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LIT-915: One Giant Leap from Mouse to Man: The Microbiota–Gut–Brain Axis in Mood Disorders and Translational Challenges Moving towards Human Clinical Trials

2 min read

Properties6
StatusActive — read in full 2026-10-11 (NOTE-703) from the open-access text in Europe PMC (PMC8840472). Worth reading for the gap between mouse and human in microbiota–gut–brain research on mood: strong rodent effects, partial transfer of a depressive phenotype by faecal transplant into rodents, and repeated failures of preclinical probiotic effects to replicate in human trials. Note the source: all four authors were employed by a company that sells probiotics, and the review is narrative.
Tagspsychopathology-and-treatment, emotion-and-affect, ecology
SupportsCLAIM-166 — A lower-level collective within the composite person, such as the gut microbiome, can at times drive higher-level behaviour and even experience: the routes exist and the effects are causal in rodents, while the human evidence is modest
ReportsCASE-047 — Gut microbes and the host's hunger and mood: a lower-level collective that can drive the person
Cited as “paper” byNOTE-703 — Forssten et al. — One Giant Leap from Mouse to Man
Cited as “source” byTHEORY-560 — In rodents, gut microbes can drive stress and affect-related behaviour through vagal, immune, endocrine and metabolite routes, and faecal transplant from depressed people partly transfers the phenotype; in people, probiotics have so far shown at most small reductions in subjective stress in healthy volunteers, and strains with strong preclinical records have failed in controlled trials

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Sofia D. Forssten, Arthur C. Ouwehand, Shannon M. Griffin and Elaine Patterson (2022), Nutrients 14(3): 568 — doi:10.3390/nu14030568

Key takeaways

Read in full; see NOTE-703.

  • The route. “The vagus nerve is the most direct route of communication between the gut and the brain, thus enabling bidirectional communication.”
  • Animals. Faecal transplants from depressed patients into rodents produce behavioural abnormalities, “indicating at least partial transfer of the clinical psychiatric phenotype”. But “the gut microbiome is the only humanized component of the rodent”.
  • Humans. “A recent meta-analysis demonstrated that probiotic consumption could result in a reduction of subjective stress levels in healthy volunteers”. Strains with strong preclinical evidence have failed in trials. For L. rhamnosus JB-1: “not found to have an effect on mood, anxiety, stress, sleep quality, memory performance, attention, or anti-inflammatory cytokine levels compared with the placebo.”

Standing in the record

Filed on 2026-10-11 as evidence for the owner’s example, in CLAIM-166 and CASE-047, that the gut microbiome can influence affect and experience. The conflict of interest is quoted in the NOTE. The review reports its own failures in detail, which counts in its favour as a source on how weak the human evidence is. psychopathology-and-treatment comes first, as a review of interventions for mood disorders. Not held in the anthology.

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