Incidence, Risk and Prognosis of Parkinson Disease

Background Parkinson disease is the second most common neurodegenerative disease and the proportion of people suffering from parkinsonism and Parkinson disease is expected to increase as populations age. Few studies investigated the incidence of parkinsonism and Parkinson disease in the general population, and most of these were based on clinical data only. Objective To estimate the incidence of parkinsonism and Parkinson disease in a general population. Methods In the Rotterdam study, a prospective population-based cohort study in people aged 55 years and older, we assessed ageand sex-specific incidence rates of parkinsonism and Parkinson disease among 6,839 participants who were free of parkinsonism at baseline. Case-finding involved in-person screening at both baseline and two followup 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 Parkinson disease. The incidence of both parkinsonism and Parkinson disease increased with age, with incidence rates for Parkinson disease rising from 0.3 per 1000 person years in subjects aged 55-65 years, to 4.4 per 1000 person years for those aged 85 years and older. The overall ageadjusted incidence rate of any parkinsonism was not different in men and women, but men seem to have a higher risk for Parkinson disease (male-to-female ratio 1.54; 95% CI 0.95 – 2.51). Conclusion Incidence rates for both parkinsonism and Parkinson disease were higher than those reported by most previous studies. This may be due to our intensive case-finding methods involving in-person screening.