"The study aimed to show that Alzheimer’s disease could be stopped if treatment began before symptoms emerged. The participants were the best candidates that scientists could find: still healthy, but with a rare genetic mutation that guaranteed they would develop dementia.
Now, the verdict is in: The drugs did nothing to slow or stop cognitive decline in these subjects, dashing the hopes of scientists.
The results are a deep disappointment, scientists said — but not a knockout punch. The drugs did not work, but the problems may be fixable: perhaps the doses were too low, or they should have been given to patients much younger."