Cognitive functioning as a predictor of ischemic stroke incidence

Background: Some studies have suggested that cognitive impairment is related to subsequent stroke incidence. The present study investigated the role of cognitive impairment as a predictor of ischemic stroke incidence in the Atherosclerosis Risk in Communities (ARIC) cohort. Methods: The study population consisted of 11,958 men and women 48-67 years of age in 4 U.S. communities, followed from January 1, 1990 through December 31, 1997. Cognitive performance was evaluated at the second (1990-1992) visit of the ARIC Study using 3 instruments. We identified incident strokes by means of hospital record and death certificate reviews, as well as annual telephone follow up. Results: We found no consistent associations or trends between any of the cognitive test results and ischemic stroke incidence after multiple adjustment for confounding variables. Hazard ratios for the lowest compared with the highest quartiles were 1.5 (95% confidence interval [CI] = 0.9-2.6), 1.1 (95% CI = 0.6-2.1), and 1.0 (95% CI = 0.6-1.8) for the Delayed Word Recall Test, Digit Symbol Subtest of the Wechsler Adult Intelligence Scale-Revised, and Word Fluency Test, respectively. Conclusions: The findings of the present study of relatively young subjects did not replicate the association between cognitive impairment and stroke incidence found in studies in older populations. This could be the result of the younger ages of our cohort members or the differences in cognitive tests.