Objective: Neuropsychological assessments are useful tools for examining and tracking cognitive impairment in individuals with neurological disorders; however, a full neuropsychological battery is not realistic for most routine medical visits.  Since clinicians are expected to assess cognitive function in a concise—yet, comprehensive—manner, brief measures of global cognitive function are routinely used in clinical settings. It is therefore critical to assess their utility in specific neurological populations. The present study compares the longitudinal utility of two brief cognitive instruments in HD.

Background: Currently, the most frequently used screening instrument is the Mini Mental State Examination (MMSE). A major limitation of the MMSE is the shortage of items assessing executive function and attention. These limitations are of increased concern when assessing clinical populations characterized by frontostriatal dysfunction. The Montreal Cognitive Assessment (MoCA), a more recently developed brief measure of cognitive function, encompasses a broader range of cognitive-specific items compared to the MMSE and has been shown to have high specificity and sensitivity when characterizing HD; however, there is a lack of studies examining its efficacy in detecting cognitive alterations over time.

Method: Individuals with a definitive diagnosis of HD and three or more testing occasions for both the MoCA and MMSE were included in analyses. The MMSE was administered to 136 and the MoCA to 125 subjects. Multilevel modeling was used to examine the average rate of decline on both measures across time.

Results: HD patients had an average total MoCA score of 20.65 at baseline and average total MMSE score of 24.93 at baseline. Mean rates of decline on the MoCA and MMSE were .36 (p < .01) and .68 (p < .01) points per visit, respectively. Education level did not predict rate of decline but did predict performance at baseline.

Conclusion: As expected, both MMSE and MoCA scores decline significantly over time; however, a lower baseline score and moderately declining slope on the MoCA may be more characteristic of HD pathology. The tendency for ceiling and floor effects on the MMSE could possibly explain a higher average score at enrollment and steeper slope across time. The MoCA may be a more useful measure for assessing cognitive changes in HD because of its sensitivity to executive dysfunction.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/longitudinal-utility-of-the-montreal-cognitive-assessment-and-mini-mental-state-exam-in-huntingtons-disease-hd/