Cognitive trajectories in older adults with essential tremor

OBJECTIVE: Despite recent attention to the increased risk of cognitive impairment in older adults with essential tremor (ET), there are only limited data on the trajectories of cognitive change in ET or the demographic and motor predictors of such change. METHOD: This study included 148 cognitively normal individuals with ET (mean age = 76.7 ± 9.7 years) at baseline and had at least one follow-up evaluation (mean years of observation = 5.2 ± 1.6). Generalized Estimating Equations examined rates of change in six composite cognitive outcomes as a function of time, as well as demographic (age, sex, and education) and motor predictors (tremor severity, age of tremor onset, presence of rest tremor, cranial tremor, intention tremor, tandem gait) of rates of change. Demographics, medication use, and mood symptoms at baseline were covariates for all models. RESULTS: Participants evidenced a decline in global cognition, executive function, and attention (p range = <0.001-0.044) over time. Older age predicted faster decline in all cognitive outcomes except attention (p range =<0.001-0.025). Tremor severity predicted faster decline in executive function (p = 0.011). Rest tremor predicted faster decline in executive function and attention (p = 0.033, 0.017). Tandem gait missteps predicted faster decline in memory and visuospatial ability (p = 0.026, 0.028). CONCLUSIONS: Results point to a dissociation in the predictive value of different motor features for specific aspects of cognitive decline. These results shed light on the earliest manifestations of cognitive impairment in older adults with ET and implicate different pathways by which heterogeneous cognitive changes emerge.