Whether they remain free of diagnosable disease or become afflicted by dementia, our brains inevitably change as we grow older. Our cells degenerate, we forget names, and we think more slowly, making hard to distinguish normal aging from the warning signs of brain disease. Programs that claim to keep the brain healthy are popular, but it is not clear how much physical and mental exercise and good nutrition really help. When will rigorous research give us meaningful ways to prevent dementia or arrest its progression at the very earliest stages? What important clinical trial results can we anticipate in the coming years?