Urate and the risk of Parkinson's disease in men and women

Abstract

Introduction: High urate levels have consistently been associated with lower Parkinson's disease (PD) risk among men, but the association is less clear among women. In this study we prospectively investigated the association between high uric acid levels and PD, evaluating potential differences by sex and age.

Methods: This historical cohort study included the entire Norwegian population alive and at least 18 years old on 01/01/2004. We retrieved use of urate-lowering drugs, a marker of high urate levels/gout, from the Norwegian Prescription Database, and followed individuals from 01/01/2005 to PD onset, emigration, death, or end of follow-up on 31/12/2013. We identified 4523 incident PD cases during follow-up, and used Cox regression to estimate hazard ratios (HR_adj) and 95% confidence intervals (CI), adjusting for sex, age, and level of education. We also tested for effect modification by sex and age.

Results: Exposure to urate-lowering drugs was associated with a significantly lower PD risk (HR_adj = 0.80, 95% CI: 0.68-0.95). The association was more marked in men (HR_adj = 0.77, 95% CI: 0.63-0.94), compared to women (HR_adj = 0.89, 95% CI: 0.65-1.22), but the difference was not significant (p for effect modification = 0.61). The association varied significantly by age among women (p = 0.01) with a protective effect suggested only at higher age (above 70 years) when urate levels are higher than premenopausally (HR = 0.65, 95% CI: 0.41-1.03), but not in men (p = 0.61).

Conclusion: These findings suggest that urate may be protective against PD in both men and women.

Keywords: Cohort studies; Differences by sex; Parkinson's disease; Risk factors in epidemiology.