AD is the most common dementia in humans and over the next decades will account for a major and increasing morbidity and mortality in the US and worldwide. AD is usually a sporadic disease and the commonly accepted hypothesis as to its etiology is the amyloid cascade hypothesis. There is tremendous activity in the pharmaceutical industry and academia directed towards development of disease modifying treatments, most commonly targeting amyloid, but also tau and other mechanisms. Most efforts are directed towards Mild to Moderate AD or prodromal AD with relatively little work on prevention of AD due to various challenges, including identification of healthy people who would be treated.