Intellectual decline after stroke: the Framingham Study

BACKGROUND AND PURPOSE: The causes and characteristics of cognitive decline after stroke are poorly defined, because most studies have relied on the diagnosis of dementia after stroke, without measurement of prestroke cognitive function. METHODS: The Mini-Mental State Examination (MMSE) was used to assess the cognitive performance of 74 subjects from the Framingham Study cohort who had suffered a stroke during a 13-year period. We compared their poststroke cognitive performance with the prestroke MMSE scores collected during their biennial examinations, and their prestroke/poststroke changes in MMSE score were then compared with those of 74 control subjects matched for age and sex. Cases and controls underwent testing for symptoms of depression using the Center for Epidemiologic Studies of Depression (CES-D) scale, and these findings were correlated with their cognitive performance. Changes in cognitive performance in the cases were correlated with the CT-documented characteristics of the stroke. RESULTS: The cases had a significantly lower mean+/-SE MMSE score at prestroke baseline (27.28+/-0.34) than did the control subjects (28.08+/-0.21), a difference that became more pronounced (23.57+/-0.92 versus 28.31+/-0.25; P<.001) after stroke. The poststroke decline in cognitive function in the cases was correlated only with a large, left-sided stroke on CT. The CES-D scores were significantly higher in the cases, but nondepressed cases had significantly lower MMSE scores than nondepressed controls. CONCLUSIONS: Stroke is followed by a significant decline in cognitive performance when prestroke and poststroke measurements are compared. Although depression is more frequent in the stroke patients, their intellectual decline appears to be independent from the presence of depression.