Temporal lobe dysfunction in childhood autism: A PET study

Objective: The nature of the underlying brain dysfunction of childhood auti sm, a life-long severe developmental disorder, is not well understood. Alth ough researchers using functional brain imaging have attempted to contribut e to this debate, previous studies have failed to report consistent localiz ed neocortical brain dysfunction. The authors reasoned that early methods m ay have been insensitive to such dysfunction, which may now be detectable w ith improved technology. Method: To test this hypothesis, regional cerebral blood flow was measured with positron emission tomography (PET) in 21 children with primary autism and in 10 nonautistic children with idiopathic mental retardation. Autistic and comparison groups were similar in average age and developmental quotie nts. The authors first searched for focal brain dysfunction in the autistic group by using a voxel-based whole brain analysis and then assessed the se nsitivity of the method to detect the abnormality in individual children. A n extension study was then performed in an additional group of 12 autistic children. Results: The first autistic group had a highly significant hypoperfusion in both temporal lobes centered in associative auditory and adjacent multimod al cortex, which was detected in 76% of autistic children. Virtually identi cal results were found in the second autistic group in the extension study. Conclusions: PET and voxel-based image analysis revealed a localized dysfun ction of the temporal lobes in school-aged children with idiopathic autism. Further studies will clarify the relationships between these temporal abno rmalities and the perceptive, cognitive, and emotional developmental abnorm alities characteristic of this disorder.