Longevity & AgingAging Gut Bacteria Block Brain Signals and Erase Memories in Mice
Researchers at Penn and Stanford mapped how the aging microbiome drives cognitive decline. Certain gut bacteria that accumulate with age—especially Parabacteroides goldsteinii—produce medium-chain fatty acids that activate GPR84 receptors on immune cells, triggering inflammation. This inflammation impairs vagal afferent neurons, weakening the interoceptive signal reaching the brain. The result is reduced hippocampal activation and measurable memory loss in mice. Critically, the team showed that transferring an aged microbiome into young germ-free mice reproduced the memory deficits, while interventions including phage therapy targeting Parabacteroides, GPR84 inhibition, and vagal stimulation each restored memory in old mice—pointing to actionable, peripheral targets for treating age-related cognitive decline.
