In order to begin to elucidate the role of genetic factors and biological sex in the development of POCD, we investigated the associations of sex, APOE4 carrier status, and exposure to surgery/general anesthesia (GA) with postoperative cognitive decline in 1033 participants from several prospective longitudinal cohort studies of the Oregon Alzheimer’s Disease Center (OADC). The gene discussed is APOE; the disease is early-onset autosomal dominant Alzheimer disease.