Incidence of parkinsonism and Parkinson disease in a general population

OBJECTIVE: To investigate the incidence of parkinsonism and Parkinson disease (PD) in the general population using in-person screening along with clinical data. METHODS: In the Rotterdam study, a prospective population-based cohort study of people aged > or =55 years, the authors assessed age- and sex-specific incidence rates of parkinsonism and PD among 6,839 participants who were free of parkinsonism at baseline. Case finding involved in-person screening at baseline and two follow-up visits, and additional information was obtained through continuous monitoring of the cohort by computer linkage to general practitioners' and pharmacy records. RESULTS: After a mean follow-up period of 5.8 years, 132 subjects with incident parkinsonism were identified, of whom 67 (51%) had PD. The incidence of parkinsonism and PD increased with age, with incidence rates for PD increasing from 0.3 per 1000 person-years in subjects aged 55 to 65 years, to 4.4 per 1000 person-years for those aged > or =85 years. The overall age-adjusted incidence rate of any parkinsonism was not different in men and women, but men seem to have a higher risk for PD (male-to-female ratio, 1.54; 95% CI, 0.95 to 2.51). CONCLUSION: Incidence rates for parkinsonism and Parkinson disease were higher than those reported by most previous studies, possibly because of the authors' intensive case-finding methods involving in-person screening.