There is currently no consensus on the neuroanatomical brain correlates of autism. This lack of consensus is likely due to the fact that available studies on the structural brain basis of autism differ in diagnostic criteria, age and IQ of participants with autism, and have utilized different brain imaging methods.
The aim of the present study was to investigate the neuroanatomical correlates of high-functioning autism by novel cortical thickness methods in well-defined and closely matched subject groups.
Subjects were 19 participants diagnosed with autism via ADI-R and ADOS (mean age 23.4 years, 6.6 SD, mean global IQ 100.4, 12.4 SD), and 15 controls who had no neurological history, and were closely matched to participants with autism in age and global IQ. All participants were right-handed.
T1-weighted MR images were obtained for all subjects on a 3 Tesla scanner. Cortical thickness maps were derived from these MRI data for each subject as described elsewhere (Lerch and Evans, 2005) and between-group statistical analyses were then performed. Ethical approval for the present work was obtained in accordance with the National Institute of Health guidelines.
Region specific differences in cortical thickness between groups were found in predicted distributed cortical areas such as brain areas implicated in auditory (right Heschl’s gyrus) and visual perception (middle occipital gyrus), and in social cognition (bilateral frontal cortex, right cingulate gyrus).
Our findings demonstrate that cortical thickness is a viable method to detect differences in brain regions implicated in the perceptual (Mottron et al, 2006), social and emotional (Schultz et al, 2005) domains, and thus in the important processing domains in which autistic demonstrate atypicalities.