As the human brain ages, its immune cells get swapped out for new ones
Scientists studied the aging human hippocampus, a brain area key for memory. They found that between ages 50 and 75, the brain's original immune cells are lost and replaced by cells that resemble ones from the blood.
Why it matters
The hippocampus helps us form and keep memories, and it changes a lot as we grow old. This work maps what actually happens inside its cells over a lifetime, including a big drop in support cells and a change in the brain's immune cells. Understanding these steps could one day help explain why memory fades with age, though this is basic biology and not yet a treatment.
Who's behind it: Nathan R. Zemke, Bing Ren and colleagues, University of California (San Diego and Irvine) and collaborators.
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