Alzheimer’s, medical experts now agree, starts a decade or more before people have symptoms. And by the time there are symptoms, it may be too late to save the brain. So the hope is to find good ways to identify people who are getting the disease, and use those people as subjects in studies to see how long it takes for symptoms to occur and in studies of drugs that may slow or stop the disease.
However, the article goes on to raise the question: since we don't have any reliable treatment for the disease, what's the point of undergoing a possibly painful or at least uncomfortable test to confirm that you've got it?
Thanks to Derek Colanduno of Skepticality for directing my attention to this article.