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

Brain Structural and Functional Changes Associated With Postoperative Neurocognitive Disorders: Research Update

Postoperative neurocognitive disorders (PNDs) are frequent and serious perioperative complications in the elderly, and are associated with increased morbidity and mortality, length of hospital stay, and need for long-term care. At present, the pathogenesis of PND is not completely clear, and there are various risk factors including surgical trauma and stress mediating systemic inflammation towards neuroinflammation development which causes brain structural and functional changes namely PND. For elderly patients, perioperative neurological monitoring may provide insights into brain function status. Monitoring may also help clinicians identify potential risks which would ultimately allow timely and effective intervention for better perioperative safety and prognosis for elderly patients. In this review, we summarize the risk factors and potential mechanisms of PND, and discuss preliminary evidence regarding application of electroencephalography, functional near-infrared spectroscopy, functional magnetic resonance, and positron emission tomography imaging in monitoring the central nervous system during the postoperative period.

Cardiac surgery with valve replacement temporarily disrupts the hippocampal memory network

BACKGROUND

Systemic inflammation after heart valve replacement surgery commonly results in complications including cognitive impairment. This study was designed to investigate whether valvular heart disease itself and inflammation after valve replacement surgery affects cognition and the related functional connectivity (FC) of the hippocampal memory network.

METHODS

Forty-three patients with valvular heart disease were screened for recruitment and assessed with cognition function tests, blood inflammatory cytokine measurements, and functional magnetic resonance imaging scans before surgery and on postoperative day 7 and 30. Age- and sex-matched healthy controls (n=30) were recruited for comparison. The brain FC networks using the hippocampus as a seed were analysed. Bivariate correlation and structural equation model analyses were carried out to investigate the association between altered FC, memory, and inflammation.

RESULTS

Thirty-five patients and 29 healthy controls completed the study, and their data were finally analysed and reported. Compared with healthy controls, the surgery group had increased FC in the bilateral precuneus and middle cingulate and paracingulate gyri before surgery. They exhibited impaired memory, increased plasma concentrations of proinflammatory cytokines, and decreased hippocampal FC at postoperative day 7. At 30 days after surgery, the FC abnormalities seen before surgery and at postoperative day 7 were restored to the level comparable with the healthy controls. High systemic inflammation was significantly associated with worse memory and lower FC in the hippocampal memory network.

CONCLUSIONS

Valve replacement surgery temporarily disrupts the hippocampal memory network with transient associated memory decline.

CLINICAL TRIAL REGISTRATION

ChiCTR2300069614.

Predilection for Perplexion: Preoperative microstructural damage is linked to postoperative delirium

Postoperative delirium is the most common postsurgical complication in older adults and is associated with an increased risk of long-term cognitive decline and Alzheimer's disease (AD) and related dementias (ADRD). However, the neurological basis of this increased risk-whether postoperative delirium unmasks latent preoperative pathology or leads to AD-relevant pathology after perioperative brain injury-remains unclear. Recent advancements in neuroimaging techniques now enable the detection of subtle brain features or damage that may underlie clinical symptoms. Among these, Neurite Orientation Dispersion and Density Imaging (NODDI) can help identify microstructural brain damage, even in the absence of visible macro-anatomical abnormalities. To investigate potential brain microstructural abnormalities associated with postoperative delirium and cognitive function, we analyzed pre- and post-operative diffusion MRI data from 111 patients aged ≥60 years who underwent non-cardiac/non-intracranial surgery. Specifically, we investigated preoperative variation in diffusion metrics within the posterior cingulate cortex (PCC), a region in which prior work has identified glucose metabolism alterations in the delirious brain, and a key region in the early accumulation of amyloid beta (Aβ) in preclinical AD. We also examined the relationship of preoperative PCC NODDI abnormalities with preoperative cognitive function. Compared to patients who did not develop postoperative delirium (n=99), we found increased free water (FISO) and neurite density index (NDI) and decreased orientation dispersion index (ODI) in the dorsal PCC before surgery among those who later developed postoperative delirium (n=12). These FISO differences before surgery remained present at six weeks postoperatively, while these NDI and ODI differences did not. Preoperative dorsal PCC NDI and ODI values were also positively associated with preoperative attention/concentration performance, independent of age, education level, and global brain atrophy. Yet, these diffusion metrics were not correlated with cerebrospinal fluid Aβ positivity or levels. These results suggest that preoperative latent brain abnormalities within the dorsal PCC may underlie susceptibility to postoperative delirium, independent of AD-related (i.e., Aβ) neuropathology. Furthermore, these preoperative microstructural differences in the dorsal PCC were linked to preoperative deficits in attention/concentration, a core feature of postoperative delirium. Our findings highlight microstructural vulnerability within the PCC, a key region of the default mode network, as a neuroanatomic locus that can help explain the link between preoperative attention/concentration deficits and increased postoperative delirium risk among vulnerable older surgical patients.

Cognitive and Cerebrospinal Fluid Alzheimer's Disease-related Biomarker Trajectories in Older Surgical Patients and Matched Nonsurgical Controls

BACKGROUND

Anesthesia and/or surgery accelerate Alzheimer's disease pathology and cause memory deficits in animal models, yet there is a lack of prospective data comparing cerebrospinal fluid (CSF) Alzheimer's disease-related biomarker and cognitive trajectories in older adults who underwent surgery versus those who have not. Thus, the objective here was to better understand whether anesthesia and/or surgery contribute to cognitive decline or an acceleration of Alzheimer's disease-related pathology in older adults.

METHODS

The authors enrolled 140 patients 60 yr or older undergoing major nonneurologic surgery and 51 nonsurgical controls via strata-based matching on age, sex, and years of education. CSF amyloid β (Aβ) 42, tau, and p-tau-181p levels and cognitive function were measured before and after surgery, and at the same time intervals in controls.

RESULTS

The groups were well matched on 25 of 31 baseline characteristics. There was no effect of group or interaction of group by time for baseline to 24-hr or 6-week postoperative changes in CSF Aβ, tau, or p-tau levels, or tau/Aβ or p-tau/Aβ ratios (Bonferroni P > 0.05 for all) and no difference between groups in these CSF markers at 1 yr (P > 0.05 for all). Nonsurgical controls did not differ from surgical patients in baseline cognition (mean difference, 0.19 [95% CI, -0.06 to 0.43]; P = 0.132), yet had greater cognitive decline than the surgical patients 1 yr later (β, -0.31 [95% CI, -0.45 to -0.17]; P < 0.001) even when controlling for baseline differences between groups. However, there was no difference between nonsurgical and surgical groups in 1-yr postoperative cognitive change in models that used imputation or inverse probability weighting for cognitive data to account for loss to follow up.

CONCLUSIONS

During a 1-yr time period, as compared to matched nonsurgical controls, the study found no evidence that older patients who underwent anesthesia and noncardiac, nonneurologic surgery had accelerated CSF Alzheimer's disease-related biomarker (tau, p-tau, and Aβ) changes or greater cognitive decline.

EDITOR’S PERSPECTIVE

Associations between Alzheimer's disease biomarkers and postoperative delirium or cognitive dysfunction: A meta-analysis and trial sequential analysis of prospective clinical trials

BACKGROUND

The relationship between Alzheimer's disease biomarkers and postoperative complications, such as postoperative delirium (POD) and postoperative cognitive dysfunction (POCD), remains a subject of ongoing debate.

OBJECTIVE

This meta-analysis aimed to determine whether there is an association between perioperative Alzheimer's disease biomarkers and postoperative complications.

DESIGN

We conducted a meta-analysis of observational clinical studies that explored the correlation between Alzheimer's disease biomarkers and POD or POCD in patients who have undergone surgery, following PRISMA guidelines. The protocol was previously published (INPLASY: INPLASY202350001).

DATA SOURCES

A comprehensive search was conducted across PubMed, Embase, Web of Science, and Cochrane databases until March 2023.

ELIGIBILITY CRITERIA

Surgical patients aged at least 18 years, studies focusing on POD or POCD, research involving Alzheimer's disease biomarkers, including Aβ or tau in blood or cerebrospinal fluid (CSF), and availability of the full text.

RESULTS

Our meta-analysis included 15 studies: six focusing on POD and nine on POCD. The findings revealed a negative correlation between preoperative CSF β-amyloid 42 (Aβ42) levels and the onset of POD [mean difference -86.1, 95% confidence interval (CI), -114.15 to -58.05, I2 : 47%]; this association was strongly supported by trial sequential analysis (TSA). A similar negative correlation was discerned between preoperative CSF Aβ42 levels and the incidence of POCD (-165.01, 95% CI, -261.48 to -68.53, I2 : 95%). The TSA also provided robust evidence for this finding; however, the evidence remains insufficient to confirm a relationship between other Alzheimer's disease biomarkers [β-amyloid 40 (Aβ40), total tau (T-tau), phosphorylated tau (P-tau), and Aβ42/T-tau ratio] and POD or POCD.

CONCLUSION

The study results indicate a negative correlation between preoperative CSF Aβ42 levels and the occurrence of both POD and POCD. Future investigations are warranted to identify the predictive cutoff value of preoperative CSF Aβ42 for POD and POCD.

Cognitive Effects of Body Temperature During Hypothermic Circulatory Arrest Trial (GOT ICE): A Randomized Clinical Trial Comparing Outcomes After Aortic Arch Surgery

BACKGROUND

Deep hypothermia has been the standard for hypothermic circulatory arrest (HCA) during aortic arch surgery. However, centers worldwide have shifted toward lesser hypothermia with antegrade cerebral perfusion. This has been supported by retrospective data, but there has yet to be a multicenter, prospective randomized study comparing deep versus moderate hypothermia during HCA.

METHODS

This was a randomized single-blind trial (GOT ICE [Cognitive Effects of Body Temperature During Hypothermic Circulatory Arrest]) of patients undergoing arch surgery with HCA plus antegrade cerebral perfusion at 4 US referral aortic centers (August 2016-December 2021). Patients were randomized to 1 of 3 hypothermia groups: DP, deep (≤20.0 °C); LM, low-moderate (20.1-24.0 °C); and HM, high-moderate (24.1-28.0 °C). The primary outcome was composite global cognitive change score between baseline and 4 weeks postoperatively. Analysis followed the intention-to-treat principle to evaluate if: (1) LM noninferior to DP on global cognitive change score; (2) DP superior to HM. The secondary outcomes were domain-specific cognitive change scores, neuroimaging findings, quality of life, and adverse events.

RESULTS

A total of 308 patients consented; 282 met inclusion and were randomized. A total of 273 completed surgery, and 251 completed the 4-week follow-up (DP, 85 [34%]; LM, 80 [34%]; HM, 86 [34%]). Mean global cognitive change score from baseline to 4 weeks in the LM group was noninferior to the DP group; likewise, no significant difference was observed between DP and HM. Noninferiority of LM versus DP, and lack of difference between DP and HM, remained for domain-specific cognitive change scores, except structured verbal memory, with noninferiority of LM versus DP not established and structured verbal memory better preserved in DP versus HM (P = 0.036). There were no significant differences in structural or functional magnetic resonance imaging brain imaging between groups postoperatively. Regardless of temperature, patients who underwent HCA demonstrated significant reductions in cerebral gray matter volume, cortical thickness, and regional brain functional connectivity. Thirty-day in-hospital mortality, major morbidity, and quality of life were not different between groups.

CONCLUSIONS

This randomized multicenter study evaluating arch surgery HCA temperature strategies found low-moderate hypothermia noninferior to traditional deep hypothermia on global cognitive change 4 weeks after surgery, although in secondary analysis, structured verbal memory was better preserved in the deep group. The verbal memory differences in the low- and high-moderate groups and structural and functional connectivity reductions from baseline merit further investigation and suggest opportunities to further optimize brain perfusion during HCA.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02834065.

Different whole-brain functional connectivity correlates of reactive-proactive aggression and callous-unemotional traits in children and adolescents with disruptive behaviors

BACKGROUND

Disruptive behavior in children and adolescents can manifest as reactive aggression and proactive aggression and is modulated by callous-unemotional traits and other comorbidities. Neural correlates of these aggression dimensions or subtypes and comorbid symptoms remain largely unknown. This multi-center study investigated the relationship between resting state functional connectivity (rsFC) and aggression subtypes considering comorbidities.

METHODS

The large sample of children and adolescents aged 8-18 years (n = 207; mean age = 13.30±2.60 years, 150 males) included 118 cases with disruptive behavior (80 with Oppositional Defiant Disorder and/or Conduct Disorder) and 89 controls. Attention-deficit/hyperactivity disorder (ADHD) and anxiety symptom scores were analyzed as covariates when assessing group differences and dimensional aggression effects on hypothesis-free global and local voxel-to-voxel whole-brain rsFC based on functional magnetic resonance imaging at 3 Tesla.

RESULTS

Compared to controls, the cases demonstrated altered rsFC in frontal areas, when anxiety but not ADHD symptoms were controlled for. For cases, reactive and proactive aggression scores were related to global and local rsFC in the central gyrus and precuneus, regions linked to aggression-related impairments. Callous-unemotional trait severity was correlated with ICC in the inferior and middle temporal regions implicated in empathy, emotion, and reward processing. Most observed aggression subtype-specific patterns could only be identified when ADHD and anxiety were controlled for.

CONCLUSIONS

This study clarifies that hypothesis-free brain connectivity measures can disentangle distinct though overlapping dimensions of aggression in youths. Moreover, our results highlight the importance of considering comorbid symptoms to detect aggression-related rsFC alterations in youths.

Inflammation Disrupts the Brain Network of Executive Function after Cardiac Surgery

OBJECTIVE

To investigate postoperative functional connectivity (FC) alterations across impaired cognitive domains and their causal relationships with systemic inflammation.

BACKGROUND

Postoperative cognitive dysfunction commonly occurs after cardiac surgery, and both systemic and neuroinflammation may trigger its development. Whether FC alterations underlying deficits in specific cognitive domains after cardiac surgery are affected by inflammation remains unclear.

METHODS

Seventeen patients, who underwent cardiac valve replacement, completed a neuropsychological test battery and brain MRI scan before surgery and on days 7 and 30 after surgery compared to age-matched healthy controls. Blood samples were taken for tumor necrosis factor-a and interleukin-6 measurements. Seed-to-voxel FC of the left dorsolateral prefrontal cortex (DLPFC) was examined. Bivariate correlation and linear regression models were used to determine the relationships among cognitive function, FC alterations, and cytokines.

RESULTS

Executive function was significantly impaired after cardiac surgery. At day 7 follow-up, the surgical patients, compared to the controls, demonstrated significantly decreased DLPFC FC with the superior parietal lobe and attenuated negative connectivity in the default mode network, including the angular gyrus and posterior cingulate cortex. The left DLPFC enhanced the connectivity in the right DLPFC and posterior cingulate cortex, all of which were related to the increased tumor necrosis factor-a and decreased executive function up to day 7 after cardiac surgery.

CONCLUSIONS

The decreased FC of executive control network and its anticorrelation with the default mode network may contribute to executive function deficits after cardiac surgery. Systemic inflammation may trigger these transient FC changes and executive function impairments.

Regional cerebral hypometabolism on 18F-FDG PET/CT scan in delirium is independent of acute illness and dementia

INTRODUCTION

Delirium is associated with new onset dementia and accelerated cognitive decline; however, its pathophysiology remains unknown. Cerebral glucose metabolism previously seen in delirium may have been attributable to acute illness and/or dementia. We aimed to statistically map cerebral glucose metabolism attributable to delirium.

METHODS

We assessed cerebral glucose metabolism using ¹⁸ F-fluorodeoxyglucose positron emission tomography (FDG-PET) in sick, older patients with and without delirium, all without clinical dementia (N = 20). Strict exclusion criteria were adopted to minimize the effect of established confounders on FDG-PET.

RESULTS

Patients with delirium demonstrated hypometabolism in the bilateral thalami and right superior frontal, right posterior cingulate, right infero-lateral anterior temporal, and left superior parietal cortices. Regional hypometabolism correlated with delirium severity and performance on neuropsychological testing.

DISCUSSION

In patients with acute illness but without clinical dementia, delirium is accompanied by regional cerebral hypometabolism. While some hypometabolic regions may represent preclinical Alzheimer's disease (AD), thalamic hypometabolism is atypical of AD and consistent with the clinical features that are unique to delirium.

Functional MRI Changes in Patients after Thyroidectomy under General Anesthesia

Cognitive changes affecting elderly patients following surgery under anesthesia have drawn significant attention and have been investigated in considerable depth. Resting-state functional magnetic resonance imaging (rs-fMRI) can be used to assess changes in brain functional connectivity (FC) associated with postoperative changes in cognition, a common complication in seniors undergoing surgery. In this study, we recruited 20 patients over 55 of age and scheduled an elective thyroidectomy under general anesthesia to assess perioperative changes in brain FC density (FCD) in patients undergoing thyroidectomy under general anesthesia using rs-fMRI. All 20 patients underwent a series of clinical, quantitative, neurological, and neuropsychological tests and fMRI examinations on the day before surgery (Day 0) and 7 days after surgery (Day 7). The following tests were conducted on all patients: the Minimental State Examination (MMSE), the digit symbol substitution test (DSST), the trail making test (part A), the verbal fluency test, and Warrington's recognition memory test (WRMT). FMRI data were acquired using a 3T MR system; the FCD values were calculated using the REST software package. We used paired t-tests to compare the FCD between Day 7 and Day 0. A value of p < 0.05 was considered to reflect statistical significance. The postoperative FCD was significantly reduced in the supplementary motor area (SMA). Analyses of the percentage changes of errors in the WRMT revealed a significant and negative correlation with the mean percentage change of FCD in the SMA (Spearman's r = −0.54, 95% CI: (-0.80, -0.12), p = 0.014). Postoperative changes in FCD in the SMA may be associated with the perioperative neurocognitive changes in patients undergoing partial thyroidectomy under general anesthesia.

Postoperative changes in cognition and cerebrospinal fluid neurodegenerative disease biomarkers

OBJECTIVE

Numerous investigators have theorized that postoperative changes in Alzheimer's disease neuropathology may underlie postoperative neurocognitive disorders. Thus, we determined the relationship between postoperative changes in cognition and cerebrospinal (CSF) tau, p-tau-181p, or Aβ levels after non-cardiac, non-neurologic surgery in older adults.

METHODS

Participants underwent cognitive testing before and 6 weeks after surgery, and lumbar punctures before, 24 h after, and 6 weeks after surgery. Cognitive scores were combined via factor analysis into an overall cognitive index. In total, 110 patients returned for 6-week postoperative testing and were included in the analysis.

RESULTS

There was no significant change from before to 24 h or 6 weeks following surgery in CSF tau (median [median absolute deviation] change before to 24 h: 0.00 [4.36] pg/mL, p = 0.853; change before to 6 weeks: -1.21 [3.98] pg/mL, p = 0.827). There were also no significant changes in CSF p-tau-181p or Aβ over this period. There was no change in cognitive index (mean [95% CI] 0.040 [-0.018, 0.098], p = 0.175) from before to 6 weeks after surgery, although there were postoperative declines in verbal memory (-0.346 [-0.523, -0.170], p = 0.003) and improvements in executive function (0.394, [0.310, 0.479], p < 0.001). There were no significant correlations between preoperative to 6-week postoperative changes in cognition and CSF tau, p-tau-181p, or Aβ42 changes over this interval (p > 0.05 for each).

INTERPRETATION

Neurocognitive changes after non-cardiac, non-neurologic surgery in the majority of cognitively healthy, community-dwelling older adults are unlikely to be related to postoperative changes in AD neuropathology (as assessed by CSF Aβ, tau or p-tau-181p levels or the p-tau-181p/Aβ or tau/Aβ ratios).

TRIAL REGISTRATION

clinicaltrials.gov (NCT01993836).

Relationship Between Depression/Anxiety and Cognitive Function Before and 6 Weeks After Major Non-Cardiac Surgery in Older Adults

OBJECTIVE

To determine the relationship between affective measures and cognition before and after non-cardiac surgery in older adults.

METHODS

Observational prospective cohort study in 103 surgical patients age ≥ 60 years old. All participants underwent cognitive testing, Center for Epidemiologic Studies-Depression, and State Anxiety Inventory screening before and 6 weeks after surgery. Cognitive test scores were combined by factor analysis into 4 cognitive domains, whose mean was defined as the continuous cognitive index (CCI). Postoperative global cognitive change was defined by CCI change from before to after surgery, with negative CCI change indicating worsened postoperative global cognition and vice versa.

RESULTS

Lower global cognition before surgery was associated with greater baseline depression severity (Spearman's r = -0.30, p = 0.002) and baseline anxiety severity (Spearman's r = -0.25, p = 0.010), and these associations were similar following surgery (r = -0.36, p < 0.001; r = -0.26, p = 0.008, respectively). Neither baseline depression or anxiety severity, nor postoperative changes in depression or anxiety severity, were associated with pre- to postoperative global cognitive change.

CONCLUSIONS

Greater depression and anxiety severity were each associated with poorer cognitive performance both before and after surgery in older adults. Yet, neither baseline depression or anxiety symptoms, nor postoperative change in these symptoms, were associated with postoperative cognitive change.

Perioperative neurocognitive and functional neuroimaging trajectories in older APOE4 carriers compared with non-carriers: secondary analysis of a prospective cohort study

BACKGROUND

Cognitive dysfunction after surgery is a major issue in older adults. Here, we determined the effect of APOE4 on perioperative neurocognitive function in older patients.

METHODS

We enrolled 140 English-speaking patients ≥60 yr old scheduled for noncardiac surgery under general anaesthesia in an observational cohort study, of whom 52 underwent neuroimaging. We measured cognition; Aβ, tau, p-tau levels in CSF; and resting-state intrinsic functional connectivity in six Alzheimer's disease-risk regions before and 6 weeks after surgery.

RESULTS

There were no significant APOE4-related differences in cognition or CSF biomarkers, except APOE4 carriers had lower CSF Aβ levels than non-carriers (preoperative median CSF Aβ [median absolute deviation], APOE4 305 pg ml^-1 [65] vs 378 pg ml^-1 [38], respectively; P=0.001). Controlling for age, APOE4 carriers had significantly greater preoperative functional connectivity than non-carriers between several brain regions implicated in Alzheimer's disease, including between the left posterior cingulate cortex and left angular gyrus (β [95% confidence interval, CI], 0.218 [0.137-0.230]; P_FWE=0.016). APOE4 carriers, but not non-carriers, experienced significant connectivity decreases from before to 6 weeks after surgery between several brain regions including between the left posterior cingulate cortex and left angular gyrus (β [95% CI], -0.196 [-0.256 to -0.136]; P_FWE=0.001). Most preoperative and postoperative functional connectivity differences did not change after controlling for preoperative CSF Aβ levels.

CONCLUSIONS

Postoperative change trajectories for cognition and CSF Aβ, tau or p-tau levels did not differ between community dwelling older APOE4 carriers and non-carriers. APOE4 carriers showed greater preoperative functional connectivity and greater postoperative decreases in functional connectivity in key Alzheimer's disease-risk regions, which occur via Aβ-independent mechanisms.

Abnormally weak functional connections get stronger in chronic stroke patients who benefit from naming therapy

Language recovery in aphasia is likely supported by a network of brain regions, but few studies have investigated treatment-related changes in functional connectivity while controlling for the absence of treatment. We examined functional connectivity in a 38-region picture-naming network in 30 patients with chronic aphasia who did or did not receive naming therapy. Compared to healthy controls, patients had abnormally low connectivity in a subset of connections from the naming network. Linear mixed models showed that the connectivity of abnormal connections increased significantly in patients who benefited from therapy, but not in those who did not benefit from or receive therapy. Changes in responders were specific to abnormal connections and did not extend to the larger network. Thus, successful naming therapy was associated with increased connectivity in connections that were abnormal prior to treatment. The potential to strengthen such connections may be a prerequisite for a successful treatment response.

Cerebrospinal Fluid Proteome Changes in Older Non-Cardiac Surgical Patients with Postoperative Cognitive Dysfunction

Background:

Postoperative cognitive dysfunction (POCD), a syndrome of cognitive deficits occurring 1–12 months after surgery primarily in older patients, is associated with poor postoperative outcomes. POCD is hypothesized to result from neuroinflammation; however, the pathways involved remain unclear. Unbiased proteomic analyses have been used to identify neuroinflammatory pathways in multiple neurologic diseases and syndromes but have not yet been applied to POCD.

Objective:

To utilize unbiased mass spectrometry-based proteomics to identify potential neuroinflammatory pathways underlying POCD.

Methods:

Unbiased LC-MS/MS proteomics was performed on immunodepleted cerebrospinal fluid (CSF) samples obtained before, 24 hours after, and 6 weeks after major non-cardiac surgery in older adults who did (n = 8) or did not develop POCD (n = 6). Linear mixed models were used to select peptides and proteins with intensity differences for pathway analysis.

Results:

Mass spectrometry quantified 8,258 peptides from 1,222 proteins in > 50%of patient samples at all three time points. Twelve peptides from 11 proteins showed differences in expression over time between patients with versus without

POCD (q < 0.05), including proteins previously implicated in neurodegenerative disease pathophysiology. Additionally, 283 peptides from 182 proteins were identified with trend-level differences (q < 0.25) in expression over time between these groups. Among these, pathway analysis revealed that 50 were from 17 proteins mapping to complement and coagulation pathways (q = 2.44^*10^–13).

Conclusion:

These data demonstrate the feasibility of performing unbiased mass spectrometry on perioperative CSF samples to identify pathways associated with POCD. Additionally, they provide hypothesis-generating evidence for CSF complement and coagulation pathway changes in patients with POCD.

Altered spontaneous brain activity pattern in patients with ophthalmectomy: an resting-state fMRI study

AIM

To use the voxel-wise degree centrality (DC) method to explore the underlying functional network brain-activity in patients with ophthalmectomy.

METHODS

A total of 32 ophthalmic surgery patients (10 women and 22 men), and 32 healthy subjects (10 women and 22 men) highly matched in gender, age, and the same operation method. Everyone experienced a resting-state functional magnetic resonance imaging scan. The spontaneous brain activity could be assessed by DC. Correlation analysis was used to explore the relationships between the average DC signal values and behavior performance in different regions. Receiver operating characteristic (ROC) curve analysis was utilized to differentiate between ophthalmectomy patients and healthy controls (HCs).

RESULTS

Compared with HCs, ophthalmectomy patients had greatly reduced DC values in left lingual gyrus, bilateral lingual lobe, left cingulate gyrus, and increased DC values of left cerebellum posterior lobe, left middle frontal gyrus1, right supramarginal gyrus, left middle frontal gyrus2, right middle frontal gyrus. However, we did not find that there was a correlation between the average DC values from various brain regions and clinical manifestations.

CONCLUSION

Dysfunction may be caused by ophthalmectomy in lots of cerebral areas, which may show the potential pathological mechanism of ophthalmectomy and it is beneficial to clinical diagnosis.

Premorbid Alterations of Spontaneous Brain Activity in Elderly Patients With Early Post-operative Cognitive Dysfunction: A Pilot Resting-State Functional MRI Study

Background: Elderly patients with pre-existing cognitive impairment are susceptible to post-operative cognitive dysfunction (POCD). In this study, we investigated whether there is pre-existing local homogeneity and functional connectivity alteration in the brain before surgery for POCD patients as compared to that in non-POCD patients.

Methods: Eighty elderly patients undergoing major thoracic or abdominal surgeries were recruited. Resting-state functional MRI was scanned at least 1 day before surgery. Neuropsychological tests (NPTs) were performed before surgery and at discharge, respectively. Pre-operative regional homogeneity (ReHo) and resting-state functional connectivity (RSFC) were compared between POCD patients and non-POCD patients, respectively. Partial correlation between NPTs and ReHo or RSFC was analyzed by adjusting for confounding factors.

Results: Significant difference (P < 0.001, Gaussian Random Field (GRF) correction which is a multiple comparisons correction method at cluster level, cluster size > 49) in ReHo between POCD patients and non-POCD patients was detected in right hippocampus/parahippocampus. Pre-operative RSFC between right hippocampus/parahippocampus and right middle/inferior temporal gyrus increased in POCD patients (P < 0.001, GRF correction for multiple comparisons) when compared with that in non-POCD patients.RSFC significantly correlated with composite Z-score (r = 0.46, 95% CI [0.234, 0.767], P = 0.002) or Digit Symbol Substitution Test Z-scores (r = 0.31, 95% CI [0.068, 0.643], P = 0.046) after adjusting for confounding factors.

Conclusions: The results suggest that premorbid alterations of spontaneous brain activity might exist in elderly patients who develop early POCD. The neural mechanism by which patients with pre-operative abnormal spontaneous activity are susceptible to POCD requires further study.

State of the clinical science of perioperative brain health: report from the American Society of Anesthesiologists Brain Health Initiative Summit 2018

Cognitive recovery after anaesthesia and surgery is a concern for older adults, their families, and caregivers. Reports of patients who were 'never the same' prompted a scientific inquiry into the nature of what patients have experienced. In June 2018, the ASA Brain Health Initiative held a summit to discuss the state of the science on perioperative cognition, and to create an implementation plan for patients and providers leveraging the current evidence. This group included representatives from the AARP (formerly the American Association of Retired Persons), American College of Surgeons, American Heart Association, and Alzheimer's Association Perioperative Cognition and Delirium Professional Interest Area. This paper summarises the state of the relevant clinical science, including risk factors, identification and diagnosis, prognosis, disparities, outcomes, and treatment of perioperative neurocognitive disorders. Finally, we discuss gaps in current knowledge with suggestions for future directions and opportunities for clinical and translational projects.

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.