Research progress on the microbiota-gut-brain axis in autism spectrum disorder: a narrative review.

Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders characterized by deficits in social interaction and the presence of repetitive, stereotyped behaviors, often accompanied by gastrointestinal symptoms. The prevalence of ASD is on the rise, and the lack of specific pharmacological treatments places a significant burden on families and society. However, the discovery of the microbiota-gut-brain axis (MGBA) offers new opportunities for research into ASD. The gut microbiota, a core component of the MGBA, engages in bidirectional communication with the central nervous system through neural, immune, and metabolic pathways. Dysregulation of the gut microbiota is closely associated with the pathogenesis and progression of ASD. Children with ASD often exhibit specific alterations in their gut microbiota, including an increased abundance of Firmicutes and Proteobacteria, a decreased abundance of Bacteroidaceae, and abnormalities in short-chain fatty acid metabolism. These alterations are associated with neurotransmitter imbalances and impaired intestinal barrier function, which are thought to subsequently contribute to neuroinflammation. Given these insights, intervention strategies targeting the gut microbiota-such as probiotics/prebiotics supplementation, fecal microbiota transplantation (FMT), and gluten-free/casein-free diets-show promise in alleviating gastrointestinal symptoms and core behavioral deficits in children with ASD. This narrative review synthesizes the fundamentals of the MGBA, critically examines the mechanisms linking gut microbiota to ASD, discusses recent advances in related treatments and their methodological limitations, and aims to provide insights for future research and the potential development of precise, microbiota-based interventions for ASD.