A Preliminary Longitudinal Magnetic Resonance Imaging Study of Brain Volume and Cortical Thickness in Autism

Background Autism is a developmental neurobiologic disorder associated with structural and functional abnormalities in several brain regions including the cerebral cortex. This longitudinal study examined developmental changes in brain volume and cortical thickness (CT) using magnetic resonance imaging (MRI) in children with autism. Methods MRI scans and behavioral measures were obtained at baseline and after a 30-month interval in a sample of male subjects with autism ( n = 18) and healthy age-, and sex-matched control subjects ( n = 16) between ages 8 and 12 years at baseline. Results No differences in brain volumes were observed between the autism and control subjects at baseline or follow-up. However, differences in total gray matter volumes were observed over time with significantly greater decreases in the autism group compared with control subjects. Differences in CT were observed over time with greater decreases in the autism group compared with control subjects in several brain regions including the frontal lobe. When accounting for multiple comparisons, differences between the two groups became nonsignificant except for changes in occipital CT. Furthermore, associations were observed between several clinical features and changes in CT with greater thinning of the cortex being correlated with more severe symptomatology. Conclusions Findings from this study provide preliminary evidence for age-related changes in gray matter volume and CT in children with autism that are associated with symptoms severity. Future longitudinal studies of larger sample sizes are needed to evaluate developmental changes and examine the relationships between structural abnormalities and clinical expressions of the disorder.