Medical practice

More research needed to show if faecal transplants help autistic children

The Mail Online reports: “Autism symptoms can be reduced 50% in children who received faecal transplants.” But further research on a much larger group of people is needed to show if the treatment works.

Faecal transplants, originally designed to treat C.diff infections, involve receiving a transplant of gut microbes taken from a donor with healthy gut bacteria. This procedure has been found to improve gut health and digestive symptoms.

While autism is mainly associated with difficulty with communicating and interacting with others, autistic people can also experience digestive problems such as diarrhoea and constipation.

This small US study involved 18 autistic children. Researchers found an improvement in digestive symptoms and signs of autism 2 years after receiving a faecal transplant - 8 children no longer fitted the criteria for a diagnosis of autism and there was a 58% reduction in gut symptoms overall.

This is very early-stage research involving just a small sample of children.

The results of this study could also have been affected by the fact 12 of the children had changed their usual medication, supplements or diet during the course of the 2-year follow up. This means we cannot be certain that improvements in symptoms were down to the transplant.

Previous studies have shown an association between gut problems, such as constipation and diarrhoea, and autism but this is not the case for all autistic children. So even if this treatment is shown to be effective, it may just be for a select group of children.

Where did the story come from?

The study was carried out by researchers from Arizona State University, Integrative Developmental Pediatrics and Northern Arizona University, all in the US. It was funded by Finch Therapeutics and the Arizona Board of Regents.

The study was published in the peer-reviewed medical journal Scientific Reports on an open access basis so it can be read for free online.

The Mail Online reported the study accurately, included expert opinions and explained that a much bigger trial would be needed before the treatment could be approved.

What kind of research was this?

This was a follow-up study of a case series. This type of study takes a small group of people with a condition, gives them all the same treatment and follows them up over time. Any improvements or side effects might be due to the treatment, but a randomised controlled trial would be needed to verify the results.

What did the research involve?

The researchers followed up 18 autistic children who had previously been given a course of healthy donor gut bacteria. The children ranged in age from 7 to 17. Prior to the original study they had suffered from moderate to severe gastrointestinal problems such as abdominal pain, indigestion, diarrhoea and constipation since they were infants.

In the original study, the children were given:

  1. a 2 week course of vancomycin – an antibiotic to reduce unhealthy bacteria in the gut
  2. MoviPrep – a strong laxative to remove any traces of vancomycin and bacteria
  3. a proton-pump inhibitor which reduces the amount of acid in the stomach in the hope that this would increase the survival rate of the donor bacteria
  4. healthy gut bacteria from a donor for 7 to 8 weeks, called Standardized Human Gut Microbiota (SHGM)

Two years later, the children and their parents completed various assessments of their autistic and gut symptoms. Sixteen children provided a stool sample to measure their gut bacteria.

What were the basic results?

With regards to the gut:

  • there was a 58% reduction in symptoms according to the Gastrointestinal Symptom Rating Scale (GSRS) – a checklist that looks at symptoms such as constipation, diarrhoea and bloating
  • abnormal stools (such as watery or hard stools) occurred less frequently – on a quarter fewer days than before
  • most children had a wider range of gut bacteria

According to the Childhood Autism Rating Scale (CARS):

  • a reduction of 47% in signs of autism
  • 3 children were rated as severe, compared to 15 before the treatment
  • 7 were rated as mild-moderate
  • 8 were below the cut-off level for an autism diagnosis

Parent-rated assessments also showed improvements:

  • 8 of the children were rated as severe on the Social Responsiveness Scale (SRS) compared to 16 before the treatment
  • scores on the Aberrant Behavior Checklist (ABC) were 35% lower

Children with improvements in gut symptoms were more likely to have also had reduced signs of autism.

How did the researchers interpret the results?

The researchers concluded that: “These encouraging observations demonstrate that the intensive MTT [Microbiota Transfer Therapy] intervention is a promising therapy for treating children with ASD who have GI problems.” They “recommend future research including double-blind, placebo-controlled randomized trials with a larger cohort.”


This small study shows promise for this treatment protocol, but as the researchers are quick to point out, the results need to be verified in a much larger, placebo-controlled trial.

At this early stage, we don’t know whether the improvements observed were due to the placebo effect as the study was not blinded.

Also, it could be 1 or a few aspects of the treatment protocol that made the difference rather than all 4 steps. For example, the stomach acid suppressant may have been the key factor.

Though the researchers excluded children with specific gut diagnoses such as ulcerative colitis, they did not perform any investigations. This means that there may have been a wide variety in the causes which could explain why some improved and others did not.

Finally, 12 of the children had changed their usual medication, supplements or diet during the course of the 2 year follow-up which could have affected the results.

NHS Attribution