According to a study published online February 17, at AJP in Advance, a section of the website of the American Journal of Psychiatry, researchers at the University of North Carolina at Chapel Hill have discovered considerable differences in brain development at age six months in high-risk infants who develop autism, than high-risk infants who do not develop the condition.
Jason J. Wolff, Ph.D, lead researcher of the study and a postdoctoral fellow at UNC's Carolina Institute for Developmental Disabilities (CIDD), explained:
"It's a promising finding. At this point, it's a preliminary albeit great first step towards thinking about developing a biomarker for risk in advance of our current ability to diagnose autism."
According to results from the study, autism develops in infancy over time, not suddenly in young children. Wolff said this raises the possibility "that we may be able to interrupt that process with targeted intervention."
Senior researcher of the study is Joseph Piven, M.D., director of the CIDD.
Results from the study are the most recent from the current Infant Brian Imagine Study (IBIS) Network. The network is headquartered at UNC and funded by the National Institutes of Health.
In 2007, Piven received an NIH Autism Centers of Excellence (ACE) program network award for the IBIS Network. ACE networks involves researchers from different locations across the country, who collaborate on a single research question.
The team enrolled 92 infants considered high-risk for autism to participate in the study. All participants have older siblings with autism. At six months, all participants underwent diffusion tensor imaging (a type of magnetic resonance imaging [MRI]), as well as behavioral evaluations at 24 months. In addition, the majority of infants underwent further brain imaging scans at either 12 or 24 months or both.
The researchers found that 28 infants (30%) met criteria for autism spectrum disorders at 24 months, while 70% (64 infants) did not. In addition, fractional anisotropy (FA) revealed that white matter fiber tract development - pathways that link brain regions - differed between the two groups. FA measures white matter development and organization, based on the movement of water molecules through brain tissue.
After analyzing 15 individual fiber tracts, the researchers found considerable differences in FA trajectories in 12 of the 15 tracts between infants who developed autism and infants who did not develop the condition. At six months, infants who later developed autism had raised FA, but then experienced slower change over time. Compared to infants without autism, those with the condition had lower FA values at 24 months of age.
"This evidence, which implicates multiple fiber pathways, suggests that autism is a whole-brain phenomenon not isolated to any particular brain region."
Study co-authors with UNC affiliations include Wolff, Piven, Hongbin Gu,PhD; Guido Gerig,PhD; Jed T. Elison, PhD; Martin Styner, PhD; Geraldine Dawson, PhD and Heather C. Hazlett, PhD. Other institutions and organizations that took part in the study include the University of Utah, Washington University in St. Louis, University of Washington, McGill University, Children's Hospital of Philadelphia and the University of Alberta.
In addition to funding from the NIH, the IBIS Network receives support from Autism Speaks and the Simons Foundation Autism Research Initiative.
Written by Grace Rattue