Abnormal Corpus Callosum Integrity in Bipolar Disorder: A Diffusion Tensor Imaging Study

Abstract

Objective-Abnormalities in the anterior interhemispheric connections provided by the corpus callosum (CC) have long been implicated in bipolar disorder (BD). In this study, we used complementary diffusion tensor imaging (DTI) methods to study the structural integrity of the CC and localization of potential abnormalities in BD. Methods-Subjects included 33 participants with BD and 40 healthy comparison participants.Fractional anisotropy (FA) measures were compared between groups using region of interest (ROI) methods to investigate the anterior, middle and posterior CC and voxel-based methods to further localize abnormalities.Results-In ROI-based analyses, FA was significantly decreased in the anterior and middle CC in the BD group (P<0.05). Voxel-based analyses similarly localized group differences to the genu, rostral body and anterior midbody of CC (P<0.05, corrected).Conclusion-The findings demonstrate abnormalities in the structural integrity of the anterior CC in BD which may contribute to altered inter-hemispheric connectivity in this disorder.The anterior corpus callosum (CC) has been implicated in bipolar disorder (BD) since at least 1903 when Starr described symptoms detected after anterior CC lesions similar to those of BD, such as "undue excitement, causeless laughter, unusual crying, great depression and a lack of harmony between the association of ideas and the state of feeling which they should awaken" (1). An early magnetic resonance imaging (MRI) study of cerebral morphology in BD detected mid-sagittal CC area decreases (2). Subsequent structural MRI studies provided further evidence for CC white matter abnormalities in BD including in volume, signal intensity Corresponding Author: Fei Wang, M.D., Ph.D. Department of Psychiatry, Yale University School of Medicine, Mailing Address: 300 George Street, Suite 901, New Haven, CT 06511, Phone: 203-785-6180, Fax: 203-737-2513, email: fei.wang@yale.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. and structural integrity (3-5), although reports varied in the CC subregions studied and regional differences detected. In this study, complementary diffusion tensor imaging (DTI) region of interest (ROI) and voxel-based methods were used to study the structural integrity of CC white matter in BD and assess the regional localization of differences. Anterior CC reductions in FA in BD were anticipated. Methods ParticipantsThe Structured Clinical Interview for DSM-IV Axis I Disorders Version 2.0 (SCID) (6) confirmed the presence or absence of Axis I Disorders and mood state at scanning for the 33 BD and 40 healt...

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