Impact of apolipoprotein E genotypes on vitamin E and memantine treatment outcomes in Alzheimer's disease

INTRODUCTION: Because apolipoprotein E (APOE) genotypes are known risk factors for Alzheimer's disease (AD), they have been measured in clinical trial participants to determine their effect on treatment outcome. METHODS: We determined APOE genotypes in a subset of subjects (N = 415) who participated in a randomized controlled trial of vitamin E and memantine in 613 veterans with mild-to-moderate AD. RESULTS: Similar to the primary study, substudy participants receiving vitamin E also had slower functional decline than those receiving placebo. Overall, there was no difference in the rate of functional decline between APOE ε4 allele carriers and noncarriers. A significant interaction was observed between treatment and the APOE genotype on AD progression: ε4 carriers declined faster than noncarriers in the vitamin E plus memantine treatment arm. DISCUSSION: APOE genotypes may modulate AD treatment response and should be included in the design of future randomized controlled trials.