Prevalence of Parkinson's disease in the biracial population of Copiah County, Mississippi.

A door-to-door survey of major neurologic disorders was conducted in the essentially biracial population of Copiah County, MS, using a pretested screening questionnaire. All those suspected of having Parkinson's disease were requested to have a neurologic examination by board-certified neurologists. The study also included those living in institutions. The prevalence of Parkinson's disease (age 40+) was 347 per 100,000 inhabitants. No substantial differences in the age-adjusted prevalence ratios by race or by sex were found in the population studied. Age-specific prevalence ratios for Parkinson's disease increase with advancing age. Over 40% of identified cases were newly diagnosed during the study.