Stroke and apolipoprotein E ε4 are independent risk factors for cognitive decline -: A population-based study

Background and Purpose-Stroke and apolipoprotein E epsilon 4 (ApoE epsilon 4) are individually important risk factors for cognitive decline, including Alzheimer disease. It has been suggested that ApoE epsilon 4 multiplies the risk for cognitive decline following stroke. In a population-based sample, using well-defined sensitive cognitive measures, this study investigates whether cognitive decline following stroke is worse for patients who carry the ApoE epsilon 4 allele. Methods-Subjects were participants in the Longitudinal Aging Study Amsterdam (LASA). The sample consisted of 1224 subjects, aged 62 to 85 years, who participated in the 3-year follow-up examination and for whom ApoE and stroke data were complete. We assessed cognitive decline using the Mini-Mental State Examination, the Auditory Verbal Learning Test (memory: immediate and delayed recall), and the Coding Task (information processing speed). The effects of stroke and ApoE epsilon 4 on cognitive decline were evaluated with ANOVA and multiple logistic regression analysis, adjusted for age, sex, education, and baseline cognition. Results-A synergistic effect modification for stroke and ApoE epsilon 4 on cognitive decline was not observed. Unexpectedly, instead, stroke patients canying the epsilon 4 allele demonstrated a nonsignificantly lowered risk for Mini-Mental State Examination decline (R = 0.3; 95% CI 0.1 to 1.1). ApoE epsilon 4 was associated with declines in information processing speed (OR=1,5; 95% CI 1.1 to 2.1) and small declines for immediate and delayed recall. Conclusions-Stroke and ApoE epsilon 4 may impair cognition through distinct nonsynergistic mechanisms. The slowing of information processing speed for ApoE epsilon 4 carriers was more evident than impairment in memory.