(7 Neurol Neurosurg Psychiatry 1997;62:10-15)

We assessed the prevalence of Parkinson's disease (PD) in a general elderly population in the Netherlands. The study formed part of the Rotterdam Study, a population-based door-to-door study, and included 6,969 persons 55 years of age or older living in a suburb of Rotterdam, the Netherlands. All participants were examined, and those who either had at least one possible cardinal sign of parkinsonism at the neurologic screening, reported that they had PD, or were taking antiparkinsonian drugs were invited for further evaluation. The prevalence of PD in this population was 1.4% (1.2% for men, 1.5% for women). Prevalence increased with age, and prevalence figures were 0.3% for those aged 55 to 64 years, 1.0% for those 65 to 74, 3.1% for those 75 to 84, and 4.3% for those 85 to 94. The corresponding age-specific figures for men were 0.4%, 1.2%, 2.7%, and 3.0%, and for women, 0.2%, 0.8%, 3.4%, and 4.8%. Among 95- to 99-year-old women the prevalence was 5.0%. Twelve percent of the subjects with PD were detected through the screening and had not been diagnosed previously.

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.

Our data suggest that a high intake of dietary vitamin E may protect against the occurrence of PD.

For Parkinson's disease (PD), little is known about how the choice of diagnostic criteria affects research results. Using data on PD from three community studies (from Argentina, the Netherlands, Italy), we compared the impact on prevalence of several sets of diagnostic criteria. Each set was based on cardinal signs--resting tremor, bradykinesia, rigidity, impaired postural reflexes--and required that other parkinsonism be excluded. Some sets had additional requirements related to duration of symptoms, asymmetry of signs, or response to medication. In terms of prevalence, much lower estimates were associated with the requirements of asymmetry of signs and response to medication. The assessment of these clinical features may not be practical in community studies. Impaired postural reflexes, as a cardinal sign, seemed superfluous. For community studies of PD, we recommend the following diagnostic criteria: at least two of resting tremor, bradykinesia, or rigidity, in the absence of other apparent causes of parkinsonism.