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Research paper
Disrupted small world topology and modular organisation of functional networks in late-life depression with and without amnestic mild cognitive impairment
  1. Wenjun Li1,2,
  2. B Douglas Ward2,
  3. Xiaolin Liu2,
  4. Gang Chen2,
  5. Jennifer L Jones3,
  6. Piero G Antuono3,
  7. Shi-Jiang Li1,2,
  8. Joseph S Goveas1
  1. 1Department of Psychiatry and Behavioral Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
  2. 2Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
  3. 3Department of Neurology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
  1. Correspondence to Dr Joseph S Goveas, Department of Psychiatry and Behavioral Medicine, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA; jgoveas{at}mcw.edu

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.

Aims 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.

  • DEPRESSION
  • COGNITIVE NEUROPSYCHOLOGY
  • MRI
  • MEMORY

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