Imbalance in the Gut Microbiota of Children With Autism Spectrum Disorders Original paper

What was studied?

This study investigated gut microbiota imbalance in ASD by analyzing fecal microbial composition in children diagnosed with autism spectrum disorder compared with healthy peers. Using 16S rRNA V3–V4 sequencing, the authors mapped microbial diversity, relative abundance, and taxonomic differences to determine whether gastrointestinal symptoms and microbial alterations were linked to ASD. The investigation explored alpha and beta diversity, performed principal coordinate analysis, and used LEfSe to identify discriminatory taxa. Visual data such as the rarefaction curves on page 4 and the phylum-level bar charts on page 6 highlight notable abundance differences between Actinobacteria, Firmicutes, and Bacteroidetes. The work aimed to clarify whether distinct microbial signatures could serve as biomarkers or potential mechanistic contributors within the microbiota–gut–brain axis.

Who was studied?

The study evaluated 25 children with ASD and 20 healthy controls recruited from Shengli Oil Field Central Hospital in China. All participants were of Han Chinese ethnicity and between roughly five and six years of age. Children with ASD were diagnosed using DSM-5 criteria and assessed with the Autism Treatment Evaluation Checklist. Gastrointestinal symptoms were documented using the GI Severity Index, revealing frequent constipation, abdominal pain, and diarrhea among ASD participants. Importantly, no children had used antibiotics, probiotics, or related medications within six months before sampling, reducing potential confounding effects on microbiome structure. Fresh fecal specimens were collected, stored at –80°C, and processed for DNA extraction and sequencing to ensure high-quality microbial profiling.

Most important findings

Children with ASD exhibited gut microbiota imbalance in ASD characterized by distinct taxonomic shifts rather than major changes in overall species richness. Alpha diversity indices (Shannon, Chao1, ACE) showed no significant group differences, yet beta diversity analysis demonstrated clear clustering separation, indicating altered community structure (page 5 PCA plot). Several genera—including Faecalibacterium, Prevotella, Subdoligranulum, and Ruminococcus—were more abundant in ASD, whereas Bifidobacterium was reduced. At the phylum level, ASD children showed higher Firmicutes and lower Actinobacteria relative to controls (page 6 phylum-level comparison). LEfSe results identified Ruminococcaceae and Firmicutes as ASD-enriched, while Actinobacteria taxa characterized controls. These shifts highlight altered butyrate-associated organisms, disruptions in SCFA-producing profiles, and changes that may influence immune signaling, intestinal barrier integrity, and gut–brain communication.

Key implications

The findings reinforce robust connections between gastrointestinal symptoms, microbial dysbiosis, and autism-related behavioral severity. Reduced Bifidobacterium levels, combined with elevated Faecalibacterium and Subdoligranulum, underscore potential disturbances in anti-inflammatory and metabolic pathways influencing neurodevelopment. The authors propose that gut microbiota could serve as future biomarkers and therapeutic targets, although population-specific factors such as geography and diet warrant caution when generalizing. Interventions aiming to modulate gut microbial composition—particularly strategies restoring beneficial Actinobacteria—may hold promise in managing ASD-associated symptoms.

Citation

Ding H, Yi X, Zhang X, Wang H, Liu H, Mou WW. Imbalance in the gut microbiota of children with autism spectrum disorders. Front Cell Infect Microbiol. 2021;11:572752. doi:10.3389/fcimb.2021.572752