ADHD & Autism

Fecal transplants for autism deliver success in clinical trials

Fecal transplants for autism deliver success in clinical trials
A two-year study on fecal transplants for autism has found they can reduce symptoms by as much as 45 percent
A two-year study on fecal transplants for autism has found they can reduce symptoms by as much as 45 percent
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New research sheds new light on the connection between gut health and autism
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New research sheds new light on the connection between gut health and autism
A two-year study on fecal transplants for autism has found they can reduce symptoms by as much as 45 percent
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A two-year study on fecal transplants for autism has found they can reduce symptoms by as much as 45 percent
The team of ASU researchers behind the new study, left to right, Rosa Krajmalnik-Brown, James Adams, and Dae Wook Kang were inspired to explore the gut-brain connection as it relates to autism symptoms and gastrointestinal issues
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The team of ASU researchers behind the new study, left to right, Rosa Krajmalnik-Brown, James Adams, and Dae Wook Kang were inspired to explore the gut-brain connection as it relates to autism symptoms and gastrointestinal issues
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Scientific research continues to uncover interesting connections between the gut microbiome and human health, including everything from depression to PTSD to autoimmune disease. Another example of this are emerging ties between gut health and autism. Exciting new research, now moving to Phase 3 human trials, has found boosting microbial diversity via fecal transplants can dramatically reduce autism symptoms in the long term.

Editor's note: Readers often ask us for follow-ups on memorable stories. What has happened to this story over the years? This article was originally published in 2019 but it has been re-edited and updated with new information current as of April 7, 2025. Enjoy!

One in every 59 children born in the US is diagnosed with autism, according to the Centers for Disease Control and Prevention, and unfortunately for many of them, chronic gastrointestinal issues are a harsh reality of their condition. According to scientists at Arizona State University (ASU), who conducted the current study, around 30 to 50% of people with autism experience serious gut problems like constipation, diarrhea and stomach pain.

"Many kids with autism have gastrointestinal problems, and some studies, including ours, have found that those children also have worse autism-related symptoms," ASU's Rosa Krajmalnik-Brown said back in 2019 during the early stages of the work. "In many cases, when you are able to treat those gastrointestinal problems, their behavior improves."

A key study in 2019 built on earlier research from 2017 that found introducing new bacteria via fecal transplants in 18 autistic children brought about marked improvements in their behavior, as measured through questionnaires assessing their social skills, hyperactivity, communication and other factors.

These improvements held for eight weeks, an impressive outcome to be sure. But the Arizona State University researchers then set out to investigate the enduring effects of the treatment, which involved a bowel cleanse and daily transplants of fecal microbiota over a period of seven to eight weeks. Prior to the treatment, these children all had far lower diversity of gut microbes than those without autism.

"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," Krajmalnik-Brown said in 2019.

The team of ASU researchers behind the new study, left to right, Rosa Krajmalnik-Brown, James Adams, and Dae Wook Kang were inspired to explore the gut-brain connection as it relates to autism symptoms and gastrointestinal issues
The team of ASU researchers behind the new study, left to right, Rosa Krajmalnik-Brown, James Adams, and Dae Wook Kang were inspired to explore the gut-brain connection as it relates to autism symptoms and gastrointestinal issues

Two years after the treatment, the researchers found that not only did the benefits persist, they seemed to improve. Doctors observations at the eight-week mark found that psychological autism symptoms of the patients had decreased by 24%. But two years later those symptoms had almost been cut in half, with a professional evaluator finding a decrease of 45% in autism symptoms compared to baseline.

Prior to the study, 83% of participants had "severe" autism. Two years later, only 17% were rated as severe, 39% as mild or moderate, and incredibly, 44% were below the cut-off for mild ASD.

"We are finding a very strong connection between the microbes that live in our intestines and signals that travel to the brain," Krajmalnik-Brown said in 2019. "Two years later, the children are doing even better, which is amazing."

The next steps were larger placebo-controlled clinical trial designed to verify their results, with a view to gaining FDA approval for the therapy.

In early 2022 Krajmalnik-Brown and colleagues patented a specific bacterial formulation and spun-off a commercial company called Gut-Brain Axis Therapeutics. The treatment, dubbed Microbiota Transplant Therapy (MTT), moved through a Phase 2 human placebo-controlled trial over the following years and the initial data has been incredibly promising.

"Our phase 2 study for adults with autism found that the treatment group improved more than placebo on the primary outcome (autism symptoms) and on a secondary outcome (daily stool record)," the researchers explain. "Evaluation of symptoms on the Parent Global Impressions found that the treatment group at the end of part 2 improved more than the placebo group in part 1 on nearly all symptoms, with statistically significant improvements in GI, receptive language, and average of all symptoms. There were also marginally significant improvements in tantrums, stimming/perseveration, and cognition."

Now, the team is looking to raise funds to move through the large-scale Phase 3 trials necessary for final FDA approval.

The team's key 2019 study appears in the journal Scientific Reports, and you can hear from the researchers about their most recent findings in the video below.

Source: Arizona State University

Microbiota Transplant for Adults with Autism by Prof. James Adams

An earlier version of this article written by Nick Lavars was published in 2019.

Editor's note: A prior version of this article used the term 'autism sufferers' in reference to people with autism. We understand that terminology is inappropriate and can be deemed offensive. The article has been edited to remove the reference.

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9 comments
9 comments
Jonathan Clark
"sufferer"?
I made an account just to call you out on that. We dint "suffer" from Autism.
Aaron
Autism "sufferers"? Seriously. I'm autistic. Not an autism "sufferer". It has pros *and* cons. It's not a disease. It's just part of who I am. I don't appreciate this medicalization of a core aspect of my personality as if it's something wrong with me.
Karmudjun
Good article Rich, and I remember the previous article. I see those on the spectrum may be triggered by terms used to describe them and the people who interface with them - as all illnesses have "sufferers" both patients and their associates. As we tease out the influence of the gut biome on our metabolism, our neurological perceptions, and our health, we are finding more benefits of fecal transplants. If only we had a therapy for malignant Narcissism, America (USA) could be great again! Thanks for the Article Rich - your words were well placed as were Nick's even if the ASU researchers words triggered some of the readers. I know many who suffer with Autism.
PCA
Karmudjin, I can think of someone in this thread who could use a therapy for Malignant Narcissism, and it is not myself, Clark, or Aaron.
Its true, Autism is a spectrum, and some on the far end of it, have a great deal of difficulty functioning in society as it has been designed. Unfortunately, autism has recently become dangerously politicized, in no small part thanks to the thoughtless words of RFK, and your own words betray you in this regard. That this veritable fringe science is coming from a deep red state isn't lost on me. Autism is not a disease, and we've established people with autism aren't "sick". You need to learn to speak their language and understand their world, instead of trying to eradicate them to suit yours.
MQ
"Severe" is little different to "suffer".. High grade Autism may be a more general phrase to normalise.
Or if one wishes to stay with terminology... Low functioning would be equivalent to High Grade AS Individuals. ( The D may offend)...
Techutante
I am a depression sufferer, I wouldn't say that it's a disease either. I'd still be happy to have fewer effects from it. It's part of my core personality, but really does it have to be? Are we fanboys for our heath conditions?
Nobody
I remember when the only people studying gut biology where the autoimmune sufferers and they were considered odd. Now everyone wants to get onboard.
nopria
Such connections between the gut microbiome and health, including autism (which is a disease, not a trait), were correctly envisioned in a very interesting book a few years ago, “Missing Microbes,” by Martin Balser. I recommend its reading to everyone.
JL85
To those saying you don't "suffer" from autism, I've known multiple people including my own son who definitely do "suffer" and desperately wish they weren't autistic.
Please keep that opinion to yourselves, because you don't represent all autistic people.