Resting‐State Functional Connectivity and Cognition After Major Cardiac Surgery in Older Adults without Preoperative Cognitive Impairment: Preliminary Findings

Abstract

Background/Objectives Resting-state functional magnetic resonance imaging was used to examine for changes in intrinsic functional brain connectivity associated with postoperative changes in cognition; a common complication in seniors undergoing major surgery. Design Objective cognitive testing and functional brain imaging were prospectively performed at preoperative baseline and 6-weeks after surgery, and at the same time intervals in non-surgical controls. Setting Academic medical center. Participants 12 senior patients undergoing cardiac surgery and 12 non-surgical senior controls with a history of coronary artery disease; both groups without cognitive impairment at preoperative baseline (MMSE > 27). Measurements Differences in resting-state functional connectivity (RSFC) and global cognitive change relationships were assessed using a voxel-wise intrinsic connectivity method, controlled for demographic factors and pre- and perioperative cerebral white matter disease volume. Analyses were corrected for multiple comparisons, p-FDR <0.01. Results Global cognitive change after cardiac surgery was significantly associated with intrinsic RSFC changes in regions of the posterior cingulate cortex (PCC) and right superior frontal gyrus (rSFG); anatomical and functional locations of the brain's default mode network (DMN). No statistically significant relationships were found between global cognitive change and RSFC change in the non-surgical controls. Conclusion Clinicians have long known that some older patients develop postoperative cognitive dysfunction (POCD) after anesthesia and surgery, yet the neurobiological correlates of POCD are not well defined. Our results suggest that altered resting state functional connectivity within specific DMN regions is positively correlated with global cognitive change 6-weeks after cardiac surgery, suggesting that DMN activity and connectivity could be important diagnostic markers of POCD and/or intervention targets for potential POCD treatment efforts.

Impact of Total Knee Arthroplasty with General Anesthesia on Brain Networks: Cognitive Efficiency and Ventricular Volume Predict Functional Connectivity Decline in Older Adults

“…These investigators report significant positive correlates between pre to postoperative DMN change and six-week postoperative decline in a global cognitive index score [15]. Although this needs replication and investigation with a larger sample size, it appears acute RS-fMRI connectivity decline (particularly DMN) has clinical relevance and that DNM activity could be an important prognostic marker for intervention.…”

“…Although RSNs have been investigated relative to age-related and neurological disorders [12], the application of RSNs to surgical studies are still in an early stage. Researchers to date investigated the utility of RS-fMRI in neurosurgery, particularly for tumor resection, (e.g., [13, 14]) and cardiac surgery (e.g., [15]) patients. Browndyke and colleagues [15] demonstrated preliminary findings of a link between RSN connectivity and postoperative cognitive dysfunction, however they did not assess network connectivity in the acute postoperative stage or risk factors for this decline.…”

“…Researchers to date investigated the utility of RS-fMRI in neurosurgery, particularly for tumor resection, (e.g., [13, 14]) and cardiac surgery (e.g., [15]) patients. Browndyke and colleagues [15] demonstrated preliminary findings of a link between RSN connectivity and postoperative cognitive dysfunction, however they did not assess network connectivity in the acute postoperative stage or risk factors for this decline. There are also resting state functional MRI network connectivity changes during active anesthesia [16–20].…”

Dopamine Adaptations as a Common Pathway for Neurocognitive Impairment in Diabetes and Obesity: A Neuropsychological Perspective

“…For example, patients with T2D exhibit reduced activity in the default mode network (Musen et al, 2012), which has been associated with a wide range of neurological conditions and cognitive impairments (Browndyke et al, 2017; Contreras et al, 2017; Jockwitz et al, 2017; von Rhein et al, 2017) but BMI, which was higher in T2D, was not accounted for. Similarly, the putative confound of glucose intolerance is often not considered when examining the relationship between obesity and cognition.…”

Postoperative cognitive dysfunction and mortality following lung transplantation

“…9,10 In addition, preliminary studies among patients undergoing cardiac surgery suggest that brain structures critical for intact executive functioning and working memory are often impacted following surgery, 34,35 with inefficiencies in areas associated with default mode network functioning associating highly with behavioral performance. 36 We have previously demonstrated that POCD likely results both from individual vulnerabilities 37 as well as operative characteristics, 38 suggesting that there may be multiple avenues from which interventions can be designed to protect neurocognition in an increasingly older patient population. Neuroimaging data could therefore provide important insights into both the nature (e.g.…”