Differences in cognitive profile between TIA, stroke and elderly memory research subjects: a comparison of the MMSE and MoCA.

BACKGROUND: The Montreal Cognitive Assessment (MoCA) appears more sensitive to mild cognitive impairment (MCI) than the Mini-Mental State Examination (MMSE): over 50% of TIA and stroke patients with an MMSE score of ≥27 ('normal' cognitive function) at ≥6 months after index event, score <26 on the MoCA, a cutoff which has good sensitivity and specificity for MCI in this population. We hypothesized that sensitivity of the MoCA to MCI might in part be due to detection of different patterns of cognitive domain impairment. We therefore compared performance on the MMSE and MoCA in subjects without major cognitive impairment (MMSE score of ≥24) with differing clinical characteristics: a TIA and stroke cohort in which frontal/executive deficits were expected to be prevalent and a memory research cohort.
METHODS: The MMSE and MoCA were done on consecutive patients with TIA or stroke in a population-based study (Oxford Vascular Study) 6 months or more after the index event and on consecutive subjects enrolled in a memory research cohort (the Oxford Project to Investigate Memory and Ageing). Patients with moderate-to-severe cognitive impairment (MMSE score of <24), dysphasia or inability to use the dominant arm were excluded.
RESULTS: Of 207 stroke patients (mean age ± SD: 72 ± 11.5 years, 54% male), 156 TIA patients (mean age 71 ± 12.1 years, 53% male) and 107 memory research subjects (mean age 76 ± 6.6 years, 46% male), stroke patients had the lowest mean ± SD cognitive scores (MMSE score of 27.7 ± 1.84 and MoCA score of 22.9 ± 3.6), whereas TIA (MMSE score of 28.4 ± 1.7 and MoCA score of 24.9 ± 3.3) and memory subject scores (MMSE score of 28.5 ± 1.7 and MoCA score of 25.5 ± 3.0) were more similar. Rates of MoCA score of <26 in subjects with normal MMSE ( ≥27) were lowest in memory subjects, intermediate in TIA and highest after stroke (34 vs. 48 vs. 67%, p < 0.001). The cerebrovascular patients scored lower than the memory subjects on all MoCA frontal/executive subtests with differences being most marked in visuoexecutive function, verbal fluency and sustained attention (all p < 0.0001) and in stroke versus TIA (after adjustment for age and education). Stroke patients performed worse than TIA patients only on MMSE orientation in contrast to 6/10 subtests of the MoCA. Results were similar after restricting analyses to those with an MMSE score of ≥27.
CONCLUSIONS: The MoCA demonstrated more differences in cognitive profile between TIA, stroke and memory research subjects without major cognitive impairment than the MMSE. The MoCA showed between-group differences even in those with normal MMSE and would thus appear to be a useful brief tool to assess cognition in those with MCI, particularly where the ceiling effect of the MMSE is problematic.