Screening for cognitive decline following single known stroke using the Mini-Mental State Examination

BACKGROUND Progressive cognitive decline develops in a nontrivial minority of stroke survivors. Although commonly used to identify cognitive decline in older stroke survivors, the usefulness of the Mini-Mental State Examination (MMSE) as a screening tool for post-stroke cognitive decline across a wider range of ages is not well established. This study therefore investigated the usefulness of the MMSE for this purpose. METHODS Twenty-seven subjects, aged 18-82 years, with a single known remote stroke were assessed using the MMSE. The frequency of cognitive impairment was determined by comparison of MMSE scores with population-based norms. Relationships between cognitive performance, motor impairments, age, gender, handedness, stroke laterality, and time since stroke also were explored. RESULTS Age-adjusted MMSE scores identified mild cognitive impairment in 22.2% and moderate-to-severe cognitive impairment in 7.4% of subjects. Raw and age-adjusted MMSE scores were inversely correlated with time since stroke, but not with other patient or stroke characteristics. CONCLUSION A relationship between time since single known stroke and MMSE performance was observed in this study. The proportion of subjects identified as cognitively impaired in this group by Z-transformation of MMSE scores using previously published normative data for this measure comports well with the rates of late post-stroke cognitive impairment reported by other investigators. These findings suggest that the MMSE, when normatively interpreted, may identify cognitive decline in the late period following single known stroke. Additionally, the lack of a relationship between MMSE and Fugl-Meyer scores suggests that the severity of post-stroke motor impairments is unlikely to serve as a clinically useful indicator of the need for cognitive assessment. A larger study of stroke survivors is needed to inform more fully on the usefulness of normatively interpreted MMSE scores as a method of screening for post-stroke cognitive decline.