Objective: To identify if the Montreal Cognitive Assessment (MoCA) is a sensible tool to differentiate cognitive impairment profiles between patients with Essential Tremor (ET) and Parkinson’s disease (PD).

Background: Cognitive decline has been widely recognized in patients with Parkinson’s disease and is subject of recent interest in Essential Tremor.  The very distinct pathophysiology of both conditions imply different mechanisms of cognitive impairment and this is frequently recognized in the clinical practice. Essential Tremor, long thought to be a mono-symptomatic disease, is now recognized as a heterogeneous condition that affects multiple cerebral functions such as mood and cognition which remain highly underdiagnosed.  Domains particularly affected in ET are those that rely on the integrity of the prefrontal cortex, which suggests involvement of frontocerebellar circuits in this disease. On the other hand PD patients are described as impaired in the attention/executive functions, memory, and visuospatial skills.

Method: 124 patients, 44 with ET and 80 with PD (mean age 62.8±13 65% female) were recruited form our previous cohort. MoCA Spanish version (MoCA SP) was used to screen for cognitive impairment (mean score 22.1 +/- 4.6). Years of education were taken into account to adjust for the recognition of cognitive impairment (mean 10.6 years ±5.2.) Cognition subdomains were categorized as follows: visuospatial/executive, attention, language, abstraction, delayed recall and orientation. Each domain was analyzed individually and then compared between groups.

Results: As expected, there was a high proportion of patients with any degree of cognitive impairment (MoCA-SP ≤25): 75% of the PD patients and 81.1% of the ET patients had a positive screening test for cognitive decline (p= .385). Both groups had subpar scores in the visuospatial/executive (p= .267), attention (p= .702) and delayed recall (p= .593) subdomains, without statistically significant differences among them. The abstraction subdomain, though impaired in both groups, was more affected in ET patients (p. <.0001).

Conclusion: Though we confirmed a high prevalence of cognitive decline in patients with PD and ET, no significant differences were relevant in this initial screening study. The limitations of MoCA-SP mandate further, more profound neuropsychological testing to better categorize the cognitive profiles of both groups.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/cognitive-impairment-profile-of-patients-with-essential-tremor-and-parkinsons-disease/