Your Child's Gut and Brain: What Autism Family Should Know

Could the key to improving your child's behaviour and communication be living in their gut?

It sounds surprising, but a growing body of scientific evidence, and more than 20 years of clinical experience working with over 2,000 children with Autism Spectrum Disorder (ASD) suggests the answer may well be yes.

What is the Microbiome?

The human body is made up of roughly 30 trillion human cells. But living alongside those cells are trillions upon trillions of microbes: tiny bacteria and viruses that inhabit our skin, gut, urinary tract, and respiratory system. Together, they form what we call the microbiome, and the vast majority of them live in our gut.

Think of the microbiome as an entire ecosystem living inside you, one that, when healthy, exists in perfect harmony with your body. In fact, you have more microbial cells living inside you than you have human cells in your entire body.

The Gut-Brain Connection

Scientists have known for years that the gut and the brain are intimately connected, primarily through a structure called the vagus nerve. This bidirectional communication pathway, now widely referred to as the "microbiota-gut-brain axis," allows the gut microbiome to directly influence brain function, behaviour, and mood.

Research published in Nature Neuroscience has identified autism-associated molecular and microbial profiles along this gut-brain axis. Separately, USC scientists have demonstrated that gut metabolites impact the brain, and the brain in turn affects behaviour, with the gut microbiome playing a central role in the production of serotonin, a neurotransmitter crucial for emotional processing and social interaction.

One statistic stands out above all others: gastrointestinal problems are four times more common in children with autism than in neurotypical children. This is not a coincidence. It is a biological signal that demands our attention.

What Goes Wrong?

When the microbiome becomes disordered, a state known as dysbiosis, it can have a profoundly detrimental effect on the brain. Studies have consistently shown that children with ASD have lower microbial diversity in their guts, with reduced levels of beneficial bacteria such as Bifidobacteria and Prevotella.

Several modern environmental factors can trigger this disruption:

Antibiotics: even a single course can dramatically alter the microbiome's diversity and complexity
Diet: a poor diet starves beneficial bacteria of the fibre they need to thrive
Mode of delivery and early colonisation: these play a significant role in establishing a healthy microbiome from birth

How Can We Test and Treat It?

The good news is that modern functional medicine has sophisticated tools to assess and address these imbalances.

Using PCR technology, which identifies bacteria and viruses by their DNA, we can now map the microbiome with remarkable precision. There is even a test developed at the Chinese University of Hong Kong that can suggest a diagnosis of autism with 80% accuracy using a stool sample alone. We also use a highly detailed tool called the GI Map, with over 100 million data points, to identify specific imbalances so they can be precisely corrected.

Treatment options include:

Prebiotics: dietary fibres that feed beneficial gut bacteria
Probiotics: live beneficial bacteria shown in randomised trials to improve social and behavioural scores in children with ASD
Dietary intervention: a healthy, varied, plant-rich diet is foundational to a healthy microbiome
Faecal Microbiota Transplant (FMT): transferring the microbiome from a healthy donor to the patient

The Evidence on Faecal Microbiota Transplant

FMT may be the most powerful tool in this space. An Arizona State University study led by Professor James Adams found that microbiota transfer therapy produced a nearly 50% reduction in ASD symptom severity, and crucially, those benefits continued to improve over the two years following treatment. At the start of that study, 83% of participants were rated as "severe" autism. Two years after treatment, only 17% remained in the severe category.

A systematic review confirmed that FMT produced significant improvements in gastrointestinal symptoms and core ASD behaviours, including social interaction and communication.

In China, a large-scale study at Shanghai Tenth People's Hospital found that approximately 60% of autistic children with gastrointestinal symptoms showed significant improvement in sleep, bowel function, behaviour and language following FMT. One 13-year-old boy in that study, who had been largely non-verbal, wrote and sent a card to his doctor after completing his fourth treatment course.

The Bigger Picture

Addressing the microbiome does not replace behavioural therapies like Applied Behaviour Analysis (ABA), occupational therapy, or speech therapy. Think of it this way: those therapies are the software, the programmes that teach skills and build communication. Treating the microbiome is about fixing the hardware, the biological foundation that everything else depends on.

When the hardware is working better, the software works better too.

By testing the microbiome and using targeted therapies to heal the gut, we can rebuild that biological foundation, alleviating physical symptoms and directly improving the behaviour and communication that every family is hoping to see.

Dr Tim Trodd

Family Medicine, Functional Medicine, General Practice

MBBS (London)
DCH (London)
DRCOG (UK)
MRCGP (UK)
FHKAM (Family Medicine)

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References

Morton, J.T., Jin, D.M., Mills, R.H., Shao, Y., Rahman, G., McDonald, D., Zhu, Q., Balaban, M., Jiang, Y., Cantrell, K., Gonzalez, A., Carmel, J., Frankiensztajn, L.M., Martin-Brevet, S., Berding, K., Needham, B.D., Zurita, M.F., David, M., Averina, O.V., Kovtun, A.S., Noto, A., Mussap, M., Wang, M., Frank, D.N., Li, E., Zhou, W., Fanos, V., Danilenko, V.N., Wall, D.P., Baldeón, M.E., Jacquemont, S., Koren, O., Elliott, E., Xavier, R.J., Mazmanian, S.K., Knight, R., Gilbert, J.A., Donovan, S.M., Lawley, T.D., Carpenter, B., Bonneau, R. and Taroncher-Oldenburg, G. (2023). 'Multi-level analysis of the gut-brain axis shows autism spectrum disorder-associated molecular and microbial profiles.' Nature Neuroscience, 26(7), pp. 1208 to 1217. Available at: https://doi.org/10.1038/s41593-023-01361-0.
Zhang, J., Zhu, G., Wan, L., Liang, Y., Liu, X., Yan, H., Zhang, B. and Yang, G. (2023). 'Effect of fecal microbiota transplantation in children with autism spectrum disorder: a systematic review.' Frontiers in Psychiatry, 14, p. 1123658. Available at: https://doi.org/10.3389/fpsyt.2023.1123658.