Volumetric and Voxel-Based Morphometry Findings in Autism Subjects With and Without Macrocephaly

• DOI: 10.1080/87565641003696817
• Publication Date: 2010-05-05T09:09:59Z
• Authors: Erin D. Bigler; Tracy J. Abildskov; Jo Ann Petrie; Michael Johnson; Nicholas Lange; Jonathan Chipman; Jeffrey Lu; William McMahon; Janet E. Lainhart
• Keywords: Intelligence Tests; Male; Brain Diseases; Brain Mapping; Adolescent; Developmental Disabilities; Brain; Functional Laterality; Young Adult; 03 medical and health sciences; Diffusion Magnetic Resonance Imaging; 0302 clinical medicine; Multivariate Analysis; Linear Models; Humans; Body Weights and Measures; Female; Autistic Disorder; Child

This study sought to replicate Herbert et al. (2003a), which found increased overall white matter (WM) volume in subjects with autism, even after controlling for head size differences. To avoid the possibility that greater WM volume in autism is merely an epiphenomena of macrocephaly overrepresentation associated with the disorder, the current study included control subjects with benign macrocephaly. The control group also included subjects with a reading disability to insure cognitive heterogeneity. WM volume in autism was significantly larger, even when controlling for brain volume, rate of macrocephaly, and other demographic variables. Autism and controls differed little on whole-brain WM voxel-based morphometry (VBM) analyses suggesting that the overall increase in WM volume was non-localized. Autism subjects exhibited a differential pattern of IQ relationships with brain volumetry findings from controls. Current theories of brain overgrowth and their importance in the development of autism are discussed in the context of these findings.