Exploring the interplay between gut microbiota and clinical parameters of autism spectrum disorder

Background: Emerging evidence suggests that gut microbiota may have a key influence in the pathophysiology of autism spectrum disorders (ASD). This study investigates the differences in the composition of gut microbiota between ASD children and their neurotypical peers and the link between gut microbiota and different clinical scales. Methods: A total of 35 ASD children and 35 typically developing (TD) children were included in this study. Stool specimens were analyzed utilizing quantitative SYBR Green-based real-time polymerase chain reaction (qPCR) targeting the 16S ribosomal RNA (rRNA) gene to characterize gut microbiota composition. The severity of autism spectrum disorder (ASD) symptoms was evaluated using the Childhood Autism Rating Scale (CARS). Sensory processing abnormalities were assessed through the Short Sensory Profile (SSP), while gastrointestinal (GI) symptomatology was measured using a modified version of the six-item Gastrointestinal Severity Index (6-GSI) questionnaire. Furthermore, the Social Communication Questionnaire (SCQ) and the Autism Treatment Evaluation Checklist (ATEC) were utilized as supplementary tools for the evaluation of ASD symptoms and treatment response. Results: Our results revealed significant compositional changes in the gut microbiota of ASD children. At phylum level analysis, Bacteroidetes were significantly higher in ASD than TD children (p>0.001). In contrast Firmicutes to Bacteroidetes (F/B) ratio was lower in ASD children (p>0.001). At the genus level, the relative abundances of Bacteroides and Ruminococcus were significantly elevated in children with autism spectrum disorder (ASD) (p > 0.001 and p = 0.035, respectively), whereas the Prevotella to Bacteroides ratio (P/B ratio) was significantly reduced in the ASD group (p > 0.001). At the species level, the relative abundance of Desulfovibrio was significantly lower in children with ASD compared to typically developing controls (p = 0.023). No statistically significant differences were observed between the ASD and TD groups in the relative abundances of Lactobacilli, Bifidobacteria, Akkermansia muciniphila, Faecalibacterium prausnitzii, Clostridium difficile, Sutterella, and Bacteroides fragilis. Conclusion: These findings suggest that dysbiosis in the gut microbiota was associated with ASD clinical parameters, potentially contributing to the patients’ gastrointestinal and behavioral symptoms.