Antonio Hardan

Evidence for Anatomical Alterations in the Corpus Callosum in Autism Spectrum Disorders

Frazier T, Barnea-Goraly N, Hardan A. European Psychiatric Review. 2010: 3 29-33

Recent imaging studies have suggested reductions in the size of the corpus callosum (CC) in autism spectrum disorders (ASD). This paper reviews evidence for morphometric and structural alterations of the CC and presents future directions for understanding the role of the CC in ASD. Meta-analytic evidence from mid-sagittal area investigations and findings from recent volumetric studies support the existence of CC size reduction in ASD, particularly in anterior regions. These reductions are associated with structural alterations, as measured by other imaging modalities such as diffusion tensor imaging, and appear to be due to early-life hypoplasia, rather than atrophy. Early life CC abnormalities are part of a larger pattern of abnormal brain development that results in alterations of short- and long-distance brain connectivity. Future studies are needed to clarify the heterogeneity of CC abnormalities within the broad spectrum of ASD and examine the specificity of CC alterations to autism in comparison with other neuropsychiatric disorders. Longitudinal multi-modal imaging studies will be essential for identifying the abnormal developmental patterns of the CC and their contribution to the pathophysiology of ASD.