A quarterly publication of the Autism Research Institute

The Autism Research Review International is quarterly publication of the Autism Research Institute

Summer, 2018 | Number 3, Volume 32

Follow-up study: Microbiota Transfer Therapy’s behavior, GI benefits still evident after two years

A new study reports that the positive behavioral and gastrointestinal (GI) changes seen in children with autism spectrum disorders (ASD) following fecal transplants appear to be lasting. 

Fecal transplants are currently used as a treatment for C. difficile infection and inflammatory bowel disease. A research team headed by James Adams at Arizona State University has been investigating the potential of this approach for treating children with ASD, who have a high rate of diarrhea, constipation, and other bowel problems that may be connected to their behavioral issues. 

In their initial study (see ARRI 31/1, 2017), led by Dae-Wook Kang, 18 participants with ASD and GI problems underwent Microbiota Transfer Therapy, or MTT. Participants first received two weeks of antibiotic treatment and a bowel cleanse to prepare the GI tract. Next, they received one high dose of microbiota administered either orally or rectally, followed by a lower oral daily maintenance dose for 7 to 8 weeks. The researchers used a standardized product containing more than 99% bacteria obtained from healthy individuals and tested to ensure safety. The children also took an acid pump inhibitor to reduce stomach acidity and increase the survival rate of the microbes. 

In the initial study, the researchers followed up on the children for eight weeks after treatment ended. Among their findings: 

• The average score on the Gastrointestinal Symptom Rating Scale (GSRS) dropped 82% from the beginning to the end of treatment. At the eight-week follow-up, it remained 77% lower than at baseline. 

• Only two of the 18 children with ASD showed less than a 50% reduction in the average GSRS score. 

• There was a significant decrease in the number of days with abnormal or no stools, and this improvement also was maintained at the eight-week follow-up. 

• The Parent Global Impressions-III (PGI-III) scale revealed significant improvements in behavior, and there was a significant correlation between GSRS scores and PGI-III scores.      

• Scores on the Childhood Autism Rating Scale, which measures core autism symptoms, decreased by 22% from the beginning to the end of the study, and were 24% lower than baseline at the eight-week follow-up. 

• Participants with ASD also showed improvements on the Social Responsiveness Scale and the Autism Behavior Checklist. 

• On the Vineland Adaptive Behavior Scale II, the average developmental age of participants with ASD increased by 1.4 years and improved across all domain areas. 

The researchers also detected significant changes in the gut bacteria of the children with ASD. While these children initially had significantly less diverse gut bacteria than controls, the researchers noted that “median richness at week 18 was statistically indistinguishable between the ASD and control groups.” 

In the new study, led by Rosa Krajmalnik Brown, the researchers followed up with all 18 participants two years after treatment stopped. “Notably,” they say, “gastrointestinal symptoms were significantly reduced compared with the beginning of the original trial, and autism-related symptoms improved significantly after the end of treatment.” In addition, they say, “DNA-sequencing analyses revealed that changes in gut microbiota at the end of treatment still remained at follow-up, including significant increases in bacterial diversity and relative abundances of Bifidobacteria, Prevotella, and Desulfovibrio.” 

They conclude, “Our observations demonstrate the long-term efficacy of MTT for treating children with ASD who have GI problems. The microbiota transfer therapy performed in this trial thus is a promising approach for sustainably altering the gut bacterial communities, and improving gastrointestinal and behavioral symptoms associated with ASD.”

The researchers say that at their follow-up two years after the initial study, “gastrointestinal symptoms were significantly reduced compared with the beginning of the original trial, and autism-related symptoms improved significantly after the end of treatment.”


“2-year follow-up study reveals consistent benefits of microbiota transfer therapy on autism and gut symptoms,” Rosa Krajmalnik-Brown, DaeWook Kang, Devon Coleman, Elena L. Pollard, Juan Maldonado, Sharon McDonough-Means, J. Gregory Caporaso, and James B. Adams. The researchers’ findings were presented at the Beneficial Microbes Conference on July 10, 2018.