Understanding the Brain-Gut Axis: Its Role In Autism

Is your stomach your second brain?

Let’s find out -

Up to 70% of children with ASD have impaired gastrointestinal function (Gondalia, 2012)!

Here’s what that means in simple words -

Recent research on the microbiota-gut-brain axis indicates a direct connection between the brain and the gut. This hints at how the gut microbiota can influence several neurological conditions, including autism.

Many autistic individuals experience gastrointestinal symptoms.
Early microbial colonisation, mode of delivery, and use of antibiotics play a major role in altering the gut microbiome, which may relate to autism’s early onset.

Understanding the microbiota: Gut-brain axis

Recent research on the gut-brain axis suggests that the gut is almost like a “second brain.” It contains millions of nerve cells that form an extensive network called the enteric nervous system (ENS). The vagus nerve connects the ENS with the central nervous system (CNS), forming the gut-brain axis, or what some call the body’s 'second brain.

Simply put, emotions and actions are influenced not only by your brain but also by your gut. The gut which is responsible for a lot of nervous system activity that we usually attribute entirely to the brain.

Simply put, emotions and actions are influenced not only by your brain but also by your gut. The gut which is responsible for a lot of nervous system activity that we usually attribute entirely to the brain.

90% of neurotransmitters, including serotonin, are produced in the gut. They play a huge role in influencing our emotions by regulating the gut-brain axis. Understanding this Microbiota-Gut-Brain Axis is key in autism spectrum disorder treatment. 

The effects of early microbial colonisation on autism

Microbial colonisation is when microorganisms attach to the surface and multiply. This refers to bacteria on our body’s surfaces or in our gut, which does not necessarily cause disease.

There is ample evidence to show that microbial colonisation in this gut starts during prenatal development inside the mother’s womb. It takes place in the placenta and the amniotic fluid. Colonisation of some bacterial species can be passed on to the infant through the breast milk of lactating mothers. Pioneer microbial colonisation starts in the GI tract of pre-term infants right after birth. After a year, during which a complex microbiota develops, its composition stabilises by around two or three years of age. 

The brains of neonates also grow from 36% to approximately 90% of their future adult volume until age 2. Establishing a healthy microbial composition in infants is vital during this critical period of brain development, as studies suggest a connection between gut health and behavioural symptoms.

Effect of Antibiotics on ASD

A human’s microbiome develops from birth until the age of 3. Using antibiotics during these formative years can influence the development of metabolic and neurological conditions. Antibiotics can seriously impact the gut’s microbial composition by disrupting the growth of pathological microbes. Early and excessive use of antibiotics can lead to microbial dysbiosis, which may play a role in the development of autism.

This affects the gut-brain axis. It can lead to epigenetic changes, potentially influencing the development of Autism Spectrum Disorder.. A recent study showed that autism behavioural symptoms and gut health are most definitely linked. 

A 2018 study by Eshraghi found that 34.5% of autistic children had been exposed to extensive and repeated use of broad-spectrum antibiotics. It was more than six courses compared to a control group with more than six courses.

Significance of microbial therapeutics for Autism Spectrum Disorder treatment

Clinicians working with children are increasingly assuming a link between ASD and gut dysfunction.

A better understanding of the gut-brain axis and the roles of gut bacteria may lead to a breakthrough in autism spectrum disorder treatment. In nutritional approaches for autism, doctors often recommend a plant-based diet, prebiotics, and probiotics.

Prebiotics are non-digestible food ingredients that support the growth of beneficial bacteria in the gut. In 2019, the US Food and Drug Administration, recognised Microbial Transplant Therapy (MTT) as a potential approach to managing ASD. Although the FDA has recognized microbial transplants for severe conditions like Clostridium difficile infections, it has not specifically approved MTT for autism. However, ongoing research is exploring its potential benefits in managing ASD symptoms by restoring gut microbial balance, with preliminary studies showing promising outcomes.

Microbial Transplant Therapy involves a series of steps:

• Taking antibiotics for two weeks.
• A bowel cleanse- Flushing out the large intestine with liquids such as water.
• Receiving faecal microbiota transplant- A procedure that delivers healthy human donor stool to a child via enema or a capsule. 
• Taking daily maintenance doses for seven to ten days.

Ongoing research explores MTT's full potential as an approach to managing autism spectrum disorder.

Conclusion

Exploring the underlying molecular mechanism of the gut microbiome in the pathogenesis and advancement of ASD and discovering promising therapeutic agents could bring new hope for the management of ASD in the near future.

At IAC, we have a qualified team of some of the best clinicians and nutritionists who are devoted to finding the right nutritional therapy for autism and optimising the gut health of each individual we are privileged to support.