Two new studies strengthen the gut-brain connection in autism

Two fascinating new studies are shedding light on the association between the gut, the brain, and autism. The new research reveals how gastrointestinal problems can be triggered by the same gene mutations associated with autism, and a striking mouse study has demonstrated how a fecal transplant from humans with autism can promote autism-like behaviors in the animals.

One of the more intriguing areas of microbiome research is the growing connection between gut bacteria and autism. Several recent, albeit small, studies have revealed behavioral and psychological symptoms of autism in children can be improved using fecal transplants from healthy subjects. Exactly how the microbiome could be influencing autism symptoms is still unclear but one new study, led by researchers from Caltech, has strengthened this intriguing gut-brain hypothesis.

The research began by taking microbiome samples from human subjects, both with and without autism, which were then transplanted into germ-free mice.

The results were striking, with the animals receiving gut bacteria from human subjects with autism displaying hallmark autistic behaviors such as decreased social interactions and increased repetitive behaviors. The mice administered with gut bacteria from non-autistic human donors did not display these behavioral symptoms.

While affirming surprise at how profound the behavioral effects were in the mice receiving the microbiome transplants from autistic subjects, Gil Sharon, first author on the new study, is quick to note that this research does not imply gut bacteria explicitly causes autism. Instead the research suggests the microbiome more likely interacts with a variety of other factors to potentially enhance the severity of autistic symptoms in an individual subject.

“Our study shows that the gut microbiota is sufficient to promote autism-like behaviors in mice,” says Sharon. “However, these findings do not indicate that the gut microbes cause autism.”