We’ve recently learned that gut microbe therapy can be used to treat things like obesity and C. diff infection, but could it actually help with mental difficulties as well? A recent study showed that mice with autism-like traits found great relief in healthy human gut microbes, both from symptoms of autism and gastrointestinal difficulties associated with the disorder. The results come from lead author Elaine Hsiao from CalTech’s Division of Biology and Biological Engineering. The paper was published in the Dec. 5 edition of Cell.

Individuals with autism suffer from a variety of symptoms, the intensity of which is on a spectrum. Some of these symptoms can include delayed or absent social skills, behavior problems, language difficulties, and erratic or repetitive movements, among others. In the 1990s, one scientist suspected that autism was caused by vaccines, but that claim was based on fraudulent data and is not at all supported by the scientific community.

The research from CalTech builds off of their previous research that showed that the gut and autism could be connected, because so many people with the disorder have accompanying GI problems. For the most recent study, the team took a census of the gut microbes of wild type mice and compared it with those who exhibited autism-like symptoms, including anxiety, behavioral difficulties, and intestines that were "leaky" and compromised digestion. The mice with the behavioral disorder were shown to be lacking in Bacteroides fragilis when compared to the wild type. When researchers introduced that specific bacteria to the “autistic” mice through food, both behavioral problems and gastrointestinal difficulties diminished.

Additionally, the “autistic” mice were also shown to have levels of the compound 4-ethylphenylsulphate (4EPS) in their bloodstream that were 46 times higher when compared to the wild type. When 4EPS is injected into wild type mice, they begin to display symptoms of autism. While the researchers know that this compound is made by the gut, it is unclear if B. fragilis is responsible. 

To date, there have not been any large studies conducted about improving human brain function through the use of dietary probiotics. The results of this study could open the door to exploring that avenue. Because Autism Spectrum Disorders are just that, a spectrum; extensive research will need to be done to learn how to start bringing relief to those who need it. The team plans to continue their research by gaining a better understanding of how microbes in the gut are able to affect the brain.