Our study takes advantage of the large sample size of the UKB neuroimaging cohort to build upon existing knowledge by examining the effects of categorized APOE genotypes in community‐based individuals without dementia. In a recent UKB‐based cross‐sectional study, Veldsman et al. analyzed hippocampal volume trends across age and APOE, and our findings are consistent with their results. 35 In addition, they concentrated solely on ε3/ε4 and ε4/ε4 carriers given established reductions in hippocampal volume. In our analysis, we include ε2/ε3 heterozygotes. This broader approach is warranted given the large sample of ε2/ε3 carriers in the UKB and previously reported opposing effects of APOE ε4 and ε2 alleles on hippocampal morphology. 9
