Association between serum beta-carotene levels and decline of cognitive function in high-functioning older persons with or without apolipoprotein E 4 alleles: MacArthur studies of successful aging

Background. Growing evidence from animal studies suggests an interaction between antioxidants and apolipoprotein E (APOE) alleles on cognitive functioning. We used data from a 7-year cohort study of high-functioning older persons to explore whether the associations between serum beta-carotene level and subsequent decline of cognitive function differed by APOE 4 genotype. Methods. Baseline information on sociodemographic characteristics, serum beta-carotene level, inflammation markers, APOE genotype, and cognitive functioning measured by a 9-item Short Portable Mental Status Questionnaire (SPMSQ) was obtained in 455 survivors. Multivariable logistic regression analyses were used to examine the relation between high serum beta-carotene level and risk of SPMSQ score decline in participants with or without APOE 4 alleles, while adjusting for age, sex, race, baseline SPMSQ score, and other covariates. Results. Nine (2%) study participants had homozygous and 97 (21%) had heterozygous APOE 4 alleles. Two hundred forty-nine (55%) had decline of SPMSQ scores during the follow-up. The presence of an APOE 4 allele was associated with higher risk and larger magnitude of SPMSQ score decline. The adjusted odds ratio of high beta-carotene level for cognitive decline was 0.11 (95% confidence interval, 0.02-0.57) in participants with at least one APOE 4 allele and 0.89 (95% confidence interval, 0.54-1.47) among those who were APOE 4 negative. Conclusion. Among high-functioning older persons, antioxidants and beta-carotene in particular may offer protection from cognitive decline in persons with greater genetic susceptibility as evidenced by the presence of the A-POE 4 allele.