Reckless Generosity, Parkinson's Disease and Dopamine: A Case Series and Literature Review

BACKGROUND: Impulse control disorders (ICDs) are a frequent side effect of dopamine replacement therapy (DRT) in Parkinson's disease (PD). Reckless generosity might expand the spectrum of known ICDs. CASES: Over 18 months, we encountered three PD patients exhibiting reckless generosity under DRT, leading to disastrous financial and social consequences. LITERATURE REVIEW: Except for another case series describing reckless generosity in three PD patients, only one study has examined generosity in PD patients; with findings suggesting that PD patients with ICDs are less sensitive to the aversive aspects of the lack of reciprocation in social settings. Studies with healthy individuals suggest that increased availability of dopamine might reduce social discounting and promote egalitarian behavior, and thereby increase generous behavior towards strangers. Genetic studies show that polymorphisms in dopamine D4 receptors influence generous behavior. CONCLUSIONS: Reckless generosity in PD patients with DRT might be underreported and should therefore be carefully be screened for by clinicians. A potential mechanism underlying this ICD‐related behavior might be a sensitization of the mesolimbic and mesocortical dopaminergic system, leading to reduced social discounting and maladaptive reward‐learning. Further research is needed to investigate the prevalence and underlying mechanisms of reckless generosity in PD patients.