As the brain ages, its internal sanitation system does not merely slow — it reorganizes, shifting from quiet, efficient clearance at the tissue's edges toward a more embattled, inflammatory response from within. Researchers studying aging and Alzheimer's-prone mice have traced this transformation across the lifespan, finding that the same glial structures meant to protect the brain may, over time, become markers of its mounting vulnerability. The discovery invites a reframing of Alzheimer's disease — not solely as a story of toxic protein accumulation, but as a failure of the brain's ability t