COVID-19 and Parkinson's disease: a single-center study and Mendelian randomization study.

To investigate the association between COVID-19 and Parkinson's disease (PD) via a single-center study and a Mendelian randomization (MR) study. A questionnaire-based survey was conducted among PD patients at a single center from December 7, 2022, to March 10, 2023. Logistic regression analysis was performed to identify the infection-related risk factors. Subsequently, bidirectional two-sample Mendelian randomization was employed to explore the association between COVID-19 and PD. In the cross-sectional analysis, it was found that the prevalence of COVID-19 infection in PD patients was 65.7%. Forty-eight (35.3%) PD patients experienced exacerbation of motor symptoms following COVID-19 infection. Long PD disease duration (≥ 10 years) (OR: 3.327, P = 0.045) and long time since last vaccination (> 12 m) (OR: 4.916, P = 0.035) were identified as significant risk factors related to infection. The MR analysis results supported that PD increases the COVID-19 susceptibility (β = 0.081, OR = 1.084, P = 0.006). However, the MR analysis showed that PD did not increases the COVID-19 severity and hospitalization, and no significant association of COVID-19 on PD was observed. The findings from this cross-sectional study suggest that individuals with PD may experience worsened motor symptoms following COVID-19 infection. Long disease duration (≥10 years) and long time since last vaccination (> 12 m) are identified as important risk factors for infection in these patients. Furthermore, our MR study provides evidence supporting an association between PD and COVID-19 susceptibility.