Total Brain Volume and Corpus Callosum Size in Medication-Naïve Adolescents and Young Adults with Autism Spectrum Disorder
Received 14 October 2008; received in revised form 10 February 2009; accepted 6 March 2009. published online 04 May 2009.
Background
Increased total brain volume (TBV) has been reported for children with autism spectrum disorder (ASD) but studies in older ASD subjects have been contradictory. Similarly, studies of corpus callosum (CC) area in ASD differ with regard to inclusion criteria, age, and IQ.
Methods
In the present study, TBV, gray matter (GM), and white matter (WM) volume as well as midsagittal CC area were compared between 15 medication-naïve, high-functioning adolescent and young adult ASD subjects and 15 healthy control individuals, and correlations with visuomotor coordination and imitation abilities were explored. In addition, computational surface-based methods were implemented to encode callosal thickness at high spatial resolution.
Results
Total brain volume, GM, and WM were increased and CC area was decreased in ASD subjects, a finding that was predominantly due to ASD subjects with lower IQ. Positive correlations of IQ with volume measures were observed only in control subjects. Autism spectrum disorder subjects showed reduced thickness in the posterior part of the CC. White matter volume showed a trend for negative correlation with dynamic balance and imitation abilities across groups.
Conclusions
This study replicates previous structural magnetic resonance imaging (MRI) findings in ASD, emphasizes the role of IQ differences, and adds some evidence for functional implications of structural findings.
aDepartment of Child and Adolescent Psychiatry, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
bDepartment of Child and Adolescent Psychiatry, Saarland University Hospital, Homburg, Germany
cDepartment of Neuroradiology, Saarland University Hospital, Homburg, Germany
dLaboratory of NeuroImaging, Department of Neurology, UCLA School of Medicine, Los Angeles, California
eDepartment of Psychiatry and Psychotherapy, Interdisciplinary Center for Clinical Research (IZKF), University of Münster, Münster, Germany
Address correspondence to Christine M. Freitag, M.D., M.A., Department of Child and Adolescent Psychiatry, Johann Wolfgang Goethe-Universität, Deutschordenstraße 50, 60528 Frankfurt am Main, Germany
ABSTRACT