title: A treatment-resistant default mode subnetwork in major depression.
abstract: BACKGROUND
  Previous studies have suggested that the default mode network (DMN) plays a central role in the physiopathology of major depressive disorder (MDD). However, the effect of antidepressant treatment on functional connectivity within the DMN has yet to be established. Considering the very high rates of relapse in recovered subjects, we hypothesized that abnormalities in DMN functional connectivity would persist in recovered MDD subjects.
  
  
  METHODS
  Resting state functional magnetic resonance imaging images were collected from 24 MDD patients and 29 healthy control subjects. After 12 weeks of antidepressant treatment, 18 recovered MDD subjects were scanned again. Group independent component analysis was performed to decompose the resting state images into spatially independent components. Default mode subnetworks were identified using a template based on previous studies. Group differences in the ensuing subnetworks were tested using two-sample t tests.
  
  
  RESULTS
  Two spatially independent default mode subnetworks were detected in all subjects: the anterior subnetwork and the posterior subnetwork. Both subnetworks showed increased functional connectivity in pretreatment MDD subjects, relative to control subjects. Differences in the posterior subnetwork were normalized after antidepressant treatment, while abnormal functional connectivity persisted within the anterior subnetwork.
  
  
  CONCLUSIONS
  Our findings suggest a dissociation of the DMN into subnetworks, where persistent abnormal functional connectivity within the anterior subnetwork in recovered MDD subjects may constitute a biomarker of asymptomatic depression and potential for relapse.
authors.affiliation: Department of Automatic Control, College of Mechatronics and Automation, National University of Defense Technology, Changsha, Hunan.
authors.forename: Baojuan
authors.initials: B
authors.lastname: Li
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Friston
authors.forename: Hui
authors.initials: H
authors.lastname: Shen
authors.forename: Lubin
authors.initials: L
authors.lastname: Wang
authors.forename: Ling-Li
authors.initials: LL
authors.lastname: Zeng
authors.forename: Dewen
authors.initials: D
authors.lastname: Hu
mesh_terms: D000328:Adult; D000928:Antidepressive Agents / Q000627:therapeutic use*; D003865:Major Depressive Disorder / Q000188:drug therapy* / Q000503:physiopathology*; D005260:Female; D006179:Gyrus Cinguli / Q000187:drug effects / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000187:drug effects; D010296:Parietal Lobe / Q000187:drug effects / Q000503:physiopathology*; D017397:Prefrontal Cortex / Q000187:drug effects / Q000503:physiopathology*; D012146:Rest / Q000502:physiology*; D055815:Young Adult
chemical_list: D000928:Antidepressive Agents