Finding in zebrafish may contribute to understanding cognitive decline of aging.

National Institutes of Health researchers studying zebrafish have determined that a population of cells that protect the brain against diseases and harmful substances are not immune cells, as had previously been thought, but instead likely arise from the lining of the circulatory system.

This basic science finding may have implications for understanding age-related decline in brain functioning and how HIV infects brain cells.

The study, appearing online in eLife, was conducted by researchers at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and National Human Genome Research Institute and the Japanese National Institute of Genetics.

The blood-brain barrier is the layer of cells that line the blood vessels of the brain. The inner cell layer that lines vessels, known as…