Parkinson's Disease Research Today is a free monthly online journal that collates and summarizes the latest research about Parkinson's Disease, including details on symptoms, treatment, genetics, medication.

Hold your horses: impulsivity, deep brain stimulation, and medication in parkinsonism.

Frank MJ, Samanta J, Moustafa AA, Sherman SJ

Department of Psychology and Program in Neuroscience, University of Arizona, Tucson, AZ 85721, USA. mfrank@u.arizona.edu

Deep brain stimulation (DBS) of the subthalamic nucleus markedly improves the motor symptoms of Parkinson's disease, but causes cognitive side effects such as impulsivity. We showed that DBS selectively interferes with the normal ability to slow down when faced with decision conflict. While on DBS, patients actually sped up their decisions under high-conflict conditions. This form of impulsivity was not affected by dopaminergic medication status. Instead, medication impaired patients' ability to learn from negative decision outcomes. These findings implicate independent mechanisms leading to impulsivity in treated Parkinson's patients and were predicted by a single neurocomputational model of the basal ganglia.

Published 23 November 2007 in Science, 318(5854): 1309-12.
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