Ratio of β-amyloid protein (Aβ) and Tau predicts the postoperative cognitive dysfunction on patients undergoing total hip/knee replacement surgery

Itaconate alleviates anesthesia/surgery-induced cognitive impairment by activating a Nrf2-dependent anti-neuroinflammation and neurogenesis via gut-brain axis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a common neurological complication of anesthesia and surgery in aging individuals. Neuroinflammation has been identified as a hallmark of POCD. However, safe and effective treatments of POCD are still lacking. Itaconate is an immunoregulatory metabolite derived from the tricarboxylic acid cycle that exerts anti-inflammatory effects by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. In this study, we investigated the effects and underlying mechanism of 4-octyl itaconate (OI), a cell-permeable itaconate derivative, on POCD in aged mice.

METHODS

A POCD animal model was established by performing aseptic laparotomy in 18-month-old male C57BL/6 mice under isoflurane anesthesia while maintaining spontaneous ventilation. OI was intraperitoneally injected into the mice after surgery. Primary microglia and neurons were isolated and treated to lipopolysaccharide (LPS), isoflurane, and OI. Cognitive function, neuroinflammatory responses, as well as levels of gut microbiota and their metabolites were evaluated. To determine the mechanisms underlying the therapeutic effects of OI in POCD, ML385, an antagonist of Nrf2, was administered intraperitoneally. Cognitive function, neuroinflammatory responses, endogenous neurogenesis, neuronal apoptosis, and Nrf2/extracellular signal-related kinases (ERK) signaling pathway were evaluated.

RESULTS

Our findings revealed that OI treatment significantly alleviated anesthesia/surgery-induced cognitive impairment, concomitant with reduced levels of the neuroinflammatory cytokines IL-1β and IL-6, as well as suppressed activation of microglia and astrocytes in the hippocampus. Similarly, OI treatment inhibited the expression of IL-1β and IL-6 in LPS and isoflurane-induced primary microglia in vitro. Intraperitoneal administration of OI led to alterations in the gut microbiota and promoted the production of microbiota-derived metabolites associated with neurogenesis. We further confirmed that OI promoted endogenous neurogenesis and inhibited neuronal apoptosis in the hippocampal dentate gyrus of aged mice. Mechanistically, we observed a decrease in Nrf2 expression in hippocampal neurons both in vitro and in vivo, which was reversed by OI treatment. We found that Nrf2 was required for OI treatment to inhibit neuroinflammation in POCD. The enhanced POCD recovery and promotion of neurogenesis triggered by OI exposure were, at least partially, mediated by the activation of the Nrf2/ERK signaling pathway.

CONCLUSIONS

Our findings demonstrate that OI can attenuate anesthesia/surgery-induced cognitive impairment by stabilizing the gut microbiota and activating Nrf2 signaling to restrict neuroinflammation and promote neurogenesis. Boosting endogenous itaconate or supplementation with exogenous itaconate derivatives may represent novel strategies for the treatment of POCD.

Preoperative cerebrospinal fluid biomarkers may be associated with postoperative delirium in patients undergoing knee/hip arthroplasty: the PNDABLE study

BACKGROUND

In the global aging population, the incidence of postoperative delirium (POD) is increasing. Therefore, finding its effective predictive tools becomes crucial. We aimed to identify potential Cerebrospinal fluid (CSF)biomarkers for POD.

METHODS

A total of 825 patients undergoing knee/hip arthroplasty under combined spinal-epidural anesthesia were selected. The patients were aged 40 to 90 years with American Society of Anesthesiologists physical status I~II. The Mini-Mental State Examination was completed 1 day before the operation. CSF was extracted after successful spinal-epidural combined puncture, and α-synuclein (α-syn), amyloid beta₄₀ (Aβ₄₀), amyloid beta₄₂ (Aβ₄₂), t-Tau, phosphorylated Tau (p-Tau), progranulin (PGRN) and soluble triggering receptor expressed on myeloid cells 2 (sTREM2) in the CSF were measured by enzyme-linked immunosorbent assays (ELISA). The patient's operation time, anesthesia time, intraoperative blood loss and fluid input were also recorded. After the operation, the occurrence rate and severity of POD were determined by the Confusion Assessment Method and the Memorial Delirium Assessment Scale (MDAS), respectively. Patients were categorized into POD group and non-POD group. Logistic regression analysis was performed on the indicators with statistically significant differences, and the area under the ROC curve (AUC) was used to estimate the predictive accuracy of the biomarkers for POD.

RESULTS

A total of 92 patients developed POD and the incidence of POD was 11.15%. The results of the multivariable logistic regression showed that CSF t-Tau (P = 0.004, OR = 1.006, 95%CI 1.002~1.009) and α-syn (P = 0.004, OR = 1.001, 95%CI 1.000~1.001) were positively associated with the occurrence rate of POD, while Aβ₄₂ (P < 0.001, OR = 0.989, 95%CI 0.986~0.993), CSF PGRN (P = 0.002, OR = 0.999, 95%CI 0.999~1.000), Aβ₄₂/ t-Tau (P < 0.001, OR = 0.181, 95%CI 0.102~0.319) and Aβ₄₂/p-Tau (P < 0.001, OR = 0.617, 95%CI 0.526~0.725) were inversely proportional to the occurrence of POD. ROC curve analysis indicated that Aβ₄₂/t-Tau (AUC = 0.823), CSF Aβ₄₂ (AUC = 0.813), Aβ₄₂/p-Tau (AUC = 0.810), α-syn (AUC = 0.644) and PGRN (AUC = 0.638) could predict the occurrence rate of POD. The combination of all these biomarkers showed a greater AUC(0.896) than using any of them alone.

CONCLUSIONS

CSF Aβ₄₂, PGRN, α-syn, Aβ₄₂/t-Tau and Aβ₄₂/p-Tau might be associated with the occurrence rate of POD in patients undergoing knee/hip arthroplasty.

TRIAL REGISTRATION

Clinical Registration No. ChiCTR2000033439.

Mineralocorticoid receptor agonist aldosterone rescues hippocampal neural stem cell proliferation defects and improves postoperative cognitive function in aged mice

OBJECTIVES

Hippocampal neurogenesis is closely related to learning and memory, and hippocampal neurogenesis disorders are involved in the development of many neurodegenerative diseases. Mineralocorticoid receptor (MR) plays a vital role in regulating stress response, neuroendocrine and cognitive functions, and is involved in regulating the integrity and stability of neural networks. However, the potential role of MR in the pathogenesis of postoperative cognitive dysfunction (POCD) is unclear. Therefore, this study evaluated the effect and mechanism of MR activation on postoperative hippocampal neurogenesis and cognitive function in aged mice.

METHODS

18-month-old male Kunming mice were randomly divided into Control group (C group), Surgery group (S group), Surgery+ Aldosterone group (S+Aldo group), Surgery + Wortmannin group (S+Wort group), Surgery + Aldosterone + Wortmannin group (S+Aldo+Wort group). Laparotomy was used to establish an animal model of postoperative cognitive dysfunction. After surgery, mice were intraperitoneally injected with aldosterone (100 ug/kg,150 ug/kg,200 ug/kg) and / or wortmannin (1 mg/kg); One day before the sacrifice, mice were injected intraperitoneally with BrdU (100 mg / kg / time, 3 times in total). Mice were subjected to Morris water maze and field tests at 1, 3, 7, and 14 days after surgery. Immunofluorescence was used to detect the number of BrdU +, Nestin +, BrdU/Nestin + positive cells in the hippocampal dentate gyrus of mice at 1, 3, 7 and 14 days after surgery. Western-blot was used to detect PI3K/Akt/GSK-3β signaling pathway related proteins Akt, p-Akt, GSK-3β, P-GSK-3β expression.

RESULTS

Stress impairs the performance of aged mice in water maze and open field tests, reduces the number of BrdU/Nestin+ cells in the hippocampal dentate gyrus, and inhibits the phosphorylation of Akt and GSK-3β proteins in the hippocampus. Aldosterone treatment promotes P-Akt, P-GSK-3β protein expression and hippocampal neural stem cell proliferation, and improves postoperative cognitive dysfunction. However, wortmannin treatment significantly reversed these effects of aldosterone.

CONCLUSIONS

The mineralocorticoid receptor agonist aldosterone promotes the proliferation of hippocampal neural stem cells and improves cognitive dysfunction in aged mice after surgery, and the mechanism may be related to activation of PI3K/Akt/GSK-3β signaling.

Perioperative probiotics attenuates postoperative cognitive dysfunction in elderly patients undergoing hip or knee arthroplasty: A randomized, double-blind, and placebo-controlled trial

Background

Postoperative cognitive dysfunction (POCD) is a common complication in elderly patients following surgery. The preventive and/or treatment strategies for the incidence remain limited.

Objective

This study aimed to investigate the preventive effect of perioperative probiotic treatment on POCD in elderly patients undergoing hip or knee arthroplasty.

Methods

After obtaining ethical approval and written informed consent, 106 patients (age ≥60 years) were recruited, who scheduled elective hip or knee arthroplasty, from 16 March 2021 to 25 February 2022 for this randomized, double-blind, and placebo-controlled trial. They were randomly assigned with a 1:1 ratio to receive either probiotics or placebo treatment (four capsules, twice/day) from hospital admission until discharge. Cognitive function was assessed with a battery of 11 neuropsychological tests on the admission day and the seventh day after surgery, respectively.

Results

A total of 96 of 106 patients completed the study, and their data were finally analyzed. POCD occurred in 12 (26.7%) of 45 patients in the probiotic group and 29 (56.9%) of 51 patients in the placebo group (relative risk [RR], 0.47 [95% confidence interval [CI], 0.27 to 0.81]; P = 0.003). Among them, mild POCD occurred in 11 (24.4%) in the probiotic group and 24 (47.1%) in the placebo group (RR, 0.52 [95% CI, 0.29 to 0.94]; P = 0.022). No significant difference in severe POCD incidence was found between the two groups (P = 0.209). Compared with the placebo group, the verbal memory domain cognitive function was mainly improved in the probiotic group.

Conclusion

Probiotics may be used perioperatively to prevent POCD development and improve verbal memory performance in elderly patients receiving hip or knee arthroplasty.

Clinical trial registration

www.chictr.org.cn, identifier: ChiCTR2100045620.

Fascia iliaca compartment block can reduce the incidence of early post-operative cognitive impairment in elderly patients with high-risk hip replacement

Objective

In this study, we aimed to observe the effects of ultrasound-guided fascia iliaca compartment block (FICB) combined with hypobaric spinal anesthesia on post-operative pain and cognitive function in elderly patients with high-risk hip replacement.

Methods

A total of 84 elderly patients-aged 65-85 years, with American Society of Anesthesiologists physical status III-IV, and scheduled for hip arthroplasty between September 2021 and May 2022-were selected. One or more organs with moderate to severe impairment were included in all patients. The patients were randomly divided into a hypobaric spinal anesthesia group (group C, control group) and an ultrasound-guided FICB combined with hypobaric spinal anesthesia group (group E, experimental group). Group C was given 3.5 mL of 0.32% ropivacaine hypobaric spinal anesthesia, and group E received ultrasound-guided FICB combined with 3.5 mL of 0.32% ropivacaine hypobaric spinal anesthesia. The patients were compared using the visual analog scale (VAS) for pain, Harris hip function score, and simple Mini-Mental State Examination (MMSE) scale. Blood β-amyloid (Aβ) and neuronal microtubule-associated protein (tau) levels were measured. We compared intraoperative conditions and post-operative complications between the two groups to assess the effects of FICB combined with hypobaric spinal anesthesia on post-operative pain and cognitive function in elderly patients with high-risk hip replacement.

Results

At 1 and 3 days after the operation, patients in group C had significantly higher VAS and lower MMES scores than those in group E. The differences were statistically significant at 1 (P < 0.01) and 3 (P < 0.05) days after the operation. At 1 day after operation, the Harris score of patients in group C was significantly lower than that of patients in group E (P < 0.05). The Aβ and tau levels of patients in group C were significantly higher than those of patients in group E at 1 day after the operation (P < 0.01). The Aβ levels of patients in group C were significantly higher than those of patients in group E at 3 days after the operation (P < 0.05). The intraoperative conditions and post-operative complication rates did not differ significantly between the two groups. At 1 day before and 5 days after the operation, there was no difference in any of the indicators.

Conclusion

By lowering pain and managing Aβ and tau protein concentrations, FICB can successfully lower the incidence of early post-operative cognitive impairment in elderly patients with high-risk hip replacement.

Clinical trial registration

www.chictr.org.cn, identifier: ChiCTR2100051162.

The relationship between mild cognitive impairment and postoperative delirium undergoing total knee arthroplasty: The PNDABLE study

Background

Patients undergoing surgery are at a higher risk of developing postoperative delirium (POD) as a result of anesthesia and surgical procedures. This study examined the association between POD and mild cognitive impairment (MCI) and whether MCI influences POD through the core pathology of POD.

Methods

We enrolled Chinese Han patients undergoing unilateral total knee arthroplasty (aged 50–90, weighing 50–80 kg, and using ASAI-II), combined with epidural anesthesia between October 2020 and June 2021. All the participants were assessed using Winblad's criteria for diagnosing MCI on pre-operation and using the Confusion Assessment Method (CAM) and the Memorial Delirium Assessment Scale (MDAS) postoperative 1–7 days (or before discharge) for diagnosing POD by an anesthesiologist. Cerebrospinal fluid (CSF) biomarkers of POD were measured by enzyme-linked immunosorbent assay (ELISA). To examine the mechanism by which POD pathologies affect cognition, causal mediation analyses were performed.

Results

POD incidence was 20.2%, including 32.5% in the MCI group and 12.4% in the non-mild cognitive impairment (NMCI) group. The MCI and CSF levels of T-tau and P-tau were risk factors, and the CSF levels of Aβ₄₂, Aβ₄₂/ T-tau, and Aβ₄₂/ P-tau were protective factors in POD (p < 0.05). Part of the effects of MCI on cognition can be attributed to amyloid pathology and tau.

Conclusion

MCI may be a reasonably good prognostic factor in POD development. Overall, amyloid pathology and tau protein might partially mediate the influence of MCI on POD.

Clinical trial registration

www.clinicaltrials.gov, identifier: ChiCTR2000033439.

Does propofol definitely improve postoperative cognitive dysfunction?-a review of propofol-related cognitive impairment

Postoperative cognitive dysfunction (POCD) is a common brain function-related complication after surgery. In addition to old age being an independent risk factor, anesthetics are also important predisposing factors. Among them, propofol is the most commonly used intravenous anesthetic in clinical practice. It has a rapid onset, short half-life, and high recovery quality. Many studies report that propofol can attenuate surgery-induced cognitive impairment, however, some other studies reveal that propofol also induces cognitive dysfunction. Therefore, this review summarizes the effects of propofol on the cognition, and discusses possible related mechanisms, which aims to provide some evidence for the follow-up studies.

Is postoperative cognitive decline after cardiac surgery associated with plasma beta amyloid 1-42 levels?

Background

Postoperative cognitive decline following cardiac surgery is one of the frequently reported complications affecting postoperative outcome, characterized by impairment of memory or concentration. The aetiology is considered multifactorial and the research conducted so far has presented contradictory results. The proposed mechanisms to explain the cognitive decline associated with cardiac surgery include the neurotoxic accumulation of β-amyloid (Aβ) proteins similar to Alzheimer's disease. The comparison of coronary artery bypass grafting procedures concerning postoperative cognitive decline and plasmatic Aβ1-42 concentrations has not yet been conducted.

Methods

The research was designed as a controlled clinical study of patients with coronary artery disease undergoing surgical myocardial revascularization with or without the use of a cardiopulmonary bypass machine. All patients completed a battery of neuropsychological tests and plasmatic Aβ1-42 concentrations were collected.

Results

The neuropsychological test results postoperatively were significantly worse in the cardiopulmonary bypass group and the patients had larger shifts in the Aβ1-42 preoperative and postoperative values than the group in which off-pump coronary artery bypass was performed.

Conclusions

The conducted research confirmed the earlier suspected association of plasmatic Aβ1-42 concentration to postoperative cognitive decline and the results further showed that there were less changes and lower concentrations in the off-pump coronary artery bypass group, which correlated to less neurocognitive decline. There is a lot of clinical contribution acquired by this research, not only in everyday decision making and using amyloid proteins as biomarkers, but also in the development and application of non-pharmacological and pharmacological neuroprotective strategies.

Potential Value of Cerebrospinal Fluid Progranulin in the Identification of Postoperative Delirium in Geriatrics Patients Undergoing Knee Replacement: The Perioperative Neurocognitive Disorder and Biomarker LifestylE Study

Objective: The aim of this study was to investigate whether progranulin (PGRN) levels in cerebrospinal fluid (CSF) were associated with postoperative delirium (POD) in geriatric patients undergoing knee replacement.

Method: A total of 600 Han Chinese patients aged 65–90 years and who underwent unilateral total knee arthroplasty were included in the Perioperative Neurocognitive Disorder And Biomarker LifestylE (PNDABLE) study from June 2020 to November 2020. All participants were assessed using the Confusion Assessment Method and the Memorial Delirium Assessment Scale on postoperative days 1–7 (or before discharge) by an anesthesiologist. CSF PGRN and CSF biomarkers of POD were measured by ELISA. We analyzed the risk and protective factors of POD using the multivariate logistic regression, and the associations between CSF PGRN and CSF biomarkers of POD using multiple linear regression. We also explored whether the influence of CSF PGRN on POD was mediated by POD core pathology in linear regression models.

Results: Postoperative delirium incidence was 9.7% (53/545). There were significant differences in preoperative CSF PGRN between patients with POD and non-POD (NPOD). As for CSF biomarkers, CSF Aβ₄₀, T-tau, and P-tau were risk factors for POD, while CSF PGRN, Aβ₄₂, and Aβ₄₂/Aβ₄₀ were protective factors for POD, as shown by the multivariate logistic regression analysis. CSF PGRN was positively associated with CSF Aβ₄₂ and was negatively associated with CSF Aβ₄₀, T-tau, and P-tau in patients with POD. We found that the AUC was 0.795 (95% CI = 0.706, 0.867) for PGRN between POD and NPOD groups. We found the influence of CSF PGRN on POD was mediated by POD core pathology. The effect was considered partial mediation with the proportion of mediation varying from 44.92 to 62.07%.

Conclusion: Cerebrospinal fluid PGRN may be a reasonably good prognostic factor for POD development. Overall, amyloid pathology and tau protein might partially mediate the influence of PGRN on POD.

Clinical Trial Registration:www.clinicaltrials.gov, identifier ChiCTR2000033439.

Potential Value of Serum Lipid in the Identication of Postoperative Delirium Undergoing Knee/Hip Arthroplasty: The Perioperative Neurocognitive Disorder and Biomarker Lifestyle Study

OBJECTIVE

We aimed to investigate the relationship between preoperative lipid level and postoperative delirium (POD) and explore whether lipid's effect on POD is mediated by POD core protein.

METHODS

A total of 635 patients who were planned to undergo knee/hip arthroplasty under combined spinal-epidural anesthesia, regardless of gender, were selected. The patients were aged 40-90 years with American Society of Anesthesiologists physical status I II. The Mini-Mental State Examination (MMSE) was completed 1 day before the operation. Five milliliter elbow venous blood was taken from the patients before anesthesia, and serum levels of total cholesterol (TG), triglyceride (TC), low-density lipoprotein (LDL-C), and high-density lipoprotein (HDL-C) were detected. Cerebrospinal fluid (CSF) was extracted after successful spinal-epidural combined puncture, and amyloid beta₄₀ (Aβ₄₀), amyloid beta₄₂ (Aβ₄₂), total Tau (t-Tau), and phosphorylated Tau (p-Tau) in the CSF were measured by enzyme-linked immunosorbent assays (ELISA). After the operation, the occurrence and severity of POD were assessed using the Confusion Assessment Method and the Memorial Delirium Assessment Scale (MDAS), respectively. Patients were categorized into POD group and NPOD group. Logistic regression was used to analyze the relationship between POD and TC, TG, LDL-C, and HDL-C, and the mediating effect was used to analyze the role of POD core proteins in the relationship between lipid and MDAS. We used the receiver operating characteristic (ROC) and the precision-recall curve (PRC) analysis to assess the ability of TC, TG, LDL-C, and HDL-C ability to predict POD. Finally, we performed a sensitivity analysis to assess the stability of the results.

RESULTS

A total of 562 patients were finally enrolled in this study, and 66 patients developed POD, with an incidence of 11.7%. Logistic regression analysis showed that high concentration of TC (OR = 3.148, 95%CI 1.858∼5.333, P < 0.001), TG (OR = 2.483, 95%CI 1.573∼3.918, P < 0.001), and LDL-C (OR = 2.469, 95%CI 1.310∼4.656, P = 0.005) in serum were risk factors for POD. A high concentration of HDL-C (OR = 0.258, 95%CI 0.112∼0.594, P = 0.001) was a protective factor for POD after adjusted for age, sex, education, and MMSE score. ROC curves showed that HDL-C have the highest sensitivity and specificity in predicting POD. For these four lipid markers, the PRC range from 0.602 to 0.731, respectively. The mediating analysis showed that POD core proteins could partially mediate the relationship between lipid and POD (effect value: 16.19∼91.04%). The results were barely changed in the sensitivity analysis, and the sensitivity analysis has shown that the results were stable.

CONCLUSION

The increase of serum TG, TC, and LDL-C concentration is a risk factor for POD development, while high HDL-C concentration is a protective factor for POD, and the occurrence of POD is caused by hyperlipidemia may be caused by POD core proteins.

CLINICAL TRIAL REGISTRATION

[www.ClinicalTrials.gov], identifier [Chictr200033439].

Drp-1-Dependent Mitochondrial Fragmentation Contributes to Cobalt Chloride-Induced Toxicity in Caenorhabditis elegans

Excess cobalt may lead to metallosis, characterized by sensorineural hearing loss, visual, and cognitive impairment, and peripheral neuropathy. In the present study, we sought to address the molecular mechanisms of cobalt-induced neurotoxicity, using Caenorhabditis elegans as an experimental model. Exposure to cobalt chloride for 2 h significantly decreased the survival rate and lifespan in nematodes. Cobalt chloride exposure led to increased oxidative stress and upregulation of glutathione S-transferase 4. Consistently, its upstream regulator skn-1, a mammalian homolog of the nuclear factor erythroid 2-related factor 2, was activated. Among the mRNAs examined by quantitative real-time polymerase chain reactions, apoptotic activator egl-1, proapoptotic gene ced-9, autophagic (bec-1 and lgg-1), and mitochondrial fission regulator drp-1 were significantly upregulated upon cobalt exposure, concomitant with mitochondrial fragmentation, as determined by confocal microscopy. Moreover, drp-1 inhibition suppressed the cobalt chloride-induced reactive oxygen species generation, growth defects, and reduced mitochondrial fragmentation. Our novel findings suggest that the acute toxicity of cobalt is mediated by mitochondrial fragmentation and drp-1 upregulation.

[Correlation of cerebrospinal fluid amyloid β-protein 42 and neurofilament light protein levels with postoperative neurocognitive dysfunction in elderly patients]

OBJECTIVE

To detect cerebrospinal fluid levels of amyloid beta- protein 42 (Aβ42) and neurofilament light protein (NFL) and explore their correlation with postoperative neurocognitive dysfunction (PNCD) in elderly patients.

OBJECTIVE

A total of 90 elderly patients undergoing hip or knee replacement with joint epidural anesthesia in our Hospital between January, 2017 and December, 2018 were recruited in this study. The levels of Aβ42 and NFL in the cerebrospinal fluid were detected using ELISA. Simple cognitive status assessment scale (MMSE) was used to evaluate the cognitive status of the patients 1 day before and 7 days after the surgery. All the patients underwent neurocognitive function tests, and the z-score method was used to determine the occurrence of PNCD. Spearman rank correlation analysis was used to analyze the correlation of Aβ42 and NFL levels in the cerebrospinal fluid with MMSE scores. Receiver operating characteristic curve (ROC) was used to analyze the predictive value of cerebrospinal fluid Aβ42 and NFL levels for PNCD.

OBJECTIVE

PNCD occurred in 38 of the 90 elderly patients, with an incidence of 42.2%. The level of Aβ42 in the cerebrospinal fluid was significantly lower in PNCD group than in the nonPNCD group (1.96 vs 2.54 ng/mL; t=3.29, P < 0.05); the concentration of NFL in the cerebrospinal fluid was significantly higher in PNCD group than in non- PNCD group (4.59 vs 3.16 ng/mL; t=3.72, P < 0.05). Aβ42 level in the cerebrospinal fluid was positively correlated while NFL was negatively correlated with the MMSE score of the patients (r=-0.659, P < 0.05; r=-0.626, P < 0.05). ROC curve analysis showed that the area under the curve (AUC) of cerebrospinal fluid Aβ42 and NFL levels were 0.744 and 0.768, respectively; the AUC of their combination was 0.847 for prediction of PNCD.

OBJECTIVE

Elderly patients with PNCD have significantly higher levels of Aβ42 and NFL in the cerebrospinal fluid than those without PNCD. Both Aβ42 and NFL levels in the cerebrospinal fluid can help to predict the occurrence of POCD in elderly patients, and their combination has a higher diagnostic value.

Association of Olfactory Impairment and Postoperative Cognitive Dysfunction in Elderly Patients

OBJECTIVE

To investigate the impact of anesthesia on the change of olfactory function and cognitive function in elderly patients who undergo abdominal surgery.

METHODS

A total of 30 elderly patients who underwent abdominal surgery were recruited as the research subjects. The Connecticut Chemosensory Clinical Research Center (CCCRC) olfactory test was used to test the olfactory function and the Mini-mental State Examination (MMSE), Hopkins Verbal Learning Test - Revised (HVLT-R), Trail Making Test (TMT), Stroop Color Word Test (SCWT), Digit-Symbol Coding Test (DSCT), and Verbal Fluency Test (VFT) were used to assess their cognitive function before general anesthesia, and on the 3rd and 7th day post-anesthesia. The serum level of IL-1β, IL-6, and TNF-α were measured before anesthesia and at 0, 12, and 24 h post-anesthesia. In total, 30 healthy volunteers who did not undergo anesthesia were used as the control group. The test results of all subjects were recorded and their correlations were analyzed.

RESULTS

On the 3rd and 7th day post-anesthesia, the olfactory recognition threshold of patients in the surgical group was lower than that of control group with significant difference (P < 0.05). On the 3rd and 7th postoperative day, the patient's short-term memory and delayed memory, attention and processing speed were decreased (P < 0.05). On the 7th day post-anesthesia, delayed memory and processing ability were still decreased (P < 0.05). In the surgical group, Spearman correlation analysis showed that the difference of olfactory recognition score on the 3rd and 7th day post-anesthesia was positively correlated with short-term memory and delayed memory of cognitive function. Compared with pre-anesthesia, the serum levels of IL-1β, IL-6, and TNF-α in the surgical group were significantly increased at each time point after anesthesia.

CONCLUSION

Abdominal surgery with general anesthesia in elderly patients may increase the level of serum inflammatory factors, induce olfactory impairment, particularly the decline of olfactory identification threshold and cause cognitive dysfunction with declined short-term memory, delayed memory and attention. There was a positive correlation between olfactory impairment and cognitive dysfunction after general anesthesia. Therefore, olfactory impairment could be an early indicator to guide early intervention for postoperative cognitive dysfunction.

Insulin-like growth factor-1 improves postoperative cognitive dysfunction following splenectomy in aged rats

Postoperative cognitive dysfunction (POCD) is a serious complication following anesthesia and operations in aged patients undergoing surgical intervention. It is characterized by temporary or permanent cognitive decline, memory impairment and deterioration in language comprehension and social adaption ability. Therefore, the development of POCD prevention and treatment tools has become an area of interest. The current study assessed the therapeutic effects of insulin-like growth factor-1 (IGF-1) on POCD in aged rats and explored the underlying mechanisms. Model rats underwent splenectomy under 1.5-2% isoflurane and mechanical ventilation. IGF-1 (50 µg/kg) was diluted in normal saline and administered by abdominal hypodermic injection daily from the operation to day 7 post-operation. Following splenectomy, the animals showed marked cognitive impairment as determined by the Morris water maze test. Hippocampal protein levels of amyloid precursor protein (APP), β-site APP-cleaving enzyme-1 (BACE-1), amyloid-β (Aβ), capase3, Bax and Bcl-2 were assessed by immunoblotting. Neuronal apoptosis in the hippocampus was analyzed using a TUNEL assay. The results demonstrated that the levels of APP, BACE-1, Aβ, caspase3 and Bax were increased following splenectomy, while the levels of Bcl2 were reduced at days 1, 3 and 7 post-operation in aged rats. However, IGF-1 downregulated APP, BACE-1, Aβ, capase3 and Bax, and upregulated Bcl2 at these time points following splenectomy. TUNEL staining revealed that administration of IGF-1 significantly reduced neuronal apoptosis in the hippocampal CA1 region following splenectomy. These results indicated that IGF-1 decreased Aβ-protein production and inhibited neuronal apoptosis in the hippocampus following splenectomy, subsequently alleviating POCD.

Cognitive Dysfunction and Mortality After Carotid Endarterectomy

Background: Carotid endarterectomy (CEA) has been associated with both postoperative cognitive dysfunction (POCD) and improvement (POCI). However, the prognostic significance of postoperative cognitive changes related to CEA is largely unknown. The aim of this study was to examine the associations between postoperative cognitive changes after CEA and long-term survival.

Methods: We studied 43 patients 1 day before CEA as well as 4 days and 3 months after surgery with an extensive neuropsychological test array, and followed them for up to 14 years. POCD and POCI relative to baseline were determined with the reliable change index derived from 17 healthy controls. Associations between POCD/POCI and mortality within the patient group were studied with Cox regression analyses adjusted for confounders.

Results: POCD in any functional domain was evident in 28% of patients 4 days after surgery and in 33% of patients 3 months after surgery. POCI was shown in 23% of patients at 4 days and in 44% of patients at 3 months. POCD at 3 months was associated with higher long-term mortality (hazard ratio 5.0, 95% CI 1.8–13.9, p = 0.002) compared with patients with no cognitive decline.

Conclusions: Our findings suggest that POCD in a stable phase, 3 months after CEA predicts premature death. Evaluation of postoperative cognitive changes is essential, and POCD in a stable phase after CEA should prompt scrutiny of underlying factors and better adherence to therapies to prevent recurrences and to promote early intervention in imminent deterioration.

Dexmedetomidine improves early postoperative neurocognitive disorder in elderly male patients undergoing thoracoscopic lobectomy

Perioperative neurocognitive disorder (PND) is a common complication following thoracic surgery that frequently occurs in patients ≥65 years. PND includes postoperative cognitive dysfunction (POCD) and postoperative delirium (POD). To investigate whether intravenous dexmedetomidine (DEX) is able to improve neurocognitive function in elderly male patients following thoracoscopic lobectomy, a randomized, double-blinded, placebo-controlled trial was performed at the Affiliated Hospital of Inner Mongolia Medical University (Hohhot, China). Patients aged ≥65 years were enrolled and were subjected to thoracic surgery under general anesthesia. A computer-generated randomization sequence was used to randomly assign patients (at a 1:1 ratio) to receive either intravenous DEX (0.5 µg/kg per h, from induction until chest closure) or placebo (intravenous normal saline). The primary endpoint was the result of the Mini-Mental State Examination (MMSE). The secondary endpoints were the results of the Montreal Cognitive Assessment (MoCA) and those obtained with the Confusion Assessment Method (CAM), as well as the incidence of POCD and POD during the first 7 postoperative days. Other observational indexes included sleep quality at night, self-anxiety scale prior to the operation and 7 days following the operation and the visual analogue scale (VAS) score at rest and during movement on the first and third day following the operation. Furthermore, at 6 h following surgery, the MMSE score in the DEX group was significantly higher than that in the saline group. At 6 h and on the first day postoperatively, the MoCA score in the DEX group was significantly higher than that in the saline group. The incidence of POCD and POD in the DEX group was 13.2 and 7.5%, respectively, while that in the saline group was 35.8 and 11.3%, respectively. There was a significant difference in the incidence of POCD between the two groups (P<0.01). In the DEX group, mean sleep quality was increased, whereas the mean VAS was decreased compared with the corresponding values in the saline group. In conclusion, elderly male patients who underwent thoracoscopic lobectomy under continuous infusion of DEX (0.5 µg/kg/h) exhibited a reduced incidence of POCD during the first 7 postoperative days as compared with the placebo group. Furthermore, DEX improved the subjective sleep quality in the first postoperative night, reduced anxiety and alleviated postoperative pain. In addition, it increased the incidence of bradycardia. The present study was registered in the Chinese Clinical Trial Registry (www.chictr.org.cn; registration no. ChiCTR-IPR-17010958).

Overexpression of lncRNA Gm43050 alleviates apoptosis and inflammation response induced by sevoflurane treatment by regulating miR-640/ZFP91

AIMS

The present study investigated the function and mechanism of lncRNA Gm43050 in sevoflurane-induced abnormal cognition.

METHODS

Primary hippocampal neurons were used to establish the model of abnormal cognitive disorder. Overexpression and knockdown experiments were performed to analyze cell death rates, proliferation, apoptosis and the inflammatory response. The dual-luciferase reporter assay was used to analyze the potential binding targets of lncRNA Gm43050. Rescue experiments were used to assess the downstream targets of Gm43050.

RESULTS

We found that lncRNA Gm43050 was in the cytoplasm. Overexpression of lncRNA Gm43050 had no impact on proliferation but significantly reduced the cell death rates and apoptosis. The inflammation markers IL-6, IL-1β, IL-8 and TNF-α were manifestly downregulated in the overexpression group. Opposite effects were detected in the lncRNA Gm43050 knockdown group. Bioinformatics analysis showed that miR-640 may be the potential target of Gm43050. Additionally, we found that ZFP91 was the downstream target of miR-640.

CONCLUSION

We provided comprehensive data of the function and mechanism of lncRNA Gm43050 in abnormal cognition. Our study showed that lncRNA Gm43050 exerted its important role via the regulation of miR-640 and ZFP91.

The MARBLE Study Protocol: Modulating ApoE Signaling to Reduce Brain Inflammation, DeLirium, and PostopErative Cognitive Dysfunction

BACKGROUND

Perioperative neurocognitive disorders (PND) are common complications in older adults associated with increased 1-year mortality and long-term cognitive decline. One risk factor for worsened long-term postoperative cognitive trajectory is the Alzheimer's disease (AD) genetic risk factor APOE4. APOE4 is thought to elevate AD risk partly by increasing neuroinflammation, which is also a theorized mechanism for PND. Yet, it is unclear whether modulating apoE4 protein signaling in older surgical patients would reduce PND risk or severity.

OBJECTIVE

MARBLE is a randomized, blinded, placebo-controlled phase II sequential dose escalation trial designed to evaluate perioperative administration of an apoE mimetic peptide drug, CN-105, in older adults (age≥60 years). The primary aim is evaluating the safety of CN-105 administration, as measured by adverse event rates in CN-105 versus placebo-treated patients. Secondary aims include assessing perioperative CN-105 administration feasibility and its efficacy for reducing postoperative neuroinflammation and PND severity.

METHODS

201 patients undergoing non-cardiac, non-neurological surgery will be randomized to control or CN-105 treatment groups and receive placebo or drug before and every six hours after surgery, for up to three days after surgery. Chart reviews, pre- and postoperative cognitive testing, delirium screening, and blood and CSF analyses will be performed to examine effects of CN-105 on perioperative adverse event rates, cognition, and neuroinflammation. Trial results will be disseminated by presentations at conferences and peer-reviewed publications.

CONCLUSION

MARBLE is a transdisciplinary study designed to measure CN-105 safety and efficacy for preventing PND in older adults and to provide insight into the pathogenesis of these geriatric syndromes.

Microarray Expression Profiles of lncRNAs and mRNAs in Postoperative Cognitive Dysfunction

Postoperative cognitive dysfunction (POCD) is serious disorder in the central nervous system common in aged patients after anesthesia. Although its clinical symptoms are well recognized, however, the molecular etiology of the POCD remains unrevealed. Similarly, neither gold standard molecular diagnosis nor effective treatment is available for POCD until the present. Therefore, we aimed to explore the molecular mechanism of this disorder through investigating lncRNAs and mRNAs associated with POCD human patients and investigate their underlying regulatory pathways. In this study, we recruited 200 patients requiring hip or knee replacement surgery. Their neurological functions were assessed at two time points, 1 day before the surgery and 30 days post-surgery. In parallel, serum samples were collected from the participants to analyze lncRNAs and mRNAs differential expression profile between POCD and non-POCD patients using microarray analysis. To further investigate the role differentially expressed mRNA and lncRNAs, Gene Ontology (GO), pathway analyses on mRNAs and lncRNA-mRNA interaction network were performed. As a result, 68 lncRNAs and 115 mRNAs were dysregulated in the POCD group compared to non-POCD group. Among them, the top 10 upregulated lncRNAs and 10 downregulated lncRNAs were listed for enrichment analysis. Interestingly, we found that these lncRNA and mRNA are involved in biological process, molecular function, and cellular component in addition to various signaling pathways, suggesting that the pathogenesis of POCD involves lncRNAs and mRNAs differential expression. Consequently, the genetic dysregulation between the non-POCD and POCD patients participates in the occurrence and development of POCD, and could be served as diagnostic biomarkers and drug targets for POCD treatment.