Reasoning through the Gut: The Microbiota-Gut-Brain Axis and its Role in the Pathogenesis of Autism Spectrum Disorder

Abstract

The age-old phrase ‘gut feeling’ is increasingly finding a scientific basis. The human gut houses a massive colony of microorganisms that not only maintain intestinal function, but also have far-reaching connections to the brain through a complicated ‘microbiota-gut-brain’ (MGB) axis. This axis has now been established to have implications in the management of various neuro-psychological conditions including Autism spectrum disorder (ASD), a condition that affects the way people communicate, behave and interact with others. Once considered a rare disorder, it is now estimated to have a prevalence of about 1 in 54 children in the United States. It is unfortunate that the existing cognitive-behavioral therapy protocols for ASD are prolonged and expensive, and that there is no currently approved medication for the core symptoms of the disorder. Scientists are now exploring the MGB axis for establishing possible therapeutic targets to alleviate the symptoms of ASD. This review attempts to highlight how the MGB axis works, and to capture the essence of the mechanisms that implicate the MGB axis in the pathogenesis of ASD. Further research in this direction may convincingly establish the role of novel treatment options for ASD ranging from probiotics and dietary modifications to newer modalities like fecal transplants, vagal nerve stimulation and gene therapy. Microbes, and not just behavioral intervention therapy, may hold the key to treating ASD.