Objective: To describe the cognitive profile of essential tremor (ET) patients and gain insight into its pathophysiological process.

Background: Nowadays, ET is considered as a cerebellar-driven disorder. Many aspects can be attributed to cerebellar dysfunction such as gait ataxia, eye movement abnormalities and cognitive impairment. It is only with the emergence of ET-plus syndrome that such clinical signs became admissible. Yet, few are the studies that depicted the type of the cognitive profile in ET.

Method: We conducted an observational cross-sectional study in a tertiary referral neurology center in Tunisia including patients diagnosed with ET or ET-plus syndrome based on the latest classification of tremors. We used a large battery of tests to assess cognitive functions including the Mini Mental status examination(MMSE) for global cognitive efficiency, the Frontal Assessment Battery(FAB) for executive function evaluation and Grober and Bushke Test for episodic memory.

Results: We included 163 patients (mean disease duration=13 years, sex ratio=0.94). More than half of our patients (56.6 %) had cognitive impairment. In fact, 26.4 % had dementia and 30.2% had mild cognitive impairment. Altered attention, executive dysfunction and episodic memory impairment were the major altered cognitive domains (52%, 50% and 49% respectively). We noted altered free delayed recall with poor reactivity to cues (mean reactivity rate=74%). We also noted the presence of intrusions (mean number of intrusions=4.3).

Conclusion: Our study findings are in line with recent publications stating that half of ET patients present with cognitive impairment. The top three altered cognitive domains pled in favor of cerebellar dysfunction. However, the presence of altered delayed recall with poor reactivity to cues and the presence of intrusions do identify with the hippocampal cognitive profile. In fact, previous postmortem studies of ET patients presenting with cognitive dysfunction pointed out increased neurofibrillary tangles and neuritic plaques. Functional MRI findings revealed topological changes within the hippocampus in ET patients. Thus, there might be more to cognitive impairment in ET than the cognitive aspect of cerebellar dysfunction. Potential Alzheimer disease-like changes are to consider as an additional substratum of cognitive impairment in ET.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/cognitive-profile-of-essential-tremor-patients-beyond-the-cerebellar-cognitive-affective-syndrome/