Title: Inverse Association Between Parkinson’s Disease and Rheumatoid Arthritis: A Meta-analysis of Observational Studies (P11-17.004)
Authors: Theres Boby Alexander, Jamir Pitton Rissardo, Ana Leticia Fornari Caprara, and Ian M. Walker
Conference: 2026 AAN, Chicago, IL
Objective
To evaluate the association between Parkinson’s disease (PD) and rheumatoid arthritis (RA) using a systematic meta-analysis of observational studies.
Background
PD and RA are chronic disorders with distinct clinical phenotypes but overlapping immunological and inflammatory pathways. Clarifying this relationship is critical for understanding shared pathophysiology and identifying potential therapeutic targets.
Design/Methods
We systematically searched PubMed and Embase for observational studies reporting RA incidence in PD patients (PD→RA) or PD incidence in RA patients (RA→PD). Twelve studies met inclusion criteria (4 PD→RA; 8 RA→PD). Data were pooled using a binary outcome meta-analysis with the Mantel-Haenszel method under a random-effects model (DerSimonian-Laird estimator). Risk ratios (RR) with 95% confidence intervals (CI) were calculated. Between-study heterogeneity was assessed using τ², I², and Cochran’s Q test. Publication bias was evaluated using Egger’s regression, Begg’s rank correlation, and trim-and-fill analysis.
Results
The overall random-effects model showed no significant association (RR 0.99; 95% CI: 0.77 to 1.28; p = 0.95), with high heterogeneity (τ² = 0.15; I² = 95%). Subgroup analysis revealed non-significant association with PD and risk of RA (RR = 0.81; 95% CI: 0.48–1.35), as well as the association with RA and risk of PD (RR = 1.09; 95% CI: 0.79–1.50). Publication bias tests were non-significant (Egger’s p = 0.68; Begg’s p = 0.58), although trim-and-fill suggested one potentially missing study.
Conclusions
PD was not associated with RA risk, and RA was not linked to PD risk. Further studies are needed to elucidate possible association between RA and PD.
Citation
Alexander TB, Rissardo JP, Caprara AL, Walker IM. Inverse Association Between Parkinson’s Disease and Rheumatoid Arthritis: A Meta-analysis of Observational Studies (P11-17.004). Neurology 2026;106(11_suppl_1):861. doi: 10.1212/WNL.0000000000213156.
Figure 1. Forest plot of observational studies assessing bidirectional associations between Parkinson’s disease and rheumatoid arthritis, showing no significant overall relationship and substantial interstudy heterogeneity across subgroups.