An interesting Social media post.
Researchers led by Dr. Christoph A. Thaiss at Stanford University and the Arc Institute investigated how aging affects the gut-brain connection in mice, focusing on age-related changes in the gut microbiome to identify ways to prevent memory loss in humans. Old mice performed worse on memory tasks than young mice. Young mice with microbiomes altered to resemble those of old mice—achieved by co-housing young and old mice for a month or transplanting gut bacteria from old to young mice—also performed worse on memory tasks compared to young mice with young microbiomes. Treating old mice and young mice with old microbiomes with antibiotics to deplete gut bacteria improved their performance on memory tasks. Analysis of microbiomes showed that Parabacteroides goldsteinii exhibited the largest increases during aging. Mice exposed specifically to these bacteria performed worse on cognitive tests. These bacteria produced large amounts of a certain type of fatty acid, which, when fed to mice, led to cognitive decline. These fatty acids drove inflammation in myeloid cells, a type of white blood cell. This inflammation impaired signaling from the gut to the brain via the vagus nerve, which connects various organs, including the digestive tract, to the brain. The weakened signal reduced activity in the hippocampus, a brain region responsible for short-term memory, and disrupted activity in other brain regions involved in processing sensory information. Three approaches restored vagus nerve signaling and improved cognitive performance in aged mice: treating with bacteria-killing viruses, blocking inflammation, and chemically activating the vagus nerve. Thaiss stated: “We tend to think of memory decline as a brain-intrinsic process. But this study indicates that we can enhance memory formation and brain activity by changing the composition of the gastrointestinal tract—a kind of remote control for the brain.” The study indicates that manipulating gut-brain communication during aging may be an attractive strategy to treat cognitive decline, but more research is needed to learn how age-related changes in the gut develop and how they influence brain health.