The articles included in this study were found using the keywords “Alzheimer disease”, “cholinergic”, “beta-amyloid”, “tau protein”, “excitotoxic”, “oxidative stress”, “APOE4”, GSK3, “CREB”, “type 3 diabetes”, “endocannabinoid system” and “hypothesis” combined with the Boolean OR operator, independently or together. This evidence concerns the gene APOE and Alzheimer disease.