At risk for pathological gambling.

I had not realized that treating Parkinson's disease or restless legs syndrome with dopamine agonists (mimics or enhancers) has been associated with impulse control disorders and pathological gambling. Abler et al. look at correlative changes in the brain:

We scanned 12 female restless leg syndrome patients without a history of pathological gambling. All patients were scanned twice: once whilst taking their regular medication with low dose dopamine receptor agonists and once after a washout phase interval. They performed an established gambling game task involving expectation and receipt or omission of monetary rewards at different levels of probabilities. Upon expectation of rewards, reliable ventral striatal activation was detected only when patients were on, but not when patients were off medication....Chronic dopamine receptor agonist medication changed the neural signalling of reward expectation predisposing the dopaminergic reward system to mediate an increased appetitive drive.