Statin use and risk of Parkinson's disease among older adults in Japan: a nested case-control study using the Longevity Improvement and Fair Evidence study.

The association between statin use and the risk of Parkinson's disease remains inconclusive, particularly in Japan's super-ageing society. This study aimed to investigate the potential association between statin use and the risk of Parkinson's disease among Japanese participants aged ≥65 years. We used data from the Longevity Improvement and Fair Evidence Study, which included medical and long-term care claim data from April 2014 to December 2020 across 17 municipalities. Using a nested case-control design, we matched one case to five controls based on age, sex, municipality and cohort entry year. A conditional logistic regression model was used to estimate the odds ratios with 95% confidence intervals. Among the 56 186 participants (9397 cases and 46 789 controls), 53.6% were women. The inverse association between statin use and Parkinson's disease risk was significant after adjusting for multiple variables (odds ratio: 0.61; 95% confidence interval: 0.56-0.66). Compared with non-users, the dose analysis revealed varying odds ratios: 1.30 (1.12-1.52) for 1-30 total standard daily doses, 0.77 (0.64-0.92) for 31-90 total standard daily doses, 0.62 (0.52-0.75) for 91-180 total standard daily doses and 0.30 (0.25-0.35) for >180 total standard daily doses. Statin use among older Japanese adults was associated with a decreased risk of Parkinson's disease. Notably, lower cumulative statin doses were associated with an elevated risk of Parkinson's disease, whereas higher cumulative doses exhibited protective effects against Parkinson's disease development.