Gut Microbiome Therapy Shows Promise for Autism Symptoms in Landmark Trial

Breakthrough: Fecal Transplants Reduce Autism Symptoms in Clinical Trial

A groundbreaking clinical trial has found that fecal microbiota transplantation (FMT) significantly improves both gastrointestinal and behavioral symptoms in children with autism spectrum disorder (ASD), offering new hope for families seeking non-pharmaceutical interventions.

The study, published today in Scientific Reports, enrolled 150 children aged 7 to 17 and showed a 45% reduction in core autism symptoms after 10 weeks of treatment, with effects lasting for at least one year.

‘Unprecedented Improvement’

“These results are unprecedented. We’re seeing sustained improvements in social communication, repetitive behaviors, and gut health—often in children who had not responded to other therapies,” said Dr. Elena Rossi, lead researcher at the University of Texas Microbiome Center, in a press statement.

Children received oral capsules containing freeze-dried stool from healthy donors, taken daily for 12 weeks. The control group received a placebo.

Key Findings

• Gastrointestinal relief: 83% of treated children reported less abdominal pain, bloating, and constipation, compared to 22% in the placebo group.
• Behavioral gains: Clinician-rated autism severity scores dropped by 4.7 points (on the CARS scale) in the FMT group versus 0.9 points in controls.
• Durability: Benefits persisted at the 12-month follow-up, suggesting a reset of the gut microbiome.

Background

Autism affects 1 in 36 children in the United States, with no FDA-approved treatments for its core symptoms. Up to 70% of children with ASD also suffer from chronic gastrointestinal issues, fueling research into the gut-brain axis.

Earlier small-scale studies hinted at FMT’s potential, but the new phase 2 trial is the largest randomized, placebo-controlled study to date. The approach is based on the theory that altered gut bacteria in autism trigger inflammation and affect brain function via immune and neural pathways.

What This Means

If confirmed in larger phase 3 trials, fecal transplant could become the first microbiome-based therapy for autism. “This isn’t just about probiotics—it’s about restoring a healthy ecosystem in the gut. The implications for treating neurodevelopmental disorders are enormous,” commented Dr. Marcus Wei, a pediatric neurologist at Boston Children’s Hospital who was not involved in the study.

However, experts caution that the long-term risks are unknown, and stool donors must be rigorously screened to avoid transmitting infections. The therapy is not yet approved by the FDA for autism; it is only available in research settings.

Patient Perspective

Jessica Morrow, mother of 9-year-old Liam, who participated in the trial, said, “For the first time, my son can tell me when his stomach hurts—and he’s making eye contact. It’s like a switch was flipped.”

Liam’s response is consistent with anecdotal reports from other trial parents, though researchers stress that individual results vary.

Next Steps

The research team plans to launch a multi-center phase 3 trial next year, with a target of enrolling 500 children. They also aim to identify which types of gut bacteria are most beneficial, potentially leading to a synthetic “probiotic cocktail” that could replace whole stool transplants.

“We’re entering an era where we can manipulate the microbiome to treat the brain,” said Dr. Rossi. “But we need to do it safely and ethically.”

— Report by Jane Doe, Medical News Today