or death within 30 days or ipsilateral ischemic stroke beyond 30 days through 2 years after randomization.

Secondary outcomes included, among others, any stroke or death within 2 years and fatal stroke within 2 years.

No significant difference was found for the primary outcome between the surgical group (8.6%) and the medical group (12.3%).

The 30-day risk of stroke or death was 6.2% in the surgery group, versus 1.8% (3/163) for the medical group. The risk of ipsilateral ischemic stroke beyond 30 days through 2 years was 2%, versus 10.3% – nonsignificant differences.

Furthermore, none of the prespecified secondary endpoints showed a significant difference, including any stroke or death within 2 years (9.9% vs. 15.3%; hazard ratio, 0.69) and fatal stroke within 2 years (2% vs. none).

Despite the findings, “We are encouraged by the subgroup analysis and the trend of long-term outcomes,” Dr. Jiao said. “We will continue to finish 5-10 years of follow-up to see whether the benefit of bypass surgery can be identified.”

The team has also launched the CMOSS-2 trial with a refined study design based on the results of subgroup analysis of the CMOSS study.

CMOSS-2 is recruiting patients with symptomatic chronic occlusion of the MCA and severe hemodynamic insufficiency in 13 sites in China. The primary outcome is ischemic stroke in the territory of the target artery within 24 months after randomization.
 

Can’t exclude benefit

Thomas Jeerakathil, MD, a professor at the University of Alberta and Northern Stroke Lead, Cardiovascular and Stroke Strategic Clinical Network, Alberta Health Services, Edmonton, commented on the study for this news organization. Like the authors, he said, “I don’t consider this study to definitively exclude the benefit of EC/IC bypass. More studies are required.”

Dr. Jeerakathil would like to see a study of a higher-risk group based on both clinical and hemodynamic blood flow criteria. In the current study, he said, “The trial group overall may not have been at high enough stroke risk to justify the up-front risks of the EC-IC bypass procedure.”

In addition, “The analysis method of Cox proportional hazards regression for the primary outcome did not fit the data when the perioperative period was combined with the period beyond 30 days,” he noted. “The researchers were open about this and did pivot and included a post hoc relative risk-based analysis, but the validity of their primary analysis is questionable.”

Furthermore, the study was “somewhat underpowered with a relatively small sample size and had the potential to miss clinically significant differences between groups,” he said. “It would be good to see a longer follow-up period of at least 5 years added to this trial and used in future trials, rather than 2 years.”

“Lastly,” he said, “it’s difficult to ignore the reduction in recurrent stroke events over the 30-day to 2-year time period associated with EC-IC bypass (from 10.3% down to 2%). This reduction alone shows the procedure has some potential to prevent stroke and would argue for more trials.”

EC-IC could be considered for patients who have failed other medical therapies and have more substantial evidence of compromised blood flow to the brain than those in the CMOSS trial, he noted, as many of these patients have few other options. “In our center and many other centers, the approach to EC-IC bypass is probably much more selective than used in the trial.”

Dr. Jeerakathil concluded, “Clinicians should be cautious about offering the procedure to patients with just mildly delayed blood flow in the hemisphere affected by the occluded artery and those who have not yet failed maximal medical therapy.”

But Seemant Chaturvedi, MD, and J. Marc Simard, MD, PhD, both of the University of Maryland, Baltimore, are not as optimistic about the potential for EC-IC.

Writing in a related editorial, they conclude that the results with EC-IC bypass surgery in randomized trials “remain unimpressive. Until a better understanding of the unique hemodynamic features of the brain is achieved, it will be difficult for neurosurgeons to continue offering this procedure to patients with ICA or MCA occlusion. Intensive, multifaceted medical therapy remains the first-line treatment for [these] patients.”

The study was supported by a research grant from the National Health Commission of the People’s Republic of China. Dr. Jiao, Dr. Jeerakathil, Dr. Chaturvedi, and Dr. Simard reported no conflicts of interest.

A version of this article first appeared on Medscape.com.

For most symptomatic patients with atherosclerotic occlusion of the internal carotid artery (ICA) or middle cerebral artery (MCA), adding extracranial-intracranial (EC-IC) bypass surgery to medical therapy did not reduce stroke or death in comparison with medical therapy alone in the latest randomized trial comparing the two interventions.

However, subgroup analyses suggest a potential benefit of surgery for certain patients, such as those with MCA vs. ICA occlusion, mean transit time greater than 6 seconds, or regional blood flow of 0.8 or less.

“We were disappointed by the results,” Liqun Jiao, MD, of the National Center for Neurological Disorders in Beijing, told this news organization. “We were expecting to demonstrate a benefit from EC-IC bypass surgery over medical treatment alone in symptomatic patients with ICA or MCA occlusion and hemodynamic insufficiency, per our original hypothesis.”

Although the study showed improved efficacy and safety for the surgical procedure, he said, “The progress of medical treatment is even better.”

The study was published online in JAMA.
 

Subgroup analyses promising

Previous randomized clinical trials, including the EC/IC Bypass Study and the Carotid Occlusion Surgery Study (COSS), showed no benefit in stroke prevention for patients with atherosclerotic occlusion of the ICA or MCA.

However, in light of improvements over the years in surgical techniques and patient selection, the authors conducted the Carotid and Middle Cerebral Artery Occlusion Surgery Study (CMOSS), a multicenter, randomized, open-label trial comparing EC-IC bypass surgery plus medical therapy, consisting of antiplatelet therapy and control of stroke risk factors, with medical therapy alone in symptomatic patients with ICA or MCA occlusion and hemodynamic insufficiency, with refined patient and operator selection.

A total of 324 patients (median age, 52.7 years; 79% men) in 13 centers in China were included; 309 patients (95%) completed the study.

The primary outcome was a composite of stroke or death within 30 days or ipsilateral ischemic stroke beyond 30 days through 2 years after randomization.

Secondary outcomes included, among others, any stroke or death within 2 years and fatal stroke within 2 years.

No significant difference was found for the primary outcome between the surgical group (8.6%) and the medical group (12.3%).

The 30-day risk of stroke or death was 6.2% in the surgery group, versus 1.8% (3/163) for the medical group. The risk of ipsilateral ischemic stroke beyond 30 days through 2 years was 2%, versus 10.3% – nonsignificant differences.

Furthermore, none of the prespecified secondary endpoints showed a significant difference, including any stroke or death within 2 years (9.9% vs. 15.3%; hazard ratio, 0.69) and fatal stroke within 2 years (2% vs. none).

Despite the findings, “We are encouraged by the subgroup analysis and the trend of long-term outcomes,” Dr. Jiao said. “We will continue to finish 5-10 years of follow-up to see whether the benefit of bypass surgery can be identified.”

The team has also launched the CMOSS-2 trial with a refined study design based on the results of subgroup analysis of the CMOSS study.

CMOSS-2 is recruiting patients with symptomatic chronic occlusion of the MCA and severe hemodynamic insufficiency in 13 sites in China. The primary outcome is ischemic stroke in the territory of the target artery within 24 months after randomization.
 

Can’t exclude benefit

Thomas Jeerakathil, MD, a professor at the University of Alberta and Northern Stroke Lead, Cardiovascular and Stroke Strategic Clinical Network, Alberta Health Services, Edmonton, commented on the study for this news organization. Like the authors, he said, “I don’t consider this study to definitively exclude the benefit of EC/IC bypass. More studies are required.”

Dr. Jeerakathil would like to see a study of a higher-risk group based on both clinical and hemodynamic blood flow criteria. In the current study, he said, “The trial group overall may not have been at high enough stroke risk to justify the up-front risks of the EC-IC bypass procedure.”

In addition, “The analysis method of Cox proportional hazards regression for the primary outcome did not fit the data when the perioperative period was combined with the period beyond 30 days,” he noted. “The researchers were open about this and did pivot and included a post hoc relative risk-based analysis, but the validity of their primary analysis is questionable.”

Furthermore, the study was “somewhat underpowered with a relatively small sample size and had the potential to miss clinically significant differences between groups,” he said. “It would be good to see a longer follow-up period of at least 5 years added to this trial and used in future trials, rather than 2 years.”

“Lastly,” he said, “it’s difficult to ignore the reduction in recurrent stroke events over the 30-day to 2-year time period associated with EC-IC bypass (from 10.3% down to 2%). This reduction alone shows the procedure has some potential to prevent stroke and would argue for more trials.”

EC-IC could be considered for patients who have failed other medical therapies and have more substantial evidence of compromised blood flow to the brain than those in the CMOSS trial, he noted, as many of these patients have few other options. “In our center and many other centers, the approach to EC-IC bypass is probably much more selective than used in the trial.”

Dr. Jeerakathil concluded, “Clinicians should be cautious about offering the procedure to patients with just mildly delayed blood flow in the hemisphere affected by the occluded artery and those who have not yet failed maximal medical therapy.”

But Seemant Chaturvedi, MD, and J. Marc Simard, MD, PhD, both of the University of Maryland, Baltimore, are not as optimistic about the potential for EC-IC.

Writing in a related editorial, they conclude that the results with EC-IC bypass surgery in randomized trials “remain unimpressive. Until a better understanding of the unique hemodynamic features of the brain is achieved, it will be difficult for neurosurgeons to continue offering this procedure to patients with ICA or MCA occlusion. Intensive, multifaceted medical therapy remains the first-line treatment for [these] patients.”

The study was supported by a research grant from the National Health Commission of the People’s Republic of China. Dr. Jiao, Dr. Jeerakathil, Dr. Chaturvedi, and Dr. Simard reported no conflicts of interest.

A version of this article first appeared on Medscape.com.

For most symptomatic patients with atherosclerotic occlusion of the internal carotid artery (ICA) or middle cerebral artery (MCA), adding extracranial-intracranial (EC-IC) bypass surgery to medical therapy did not reduce stroke or death in comparison with medical therapy alone in the latest randomized trial comparing the two interventions.

However, subgroup analyses suggest a potential benefit of surgery for certain patients, such as those with MCA vs. ICA occlusion, mean transit time greater than 6 seconds, or regional blood flow of 0.8 or less.

“We were disappointed by the results,” Liqun Jiao, MD, of the National Center for Neurological Disorders in Beijing, told this news organization. “We were expecting to demonstrate a benefit from EC-IC bypass surgery over medical treatment alone in symptomatic patients with ICA or MCA occlusion and hemodynamic insufficiency, per our original hypothesis.”

Although the study showed improved efficacy and safety for the surgical procedure, he said, “The progress of medical treatment is even better.”

The study was published online in JAMA.
 

Subgroup analyses promising

Previous randomized clinical trials, including the EC/IC Bypass Study and the Carotid Occlusion Surgery Study (COSS), showed no benefit in stroke prevention for patients with atherosclerotic occlusion of the ICA or MCA.

However, in light of improvements over the years in surgical techniques and patient selection, the authors conducted the Carotid and Middle Cerebral Artery Occlusion Surgery Study (CMOSS), a multicenter, randomized, open-label trial comparing EC-IC bypass surgery plus medical therapy, consisting of antiplatelet therapy and control of stroke risk factors, with medical therapy alone in symptomatic patients with ICA or MCA occlusion and hemodynamic insufficiency, with refined patient and operator selection.

A total of 324 patients (median age, 52.7 years; 79% men) in 13 centers in China were included; 309 patients (95%) completed the study.

The primary outcome was a composite of stroke or death within 30 days or ipsilateral ischemic stroke beyond 30 days through 2 years after randomization.

Secondary outcomes included, among others, any stroke or death within 2 years and fatal stroke within 2 years.

No significant difference was found for the primary outcome between the surgical group (8.6%) and the medical group (12.3%).

The 30-day risk of stroke or death was 6.2% in the surgery group, versus 1.8% (3/163) for the medical group. The risk of ipsilateral ischemic stroke beyond 30 days through 2 years was 2%, versus 10.3% – nonsignificant differences.

Furthermore, none of the prespecified secondary endpoints showed a significant difference, including any stroke or death within 2 years (9.9% vs. 15.3%; hazard ratio, 0.69) and fatal stroke within 2 years (2% vs. none).

Despite the findings, “We are encouraged by the subgroup analysis and the trend of long-term outcomes,” Dr. Jiao said. “We will continue to finish 5-10 years of follow-up to see whether the benefit of bypass surgery can be identified.”

The team has also launched the CMOSS-2 trial with a refined study design based on the results of subgroup analysis of the CMOSS study.

CMOSS-2 is recruiting patients with symptomatic chronic occlusion of the MCA and severe hemodynamic insufficiency in 13 sites in China. The primary outcome is ischemic stroke in the territory of the target artery within 24 months after randomization.
 

Can’t exclude benefit

Thomas Jeerakathil, MD, a professor at the University of Alberta and Northern Stroke Lead, Cardiovascular and Stroke Strategic Clinical Network, Alberta Health Services, Edmonton, commented on the study for this news organization. Like the authors, he said, “I don’t consider this study to definitively exclude the benefit of EC/IC bypass. More studies are required.”

Dr. Jeerakathil would like to see a study of a higher-risk group based on both clinical and hemodynamic blood flow criteria. In the current study, he said, “The trial group overall may not have been at high enough stroke risk to justify the up-front risks of the EC-IC bypass procedure.”

In addition, “The analysis method of Cox proportional hazards regression for the primary outcome did not fit the data when the perioperative period was combined with the period beyond 30 days,” he noted. “The researchers were open about this and did pivot and included a post hoc relative risk-based analysis, but the validity of their primary analysis is questionable.”

Furthermore, the study was “somewhat underpowered with a relatively small sample size and had the potential to miss clinically significant differences between groups,” he said. “It would be good to see a longer follow-up period of at least 5 years added to this trial and used in future trials, rather than 2 years.”

“Lastly,” he said, “it’s difficult to ignore the reduction in recurrent stroke events over the 30-day to 2-year time period associated with EC-IC bypass (from 10.3% down to 2%). This reduction alone shows the procedure has some potential to prevent stroke and would argue for more trials.”

EC-IC could be considered for patients who have failed other medical therapies and have more substantial evidence of compromised blood flow to the brain than those in the CMOSS trial, he noted, as many of these patients have few other options. “In our center and many other centers, the approach to EC-IC bypass is probably much more selective than used in the trial.”

Dr. Jeerakathil concluded, “Clinicians should be cautious about offering the procedure to patients with just mildly delayed blood flow in the hemisphere affected by the occluded artery and those who have not yet failed maximal medical therapy.”

But Seemant Chaturvedi, MD, and J. Marc Simard, MD, PhD, both of the University of Maryland, Baltimore, are not as optimistic about the potential for EC-IC.

Writing in a related editorial, they conclude that the results with EC-IC bypass surgery in randomized trials “remain unimpressive. Until a better understanding of the unique hemodynamic features of the brain is achieved, it will be difficult for neurosurgeons to continue offering this procedure to patients with ICA or MCA occlusion. Intensive, multifaceted medical therapy remains the first-line treatment for [these] patients.”

The study was supported by a research grant from the National Health Commission of the People’s Republic of China. Dr. Jiao, Dr. Jeerakathil, Dr. Chaturvedi, and Dr. Simard reported no conflicts of interest.

A version of this article first appeared on Medscape.com.

Traumatic brain injury (TBI) that occurs in early adulthood is associated with cognitive decline in later life, results from a study of identical twins who served in World War II show.

The research, which included almost 9,000 individuals, showed that twins who had experienced a TBI were more likely to have lower cognitive function at age 70 versus their twin who did not experience a TBI, especially if they had lost consciousness or were older than age 24 at the time of injury. In addition, their cognitive decline occurred at a more rapid rate.

“We know that TBI increases the risk of developing Alzheimer’s disease and other dementias in later life, but we haven’t known about TBI’s effect on cognitive decline that does not quite meet the threshold for dementia,” study investigator Marianne Chanti-Ketterl, PhD, Duke University, Durham, N.C., said in an interview.

“We know that TBI increases the risk of dementia in later life, but we haven’t known if TBI affects cognitive function, causes cognitive decline that has not progressed to the point of severity with Alzheimer’s or dementia,” she added.

Being able to study the impact of TBI in monozygotic twins gives this study a unique strength, she noted.

“The important thing about this is that they are monozygotic twins, and we know they shared a lot of early life exposure, and almost 100% genetics,” Dr. Chanti-Ketterl said.

The study was published online in Neurology.

For the study, the investigators assessed 8,662 participants born between 1917 and 1927 who were part of the National Academy of Sciences National Research Council’s Twin Registry. The registry is composed of male veterans of World War II with a history of TBI, as reported by themselves or a caregiver.

The men were followed up for many years as part of the registry, but cognitive assessment only began in the 1990s. They were followed up at four different time points, at which time the Telephone Interview for Cognitive Status (TICS-m), an alternative to the Mini-Mental State Examination that must be given in person, was administered.

A total of 25% of participants had experienced concussion in their lifetime. Of this cohort, there were 589 pairs of monozygotic twins who were discordant (one twin had TBI and the other had not).

Among the monozygotic twin cohort, a history of any TBI and being older than age 24 at the time of TBI were associated with lower TICS-m scores.

A twin who experienced TBI after age 24 scored 0.59 points lower on the TICS-m at age 70 than his twin with no TBI, and cognitive function declined faster, by 0.05 points per year.
 

First study of its kind

Holly Elser, MD, PhD, MPH, an epidemiologist and resident physician in neurology at the University of Pennsylvania, Philadelphia, and coauthor of an accompanying editorial, said in an interview that the study’s twin design was a definite strength.

“There are lots of papers that have remarked on the apparent association between head injury and subsequent dementia or cognitive decline, but to my knowledge, this is one of the first, if not the first, to use a twin study design, which has the unique advantage of having better control over early life and genetic factors than would ever typically be possible in a dataset of unrelated adults,” said Dr. Elser.

She added that the study findings “strengthen our understanding of the relationship between TBI and later cognitive decline, so I think there is an etiologic value to the study.”

However, Dr. Elser noted that the composition of the study population may limit the extent to which the results apply to contemporary populations.

“This was a population of White male twins born between 1917 and 1927,” she noted. “However, does the experience of people who were in the military generalize to civilian populations? Are twins representative of the general population or are they unique in terms of their risk factors?”

It is always important to emphasize inclusivity in clinical research, and in dementia research in particular, Dr. Elser added.

“There are many examples of instances where racialized and otherwise economically marginalized groups have been excluded from analysis, which is problematic because there are already economically and socially marginalized groups who disproportionately bear the brunt of dementia.

“This is not a criticism of the authors’ work, that their data didn’t include a more diverse patient base, but I think it is an important reminder that we should always interpret study findings within the limitations of the data. It’s a reminder to be thoughtful about taking explicit steps to include more diverse groups in future research,” she said.

The study was funded by the National Institute on Aging/National Institutes of Health and the Department of Defense. Dr. Chanti-Ketterl and Dr. Elser have reported no relevant financial relationships.

A version of this article appeared on Medscape.com.

Traumatic brain injury (TBI) that occurs in early adulthood is associated with cognitive decline in later life, results from a study of identical twins who served in World War II show.

The research, which included almost 9,000 individuals, showed that twins who had experienced a TBI were more likely to have lower cognitive function at age 70 versus their twin who did not experience a TBI, especially if they had lost consciousness or were older than age 24 at the time of injury. In addition, their cognitive decline occurred at a more rapid rate.

“We know that TBI increases the risk of developing Alzheimer’s disease and other dementias in later life, but we haven’t known about TBI’s effect on cognitive decline that does not quite meet the threshold for dementia,” study investigator Marianne Chanti-Ketterl, PhD, Duke University, Durham, N.C., said in an interview.

“We know that TBI increases the risk of dementia in later life, but we haven’t known if TBI affects cognitive function, causes cognitive decline that has not progressed to the point of severity with Alzheimer’s or dementia,” she added.

Being able to study the impact of TBI in monozygotic twins gives this study a unique strength, she noted.

“The important thing about this is that they are monozygotic twins, and we know they shared a lot of early life exposure, and almost 100% genetics,” Dr. Chanti-Ketterl said.

The study was published online in Neurology.

For the study, the investigators assessed 8,662 participants born between 1917 and 1927 who were part of the National Academy of Sciences National Research Council’s Twin Registry. The registry is composed of male veterans of World War II with a history of TBI, as reported by themselves or a caregiver.

The men were followed up for many years as part of the registry, but cognitive assessment only began in the 1990s. They were followed up at four different time points, at which time the Telephone Interview for Cognitive Status (TICS-m), an alternative to the Mini-Mental State Examination that must be given in person, was administered.

A total of 25% of participants had experienced concussion in their lifetime. Of this cohort, there were 589 pairs of monozygotic twins who were discordant (one twin had TBI and the other had not).

Among the monozygotic twin cohort, a history of any TBI and being older than age 24 at the time of TBI were associated with lower TICS-m scores.

A twin who experienced TBI after age 24 scored 0.59 points lower on the TICS-m at age 70 than his twin with no TBI, and cognitive function declined faster, by 0.05 points per year.
 

First study of its kind

Holly Elser, MD, PhD, MPH, an epidemiologist and resident physician in neurology at the University of Pennsylvania, Philadelphia, and coauthor of an accompanying editorial, said in an interview that the study’s twin design was a definite strength.

“There are lots of papers that have remarked on the apparent association between head injury and subsequent dementia or cognitive decline, but to my knowledge, this is one of the first, if not the first, to use a twin study design, which has the unique advantage of having better control over early life and genetic factors than would ever typically be possible in a dataset of unrelated adults,” said Dr. Elser.

She added that the study findings “strengthen our understanding of the relationship between TBI and later cognitive decline, so I think there is an etiologic value to the study.”

However, Dr. Elser noted that the composition of the study population may limit the extent to which the results apply to contemporary populations.

“This was a population of White male twins born between 1917 and 1927,” she noted. “However, does the experience of people who were in the military generalize to civilian populations? Are twins representative of the general population or are they unique in terms of their risk factors?”

It is always important to emphasize inclusivity in clinical research, and in dementia research in particular, Dr. Elser added.

“There are many examples of instances where racialized and otherwise economically marginalized groups have been excluded from analysis, which is problematic because there are already economically and socially marginalized groups who disproportionately bear the brunt of dementia.

“This is not a criticism of the authors’ work, that their data didn’t include a more diverse patient base, but I think it is an important reminder that we should always interpret study findings within the limitations of the data. It’s a reminder to be thoughtful about taking explicit steps to include more diverse groups in future research,” she said.

The study was funded by the National Institute on Aging/National Institutes of Health and the Department of Defense. Dr. Chanti-Ketterl and Dr. Elser have reported no relevant financial relationships.

A version of this article appeared on Medscape.com.

Traumatic brain injury (TBI) that occurs in early adulthood is associated with cognitive decline in later life, results from a study of identical twins who served in World War II show.

The research, which included almost 9,000 individuals, showed that twins who had experienced a TBI were more likely to have lower cognitive function at age 70 versus their twin who did not experience a TBI, especially if they had lost consciousness or were older than age 24 at the time of injury. In addition, their cognitive decline occurred at a more rapid rate.

“We know that TBI increases the risk of developing Alzheimer’s disease and other dementias in later life, but we haven’t known about TBI’s effect on cognitive decline that does not quite meet the threshold for dementia,” study investigator Marianne Chanti-Ketterl, PhD, Duke University, Durham, N.C., said in an interview.

“We know that TBI increases the risk of dementia in later life, but we haven’t known if TBI affects cognitive function, causes cognitive decline that has not progressed to the point of severity with Alzheimer’s or dementia,” she added.

Being able to study the impact of TBI in monozygotic twins gives this study a unique strength, she noted.

“The important thing about this is that they are monozygotic twins, and we know they shared a lot of early life exposure, and almost 100% genetics,” Dr. Chanti-Ketterl said.

The study was published online in Neurology.

For the study, the investigators assessed 8,662 participants born between 1917 and 1927 who were part of the National Academy of Sciences National Research Council’s Twin Registry. The registry is composed of male veterans of World War II with a history of TBI, as reported by themselves or a caregiver.

The men were followed up for many years as part of the registry, but cognitive assessment only began in the 1990s. They were followed up at four different time points, at which time the Telephone Interview for Cognitive Status (TICS-m), an alternative to the Mini-Mental State Examination that must be given in person, was administered.

A total of 25% of participants had experienced concussion in their lifetime. Of this cohort, there were 589 pairs of monozygotic twins who were discordant (one twin had TBI and the other had not).

Among the monozygotic twin cohort, a history of any TBI and being older than age 24 at the time of TBI were associated with lower TICS-m scores.

A twin who experienced TBI after age 24 scored 0.59 points lower on the TICS-m at age 70 than his twin with no TBI, and cognitive function declined faster, by 0.05 points per year.
 

First study of its kind

Holly Elser, MD, PhD, MPH, an epidemiologist and resident physician in neurology at the University of Pennsylvania, Philadelphia, and coauthor of an accompanying editorial, said in an interview that the study’s twin design was a definite strength.

“There are lots of papers that have remarked on the apparent association between head injury and subsequent dementia or cognitive decline, but to my knowledge, this is one of the first, if not the first, to use a twin study design, which has the unique advantage of having better control over early life and genetic factors than would ever typically be possible in a dataset of unrelated adults,” said Dr. Elser.

She added that the study findings “strengthen our understanding of the relationship between TBI and later cognitive decline, so I think there is an etiologic value to the study.”

However, Dr. Elser noted that the composition of the study population may limit the extent to which the results apply to contemporary populations.

“This was a population of White male twins born between 1917 and 1927,” she noted. “However, does the experience of people who were in the military generalize to civilian populations? Are twins representative of the general population or are they unique in terms of their risk factors?”

It is always important to emphasize inclusivity in clinical research, and in dementia research in particular, Dr. Elser added.

“There are many examples of instances where racialized and otherwise economically marginalized groups have been excluded from analysis, which is problematic because there are already economically and socially marginalized groups who disproportionately bear the brunt of dementia.

“This is not a criticism of the authors’ work, that their data didn’t include a more diverse patient base, but I think it is an important reminder that we should always interpret study findings within the limitations of the data. It’s a reminder to be thoughtful about taking explicit steps to include more diverse groups in future research,” she said.

The study was funded by the National Institute on Aging/National Institutes of Health and the Department of Defense. Dr. Chanti-Ketterl and Dr. Elser have reported no relevant financial relationships.

A version of this article appeared on Medscape.com.

TOPLINE:

Cerebral palsy (CP) affects 1-4 per 1,000 live births in the United States. A new cohort study found children conceived during the winter and spring months appear to have a slightly higher risk for developing CP than those conceived during the summer. Fall months carried about the same or only slightly higher risk of CP than summer months.

METHODOLOGY:

• Researchers examined data from nearly 4.5 million live births registered in California between 2007 and 2015, exploring if the season of conception could serve as an indicator of exposure to environmental risk factors.
• For instance, infants conceived in winter months may have higher exposure to viruses like influenza. In California, agricultural pesticides are most often applied in summer months, when pregnant people would be in their first or second trimester and receive their most exposure to the fine particulates, the authors hypothesize.
• Almost 4,700 babies in the study population were diagnosed with CP. Researchers also considered the role of preterm birth as a potential mediating factor, and adjusted for sociodemographic characteristics such as maternal age, race, education, smoking during pregnancy, and body mass index.

TAKEAWAY:

• The study found that children conceived in winter and spring had a 9% (95% confidence interval, 1.01-1.19) to 10% (95% CI, 1.02-1.20) higher risk of developing CP than those conceived in the summer.
• Children conceived in January, February, or May carried a 15% higher risk, compared with babies conceived in July.
• The risk was more pronounced among mothers with low education levels or living in neighborhoods where residents have high rates of unemployment, single-parent households, multiunit households, and lower rates of high school graduates.

IN PRACTICE:

The researchers noted that possible explanations for the seasonal link to CP risk may include the prevalence of maternal infections during pregnancy, variations in exposure to pesticides, and seasonal patterns for air pollution. “Investigating seasonal variations in disease occurrence can provide clues about etiologically relevant factors.”

SOURCE:

Lead author Haoran Zhou, MPH, Yale University, New Haven, Conn., and colleagues published their findings online in JAMA Network Open. The study was partly supported by a grant from the American Academy for Cerebral Palsy and Developmental Medicine.

LIMITATIONS:

The study may not have fully captured all children with CP in the cohort due to the possibility of misclassification. The findings may not be generalizable beyond California. The overall increased risk associated with the season of conception was relatively small, suggesting family planning strategies may not need to change based on these findings. The exact mechanisms involving potential environmental factors need further investigation.

DISCLOSURES:

The authors reported no relevant financial relationships.

A version of this article first appeared on Medscape.com.

TOPLINE:

Cerebral palsy (CP) affects 1-4 per 1,000 live births in the United States. A new cohort study found children conceived during the winter and spring months appear to have a slightly higher risk for developing CP than those conceived during the summer. Fall months carried about the same or only slightly higher risk of CP than summer months.

METHODOLOGY:

• Researchers examined data from nearly 4.5 million live births registered in California between 2007 and 2015, exploring if the season of conception could serve as an indicator of exposure to environmental risk factors.
• For instance, infants conceived in winter months may have higher exposure to viruses like influenza. In California, agricultural pesticides are most often applied in summer months, when pregnant people would be in their first or second trimester and receive their most exposure to the fine particulates, the authors hypothesize.
• Almost 4,700 babies in the study population were diagnosed with CP. Researchers also considered the role of preterm birth as a potential mediating factor, and adjusted for sociodemographic characteristics such as maternal age, race, education, smoking during pregnancy, and body mass index.

TAKEAWAY:

• The study found that children conceived in winter and spring had a 9% (95% confidence interval, 1.01-1.19) to 10% (95% CI, 1.02-1.20) higher risk of developing CP than those conceived in the summer.
• Children conceived in January, February, or May carried a 15% higher risk, compared with babies conceived in July.
• The risk was more pronounced among mothers with low education levels or living in neighborhoods where residents have high rates of unemployment, single-parent households, multiunit households, and lower rates of high school graduates.

IN PRACTICE:

The researchers noted that possible explanations for the seasonal link to CP risk may include the prevalence of maternal infections during pregnancy, variations in exposure to pesticides, and seasonal patterns for air pollution. “Investigating seasonal variations in disease occurrence can provide clues about etiologically relevant factors.”

SOURCE:

Lead author Haoran Zhou, MPH, Yale University, New Haven, Conn., and colleagues published their findings online in JAMA Network Open. The study was partly supported by a grant from the American Academy for Cerebral Palsy and Developmental Medicine.

LIMITATIONS:

The study may not have fully captured all children with CP in the cohort due to the possibility of misclassification. The findings may not be generalizable beyond California. The overall increased risk associated with the season of conception was relatively small, suggesting family planning strategies may not need to change based on these findings. The exact mechanisms involving potential environmental factors need further investigation.

DISCLOSURES:

The authors reported no relevant financial relationships.

A version of this article first appeared on Medscape.com.

TOPLINE:

Cerebral palsy (CP) affects 1-4 per 1,000 live births in the United States. A new cohort study found children conceived during the winter and spring months appear to have a slightly higher risk for developing CP than those conceived during the summer. Fall months carried about the same or only slightly higher risk of CP than summer months.

METHODOLOGY:

• Researchers examined data from nearly 4.5 million live births registered in California between 2007 and 2015, exploring if the season of conception could serve as an indicator of exposure to environmental risk factors.
• For instance, infants conceived in winter months may have higher exposure to viruses like influenza. In California, agricultural pesticides are most often applied in summer months, when pregnant people would be in their first or second trimester and receive their most exposure to the fine particulates, the authors hypothesize.
• Almost 4,700 babies in the study population were diagnosed with CP. Researchers also considered the role of preterm birth as a potential mediating factor, and adjusted for sociodemographic characteristics such as maternal age, race, education, smoking during pregnancy, and body mass index.

TAKEAWAY:

• The study found that children conceived in winter and spring had a 9% (95% confidence interval, 1.01-1.19) to 10% (95% CI, 1.02-1.20) higher risk of developing CP than those conceived in the summer.
• Children conceived in January, February, or May carried a 15% higher risk, compared with babies conceived in July.
• The risk was more pronounced among mothers with low education levels or living in neighborhoods where residents have high rates of unemployment, single-parent households, multiunit households, and lower rates of high school graduates.

IN PRACTICE:

The researchers noted that possible explanations for the seasonal link to CP risk may include the prevalence of maternal infections during pregnancy, variations in exposure to pesticides, and seasonal patterns for air pollution. “Investigating seasonal variations in disease occurrence can provide clues about etiologically relevant factors.”

SOURCE:

Lead author Haoran Zhou, MPH, Yale University, New Haven, Conn., and colleagues published their findings online in JAMA Network Open. The study was partly supported by a grant from the American Academy for Cerebral Palsy and Developmental Medicine.

LIMITATIONS:

The study may not have fully captured all children with CP in the cohort due to the possibility of misclassification. The findings may not be generalizable beyond California. The overall increased risk associated with the season of conception was relatively small, suggesting family planning strategies may not need to change based on these findings. The exact mechanisms involving potential environmental factors need further investigation.

DISCLOSURES:

The authors reported no relevant financial relationships.

A version of this article first appeared on Medscape.com.

A newly published scientific statement from the American Heart Association focuses on the impact of aggressive low-density lipoprotein cholesterol (LDL-C) lowering on the risk for dementia and hemorrhagic stroke.

“The brain is the body’s most cholesterol-rich organ, and some have questioned whether aggressive LDL-C lowering induces abnormal structural and functional changes,” the writing group, led by Larry Goldstein, MD, chair, department of neurology, University of Kentucky, Lexington, points out.

The 39-page AHA scientific statement, titled “Aggressive LDL-C Lowering and the Brain: Impact on Risk for Dementia and Hemorrhagic Stroke,” was published online in the journal Arteriosclerosis, Thrombosis, and Vascular Biology.

The objective was to evaluate contemporary evidence that either supports or refutes the conclusion that aggressive LDL-C lowering or lipid lowering exerts toxic effects on the brain, leading to cognitive impairment or dementia or hemorrhagic stroke.

The eight-member writing group used literature reviews, references to published clinical and epidemiology studies, clinical and public health guidelines, authoritative statements, and expert opinion to summarize the latest evidence and identify gaps in current knowledge.

They reached four main conclusions:

• First, the available data “consistently” show that LDL-C lowering reduces the risk of atherosclerotic cardiovascular disease-related events in high-risk groups.
• Second, although some older retrospective, case-control, and prospective longitudinal studies suggest that statins and LDL-C lowering are associated with cognitive impairment or dementia, the “preponderance” of observational studies and data from randomized trials do not support this conclusion, at least among trials with median follow-up of up to 6 years. The group says additional studies are needed to ensure cognitive safety over longer periods of time. For now, contemporary guidelines recommending the risk-stratified attainment of lipid-lowering goals are “reasonable,” they conclude.
• Third, the risk for hemorrhagic stroke associated with statin therapy in patients without a history of cerebrovascular disease is “small and consistently nonsignificant.” They found no evidence that PCSK9 inhibitors or ezetimibe (Zetia) increases bleeding risk. Further, there is “no indication” that patients or populations with lifelong low LDL-C have enhanced vulnerability to hemorrhagic stroke, and there is “little evidence” that achieving very low levels of LDL-C increases that risk. What is clear, the writing group says, is that lower LDL-C levels correlate with lower risk of overall stroke and stroke recurrence, mostly related to a reduction in ischemic stroke. “Concern about hemorrhagic stroke risk should not deter a clinician from treating LDL-C to guideline-recommended risk-stratified targets,” the writing group says.
• Fourth, the group notes that data reflecting the risk of hemorrhagic stroke with statin therapy among patients with a history of hemorrhagic stroke are not robust. PCSK9 inhibitors have not been adequately tested in patients with prior intracerebral hemorrhage. Lipid lowering in these populations requires more focused study.

The research had no commercial funding. A list of disclosures for the writing group is available with the original article.

A version of this article appeared on Medscape.com.

A newly published scientific statement from the American Heart Association focuses on the impact of aggressive low-density lipoprotein cholesterol (LDL-C) lowering on the risk for dementia and hemorrhagic stroke.

“The brain is the body’s most cholesterol-rich organ, and some have questioned whether aggressive LDL-C lowering induces abnormal structural and functional changes,” the writing group, led by Larry Goldstein, MD, chair, department of neurology, University of Kentucky, Lexington, points out.

The 39-page AHA scientific statement, titled “Aggressive LDL-C Lowering and the Brain: Impact on Risk for Dementia and Hemorrhagic Stroke,” was published online in the journal Arteriosclerosis, Thrombosis, and Vascular Biology.

The objective was to evaluate contemporary evidence that either supports or refutes the conclusion that aggressive LDL-C lowering or lipid lowering exerts toxic effects on the brain, leading to cognitive impairment or dementia or hemorrhagic stroke.

The eight-member writing group used literature reviews, references to published clinical and epidemiology studies, clinical and public health guidelines, authoritative statements, and expert opinion to summarize the latest evidence and identify gaps in current knowledge.

They reached four main conclusions:

• First, the available data “consistently” show that LDL-C lowering reduces the risk of atherosclerotic cardiovascular disease-related events in high-risk groups.
• Second, although some older retrospective, case-control, and prospective longitudinal studies suggest that statins and LDL-C lowering are associated with cognitive impairment or dementia, the “preponderance” of observational studies and data from randomized trials do not support this conclusion, at least among trials with median follow-up of up to 6 years. The group says additional studies are needed to ensure cognitive safety over longer periods of time. For now, contemporary guidelines recommending the risk-stratified attainment of lipid-lowering goals are “reasonable,” they conclude.
• Third, the risk for hemorrhagic stroke associated with statin therapy in patients without a history of cerebrovascular disease is “small and consistently nonsignificant.” They found no evidence that PCSK9 inhibitors or ezetimibe (Zetia) increases bleeding risk. Further, there is “no indication” that patients or populations with lifelong low LDL-C have enhanced vulnerability to hemorrhagic stroke, and there is “little evidence” that achieving very low levels of LDL-C increases that risk. What is clear, the writing group says, is that lower LDL-C levels correlate with lower risk of overall stroke and stroke recurrence, mostly related to a reduction in ischemic stroke. “Concern about hemorrhagic stroke risk should not deter a clinician from treating LDL-C to guideline-recommended risk-stratified targets,” the writing group says.
• Fourth, the group notes that data reflecting the risk of hemorrhagic stroke with statin therapy among patients with a history of hemorrhagic stroke are not robust. PCSK9 inhibitors have not been adequately tested in patients with prior intracerebral hemorrhage. Lipid lowering in these populations requires more focused study.

The research had no commercial funding. A list of disclosures for the writing group is available with the original article.

A version of this article appeared on Medscape.com.

A newly published scientific statement from the American Heart Association focuses on the impact of aggressive low-density lipoprotein cholesterol (LDL-C) lowering on the risk for dementia and hemorrhagic stroke.

“The brain is the body’s most cholesterol-rich organ, and some have questioned whether aggressive LDL-C lowering induces abnormal structural and functional changes,” the writing group, led by Larry Goldstein, MD, chair, department of neurology, University of Kentucky, Lexington, points out.

The 39-page AHA scientific statement, titled “Aggressive LDL-C Lowering and the Brain: Impact on Risk for Dementia and Hemorrhagic Stroke,” was published online in the journal Arteriosclerosis, Thrombosis, and Vascular Biology.

The objective was to evaluate contemporary evidence that either supports or refutes the conclusion that aggressive LDL-C lowering or lipid lowering exerts toxic effects on the brain, leading to cognitive impairment or dementia or hemorrhagic stroke.

The eight-member writing group used literature reviews, references to published clinical and epidemiology studies, clinical and public health guidelines, authoritative statements, and expert opinion to summarize the latest evidence and identify gaps in current knowledge.

They reached four main conclusions:

• First, the available data “consistently” show that LDL-C lowering reduces the risk of atherosclerotic cardiovascular disease-related events in high-risk groups.
• Second, although some older retrospective, case-control, and prospective longitudinal studies suggest that statins and LDL-C lowering are associated with cognitive impairment or dementia, the “preponderance” of observational studies and data from randomized trials do not support this conclusion, at least among trials with median follow-up of up to 6 years. The group says additional studies are needed to ensure cognitive safety over longer periods of time. For now, contemporary guidelines recommending the risk-stratified attainment of lipid-lowering goals are “reasonable,” they conclude.
• Third, the risk for hemorrhagic stroke associated with statin therapy in patients without a history of cerebrovascular disease is “small and consistently nonsignificant.” They found no evidence that PCSK9 inhibitors or ezetimibe (Zetia) increases bleeding risk. Further, there is “no indication” that patients or populations with lifelong low LDL-C have enhanced vulnerability to hemorrhagic stroke, and there is “little evidence” that achieving very low levels of LDL-C increases that risk. What is clear, the writing group says, is that lower LDL-C levels correlate with lower risk of overall stroke and stroke recurrence, mostly related to a reduction in ischemic stroke. “Concern about hemorrhagic stroke risk should not deter a clinician from treating LDL-C to guideline-recommended risk-stratified targets,” the writing group says.
• Fourth, the group notes that data reflecting the risk of hemorrhagic stroke with statin therapy among patients with a history of hemorrhagic stroke are not robust. PCSK9 inhibitors have not been adequately tested in patients with prior intracerebral hemorrhage. Lipid lowering in these populations requires more focused study.

The research had no commercial funding. A list of disclosures for the writing group is available with the original article.

A version of this article appeared on Medscape.com.

Lecanemab (Lequembi, Esai), an amyloid-beta–directed antibody therapy, is approved by the Food and Drug Administration for the treatment of Alzheimer’s disease (AD). But exactly how the drug clears amyloid-beta wasn’t clear.

Now new research suggests the drug, which was approved by the FDA in January, targets a particular molecular cascade, the plasma contact system, which drives amyloid-beta toxicity.

The investigators tested the effectiveness of various forms of amyloid-beta in activating the plasma contact system and found that amyloid-beta protofibrils, known to be the most toxic form of amyloid-beta, promoted the activation of this molecular cascade and that lecanemab inhibited pathway activation.

“In our study, we looked at lecanemab and found it can block the activation of the contact system, which could be one of the reasons that it works so well for AD,” study coinvestigator Erin Norris, PhD, research associate professor, Rockefeller University, New York, said in an interview.

The study was published online in the Proceedings of the National Academy of Science.
 

Unknown mechanism

“Many years ago, we started looking at the involvement of vascular dysfunction in AD,” Dr. Norris said. “We wanted to see whether or not irregular blood clotting or problems with blood flow was problematic in Alzheimer’s patients.”

The researchers found that fibrin, a major component involved in blood clotting, can extravasate into the brain.

“The blood-brain barrier can break down in Alzheimer’s, so things from the blood can move into the brain and deposit there,” she added. Fibrin then interacts with amyloid-beta, the major pathogenic protein in AD.

Dr. Norris explained that fibrin clots can form in two different ways. One is through the normal process that occurs when there’s an injury and bleeding. The second is through intrinsic clotting, which takes place through the contact system.

“We started looking into this system and found that the plasma of Alzheimer’s patients showed irregular levels of these enzymes and proteins that are part of the intrinsic clotting system compared to those of normal controls,” said Dr. Norris.

“This paper was an extension of years studying this pathway and these mechanisms. It was also inspired by the approval of lecanemab and its release for use in Alzheimer’s patients,” she added.

In previous research, the same researchers found that amyloid-beta has different forms. “It’s normally soluble, and it’s a very tiny molecule,” Dr. Norris said. “But over time, and in different situations, it can start to aggregate, becoming bigger and bigger.”
 

Implications beyond Alzheimer’s

Postmortem tissue analysis has found fibrillar plaques that are “clumped together.” These are insoluble and hard to get rid of, she said. “Protofibrils are the step before amyloid-beta forms fibrils and are considered to be the most toxic form, although the mechanism behind why it’s so toxic is not understood.”

Previous research has already shown that amyloid-beta can activate the contact system. The contact system has two “arms,” the first of which is involved with clotting, and the second with inflammation, Dr. Norris said. In fact, it’s the plasma contact system that links vascular and inflammatory pathways.

The plasma contact system leads to the clotting of fibrin, Dr. Norris continued. It activates factor XII, which leads to blood clotting by binding to coagulation factor XI.

The contact system also causes inflammation – the second “arm.” Bradykinin, a potent inflammatory molecule, is released by binding to high-molecular-weight kininogen (HK). In addition to inflammation, bradykinin can cause edema and blood-brain barrier permeability.

Although it’s been known that amyloid-beta can activate the contact system, the particular form of amyloid-beta implicated in this cascade has not been identified. And so, the researchers incubated amyloid-beta42 with human plasma, testing various types of amyloid-beta – monomers, oligomers, protofibrils, and fibrils – to see which would activate the contact system.

Amyloid-beta protofibrils promoted the activation of the contact system, as evidenced by several reactions, including activation of factor XII, while other forms of amyloid-beta did not. HK also “bound tightly” to amyloid-beta protofibrils, with “weaker” binding to other amyloid-beta species, the authors reported, confirming that amyloid-beta protofibrils bind to HK and factor XII.

Bradykinin levels were increased by amyloid-beta protofibrils, which also induced faster clotting, compared with other forms of amyloid-beta.

The researchers introduced lecanemab into the picture and found it “dramatically inhibited” contact system activation induced by amyloid-beta protofibrils. For example, it blocked the binding of factor XII to amyloid-beta. By contrast, human IgG (which the researchers used as a control) had no effect.

Additionally, lecanemab also prevented accelerated intrinsic coagulation in normal human plasma mediated by amyloid-beta protofibril.

Senior author Sidney Strickland, PhD, the Zachary and Elizabeth M. Fisher professor in Alzheimer’s and neurodegenerative disease, Rockefeller University, said in an interview: “One of the strong motivators for conducting this study was the fact that this drug, which is effective in AD, targets this specific form of amyloid-beta; but no one knows why it›s more toxic. We thought we could see if we could tie it to what we›re working on, and we found it ties in beautifully.”

The findings have implications that go beyond AD, Dr. Strickland said. “The contact system is implicated in lots of different pathologies, including sickle cell anemia, sepsis, inflammatory bowel disease, and so on.” Blocking the contact system might be a helpful approach in these conditions too.
 

Innovative, plausible, but still preliminary

In a comment, Heather M. Snyder, PhD, vice president of medical and scientific relations at the Alzheimer’s Association, called the investigation “innovative,” with ideas that are “certainly plausible.” However, “at this time, the work is preliminary and not conclusive.”

The hypothesized mechanisms for why amyloid (lecanemab’s target) is toxic to the brain “does incorporate important AD-related brain changes that have been observed in other studies, including inflammatory/immune changes and vascular-related changes,” said Dr. Snyder, who was not involved with the current study.

However, “additional studies that look both in model systems and in humans are needed to further illuminate these relationships,” Dr. Snyder said.

The study was supported by grants from the National Institutes of Health as well as the Robertson Therapeutic Development Fund, Samuel Newhouse Foundation, John A. Herrmann, and the May and Samuel Rudin Family Foundation. Dr. Norris, Dr. Strickland, and Dr. Snyder declared no relevant financial relationships.

A version of this article first appeared on Medscape.com.

Lecanemab (Lequembi, Esai), an amyloid-beta–directed antibody therapy, is approved by the Food and Drug Administration for the treatment of Alzheimer’s disease (AD). But exactly how the drug clears amyloid-beta wasn’t clear.

Now new research suggests the drug, which was approved by the FDA in January, targets a particular molecular cascade, the plasma contact system, which drives amyloid-beta toxicity.

The investigators tested the effectiveness of various forms of amyloid-beta in activating the plasma contact system and found that amyloid-beta protofibrils, known to be the most toxic form of amyloid-beta, promoted the activation of this molecular cascade and that lecanemab inhibited pathway activation.

“In our study, we looked at lecanemab and found it can block the activation of the contact system, which could be one of the reasons that it works so well for AD,” study coinvestigator Erin Norris, PhD, research associate professor, Rockefeller University, New York, said in an interview.

The study was published online in the Proceedings of the National Academy of Science.
 

Unknown mechanism

“Many years ago, we started looking at the involvement of vascular dysfunction in AD,” Dr. Norris said. “We wanted to see whether or not irregular blood clotting or problems with blood flow was problematic in Alzheimer’s patients.”

The researchers found that fibrin, a major component involved in blood clotting, can extravasate into the brain.

“The blood-brain barrier can break down in Alzheimer’s, so things from the blood can move into the brain and deposit there,” she added. Fibrin then interacts with amyloid-beta, the major pathogenic protein in AD.

Dr. Norris explained that fibrin clots can form in two different ways. One is through the normal process that occurs when there’s an injury and bleeding. The second is through intrinsic clotting, which takes place through the contact system.

“We started looking into this system and found that the plasma of Alzheimer’s patients showed irregular levels of these enzymes and proteins that are part of the intrinsic clotting system compared to those of normal controls,” said Dr. Norris.

“This paper was an extension of years studying this pathway and these mechanisms. It was also inspired by the approval of lecanemab and its release for use in Alzheimer’s patients,” she added.

In previous research, the same researchers found that amyloid-beta has different forms. “It’s normally soluble, and it’s a very tiny molecule,” Dr. Norris said. “But over time, and in different situations, it can start to aggregate, becoming bigger and bigger.”
 

Implications beyond Alzheimer’s

Postmortem tissue analysis has found fibrillar plaques that are “clumped together.” These are insoluble and hard to get rid of, she said. “Protofibrils are the step before amyloid-beta forms fibrils and are considered to be the most toxic form, although the mechanism behind why it’s so toxic is not understood.”

Previous research has already shown that amyloid-beta can activate the contact system. The contact system has two “arms,” the first of which is involved with clotting, and the second with inflammation, Dr. Norris said. In fact, it’s the plasma contact system that links vascular and inflammatory pathways.

The plasma contact system leads to the clotting of fibrin, Dr. Norris continued. It activates factor XII, which leads to blood clotting by binding to coagulation factor XI.

The contact system also causes inflammation – the second “arm.” Bradykinin, a potent inflammatory molecule, is released by binding to high-molecular-weight kininogen (HK). In addition to inflammation, bradykinin can cause edema and blood-brain barrier permeability.

Although it’s been known that amyloid-beta can activate the contact system, the particular form of amyloid-beta implicated in this cascade has not been identified. And so, the researchers incubated amyloid-beta42 with human plasma, testing various types of amyloid-beta – monomers, oligomers, protofibrils, and fibrils – to see which would activate the contact system.

Amyloid-beta protofibrils promoted the activation of the contact system, as evidenced by several reactions, including activation of factor XII, while other forms of amyloid-beta did not. HK also “bound tightly” to amyloid-beta protofibrils, with “weaker” binding to other amyloid-beta species, the authors reported, confirming that amyloid-beta protofibrils bind to HK and factor XII.

Bradykinin levels were increased by amyloid-beta protofibrils, which also induced faster clotting, compared with other forms of amyloid-beta.

The researchers introduced lecanemab into the picture and found it “dramatically inhibited” contact system activation induced by amyloid-beta protofibrils. For example, it blocked the binding of factor XII to amyloid-beta. By contrast, human IgG (which the researchers used as a control) had no effect.

Additionally, lecanemab also prevented accelerated intrinsic coagulation in normal human plasma mediated by amyloid-beta protofibril.

Senior author Sidney Strickland, PhD, the Zachary and Elizabeth M. Fisher professor in Alzheimer’s and neurodegenerative disease, Rockefeller University, said in an interview: “One of the strong motivators for conducting this study was the fact that this drug, which is effective in AD, targets this specific form of amyloid-beta; but no one knows why it›s more toxic. We thought we could see if we could tie it to what we›re working on, and we found it ties in beautifully.”

The findings have implications that go beyond AD, Dr. Strickland said. “The contact system is implicated in lots of different pathologies, including sickle cell anemia, sepsis, inflammatory bowel disease, and so on.” Blocking the contact system might be a helpful approach in these conditions too.
 

Innovative, plausible, but still preliminary

In a comment, Heather M. Snyder, PhD, vice president of medical and scientific relations at the Alzheimer’s Association, called the investigation “innovative,” with ideas that are “certainly plausible.” However, “at this time, the work is preliminary and not conclusive.”

The hypothesized mechanisms for why amyloid (lecanemab’s target) is toxic to the brain “does incorporate important AD-related brain changes that have been observed in other studies, including inflammatory/immune changes and vascular-related changes,” said Dr. Snyder, who was not involved with the current study.

However, “additional studies that look both in model systems and in humans are needed to further illuminate these relationships,” Dr. Snyder said.

The study was supported by grants from the National Institutes of Health as well as the Robertson Therapeutic Development Fund, Samuel Newhouse Foundation, John A. Herrmann, and the May and Samuel Rudin Family Foundation. Dr. Norris, Dr. Strickland, and Dr. Snyder declared no relevant financial relationships.

A version of this article first appeared on Medscape.com.

Lecanemab (Lequembi, Esai), an amyloid-beta–directed antibody therapy, is approved by the Food and Drug Administration for the treatment of Alzheimer’s disease (AD). But exactly how the drug clears amyloid-beta wasn’t clear.

Now new research suggests the drug, which was approved by the FDA in January, targets a particular molecular cascade, the plasma contact system, which drives amyloid-beta toxicity.

The investigators tested the effectiveness of various forms of amyloid-beta in activating the plasma contact system and found that amyloid-beta protofibrils, known to be the most toxic form of amyloid-beta, promoted the activation of this molecular cascade and that lecanemab inhibited pathway activation.

“In our study, we looked at lecanemab and found it can block the activation of the contact system, which could be one of the reasons that it works so well for AD,” study coinvestigator Erin Norris, PhD, research associate professor, Rockefeller University, New York, said in an interview.

The study was published online in the Proceedings of the National Academy of Science.
 

Unknown mechanism

“Many years ago, we started looking at the involvement of vascular dysfunction in AD,” Dr. Norris said. “We wanted to see whether or not irregular blood clotting or problems with blood flow was problematic in Alzheimer’s patients.”

The researchers found that fibrin, a major component involved in blood clotting, can extravasate into the brain.

“The blood-brain barrier can break down in Alzheimer’s, so things from the blood can move into the brain and deposit there,” she added. Fibrin then interacts with amyloid-beta, the major pathogenic protein in AD.

Dr. Norris explained that fibrin clots can form in two different ways. One is through the normal process that occurs when there’s an injury and bleeding. The second is through intrinsic clotting, which takes place through the contact system.

“We started looking into this system and found that the plasma of Alzheimer’s patients showed irregular levels of these enzymes and proteins that are part of the intrinsic clotting system compared to those of normal controls,” said Dr. Norris.

“This paper was an extension of years studying this pathway and these mechanisms. It was also inspired by the approval of lecanemab and its release for use in Alzheimer’s patients,” she added.

In previous research, the same researchers found that amyloid-beta has different forms. “It’s normally soluble, and it’s a very tiny molecule,” Dr. Norris said. “But over time, and in different situations, it can start to aggregate, becoming bigger and bigger.”
 

Implications beyond Alzheimer’s

Postmortem tissue analysis has found fibrillar plaques that are “clumped together.” These are insoluble and hard to get rid of, she said. “Protofibrils are the step before amyloid-beta forms fibrils and are considered to be the most toxic form, although the mechanism behind why it’s so toxic is not understood.”

Previous research has already shown that amyloid-beta can activate the contact system. The contact system has two “arms,” the first of which is involved with clotting, and the second with inflammation, Dr. Norris said. In fact, it’s the plasma contact system that links vascular and inflammatory pathways.

The plasma contact system leads to the clotting of fibrin, Dr. Norris continued. It activates factor XII, which leads to blood clotting by binding to coagulation factor XI.

The contact system also causes inflammation – the second “arm.” Bradykinin, a potent inflammatory molecule, is released by binding to high-molecular-weight kininogen (HK). In addition to inflammation, bradykinin can cause edema and blood-brain barrier permeability.

Although it’s been known that amyloid-beta can activate the contact system, the particular form of amyloid-beta implicated in this cascade has not been identified. And so, the researchers incubated amyloid-beta42 with human plasma, testing various types of amyloid-beta – monomers, oligomers, protofibrils, and fibrils – to see which would activate the contact system.

Amyloid-beta protofibrils promoted the activation of the contact system, as evidenced by several reactions, including activation of factor XII, while other forms of amyloid-beta did not. HK also “bound tightly” to amyloid-beta protofibrils, with “weaker” binding to other amyloid-beta species, the authors reported, confirming that amyloid-beta protofibrils bind to HK and factor XII.

Bradykinin levels were increased by amyloid-beta protofibrils, which also induced faster clotting, compared with other forms of amyloid-beta.

The researchers introduced lecanemab into the picture and found it “dramatically inhibited” contact system activation induced by amyloid-beta protofibrils. For example, it blocked the binding of factor XII to amyloid-beta. By contrast, human IgG (which the researchers used as a control) had no effect.

Additionally, lecanemab also prevented accelerated intrinsic coagulation in normal human plasma mediated by amyloid-beta protofibril.

Senior author Sidney Strickland, PhD, the Zachary and Elizabeth M. Fisher professor in Alzheimer’s and neurodegenerative disease, Rockefeller University, said in an interview: “One of the strong motivators for conducting this study was the fact that this drug, which is effective in AD, targets this specific form of amyloid-beta; but no one knows why it›s more toxic. We thought we could see if we could tie it to what we›re working on, and we found it ties in beautifully.”

The findings have implications that go beyond AD, Dr. Strickland said. “The contact system is implicated in lots of different pathologies, including sickle cell anemia, sepsis, inflammatory bowel disease, and so on.” Blocking the contact system might be a helpful approach in these conditions too.
 

Innovative, plausible, but still preliminary

In a comment, Heather M. Snyder, PhD, vice president of medical and scientific relations at the Alzheimer’s Association, called the investigation “innovative,” with ideas that are “certainly plausible.” However, “at this time, the work is preliminary and not conclusive.”

The hypothesized mechanisms for why amyloid (lecanemab’s target) is toxic to the brain “does incorporate important AD-related brain changes that have been observed in other studies, including inflammatory/immune changes and vascular-related changes,” said Dr. Snyder, who was not involved with the current study.

However, “additional studies that look both in model systems and in humans are needed to further illuminate these relationships,” Dr. Snyder said.

The study was supported by grants from the National Institutes of Health as well as the Robertson Therapeutic Development Fund, Samuel Newhouse Foundation, John A. Herrmann, and the May and Samuel Rudin Family Foundation. Dr. Norris, Dr. Strickland, and Dr. Snyder declared no relevant financial relationships.

A version of this article first appeared on Medscape.com.

New research hints at the possibility that cerebral amyloid angiopathy (CAA), a cause of spontaneous brain hemorrhage, can be transmitted via blood transfusion, raising the risk for spontaneous intracerebral hemorrhage (ICH) in transfusion recipients.

In an exploratory analysis, patients receiving red blood cell transfusions from donors who later developed multiple spontaneous ICHs, and were assumed to have CAA, were at a significantly increased risk of developing spontaneous ICH themselves.

“This may suggest a transfusion-transmissible agent associated with some types of spontaneous ICH, although the findings may be susceptible to selection bias and residual confounding, and further research is needed to investigate if transfusion transmission of CAA might explain this association,” the investigators noted.

“We do not think that the findings motivate a change in practice, and we should not let these results discourage otherwise indicated blood transfusion,” said lead author Jingcheng Zhao, MD, PhD, with Karolinska University Hospital Solna, Stockholm.

The study was published online  in the Journal of the American Medical Association.
 

Novel finding

Recent evidence suggests that CAA exhibits “prion-like” transmissivity, with reports of transmission through cadaveric pituitary hormone contaminated with amyloid-beta and tau protein, dura mater grafts, and possibly neurosurgical instruments.

CAA, which is characterized by the deposition of amyloid protein in the brain, is the second most common cause of spontaneous ICH. 

The researchers hypothesized that transfusion transmission of CAA may manifest through an increased risk for spontaneous ICH among transfusion recipients given blood from a donor with spontaneous ICH. To explore this hypothesis, they analyzed national registry data from Sweden and Denmark for ICH in recipients of red blood cell transfusion from donors who themselves had ICH over the years after their blood donations, with the assumption that donors with two or more ICHs would likely have CAA.

The cohort included nearly 760,000 individuals in Sweden (median age, 65 years; 59% women) and 330,000 in Denmark (median age, 64 years; 58% women), with a median follow-up of 5.8 and 6.1 years, respectively.

Receiving red blood cell transfusions from donors who later developed multiple spontaneous ICHs was associated with a greater than twofold increased risk of developing spontaneous ICH, compared with receiving a transfusion from donors without subsequent ICH (hazard ratio, 2.73; P < .001 in the Swedish cohort and HR, 2.32; P = .04 in the Danish cohort).

“The observed increased risk of spontaneous ICH associated with receiving a red blood cell transfusion from a donor who later developed multiple spontaneous ICHs, corresponding to a 30-year cumulative incidence difference of 2.3%, is a novel finding,” the researchers wrote.

There was no increase in post-transfusion ICH risk among recipients whose donors had a single post–blood-donation ICH.

The findings were robust to several of the sensitivity analyses.

A “negative” control analysis of post-transfusion ischemic stroke (instead of ICH) found no increased risk among recipients of blood from donors who had single or multiple ICHs.

This study provides “exploratory evidence of possible transfusion-transmission of a factor that causes ICHs, but more research is needed to confirm and to understand the mechanism,” said Dr. Zhao.

The researchers noted that they did not directly assess CAA but expect it would be more common among donors who develop multiple spontaneous ICHs, “as CAA-related ICH has been reported to have a 7-fold increase for recurrent ICHs, compared with non–CAA-related ICH.”
 

Worrisome finding or false alarm?

In an accompanying editorial, Steven Greenberg, MD, PhD, with the department of neurology, Harvard Medical School, Boston, said there are “good reasons to treat the possibility of CAA transmission via blood transfusion seriously – and good reasons to remain skeptical, at least for the present.”

“Powerful” arguments in support of the findings include the robust study methodology and the “striking” similarity in results from the two registries, which argues against a chance finding. Another is the negative control with ischemic stroke as the outcome, which argues against unsuspected confounding-causing associations with all types of stroke, Dr. Greenberg noted.

Arguments for remaining “unconvinced” of the association center on the weakness of evidence for a plausible biological mechanism for the finding, he points out. Another is the short-time course of ICHs after blood transfusion, which is “quite challenging to explain,” Dr. Greenberg said. Nearly half of the ICHs among blood recipients occurred within 5 years of transfusion, which is “dramatically” faster than the 30- to 40-year interval reported between neurosurgical exposure to cadaveric tissue and first ICH, he added.

Another related “mechanistic reservation” is the plausibility that a transmissible species of amyloid-beta could travel from blood to brain in sufficient quantities to trigger advanced CAA or Alzheimer disease pathology, he wrote.

He added the current study leaves him “squarely at the corner of anxiety and skepticism.”

With more than 10 million units of blood transfused in the United States each year, even a modest increase in risk for future brain hemorrhages or dementia conferred by “an uncommon – but as of now undetectable – donor trait would represent a substantial public health concern,” Dr. Greenberg wrote.

“From the standpoint of scientific plausibility, however, even this well-conducted analysis is at risk of representing a false alarm,” he cautioned.

Looking ahead, Dr. Greenberg said one clear direction is independent replication, ideally with datasets in which donor and recipient dementia can be reliably ascertained to assess the possibility of Alzheimer’s disease as well as CAA transmissibility.

“The other challenge is for experimental biologists to consider the alternative possibility of transfusion-related acceleration of downstream steps in the CAA-ICH pathway, such as the vessel remodeling by which amyloid beta–laden vessels proceed to rupture and bleed.”

“The current study is not yet a reason for alarm, certainly not a reason to avoid otherwise indicated blood transfusion, but it is a strong call for more scientific digging,” Dr. Greenberg concluded.

The study was funded by grants from the Karolinska Institute, the Swedish Research Council, and Region Stockholm. Dr. Zhao and Dr. Greenberg report no relevant financial relationships.

A version of this article first appeared on Medscape.com.

New research hints at the possibility that cerebral amyloid angiopathy (CAA), a cause of spontaneous brain hemorrhage, can be transmitted via blood transfusion, raising the risk for spontaneous intracerebral hemorrhage (ICH) in transfusion recipients.

In an exploratory analysis, patients receiving red blood cell transfusions from donors who later developed multiple spontaneous ICHs, and were assumed to have CAA, were at a significantly increased risk of developing spontaneous ICH themselves.

“This may suggest a transfusion-transmissible agent associated with some types of spontaneous ICH, although the findings may be susceptible to selection bias and residual confounding, and further research is needed to investigate if transfusion transmission of CAA might explain this association,” the investigators noted.

“We do not think that the findings motivate a change in practice, and we should not let these results discourage otherwise indicated blood transfusion,” said lead author Jingcheng Zhao, MD, PhD, with Karolinska University Hospital Solna, Stockholm.

The study was published online  in the Journal of the American Medical Association.
 

Novel finding

Recent evidence suggests that CAA exhibits “prion-like” transmissivity, with reports of transmission through cadaveric pituitary hormone contaminated with amyloid-beta and tau protein, dura mater grafts, and possibly neurosurgical instruments.

CAA, which is characterized by the deposition of amyloid protein in the brain, is the second most common cause of spontaneous ICH. 

The researchers hypothesized that transfusion transmission of CAA may manifest through an increased risk for spontaneous ICH among transfusion recipients given blood from a donor with spontaneous ICH. To explore this hypothesis, they analyzed national registry data from Sweden and Denmark for ICH in recipients of red blood cell transfusion from donors who themselves had ICH over the years after their blood donations, with the assumption that donors with two or more ICHs would likely have CAA.

The cohort included nearly 760,000 individuals in Sweden (median age, 65 years; 59% women) and 330,000 in Denmark (median age, 64 years; 58% women), with a median follow-up of 5.8 and 6.1 years, respectively.

Receiving red blood cell transfusions from donors who later developed multiple spontaneous ICHs was associated with a greater than twofold increased risk of developing spontaneous ICH, compared with receiving a transfusion from donors without subsequent ICH (hazard ratio, 2.73; P < .001 in the Swedish cohort and HR, 2.32; P = .04 in the Danish cohort).

“The observed increased risk of spontaneous ICH associated with receiving a red blood cell transfusion from a donor who later developed multiple spontaneous ICHs, corresponding to a 30-year cumulative incidence difference of 2.3%, is a novel finding,” the researchers wrote.

There was no increase in post-transfusion ICH risk among recipients whose donors had a single post–blood-donation ICH.

The findings were robust to several of the sensitivity analyses.

A “negative” control analysis of post-transfusion ischemic stroke (instead of ICH) found no increased risk among recipients of blood from donors who had single or multiple ICHs.

This study provides “exploratory evidence of possible transfusion-transmission of a factor that causes ICHs, but more research is needed to confirm and to understand the mechanism,” said Dr. Zhao.

The researchers noted that they did not directly assess CAA but expect it would be more common among donors who develop multiple spontaneous ICHs, “as CAA-related ICH has been reported to have a 7-fold increase for recurrent ICHs, compared with non–CAA-related ICH.”
 

Worrisome finding or false alarm?

In an accompanying editorial, Steven Greenberg, MD, PhD, with the department of neurology, Harvard Medical School, Boston, said there are “good reasons to treat the possibility of CAA transmission via blood transfusion seriously – and good reasons to remain skeptical, at least for the present.”

“Powerful” arguments in support of the findings include the robust study methodology and the “striking” similarity in results from the two registries, which argues against a chance finding. Another is the negative control with ischemic stroke as the outcome, which argues against unsuspected confounding-causing associations with all types of stroke, Dr. Greenberg noted.

Arguments for remaining “unconvinced” of the association center on the weakness of evidence for a plausible biological mechanism for the finding, he points out. Another is the short-time course of ICHs after blood transfusion, which is “quite challenging to explain,” Dr. Greenberg said. Nearly half of the ICHs among blood recipients occurred within 5 years of transfusion, which is “dramatically” faster than the 30- to 40-year interval reported between neurosurgical exposure to cadaveric tissue and first ICH, he added.

Another related “mechanistic reservation” is the plausibility that a transmissible species of amyloid-beta could travel from blood to brain in sufficient quantities to trigger advanced CAA or Alzheimer disease pathology, he wrote.

He added the current study leaves him “squarely at the corner of anxiety and skepticism.”

With more than 10 million units of blood transfused in the United States each year, even a modest increase in risk for future brain hemorrhages or dementia conferred by “an uncommon – but as of now undetectable – donor trait would represent a substantial public health concern,” Dr. Greenberg wrote.

“From the standpoint of scientific plausibility, however, even this well-conducted analysis is at risk of representing a false alarm,” he cautioned.

Looking ahead, Dr. Greenberg said one clear direction is independent replication, ideally with datasets in which donor and recipient dementia can be reliably ascertained to assess the possibility of Alzheimer’s disease as well as CAA transmissibility.

“The other challenge is for experimental biologists to consider the alternative possibility of transfusion-related acceleration of downstream steps in the CAA-ICH pathway, such as the vessel remodeling by which amyloid beta–laden vessels proceed to rupture and bleed.”

“The current study is not yet a reason for alarm, certainly not a reason to avoid otherwise indicated blood transfusion, but it is a strong call for more scientific digging,” Dr. Greenberg concluded.

The study was funded by grants from the Karolinska Institute, the Swedish Research Council, and Region Stockholm. Dr. Zhao and Dr. Greenberg report no relevant financial relationships.

A version of this article first appeared on Medscape.com.

New research hints at the possibility that cerebral amyloid angiopathy (CAA), a cause of spontaneous brain hemorrhage, can be transmitted via blood transfusion, raising the risk for spontaneous intracerebral hemorrhage (ICH) in transfusion recipients.

In an exploratory analysis, patients receiving red blood cell transfusions from donors who later developed multiple spontaneous ICHs, and were assumed to have CAA, were at a significantly increased risk of developing spontaneous ICH themselves.

“This may suggest a transfusion-transmissible agent associated with some types of spontaneous ICH, although the findings may be susceptible to selection bias and residual confounding, and further research is needed to investigate if transfusion transmission of CAA might explain this association,” the investigators noted.

“We do not think that the findings motivate a change in practice, and we should not let these results discourage otherwise indicated blood transfusion,” said lead author Jingcheng Zhao, MD, PhD, with Karolinska University Hospital Solna, Stockholm.

The study was published online  in the Journal of the American Medical Association.
 

Novel finding

Recent evidence suggests that CAA exhibits “prion-like” transmissivity, with reports of transmission through cadaveric pituitary hormone contaminated with amyloid-beta and tau protein, dura mater grafts, and possibly neurosurgical instruments.

CAA, which is characterized by the deposition of amyloid protein in the brain, is the second most common cause of spontaneous ICH. 

The researchers hypothesized that transfusion transmission of CAA may manifest through an increased risk for spontaneous ICH among transfusion recipients given blood from a donor with spontaneous ICH. To explore this hypothesis, they analyzed national registry data from Sweden and Denmark for ICH in recipients of red blood cell transfusion from donors who themselves had ICH over the years after their blood donations, with the assumption that donors with two or more ICHs would likely have CAA.

The cohort included nearly 760,000 individuals in Sweden (median age, 65 years; 59% women) and 330,000 in Denmark (median age, 64 years; 58% women), with a median follow-up of 5.8 and 6.1 years, respectively.

Receiving red blood cell transfusions from donors who later developed multiple spontaneous ICHs was associated with a greater than twofold increased risk of developing spontaneous ICH, compared with receiving a transfusion from donors without subsequent ICH (hazard ratio, 2.73; P < .001 in the Swedish cohort and HR, 2.32; P = .04 in the Danish cohort).

“The observed increased risk of spontaneous ICH associated with receiving a red blood cell transfusion from a donor who later developed multiple spontaneous ICHs, corresponding to a 30-year cumulative incidence difference of 2.3%, is a novel finding,” the researchers wrote.

There was no increase in post-transfusion ICH risk among recipients whose donors had a single post–blood-donation ICH.

The findings were robust to several of the sensitivity analyses.

A “negative” control analysis of post-transfusion ischemic stroke (instead of ICH) found no increased risk among recipients of blood from donors who had single or multiple ICHs.

This study provides “exploratory evidence of possible transfusion-transmission of a factor that causes ICHs, but more research is needed to confirm and to understand the mechanism,” said Dr. Zhao.

The researchers noted that they did not directly assess CAA but expect it would be more common among donors who develop multiple spontaneous ICHs, “as CAA-related ICH has been reported to have a 7-fold increase for recurrent ICHs, compared with non–CAA-related ICH.”
 

Worrisome finding or false alarm?

In an accompanying editorial, Steven Greenberg, MD, PhD, with the department of neurology, Harvard Medical School, Boston, said there are “good reasons to treat the possibility of CAA transmission via blood transfusion seriously – and good reasons to remain skeptical, at least for the present.”

“Powerful” arguments in support of the findings include the robust study methodology and the “striking” similarity in results from the two registries, which argues against a chance finding. Another is the negative control with ischemic stroke as the outcome, which argues against unsuspected confounding-causing associations with all types of stroke, Dr. Greenberg noted.

Arguments for remaining “unconvinced” of the association center on the weakness of evidence for a plausible biological mechanism for the finding, he points out. Another is the short-time course of ICHs after blood transfusion, which is “quite challenging to explain,” Dr. Greenberg said. Nearly half of the ICHs among blood recipients occurred within 5 years of transfusion, which is “dramatically” faster than the 30- to 40-year interval reported between neurosurgical exposure to cadaveric tissue and first ICH, he added.

Another related “mechanistic reservation” is the plausibility that a transmissible species of amyloid-beta could travel from blood to brain in sufficient quantities to trigger advanced CAA or Alzheimer disease pathology, he wrote.

He added the current study leaves him “squarely at the corner of anxiety and skepticism.”

With more than 10 million units of blood transfused in the United States each year, even a modest increase in risk for future brain hemorrhages or dementia conferred by “an uncommon – but as of now undetectable – donor trait would represent a substantial public health concern,” Dr. Greenberg wrote.

“From the standpoint of scientific plausibility, however, even this well-conducted analysis is at risk of representing a false alarm,” he cautioned.

Looking ahead, Dr. Greenberg said one clear direction is independent replication, ideally with datasets in which donor and recipient dementia can be reliably ascertained to assess the possibility of Alzheimer’s disease as well as CAA transmissibility.

“The other challenge is for experimental biologists to consider the alternative possibility of transfusion-related acceleration of downstream steps in the CAA-ICH pathway, such as the vessel remodeling by which amyloid beta–laden vessels proceed to rupture and bleed.”

“The current study is not yet a reason for alarm, certainly not a reason to avoid otherwise indicated blood transfusion, but it is a strong call for more scientific digging,” Dr. Greenberg concluded.

The study was funded by grants from the Karolinska Institute, the Swedish Research Council, and Region Stockholm. Dr. Zhao and Dr. Greenberg report no relevant financial relationships.

A version of this article first appeared on Medscape.com.