"This study further strengthens the biological basis of the language problems seen in both autism and SLI," says Gordon Harris, PhD, director of the Radiology Computer-Aided Diagnostics Laboratory (RAD CADx Lab) in the MGH Department of Radiology, the paper's senior author.
Autism is a serious developmental disorder characterized by a lack of normal social interaction, language abnormalities and repetitive, ritualistic behavior. In previous imaging studies of autistic boys, Harris's group identified an alteration in language-associated areas of the brain. In most right-handed individuals, what is referred to as Broca's area is larger on the left side of the brain. The 2002 MGH study showed that most right-handed autistic boys had a reversal of this pattern, with the larger area on the right side.
Other researchers have reported similar reversal of the normal brain asymmetry in people with SLI, a condition of delayed language development without other impairments, and in other language disorders. A genetic connection may exist between SLI and autism, since relatives of those with one disorder have an increased risk of developing the other. Because their earlier study did not distinguish between autistic boys with and without language problems, the MGH team looked more closely at whether the altered brain asymmetry might be related to language difficulties specifically, or to a
Contact: Sue McGreevey
Massachusetts General Hospital