For the past quarter century, scientists battled Alzheimer’s disease under a single guiding principle: that protein clumps—beta-amyloid—deposited outside sensitive brain cells gradually damage neuronal functions and trigger memory loss. The solution seems simple: remove junk amyloid, protect the brain. They could be completely wrong. Last month, Alzheimer’s disease defeated another promising near-market drug that tried to prevent or remove amyloid deposits, adding to the disease’s therapeutic “graveyard o
