Impact of Neuropsychiatric Symptoms on the Quality of Life of Subjects with Parkinson's Disease

Background: Neuropsychiatric symptoms in Parkinson's disease (PD) are frequent. Impact of neuropsychiatric symptoms on quality of life has recently become a relevant topic of research due to its potential to develop targeted therapies to improve quality of life. Objective: To determine the impact of neuropsychiatric symptoms in patients with PD using the Parkinson's Disease Questionnaire Short Form (PDQ-8). Methods: Consecutive patients with PD were evaluated with the Scale for Evaluation of Neuropsychiatric Disorders in Parkinson's disease (SEND-PD) and PDQ-8 scales separately. Association between neuropsychiatric symptoms and quality of life was explored using, means comparisons, correlation coefficients and multiple regression models. Results: A total of 492 patients were included for the study. Overall, 44.5% had psychotic symptoms, 76.5% had alterations on mood/apathy domains, and 27% had an impulse control disorder. All neuropsychiatric symptoms had an effect on the PDQ-8 with a moderate to large effect size. Correlation coefficients ranged from 0.17 to 0.63 between neuropsychiatric symptoms and quality of life (p < 0.001, in all cases). The regression model showed that mood/apathy alterations and impulse control disorders, along with MDS-UPDRS III accounted for 49.8% of variance in the PDQ-8 simplified index (F = 122.98; p < 0.001). Mood/apathy alterations showed the highest correlation coefficient (0.63, p < 0.001) and beta (0.53, p < 0.001). Conclusions: Both the presence and severity of neuropsychiatric symptoms, in particular mood/apathy alterations, had a significant impact on quality of life in subjects with PD.