Exactly why this roughly 5 percent greater brain growth occurs and what it means are not yet clear, scientists said. Indirect evidence suggested that the increased brain growth probably began during the later months of the children's first year of life.
A report on the finding appears in the December issue of the Archives of General Psychiatry. UNC authors are Dr. Heather Cody Hazlett, assistant professor of psychiatry; Dr. Michele Poe, a statistician with the FPG Child Development Institute; Dr. Guido Gerig, professor of computer science; imaging technician Rachel Gimpel Smith; and Drs. John Gilmore and Joseph Piven, professors of psychiatry.
At UNC, Piven, the senior author, directs both its Study to Advance Autism Research and Treatment (STAART) Center and its Neurodevelopmental Disorders Research Center. Duke authors are Drs. James Provenzale and Allison Ross, professor of radiology and associate professor of anesthesiology, respectively.
"Our team conducted brain magnetic resonance imaging scans on 51 autistic and 25 control children at age 2, making it the largest study of two-year-olds with autism," Cody Hazlett said. "Analysis of brain tissue volumes showed significant enlargement, across all regions in both gray and white tissue, in the cerebral cortex of the autistic children.
"While we saw the greatest volume increases in the temporal lobe, an area of the brain involved in language, we concluded that at this age, tissue enlargement is present throughout the cortex."
In the same paper, the team reported on the largest retrospective study of head circumference in autism reported to date, comparing head circumference measurements on 113 autistic children to 190 other young
Contact: David Williamson
University of North Carolina at Chapel Hill