Alzheimer’s disease (AD) pathology is thought to begin in the brainstem — the brain’s evolutionarily oldest part, which is vital for basic life functions, and, in humans, where tau first accumulates, slowly initiating the AD process. Cerebral microglia, the central nervous system’s most prominent immune cells — the first to respond when the brain goes awry — play a critical role in AD pathogenesis, yet little is known about brainstem microglia in AD. Translocator protein positron emission tomography (TSPO PET), which is sensitive to activated microglia, shows a high signal...
