Education and the cognitive decline associated with MRI-defined brain infarct

Objective: To assess whether educational attainment, a correlate of cognitive reserve, predicts the amount of cognitive decline associated with a new brain infarct. Methods: The Cardiovascular Health Study is a population-based, longitudinal study of people aged 65 years and older. Cognitive function was measured annually using the Modified Mini-Mental State Examination (3MS) and the Digit-Symbol Substitution Test (DSST). The authors tested whether education level modified 1) the cross-sectional association between cognitive performance and MRI-defined infarct and 2) the change in cognitive function associated with an incident infarct at a follow-up MRI. Results: In cross-sectional analysis (n = 3,660), MRI-defined infarct was associated with a greater impact on 3MS performance in the lowest education quartile when compared with others ( p for heterogeneity = 0.012). Among those with a follow-up MRI who had no infarct on initial MRI (n = 1,433), education level was not associated with the incidence, size, or location of new brain infarct. However, a new MRI- defined infarct predicted substantially greater decline in 3MS scores in the lowest education group compared with the others ( 6.3, 95% CI 4.4- to 8.2- point decline vs 1.7, 95% CI 0.7- to 2.7- point decline; p for heterogeneity < 0.001). Higher education was not associated with smaller declines in DSST performance in the setting of MRI- defined infarct. Conclusions: Education seems to modify an individual's decline on a test of general cognitive function when there is incident brain infarct. These findings are consistent with the hypothesis that cognitive reserve influences the impact of vascular injury in the brain.