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, according to investigators.
Irisin, a hormone released by muscles during physical exercise, also negatively correlated with Clinical Dementia Rating Scale Sum of Boxes (CDR-SOB) in female patients, pointing to a sex-specific disease phenomenon, reported by co-lead authors Manuela Dicarlo, PhD, and Patrizia Pignataro, MSc, of the University of Bari “A. Moro,” Bari, Italy, and colleagues.
Regular physical exercise can slow cognitive decline in individuals at risk for or with Alzheimer’s disease, and irisin appears to play a key role in this process, the investigators wrote in Annals of Neurology. Previous studies have shown that increased irisin levels in the brain are associated with improved cognitive function and reduced amyloid beta levels, suggesting the hormone’s potential as a biomarker and therapeutic target for Alzheimer’s disease.
“Based on the protective effect of irisin in Alzheimer’s disease shown in animal and cell models, the goal of the present study was to investigate the levels of irisin in the biological fluids of a large cohort of patients biologically characterized according to the amyloid/tau/neurodegeneration (ATN) scheme of the National Institute on Aging–Alzheimer’s Association (NIA-AA),” Dr. Dicarlo and colleagues wrote. “We aimed to understand whether there may be variations of irisin levels across the disease stages, identified through the ATN system.”
Lower Levels of Irisin Seen in Patients With Alzheimer’s Disease
The study included 82 patients with Alzheimer’s disease, 44 individuals with mild cognitive impairment (MCI), and 20 with subjective memory complaints (SMC). Participants underwent comprehensive assessments, including neurological and neuropsychological exams, nutritional evaluations, MRI scans, and routine lab tests. Cognitive impairment severity was measured using the CDR-SOB and other metrics.
Blood and CSF samples were collected from all patients, the latter via lumbar puncture. These samples were analyzed for irisin levels and known Alzheimer’s disease biomarkers, including Abeta42, total tau (t-tau), and hyperphosphorylated tau (p-tau).
Mean CSF irisin levels were significantly lower among patients with Alzheimer’s disease than those with SMC (0.80 vs 1.23 pg/mL; P < .0001), and among those with MCI vs SMC (0.95 vs 1.23 pg/mL; P = .046). Among patients with Alzheimer’s disease, irisin levels were significantly lower among women than men (0.70 vs 0.96 pg/mL; P = .031).
Further analyses revealed positive correlations between CSF irisin level and Abeta42 in both males (r = 0.262; P < 005) and females (r = 0.379; P < .001). Conversely, in female patients, a significant negative correlation was found between CSF irisin level and CDR-SOB score (r = −0.234; P < .05).
Although a negative trend was observed between CSF irisin and total tau (t-tau) in the overall patient population (r = −0.144; P = 0.082), and more notably in female patients (r = −0.189; P = 0.084), these results were not statistically significant.
Plasma irisin levels were not significantly correlated with any of the other biomarkers.
Clinical Implications
This study “verifies that irisin levels do have a relationship to the Alzheimer’s disease process,” said Dylan Wint, MD, director of Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas.
In a written comment, Dr. Wint speculated that measuring irisin levels could theoretically help individualize physical exercise routines designed to combat cognitive decline.
“For example, maybe someone who is exercising but has a low irisin level would need to change the type of exercise they’re doing in order to optimally protect their brain health,” he said. “Or maybe they won’t get the same benefits for brain health as someone whose irisin shoots up every time they walk a flight of stairs.”
It’s “near-impossible to tell,” however, if irisin will be employed in clinical trials or real-world practice, he added.
“I don’t see this being a highly useful serum biomarker for Alzheimer’s disease itself because other serum biomarkers are so far ahead and have more face validity,” Dr. Wint said.
The route of collection could also cause challenges.
“In the United States, CSF-based biomarkers can be a difficult sell, especially for serial testing,” Dr. Wint said. “But we have usable serum biomarkers for Alzheimer’s disease only because we have had CSF biomarkers against which to evaluate them. They may develop a way to evaluate this in the serum.”
Dr. Dicarlo and colleagues suggested that more work is needed to determine the ultimate value of irisin measurement.“The true ability of irisin to represent a biomarker of disease progression and severity remains to be further investigated,” they concluded. “However, our findings might offer interesting perspectives toward the potential role of irisin in the modulation of AD pathology and can guide the exploration of medication targeting the irisin system.”
The study was supported by Regione Puglia and CNR for Tecnopolo per la Medicina di Precisione, CIREMIC, the University of Bari, and Next Generation EU. The investigators and Dr. Wint disclosed no conflicts of interest.
, according to investigators.
Irisin, a hormone released by muscles during physical exercise, also negatively correlated with Clinical Dementia Rating Scale Sum of Boxes (CDR-SOB) in female patients, pointing to a sex-specific disease phenomenon, reported by co-lead authors Manuela Dicarlo, PhD, and Patrizia Pignataro, MSc, of the University of Bari “A. Moro,” Bari, Italy, and colleagues.
Regular physical exercise can slow cognitive decline in individuals at risk for or with Alzheimer’s disease, and irisin appears to play a key role in this process, the investigators wrote in Annals of Neurology. Previous studies have shown that increased irisin levels in the brain are associated with improved cognitive function and reduced amyloid beta levels, suggesting the hormone’s potential as a biomarker and therapeutic target for Alzheimer’s disease.
“Based on the protective effect of irisin in Alzheimer’s disease shown in animal and cell models, the goal of the present study was to investigate the levels of irisin in the biological fluids of a large cohort of patients biologically characterized according to the amyloid/tau/neurodegeneration (ATN) scheme of the National Institute on Aging–Alzheimer’s Association (NIA-AA),” Dr. Dicarlo and colleagues wrote. “We aimed to understand whether there may be variations of irisin levels across the disease stages, identified through the ATN system.”
Lower Levels of Irisin Seen in Patients With Alzheimer’s Disease
The study included 82 patients with Alzheimer’s disease, 44 individuals with mild cognitive impairment (MCI), and 20 with subjective memory complaints (SMC). Participants underwent comprehensive assessments, including neurological and neuropsychological exams, nutritional evaluations, MRI scans, and routine lab tests. Cognitive impairment severity was measured using the CDR-SOB and other metrics.
Blood and CSF samples were collected from all patients, the latter via lumbar puncture. These samples were analyzed for irisin levels and known Alzheimer’s disease biomarkers, including Abeta42, total tau (t-tau), and hyperphosphorylated tau (p-tau).
Mean CSF irisin levels were significantly lower among patients with Alzheimer’s disease than those with SMC (0.80 vs 1.23 pg/mL; P < .0001), and among those with MCI vs SMC (0.95 vs 1.23 pg/mL; P = .046). Among patients with Alzheimer’s disease, irisin levels were significantly lower among women than men (0.70 vs 0.96 pg/mL; P = .031).
Further analyses revealed positive correlations between CSF irisin level and Abeta42 in both males (r = 0.262; P < 005) and females (r = 0.379; P < .001). Conversely, in female patients, a significant negative correlation was found between CSF irisin level and CDR-SOB score (r = −0.234; P < .05).
Although a negative trend was observed between CSF irisin and total tau (t-tau) in the overall patient population (r = −0.144; P = 0.082), and more notably in female patients (r = −0.189; P = 0.084), these results were not statistically significant.
Plasma irisin levels were not significantly correlated with any of the other biomarkers.
Clinical Implications
This study “verifies that irisin levels do have a relationship to the Alzheimer’s disease process,” said Dylan Wint, MD, director of Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas.
In a written comment, Dr. Wint speculated that measuring irisin levels could theoretically help individualize physical exercise routines designed to combat cognitive decline.
“For example, maybe someone who is exercising but has a low irisin level would need to change the type of exercise they’re doing in order to optimally protect their brain health,” he said. “Or maybe they won’t get the same benefits for brain health as someone whose irisin shoots up every time they walk a flight of stairs.”
It’s “near-impossible to tell,” however, if irisin will be employed in clinical trials or real-world practice, he added.
“I don’t see this being a highly useful serum biomarker for Alzheimer’s disease itself because other serum biomarkers are so far ahead and have more face validity,” Dr. Wint said.
The route of collection could also cause challenges.
“In the United States, CSF-based biomarkers can be a difficult sell, especially for serial testing,” Dr. Wint said. “But we have usable serum biomarkers for Alzheimer’s disease only because we have had CSF biomarkers against which to evaluate them. They may develop a way to evaluate this in the serum.”
Dr. Dicarlo and colleagues suggested that more work is needed to determine the ultimate value of irisin measurement.“The true ability of irisin to represent a biomarker of disease progression and severity remains to be further investigated,” they concluded. “However, our findings might offer interesting perspectives toward the potential role of irisin in the modulation of AD pathology and can guide the exploration of medication targeting the irisin system.”
The study was supported by Regione Puglia and CNR for Tecnopolo per la Medicina di Precisione, CIREMIC, the University of Bari, and Next Generation EU. The investigators and Dr. Wint disclosed no conflicts of interest.
, according to investigators.
Irisin, a hormone released by muscles during physical exercise, also negatively correlated with Clinical Dementia Rating Scale Sum of Boxes (CDR-SOB) in female patients, pointing to a sex-specific disease phenomenon, reported by co-lead authors Manuela Dicarlo, PhD, and Patrizia Pignataro, MSc, of the University of Bari “A. Moro,” Bari, Italy, and colleagues.
Regular physical exercise can slow cognitive decline in individuals at risk for or with Alzheimer’s disease, and irisin appears to play a key role in this process, the investigators wrote in Annals of Neurology. Previous studies have shown that increased irisin levels in the brain are associated with improved cognitive function and reduced amyloid beta levels, suggesting the hormone’s potential as a biomarker and therapeutic target for Alzheimer’s disease.
“Based on the protective effect of irisin in Alzheimer’s disease shown in animal and cell models, the goal of the present study was to investigate the levels of irisin in the biological fluids of a large cohort of patients biologically characterized according to the amyloid/tau/neurodegeneration (ATN) scheme of the National Institute on Aging–Alzheimer’s Association (NIA-AA),” Dr. Dicarlo and colleagues wrote. “We aimed to understand whether there may be variations of irisin levels across the disease stages, identified through the ATN system.”
Lower Levels of Irisin Seen in Patients With Alzheimer’s Disease
The study included 82 patients with Alzheimer’s disease, 44 individuals with mild cognitive impairment (MCI), and 20 with subjective memory complaints (SMC). Participants underwent comprehensive assessments, including neurological and neuropsychological exams, nutritional evaluations, MRI scans, and routine lab tests. Cognitive impairment severity was measured using the CDR-SOB and other metrics.
Blood and CSF samples were collected from all patients, the latter via lumbar puncture. These samples were analyzed for irisin levels and known Alzheimer’s disease biomarkers, including Abeta42, total tau (t-tau), and hyperphosphorylated tau (p-tau).
Mean CSF irisin levels were significantly lower among patients with Alzheimer’s disease than those with SMC (0.80 vs 1.23 pg/mL; P < .0001), and among those with MCI vs SMC (0.95 vs 1.23 pg/mL; P = .046). Among patients with Alzheimer’s disease, irisin levels were significantly lower among women than men (0.70 vs 0.96 pg/mL; P = .031).
Further analyses revealed positive correlations between CSF irisin level and Abeta42 in both males (r = 0.262; P < 005) and females (r = 0.379; P < .001). Conversely, in female patients, a significant negative correlation was found between CSF irisin level and CDR-SOB score (r = −0.234; P < .05).
Although a negative trend was observed between CSF irisin and total tau (t-tau) in the overall patient population (r = −0.144; P = 0.082), and more notably in female patients (r = −0.189; P = 0.084), these results were not statistically significant.
Plasma irisin levels were not significantly correlated with any of the other biomarkers.
Clinical Implications
This study “verifies that irisin levels do have a relationship to the Alzheimer’s disease process,” said Dylan Wint, MD, director of Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas.
In a written comment, Dr. Wint speculated that measuring irisin levels could theoretically help individualize physical exercise routines designed to combat cognitive decline.
“For example, maybe someone who is exercising but has a low irisin level would need to change the type of exercise they’re doing in order to optimally protect their brain health,” he said. “Or maybe they won’t get the same benefits for brain health as someone whose irisin shoots up every time they walk a flight of stairs.”
It’s “near-impossible to tell,” however, if irisin will be employed in clinical trials or real-world practice, he added.
“I don’t see this being a highly useful serum biomarker for Alzheimer’s disease itself because other serum biomarkers are so far ahead and have more face validity,” Dr. Wint said.
The route of collection could also cause challenges.
“In the United States, CSF-based biomarkers can be a difficult sell, especially for serial testing,” Dr. Wint said. “But we have usable serum biomarkers for Alzheimer’s disease only because we have had CSF biomarkers against which to evaluate them. They may develop a way to evaluate this in the serum.”
Dr. Dicarlo and colleagues suggested that more work is needed to determine the ultimate value of irisin measurement.“The true ability of irisin to represent a biomarker of disease progression and severity remains to be further investigated,” they concluded. “However, our findings might offer interesting perspectives toward the potential role of irisin in the modulation of AD pathology and can guide the exploration of medication targeting the irisin system.”
The study was supported by Regione Puglia and CNR for Tecnopolo per la Medicina di Precisione, CIREMIC, the University of Bari, and Next Generation EU. The investigators and Dr. Wint disclosed no conflicts of interest.
FROM ANNALS OF NEUROLOGY