In one sentence
Gut microbes may relate to children’s brain development and behaviour — including patterns seen in autism — but the evidence is still too uneven to justify microbiome “fixes” as treatment.
What the researchers did
This systematic review gathered epidemiological studies on the gut microbiota and neuropsychological development or behaviour from birth to age 18. Searching MEDLINE, Scopus, and Web of Science, the authors included 78 studies covering clinical neurodevelopmental conditions and general-population outcomes. They summarised microbiome findings, noted metabolomic clues, and judged study quality and design (including how often confounders such as diet and medication were handled).
What they found
- Across 23 autism studies, microbiome community structure often differed from typically developing peers: higher Clostridium and Sutterella, lower Blautia, Lactobacillus, and Bifidobacterium were frequently reported.
- Functional and metabolomic analyses pointed toward immune and neuroactive pathways; short-chain fatty acids such as propionate and valerate were elevated in some autism samples.
- Seven ADHD studies were less consistent — no clear bacterial signature.
- In the general paediatric population, associations were modest; Veillonella and Bifidobacterium appeared more often in children with stronger neuropsychological scores.
- Only 42% of studies were longitudinal, limiting causal claims.
What this means for families and therapists
- Do not treat this as proof that probiotics, restrictive diets, or commercial microbiome tests will improve autism or ADHD outcomes.
- Behavioural and developmental supports remain the best-evidenced foundation; gut health is at most an open research question.
- Ask clinicians what — if anything — is evidence-based for your child, and be cautious of costly unvalidated microbiome products.
Limitations and what we don't know yet
- Most of the 78 studies were rated poor or fair quality, often due to technical and statistical weaknesses.
- Heterogeneous designs, outcomes, and microbiome methods make direct comparison hard.
- Confounders (diet, medication, lifestyle) were frequently under-addressed.
- The review summarises associations; it does not show that changing the microbiome improves symptoms.
This is a plain-language summary of The relationship between the gut microbiota and neuropsychological development and behaviour during childhood and adolescence: a systematic review of epidemiological studies by Jimenez-Arenas P, Ferrer M, Ruiz-Rivera M et al., Brain, behavior, & immunity - health (2026). Source license: CC-BY-NC-ND. It is not medical advice — talk to a qualified clinician before changing therapy.