title: Disrupted structural connectivity network in treatment-naive depression.
abstract: BACKGROUND
  Neuroimaging studies suggest that treatment-naive depression (TD) is characterized by abnormal functional connectivity between specific brain regions. However, the question surrounding the structural basis of functional aberrations in TD patients still remains.
  
  
  METHODS
  In the present study, diffusion tensor imaging tractography was employed to construct structural connectivity networks in 22 early adult-onset, first-episode TD patients and 19 healthy controls (HC). Graph theory and network-based statistic (NBS) were then employed to investigate systematically the alteration of whole brain structural topological organization and structural connectivity in TD patients.
  
  
  RESULTS
  Graph theoretical analysis revealed that, compared with HC, TD patients exhibited altered structural topological measures, including decreased shortest path length, normalized clustering coefficient, normalized shortest path length, and small-worldness, as well as increased global and local efficiency. NBS results further revealed that TD patients showed two altered structural sub-networks. One sub-network mainly involved connections between the right orbitofrontal cortex (OFC) and the right insula, putamen, caudate, hippocampus, fusiform gyrus, inferior temporal gyrus and lingual gyrus. The other sub-network mainly included connections between the left OFC and the left gyrus rectus, insula, putamen, caudate, thalamus, pallidum and middle occipital gyrus.
  
  
  CONCLUSIONS
  The findings suggest that TD patients exhibit a disruption in the topological organization of structural brain networks. The altered orbitofrontal connectivity may particularly contribute to the manifestation of symptoms in TD patients. The abnormalities may facilitate understanding of the functional disturbances of mood and cognition in the disease.
authors.affiliation: Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054, PR China.
authors.forename: Zhiliang
authors.initials: Z
authors.lastname: Long
authors.affiliation: Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054, PR China.
authors.forename: Xujun
authors.initials: X
authors.lastname: Duan
authors.affiliation: Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054, PR China.
authors.forename: Yifeng
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054, PR China.
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
authors.affiliation: Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054, PR China.
authors.forename: Ling
authors.initials: L
authors.lastname: Zeng
authors.affiliation: Mental Health Institute, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, PR China. Electronic address: zhaojingpingcsu@163.com.
authors.forename: Jing-Ping
authors.initials: JP
authors.lastname: Zhao
authors.affiliation: Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054, PR China. Electronic address: chenhf@uestc.edu.cn.
authors.forename: Huafu
authors.initials: H
authors.lastname: Chen
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology*; D003863:Depression / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008959:Models, Neurological; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D009833:Olfactory Pathways / Q000473:pathology*; D019580:Perforant Pathway / Q000473:pathology*; D055815:Young Adult
keywords: Depression; Diffusion tensor imaging tractography; Graph theoretical analysis; Small-worldness; Structural connectivity