THE GUT MICROBIOTA AND THE BRAIN: RELATIONSHIP AND BIDIRECTIONAL COMMUNICATION IN AUTISM SPECTRUM DISORDERS

Growing evidence suggests that the gut microbiota-brain axis plays a crucial role in the development and function of the immune, metabolic and nervous systems. The diversity of the bacterial populations, as well as the metabolites and molecules they produce, have proven to be influential on the function of many different organs, remarkably affecting human health. Notably, the composition and the activity of the gut microbiota is significantly different between healthy and sick people with regards to several different neurological disorders, including Autism Spectrum Disorders (ASD). Despite the already well-known genetic causes, also environmental factors seem to be considerably influential in determining ASD symptoms. As a matter of fact, the gut microbiota seems to play a critical role in both gastrointestinal (GI) and behavioural abnormalities affecting ASD patients. Although the specific mechanisms and pathways underlying the gut-brain axis communication in ASD still remain unclear, this topic is gaining increasing interest, as new therapeutic approaches to treat ASD symptoms may be discovered. By showing results of both pre-clinical and clinical cases, the aim of this thesis is to try to better understand the general relationship occurring between the gut microbiota and the brain, in order to show how the alterations of various aspects of this dynamical communication can consequently be relevant in the pathogenesis and symptoms of ASD individuals.