An estimated 50 million people around the world have Alzheimer’s disease (AD), and perhaps twice that number are unknowingly “incubating” the disease during its long presymptomatic period. The total cost of caring for AD patients in the U.S. exceeds that for all cases of heart disease or cancer. Yet there is only one disease-modifying therapy approved in the U.S. (but not elsewhere), and controversy surrounding both its target, amyloid, and its efficacy has severely limited its use.