More News about the Gut's Role in Autism

Last week, I highlighted new evidence about the link between gluten and the symptoms of autistic spectrum disorder (ASD).  Hot off the presses, we have another study about a gut-autism link.  Researchers at Arizona State University (1) found a significant difference between the normal flora (bacteria in the gastrointestinal tract) of children with autism and non-autistic children.  In particular, autistic children had lower levels of three types of bacteria:  Prevotella, Coprococcus, and Veillonellaceae.  These were identified from fecal samples taken from children ages 3 to 16 years.  These organisms, especially Prevotella, are important for carbohydrate digestion, and maintenance of healthy biodiversity in the gut ecosystem.  Impairment of carbohydrate digestion may leave these kids more susceptible to developing the leaky gut and gluten sensitivity described in last week's article.

While this research is intriguing, it still presents us with a chicken-or-egg dilemma: do disturbances of gut bacteria contribute to the development of ASD, or are children with ASD more susceptible to gut flora imbalances by some other mechanism?  We are only in the very early stages of identifying all the complexities of the trillions of microorganisms that live inside of us.  Now that we have identified the human genome, the next step is to tackle the human microbiome:  the identification of all of those microbial species in their proper proportions to maintain good health.

Over the next 20 years or so, our current probiotics supplements will look like primitive stone tools.  Hopefully, we can get to the stage where we can supplement with specific organisms like the ones identified in this study (none of which are available in current probiotics supplements).  Otherwise, we may have to look more seriously at fecal microbiota transplantation as an important technique for many health conditions, not just C. difficile infection.

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1.  Kang D-W, Park JG, Ilhan ZE, Wallstrom G, LaBaer J, et al. (2013) Reduced Incidence of Prevotella and Other Fermenters in Intestinal Microflora of Autistic Children. PLoS ONE 8(7): e68322. doi:10.1371/journal.pone.0068322

New Evidence on the Link between Gluten and Autism

Rates of autism have been on the rise in the US over the last few decades.  The exact cause of this is unknown; part of the reason may be due to an increased degree of awareness and diagnosis.  This uncertainty is reflected in a major change to the fifth edition of the American Psychiatric Association's Diagnostic and Statistical Manual (DSM-5): the terms autistic disorder, Asperger's syndrome, and pervasive developmental disorder have been replaced by the single umbrella term autistic spectrum disorder (ASD).  Holistic doctors and concerned parents continue to search for therapies that can help mitigate the symptoms of autism in any way.  One of the cornerstones of this natural approach has been a gluten-free diet.

The theory behind this is that children with ASD are particularly susceptible to a compromised barrier in the gastrointestinal (GI) tract -- a condition known as "leaky gut".  This allows larger "chunks" of protein to make it into the bloodstream without being fully digested.  Gluten, the main protein in wheat and related grains, can contribute to this GI damage.  The gluten protein in the bloodstream can also stimulate an immune system response; the resulting inflammation can have an impact on the nervous system, exacerbating autistic behaviors.

New research out of Italy (1) demonstrated that children with ASD have a higher rate of IgG antibodies to gluten than healthy children of the same age.  They did not have higher rates of lab markers for celiac disease, such as tissue transglutaminase antibodies, and the HLA-DQ2 and HLA-DQ8 genes.  This indicates that there is a continuum of sensitivity to gluten other than full-blown celiac disease.

While the authors of the study are cautious in their interpretation of these results, it just adds more support to the naturopathic approach of a gluten elimination diet, along with nutritional and herbal therapies to help repair the lining of the GI tract.  A gluten-free diet is not easy under the best of circumstances in our culture; for autistic children, who often have very strong food preferences, it can be even more difficult.  However, with the prospect of significant behavioral improvement, it's definitely worth a try.

1.  Lau NM, Green PHR, Taylor AK, Hellberg D, Ajamian M, et al. (2013) Markers of Celiac Disease and Gluten Sensitivity in Children with Autism. PLoS ONE 8(6): e66155. doi:10.1371/journal.pone.0066155