Mapping corpus callosum morphology in twin pairs discordant for bipolar disorder.

TitleMapping corpus callosum morphology in twin pairs discordant for bipolar disorder.
Publication TypeJournal Article
Year of Publication2011
AuthorsBearden, CE, van Erp TGM, Dutton RA, Boyle C, Madsen S, Luders E, Kieseppa T, Tuulio-Henriksson A, Huttunen M, Partonen T, Kaprio J, Lönnqvist J, Thompson PM, Cannon TD
JournalCerebral cortex (New York, N.Y. : 1991)
Volume21
Issue10
Pagination2415-24
Date Published2011 Oct
ISSN1460-2199
KeywordsAdult, Bipolar disorder, Brain Mapping, Cohort Studies, Corpus Callosum, Diseases in Twins, Female, Humans, Male, Middle Aged, Registries
Abstract

Callosal volume reduction has been observed in patients with bipolar disorder, but whether these deficits reflect genetic vulnerability to the illness remains unresolved. Here, we used computational methods to map corpus callosum abnormalities in a population-based sample of twin pairs discordant for bipolar disorder. Twenty-one probands with bipolar I disorder (mean age 44.4 ± 7.5 years; 48% female), 19 of their non-bipolar co-twins, and 34 demographically matched control twin individuals underwent magnetic resonance imaging. Three-dimensional callosal surface models were created to visualize its morphologic variability and to localize group differences. Neurocognitive correlates of callosal area differences were additionally investigated in a subsample of study participants. Bipolar (BPI) probands, but not their co-twins, showed significant callosal thinning and area reduction, most pronounced in the genu and splenium, relative to healthy twins. Altered callosal curvature was additionally observed in BPI probands. In bipolar probands and co-twins, genu and splenium midsagittal areas were significantly correlated with verbal processing speed and response inhibition. These findings suggest that aberrant connections between cortical regions--possibly reflecting decreased myelination of white matter tracts--may be involved in bipolar pathophysiology. However, findings of callosal thinning appear to be disease related, rather than reflecting genetic vulnerability to bipolar illness.

DOI10.1111/j.1751-7893.2008.00088.x
Alternate JournalCereb. Cortex