Gut bacteria have been found contributing to autism disorder symptoms, according to new research that sheds new light on potential causes of the condition.
The study focused on mice, but if it's proven in humans, these new insights could pave the way for treatments for ASD that address the gut instead of the brain, such as probiotics.
Gut Bacteria And Autism Symptoms
In a paper published in the journal Cell, researchers from the California Institute of Technology supports the theory that there is a link between gut bacteria and autism.
Sarkis Mazmanian, study author and Caltech's Luis B. and Nelly Soux Professor of Microbiology, explained in a news release that previous studies have found differences between the gut bacteria of individuals with ASD and those without. However, scientists haven't been able to determine if the changes in the microbiome are an effect of having ASD or if it's the other way around and these changes contribute to ASD symptoms.
The new study shows that gut bacteria could promote autism-like symptoms in mice.
"However, these findings do not indicate that the gut microbes cause autism," stressed study author Gil Sharon, adding that further research is needed to address the effects of gut bacteria in humans.
The Experiment With Mice Models
For their research, the authors used mice that have not been exposed to microorganisms. A group of these "germ-free" mice were given gut microorganisms from children with autism via fecal transplant, while another group were transplanted gut microorganisms from individuals without autism.
Findings showed that mice given microbiota from people with ASD displayed autism-like symptoms, including spending less time interacting with other mice, vocalizing less, and demonstrating repetitive behavior. The mice who were given microbiota from people without ASD did not display the same symptoms.
Aside from the changes in their behavior, mice with the microbiota from people with ASD had altered gene expressions in their brains as well as lower amounts of two metabolites also associated with ASD symptoms known as 5AV and taurine.
The team attempted to treat the mice with 5AV and taurine, which caused a decrease in autism-like behaviors.
Mazmanian and his team acknowledged that plenty of factors make autism more complicated in humans than mice, but their research provides valuable clues on how the gut bacteria influences neural changes associated with ASD.
"It suggests that ASD symptoms may one day be remedied with bacterial metabolites or a probiotic drug," pointed out Mazmanian. "Further, it opens the possibility that ASD, and perhaps other classical neurologic conditions, may be treated by therapies that target the gut rather than the brain, a seemingly more tractable approach."