Prediagnostic Blood Metal Levels and the Risk of Parkinson's Disease: A Large European Prospective Cohort.

BACKGROUND:Metals have been postulated as environmental concerns in the etiology of Parkinson's disease (PD), but metal levels are typically measured after diagnosis, which might be subject to reverse causality. OBJECTIVE:The aim of this study was to investigate the association between prediagnostic blood metal levels and PD risk. METHODS:A case-control study was nested in a prospective European cohort, using erythrocyte samples collected before PD diagnosis. RESULTS:Most assessed metals were not associated with PD risk. Cadmium has a suggestive negative association with PD (odds ratio [95% confidence interval] for the highest quartile, 0.70 [0.42-1.17]), which diminished among never smokers. Among current smokers only, lead was associated with decreased PD risk (0.06 [0.01-0.35]), whereas arsenic showed associations toward an increased PD risk (1.85 [0.45-7.93]). CONCLUSIONS:We observe no strong evidence to support a role of metals in the development of PD. In particular, smoking may confound the association with tobacco-derived metals. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.