To assess the participation of minority Parkinson’s disease (PD) patients in clinical trials evaluating the treatment of neuropsychiatric symptoms in PD, and to explore the underlying reasons for the observed under-representation.

There are consistent racial and ethnic disparities reported in the diagnosis and treatment of neuropsychiatric symptoms in PD. Additionally, the enrollment of underrepresented minorities in PD trials has historically fallen below their proportional prevalence, lessening the generalizability of therapeutic discoveries for people with PD.

Overall, 756 studies were identified. After removal of duplicate reports, animal studies and non-relevant studies by title or abstract review, 85 articles remained. A total of 72 studies, representing 9122 patients met all criteria and were included. Only 11 (15.2%) trials reported race/ethnicity of study participants. Of those, white patients represented 78.3% of all enrolled patients, while other ethnicities represented 21.7%. Only two studies (2.7%) reported the percentage of enrolled African Americans (0.05% of all enrolled patients) and Hispanics (0.6% of all enrolled patients).

The pooled analysis found that only a small percentage of studies reported race and ethnicity. Consistent with previous studies and meta-analyses in other specialties, there was an overwhelming predominance of white patients. We plan to further investigate the reasons for this discrepancy in order to develop strategies for improving rates of minority enrollment in PD trials.