Predictors of Incident Dementia in a Cohort of Elders with Essential Tremor: A Prospective, Longitudinal Study.

Abstract

Introduction: Elders with essential tremor (ET) are at a heightened risk for incident dementia. Although the consequences of this diagnosis are formidable, we know little about what factors elevate the risk of ET-dementia. We analyzed data from a large, prospective, longitudinal study of cognitive status in an ET cohort to examine whether a range of demographic, lifestyle, and clinical variables contribute to dementia risk.

Methods: The cognitive status (normal cognition [NC], mild cognitive impairment [MCI], or dementia) of a baseline sample of 350 ET cases (M age = 79.5 years) was tracked for up to 7.5 years (M follow-up = 4.7 years). Cox proportional hazards regressions identified baseline characteristics that predicted the development of dementia.

Results: Older age and greater cognitive impairment at baseline (MCI versus NC) each predicted incident dementia, HR > 1.10, p < 0.0001. Diminished functional abilities (HR = 0.39), greater gait impairment (HR = 1.30), lower confidence in one's balance skills (HR = 0.98), and more depressive symptoms at baseline (HR = 1.08) further predicted conversion to dementia, all p < 0.006. Neither continuous nor categorical measures of ET onset age predicted incident ET-dementia.

Conclusions: These data represent the most comprehensive assessment to date of risk factors for ET-dementia in terms of number of factors studied and cohort size. At least one of these risk factors - depression - is modifiable and may offer intervention points to reduce risk of dementia. Older age of ET onset, previously viewed as a risk factor, did not predict incident ET-dementia.