Using a retrospective analysis of multiple prospective, longitudinal aging studies, OBAS, ISAAC, KEAP, AADAPt, CBDP, OLL, and the Layton Alzheimer’s Disease Center patient registry, we have shown that APOE4+ men have an increased rate of decline in cognition after exposure to surgery and anesthesia than women APOE4 carriers. Here, APOE is linked to Alzheimer disease.