Magnetic resonance imaging volumetric findings in children with Asperger syndrome, nonverbal learning disability, or healthy controls.

Background: The purpose of the present study was to evaluate selected regions of interest in children and adolescents with nonverbal learning disabilities (NVLD), Asperger syndrome (AS), and age-matched healthy controls using magnetic resonance imaging (MRI). It was hypothesized that children with AS would show larger volumes of the amygdala and hippocampal regions than the other groups. It was also hypothesized that both clinical groups would show differences in the caudate and anterior cingulate cortex (ACC).

Method: There were a total of 89 children in the final sample (31 controls, 29 NVLD, 29 AS). Each child completed a MRI scan as well as basic cognitive screening measures. High-resolution T1-weighted MR volumetric images were acquired. The volume of gray matter, white matter, cerebrospinal fluid (CSF), amygdala, hippocampus, and anterior cingulate cortex (ACC) was obtained.

Results: The hypothesis that the AS group would show larger hippocampal and amygdala volumes than the other groups was confirmed. For the AS and NVLD groups, the ACC was found to be significantly smaller than that of the control group.

Conclusions: These results suggest that the ACC and amygdala/hippocampal regions are deficient in children with AS, likely contributing to difficulty with modulating of emotional reactivity.