Autism and gut bacteria

According to the CDC, about one in every 59 children in the U.S. is diagnosed with autism, up from one in every 150 in 2000. Alarming numbers! No one really knows why the numbers are escalating in this way. (It’s not from vaccinations!) Among other things, researchers have found that 30-50% of all people with autism suffer from gastrointestinal problems, such as diarrhea or constipation. They have also found that children with autism have lower diversity of microbiota in their intestines as well as a nearly-depleted strains of helpful bacteria.

For years, scientists have been looking at the ways in which gut bacteria affect brain communication and neurological health. In the words of one, “We are finding a very strong connection between the microbes that live in our intestines and signals that travel to the brain.” To test the relationship between the gut microbiome and autism, 18 children were given fecal transplants to alter the makeup of their gut microbiome. The transplant regimen (Microbiota Transfer Therapy) was rather rigorous: first, pre-treatment with an antibiotic to kill existing intestinal bacteria followed by a bowel cleanse, a stomach acid suppressant, and finally fecal microbiota transfer every day for seven to eight weeks.

Amazingly, this treatment reduced autism symptoms, such as social communication difficulties and repetitive behaviors, by 45%, and the effects seem to be lasting. At the start of the trial, 83% of the participants were rated as “severe” autism. At the end, only 17% were severe, 39% were mild/moderate; and 44% were below the cut-off for mild autism.

Interestingly, many of the participants share common history, including birth by C-section, reduced breastfeeding, increased antibiotics, and low fiber intake by both mother and child—conditions that lead to limited biodiversity in gut bacteria.

Much remains to be done, including understanding which microbes and chemicals produced by the microbes are driving the behavioral changes in autistic children. It can’t happen soon enough. 

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