title: Disrupted brain connectivity networks in drug-naive, first-episode major depressive disorder.
abstract: BACKGROUND
  Neuroimaging studies have shown that major depressive disorder (MDD) is accompanied by structural and functional abnormalities in specific brain regions and connections; yet, little is known about alterations of the topological organization of whole-brain networks in MDD patients.
  
  
  METHODS
  Thirty drug-naive, first-episode MDD patients and 63 healthy control subjects underwent a resting-state functional magnetic resonance imaging scan. The whole-brain functional networks were constructed by thresholding partial correlation matrices of 90 brain regions, and their topological properties (e.g., small-world, efficiency, and nodal centrality) were analyzed using graph theory-based approaches. Nonparametric permutation tests were further used for group comparisons of topological metrics.
  
  
  RESULTS
  Both the MDD and control groups showed small-world architecture in brain functional networks, suggesting a balance between functional segregation and integration. However, compared with control subjects, the MDD patients showed altered quantitative values in the global properties, characterized by lower path length and higher global efficiency, implying a shift toward randomization in their brain networks. The MDD patients exhibited increased nodal centralities, predominately in the caudate nucleus and default-mode regions, including the hippocampus, inferior parietal, medial frontal, and parietal regions, and reduced nodal centralities in the occipital, frontal (orbital part), and temporal regions. The altered nodal centralities in the left hippocampus and the left caudate nucleus were correlated with disease duration and severity.
  
  
  CONCLUSIONS
  These results suggest that depressive disorder is associated with disruptions in the topological organization of functional brain networks and that this disruption may contribute to disturbances in mood and cognition in MDD patients.
authors.affiliation: Huaxi Magnetic Resonance Research Center, Department of Radiology, Center for Medical Imaging, West China Hospital of Sichuan University, Chengdu, China.
authors.forename: Junran
authors.initials: J
authors.lastname: Zhang
authors.forename: Jinhui
authors.initials: J
authors.lastname: Wang
authors.forename: Qizhu
authors.initials: Q
authors.lastname: Wu
authors.forename: Weihong
authors.initials: W
authors.lastname: Kuang
authors.forename: Xiaoqi
authors.initials: X
authors.lastname: Huang
authors.forename: Yong
authors.initials: Y
authors.lastname: He
authors.forename: Qiyong
authors.initials: Q
authors.lastname: Gong
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D001921:Brain / Q000098:blood supply / Q000503:physiopathology*; D001931:Brain Mapping; D003865:Major Depressive Disorder / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000098:blood supply / Q000503:physiopathology; D009434:Neural Pathways / Q000098:blood supply / Q000503:physiopathology; D010100:Oxygen / Q000097:blood; D013223:Statistics as Topic; D055815:Young Adult
chemical_list: D010100:Oxygen