Prevalence of essential tremor in a multiethnic, community-based study in northern Manhattan, New York, N.Y.

BACKGROUND Our aims were to: (1) estimate the prevalence of essential tremor (ET) in a community-based study in northern Manhattan, New York, N.Y., USA; (2) compare prevalence across ethnic groups, and (3) provide prevalence estimates for the oldest old. METHODS This study did not rely on a screening questionnaire. Rather, as part of an in-person neurological evaluation, each participant produced several handwriting samples, from which ET diagnoses were assigned. RESULTS There were 1,965 participants (76.7 +/- 6.9 years, range = 66-102 years); 108 had ET [5.5%, 95% confidence interval (CI) = 4.5-6.5%]. Odds of ET were robustly associated with Hispanic ethnicity versus white ethnicity [odds ratio (OR) = 2.19, 95% CI = 1.03-4.64, p = 0.04] and age (OR = 1.14, 95% CI = 1.03-1.26, p = 0.01), i.e. with every 1 year advance in age, the odds of ET increased by 14%. Prevalence reached 21.7% among the oldest old (age > or = 95 years). CONCLUSIONS This study reports a significant ethnic difference in the prevalence of ET. The prevalence of ET was high overall (5.5%) and rose markedly with age so that in the oldest old, more than 1 in 5 individuals had this disease.