Walnut Peptide Reverses Age-Related Memory Loss by Reshaping the Gut-Brain Axis

Cognitive decline in aging is increasingly understood as a systemic problem involving gut dysbiosis, chronic inflammation, and neuroinflammation — all linked through the gut-brain axis. Finding safe, food-derived compounds that target these overlapping pathways is a major focus of longevity research. This study introduces a recombinant form of a previously identified walnut peptide as a potential multi-target therapeutic.

Researchers expressed and purified rWDP — a recombinant version of the walnut-derived peptide EVSGPGYSPN — from an E. coli system, then administered it to mice in which accelerated aging was induced via chronic d-galactose injection. Cognitive function was assessed using the Morris water maze, a gold-standard test for spatial learning and memory.

rWDP treatment produced significant memory improvements alongside several favorable biological changes. Gut microbiota composition shifted positively, notably with increased Akkermansia muciniphila — a bacterium strongly associated with metabolic and gut health. Colon mucosal integrity improved, and systemic inflammatory markers including IFN-γ and VCAM-1 declined. In the brain, microglial activation was reduced and hippocampal neurons were better preserved. Lower p21 expression in the hippocampus and cortex suggests a reduction in cellular senescence. In vitro experiments confirmed rWDP suppressed LPS-induced nitric oxide and pro-inflammatory gene expression in microglial cells.

Metabolomic data pointed to restored neurotransmitter homeostasis, with higher levels of 5-hydroxyindoleacetic acid (a serotonin metabolite), kynurenine, and glutathione — suggesting both anti-oxidative and neuromodulatory effects.

While the findings are promising, this remains a preclinical mouse study using an accelerated aging model. Bioavailability, dosing, and safety in humans require further investigation before any clinical translation.