No causal relationship between ankylosing spondylitis and Parkinson's disease: Insights from Mendelian randomization...

Retrospective cohort and cross-sectional studies have indicated an association between ankylosing spondylitis (AS) and Parkinson's disease (PD). However, owing the multitude of limitations, a consistent conclusion has not been determined. Furthermore, whether a causal relationship exists between these two diseases remains unclear.

We conducted a two-way Mendelian randomization (MR) analysis using genome-wide association study data. For patients with PD, we utilised data from the ieu-b-7 database, whereas for patients with AS, we employed the three databases with the largest sample sizes for a combined analysis. These databases included ebi-a-GCST005529, finn-b-M13 ANKYLOSPON, and finn-b-M13 ANKYLOSPON STRICT. Our primary method of analysis was inverse variance weighting (IVW), supplemented by four other effective methods, to comprehensively infer a potential causal relationship between AS and PD. Additionally, we conduct various sensitivity analyses to assess the robustness of our estimates.

Based on our IVW MR analysis, no significant causal relationship between AS and PD was observed (odds ratio [OR] = 1.01, 95 % confidence interval [CI] = 0.99-1.03, P = 0.26). Additionally, our reverse MR analysis found no evidence supporting a significant causal relationship between PD and AS (OR = 0.93, 95 % CI = 0.85-1.01, P = 0.068). These results were substantiated by comprehensive sensitivity analyses that indicated minimal bias in the causal estimates.

In contrast to numerous existing clinical studies, this study failed to provide evidence supporting a significant impact of AS on PD risk, or vice versa. Further investigations regarding the potential causal mechanisms linking AS and PD are warranted.