"Ten years ago people talked confidently of stopping Alzheimer’s disease in its tracks. Now, they realise they have no idea how to do that," says The Economist. "At the turn of the century, Alzheimer’s research seemed promising. A flurry of drugs which treated symptoms of the disorder had just hit the market and researchers were setting out confidently on a deeper investigation of its causes. Understanding those, they felt sure, would result in a cure. It still might, but the truth is that the hoped-for understanding has not come. As a consequence, a long list of would-be cures have failed in late-stage clinical trials, at enormous cost to the companies producing them."