Apolipoprotein E ε4 Allele Is Associated with Reduced Retention of the "Where" Memory Component in Cognitively Intact Older Adults

Objective: The present study investigated the effect of the apolipoprotein E (ApoE) epsilon 4 allele on the four memory components (i.e., who, when, where, and what) among cognitively intact older adults. Methods: Participants comprised 47 cognitively intact older adults, who were classified into 2 groups based on the presence or absence of at least 1 ApoE epsilon 4 allele. All participants completed standardized neuropsychological tests, including the Logical Memory subtest of the Wechsler Memory Scale-III with a revised scoring method. Results: The results revealed that recollection for each component followed a pattern of who > what > when = where. Furthermore, a significant group-by-component-by-condition interaction indicated that the presence of the ApoE epsilon 4 allele resulted in a disproportionately detrimental effect on the where component retention in the verbal episodic memory task; this finding was significantly correlated with hippocampal volumes. Conclusion: These results highlighted the importance of evaluating the subcomponents of verbal episodic memory to detect subtle cognitive differences related to ApoE epsilon 4 status, which could help elucidate the mechanism behind the cascades caused by ApoE epsilon 4 in the trajectories of cognitive aging.