Midlife brain-immune shift linked to dementia risk
New research finds that around age 50 the brain’s protective microglia decline and are replaced by inflammatory cells from the blood, a shift that may raise dementia risk, including Alzheimer’s, and is accompanied by deterioration of the blood–brain barrier and widespread DNA/gene changes. The study analyzed postmortem hippocampal tissue from 40 adults across ages 20–95, a small, early-stage look that cannot prove causation but suggests a possible mechanism and potential for blood-derived immune cells to be targeted for future therapies. The work, funded by NIH and published in Science, highlights variability in brain aging and the need for further research into triggers and modifiers of this immune-cell replacement.
