December 6, 2013 Leave a comment
How can I not write about new findings linking autism to the microbiome (at least in mice)? I can’t not. From Science:
Many physicians and parents report that their autistic children have unusually severe gastrointestinal problems, such as chronic constipation or diarrhea. These observations have led some researchers to speculate that an ailing gut contributes to the disorder in some cases, but scientific data has been lacking. Now, a provocative study claims that a probiotic treatment for gastrointestinal issues can reduce autismlike symptoms in mice and suggests that this treatment could work for humans, too.
The reported incidence of gut maladies in people with autism varies wildly between published studies—from zero to more than 80%—making it difficult to establish just how commonly the two conditions go together, says principal investigator Sarkis Mazmanian, a microbiologist at the California Institute of Technology (Caltech) in Pasadena. Overall, however, the evidence seems to point toward a connection. Last year, for example, a Centers for Disease Control and Prevention study of thousands of children with developmental disabilities found that kids with autism were twice as likely as children with other types of disorders to have frequent diarrhea or colitis, an inflammation of the large intestine…
“It’s really striking that any bacterial treatment—even a transient one—could have a lasting impact on behavior,” Hsiao says. The most interesting thing about the results, she says, was not the correction of the autistic symptoms in the mice, but the clues the study provided about how the gut’s microbial population may affect the brain and behavior. The researchers found that levels of a substance called 4-ethylphenylsulfate that is produced by gut bacteria increased 46-fold in the mice with autistic symptoms, but returned to normal after treatment withB. fragilis. When the team isolated that chemical and injected it into healthy mice, the rodents showed increased anxiety, another autismlike symptom, she says. Although the substance did not provoke the symptoms seen in the previous experiment, Hsiao says that the animals’ altered response suggests that the substance could play a role in the disorder. Hundreds of other metabolic byproducts also changed in quantity after B. fragilis was administered and could have an effect, she adds.
By demonstrating that a widely used mouse model of autism does have gastrointestinal problems, and that these problems are associated with behavioral symptoms, the new research “shows us something fabulous,” says Betty Diamond, an immunologist at the Feinstein Institute for Medical Research in Manhasset, New York. She cautions, however, that it would be premature to use B. fragilis or another probiotic as a treatment in humans. “We don’t really understand” which bacterial species are important or how they colonize the gut, she says.
Wow. Pretty amazing stuff. Of course, given the constant advances on what we’re learning about the impact of our microbiome, perhaps not all that surprising. I don’t think we’re looking at any potential “cure” for autism here– I suspect autism is far more complicated than simply one’s gut bacteria and how it interacts with the brain, but I suspect that there is very real potential for a probiotic treatment that would definitely lessen some of the negative symptoms of autism. And actually, my son Alex can be anxious as hell. Not that I’m going to drop the Risperdal any time soon (though, I sure wish we could because the appetite and weight gain are a really unfortunate side effect– I’m a little wistful when I see photos of thin Alex on my screen saver), but I’m definitely going to look more into the issue of bacteria and anxiety.
And, big picture… yet more evidence that understanding these bacteria-human relationships are going to be at the forefront of coming medical advances.