Decreased Callosal Thickness in Attention-Deficit/Hyperactivity Disorder

Luders, Eileen; Narr, Katherine L.; Hamilton, Liberty S.; Phillips, Owen R.; Thompson, Paul M.; Valle, Jessica S.; Del'Homme, Melissa; Strickland, Tony; McCracken, James T.; Toga, Arthur W.; Levitt, Jennifer G.

doi:10.1016/j.biopsych.2008.08.027

« Previous Next »Biological Psychiatry
Volume 65, Issue 1 , Pages 84-88, 1 January 2009

Decreased Callosal Thickness in Attention-Deficit/Hyperactivity Disorder

Eileen Luders
- Laboratory of Neuro Imaging, Department of Neurology; University of California—at Los Angeles School of Medicine, California
Katherine L. Narr
- Laboratory of Neuro Imaging, Department of Neurology; University of California—at Los Angeles School of Medicine, California
Liberty S. Hamilton
- Laboratory of Neuro Imaging, Department of Neurology; University of California—at Los Angeles School of Medicine, California
Owen R. Phillips
- Laboratory of Neuro Imaging, Department of Neurology; University of California—at Los Angeles School of Medicine, California
Paul M. Thompson
- Laboratory of Neuro Imaging, Department of Neurology; University of California—at Los Angeles School of Medicine, California
Jessica S. Valle
- Argosy University—Orange County, Santa Ana, California
Melissa Del'Homme
- Departments of Psychiatry and Neurology, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California—Los Angeles, California
Tony Strickland
- Department of Neurology, David Geffen School of Medicine at University of California—Los Angeles, California
James T. McCracken
- Departments of Psychiatry and Neurology, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California—Los Angeles, California
Arthur W. Toga
- Laboratory of Neuro Imaging, Department of Neurology; University of California—at Los Angeles School of Medicine, California
- Address reprint requests to Arthur W. Toga, Ph.D., Laboratory of Neuro Imaging, Department of Neurology, UCLA School of Medicine, 635 Charles Young Drive South, Suite 225, Los Angeles, CA 90095-7334
Jennifer G. Levitt
- Departments of Psychiatry and Neurology, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California—Los Angeles, California

Received 26 March 2008; received in revised form 22 August 2008; accepted 25 August 2008. published online 09 October 2008.

Background

Neuroimaging studies of attention-deficit/hyperactivity disorder (ADHD) have revealed structural abnormalities in the brains of affected individuals. One of the most replicated alterations is a significantly smaller corpus callosum (CC), for which conflicting reports exist with respect to the affected callosal segments.

Methods

We applied novel surface-based geometrical modeling methods to establish the presence, direction, and exact location of callosal alterations in ADHD at high spatial resolution. For this purpose, we calculated the thickness of the CC at 100 equidistant midsagittal points in an age-matched male sample of 19 individuals with ADHD and 19 typically developing control subjects.

Results

In close agreement with many prior observations, the CC was shown to be significantly thinner in ADHD subjects in anterior and, particularly, posterior callosal sections. Covarying for intelligence did not significantly alter the observed ADHD effects. However, group differences were no longer present in anterior sections when covarying for brain volume and after excluding ADHD subjects comorbid for oppositional defiant disorder.

Conclusions

Decreased callosal thickness may be associated with fewer fibers or a decrease in the myelination of fibers connecting the parietal and prefrontal cortices. This might affect interhemispheric communication channels that are necessary to sustain attention or motor control, thus contributing to symptoms of hyperactivity and impulsivity, or inattention, observed in ADHD. Future studies are necessary to determine whether callosal abnormalities reflect maturational delays or persist into adulthood.

Key Words: Corpus callosum, isthmus, MRI, ODD, splenium