For generations, Alzheimer's disease announced itself only after the damage was already deep — confirmed through spinal taps and brain scans that came too late for much to be done. Now, a blood test born from decades of neuroscience research at Washington University has received FDA clearance, offering physicians a simple, accurate way to detect the disease's biological fingerprints before the full weight of cognitive decline arrives. The approval of PrecivityAD2 arrives precisely as the first drugs capable of slowing Alzheimer's progression reach patients — drugs that work best when given ear