Fecal microbiota transplantation (FMT) is a medical procedure involving the transfer of stool from a healthy donor to a recipient. The aim of this process is to introduce a diverse community of beneficial microbes into the recipient’s gastrointestinal tract, thereby restoring a balanced gut microbiome. This approach is currently being investigated for its potential to improve certain symptoms associated with autism spectrum disorder (ASD). This exploration stems from observations linking gut health to neurological function, suggesting that a healthier gut could influence aspects of ASD.
The Gut-Brain Connection in Autism
A complex communication network, often referred to as the gut-brain axis, links the gastrointestinal system directly to the brain. This bidirectional pathway facilitates the exchange of signals between the gut microbiome, the nervous system, and the immune system, influencing both gut health and brain function. Many individuals with ASD frequently experience significant gastrointestinal (GI) issues, such as chronic constipation, diarrhea, and abdominal pain. The prevalence of GI disorders in individuals with ASD is considerably higher than in the neurotypical population.
Research has identified differences in the composition of gut bacteria in individuals with ASD compared to neurotypical individuals. Studies have shown that children with ASD often have reduced microbial diversity and an increased presence of certain bacteria like Clostridium and Bacteroides. These microbial imbalances, sometimes referred to as dysbiosis, are hypothesized to contribute to both GI problems and potentially influence ASD-related behaviors through the gut-brain axis. For instance, some gut bacteria produce metabolites like propionic acid, which has been linked to autistic-like behaviors in animal models.
Investigating Fecal Transplants as a Treatment
Scientists are exploring fecal transplants as a way to address the gut microbiome imbalances seen in ASD, with the hope of alleviating associated symptoms. A notable study from Arizona State University (ASU) investigated the effects of microbiota transfer therapy (MTT) on children with ASD aged 7 to 16 years. This treatment involved a 10-week program, including initial antibiotic treatment and bowel cleansing, followed by daily fecal microbiota transplants for seven to eight weeks.
The reported outcomes from this research indicated improvements in both gastrointestinal symptoms and certain core ASD-related behaviors. By the end of the treatment, participants showed an approximate 80% reduction in GI symptoms. Concurrently, autism-related symptoms demonstrated improvements of about 20-25%. These behavioral changes included enhancements in social skills and sleep habits.
Long-term follow-up studies on the same participants revealed the persistence and even further improvement of these changes. Two years after the initial treatment concluded, the children maintained an average of a 58% reduction in GI symptoms compared to their baseline levels. Furthermore, professional evaluations indicated a 45% decrease in core ASD symptoms, such as language, social interaction, and behavior, compared to before the treatment began. At the study’s start, 83% of participants were classified with “severe” autism; two years later, only 17% remained in the “severe” category, with 44% falling below the cutoff for mild ASD.
The Fecal Transplant Procedure
The fecal transplant procedure begins with the careful selection of a healthy donor. Donors undergo rigorous screening, which includes a detailed medical history, infectious disease risk assessment, and clinical evaluation to rule out transmissible diseases and other health conditions that could affect the gut microbiome. This comprehensive screening involves blood and stool tests to rule out infectious diseases and other pathogens. Donors are generally between 18 and 50 years old, as the microbiome is considered most stable during this period.
Once a suitable donor is identified, their stool sample is collected and processed in a laboratory. This involves mixing the stool with a solution and straining it to remove solids. The prepared fecal material can be used fresh or cryopreserved for later use.
The processed stool is then administered to the recipient through various methods. Common routes include colonoscopy, where the material is delivered directly into the colon, or via nasoduodenal tube, which involves a tube inserted through the nose into the small intestine. Encapsulated pills are also being developed and used as an oral administration method, offering a less invasive option.
Safety, Risks, and Regulatory Standing
Fecal microbiota transplantation, while showing promise, carries potential risks and side effects. Mild and temporary gastrointestinal discomfort can occur after the procedure. More serious risks, though rare, include the potential for transmitting harmful pathogens if donor screening is not thorough. There have been instances where patients acquired severe infections from improperly screened donor stool.
The U.S. Food and Drug Administration (FDA) considers FMT for autism an investigational treatment and has not approved it as a standard therapy. The FDA has issued safety warnings regarding the potential risks of infection from FMT. Consequently, FMT for conditions other than recurrent Clostridioides difficile infection should only be performed under strict medical supervision, typically within the framework of a clinical trial.
Engaging in do-it-yourself (DIY) fecal transplants is strongly discouraged due to severe health dangers. Without proper medical screening of donors and sterile preparation of the stool, there is a substantial risk of introducing dangerous bacteria, viruses, or parasites into the recipient. The absence of professional oversight also increases the risk of procedural complications, making DIY approaches highly unsafe.