Association of allergic disease with Parkinson's disease: A nationally representative retrospective cohort study

The association of allergic diseases such as allergic rhinitis, asthma, and atopic dermatitis with Parkinson's disease (PD) risk is yet unclear. In the few preceding studies, a short follow-up duration was followed for a relatively small study population, and lifestyle behaviors were not adjusted for. Therefore, there is a need for large-scale observation studies on the association of allergic disease with PD risk after considering lifestyle behaviors.

The study population consisted of 398,936 participants aged 40 years or older who underwent health screening before 1 January 2005 from the Korean National Health Insurance Service database. Starting from 1 January 2005, all participants were followed up until the date of PD event, death, or 31 December 2019. The adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for the risk of PD were calculated using multivariable Cox proportional hazards regression.

Compared to non-allergic disease participants, allergic disease patients had a higher risk for PD (aHR 1.18, 95% CI 1.07-1.30) and especially, allergic rhinitis patients had a higher risk for PD (aHR 1.14, 95% CI 1.00-1.29). Allergic disease was associated with a higher risk for PD (aHR 1.24, 95% CI 1.01-1.52) among participants who were never smokers, did not consume alcohol, and exercised regularly.

Allergic rhinitis was associated with a higher risk for PD compared to participants without allergic rhinitis. This risk-increasing association of allergic rhinitis with PD was preserved even among people with healthy lifestyle behaviors.