Association of Essential Tremor With Dementia and Affective Disorders: A Meta-Analysis

Abstract

BackgroundThe dementia and affective disorders are common non-motor features in patients with essential tremor (ET). However, the relationship of ET with cognitive impairments and affective disorders remains controversial. This meta-analysis aimed to analyze the association of ET with dementia and affective disorders.MethodsOriginal studies published from January 1999 to October 2019 were systematically searched from the database of Medline (OvidSP), EMBASE (OvidSP), and the Cochrane Central Register of Controlled Trials. Pooled standard mean difference (SMD, random effect model), odds ratios (ORs), relative risk (RR), and 95% CI were calculated.ResultsCompared with the Non-ET group, patients with ET had significantly lower Mini-Mental State Examination (MMSE) score (SMD, −1.16; 95% CI, −1.75 to −0.58; p = 0.0001) and had significantly higher depressive and anxiety symptoms scale score (SMD, 0.55; 95% CI, 0.22–0.87; p = 0.0009). The OR for dementia and affective disorders in individuals with ET compared with individuals without ET was 2.49 (95% CI, 2.17–2.85, p < 0.00001). While there was no significant difference in Montreal Cognitive Assessment (MoCA) score between ET and Non-ET groups (SMD, −0.52; 95% CI, −0.16 to 0.13; p = 0.23), there was a significant difference in the risk of mortality between ET and Non-ET groups (RR = 4.69, 95% CI, 2.18–10.07).ConclusionThe non-motor symptoms should not be neglected among patients with ET. However, the causal relationship between ET and dementia, depression, and anxiety is unclear.

Cognitive impairment in essential tremor assessed by the cerebellar cognitive affective syndrome scale

“…The clinical cognitive assessment was performed with the version 1A of the CCAS-S: a mean raw score was calculated for each of the 10 items which composed the scale (semantic fluency task, phonemic fluency task, verbal category switching task, forward and backward digit span, cube drawing task, verbal registration task, verbal similarities task, Go No-Go task, and affect evaluation) (12). A raw score is obtained for each task, with a minimum passing score.…”

“…Historically considered as benign monosymptomatic affection, the understanding of ET impact has considerably evolved along with amounting pathological and functional imaging evidence. Indeed, the cortico-cerebellar loops affected in ET, in addition to motor control, are involved in many perceptual and cognitive processes (9,10) which may explain why non-motor symptoms are increasingly identified in ET including mood disorders and cognitive impairment (11,12). In view of these pathological (4) and neuroimaging (5, 7-9) abnormalities in ET patients involving the cortico-cerebellar loops, the cognitive disorders observed in these patients could be related to a disruption of this corticocerebellar tract.…”