Apathy, a feeling of indifference or a general lack of interest and motivation to engage in activity, is one of the most common neuropsychiatric symptoms in Parkinson's disease (PD). The large variation in prevalence and the underlying pathophysiological processes remain unclear due to heterogeneous PD populations. The purpose of this study was to identify risk factors for apathy, the modification or treatment of which may be clinically relevant and improve quality of life and caregiver burden for patients with Parkinson's disease. Caucasian subjects with Parkinson's disease were included in the study. Baseline demographics, neurological deficit, medications taken, cognitive and neuropsychiatric status, and the polymorphisms in the brain-derived neurotrophic factor gene were assessed. Apathy was diagnosed in 53 (50.5%) patients. They were less educated (OR 0.76 CI 0.64-0.89; p = 0.001), more frequently depressed (OR 1.08 CI 1.01-1.15; p = 0.018), and less frequently treated with inhibitors of monoamine oxidase-B (MAOB-I) (OR 0.07 CI 0.01-0.69; p = 0.023). Although apathetic patients were more likely to carry the Met/Met genotype, differences in the brain-derived neurotrophic factor BDNF rs6265 polymorphism between apathetic and non-apathetic PD patients were not statistically significant in multivariate analysis. Some risk factors for apathy may be clinically modifiable. Further studies are needed to assess whether modeling modifiable apathy risk factors will affect the prevalence of this neuropsychiatric symptom in patients with Parkinson's disease.
Keywords: Parkinson’s disease; apathy; brain-derived neurotrophic factor; risk factors.