History/Epidemiology

Essential tremor was first described in 1817 by James Parkinson who differentiated between parkinsonism and what was later defined as essential tremor. In 1887, Dana compiled the first organized account of ET. Critchley reported on a large study of the condition in 1949.

Estimates concerning the prevalence of essential tremor in the general population vary greatly from 0.08 to 220 cases per 1,000 people (a 2750-fold difference). The results of population studies may be difficult to assess due to misdiagnosis (e.g., such as assigning the tremor to old age), overlooked diagnosis, or unclear diagnostic criteria. In one epidemiological review study in which centers were provided with predetermined diagnostic criteria, used the definition of ET as an action tremor, and employed community-based designs, the prevalence of ET was 4.1 to 39.2 cases per 1,000 (a 9.6-fold difference). When age was considered, the prevalence of ET in individuals over 60 years was 13.0 to 50.5 cases per 1,000. In another report, prevalence in Americans was estimated at 300 to 415 per 100,000.

ET affects males and females in equal numbers. In some patients, the symptoms begin during adolescence and then disappear for decades, only to reemerge during late adulthood.

	Causes/Genetics