Gluten Sensitivity Linked To Autism: findings are only a part of a very complicated puzzle
The gluten free diet’s popularity has been growing in the autism community for some years but recent studies show that this approach may not be supported by clinical evidence.
A recent study released on June 18, 2013, shows that a subset of children with autism have increased immune reactivity to gluten. The goal the study is to determine if there is a relationship between gluten-related immune system abnormalities and autism. Dr. Alaedini, assistant professor of medical science in Department of Medicine and the Institute of Human Nutrition at Columbia University Medical Center, explained that “There is evidence that immune system abnormalities are associated with symptoms in a substantial number of individuals with autism.” Researchers discovered that there may be an association between gluten sensitivity and autism but the mechanism of that reaction is distinct form what we see in people with celiac disease.
Study Design
The study, funded by the US Department of Defense, analyzed blood samples from 37 children with autism, 27 unaffected siblings and 76 age-matched, unrelated healthy controls. The blood samples were tested for three things:
1. a sensitive and specific marker of celiac disease (antibodies to tissue transglutaminase)
2. IgG and IgA antibodies to gliadin proteins
3. Genetic markers for celiac disease (HLA-DQ2 and HLA-DQ8 alleles)
By testing for celiac-specific markers as well as markers that simply indicate a response to gluten, researchers could delineate between a higher rate of celiac in children with autism versus a higher rate of gluten sensitivity in children with autism.
Findings
The study found that children with autism had significantly higher levels of IgG antibodies to gliadin compared with the children in the study without autism (the control group).
When taking a closer look at the 37 children with autism, researchers found that autistic children with GI symptoms had a significantly higher level of IgG in their blood compared to autistic children without GI symptoms. Interestingly, when tested for IgA antibodies, researchers did not find a difference between the autistic children with GI symptoms and the autistic children without GI symptoms.
IgG vs IgA
IgA antibodies – can be found in the gut mucosa and indicate immune function of the inner lining of the gastrointestinal tract.
IgG antibodies – most abundant type of antibody; can be found in all body fluids and indicate an overall immune response
When tested for a celiac-specific marker, the blood samples showed no statistically significant difference among the testing groups. Furthermore, when tested for the genetic markers of celiac disease (HLA-DQ2 and HLA-DQ8 alleles) researchers did not find an association between autism and celiac disease.
Researchers concluded that children with autism were more likely to have gluten-related antibodies present in their blood but did not show any indications of the presence of celiac disease.
Adding more pieces to the puzzle
Even with this latest study, the association between gluten sensitivity and autism is still uncertain. If anything, the findings of this study lead to even more questions about whether or not a gluten free diet may help children with autism. The presence of IgG antibodies in children with autism only indicates that there has been a large immune reaction but gluten may not actually be the cause of that reaction.
According to Dr. Dan Coury, medical director of the Autism Speaks Autism Treatment Network, “By themselves, antigliadin antibodies do not mean disease. They are part of the whole puzzle. When they occur with other abnormalities and with symptoms, we begin to get a clearer picture. As the authors note, these findings deserve further study. It may be that this will help identify a subgroup of individuals with autism who might benefit from a specific treatment someday, when we have a better understanding of just what is going on here.”
Although the study cannot definitively tell us if there is a link between gluten exposure and autism, the study does tell us that there is a relationship between autism and the immune system. This new insight should lead to further studies that may develop new treatments for autism. Dr. Alaedini drives this point home by explaining that “Having a clearer understanding of the immunologic differences in the affected children can give us novel clues about the mechanism of autism, such as the potential involvement of immune-mediated pathways. These clues, in turn, may lead to new treatments that, for example, target those specific immune pathways.”
Although many sources report that a gluten free diet may help children with autism, so far that claim is not supported by research. There has yet to be a controlled and blinded study that supports the claim; however, studies are getting us closer and closer to better understanding autism.
Authors: Nga M. Lau, Peter H. R. Green, Annette K. Taylor, Dan Hellberg, Mary Ajamian, Caroline Z. Tan, Barry E. Kosofsky, Joseph J. Higgins, Anjali M. Rajadhyaksha, Armin Alaedini
Source: Medscape