Children with autism may benefit from fecal transplants a new study has found.

Behavioral symptoms of autism and gastrointestinal distress often go hand–in–hand, and both improved when a small group of children with the disorder underwent fecal transplant and subsequent treatment.

In the study of 18 children with autism and moderate to severe gastrointestinal problems, parents and doctors said they saw positive changes that lasted at least eight weeks after the treatment. Children without autism were included for comparison of bacterial and viral gut composition prior to the study.

The study, which appeared in the journal Microbiome, was conducted while Gregory and her adviser and co–author, Matthew Sullivan, were at the University of Arizona. Other lead researchers on the project are from Arizona State University and Northern Arizona University.

A growing body of research is drawing connections between the bacteria and viruses that inhabit the gut and problems in the brain, and it is possible the two are tied together in an important way in autism, she said.

Previous research has established that children with autism typically have fewer types of some important bacteria in their guts and less bacterial diversity overall – a difference that held true in this study. That could be because many of them are prescribed a lot of antibiotics in the first three years of life, the research team wrote in the study.

Parents of the children not only reported a decrease in gut woes including diarrhea and stomach pain in the eight weeks following the end of treatment: They also said they saw significant changes for the better when it came to behavioral autism symptoms in their sons and daughters, who ranged from 7 to 16 years old.

The researchers collected this information from parents through established, standardized questionnaires to assess social skills, irritability, hyperactivity, communication and other measures. One of those tools showed the average developmental age increased by 1.4 years after treatment.

The average score on a scale for ranking gastrointestinal symptoms dropped 82 percent from the beginning to the end of treatment. And when the researchers asked parents to give feedback on 17 autism–related symptoms, they saw overall improvement that was sustained two months after the final treatment.

Doctor–reported symptoms (from the Childhood Autism Rating Scale) decreased by 22 percent at the end of treatment and 24 percent eight weeks after treatment ended compared with ratings at the start of the study.

Researchers also were able to document a rebalancing of the gut following treatment. At the end of the study, the bacterial diversity in the children with autism was indistinguishable from their healthy peers. The study also included a unique viral analysis by Ohio State scientists, made possible because of previous work in the world’s oceans.

Gregory, who is particularly interested in the interplay between viruses and bacteria, used genetic testing to examine the viral diversity in the guts of the treated children. It rebounded quickly, and became more similar to the donor’s microbiome.

“Those donor viruses seemed to help,” she said.

In this study, the researchers used a method called microbiota transfer therapy, which started with the children receiving a two–week course of antibiotics to wipe out much of their existing gut flora. Then, doctors gave them an initial high–dose fecal transplant in liquid form. In the seven to eight weeks that followed, the children drank smoothies blended with a lower–dose powder.

James Adams, one of the study’s lead authors and an Arizona State University professor who specializes in autism, called the results compelling, but cautioned that larger, more rigorous studies confirming benefits must be done before the approach