A review of: Cass, H., Gringras, P., March, J., McKendrick, I., O’Hare, A.E., Owen, L., Pollin, C. (2008). Absence of urinary opioid peptides in children with Autism. Archives of Disease in Childhood DOI: 10.1136/adc.2006.114389

Should parents of children with autism stop purchasing commercially available test of opioid-peptides?

In this previous POST I reviewed a simple study that examined the intestinal system of children with autism in order to test specific hypotheses related to the “Leaky Gut” theory. As is mentioned before, this theory suggests that children with autism have increased permeability of their intestinal track leading to faster absorption of peptides which could disrupt neural development during the early stages of life. However, the Robertson et al. (2008) article did not find evidence that would support the Leaky Gut theory. In this similar study, the authors compared 68 males with autism between 4 and 11 years of age to 202 typically developing males of similar ages. Autism was diagnosed via ADI-R based on ICD-10 diagnostic criteria. Only 6 of the children with autism were on special diets (gluten free or gluten and casein free). The researchers compared the levels of putative opioid peptides in the urine of all participating children. There was no significant difference between the peptide levels of children with autism when compared to typically developing children. The authors concluded that, given this apparent normative absorption and processing of peptides in children with autism, the presence of high opioid -peptides should not be used as a marker for autism or as an estimate of the possible effectiveness of gluten free diets. The researchers also indicated that previous studies showing high levels of opioid peptides in children with autism prior to the start of a gluten free diet (See for example Knivsberg et al 2002), have not been replicated mostly because of possible inadequate methods used in previous studies. The authors feel strongly that “Children with autism should not be subjected to investigation of urinary opioid peptides or their parents to the expense of the assays which are still widely advertised on the internet by commercial laboratories around the world”.

UPDATE: After I reviewed this study I received several emails from parents with different perspectives on the Gluten Free diet issue. I want to briefly note two things. The data from the Cass article do not directly address the issue of effectiveness of the gluten free diets or the issue of the use of peptide tests to predict treatment effectiveness (despite their strong statement against such tests). Their data simply fails to find support for one of the underlying assumptions of the Leaky Gut theory.

Someone also pointed me to what seems to be the only clinical controlled study of these treatments:

Elder JH, Shankar M, Shuster J, Theriaque D, Burns S, Sherrill L.( 2006) The gluten-free, casein-free diet in autism: results of a preliminary double blind clinical trial. J Autism Dev Disord. 36(3):413-20.

In this study, the authors also failed to find statistical evidence for improvement in children exposed to the gluten free diet for 12 weeks. However, this 2006 study was very preliminary with an extremely small sample size. There is no doubt that additional research is needed to help clarify the possible effectiveness of these diets.

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One Response to More evidence against the Leaky Gut theory of Autism?

  1. Regan says:

    For a couple of controlled gluten-free casein-free/autism studies, you might want to keep an eye on these. One study may have preliminary data in April and the other in October.

    http://clinicaltrials.gov/ct2/results?intr=%22Gluten-+and+casein-free+diet%22

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