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You have probably heard bits and pieces of this story: individuals with autism are more likely to suffer from gastrointestinal issues than those without; leaky gut and an altered microbiome are common in those on the spectrum; and broadly, there is a gut-brain connection.

What does it all mean, and how does it fit together? To truly understand the concept of the gut-brain connection, it’s important to focus on that word: connection. The research on specific components of this topic is extensive, and impossible to cover in a blog post. Instead, here we give an overview of how it’s all connected- the gut, the brain, the immune system, inflammation- and how they’re tied together in autism.

Research has found that up to 90% of individuals with Autism Spectrum Disorder experience some form of chronic gastrointestinal upset (1): constipation, diarrhea, bloating, abdominal pain, Irritable Bowel Syndrome. Further research has gone deeper to link this prevalence to a high incidence of “leaky gut” in those with autism (2), as well as significant differences in their microbiota (the vast collection of microbes that we house in our gut) compared to healthy individuals (3).

What is Leaky Gut?

Leaky gut is the term given to increased intestinal permeability: the spaces between the cells of the gut wall become larger than they should be, allowing substances to “leak” out of the gut and into the bloodstream.

These substances can include toxins, bacteria, viruses, pathogens, and overgrowth of yeast (which, needless to say, are all substances we do not want leaking out into our bloodstream) as well as undigested food particles.

When food particles that haven’t been completely digested leak into the bloodstream, our bodies interpret them as foreign intruders, and launch into an inflammatory immune response designed to protect us.

This inflammatory reaction can easily lead to food allergies or sensitivities: if our immune system has reacted to the presence of intrusive food particles by creating antibodies that fight them, it will remember this, and will unleash the same inflammatory defense mechanisms the next time it encounters the same substance.

This chronic inflammation comes with a number of consequences, not the least of which is the depletion of antibodies that protect the intestinal tract from harmful bacteria and fungi that can worsen leaky gut, thus creating, of course, a vicious cycle.

And inflammation, when it reaches the brain, can cause behavioural issues, difficulty concentrating, cognitive and language delays, and sleep disturbances.

This interaction is no small piece of the puzzle. Not only do we see an increased prevalence in gastrointestinal issues/digestive problems in individuals with autism, but we also see an increased prevalence in inflammation and immune dysregulation (4).

Common Symptoms:

-Gastrointestinal symptoms: chronic diarrhea, constipation, or both; IBS; abdominal discomfort; bloating; nausea

-Food intolerances, allergies, and sensitivities

-Environmental allergies; asthma

-Intestinal pathogens: yeast, candida, viruses, bacteria, parasites

-Behavioural issues

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