Prevalence of essential tremor in the territory of Lake Trasimeno, Italy: results of a population-based study.

Because of the great variability in previous epidemiological data, and in light of the more accurate definition and diagnostic criteria recently formulated, we designed the present study to evaluate the prevalence of essential tremor (ET) in an Italian population. The study population included 13,604 individuals, who represented all patients of 11 family doctors working in the Territory of Lake Trasimeno in central Italy. Assessment of the sample and selection of the suspected cases were carried out by the same family doctors, previously trained to apply the inclusion and exclusion criteria for the definition of ET based on the Classification Criteria of the Movement Disorder Society (1998) and the Guidelines of the Ad Hoc Committee (2000). The total population was assessed over a period of 12 months. The age-adjusted prevalence of ET was 1.21% (95% confidence interval, 0.83-1.76). The probability of presenting with ET tended to increase with age and males showed a 50% greater risk for developing ET (male/female ratio = 1.5 for each age class). Our results are in line with the most recent epidemiological findings, which suggest a lower prevalence of ET than in older studies. These results can be attributed to the application of more stringent diagnostic criteria. (c) 2006 Movement Disorder Society.