Associations Between Cognitive Profiles and Balance in Essential Tremor

TL;DR

This study finds that people with essential tremor who have certain cognitive issues, like memory or processing speed problems, also have worse balance and gait, independent of medication use.

Contribution

The study identifies distinct cognitive subtypes in essential tremor and links them to specific balance and gait impairments.

Findings

Low memory and low executive function groups had worse balance test scores compared to cognitively normal individuals.

Low executive function was associated with worse Timed Up and Go scores.

Medication use did not affect gait and balance test results but predicted reported falls in daily life.

Abstract

Essential Tremor (ET) is increasingly recognized as phenotypically heterogeneous disorder, which may encompass alterations in gait, balance and cognitive dysfunction. Disruption in cerebellar-thalamic-cortical circuits results in varying patterns of executive and memory dysfunction and balance disorders. The current study proposed two aims: 1) identify cognitive subtypes within individuals with essential tremor, and 2) examine for a correlation between these subtypes and gait and balance dysfunction. We hypothesize that gait and balance dysfunction are more common in individuals with ET who demonstrate greater cognitive difficulties.

Seventy-one individuals underwent neuropsychological and physical therapy examinations as part of presurgical deep brain stimulation (DBS) evaluations that included measures of gait and balance (Mini-BESTest; Timed Up and Go, SARA). People with ET were categorized into Cognitively Normal (N = 29), Low Executive Function/Processing Speed (N = 17), and Low Memory Multi-domain groups (N = 25).

Regression analyses show that scores on the Mini-Balance Evaluation Systems Test and Scale for the Assessment and Rating of Ataxia were worse in the Low Memory and Low Executive Function groups compared to the cognitively normal group; age was also a significant predictor. Scores on the Timed Up and Go were worse for the Low Executive Function compared to the cognitive normal group; age and education were also significant predictors. Medication use was not associated with any of the clinical gait and balance tests. However, medication use and age were significant predictors of reported falls in daily life.

A subset of individuals with ET experience cognitive dysfunction that coalesce into processing speed deficits or immediate memory deficits. These cognitive subtypes were associated with greater difficulty in balance and gait as compared to cognitively normal ET patient and this difference could not be accounted for by medications.

Figures