Montreal Cognitive Assessment and Mini-Mental State Examination are both valid cognitive tools in stroke

OBJECTIVE: To determine the validity of the Montreal Cognitive Assessment (MoCA) and the Mini-Mental State Examination (MMSE) as screening tools for cognitive impairment after stroke. MATERIALS AND METHODS: Cognitive assessments were administered over 2 sessions (1 week apart) at 3 months post-stroke. Scores on the MoCA and MMSE were evaluated against a diagnosis of cognitive impairment derived from a comprehensive neuropsychological battery (the criterion standard). RESULTS: Sixty patients participated in the study [mean age 72.1 years (SD = 13.9), mean education 10.5 years (SD = 3.9), median acute NIHSS score 5 (IQR 3-7)]. The MoCA yielded lower scores (median = 21, IQR = 17-24; mean = 20.0, SD = 5.4) than the MMSE (median = 26, IQR = 22-27; mean = 24.2, SD = 4.5). MMSE data were more skewed towards ceiling than MoCA data (skewness = -1.09 vs -0.73). Area under the receiver operator curve was higher for MoCA than for MMSE (0.87 vs 0.84), although this difference was not significant (χ(2) = 0.48, P = 0.49). At their optimal cut-offs, the MoCA had better sensitivity than the MMSE (0.92 vs 0.82) but poorer specificity (0.67 vs 0.76). CONCLUSIONS: The MoCA is a valid screening tool for post-stroke cognitive impairment; it is more sensitive but less specific than the MMSE. Contrary to the prevailing view, the MMSE also exhibited acceptable validity in this setting.