title: Ethnic differences in essential tremor.
abstract: BACKGROUND
  Ethnic differences in the clinical characteristics (severity and distribution) of essential tumor (ET) have not been studied. The presence of these differences suggests that ET is not a homogeneous disease and that there is variability in disease expression under different circumstances. As part of a community-based study, we evaluated a multiethnic group of cases.
  
  
  OBJECTIVE
  To assess whether there are ethnic differences in the clinical characteristics of ET.
  
  
  METHODS
  Elderly residents of Washington Heights-Inwood, New York, were enrolled in a community-based health study (N = 2117). Participants underwent a medical interview and a neurological examination conducted by a neurologist, and subjects with ET were identified. These subjects with ET were then enrolled in a community-based study of ET and underwent a tremor interview, a videotaped tremor examination, and in some cases, a performance-based test of function and quantitative computerized tremor analysis. A total tremor score (range, 0-36, with 0 indicating no tremor and 36 indicating maximum tremor) was assigned to each subject based on 2 neurologists' ratings of the tremor examination.
  
  
  RESULTS
  Among 62 subjects with ET (white [n = 16], African American [n = 18], and Hispanic [n = 28]), there were ethnic differences in the total tremor score (F = 3.68, P = .03). In a multiple regression model adjusting for age, white subjects had a mean total tremor score that was 5.3 points lower than that of nonwhite subjects (P = .008). We divided the nonwhite group into African American and Hispanic subgroups. In a regression model adjusting for age and duration, the white group had a mean total tremor score that was 6.1 points lower than that of the Hispanic group (P = .07) and 7.2 points lower than that of the African American group (P = .05). The mean performance-based test score was 1.7 times higher in the African American group and 2.1 times higher in the Hispanic group compared with the white group (P = .38). No subjects in the African American group had head tremor, while 4 subjects in the white group (25%) and 8 subjects in the Hispanic group (29%) did have head tremor (chi2 = 6.17, P = .05).
  
  
  CONCLUSIONS
  There are ethnic differences in the expression of ET, suggesting that ET is not a homogeneous disorder. These differences may reflect phenotypic variability caused by genotypic differences or differences in exposure to environmental factors that influence tremor.
authors.affiliation: Gertrude H. Sergievsky Center, Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA. Louisel@sergievsky.cpmc.columbia.edu
authors.forename: E D
authors.initials: ED
authors.lastname: Louis
authors.forename: L F
authors.initials: LF
authors.lastname: Barnes
authors.forename: B
authors.initials: B
authors.lastname: Ford
authors.forename: S L
authors.initials: SL
authors.lastname: Pullman
authors.forename: Q
authors.initials: Q
authors.lastname: Yu
mesh_terms: D001741:Black or African American; D000368:Aged; D000369:Aged, 80 and over; D020329:Essential Tremor / Q000175:diagnosis / Q000208:ethnology*; D005260:Female; D006630:Hispanic or Latino; D006801:Humans; D008297:Male; D012044:Regression Analysis; D012720:Severity of Illness Index; D044465:White People