APOE and Alzheimer disease: CVD and Alzheimer dementia are multifactorial diseases that also share common disease mechanisms because of an overlap in genetic104 and biological risk factors, which together increase the risk for CI and dementia.105 The APOE gene is polymorphic and encoded by 3 major alleles: APOE‐ε2, APOE‐ε3, and APOE‐ε4.