Nearly 30 years ago, when the first effective Alzheimer’s drugs were approved, optimism was in the air. True, the drugs didn’t slow the underlying disease, but they made a meaningful difference to symptoms. It seemed like disease-modifying drugs would be coming any day. “The story was, within a few years, we should have drugs that will actually interfere with disease processes,” says Rob Howard, a professor of old-age psychiatry at University College London. “We didn’t realize we were going to have to wait more than 20.”