Hopeful Brains Even the brain without symptoms (a) might eventually develop Alzheimer disease, but people with a certain dominant gene definitely will. They have no symptoms in early adulthood (b), some symptoms in middle adulthood (c), and stage-five Alzheimer disease (d) before old age. Research finds early brain markers (such as those shown here) that predict the disease. This is not always accurate, but may soon lead to early treatment that halts AD, not only in those genetically vulnerable, but also in everyone.

TAMMIE BENZINGER, MD, PHD, TYLER BLAZEY, WASHINGTON UNIVERSITY SCHOOL OF MEDICINE IN ST. LOUIS