The Gut-Brain Axis in Autism Spectrum Disorder: Microbiota-Targeted Therapies and Neurobiological Insights

Introduction: Autism spectrum disorders (ASD) are complex neurodevelopmental disorders with an etiology that includes genetic, environmental, immunological, and neurobiological factors. Increasing evidence suggests that the gut-brain axis (GBA), a bidirectional communication system linking the gastrointestinal tract with the central nervous system, may play a key role in their pathogenesis. Research objectives: This review aimed to provide an overview of current insights into the relationship between gut microbiota and brain function in the context of ASD, with a specific focus on neuroimmunological, neuroendocrine, and metabolic pathways. Methods: The methodology involved an analysis of scientific literature focusing on studies published in the last 15 years, sourced from PubMed, Google Scholar, and Web of Science databases. The review included experimental, clinical, and review studies related to gut microbiota, dysbiosis, immune response, hypothalamic-pituitary-adrenal (HPA) axis activation, stress, and microbiota-targeted interventions. Key findings: Children with ASD exhibit characteristic alterations in microbiota composition, increased intestinal permeability, and chronic inflammation. Dysbiosis disrupts the metabolism of neurotransmitters (GABA, serotonin, dopamine), affecting brain function. A relationship has been identified between the microbiota and activation of the HPA axis as well as the stress response. Factors such as cesarean section delivery, antibiotic therapy, and feeding methods modify the microbiota in early life. Probiotic, prebiotic, and microbiota transplantation therapies may improve ASD symptoms. Conclusions: Modulation of the gut microbiota through probiotics, prebiotics, and Fecal Microbiota Transplantation (FMT) may support ASD treatment. However, further clinical research and ethical guidelines are necessary to ensure their safe application in children.