Changes in Cognitive Function over 3 Years after First-Ever Stroke and Predictors of Cognitive Impairment and Long-Term Cognitive Stability: The Erlangen Stroke Project

BACKGROUND AND PURPOSE: Cognitive impairment (CI) is frequent after stroke, but data from population-based stroke cohorts on the natural course of CI are limited. The purpose of this study was to determine changes in cognitive status over 3 years after stroke. METHODS: Data were collected from the Erlangen Stroke Project, an ongoing population-based stroke registry. The Mini-Mental State Examination (MMSE) for assessing global cognitive function was used; CI was defined as an MMSE score <24. RESULTS: From February 1998 to January 2006, 630 patients with first-ever stroke were included. Prevalence rates of CI at 3 months, 1 and 3 years were 15, 13, and 12%. In multivariable analysis, stroke severity, i.e. Barthel index (p < 0.001), age (OR = 1.03; 95% CI = 1.00-1.05) and diabetes mellitus (OR = 2.03; 95% CI = 1.13-3.67) were associated with CI at 3 months. Recovery rate from CI at 3 months after stroke was found to be 31% over the following 3 years. Intact cognitive function rate was 71% over 3 years and inversely associated with age (OR = 0.96; 95% CI = 0.96-0.94) and stroke severity (p < 0.001). CONCLUSION: CI is frequent among stroke survivors and associated with age, stroke severity, and diabetes mellitus, but recovery occurs in approximately one third of the patients over the course of 3 years. Factors affecting intact cognitive function over time are increasing age and stroke severity.