Association Among Gut Microbes, Intestinal Physiology, and Autism

Autism spectrum disorder (ASD) is a set of neurodevelopmental disorders characterized by two core symptoms: social deficits and increase in stereotypic/repetitive behaviors. Along with the core symptoms of ASD, other comorbid conditions can be observed in certain populations of people with ASD, such as gastrointestinal (GI) complications and altered gut microbiome (Adams et al., 2011 ; Parracho et al., 2005). Homeostasis of the GI system is closely regulated by the gut microbiota. Therefore, whether the gut microbiota is a contributing factor for ASD has been postulated recently. Several key questions have been raised. Do gut microbes contribute to the behavioral symptoms in ASD? How do gut microbes affect behavioral output through the gut–brain axis? How do gut and brain communicate with each other? Due to the complexity of the distal connection between gut and brain, these are the key questions that remain unanswered in the field.