Risk of incident dementia in essential tremor: a population-based study.
Essential tremor (ET) is a late-life neurological disease. Mild cognitive deficits as well as an association with prevalent dementia have been reported in recent case-control studies. We determined whether ET was associated with an increased risk of incident dementia. In a population-based study of older people in central Spain (NEDICES), nondemented ET cases and controls were followed prospectively. Incident dementia at follow-up was diagnosed using DSM-IV criteria and the risk of incident dementia was estimated in ET cases versus controls using Cox proportional hazards models. 3,891 participants had a mean duration of follow-up of 3.2 years. Sixteen (7.8%) of 206 ET cases developed incident dementia versus 145 (3.9%) of 3,685 controls (unadjusted relative risk [RR]=2.08, 95% CI=1.24-3.50, P=0.006 and adjusted RR=1.66, 95% CI=0.99-2.80, P=0.054). In an adjusted model, ET cases with tremor onset after age 65 years were twice as likely to develop incident dementia than were controls (RR=1.98, 95% CI=1.14-3.45, P=0.01), whereas ET cases with tremor onset<age 65 years and controls were equally to develop incident dementia (RR=0.74, 95% CI=0.19-3.20, P=0.79). Although ET is often considered a benign condition, in this prospective, population-based study, elderly-onset ET was associated with an increased risk of incident dementia. The basis for this dementia, which is not known, requires additional study.
Bermejo-Pareja
Félix
F
Department of Neurology, University Hospital 12 de Octubre, Madrid, Spain.
Louis
Elan D
ED
Benito-León
Julián
J
D000368:Aged; D000369:Aged, 80 and over; D018672:Community Health Planning; D003704:Dementia / Q000453:epidemiology* / Q000209:etiology*; D020329:Essential Tremor / Q000150:complications* / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales; D012306:Risk; D013030:Spain / Q000453:epidemiology