HOUSTON, Texas — Could a healthy cup of yogurt hold the key to undoing the behavioral impairments common in autism? A new study finds gut bacteria may help to ease the symptoms of the developmental disorder.
A team from Baylor College of Medicine says experiments on mice reveal symptoms of autism improved after they were fed the probiotic microbe Lactobacillus reuteri. Along with living in the gastrointestinal tract of humans, the healthy bacteria can also be an ingredient in probiotic yogurt. Researchers say mice taking L. reuteri displayed boosts in their social interactions. Scientists are now testing how this “good” bacteria works with autistic children in Italy.
“Despite all the scientific advances and the promise of gene manipulation, it is still difficult to modulate human genes to treat diseases, but modulating our microbiome may be an interesting, noninvasive alternative,” study co-author Professor Mauro Costa-Mattioli says in a university release.
“In my wildest dreams, I could have never imagined that microbes in the gut could modulate behavior and brain function,” Prof. Costa-Mattioli adds. “To think now that microbial-based strategies may be a viable way to treat neurological dysfunction, is still wild, but very exciting.”
The Houston team discovered that hyperactivity in mice with neurodevelopmental disorders is controlled by the host’s genes, with social problems influenced by gut bacteria. Effective therapies would likely need to be directed at both the brain and the gut microbiome to fully address all symptoms, the researchers suspect.
Treating disease through the gut
Other complex conditions such as cancer and diabetes may also have a gut bacteria component. The study, published in the journal Cell, experimented with mice genetically programmed to develop rodent versions of autism spectrum disorders because they lack both copies of the Cntnap2 gene.
“These mice presented with social deficits and hyperactivity, similar to those observed in autism spectrum disorders (ASD),” first author Sean Dooling, a PhD candidate in the Costa-Mattioli lab explains. “In addition, these mice, like many people with ASD, also had changes in the bacteria that make up their microbiome compared to the mice without the genetic change.”
Modulating the gut balance improved the social behavior in the mutant mice, but did not alter their hyperactivity. Autistic people have trouble with social, emotional, and communication skills that usually develop before the age of three and last for life.
“We were able to separate the contribution of the microbiome and that of the animal’s genetic mutation on the behavioral changes,” Dooling says. “This shows that the gut microbiome shouldn’t be ignored as an important variable in studying health and disease.”
“We found that L. reuteri also can restore normal social behavior but cannot correct the hyperactivity in Cntnap2–/– mice,” co-first author Dr. Shelly Buffington from the University of Texas Medical Branch in Galveston adds.
The bigger surprise came when the mice received a compound produced in the gut by L. reuteri. The metabolite also made them more sociable.
“This provides us with at least two possible ways to modulate the brain from the gut, with the bacteria or the bacteria-induced metabolite,” Dr. Buffington continues.
What makes some bacteria better than others?
Probiotics – tiny live organisms in yogurt and other fermented foods – can fight off “bad” bacteria. Previous studies have discovered connections between an unhealthy microbiome and neurological disorders ranging from Alzheimer’s to Parkinson’s to motor neuron disease.
“Our work strengthens an emerging concept of a new frontier for the development of safe and effective therapeutics that target the gut microbiome with selective probiotic strains of bacteria or bacteria-inspired pharmaceuticals,” Dr. Buffington explains.
It’s too early to use over-the-counter L. reuteri supplements to treat autism. Scientists are not certain which strains are effective or what dose to use at this time. However, the findings represent an important step forward as mental illnesses remain very difficult to treat.
“As we learn more about how these bacteria work, we will be able to more precisely and effectively leverage their power to help treat the brain and perhaps more,” Dooling concludes.
According to the Centers for Disease Control and Prevention, one in 54 children will have some form of autism spectrum disorder. ASD is over four times more common in boys than girls.
SWNS writer Mark Waghorn contributed to this report.