Supplementary Material for: The Impact of Parkinson Disease Psychosis on Caregiver Burden: A Systematic Literature Review

Introduction: Studies of Parkinson’s disease (PD) caregiver stress have examined many contributing factors, but a clear understanding of the impact of Parkinson's disease psychosis (PDP) on caregiver burden has been difficult to ascertain from existing evidence. The evidence has been collected primarily in small, heterogeneous studies that do not lend themselves to meta-analysis.
Objective: To understand current evidence on the association between PDP and caregiver burden despite the heterogeneity of populations studied and methods used.
Methods: Following PRISMA guidelines, PubMed, Embase, and ClinicalTrials.gov were searched from inception through April 1, 2025, for English-language articles using predefined search terms. Eligible original research included individuals with PD, assessment of psychosis symptoms, defined caregivers, and evaluation of the association between psychosis and caregiver burden. Data was extracted independently, and study quality was assessed using the Newcastle Ottawa Scale. The exposure was PDP, and the outcome was caregiver burden.
Results: Twenty-six articles met inclusion criteria. Most studies enrolled fewer than 100 participants; 9 of these (34.6%) had low risk of bias. Psychosis symptoms were assessed via validated questionnaires in 17 studies, self-report in 7, and unspecified methods in 2. Definitions of caregiver varied, with 4 studies including paid caregivers. Among 10 studies adjusting for confounders, 6 (60%) reported a significant positive association between PDP symptoms and caregiver burden. Of the 4 multivariate studies without a significant association, 3 found positive relationships between other patient psychiatric symptoms and this burden.
Conclusion: While the quality of research is variable and studies include an array of different population definitions and measurement approaches, higher-quality studies indicate PDP is associated with greater caregiver burden. To facilitate the well-being of patients with PDP and their caregivers, it is important to identify and address the specific caregiver challenges due to psychosis symptoms in PD.