Researchers discover mid-life immune cell changes in the human hippocampus

A research team led by scientists from the University of California, San Diego, the New York Genome Center, and the University of California, Irvine, has identified a previously unknown change in the human brain occurring during mid-life. The study, funded by the U.S. National Institutes of Health (NIH), analyzed post-mortem hippocampus tissue from 40 individuals aged between 20 and 95 who had no history of neurological diseases. Findings reveal that the population of microglia, the brain's primary immune cells, begins to undergo significant alterations starting around age 50.

Previously, the scientific consensus held that microglia, which originate during embryonic development, remain constant and continuously renew throughout a person's lifespan. However, the new analysis contradicts this, showing a gradual decline in the number of these cells in the hippocampus between the ages of 50 and 75. This discovery provides new insights into the mechanisms of aging and the progression of dementia, challenging long-standing beliefs regarding neuro-immunology. Further research is expected to continue building on these findings to better understand the role of these cellular shifts in age-related cognitive decline.