This is a summary of studies on PubMed. Fecal Matter Transplants (FMT) works well permanently for some conditions, often just for a few months for other conditions, and rarely for other conditions. FMT does have risks to it. It is effectively an organ transplant and we are still learning about “compatible donors”. In a few cases, diseases may be passed; in rare cases deaths have been reported.
- “Preliminary literature suggests that FMT may be a promising treatment option for several neurological disorders. However, available evidence is still scanty and some contrasting results were observed. A limited number of studies in humans have been performed or are ongoing, while for some disorders only animal experiments have been conducted. Large double-blinded randomized controlled trials are needed to further elucidate the effect of FMT in neurological disorders.” 2019
- “An open-label study and a two-year follow-up suggest that MTT is relatively safe and effective in significantly reducing gastrointestinal disorders and autism symptoms, changing the gut microbiome structure, and increasing gut microbial diversity. Further research with larger, randomized, double-blind, placebo-controlled studies is warranted.” 2019
- Microbiota Transfer Therapy (MTT) involved a 2-week antibiotic treatment, a bowel cleanse, and then an extended fecal microbiota transplant (FMT) using a high initial dose followed by daily and lower maintenance doses for 7-8 weeks. … clinical assessments showed that behavioral ASD symptoms improved significantly and remained improved 8 weeks after treatment ended. 2017
- “we report on a follow-up with the same 18 participants two years after treatment was completed. Notably, most improvements in GI symptoms were maintained, and autism-related symptoms improved even more after the end of treatment. ” 
- Only a single reported study on 18 participants is in the literature.
- Following the identical procedure is strongly recommended (often FMT is done as a “one shot” process, this extended doses for 8 weeks may be a very significant factor for it’s success)
- Results were good on a subjective basis.
- Technical issue: There was no control group used
- Suggested donor would be a blood relative (ideally sibling) whose microbiome has been tested and show none of the shifts reported with autism which the target patient has.
- [Speculation] Having the same blood type may contribute to higher success rate.