Clearing amyloid plaques may break the chain reaction that fuels brain cell destruction in Alzheimer’s disease. One Alzheimer’s brain offered researchers something they almost never get to see: a natural side-by-side experiment. Clinical trials can track memory, brain scans, and biological markers, but they cannot usually show exactly what happened inside individual brain regions over many years. It allowed us to directly compare what happened next in neighboring brain regions and better understand the relationship between amyloid, tau, and neurodegeneration.” Researchers now want to understand why the drug cleared plaques more effectively from some brain regions than others.