A new study suggests that autism is associated with a reduction in the level of cellular adhesion molecules in the blood.
These molecules are the glue that binds cells together in the body, researchers said, noting that, in the brain, deficits in adhesion molecules could compromise brain development and communication between nerve cells.
Over the years, deficits in neural cell adhesion molecules have been implicated in schizophrenia and other psychiatric disorders, according to researchers. One adhesion molecule, neurexin, has been strongly implicated in the risk for autism.
Cell adhesion molecules also play a crucial role in regulating immune cell access to the central nervous system, the researchers point out, noting that previous research has provided evidence of immune system dysfunction in individuals diagnosed with autism spectrum disorder (ASD).
This led scientists from the University of California, Davis to examine whether adhesion molecules are altered in children with ASD.
They recruited children between the ages of 2 and 4, including 49 diagnosed with an ASD and 31 who were typically developing. They measured blood plasma levels of multiple molecules, conducted behavioral assessments, and measured head circumference in all the children.
“For the first time, we show that levels of soluble sPECAM-1 and sP-selectin, two molecules that mediate leukocyte migration, are significantly decreased in young children with ASD compared with typically developing controls of the same age,” the researchers said in the study, which was published in Biological Psychiatry.
“This finding is consistent with previous reports of decreased levels of both sPECAM-1 and sP-selectin in adults with high-functioning autism.”
The researchers also found that repetitive behavior scores and sPECAM-1 levels were associated in children with ASD. Repetitive behaviors are a typical feature of ASD, the researchers said, noting that their data suggest a potential relationship between molecule levels and the severity of repetitive behaviors.
Finally, the study also discovered that head circumference was associated with increased sPECAM-1 levels in the typically developing children, but not in the children with ASD. This indicates that perhaps sPECAM-1 plays a role in normal brain growth, as larger head circumference is a known feature of individuals with autism.
“The report of reductions in adhesion molecules in blood in autism is interesting in light of recent genetic findings. However, the importance of these measurements remains somewhat uncertain,” said Dr. John Krystal, editor of Biological Psychiatry.
“Our field continues to look for blood tests that might inform the diagnostic and treatment process.”