Apolipoprotein E ε4 allele interacts with sex and cognitive status to influence all-cause and cause-specific mortality in U.S. older adults.

Abstract

To confirm associations of apolipoprotein E (ApoE) ε4 carrier status, sex, and time-dependent cognitive status with mortality risk and to investigate these joint effects of these associations in a cohort of community-dwelling U.S. adults. Prospective cohort study. The Baltimore Longitudinal Study of Aging (BLSA). Of 3,047 BLSA participants aged 17 to 98 at first visit (60.1% male), 1,704 with complete ApoE genotype data were included, of whom 1,461 aged 50 and older with one or more visits were eligible. Time to death from all, cardiovascular, and noncardiovascular causes. Probability of survival was lower for ApoE ε4 carriers, particularly those who were older. A Cox proportional hazards model for all-cause mortality yielded a hazard ratio (HR) for ApoE ε4 carrier versus noncarriers of 1.31 (95% confidence interval (CI)=1.02-1.68). This association was also found for cardiovascular mortality. Time-dependent all-cause dementia (HR=1.73, 95% CI= 1.33-2.26) and mild cognitive impairment (HR=1.95, 95% CI=1.42-2.67) increased all-cause mortality risk, associations that were also detected for noncardiovascular mortality. When individuals were free of cognitive impairment, a dose-response relationship with ε4 alleles was found for all-cause mortality (HR=1.40, 95% CI=0.94-2.07 for 1 ε4; HR=2.61, 95% CI=1.12-6.07 for 2 ε4). After onset of Alzheimer's disease (AD), carrying only one ε4 allele resulted in an approximately 77% greater all-cause mortality risk than in noncarriers. ApoE ε4 carrier status increased all-cause mortality risk in men and interacted with time-dependent AD to increase the risk of this outcome (relative excess risk due to interaction=2.15, 95% CI=1.22-3.07). ApoE ε4 carrier status was found to increase all-cause and cardiovascular mortality risks and interacted with sex and time-dependent AD status to affect all-cause mortality.