APOE and Alzheimer disease: While midlife cognitive activity did not have any moderation effect for the association between APOE4, Aβ retention, and AD-CM, midlife physical activity significantly moderated the effect of Aβ retention on AD-CM (Table 4 and Figure 2B), suggesting the effect of global Aβ retention, which is closely related to APOE4, on AD-CM can be changed by midlife physical activity level.