University of California San Francisco Medical Center Jul 9 2025 It's been recognized for some time that Alzheimer's disease affects brain regions differently and that tau - a protein known to misbehave - plays an important role in the disease. Normally, tau helps stabilize neurons, but in Alzheimer's disease, it begins to misfold and tangle inside neurons. It spreads across the brain forming toxic clumps that impair neuronal function and ultimately lead to cell death. Brain areas like the