Regional cortical volume asymmetry patterns, particularly those associated with language function, in 16 boys with autism (aged 7-11 years) were compared with measures in 15 normal, age- and handedness-matched controls, in an MRI study at the Massachusetts General Hospital, Boston, and other centers. Boys with autism had significant asymmetry reversal in frontal language-related cortex: 27% larger on the right in autism and 17% larger on the left in normal controls. In addition, the posterior temporal fusiform gyrus was more left-sided in autism, whereas adjacent fusiform gyrus and temporooccipital inferior temporal gyrus were more right-sided in autism. Inferior temporal regions are involved in visual social/face processing. Abnormal structural asymmetries in language and face processing cerebral regions may relate to language and social disturbances common in autism. [1]

COMMENT. Both frontal (Broca) and temporal (Wernicke) language-related association cortex regions show a reversal of assymetry in boys with autism compared to controls, but the frontal abnormality is significantly greater. Previous SPECT and PET regional cerebral blood flow studies also show similar asymmetry reversals. MRI studies in normal adults show that the left hemisphere cortical regions are larger in right-handed, left-hemisphere language dominant subjects. In children with specific language impairment (SLI), MRI studies have shown abnormal asymmetries in language cortical measures, similar to those observed in autistic children. Language abnormalities in autism share many features of those in SLI, and these studies support a link between the two disorders.