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Researchers See Differences in Autism Brain Development as Early as 6 Months

February 17, 2012

Scientists created 3D images of major brain pathways in infants at high risk for developing autism. [Credit: UNC]

The defining features of autism—hampered communication, social challenges and repetitive actions—may not become obvious until after a baby’s first birthday. But the changes in brain development that underlie these behaviors may be detectable much earlier. In a new study, researchers found clear differences in brain communication pathways starting as early as 6 months and continuing through 2 years of age in children who were later diagnosed with autism spectrum disorder (ASD). The findings appear online today in the American Journal of Psychiatry.

“Dynamic brain changes are happening within the first year of life, and these changes are different from what’s happening in the brains of typically developing kids,” says senior author Joe Piven, M.D., director of the University of North Carolina’s Carolina Institute for Developmental Disabilities, in Chapel Hill.

The graphs show average developmental trajectories (right and left brain hemispheres) for one of the 15 major brain pathways studied. Red lines represent the trajectories of infants that went on to develop autism; blue lines for those who did not. [Credit: Joseph Piven, UNC]

It’s too early to tell whether the brain imaging techniques used in the study will be useful in identifying children at risk for ASD in early infancy, Piven says. But the results could guide the development of better tools for predicting the risk that a child will develop ASD and perhaps for measuring whether early intervention therapies improve underlying brain biology.

As part of their Infant Brain Imaging Study (IBIS), Piven and his colleagues followed 92 infants to study early brain and behavior development. Many of these infants had older siblings on the autism spectrum and, so, were at elevated risk of developing ASD themselves. With funding from Autism Speaks, the team is also looking at the genetic and environmental influences on brain and behavior development in these high-risk infants.

In their report, the researchers describe using a magnetic resonance imaging technology called diffusion tensor imaging to image the brains of infants at 6 months, 1 year and 2 years of age. This allowed them to create three-dimensional pictures showing changes in each infant’s “white matter” over time. White matter represents the part of the brain that is particularly rich in the nerve fibers that form major information pathways between different brain regions.

Compared with 64 infants who did not go on to develop ASD, the 28 infants who did develop the disorder showed, on average, very different white matter development for 12 of the 15 major brain pathways studied. Differences were strongest at 6 months and at 2 years, with affected infants showing less change over time. The persistent differences may suggest blunted development of white matter during early infancy, when the brain is making and strengthening vital connections, Piven says.

“These results offer promise that we may one day be able to identify infants at risk for autism before the behavioral symptoms are present,” says study co-author Geri Dawson, Ph.D., Autism Speaks chief science officer. “The goal,” she adds, “is to intervene as early as possible to prevent or reduce the onset of disabling symptoms.” One promising area of follow-up research is to identify the specific genetic and biological mechanisms behind the observed differences in brain development.

For more perspective, please see the related blog post by Geri Dawson. Explore more of the studies we are funding with the Autism Speaks grant search