Epidemiology of Parkinson's disease

Parkinson's disease (PD) currently affects at least 500,000 people in the United States alone. Its prevalence is expected to triple in the next 50 years with the aging of the population. Its prevalence varies widely in community-based studies, possibly reflecting differences in risk factors among the populations studied as well as differences among study methods. Heredity, race, and gender may be risk factors. Many case-control studies show increased risk in association with rural residence, farming, and herbicide or pesticide exposure, and a decreased risk with antioxidant vitamin intake and cigarette smoking; however, the significance of these associations in regard to disease etiology is unknown.