The microbiome link to autism disorders

• ‘Fix your gut, fix your brain’ an underrated idea, is gaining relevance today as more and more research throws light on the role of the community of bacteria living in your gut, that is, the gut microbiome.
• A healthy gut microbiome is not a panacea but it may be able to help improve the quality of life of individuals with various diseases that lack other proven interventions.
• Differences in gut microbiome composition have been implicated in several diseases, including Crohn’s disease, celiac disease and particularly, autism.

Autism spectrum disorder (ASD)

• It is the term for a group of neurodevelopmental disorders.
• Researchers are yet to fully understand the aetiology of ASD.
  • Aetiology is the study of factors that cause a condition or disease.
• However, they are beginning to find that a disorder in the gut-brain axis could have a prominent role.

What Data say?

• According to the WHO, ASD affects one in 100 children.
• Children with ASD have impaired social interactions, lack verbal and nonverbal communication skills, and display restricted and repetitive behaviours.
• There are gastrointestinal problems associated with a subset of children with ASD.
• Limited research findings as well as anecdotal evidence indicate the presence of various gastrointestinal problems, like constipation, diarrhoea, flatulence, and bloating, among others, in children with ASD.
• Researchers have proposed several theories to explain the aetiology of ASD, the pathophysiology of the disorder remains largely unknown.
  • Pathophysiology is the study of a condition’s impact on biological processes.

Studying the link

• Profound exploration of the human microbiome by researchers, is dramatically reshaping our understanding of the connections between human health, diseases, and microbiomes.
• The gut microbiome is believed to have a big impact on immune modulation and metabolic activities in the human body.
  • Immune modulation refers to the efforts of the immune system to ensure its response is proportionate to a threat.
• Investigations of the dynamic cross-talk between the gut microbiome and the host environment have revealed potential connections to ASD symptoms.
• Aberrant antigen trafficking through an impaired intestinal barrier could allow these antigens to eventually pass through the barrier surrounding the brain, triggering a chain of events that worsen ASD symptoms.

Ongoing research

• Reserchers have explored the gut microbiome in children with and without ASD, and have reported several interesting microbial biomarkers in children with ASD.
• Dysbiosis — an imbalance — in the gut microbiome of children with ASD can be observed.
• They had a higher abundance of lactobacillaceae, bifidobacteriaceae, and veillonellaceae bacteria.
• The fraction of bacteria of the phylum firmicutes was found to be significantly higher in the guts of children with ASD.
• Certain microbes that produce short-chain fatty acids (SCFA), such as faecalibacterium and roseburia are also found in children with ASD.
• This supports the hypothesis that a lower level of SCFAs in ASD could lead to an imbalance in brain function and behaviour.

What can you do?

• Reinstating a balance in the gut microbiome and reversing gut dysbiosis among children with ASD could alleviate many problems they face and improve their quality of life.
• One promising approach to reverse gut dysbiosis is faecal microbial transplantation (FMT), where stool samples from healthy individuals are transplanted into the large intestines of affected children.
• There is also some evidence that gluten-free and casein-free diets can help children with ASD.
• This could be because some of these children have been found to lack the bacteria that helps break down casein and gluten into metabolites.
• In all, the role of diet, prebiotics, probiotics, synbiotics (which combine the benefits of probiotics and prebiotics), and FMT for the efficient management of ASD can be said to be encouraging.