Hidden brain immune shift begins around age 50, NIH-funded study finds
A new NIH-funded study of postmortem hippocampal tissue found that the brain's original immune cells decline sharply between ages 50 and 75, replaced by more inflammatory cells resembling those found in blood. The findings, published in Science, could reshape how researchers unde
Researchers from UC San Diego, the New York Genome Center, Columbia University and UC Irvine analyzed postmortem hippocampal tissue from 40 neurologically healthy adults aged 20 to 95. They found that microglia, the brain's resident immune cells present since before birth, decline sharply between roughly age 50 and 75, replaced by cells with stronger inflammatory signals that resemble immune cells circulating in the blood. Cells that maintain the blood-brain barrier also declined, and the genome's 3D structure became progressively less organized with age across multiple brain cell types. The study, funded by the National Institutes of Health and published in the journal Science, challenges the long-held assumption that microglia simply renew themselves for life without outside help, and could point toward new therapeutic targets for neurodegenerative disease.