Scientists Found a Hidden Tipping Point That Decides Who…

Scientists Found a Hidden Tipping Point That Decides Who Gets Dementia and Who Doesn't More than 55 million people worldwide live with Alzheimer's disease, yet some people accumulate substantial amyloid plaques and tau tangles in their brains and remain completely cognitively healthy. A major new study published in Nature Medicine may finally explain this long standing puzzle, and it centres on the brain's own immune cells. Alzheimer's pathology and actual dementia symptoms don't always match up. This has pushed researchers to look beyond simply measuring how much plaque and tangle buildup exists, toward understanding how the brain's cells actually respond to that buildup. Researchers analysed donated brain tissue from three groups, older adults with dementia, older adults without dementia despite having Alzheimer's pathology, and remarkably, cognitively healthy centenarians, people who had lived past 100 with their mental faculties intact. Using advanced techniques that examine tissue at the level of individual cells, researchers mapped exactly how the brain's resident immune cells, called microglia, behaved differently across these groups. The researchers identified six distinct tissue regions representing different stages of Alzheimer's progression. One particular transition stood out, the shift from regions dominated by amyloid plaques to regions where tau pathology and actual brain cell damage tak