title: Disrupted small world topology and modular organisation of functional networks in late-life depression with and without amnestic mild cognitive impairment.
abstract: BACKGROUND
  The topological architecture of the whole-brain functional networks in those with and without late-life depression (LLD) and amnestic mild cognitive impairment (aMCI) are unknown.
  
  
  OBJECTIVE
  To investigate the differences in the small-world measures and the modular community structure of the functional networks between patients with LLD and aMCI when occurring alone or in combination and cognitively healthy non-depressed controls.
  
  
  METHODS
  79 elderly participants (LLD (n=23), aMCI (n=18), comorbid LLD and aMCI (n=13), and controls (n=25)) completed neuropsychiatric assessments. Graph theoretical methods were employed on resting-state functional connectivity MRI data.
  
  
  RESULTS
  LLD and aMCI comorbidity was associated with the greatest disruptions in functional integration measures (decreased global efficiency and increased path length); both LLD groups showed abnormal functional segregation (reduced local efficiency). The modular network organisation was most variable in the comorbid group, followed by patients with LLD-only. Decreased mean global, local and nodal efficiency metrics were associated with greater depressive symptom severity but not memory performance.
  
  
  CONCLUSIONS
  Considering the whole brain as a complex network may provide unique insights on the neurobiological underpinnings of LLD with and without cognitive impairment.
authors.affiliation: Department of Psychiatry and Behavioral Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, USA Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Wenjun
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: B
authors.initials: B
authors.lastname: Douglas Ward
authors.affiliation: Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
authors.affiliation: Department of Neurology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Jones
authors.affiliation: Department of Neurology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Piero G
authors.initials: PG
authors.lastname: Antuono
authors.affiliation: Department of Psychiatry and Behavioral Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, USA Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Shi-Jiang
authors.initials: SJ
authors.lastname: Li
authors.affiliation: Department of Psychiatry and Behavioral Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Goveas
mesh_terms: D000368:Aged; D000928:Antidepressive Agents / Q000627:therapeutic use; D001921:Brain / Q000473:pathology; D003072:Cognition Disorders / Q000150:complications / Q000473:pathology* / Q000523:psychology; D060825:Cognitive Dysfunction / Q000150:complications / Q000473:pathology* / Q000523:psychology; D003866:Depressive Disorder / Q000150:complications / Q000473:pathology* / Q000523:psychology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000473:pathology*; D018697:Nootropic Agents / Q000627:therapeutic use; D011569:Psychiatric Status Rating Scales
chemical_list: D000928:Antidepressive Agents; D018697:Nootropic Agents
keywords: COGNITIVE NEUROPSYCHOLOGY; DEPRESSION; MEMORY; MRI