Our findings diverge from those of Walhovd et al., who studied 1181 cognitively healthy participants from age 4 to 95 years under the hypothesis that AD genetic risk factors exert their effects throughout the lifespan rather than only at later life stages. 37 The authors categorized participants as either APOE ε4 carriers or non‐carriers and found that APOE ε4 was associated with lower hippocampal volumes early in life, creating an initial offset. However, they found no significant interactions between APOE and age that would indicate faster hippocampal atrophy in older age. In contrast, we find no differences in hippocampal volume in those under the age of 60, and we provide compelling evidence for such interactive effects in older age. This is noteworthy given that structural MRI indicators of neurodegeneration are considered an advanced‐stage biomarker of AD. 3 , 38
