Effects of Dopamine on Reward Learning in Parkinson’s Patients with Impulse Control Disorders

Abstract

This study investigated how dopamine agonist medication differentially affects reward learning in Parkinson’s patients with and without Impulse Control Disorders (ICDs). We tested 16 patients (8 female, 5 with ICDs, mean age = 62.1) on and off of their dopamine agonist medication using a dynamic foraging task with probability reversals. We hypothesized that patients with ICDs, but not patients without ICDs, would have worse task performance on medication than off medication. Paired samples t-tests confirmed our hypothesis – that task performance was significantly worse on medication than off for ICD patients [t(4) = 2.86, p = .046], but not for non-ICD patients [t(10) = 1.67, p = .126]. This suggests that ICD patients are more vulnerable to medication effects that cause aberrant reward learning, which could be the basis of their impulse control behaviors.