WEDNESDAY, May 4 (HealthDay News) -- Children with autism spectrum disorder (ASD) have generalized cerebral cortical enlargement with disproportionate enlargement in temporal lobe white matter, according to a study published in the May issue of the Archives of General Psychiatry.
Heather Cody Hazlett, Ph.D., from the University of North Carolina in Chapel Hill, and colleagues investigated early growth trajectories in cerebral gray and white matter volume and cortical thickness in 38 children with ASD and 21 control children. The children underwent magnetic resonance imaging (MRI) and behavior assessment at approximately 2 years of age, and MRIs were repeated 24 months later when children were 4 to 5 years old.
The investigators found that children with ASD had generalized cerebral cortical enlargement at both 2 and 4 to 5 years of age. There was no increase in cerebral cortical growth rate in children with ASD with growth rates across multiple brain regions and tissue compartments similar to that seen in the controls. Children with ASD exhibited no cerebellar differences. The ASD group had disproportionate enlargement in temporal lobe white matter, after controlling for total brain volume. The two groups showed no significant differences in cortical thickness, but compared to controls, the ASD group showed an increase in estimated surface area for all cortical regions measured (temporal, frontal, and parieto-occipital lobes).
"In this longitudinal MRI study of very early brain volume development in individuals with ASD, we observed generalized cerebral cortical enlargement in children with ASD at both 2 and 4 to 5 years of age," the authors write.