The impact of anti-inflammatory therapy on Parkinson's disease incidence: A retrospective cohort study.

Background: Previous research suggests shared pathophysiology between Parkinson's Disease (PD) and autoimmune disorders, with inflammation reduction as a potential PD intervention. The impact of anti-tumor necrosis factor (anti-TNF) and anti-interleukin (IL)-17 drugs on PD development has yielded conflicting results.

Objectives: The study investigated the association between PD incidence and immunosuppressive anti-inflammatory drugs in patients with autoimmune diseases (rheumatoid arthritis, ulcerative colitis, Crohn's disease, ankylosing spondylitis, psoriasis/psoriatic arthritis).

Methods: A retrospective study was conducted using data from 2014 to 2022 from the US Komodo Health claims database. Two cohorts of patients diagnosed with autoimmune diseases were designed: 1) exposed to biologic disease-modifying antirheumatic drugs (bDMARDS e.g., anti-TNF/anti-IL-17 drugs) and 2) absent such exposure. Person-time incidence rates of PD per 100 person-years (PY) and incidence rate ratios (IRRs) were calculated and covariate adjusted via Poisson regressions.

Results: Among 2,105,677 identified patients with autoimmune disease, 114,082 were treated with anti-TNF/anti-IL-17 and 1,991,595 were not. Unadjusted analyses indicated lower PD incidence in those treated with bDMARDscompared to the not treated (0.661 vs 0.949 per 100-PY; IRR 0.696 [95 % CI: 0.669-0.724]). Multivariate Poisson models comparing cohorts exposed to bDMARDs vs those lacking exposure resulted in significantly lower risk of PD (adjusted IRR 0.77 [95 % CI 0.74-0.80], p-value <0.0001). For patients exposed to anti-TNF or anti-IL-17 therapies, the IRRs were 0.77 (95 % CI 0.74-0.81) and 0.64 (95 % CI 0.52-0.80), respectively (p-values<0.001).

Conclusions: The results suggest that reduced systemic inflammation via anti-TNF or anti-IL-17 treatment may decrease PD risk in patients with autoimmune diseases.