Update in the epidemiology of Parkinson's disease

PURPOSE OF REVIEW: In the past 18 months, several important studies on the epidemiology of Parkinson's disease have been published. In particular, large cohorts have identified sufficient incident patients with Parkinson's disease to study risk or protective factors of Parkinson's disease; one of the important recent events in the field is the publication of some of their findings. RECENT FINDINGS: We will first review findings of descriptive studies on the frequency of the disease and its geographic or temporal distribution. We will then summarize the findings of analytical studies dealing with risk or protective factors in the fields of dietary and lifestyle factors (cigarette smoking, coffee and tea drinking, uric acid, dairy products), environmental exposures (pesticides, lead, manganese, welding), hormonal factors (oophorectomy), vascular risk factors (diabetes, hypertension, cholesterol level), pharmacoepidemiology (NSAIDs, statins), and familial aggregation. SUMMARY: Epidemiologic studies have consistently found that some exposures are inversely (e.g., cigarette smoking) or positively associated with Parkinson's disease (e.g., pesticides), while their findings are, at the present time, less consistent for other exposures (e.g., NSAIDs, vascular risk factors). Finally, recent studies have investigated new research fields (e.g., hormonal factors, uric acid, pharmacoepidemiology) and additional data need to be collected.