To Örebro University

Objective: To examine the association between microscopic colitis (MC) and Parkinson’s disease (PD) risk.

Background: Gastrointestinal inflammation has been linked with PD. MC is a chronic intestinal inflammatory disease; however, its relationship with PD is unknown.

Design/Methods: A population-based matched cohort study was conducted to estimate the association between MC and incident PD diagnosis using Cox regression models. An exposed cohort of 12,609 MC patients diagnosed 1990–2017 and aged ≥35 years at diagnosis was identified from the Epidemiology Strengthened by histoPathology Reports in Sweden cohort (ESPRESSO). Two unexposed cohorts were compared to: a population cohort comprising 58,879 MC-free individuals randomly selected from the population and 1:5 matched to each MC patient by age, sex, year of biopsy and county of residence at the time of biopsy; and a sibling cohort (NMC/NSibling=6,281/12,351) including all siblings of the MC patients. Follow-up was from the date of biopsy until December 31st 2016 at latest.

Results: During a mean follow-up of ~7 years, we identified 449 incident PD diagnoses among the MC patients and their matched population cohort. The overall PD risk was 76% higher among MC versus MC-free individuals; but the association attenuated substantially during follow-up. In the time-varying effects model, PD risk was 3.45-fold (95% CI: 2.42, 4.93) higher during the first 2 years after biopsy and 1.80-fold (95% CI: 1.23, 2.64) higher during the following 3 years among MC versus MC-free individuals, but was not differential beyond 5 years after biopsy (hazard ratio=1.03; 95% CI: 0.68, 1.54). This temporal pattern of MC-PD associations persisted in sibling analyses. Using a matched case-control design, we also observed a higher prevalence of prior PD diagnosis among MC patients than the matched MC-free individuals (odds ratio=3.46; 95% CI: 2.91, 4.12).

Conclusions: Our findings suggest that MC may not be a risk factor, but rather a comorbidity or complication of PD.