Task-related changes in degree centrality and local coherence of the posterior cingulate cortex after major cardiac surgery in older adults

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19 Citations (SciVal)

Abstract

Objectives: Older adults often display postoperative cognitive decline (POCD) after surgery, yet it is unclear to what extent functional connectivity (FC) alterations may underlie these deficits. We examined for postoperative voxel-wise FC changes in response to increased working memory load demands in cardiac surgery patients and nonsurgical controls. Experimental design: Older cardiac surgery patients (n = 25) completed a verbal N-back working memory task during MRI scanning and cognitive testing before and 6 weeks after surgery; nonsurgical controls with cardiac disease (n = 26) underwent these assessments at identical time intervals. We measured postoperative changes in degree centrality, the number of edges attached to a brain node, and local coherence, the temporal homogeneity of regional functional correlations, using voxel-wise graph theory-based FC metrics. Group × time differences were evaluated in these FC metrics associated with increased N-back working memory load (2-back > 1-back), using a two-stage partitioned variance, mixed ANCOVA. Principal observations: Cardiac surgery patients demonstrated postoperative working memory load-related degree centrality increases in the left dorsal posterior cingulate cortex (dPCC; p <.001, cluster p-FWE <.05). The dPCC also showed a postoperative increase in working memory load-associated local coherence (p <.001, cluster p-FWE <.05). dPCC degree centrality and local coherence increases were inversely associated with global cognitive change in surgery patients (p <.01), but not in controls. Conclusions: Cardiac surgery patients showed postoperative increases in working memory load-associated degree centrality and local coherence of the dPCC that were inversely associated with postoperative global cognitive outcomes and independent of perioperative cerebrovascular damage.

Original languageEnglish
Pages (from-to)985-1003
Number of pages19
JournalHuman Brain Mapping
Volume39
Issue number2
DOIs
StatePublished - Feb 2018

Bibliographical note

Funding Information:
The authors thank our research associates: Yanne Toulgoat-Dubois, Rachele Brassard, and Kathryn Odom, and technical staff at the Duke Brain Imaging and Analysis Center (BIAC): Susan Music, Luther Pool, and Natalie Goutkin. They also thank Dr Simon Davis and Mathew Stanley and the members of the Cabeza Lab for their suggestions and comments on this article.

Funding Information:
Research supported, in part, by the National Heart, Lung, and Blood Institute grants HL109971 (JNB & JPM), HL096978 (JPM) and HL108280 (JPM); and National Institute on Aging grants AG042599 (JNB) and AG050918 (MB).

Publisher Copyright:
© 2017 Wiley Periodicals, Inc.

Keywords

  • anesthesia
  • attention
  • brain
  • cognitive dysfunction
  • functional neuroimaging
  • gyrus cingula
  • magnetic resonance imaging
  • memory
  • neuropsychological tests
  • short-term
  • thoracic surgery

ASJC Scopus subject areas

  • Anatomy
  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging
  • Neurology
  • Clinical Neurology

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