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

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.

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

OBJECTIVES: To look for changes in intrinsic functional brain connectivity associated with postoperative changes in cognition, a common complication in seniors undergoing major surgery, using resting-state functional magnetic resonance imaging. 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 nonsurgical controls. SETTING: Academic medical center. PARTICIPANTS: Older adults undergoing cardiac surgery (n = 12) and nonsurgical older adult controls with a history of coronary artery disease (n = 12); no participants had cognitive impairment at preoperative baseline (Mini-Mental State Examination score >27). MEASUREMENTS: Differences in resting-state functional connectivity (RSFC) and global cognitive change relationships were assessed using a voxel-wise intrinsic connectivity method, controlling for demographic factors and pre- and perioperative cerebral white matter disease volume. Analyses were corrected for multiple comparisons (false discovery rate P < .01). RESULTS: Global cognitive change after cardiac surgery was significantly associated with intrinsic RSFC changes in regions of the posterior cingulate cortex and right superior frontal gyrus-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 nonsurgical controls. CONCLUSION: Clinicians have long known that some older adults develop postoperative cognitive dysfunction (POCD) after anesthesia and surgery, yet the neurobiological correlates of POCD are not well defined. The current results suggest that altered RSFC in 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 or intervention targets for potential POCD treatment efforts.

Determinants of a subject's decision to participate in clinical anesthesia research.

BACKGROUND: A top priority for research studies is to ensure that potential participants receive adequate information to make a truly informed decision. Understanding patient experiences with the recruitment process may identify areas for improvement in the consent process. We examined which factors were associated with the decision to consent in a clinical research study. METHODS: Patients scheduled for elective surgery were asked to complete a questionnaire about the consent process, immediately after being approached to participate in an anesthesia-related research study. Sociodemographic characteristics, preoperative levels of anxiety and depression, medical comorbidities, factors that may affect decision to participate in a research study, and study design features were collected. A multivariable logistic regression model was estimated to identify factors associated with providing consent. Performance of the prediction model was assessed using the receiver operating characteristic curve. Internal validity was assessed by a bootstrap analysis. RESULTS: In all, 282 participants completed the questionnaire. Of those, 179 (63%) had consented to participate in research, and 103 (37%) had declined to participate. In the multivariable logistic regression model, the odds of providing consent were higher for males (odds ratio [OR] [95% confidence interval]=2.49 [1.29-4.79]) and for patients with higher levels of patient comfort (OR=1.84 [1.22-2.78]). The odds of providing consent were lower for protocols that require additional testing (OR=0.15 [0.06-0.39]) and patients with higher levels of concern about blood sampling (OR=0.70 [0.54-0.90]) or worry about study risks (OR=0.72 [0.55-0.95]). Bootstrap analysis revealed a stable model with high internal validity. CONCLUSIONS: 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.