title: Abnormal asymmetry of white matter integrity in schizophrenia revealed by voxelwise diffusion tensor imaging.
abstract: A number of magnetic resonance imaging (MRI) studies have revealed morphological cortical asymmetry in the normal human brain, and reduction or inversion of such hemispheric asymmetry has been reported in schizophrenia. On the other hand, diffusion tensor imaging (DTI) studies have reported inconsistent findings concerning abnormal asymmetry of white matter integrity in schizophrenia. Our aim was to confirm whether there is reduced or inverted asymmetry of white matter integrity in the whole brain in schizophrenia. For this study, 26 right-handed schizophrenia patients, and 32 matched healthy control subjects were investigated. Voxelwise analysis of DTI data was performed using the tract-based spatial statistics. The fractional anisotropy (FA) images were normalized and projected onto the symmetrical white matter skeleton, and the laterality index (LI) of FA, determined by 2 × (left - right)/(left + right), was calculated. The results reveal that schizophrenia patients and healthy controls showed similar patterns of overall FA asymmetries. In the group comparison, patients showed significant reduction of LI in the external capsule (EC), and posterior limb of the internal capsule (PLIC). The EC cluster revealed increased rightward asymmetry, and the PLIC cluster showed reduced leftward asymmetry. Rightward-shift of FA in the EC cluster correlated with negative symptom severity. Considering that the EC cluster includes the uncinate and inferior occipitofrontal fasciculi, which have connections to the orbitofrontal cortex, abnormal asymmetry of white matter integrity in schizophrenia may play a crucial role in the pathogenesis of schizophrenia, through the altered connectivity to the orbitofrontal cortex.
authors: Department of Neuropsychiatry, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawaharacho, Kyoto 606-8507, Japan. miyata10@kuhp.kyoto-u.ac.jp
authors: Jun
authors: J
authors: Miyata
authors: Akihiko
authors: A
authors: Sasamoto
authors: Katja
authors: K
authors: Koelkebeck
authors: Kazuyuki
authors: K
authors: Hirao
authors: Keita
authors: K
authors: Ueda
authors: Ryosaku
authors: R
authors: Kawada
authors: Shinsuke
authors: S
authors: Fujimoto
authors: Yusuke
authors: Y
authors: Tanaka
authors: Manabu
authors: M
authors: Kubota
authors: Hidenao
authors: H
authors: Fukuyama
authors: Nobukatsu
authors: N
authors: Sawamoto
authors: Hidehiko
authors: H
authors: Takahashi
authors: Toshiya
authors: T
authors: Murai
mesh_terms: D000328:Adult; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D012559:Schizophrenia / Q000473:pathology*