title: Evidence of a dissociation pattern in resting-state default mode network connectivity in first-episode, treatment-naive major depression patients.
abstract: BACKGROUND
  Imaging studies have shown that major depressive disorder (MDD) is associated with altered activity patterns of the default mode network (DMN). However, the neural correlates of the resting-state DMN and MDD-related pathopsychological characteristics, such as depressive rumination and overgeneral autobiographical memory (OGM) phenomena, still remain unclear.
  
  
  METHODS
  Using independent component analysis, we analyzed resting-state functional magnetic resonance imaging data obtained from 35 first-episode, treatment-naive young adults with MDD and from 35 matched healthy control subjects.
  
  
  RESULTS
  Patients with MDD exhibited higher levels of rumination and OGM than did the control subjects. We observed increased functional connectivity in the anterior medial cortex regions (especially the medial prefrontal cortex and anterior cingulate cortex) and decreased functional connectivity in the posterior medial cortex regions (especially the posterior cingulate cortex/precuneus) in MDD patients compared with control subjects. In the depressed group, the increased functional connectivity in the anterior medial cortex correlated positively with rumination score, while the decreased functional connectivity in the posterior medial cortex correlated negatively with OGM score.
  
  
  CONCLUSIONS
  We report dissociation between anterior and posterior functional connectivity in resting-state DMNs of first-episode, treatment-naive young adults with MDD. Increased functional connectivity in anterior medial regions of the resting-state DMN was associated with rumination, whereas decreased functional connectivity in posterior medial regions was associated with OGM. These results provide new evidence for the importance of the DMN in the pathophysiology of MDD and suggest that abnormal DMN activity may be an MDD trait.
authors.affiliation: Medical Psychological Institute of the Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
authors.forename: Xueling
authors.initials: X
authors.lastname: Zhu
authors.forename: Xiang
authors.initials: X
authors.lastname: Wang
authors.forename: Jin
authors.initials: J
authors.lastname: Xiao
authors.forename: Jian
authors.initials: J
authors.lastname: Liao
authors.forename: Mingtian
authors.initials: M
authors.lastname: Zhong
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Shuqiao
authors.initials: S
authors.lastname: Yao
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003865:Major Depressive Disorder / Q000503:physiopathology* / Q000523:psychology; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods / Q000523:psychology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000523:psychology*; D008297:Male; D061212:Memory, Episodic; D009434:Neural Pathways / Q000503:physiopathology; D012146:Rest / Q000502:physiology*; D013850:Thinking / Q000502:physiology*