Changes in the Gut Microbiota of Children with Autism Spectrum Disorder Original paper

What was studied?

This study investigated gut microbiota in children with ASD, using 16S rRNA gene sequencing to compare fecal microbial composition between 48 Chinese children diagnosed with autism spectrum disorder and 48 healthy neurotypical controls. The authors examined microbial richness, diversity, taxonomic shifts across phylum-to-species levels, and predicted microbial functional pathways. By integrating sequencing data with community and metabolic analyses, the study aimed to identify microbial signatures linked to ASD, including shifts in short-chain fatty acid (SCFA) producers, branched-chain amino acid (BCAA) synthesizers, and mucin-degrading species. The paper further evaluated how altered microbial metabolic pathways—particularly tryptophan and lysine metabolism—may contribute to ASD-related gastrointestinal and neurobehavioral features.

Who was studied?

The study enrolled 96 children aged 2–7 years, including 48 diagnosed with ASD according to DSM-IV-TR criteria and validated clinical tools (ADI-R, CGI-S, ABC-I). Children with comorbid psychiatric disorders, recent probiotic/antibiotic use, metabolic diseases, or neurodevelopmental conditions such as Rett syndrome or Asperger’s disorder were excluded. The control group consisted of 48 healthy, age-matched neurotypical children without allergies and with no history of GI or neurodevelopmental disorders. Stool samples were parent-collected at home, transported within three hours, and stored at −80°C prior to sequencing. This homogenous sampling approach strengthened the comparison between ASD and neurotypical children.

Most important findings

Children with ASD demonstrated markedly altered microbial structures characterized by increased richness and diversity. At the phylum level, Bacteroidetes were elevated while Firmicutes, Proteobacteria, and Verrucomicrobia were reduced. The Bacteroidetes/Firmicutes ratio was more than doubled in ASD. Genus-level increases included Bacteroides, Prevotella, Megamonas, and Lachnospiracea_incertae_sedis, whereas beneficial taxa such as Clostridium IV, Clostridium XIVa, Dialister, Akkermansia, Haemophilus, and Escherichia/Shigella were significantly reduced. Species-level analysis showed increases in Bacteroides vulgatus and Prevotella copri—key BCAA producers—as well as R. faecis, B. coprocola, and E. eligens. Notably reduced species included B. fragilis and A. muciniphila, both associated with mucosal barrier health and immunomodulation. Functional predictions revealed only one pathway—cellular antigens—enriched in ASD, while essential metabolic pathways (lysine degradation, tryptophan metabolism, xenobiotic degradation, fatty acid biosynthesis) were reduced. These metabolic disruptions suggest impaired neurotransmitter regulation and gut barrier function.

Key implications

The study strengthens evidence that gut microbial imbalance contributes to ASD pathophysiology, highlighting increased BCAA-producing species that may influence excitatory neurotransmitter pathways, and decreased butyrate-producing and mucin-degrading microbes that normally support gut integrity and immune regulation. Reduced tryptophan and lysine metabolism may impair serotonin synthesis and neuroimmune function, providing mechanistic links to behavioral and gastrointestinal symptoms. These findings underscore the therapeutic potential of microbiome-targeted interventions, including species-level personalization, given the high inter-individual variability observed among ASD children.

Citation

Zou R, Xu F, Wang Y, et al. Changes in the gut microbiota of children with autism spectrum disorder.Autism Research. 2020;1–12. doi:10.1002/aur.2358.