The role of cholesterol in AD pathology is poorly understood; however, the strongest genetic risk factor for AD, APOE, is a key transporter of extracellular cholesterol in humans, and several other Alzheimer’s risk genes, including clusterin (Apolipoprotein J), ABCA7 and ABCA1, are involved in cholesterol transport and regulation. Here, ABCA1 is linked to Alzheimer disease.