Mental Status Test Scores are Inversely Correlated with Tremor Severity: A Study of 161 Elderly Essential Tremor Cases

Elan D Louis,Arthur Gillman,Amanda S Viner

doi:10.5334/tohm.86

Elan D Louis, Arthur Gillman + Show 1 more

Open Access

https://doi.org/10.5334/tohm.86

Copy DOI

Abstract

Background: There is an increasing awareness that patients with essential tremor (ET) may exhibit non-motor features, including cognitive dysfunction. Yet there are surprisingly few data in ET on the association, if any, between cognitive dysfunction and motor dysfunction (i.e., tremor severity). Establishing links between the cognitive and motor features of ET would imply that the two share a common underlying pathogenic process. Recent neuroimaging data support this notion. Methods: ET cases were enrolled in a clinical–pathological study at Columbia University Medical Center, New York. The Folstein Mini-Mental State Examination (FMMSE) and Modified Mini Mental Status Examination (mMMSE) were administered. Action tremor was rated with a total tremor score (TTS). Results: There were 161 ET cases (mean age 83.9±5.7 years, median FMMSE 28, median mMMSE 50). The FMMSE and mMMSE were inversely correlated with the TTS (r=-0.22, p=0.005; and r=-0.17, p=0.029). The association, while statistically significant, was modest in magnitude. In linear regression models that adjusted for age, gender, and education, the association between cognitive test scores and TTS remained robust (p<0.001). After excluding 68 (42.2%) cases taking ET medications with potential cognitive side effects, results remained unchanged. Conclusions: Each of the two cognitive test scores was associated with tremor severity such that greater cognitive dysfunction occurred in cases with more marked tremor. These data support recent imaging data, which suggest that the cerebellar neurodegeneration underlying ET may be involved in the expression of cognitive symptoms in ET.

Highlights

There is an increasing awareness that patients with essential tremor (ET) may exhibit non-motor features, with cognitive dysfunction being prominent among these.[1,2] Most of the emerging literature has focused on case–control differences in cognitive test scores.[2,3,4,5] By contrast, there are few data on the association, if any, between cognitive dysfunction and motor dysfunction, and the few data that do exist are conflicting.[5,6,7,8] The mechanistic basis for the cognitive dysfunction in ET is unclear, as is the basis for the tremor itself
Eleven (6.8%) participants had a Folstein Mini-Mental State Examination (FMMSE) score,24, indicating more significant cognitive impairment. Both the FMMSE and the Modified Mini Mental Status Examination (mMMSE) scores were inversely correlated with age
In this study we examined the possible links between tremor severity and performance on cognitive testing in elderly ET cases

Summary

Introduction

There is an increasing awareness that patients with essential tremor (ET) may exhibit non-motor features, with cognitive dysfunction being prominent among these.[1,2] Most of the emerging literature has focused on case–control differences in cognitive test scores.[2,3,4,5] By contrast, there are few data on the association, if any, between cognitive dysfunction and motor dysfunction (i.e., tremor severity), and the few data that do exist are conflicting.[5,6,7,8] The mechanistic basis for the cognitive dysfunction in ET is unclear, as is the basis for the tremor itself. Establishing links between the cognitive and motor features of ET would imply that the two share a common underlying pathogenic process. Recent imaging data suggest that the cerebellar neurodegeneration, which may underlie ET, may be involved in the expression of cognitive symptoms in ET.[9]

Methods

Results

Discussion