The Gut-Brain Connection to Autism

Research supports the idea of a gut-brain connection to autism. In fact, the gut may be involved in many mental health issues. Here's what you should know.

Up to 90 percent of people with autism have gastrointestinal problems: bloating, abdominal pain, and alternating diarrhea and constipation. Researchers have found evidence of a common root for the gut trouble and symptoms of autism, or autism spectrum disorder (ASD).

In 2003, a landmark study of two brothers linked a particular mutation to ASD. The researchers also kept notes on the brothers’ gut problems.

The mutation they focused on interfered with a mechanism ― something like Velcro ― that keeps neurons in contact. The research shows that the same mutation also affects gut contractions, the number of neurons in the small intestine and how quickly food moves through it, and responses to a significant brain chemical.

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Another study found differences in the gut microbes of mice with the mutation, compared to mice without the mutation.

Scientists also know from separate research that children with ASD tend to have different gut microbes than other children.

The discoveries confirm the idea that researchers should study how ASD medications affect the gut, and exactly how the mutations associated with ASD change the microbes in the gut. It’s possible that altering the microbes directly could affect the symptoms of ASD. Treating gastrointestinal issues already can sometimes affect how children with ASD feel and behave.

The gut affects other mental health conditions as well — and the mechanism may be inflammation, an immune reaction.

One theory goes like this: If young children aren’t exposed to enough of the right kind of microorganisms they end up with too few regulatory T cells, which act as stop signs for other immune cells that produce inflammation. Without those T cells, the immune system is over-reactive. A child could end up with the tendency to produce inflammation in response to stress. Inflammation then leads to mental health symptoms.

As it happens, people with autism tend to be short on T-cells and in a state of unnecessary inflammation. It’s as if they had a constant low-grade infection. Separate research has linked levels of inflammatory cells to the severity of ASD symptoms.

The tendency for chronic inflammation may be passed from mother to child. There is evidence that pregnant women with high levels of C-reactive protein, a measure of inflammation, are much more likely to bear children with ASD. The same is true of mothers with autoimmune or inflammatory diseases like  rheumatoid arthritis, asthma, celiac disease, diabetes, and obesity.

Changes in diet often relieve gastrointestinal symptoms. Children with ASD tend to dislike fruits, vegetables, and slippery, soft foods. If your child is also taking Ritalin, the drug may cut his appetite, and he may be too distractible to finish his meals.

According to the Academy of Nutrition and Dietetics, there isn’t solid science to show that gluten or casein-free diets affect ASD symptoms, though the idea is floating around. Instead, you could try emphasizing routine mealtimes and letting your child have a favorite food at each meal or choose his favorite seat.

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