Jornal de Toxicologia Clínica
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Role of Gut-Brain Axis in the Aetiology of Neurodevelopmental Disorders with Reference to Autism

Afaf El-Ansary, Ghada H. Shaker and Maha Zaki Rizk

Neurodevelopmental disorders, especially in children, result in brain and nervous system damage. These may result from environmental contaminants, intrauterine environment, infectious diseases or exposure to nanoparticles that cross the blood brain barrier. Gut microbiota directly influence the immune system, nervous system and brain development during microbial colonisation of the newborn (microbiota gut-brain axis) and are controlled and modulated by different endogenous and exogenous factors. Of these factors feeding with human milk creates a healthy microbiota in the infant gut and reduces incidence and severity of infections and promotes normal gastrointestinal function. In addition there is a direct correlation between maternal vaginal and intestinal bacteria, gut microbiota composition, and increased rates of obesity, metabolic and neuropathological disorders such as autism. Gut-brain factors secondary to alterations in gut microbiome by antibiotics or diet may influence brain function in patients with Autism Spectral Disorders (ASD). Children with ASD ingest food products that provide high carbohydrates for bacterial fermentation to produce propionic acid through the bacterial strain Clostridium difficile, which is associated with diarrhoea. Treatment strategies to reduce Clostridium difficile include probiotics, prebiotics, faecal transplantation and hyperbaric oxygen therapy. Studies of microbiota-gut-brain axis could provide a deeper understanding of the relationship between the intestinal bacteria and their hosts which could help to suggest potential therapeutic strategies through affecting the composition of gut microbiota.