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BOC01
October 24, 2015
10/24/2015 1:10:00 PM - 10/24/2015 3:10:00 PM
Room Upper 4
Resting-State Brain Functional Connectivity Changes Associated With Cognitive Outcomes Following Cardiac Surgery
Jeffrey N. Browndyke, Ph.D., Todd Harshbarger, Ph.D., Tiffany Bisanar, R.N., John H. Alexander, M.D., Yanne Toulgoat-Dubois, B.A., Miles Berger, M.D.,Ph.D., William D. White, M.P.H., Mark F. Newman, M.D., Joseph P. Mathew, M.D.
Duke University Medical Center, Durham, North Carolina , United States
Disclosures:  J.N. Browndyke: None. T. Harshbarger: None. T. Bisanar: None. J.H. Alexander: None. Y. Toulgoat-Dubois: None. M. Berger: None. W.D. White: None. M.F. Newman:
Introduction: Postoperative cognitive dysfunction (POCD) is a post-acute cognitive syndrome observed in some patients after surgical procedures. POCD is present in about a third of patients at 6 weeks after cardiac surgery and is associated with a reduced quality of life.(1,2) Despite notable incidence rates and POCD being a possible risk factor for late-life dementia,(3) little is known about the functional neuroanatomical substrates underlying the syndrome. In the first study of its kind, we present an investigation of the relationship between POCD and functional brain organization in a group of cardiac surgical patients and a well-matched group of non-surgical cardiac controls.

Methods: Following Institutional Review Board approval, patients undergoing cardiac surgery with cardiopulmonary bypass and non-surgical patients with cardiovascular disease (control group) were prospectively enrolled. Participants were administered a battery of standardized neuropsychological tests tapping multiple cognitive domains and functions at baseline and 6 weeks. The magnitude of global cognitive postoperative change from baseline was expressed as the mean of reliable change indices (RCI) for all test variables. 3D FSPGR structural and SENSE spiral-in functional imaging data were acquired at 3 Tesla on a GE MR750 MRI magnet at baseline and 6 weeks. BOLD signal artifacts, linear drift, cardiac/pulse and respiratory signals, signal in white matter and CSF, as well as movement, were excluded from the functional data. Participants ’ global cognitive change score and post-processed resting state fMRI data were entered into a voxel-wise intrinsic connectivity regression model with additional subject-level age and education regressors; cluster p-FWE<0.05 was considered significant.

Results: 12 cardiac surgical patients (1 CABG, 10 Valve, 1 CABG + Valve) and 12 control patients were enrolled. No statistical differences were found in participant demographics [Age 69.7 +/- 7.3 vs 70.4 +/- 7.9; Education (yrs): 15.1 +/- 2.1 vs 15.0 +/- 2.9; Sex (M/F) 11/1 vs 8/4] or baseline cognitive variables. Statistically significant positive relationships were found between regions of postoperative change in intrinsic functional connectivity and cognitive outcomes in the posterior cingulate cortex (pCC) and right superior frontal gyrus (rSFG) regions in the cardiac surgical participants (see Figure). There were no significant regions of associated functional connectivity and cognitive change in the non-surgical controls.

Conclusion: POCD severity in cardiac surgical patients is positively associated with the magnitude of postoperative intrinsic functional connectivity decline in the pCC and rSFG with the most robust relationship being found for the pCC region. Our results reveal the pCC and frontal lobe to be important neuroanatomical regions for future investigations of POCD phenomenology and pathophysiology.

References

1. Newman MF, et al. N Engl J Med. 2001; 344:395-402.

2. Phillips-Bute B, et al. Psychosom Med. 2006; 68:369-375.

3. Arora SS, et al. in Int J Neurosci. 2014; 124:236-242.

Figure Legend: A.1 & B.1 - pCC and rSFG postoperative voxel-wise intrinsic functional connectivity change. A.2 & B.2 - Relationship between pCC connectivity and cognition and rSFG connectivity and cognition in surgical patients and controls.
Figure 1

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