Gut Microbiota and Autism Spectrum Disorders: Neurodevelopmental, Behavioral, and Gastrointestinal Interactions

Background: Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by social communication deficits, repetitive behaviors, and frequent gastrointestinal comorbidities. Emerging research suggests gut microbiota alterations contribute to ASD symptoms and gastrointestinal dysfunction, but detailed microbial profiles and clinical correlations remain underexplored. Methods: This study analyzed gut microbiota in 45 children aged 2–18 years diagnosed with ASD. Stool samples underwent 16S rRNA gene sequencing. Clinical assessments included ASD diagnostic subtype, adaptive functioning using the Vineland Adaptive Behavior Scale, gastrointestinal symptoms as per the Rome IV criteria, dietary patterns, and demographic variables. Statistical analyses correlated microbiota profiles with clinical features. Results: Gut microbiota composition was significantly influenced by delivery mode, age, sex, and diet. Vaginally delivered children had higher beneficial SCFA-producing bacteria, whereas Cesarean section was linked to increased pathogenic Clostridiales. High-calorie and protein-rich diets correlated with shifts toward pro-inflammatory taxa. Microbial diversity and specific genera correlated with adaptive behavior domains (communication, socialization, motor skills) and severity of gastrointestinal symptoms. Both pro-inflammatory and anti-inflammatory bacteria variably impacted neurodevelopmental outcomes. Conclusions: Gut microbiota composition in children with ASD is shaped by multifactorial influences and connected to neurobehavioral and gastrointestinal phenotypes. The findings of this study support the potential of microbiota-targeted interventions to ameliorate ASD-associated symptoms and improve quality of life.