Altruism in Parkinson's Disease

Objective: Reward-based decision-making is a growing area of research in Parkinson's disease (PD), a disorder characterized by alterations in dopamine and cortico-striatal circuits. While reward is typically operationalized as a gain, altruistic decisions also engage the reward system in fMRI studies. Although altruism comes at a cost, individuals may be motivated by the social reward associated with benefitting another. At present, it is unclear how PD affects altruism because both increased egoistic tendencies and increased generosity have been documented. Method: To address this, 32 individuals with PD and 32 age-matched healthy controls completed two tasks of implicit and explicit altruism. First, in an intertemporal choice task, participants chose between a smaller immediate or larger later outcome. Outcome types included gains, losses, and donations, and an implicit altruism measure was derived. Second, participants completed two versions of the dictator game, which assesses nonreciprocal giving and yields an explicit measure of altruism. Results: Patients and controls showed similar altruism in the intertemporal choice task and in a dictator game for a charity, but patients were more generous than controls in the dictator game in which the recipient was a stranger. Among patients, altruism measures were moderated by laterality of hemispheric burden and medication type. Conclusions: This study was the first to examine altruistic decision-making in PD patients using both implicit and explicit measures. PD patients were neither overly generous nor egoistic in their decisions, although some disease and treatment characteristics may have a modest association with altruism in PD. Key Points Question: How does advanced PD and its treatment relate to implicit and explicit financial measures of altruism? Findings: PD patients make similar altruistic decisions as controls when donating. PD patients gave more to strangers on a dictator game task. Certain disease characteristics of PD patients relate to altruism. Importance: Intact financial decisions offer reassurance to PD patients and their caregivers. Next Steps: Deeper investigation into the relationships between characteristics of PD patients and prosocial motivation is an interesting avenue for future research, with translational potential in domains such as health, social functioning, and financial competence.