Association Between Upper Respiratory Tract Infections and Parkinson’s Disease in Korean Populations: A Nested Case-Control Study Using a National Health Screening Cohort

Although epidemiological studies have suggested associations between infections and Parkinson’s disease (PD), only few have explored the relationship between upper respiratory tract infections (URIs) and PD, apart from coronavirus disease 2019 (COVID-19). This study investigated whether a history of URI was associated with PD diagnosis in Korean individuals aged ≥40 years using data from the Korean National Health Insurance Service National Sample Cohort. A total of 5,844 patients with PD were identified and matched with 23,376 control participants at a 1:4 ratio based on age, sex, income, and geographical region. Multiple logistic regression models were used to estimate the association between URI history and PD, adjusting for smoking status, alcohol consumption, obesity, blood pressure, fasting blood glucose, total cholesterol, and comorbidity scores. Individuals with URI history within 1 year (≥1, ≥2, or ≥3 episodes) had significantly lower odds of PD diagnosis than matched controls (adjusted odds ratio [aOR]: 0.93, 95% confidence interval [CI]: 0.88–0.97, aOR: 0.91, 95% CI: 0.87–0.96 and aOR: 0.92, 95% CI: 0.87–0.98, respectively). No significant association was observed for URI history within 2 years. These findings suggest a potential inverse relationship between recent URI and PD development, warranting further investigation into underlying mechanisms.