Acknowledging microbial dysbiosis as a cause rather than a symptom of ASD, could make it easier to treat or mediate the progression of ASD in children.

Autism and the Microbiome

Posted Connie Shoemaker, ND Blog

Autism and the microbiome, two buzz words that have been getting quite a bit of attention recently as more research emerges suggesting their connections.

The “Second Brain”

It is first important to know that about 80% of the estimated 100 trillion microbes in and on our bodies is located in the gut.[1] Our gut, or gastrointestinal (GI) system, is part of the enteric nervous system (ENS), a division of the autonomic nervous system that functions and responds to stimuli without conscious cues. The ENS is often referred to as our “second brain,” as it made up of several neurons, glial cells, and plexuses that work together to digest our meals and move materials through the intestines. For the most part, these neurons are not connected to the central nervous system (CNS) and send signals independently from brain stimuli.[2] This is unique because the CNS controls all other neuronal pathways in the body.

To add to the complexity, our gut microbiome also has a major influence on gut-brain signaling. Microbes play an important role in maintaining homeostasis and regulating our mood. However, there is a delicate balance between “good,” or commensal, bacteria to “bad” bacteria in the gut. Disruption in this balance can result in dysbiosis of gut microbiota. Dysbiosis can occur due to extensive use of antibiotics, chronic stress, poor diet and nutrient deficiencies, and the use of certain medications.[3] There’s significant evidence connecting mood disorders such as anxiety to gut dysbiosis in conditions like inflammatory bowel disease (IBD).[4]

The Autism Connection

As many know, autism spectrum disorder (ASD) is a neurobehavioral disease affecting millions of people and on the rise in recent decades. Since the underlying cause isn’t strictly genetic, much research has been focused on the possible environmental connections between symptoms and diagnosis. A clue may lie in the prevalence of gastrointestinal disorders in ASD patients.[5] In a study comparing gut microbiota in children with ASD to children without ASD, affected children were found to have a greater concentration of Clostridia and lower concentrations of Prevotella and Coprococcus (microbes involved in carbohydrate metabolism), regardless of gut symptoms. A study published in Microbiome found that altering the gut microbiota profile via microbiota transfer therapy (MTT) alleviated GI symptoms and ASD symptoms for up to eight weeks in ASD-diagnosed children.[6] These findings suggest that some of the underlying mechanisms causing ASD could be attributed to gut dysbiosis, as opposed to the alternative assumption that ASD causes dysbiosis.[7] Acknowledging microbial dysbiosis as a cause rather than a symptom of ASD, could make it easier to treat or mediate the progression of ASD in children.

Microbial Intervention

Treatment of gut dysbiosis could take on many forms. Probiotics, antibiotic treatment, dietary modifications,[8] and even microbiota transplant[9] show promising signs of changing microbial populations in the gut. As a preventative measure, vaginal deliveries and breastfeeding, when possible, are key actions in establishing healthy and robust microbiomes in infants.[10],[11] Although more research needs to done on this topic, so much about microbes is being discovered every day, giving us new insights in treating and preventing diseases like ASD.

Resources

[1] Wang, H., & Wang, Y. (2016). Gut microbiota-brain axis. Chinese Medical Journal, 129(19
[2] Gershon, M. D. (2011). Behind an enteric neuron there may lie a glial cell. Journal of Clinical Investigation, 121(9), 3386-9.
[3]M. Tidjani Alou, J.C. Lagier, D. Raoult. (2016). Diet influence on the gut microbiota and dysbiosis related to nutritional disorders. Hum Microbiome J, (1) 3–11
[4] Cryan, J. F. and O’Mahony, S. M. (2011), The microbiome-gut-brain axis: from bowel to behavior. Neurogastroenterology & Motility, (23) 187–192.
[5] Rosenfeld, C. S. (2015). Microbiomes and ASD. Drug Metabolism and Disposition, 43(10), 1557-1571.
[6] Dae-Wook Kang, Adams, J. B., Gregory, A. C., Borody, T., Chittick, L., Fasano, A., . . . Caporaso, J. G. (2017). Microbiota transfer therapy alters gut ecosystem and improves gastrointestinal and autism symptoms: An open-label study. Microbiome, 5:10.
[7] Buie, T. (2015). Potential etiologic factors of microbiome disruption in autism. Clinical Therapeutics, 37(5), 976-983.
[8] Buie, T. (2015). Potential etiologic factors of microbiome disruption in autism. Clinical Therapeutics, 37(5), 976-983.
[9] Dae-Wook Kang, Adams, J. B., Gregory, A. C., Borody, T., Chittick, L., Fasano, A., . . . Caporaso, J. G. (2017). Microbiota transfer therapy alters gut ecosystem and improves gastrointestinal and autism symptoms: An open-label study. Microbiome, 5:10.
[10] Buie, T. (2015). Potential etiologic factors of microbiome disruption in autism. Clinical Therapeutics, 37(5), 976-983.
[11] Slattery, J., MacFabe, D. F., & Frye, R. E. (2016). The significance of the enteric microbiome on the development of childhood disease: A review of prebiotic and probiotic therapies in disorders of childhood. Clinical Medicine Insights.Pediatrics, 10, 91-107.

Clinical Contributor

Miranda Satterfield

Miranda Satterfield

Clinical Support Intern at Sanesco Health
Miranda recently obtained her degree in Cellular Molecular Biology from UNCA in Asheville. Hobbies include running, reading, and exploring the artistic world of drawing and painting.
Miranda Satterfield

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    Disclaimer: The information provided is only intended to be general educational information to the public. It does not constitute medical advice. If you have specific questions about any medical matter or if you are suffering from any medical condition, you should consult your doctor or other professional healthcare provider.terfield”]