Note: Single-source report; awaiting corroboration.
A National Institutes of Health (NIH)-supported study reports significant changes in immune cell composition within the hippocampus—a key brain region for learning and memory—beginning in midlife. Researchers suggest these changes may contribute to age-related cognitive decline and increased dementia risk.
The research team, including scientists from the University of California at San Diego, the New York Genome Center, and UC Irvine, analyzed postmortem hippocampal tissue from 40 neurologically healthy adults aged 20 to 95 years using advanced single-cell and epigenomic techniques.
Findings revealed that the brain’s primary immune cells, microglia, progressively decrease between ages 50 and 75. These cells appear to be replaced by immune cells with elevated inflammatory features similar to peripheral blood-derived cells, challenging previous assumptions about microglial longevity.
Gene expression and epigenetic analyses showed a major shift in immune cell lineage and identity, undetectable by gene expression data alone. Additionally, cells maintaining the protective blood-brain barrier deteriorated with age, alongside widespread genome architecture disruptions across many brain cell types.