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.

Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New Background Cognitive decline after cardiac surgery occurs frequently and persists in a significant proportion of patients. Preclinical studies and human trials suggest that intravenous lidocaine may confer protection in the setting of neurologic injury. It was hypothesized that lidocaine administration would reduce cognitive decline after cardiac surgery compared to placebo. Methods After institutional review board approval, 478 patients undergoing cardiac surgery were enrolled into this multicenter, prospective, randomized, double-blinded, placebo-controlled, parallel group trial. Subjects were randomized to lidocaine 1 mg/kg bolus after the induction of anesthesia followed by a continuous infusion (48 μg · kg−1 · min−1 for the first hour, 24 μg · kg−1 · min−1 for the second hour, and 10 μg · kg−1 · min−1 for the next 46 h) or saline with identical volume and rate changes to preserve blinding. Cognitive function was assessed preoperatively and at 6 weeks and 1 yr postoperatively using a standard neurocognitive test battery. The primary outcome was change in cognitive function between baseline and 6 weeks postoperatively, adjusting for age, years of education, baseline cognition, race, and procedure type. Results Among the 420 allocated subjects who returned for 6-week follow-up (lidocaine: N = 211; placebo: N = 209), there was no difference in the continuous cognitive score change (adjusted mean difference [95% CI], 0.02 (−0.05, 0.08); P = 0.626). Cognitive deficit (greater than 1 SD decline in at least one cognitive domain) at 6 weeks occurred in 41% (87 of 211) in the lidocaine group versus 40% (83 of 209) in the placebo group (adjusted odds ratio [95% CI], 0.94 [0.63, 1.41]; P = 0.766). There were no differences in any quality of life outcomes between treatment groups. At the 1-yr follow-up, there continued to be no difference in cognitive score change, cognitive deficit, or quality of life. Conclusions Intravenous lidocaine administered during and after cardiac surgery did not reduce postoperative cognitive decline at 6 weeks.

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 5 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 5 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 3 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;

Background Amyloid deposition is a potential contributor to postoperative cognitive dysfunction. The authors hypothesized that 6-week global cortical amyloid burden, determined by 18F-florbetapir positron emission tomography, would be greater in those patients manifesting cognitive dysfunction at 6 weeks postoperatively. Methods Amyloid deposition was evaluated in cardiac surgical patients at 6 weeks (n = 40) and 1 yr (n = 12); neurocognitive function was assessed at baseline (n = 40), 6 weeks (n = 37), 1 yr (n = 13), and 3 yr (n = 9). The association of 6-week amyloid deposition with cognitive dysfunction was assessed by multivariable regression, accounting for age, years of education, and baseline cognition. Differences between the surgical cohort with cognitive deficit and the Alzheimer’s Disease Neuroimaging Initiative cohorts (normal and early/late mild cognitive impairment) was assessed, adjusting for age, education, and apolipoprotein E4 genotype. Results The authors found that 6-week abnormal global cortical amyloid deposition was not associated with cognitive dysfunction (13 of 37, 35%) at 6 weeks postoperatively (median standard uptake value ratio [interquartile range]: cognitive dysfunction 0.92 [0.89 to 1.07] vs. 0.98 [0.93 to 1.05]; P = 0.455). In post hoc analyses, global cortical amyloid was also not associated with cognitive dysfunction at 1 or 3 yr postoperatively. Amyloid deposition at 6 weeks in the surgical cohort was not different from that in normal Alzheimer’s Disease Neuroimaging Initiative subjects, but increased over 1 yr in many areas at a rate greater than in controls. Conclusions In this study, postoperative cognitive dysfunction was not associated with 6-week cortical amyloid deposition. The relationship between cognitive dysfunction and regional amyloid burden and the rate of postoperative amyloid deposition merit further investigation.

The 2 strongest predictors of consent were male gender and comfort; predictors of refusal were protocol type that requires additional testing, greater concern about blood sampling and study risks, and lower overall patient comfort with the study. These patient and study characteristics may inform modification of the consent process for clinical research studies and facilitate the development of more accurate enrollment projections and strategies.

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