Altruism in Parkinson's disease

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. 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. 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. 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. (PsycInfo Database Record (c) 2021 APA, all rights reserved).