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.
Racette
Brad A
BA
Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA. racetteb@neuro.wustl.edu
Good
Laura M
LM
Kissel
Abigail M
AM
Criswell
Susan R
SR
Perlmutter
Joel S
JS
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015146:Midwestern United States / Q000453:epidemiology; D020734:Parkinsonian Disorders / Q000453:epidemiology / Q000208:ethnology* / Q000235:genetics; D044382:Population Groups / Q000208:ethnology* / Q000235:genetics; D015995:Prevalence; D012067:Religion; D012111:Residence Characteristics