EPIDEMIOLOGY OF PARKINSONS-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 n ext 50 years with the aging of the population. Its prevalence varies w idely in community-based studies, possibly reflecting differences in r isk factors among the populations studied as well as differences among study methods. Heredity, race, and gender may be risk factors. Many c ase-control studies show increased risk in association with rural resi dence, farming, and herbicide or pesticide exposure, and a decreased r isk with antioxidant vitamin intake and cigarette smoking; however, th e significance of these associations in regard to disease etiology is unknown.