Gut-brain Axis and its Influence in Autism Spectrum Disorder

Abstract

Emerging evidence suggests that the gut microbiota and the brain are interconnected through a bidirectional communication via the microbiome-gut-brain axis. The development of the microbiota and nervous system occurs at the same time, being childhood and adolescence the most critical periods for their maturation. Disruptions in these developmental processes heighten the vulnerability to neurodevelopmental disorders, including autism spectrum disorder (ASD). Gut microbiota refers to a community of microorganisms that colonize the gastrointestinal tract where factors like delivery route, method of feeding, gestational age, host genotype, antibiotic usage and others influence its development. Dysbiosis of the gut microbiota, resulting in a proinflammatory state, can precipitate a spectrum of diseases ranging from gastrointestinal to psychiatric and neurological disorders. The exact mechanisms by which gut and brain communicate are not fully elucidated. Vagus nerve, enteric nervous system, hypothalamus-pituitary-adrenal axis, immune system, neurotransmitters and intestinal microbial metabolites are thought to be the manly routes through which these systems communicate. In this review we explore the development of the gut microbiota and the communication routes of the microbiome-gut-brain axis and how its disruption can influence the onset and symptoms of autism spectrum disorder. We conclude with an overview of potential new therapeutic strategies targeting the gut microbiota such as probiotics, prebiotics and fecal microbiota transplantation and how they can treat and alleviate some typical symptoms of autism spectrum disorder.