Environmental Exposures and Risks for Parkinson's Disease

Parkinson disease (PD) is a degenerative movement disorder that affects up to 2% of persons older than age 60. The etiology of PD remains poorly understood, despite extensive research during the past 50. years. Some genetic factors are consistently associated with PD risk, as is tobacco smoking, which appears protective. Additional lifestyle factors, comorbid conditions, and environmental exposures are likely to play important etiologic roles. Environmental epidemiologic research has been guided by mechanistic considerations, toxicological evidence, and clinical case reports among persons with characteristically high-dose exposures. Agents that have received the most attention are pesticides, metals, and solvents. To date, no agent that can account for a sizable fraction of PD incidence has been identified. Future research should prioritize longitudinal studies of selected occupational or environmental high-dose groups to characterize dose-response relationships for disease risk and progression.