Essential Tremor in the Elderly and Risk for Dementia.

The objective is to examine the risk of dementia in subjects with essential tremor (ET) involved in the Arizona Study of Aging and Neurodegenerative Disorders. All subjects were free of a neurodegenerative diagnosis at baseline and had annual motor, general neurological, and neuropsychological assessments. Subjects with ET were compared with controls for the risk of dementia. There were 83 subjects with ET and 424 subjects without tremor. Mean age at study entry was 80 ± 5.9 for ET and 76 ± 8.5 for controls. Median tremor duration was 5.2 years at study entry. Followup was a median of 5.4 years (range 0.9 to 12.1). The hazard ratio for the association between ET and dementia was 0.79 (95% CI 0.33 to 1.85). The hazard ratio for the association between tremor onset at age 65 or over, versus onset before age 65, was 2.1 (95% CI 0.24 to 18) and the hazard ratio for the association between tremor duration greater than 5 years, versus less than 5 years, was 0.46 (95% CI 0.08 to 2.6). We conclude that all elderly ET was not associated with an increased risk of dementia but that a subset of subjects with older age onset/shorter duration tremor may be at higher risk.