APOE and Alzheimer disease: Limitations of this study include its cross‐sectional nature and the number of cases examined within each of the groups investigated; late onset AD cases homozygous for APOE4 were also at more advanced Braak stages (V and VI) compared to those homozygous for APOE3 (Braak stages IV and V), and our case numbers were underpowered to stratify findings by sex.