Improved gut diversity causes 50% reduction in autism symptoms

Changing the microbial environment in the gut in autistic children could substantially reduce the severity of the symptoms they experience, according to new research. The study “Long-term Benefit of Microbiota Transfer Therapy in Autism Symptoms and Gut Microbiota”, was published on 9th April 2019 in the journal, Scientific Reports.

Children with autism can experience severe gastrointestinal symptoms, which can affect behavior.Olesia Bilkei | Shutterstock

Researchers Dae-Wook Kang, PhD., Rose Krajmalnikat-Brown, PhD., and James Adams, PhD. of Arizona State University had previously found that introducing healthy gut microflora led to improvements in both gastrointestinal (GI) and autism symptoms.

The study, which was published in 2017, describes autism spectrum disorders (ASD) as “complex neurobiological disorders that impair social interactions and communication and lead to restricted, repetitive, and stereotyped patterns of behavior, interests, and activities.”

“In our original paper in 2017, we reported an increase in gut diversity together with beneficial bacteria after microbiota transfer therapy (MTT), and after two years, we observed diversity was even higher and the presence of beneficial microbes remained,” explained biotechnological Dae-Wook Kang PhD., lead author.

There is a range of comorbidities observed in people with autism, and the prevalence and severity of gastrointestinal problems seemingly correlate with the severity of the core autism-related behavioral problems individuals experience.

Gastrointestinal symptoms linked to ‘worse autism-related symptoms’

GI symptoms associated with autism include chronic constipation, diarrhea, and abdominal pain, with gastroesophageal reflux and gastritis being reported as well.

Many kids with autism have gastrointestinal problems, and some studies, including ours, have found that those children also have worse autism-related symptoms.”

Dr. Rosa Krajmalnik-Brown, Environmental Engineer

“In many cases, when you are able to treat those gastrointestinal problems, their behavior improves.”

Treatments for ASD include behavioral therapies, speech and social therapies, psychiatric medications, and some nutritional therapies.

Improving the gut microbiome may relieve neurological problems

There are currently no approved medical treatments to help the core symptoms of autism, from difficulties with social communication to repetitive behavior.

However, innovative research is being carried out concerning the gut microbiome, the community of microbes that exist in the intestines and play important roles in digestion, the immune system, and regulating the growth of harmful bacteria. Some research has suggested that the gut microbiome may also be able to relieve neurological problems as well.

For their new study, the researchers used a process called microbiota transfer therapy (MTT), which is a customized process of gut microflora transplantation.

18 children aged between seven and 16 were treated for 10 weeks and attended follow up tests for another eight weeks. The same participants were also involved in the researcher’s previous study two years ago, which trialed microbiota transfer therapy, a type of fecal transplant developed by gastroenterologist Dr. Thomas Borody, combining antibiotics, bowel cleanses, stomach-acid suppressants, and a fecal microbiota transplant (FMT).

GI symptoms improved by 58% on average and were ‘maintained’ and after treatment

Having introduced their new study by stating, “Fecal microbiota transplant[s] could transform the dysbiotic gut microbiome toward a healthy one by delivering a large number of commensal microbes from a healthy donor,” researchers concluded that

Notably, most improvements in GI symptoms were maintained, and autism-related symptoms improved even more after the end of treatment.”

The study acknowledges that the results may be subject to the placebo effect but reports that the long-term benefits experienced by the study participants were “promising”.

The results found show that the improvement was, on average, a 58 percent reduction in the Gastrointestinal Symptom Rating Scale (GSRS). All sub-categories of GSRS, which include abdominal pain, indigestion, diarrhea, and constipation, were subject to these improvements. However, the improvements in indigestion symptoms were reduced after the two-year period when compared with weeks 10 and 18.

After two years, symptoms were 47% lower

Additional to improvements seen in GI abnormalities, the severity of ASD symptoms had also reduced by 47% at the end of the two-year follow-up tests, based on the Childhood Autism Rating Scale (CARS).

83 percent of study participants rated as “severe” on the CARS at the beginning of the original trial. At the two-year follow-up tests, 17 percent were rated as “severe”, 39 percent as “mild to moderate”, and 44 percent were below the ASD diagnostic cut-off scores.

The researchers state that improvements seen on the CARS assessments are “less susceptible to placebo-effect” as CARS is a “stable and consistent diagnostic tool with high predictive validity.”

They were also able to report that:

Changes in gut microbiota persisted at two years, including in overall community diversity […] These encouraging observations demonstrate that the intensive MTT intervention is a promising therapy for children with ASD who have GI problems."

Could microbiota transplants become a routine part of ASD treatment?

Krajmalnik-Brown commented on the work, saying, “Kids with autism are lacking important beneficial bacteria, and have fewer options in the bacterial menu of important functions that bacteria provide to the gut than typically developing kids.”

Kang has said that further studies are needed to properly define the roles gut microbiomes play in the context of autism.

This is a world-first discovery that when we treated the gut bacteria in these children during our clinical trial two years ago to reset their microbiome with FMT, positive results are still continuing to be improving two years from the original treatments. I would call it the highest improvement in a cohort that anyone has achieved for autism symptoms.”

Dr. Thomas Borody

The researchers conclude the study by saying they believe additional research, including double-blind, placebo-controlled randomized trials using larger cohorts would help solidify their findings, which will form the next steps in their research.

Lois Zoppi

Written by

Lois Zoppi

Lois is a freelance copywriter based in the UK. She graduated from the University of Sussex with a BA in Media Practice, having specialized in screenwriting. She maintains a focus on anxiety disorders and depression and aims to explore other areas of mental health including dissociative disorders such as maladaptive daydreaming.


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