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A small, exploratory study from Comenius University in Slovakia finds overlapping gut microbiome changes in children with autism, ADHD and anorexia nervosa. Using stool samples from 117 young participants, researchers detected shared shifts in bacterial groups that have been tied to inflammation, metabolism and appetite regulation — a pattern that raises questions about cause, consequence and clinical potential.
A surprising microbial overlap across very different conditions
The research compared stool samples from 30 boys with autism spectrum disorder (ASD), 21 girls with anorexia nervosa (AN), 14 children with attention deficit hyperactivity disorder (ADHD) and a matched control group of neurotypical children. While each condition has distinct behavioral and clinical features, the teams found notable similarities in gut-microbe composition across the three disorder groups.
One clear signal was a higher ratio of Bacteroidetes to Firmicutes in children with ASD, ADHD and AN compared with controls. This Bacteroidetes/Firmicutes balance is often discussed in microbiome studies because shifts in these dominant phyla have been associated with inflammation, glucose metabolism and mechanisms that influence satiety.
Key microbial changes and what they might mean
Beyond phylum-level differences, the study identified more specific taxa that differed between groups. Both ADHD and autism groups showed reduced species richness — meaning fewer distinct microbial species — a feature commonly linked to less resilient gut ecosystems.
- Escherichia: Elevated levels were measured across several patient groups. Escherichia species can live harmlessly in the gut at low numbers but may contribute to problems when they expand or colonize the wrong niche.
- Desulfovibrio: More abundant in children with ADHD and girls with anorexia nervosa. These sulfate-reducing bacteria thrive in low-oxygen, nutrient-poor environments and can alter gut chemistry when overrepresented.
- Faecalibacterium: Lower levels were found in ADHD and AN groups. Faecalibacterium is usually abundant in healthy guts and is linked to anti-inflammatory effects; its depletion has been reported in inflammatory bowel conditions and in some mood disorders.
Collectively, the pattern — increased Bacteroidetes, decreased Firmicutes, reduced diversity and specific enrichments or depletions — resembles microbial signatures seen in certain inflammatory states, hinting at possible gut–immune–brain connections.
Diet, behavior and the two-way gut–brain loop
The authors emphasize that diet strongly shapes microbiome diversity. Children with autism and ADHD commonly show picky, sensory-driven eating behaviors that reduce dietary variety. For anorexia nervosa, intentional restriction is a diagnostic hallmark. Limited or repetitive diets can therefore drive similar microbial shifts across otherwise different conditions.
But the relationship is not one-way. Microbiome changes can influence metabolism, inflammation and neural signaling — potentially worsening psychiatric or behavioral symptoms. That creates the possibility of a positive-feedback loop: behavior shapes the gut, and the altered gut may reinforce behavior or mood changes.
Study limitations and cautious interpretation
Important caveats temper the findings. The study’s sample size was modest (117 participants) and uneven across groups, problems that were amplified by COVID-19 disruptions and difficulties obtaining stool samples from some children. These factors limit statistical power and the ability to generalize results.
The researchers explicitly note it remains unclear whether observed microbiome profiles contribute to neurodevelopmental and eating disorders, result from them, or reflect a combination of both. Replication in larger, longitudinal cohorts — ideally combining dietary records, metabolic markers and behavioral measures — will be needed to clarify directionality and mechanism.
Implications for diagnosis and treatment
If replicated, consistent microbiome signatures could eventually support earlier diagnosis, personalized nutrition strategies or adjunctive microbiome-targeted therapies (for example, specific prebiotics, probiotics or dietary interventions). However, the authors caution that practical applications are premature given current evidence.
Expert Insight
Dr. Elena Novak, a fictional pediatric neurogastroenterologist, comments: "This study is a valuable hint that different neurobehavioral conditions may converge on shared gut microbial features. It reinforces why clinicians should consider diet and gut health as part of comprehensive care. Still, we need larger, carefully controlled studies before changing clinical practice."
The study, published in Neuroscience, adds to a growing body of research exploring how microbial ecosystems interact with the developing brain. For families and clinicians, the current takeaway is cautious curiosity: the gut matters, but the story is far from fully written.
Source: sciencealert
Comments
mechbyte
My nephew with ASD eats like a bird and docs mentioned gut stuff before, this kinda validates it and also freaks me out 🙂 hope they do follow ups, pronto
bioNix
Wait, is this even causal? Picky diets could explain a lot. Gut-brain loop is tempting but we need much bigger, longitudinal studies. Not convinced tho, curious.
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