DBS May Improve Impulse Control in Patients With Parkinson’s Disease

LAS VEGAS—Dopamine agonists can reduce the tremor, stiffness, and slowness associated with Parkinson’s disease, but they also may contribute toward the development of impulse-control disorders. Deep brain stimulation (DBS) may be an effective way to control these disorders, according to research presented at the 18th Annual Meeting of the North American Neuromodulation Society.

Heather C. Smith, a medical student at Albany Medical College in New York, and colleagues examined 16 patients with Parkinson’s disease who subsequently received bilateral subthalamic nucleus DBS delivered via an implanted device. All patients responded to the Questionnaire for Impulsive–Compulsive Disorders in Parkinson’s Disease-Rating Scale (QUIP-RS) before undergoing surgery. The investigators administered the QUIP-RS to the participants again at six months and one year after surgery.

In addition, the researchers examined sensorimotor gating among the participants to determine which people are more likely to develop impulse-control disorders. Eight patients completed the Balloon Analog Risk Task (BART) and auditory prepulse inhibition testing.

Of the 16 patients, 10 were male. The study population’s mean age was approximately 58. Mean disease duration before surgical intervention was approximately 12 years. Ten of the 16 patients received dopamine agonists.

Post-Implant Improvements
A total of 12 patients (75%) had significant improvement in impulse-control disorders after DBS implantation, as measured by QUIP-RS. Four people had nonsignificant increases in impulsivity after implantation. For the good responders to DBS, the most significant reductions were in hypersexual behavior and binge eating.

Gender, age, age of onset, disease duration, and decrease in levodopa equivalence dose did not differ significantly between the 12 responders and the four nonresponders. Lead locations and stimulation parameters also were similar between groups. Two of the four poor responders, however, had an increase in dopamine agonist dose after surgery. The third poor responder had a history of cocaine abuse, and the fourth poor responder had acute abdominal pain that only responded well to levodopa. These factors might have influenced the four patients’ response to DBS, said Ms. Smith.

Increased impulsivity on BART correlated with impaired sensorimotor gating, as measured by prepulse inhibition testing. This result is consistent with those of previous studies in patients without Parkinson’s disease. The latter studies showed an association between impaired response on prepulse inhibition testing and increased distractibility. The current study is the first to indicate that impaired prepulse inhibition could contribute to the development of impulse-control disorders among patients with Parkinson’s disease, said Ms. Smith.

—Erik Greb

LAS VEGAS—Dopamine agonists can reduce the tremor, stiffness, and slowness associated with Parkinson’s disease, but they also may contribute toward the development of impulse-control disorders. Deep brain stimulation (DBS) may be an effective way to control these disorders, according to research presented at the 18th Annual Meeting of the North American Neuromodulation Society.

Heather C. Smith, a medical student at Albany Medical College in New York, and colleagues examined 16 patients with Parkinson’s disease who subsequently received bilateral subthalamic nucleus DBS delivered via an implanted device. All patients responded to the Questionnaire for Impulsive–Compulsive Disorders in Parkinson’s Disease-Rating Scale (QUIP-RS) before undergoing surgery. The investigators administered the QUIP-RS to the participants again at six months and one year after surgery.

In addition, the researchers examined sensorimotor gating among the participants to determine which people are more likely to develop impulse-control disorders. Eight patients completed the Balloon Analog Risk Task (BART) and auditory prepulse inhibition testing.

Of the 16 patients, 10 were male. The study population’s mean age was approximately 58. Mean disease duration before surgical intervention was approximately 12 years. Ten of the 16 patients received dopamine agonists.

Post-Implant Improvements
A total of 12 patients (75%) had significant improvement in impulse-control disorders after DBS implantation, as measured by QUIP-RS. Four people had nonsignificant increases in impulsivity after implantation. For the good responders to DBS, the most significant reductions were in hypersexual behavior and binge eating.

Gender, age, age of onset, disease duration, and decrease in levodopa equivalence dose did not differ significantly between the 12 responders and the four nonresponders. Lead locations and stimulation parameters also were similar between groups. Two of the four poor responders, however, had an increase in dopamine agonist dose after surgery. The third poor responder had a history of cocaine abuse, and the fourth poor responder had acute abdominal pain that only responded well to levodopa. These factors might have influenced the four patients’ response to DBS, said Ms. Smith.

Increased impulsivity on BART correlated with impaired sensorimotor gating, as measured by prepulse inhibition testing. This result is consistent with those of previous studies in patients without Parkinson’s disease. The latter studies showed an association between impaired response on prepulse inhibition testing and increased distractibility. The current study is the first to indicate that impaired prepulse inhibition could contribute to the development of impulse-control disorders among patients with Parkinson’s disease, said Ms. Smith.

—Erik Greb

LAS VEGAS—Dopamine agonists can reduce the tremor, stiffness, and slowness associated with Parkinson’s disease, but they also may contribute toward the development of impulse-control disorders. Deep brain stimulation (DBS) may be an effective way to control these disorders, according to research presented at the 18th Annual Meeting of the North American Neuromodulation Society.

Heather C. Smith, a medical student at Albany Medical College in New York, and colleagues examined 16 patients with Parkinson’s disease who subsequently received bilateral subthalamic nucleus DBS delivered via an implanted device. All patients responded to the Questionnaire for Impulsive–Compulsive Disorders in Parkinson’s Disease-Rating Scale (QUIP-RS) before undergoing surgery. The investigators administered the QUIP-RS to the participants again at six months and one year after surgery.

In addition, the researchers examined sensorimotor gating among the participants to determine which people are more likely to develop impulse-control disorders. Eight patients completed the Balloon Analog Risk Task (BART) and auditory prepulse inhibition testing.

Of the 16 patients, 10 were male. The study population’s mean age was approximately 58. Mean disease duration before surgical intervention was approximately 12 years. Ten of the 16 patients received dopamine agonists.

Post-Implant Improvements
A total of 12 patients (75%) had significant improvement in impulse-control disorders after DBS implantation, as measured by QUIP-RS. Four people had nonsignificant increases in impulsivity after implantation. For the good responders to DBS, the most significant reductions were in hypersexual behavior and binge eating.

Gender, age, age of onset, disease duration, and decrease in levodopa equivalence dose did not differ significantly between the 12 responders and the four nonresponders. Lead locations and stimulation parameters also were similar between groups. Two of the four poor responders, however, had an increase in dopamine agonist dose after surgery. The third poor responder had a history of cocaine abuse, and the fourth poor responder had acute abdominal pain that only responded well to levodopa. These factors might have influenced the four patients’ response to DBS, said Ms. Smith.

Increased impulsivity on BART correlated with impaired sensorimotor gating, as measured by prepulse inhibition testing. This result is consistent with those of previous studies in patients without Parkinson’s disease. The latter studies showed an association between impaired response on prepulse inhibition testing and increased distractibility. The current study is the first to indicate that impaired prepulse inhibition could contribute to the development of impulse-control disorders among patients with Parkinson’s disease, said Ms. Smith.

—Erik Greb