Decision-making process in Parkinson's disease: a systematic review

Background: Parkinson's disease (PD) is a common neurodegenerative disorder affecting 2-3% of the elderly population, and it is characterized by a loss of dopamine-producing neurons in the substantia nigra. The mainly described symptoms affect the motor system, but there is increasing awareness of non-motor symptoms, such as addictions and decision-making (DM) impairment. DM is a cognitive process that drives us in everyday life activities and helps us to choose an option when faced with multiple alternatives. Methods: The present work critically examined the studies that evaluated the difference in DM performance, using different cognitive tests, between subjects with Parkinson's disease and healthy controls. The systematic review was conducted according to the PRISMA Statement. Results: Thirty-nine studies were identified. The results highlighted that decision-making in ambiguous and risky situations is impaired in individuals with Parkinson's disease compared to the healthy population. Clinical subjects have a higher propensity to take risks, more disadvantageous choices, poorer performance, and a lower ability to learn adequate strategies. Accordingly, the non-motor symptom involving DM as high cognitive functions influencing daily activities should be considered in the clinical assessment of PD.