Gut Bacteria Linked to Cognitive Decline

Researchers have identified a mechanism by which intestinal interoceptive dysfunction, driven by specific gut bacteria, contributes to age-associated cognitive decline in mice. Published in Nature, the study indicates that an accumulation of medium-chain fatty acid-producing gut bacteria, such as *Parabacteroides goldsteinii*, triggers peripheral myeloid cell inflammation via GPR84 signaling.

This process impairs vagal afferent neurons, weakening gut-brain communication and leading to reduced neuronal activation in the hippocampus and memory encoding deficits.

The research demonstrated that interventions targeting this pathway, including phage therapy against *Parabacteroides*, GPR84 inhibition, and restoration of vagal activity, enhanced memory function in aged mice. These findings suggest that stimulating gut-brain communication through 'interoceptomimetics' could counteract age-related memory loss.

The study provides a detailed map of microbiome aging and its functional consequences, highlighting the gut-brain axis as a critical factor in brain aging.