Most people know that patients with Parkinson’s disease are impaired in their movements. But it is less well known that patients also suffer from mental problems: they find it difficult to do multiple things at the same time or to plan ahead for instance. The dopaminergic medication that they take helps them move and think. Unfortunately, in some patients, the same medication can also contribute to worrisome impulsive behavior with respect to reward, such as pathological gambling or compulsive shopping.