Autism is primarily a disorder of the brain, but research suggests that as many as nine out of 10 individuals with the condition also suffer from gastrointestinal problems such as inflammatory bowel disease and “leaky gut.” The latter condition occurs when the intestines become excessively permeable and leak their contents into the bloodstream. Scientists have long wondered whether the composition of bacteria in the intestines, known as the gut microbiome, might be abnormal in people with autism and drive some of these symptoms. Now a spate of new studies supports this notion and suggests that restoring proper microbial balance could alleviate some of the disorder's behavioral symptoms.
At the annual meeting of the American Society for Microbiology held in May in Boston, researchers at Arizona State University reported the results of an experiment in which they measured the levels of various microbial by-products in the feces of children with autism and compared them with those found in healthy children. The levels of 50 of these substances, they found, significantly differed between the two groups. And in a 2013 study published in PLOS ONE, Italian researchers reported that, compared with healthy kids, those with autism had altered levels of several intestinal bacterial species, including fewer Bifidobacterium, a group known to promote good intestinal health.