Prefrontal and Occipital Asymmetry and Volume in Children and Adolescents with Autism Spectrum Disorder (P03.129)

Abstract

Objective: The purpose of this study was to examine prefrontal and occipital asymmetry (brain torque) in children and adolescents with autism spectrum disorder (ASD) compared to typically developing controls. A secondary aim was to examine age-related changes in gray and white matter volumes. Background ASD is a neurodevelopmental disorder, involving deficits in social functions and language and communication, accompanied by repetitive behaviors or restricted or unusual interests. Typical brain torque (R>L prefrontal, L>R occipital) has been shown to develop in utero and is thought to be related to functional laterality. Previous studies in ASD have demonstrated differences in cerebral asymmetry and early cortical development. Design/Methods: This study included 24 right-handed boys with ASD and 27 typically developing right-handed boys, 7-15 years old. Prefrontal and occipital volumes were measured on individual MRIs. Asymmetry quotients were calculated and volumes were examined proportional to total hemisphere volume. Correlations between age and gray and white matter volumes were examined in each group. Results: Most individuals had the expected rightward prefrontal and leftward occipital asymmetry, with no group differences in the number of individuals with these asymmetries or in the degree of asymmetry. We found a trend for larger prefrontal (gray+white) volume in the ASD group relative to controls (p=.053). Increasing age was associated with increases in total white matter (left r=.467, p=.014; right r=.410, p=.033) and left prefrontal white matter volume (r=.414, p=.032) in the typically developing, but not ASD group (p>.05). Conclusions: Our findings suggest that differences in brain torque may not underlie reported reduced functional lateralization in ASD, but studies directly examining this relationship need to be completed. Our results also provide further support for aberrant cortical development in ASD, likely occurring after birth and continuing into adolescence, with prefrontal regions being disproportionally affected. Supported by: National Institute on Deafness and Other Communication Disorders U19 DC 03610 (HTF). Disclosure: Dr. Knaus has nothing to disclose. Dr. Tager-Flusberg has nothing to disclose. Dr. Mock has nothing to disclose. Dr. Dauterive has nothing to disclose. Dr. Foundas has nothing to disclose.