Gut microbiota changes in patients with autism spectrum disorders Original paper

What was studied?

This study examined changes in gut microbiota in children with autism spectrum disorder (ASD), focusing on how microbial diversity and specific bacterial signatures differ from those in healthy controls. The research evaluated 16S rRNA V4-region sequencing of stool samples to identify microbiome patterns associated with ASD and explored microbial biomarkers that can distinguish ASD from typical development. It also analyzed functional metabolic pathways predicted from microbial gene content, adding insight into how gut microorganisms might influence neurodevelopment.

Who was studied?

The study included 127 children aged 2–7 years: 77 diagnosed with ASD and 50 age-matched healthy controls. ASD severity was categorized using the Childhood Autism Rating Scale into mild (n=33) and severe (n=44). Groups were similar in age, sex, delivery mode, feeding patterns, diet variety, and habitation. None had used antibiotics, probiotics, or other microbiota-altering medications for at least one month prior to sampling, allowing the analysis to focus on intrinsic microbiome features rather than medication effects.

Most important findings

Children with ASD exhibited significantly higher microbiota richness, biomass, and alpha diversity than healthy controls. Principal coordinate analyses showed that ASD and control microbiota clustered distinctly, indicating a clear shift in community structure. Numerous taxonomic changes emerged. At the genus level, children with ASD showed increased unidentified Lachnospiraceae, unidentified Clostridiales, unidentified Erysipelotrichaceae, Dorea, Collinsella, and Lachnoclostridium. In contrast, Bacteroides, Faecalibacterium, Parasutterella, and Paraprevotella were consistently reduced. Severity analyses demonstrated that greater ASD symptom burden correlated with higher unidentified Lachnospiraceae and Erysipelotrichaceae, and lower Faecalibacterium, three taxa linked to butyrate metabolism, gut barrier support, and immune signaling. A random-forest model identified Faecalitalea, Caproiciproducens, and Collinsella as strong microbial markers, generating an AUC of 0.94–0.98 for distinguishing ASD from healthy children. Functional predictions suggested increased galactose metabolism, glycosyltransferase activity, glutathione metabolism, and antifolate resistance in ASD, while healthy controls showed enrichment of mitochondrial biogenesis, pyruvate metabolism, and nucleotide excision repair pathways.

Key implications

This large-sample analysis supports the view that ASD is associated with a distinctive gut microbiome signature characterized by increased microbial diversity, enrichment of taxa implicated in altered short-chain fatty acid metabolism, and depletion of beneficial commensals such as Faecalibacterium. Microbiome shifts appear linked to ASD severity, suggesting a potential contribution to symptom expression via gut–brain signaling, immune modulation, or metabolic outputs. The identification of highly predictive microbial biomarkers underscores the promise of microbiome-based diagnostics and future interventions, although causal relationships remain unproven. These findings reinforce the potential role of targeted microbiota modulation as an adjunctive therapeutic strategy for ASD.

Citation

Ding X, Xu Y, Zhang X, et al. Gut microbiota changes in patients with autism spectrum disorders.Journal of Psychiatric Research. 2020;129:149-159. doi:10.1016/j.jpsychires.2020.06.032