Validity of the Montreal Cognitive Assessment in the Detection of Cognitive Dysfunction in Huntington's Disease

Abstract

The purpose of this study was to assess the convergent and discriminative validity of the Montreal Cognitive Assessment (MoCA) as a screening tool for cognitive dysfunction in Huntington's disease (HD). Twenty HD patients with cognitive deficit and 23 normal controls (NC) without cognitive deficit were matched for age, sex, and education. The mean MoCA score was 20.5 (SD = 5.5) in HD and 27.5 (SD = 2.2) in NC. The MoCA correlated in both samples with the brief cognitive battery composite score (r = .81, p < .001). With the screening and diagnostic cutoff scores determined at <26 points, the MoCA showed a sensitivity of 94% and a specificity of 84% in the detection of cognitive dysfunction in HD. The area under the receiver-operating characteristics curve (95% confidence interval) for the MoCA was 0.90 (0.809–0.997), p < .001. Our results show that the MoCA is a suitable tool for assessing cognitive dysfunction in patients with HD.

Key words:

• dementia
• Huntington's disease
• Montreal Cognitive Assessment

ACKNOWLEDGEMENTS

The work was supported by grants from the Czech Ministry of Education: Research Program (grant number MSM0021620849).

The authors are grateful to Aaron Rulseh, M.D., for language revision and to the reviewers for their insightful comments.

Notes

Note. The possible range of the TFC is 1–13, and that of the UHDRS total motor scores is 0–124.

Y = years; MoCA = Montreal Cognitive Assessment; MADRS = Montgomery-Asberg Depression Rating Scale; HARS = Hamilton Anxiety Rating Scale; UHDRS = Unified Huntington's Disease Rating Scale; UHDRS-FIS = Functional Independence Scale (possible range = 0–100); TFC = Total Functional Capacity.

*Mann-Whitney U Test.

†Significant after Bonferroni correction for multiple comparisons.

FCSRTf = Free and Cued Selective Reminding Test, Free Recall; FCSRTc = Free and Cued Recall Test, Cued Recall; FCSRTt = Free and Cued Recall Test, Total Score; RCFT-C = Rey Complex Figure Test Copy trial; RCFT-I = Rey Complex Figure Test Immediate Recall trial (3-minute delay); Stroop-C = Stroop Test, Color Naming; Stroop R = Stroop Test, Word Reading; Stroop I = Stroop Test, Interference; COWAT = Controlled Oral Word Association Test, Letter Fluency (N, K, P); SDMT = Symbol–Digit Modalities Test; GNS = Global Neuropsychology Score based on brief cognitive battery (averaged sum of z-scores from the brief cognitive battery: FCSRT, RCFT, Stroop, COWAT, SDMT).

† p < .001.

‡ p < .05.

Note. n = 43; AUC (95% CI) = .903 (0.809–0.997); p < .001. PPV = positive predictive value; NPV = negative predictive value; AUC = area under curve; CI = confidence interval.

*Point of maximal combined sensitivity and specificity.

†Optimal screening cutoff point.

‡Optimal diagnostic cutoff point.

MoCA total = sum of all MoCA subtests, range 0–30; RCFT-C = Rey Complex Figure Test Copy trial; RCFT-I = RCFT Immediate Recall trial (3-minute delay); SDMT = Symbol–Digit Modalities Test; Stroop-C = Stroop Test, Color Naming; Stroop-R = Stroop Test, Word Reading; Stroop-I = Stroop Test, Interference; COWAT = Controlled Oral Word Association Test, Letter Fluency (N, K, P); FCSRT = Free and Cued Selective Reminding Test, Total Score; UHDRS = Unified Huntington's Disease Rating Scale; UHDRS-FAS = Functional Assessment Scale (a rating based on 25 questions [yes/no] that query the ability to perform daily activities independently); UHDRS-FIS = Functional Independence Scale (an assigned rating from 0 to 100 points based on 25 questions [yes/no] that query the ability to perform daily activities independently); FIS rating = subjects were classified as functionally impaired if they obtained an FIS rating of 80 or lower; TFC = UHDRS Total Functional Capacity (range = 0–13, based on five questions concerning occupation, finances, household chores, activities of daily living, and care level.

†p < .05.