Christian Beltran

 Introduction. Autism spectrum disorder (ASD) is a neurodevelopment disorder that presents with early deficits in social communication and unusual restricted and repetitive behaviors.1 It has been established that the gut microbiome differs between children with ASD with functional gastrointestinal disorders and neurotypical (NT) children functional gastrointestinal disorders.2,3 There is a strong link between the gut microbiota and the central nervous system, known as the microbiome-gut-brain axis. There is a strong interplay between the two, and each plays a role in influencing the other through neural, endocrine, and immune signaling.1 Though the species of altered microbiota reported differ between many studies, it is consistently different when compared to NT individuals. More importantly, there is a strong tie to the altered microbiota and the manifestations of not just gastrointestinal issues but also the ASD related behaviors.4-6 Therefore, it is proposed that by altering the gut microbiome to match NT children that they may be able to alleviate some of the GI and behavioral symptoms associated with ASD. Methods. Finally, children with moderate to severe gastrointestinal problems and autism spectrum disorder were enrolled in an open label clinical trial to determine if microbiota transfer therapy (MTT) could improve both their GI symptoms and ASD-related symptoms. The children who participated in the study received 10 weeks of MTT followed by 8 weeks of observation. Participants were then compared to NT children who did not receive therapy but for monitored for 18 weeks.7 Results. Upon evaluation, GI symptoms using the Gastrointestinal Symptom Rating Scale (GSRS), and ASD symptoms using the Parent Global Impressions III (PGI-III), Childhood Autism Rating Scale (CARS), Aberrant Behavior Checklist (ABC), and the Social Responsiveness Scales (SRS) showed marked improvement after MTT treatment. This suggests that GI symptoms and ASD symptoms showed improvement. Additionally, bacterial diversity increased and there were significant increases in Bifidobacterium, Prevotella, and Desulfovibrio in the ASD patients post MTT. These findings were still present in the ASD patients following an 8-week follow-up period.7  Conclusions. Though this open-label trial showed promise in the treatment of GI and ASD related symptoms in the ASD population, it was a small trial and larger trials will be needed in the future. As well as, a double-blind trial will be needed to rule out any placebo effect of this treatment. However, the fact that the changes in the microbiome were still present after 8 weeks of follow up suggest that this is a very viable option as we progress forward.

1. Strati F, Cavalieri D, Albanese D, et al. New evidences on the altered gut microbiota in autism spectrum disorders. Microbiome. 2017;5(1):24.
2. Luna RA, Oezguen N, Balderas M, et al. Distinct Microbiome-Neuroimmune Signatures Correlate With Functional Abdominal Pain in Children With Autism Spectrum Disorder. Cell Mol Gastroenterol Hepatol. 2017;3(2):218-230.
3. Son JS, Zheng LJ, Rowehl LM, et al. Comparison of Fecal Microbiota in Children with Autism Spectrum Disorders and Neurotypical Siblings in the Simons Simplex Collection. PLoS One. 2015;10(10):e0137725.
4. Hsiao EY, McBride SW, Hsien S, et al. Microbiota modulate behavioral and physiological abnormalities associated with neurodevelopmental disorders. Cell. 2013;155(7):1451-1463.
5. Finegold SM, Summanen PH, Downes J, Corbett K, Komoriya T. Detection of Clostridium perfringens toxin genes in the gut microbiota of autistic children. Anaerobe. 2017.
6. Lim JS, Lim MY, Choi Y, Ko G. Modeling environmental risk factors of autism in mice induces IBDrelated gut microbial dysbiosis and hyperserotonemia. Mol Brain. 2017;10(1):14.
7. Kang DW, Adams JB, Gregory AC, et al. Microbiota Transfer Therapy alters gut ecosystem and improves gastrointestinal and autism symptoms: an open-label study. Microbiome. 2017;5(1):10.