A new study from the University of Southern California (USC) has found that gut health could play a big role in shaping the brain and behavior of children with autism. The research, published in Nature Communications, suggests that imbalances in the digestive system may affect important brain chemicals and influence autism-related behaviors.
This discovery is part of a growing area of research looking at how the gut and brain are deeply connected, often referred to as the “gut-brain axis.”
The research team collected data from 84 children between the ages of 8 and 17, including 43 children diagnosed with autism and 41 neurotypical children (those without autism).
They studied their behavior, took brain scans, and collected stool samples to examine the children’s gut bacteria. These bacteria help break down food and produce chemicals called metabolites, which play key roles in the body and brain.
The researchers found that certain metabolites in the gut were different in children with autism compared to neurotypical children. One of the main discoveries involved a chemical process called the “tryptophan pathway.”
Tryptophan is a nutrient found in many foods, and it helps the body produce serotonin—one of the brain’s most important chemicals for emotions, learning, and social interaction.
Serotonin is best known for its role in mood and emotional health. It helps people feel calm, focused, and socially connected. Most people don’t realize that about 90% of the body’s serotonin is actually made in the gut, not the brain. That means if something is wrong in the gut, it can affect how much serotonin is produced—and that might have an impact on the brain.
The lead researcher, Professor Lisa Aziz-Zadeh from USC’s Brain and Creativity Institute, explained that this study connects three areas: the gut, the brain, and behavior. She said that many children with autism have different brain activity patterns, along with digestive problems like constipation and stomach pain.
These differences might be more than just separate symptoms—they could be connected through the gut-brain pathway.
From an evolutionary point of view, the gut may have been our “first brain.” The gut contains more nerve cells (neurons) than the spinal cord, and it sends about 90% of the communication signals to the brain—while the brain sends only 10% back.
This might explain why we often use phrases like “gut feeling” or “gut instinct.” Our emotions and body sensations are closely tied to the gut in ways we are just beginning to understand.
Aziz-Zadeh noted that many previous studies have looked at brain differences or gut bacteria in people with autism, but this study connects those dots. By looking at how gut bacteria and the chemicals they produce are related to brain function and behavior, researchers are getting a fuller picture of how autism works in the body.
Sofronia Ringold, a doctoral student who worked on the study, said she hopes these findings lead to new ways to support children with autism. For example, if future treatments could improve gut health, they might also improve brain function and reduce some of the behavioral challenges and physical discomfort that many children with autism experience.
In summary, this study adds strong evidence to the idea that the gut and brain are closely linked, especially in autism. Children with autism often face both digestive and social difficulties.
The research suggests that problems in the gut may lead to chemical changes that affect how the brain works—particularly in areas that manage emotions, learning, and social behavior.
The findings open up a hopeful path for future treatment. Instead of focusing only on the brain, doctors and scientists might also look at ways to improve gut health to help ease autism symptoms.
These could include changes in diet, probiotics, or other therapies designed to balance gut bacteria and boost serotonin levels. While more research is needed, this study points to a promising new direction—one that could make life easier and more comfortable for children with autism and their families.
If you care about autism, please read studies about a new cause of autism, and cats may help decrease anxiety for kids with autism.
For more information about health, please see recent studies about vitamin D that may hold the clue to more autism, and results showing strange eating habits may signal autism.
The research findings can be found in Nature Communications.
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