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More Evidence Linking Immune System to Some Forms of Autism

Children with regressive forms of autism show greatest signs of ongoing inflammation


Cytokines produced by immune cells such as these can disrupt the function of nerve cells.In January, researchers at the University of California, Davis, reported evidence that many children with autism spectrum disorder (ASD) have signs of ongoing inflammation. They found levels of inflammatory markers called cytokines to be higher in children with autism than in those who did not have the disorder. Further analysis showed that the increased levels of cytokines occurred primarily in children who had a regressive form of autism. Regression refers to a loss of developmental skills such as language and sociability after a period of seemingly normal early development.

In addition, the investigators found that impairment associated with autism increased with elevated cytokine levels. The findings suggest that ongoing inflammation may be linked to some forms of autism and autism-linked disabilities. The researchers called for more study on the implications for diagnosis and treatment of autism’s core symptoms.

The research team, led by immunologist Paul Ashwood, Ph.D., analyzed cytokine levels in blood samples from 223 children ages 2 to 5. Of these, 97 had a confirmed ASD diagnosis, 39 had developmental disorders other than autism, and 87 were typically developing children.

Using blood samples, the researchers measured levels of twelve different cytokines—immune-signaling molecules associated with inflammation. Levels of four of the twelve were significantly higher for children with autism than for children with typical development. Cytokine levels were generally highest in children with regressive forms of autism compared to those with non-regressive forms. The researchers considered a child’s autism “non-regressive” if that child had shown signs of autism from infancy.

Past studies have likewise found evidence that immune system abnormalities are more common in children with ASD than in typically developing children. This study is the largest to date looking specifically at levels of cytokines, which may influence brain development and behavior.

Further research is needed to confirm these findings and explain the association between these inflammatory markers and autism. It is unclear, for example, whether inflammation produces or worsens core symptoms or whether both inflammation and autism stem from a common biological issue. The research was funded in part by a grant from Autism Speaks.

Ashwood P, Krakowiak P, Hertz-Picciotto I, et al. Elevated plasma cytokines in autism spectrum disorders provide evidence of immune dysfunction and are associated with impaired behavioral outcome. Brain, Behavior, and Immunology. 2011;25(1):40-5.


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