Unfavourable left-right asymmetries of the brain and autism: a question of methodology.

Thirty-six patients with infantile autism and various neurological disorders underwent computerized tomographic (CT) scanning of the brain. All CT scans were assessed blindly and independently by a diagnostic radiologist. Two techniques modified from two previous studies were used for measuring parieto-occipital asymmetry. The frequency of reversed asymmetry in autistic patients was the same as that in patients with various neurological disorders, and there was no significant association between reversed asymmetry and delayed language development. The study does not support the concept that unfavourable morphological asymmetries of the brain near the posterior language zone may contribute to the difficulties autistic children experience in acquiring language. Methodological difficulties and the design of new studies are discussed.