Investigation of Neuroanatomical Differences
Between Autism and Asperger Syndrome

Lotspeich L, Kwon H, Schumann C, Fryer S, Goodlin-Jones B, Buonocore M, Lammer C, Amaral D, Reiss A
Stanford University Department of Child and Adolescent Psychiatry, Stanford, CA and MIND Institute, Department of Psychiatry, University of California, Davis

Abstract: Arch Gen Psychiatry 61:291-299 2004

Findings

Autism and Asperger syndrome (AS) have overlapping behavioral symptoms and unknown causes. Previous brain imaging studies with autistic individuals have been difficult to replicate and understand because of differences in subjects between sites as well as differences in brain scanning procedures and image processing methods.
To better understand these differences, this study was conducted to determine differences in brain scans between low-functioning autism (LFA), high-functioning autism (HFA), and Asperger syndrome , and to determine differences between two different scanning sites used in this study. At both Stanford and UC Davis sites, subjects with LFA (13 boys), HFA (18 boys), AS (21 boys), and control subjects (21 boys) were given brain scans (magnetic resonance imaging, or MRI) to assess differences in brain anatomy. Subjects ranged from 7.9-17.9 years of age.
Dr. Lotspeich and her colleagues found brain (cerebral) gray matter volumes were enlarged in HFA and LFA compared with controls; however, in AS, brain grey matter volumes were intermediate between HFA and controls. In HFA (not AS), there was a negative correlation between cerebral gray matter volume and performance IQ (greater volumes were associated with lower IQs). There were no significant differences in white matter volumes in the groups. In AS (not HFA), there was a positive correlation between white matter volume and performance IQ (greater volumes were associated with higher IQs). The two study sites showed differences in neuroimaging results.

Conclusions

The differences in cerebral gray tissue volumes between HFA and LFA groups (but not AS) and controls suggests that AS is on the mild side of the autism spectrum. However, initial brain-IQ correlations show differences between HFA and AS, indicating these two disorders may be different during brain development, as seen by patterns of multiple measurements. In general, increases in grey matter in autism is likely due to abnormalities during brain development of these individuals. In addition, the lack of replication between previous autism MRI studies could be due to differences between the two sites in MRI systems and subjects’ age and IQ.