Essential tremor is associated with dementia: prospective population-based study in New York.

BACKGROUND: Mild cognitive deficits, mainly in frontal-executive function and memory, have been reported in patients with essential tremor (ET). Furthermore, an association between ET and dementia has been reported in a single population-based study in Spain. This has not been confirmed elsewhere.

OBJECTIVE: To determine whether baseline ET is associated with prevalent and incident dementia in an ethnically diverse, community-based sample of elders.

METHODS: Community-dwelling elders in northern Manhattan were enrolled in a prospective cohort study. Baseline ET diagnoses were assigned from handwriting samples. Dementia was diagnosed at baseline and follow-up using DSM-III-R criteria.

RESULTS: In cross-sectional analyses, 31/124 (25.0%) ET cases had prevalent dementia vs 198/2,161 (9.2%) controls (odds ratio [OR](unadjusted) = 3.31, 95% confidence interval [CI] = 2.15-5.09, p < 0.001; OR(adjusted) = 1.84, 95% CI = 1.13-2.98, p = 0.01). In prospective analyses, 17/93 (18.3%) ET cases vs 171/1,963 (8.7%) controls developed incident dementia (hazard ratio [HR](unadjusted) = 2.78, 95% CI = 1.69-4.57, p < 0.001; HR(adjusted) = 1.64, 95% CI = 0.99-2.72, p = 0.055).

CONCLUSIONS: In a second population-based study of elders, essential tremor (ET) was associated with both increased odds of prevalent dementia and increased risk of incident dementia. Presence of dementia, therefore, appeared to be greater than that expected for age (i.e., a disease-associated feature). Rather than attributing cognitive complaints in patients with ET to old age, assessment and possible treatment of dementia should be routinely incorporated into the treatment plan.