NatureMar 12, 2026

Problems sensing gut signals may contribute to memory decline with aging

Longevity & Aging Weekly Brief ↗PubMed ↗DOI ↗OA ↗

Updated Jun 28, 2026

Abstract

Essence

Age-related gut-brain interoceptive dysfunction may help drive memory decline, and restoring that signaling improved memory in aged mice.

Evidence

This mechanistic mouse ageing study mapped lifespan microbiome changes and found that medium-chain-fatty-acid-producing bacteria such as Parabacteroides goldsteinii activated GPR84-linked myeloid inflammation, weakened vagal afferent signaling, impaired hippocampal activation, and that phage targeting, GPR84 inhibition, or vagal restoration improved memory in aged mice.

Caveat

The evidence is mechanistic and preclinical in mice, so whether the same pathway explains heterogeneous cognitive ageing in humans remains unproven.

Simplified

Ageing is accompanied by declining memory function, with extremely heterogeneous manifestation in the human population. Brain-extrinsic factors influencing cognitive decline, such as gastrointestinal signals, have emerged as attractive targets for peripheral interventions, but the underlying mechanisms remain largely unclear. Here, by charting a high-resolution map of microbiome ageing and its functional consequences throughout the lifespan of mice, we identify a mechanism by which inhibition of gut-brain signalling during ageing results in impaired neuronal activation in the hippocampus and loss of memory encoding. Specifically, accumulation of gut bacteria that produce medium-chain fatty acids, such as Parabacteroides goldsteinii, can drive peripheral myeloid cell inflammation through GPR84 signalling. As a result, the function of vagal afferent neurons is impaired, the interoceptive signal received by the brain is weakened and hippocampal function declines. We leverage this pathway to define interventions that enhance memory in aged mice, such as phage targeting of Parabacteroides, GPR84 inhibition and restoration of vagal activity. These findings indicate a key role for interoceptive dysfunction in brain ageing and suggest that interoceptomimetics that stimulate gut-brain communication may counteract age-associated cognitive decline. 1 2-6