Alzheimer's disease affects at least five and a half million people in the United States. One of the greatest challenges in trying to treat the disease is catching it early enough. There's currently no reliable way to diagnose Alzheimer's until symptoms like memory loss are already recognizable. And by that time the brain has suffered years if not decades worth of damage. That's likely why many promising drug trials in recent years have failed. But a test capable of diagnosing Alzheimer's years