The mothers of some autistic children may have made antibodies against their fetuses' developing brain tissue during pregnancy that crossed the placenta and caused changes that led to autism, suggests research by Johns Hopkins Children's Center investigators. What causes autism, a disorder manifesting itself with impaired social interactions, communication disorders and repetitive behaviors, remains unknown. Genetic, metabolic and environmental factors have been implicated in various studies of autism, a disorder affecting 1-in-150 U.S. children. "Now our research suggests that the mother's immune system may be yet another factor or a trigger in those already predisposed," says lead investigator Harvey Singer, M.D.
Evidence of immune system involvement in autism has emerged from unusual antibody levels in some autistic children. Antibodies are proteins the body makes in response to viruses and bacteria or sometimes mistakenly against its own tissues. Yet, the majority of children with autism have no clinical evidence of autoimmune diseases, which prompted researchers to wonder whether the antibodies transferred from mother to child during pregnancy could interfere with the fetal brain directly.
Comparing the antibody-brain interaction in samples obtained from 100 mothers of autistic children and 100 mothers of children without autism, researchers found either stronger reactivity or more areas of reactivity between antibodies and brain proteins in about 40 percent of the samples obtained from the mothers of autistic children. Further, the presence of maternal antibodies was associated with so-called developmental regression in children, increasingly immature behaviors that are a hallmark of autism.
While the findings, appearing in the Journal of Neuroimmunology, suggest an association between autism and the presence of fetal brain antibodies, the investigators caution that the findings needn't be cause for alarm, but should be viewed instead as a step forward in untangling the complex nature of autism. "The mere fact that a pregnant woman has antibodies against the fetal brain doesn't mean she will have an autistic child," Singer says. "Autism is a complex condition and one that is likely caused by the interplay of immune, genetic and environmental factors."
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Source: Johns Hopkins Medical InstitutionS
