van den Wildenberg, W. P.
Universiteit van Amsterdam, Amsterdam Center for the Study of Adaptive Control in Brain and Behaviour (ACACia), Psychology Department, Amsterdam, The Netherlands
Dopamine agonist treatment is associated with the emergence of impulse control disorder (ICD) in Parkinson’s disease (PD). Agonists preferentially alter mesocorticolimbic dopamine pathways, which modulate risk-taking behavior. We hypothesized that dopamine agonists would increase risk-taking behavior in PD, especially among a vulnerable subset of patients who developed ICD concomitant with dopamine agonist use. PD patients with agonist-induced ICD (PDICD; n=22) and PD controls without ICD (PD-C; n=19) performed a variant of the Balloon Analogue Risk Task (BART) in which participants allowed balloons to inflate to earn higher rewards while risking the chance that the balloon would pop. The probability that balloons would pop was manipulated to assess sensitivity to negative consequences. Patients were tested separately in “on” and in “off” dopamine agonist states. In the off dopamine agonist state, PD-ICD and PD-C groups risked a similar number of balloon inflations to earn rewards. In the on agonist state, PD-ICD risked significantly more balloon inflations than PD-C to obtain rewards. Both groups risked fewer balloon inflations when the risk of balloon popping was higher and on trials immediately following a popped balloon. PD patients with ICD show a propensity toward risky decisions when on their dopamine agonist medication. The increase in risktaking appears driven by efforts to obtain higher rewards rather than by a reduced sensitivity to the effects of negative consequences. These findings suggest that changes in risk processing as a result of dopamine agonist use may underlie clinical symptoms of ICD. Our results also add behavioral support to the emerging view that the clinical expression of ICD reflects converging genetic, environmental, and pharmacological influences on dopamine and mesocorticolimbic function.