A population-based study of parkinsonism in an Amish community.

BACKGROUND: Parkinson's disease (PD) is a neurodegenerative disorder with unknown cause. Genetic mutations account for a minority of cases but the role of environmental factors is unclear. METHODS: We performed a population-based screening for PD in subjects in an Amish community over age 60. PD was diagnosed using standard clinical criteria and the Unified Parkinson Disease Rating Scale motor subsection 3 (UPDRS3). Community prevalence was calculated. We constructed a community pedigree and calculated kinship coefficients, a measure of relatedness between 2 subjects, for every pair of subjects in diagnostic categories: clinically definite PD, UPDRS3 score >9, Mini-Mental State Exam (MMSE) score <25, and normal. RESULTS: Of 262 eligible subjects, 213 agreed to participate, 15 had PD, 43 had MMSE <25, 73 had UPDRS3 >9. The prevalence of PD was 5,703/100,000 with increasing prevalence in every decade of age. Excluding first-degree relatives, normal subjects were more related to each other (0.0102, SD = 0.0266) than subjects with clinically definite PD (0.0054, SD = 0.0100; p = 0.00003), subjects with UPDRS >9 (0.0076, SD = 0.0155; p = 0.00001), and subjects with MMSE <25 (0.0090, SD = 0.0180; p = 0.00003). CONCLUSIONS: PD and parkinsonian signs are common in this population and the prevalence increases with age. The finding that subjects with PD were not more related than normal subjects suggests that environmental factors may contribute to the parkinsonian phenotype in this community.

A rapid method for mass screening for parkinsonism.

Epidemiology studies of parkinsonism employ a variety of techniques for unbiased sampling of populations. No current method permits mass screening of all subjects in a population for parkinsonism by movement disorders specialists. We developed and piloted a new approach to facilitate accurate and efficient screening of large populations for diagnosis of parkinsonism and provide data on sensitivity and specificity. We evaluated 2081 welders referred for medical-legal screening. Subjects were video taped using a standardized protocol, and videos were rated on the Unified Parkinson's Disease Rating Scale motor subsection 3 (UPDRS3). A "video rater" viewed video tapes and entered ratings through a web-based database. An "in-person" examiner performed a UPDRS3 examination in a randomly selected subgroup of 48 workers drawn from the 2081. We developed quantitative diagnostic criteria for parkinsonism that established minimum diagnostic thresholds based upon UPDRS3 scores and compared these criteria with diagnosis by an in-person examiner. Specificity of these criteria compared to in-person examination was 91-100% but sensitivity was 56%. A threshold UPDRS3 score greater than nine provided 100% sensitivity and 81% specificity. Liberal criteria identified 266 (13.1%) subjects with probable parkinsonism and 220 (10.8%) subjects with definite parkinsonism. Conservative criteria identified 260 (12.8%) with probable parkinsonism and 122 (6%) with definite parkinsonism. Our screening method permits rapid assessment of parkinsonian signs. An absolute UPDRS3 score greater than nine provided the best combination of sensitivity and specificity for the diagnosis of parkinsonism, while quantitative exam-based criteria for cardinal parkinsonian signs maximized specificity. Parkinsonism as diagnosed by our criteria was common in this group of welders.