Inhaled sevoflurane may promote progression of amnestic mild cognitive impairment: a prospective, randomized parallel-group study

Comparison of Propofol-Based Total Intravenous Anesthesia versus Volatile Anesthesia with Sevoflurane for Postoperative Delirium in Adult Coronary Artery Bypass Grafting Surgery: A Prospective Randomized Single-Blinded Study

OBJECTIVES

To compare the incidence of delirium and early (at 1 week) postoperative cognitive dysfunction (POCD) between propofol-based total intravenous anesthesia (TIVA) and volatile anesthesia with sevoflurane in adult patients undergoing elective coronary artery bypass graft surgery (CABG) with cardiopulmonary bypass (CPB).

DESIGN

This was a prospective randomized single-blinded study.

SETTING

The study was conducted at a single institution, the Sree Chitra Tirunal Institute for Medical Sciences and Technology, a tertiary care institution and university-level teaching hospital.

PARTICIPANTS

Seventy-two patients undergoing elective CABG under CPB participated in this study.

INTERVENTIONS

This study was conducted on 72 adult patients (>18 years) undergoing elective CABG under CPB who were randomized to receive propofol or sevoflurane. Anesthetic depth was monitored to maintain the bispectral index between 40 and 60. Delirium was assessed using the Confusion Assessment Method for the Intensive Care Unit. Early POCD was diagnosed when there was a reduction of >2 points in the Montreal Cognitive Assessment score compared to baseline. Cerebral oximetry changes using near-infrared spectroscopy (NIRS), atheroma grades, and intraoperative variables were compared between the 2 groups.

MEASUREMENTS & MAIN RESULTS

Seventy-two patients were randomized to receive propofol (n = 36) or sevoflurane (n = 36). The mean patient age was 59.4 ± 8.6 years. The baseline and intraoperative variables, including atheroma grades, NIRS values, hemoglobin, glycemic control, and oxygenation, were comparable in the 2 groups. Fifteen patients (21.7%) patients developed delirium, and 31 patients (44.9%) had early POCD. The incidence of delirium was higher with sevoflurane (n = 12; 34.2%) compared to propofol (n = 3; 8.8%) (odds ratio [OR], 1.72; 95% confidence interval [CI], 1.13-2.62; p = 0.027)*. POCD was higher with sevoflurane (n = 20; 57.1%) compared to propofol (n = 11; 32.3%) (OR, 1.63; 95% CI, 1.01-2.62; p = 0.038)*. In patients aged >65 years, delirium was higher with sevoflurane (7/11; 63.6%) compared to propofol (1/7; 14.2%) (p = 0.03)*.

CONCLUSIONS

Propofol-based TIVA was associated with a lower incidence of delirium and POCD compared to sevoflurane in this cohort of patients undergoing CABG under CPB. Large-scale, multicenter randomized trials with longer follow-up are needed to substantiate the clinical relevance of this observation.

General anesthesia is not associated with dementia in older adults with osteoarthritis for hip/knee replacements, a national population-based nested case-control study

BACKGROUND

Dementia is a prevalent neurological condition, yet the relationship between dementia and general anesthesia remains uncertain. The study aimed to explore the association between general anesthesia and dementia using a nationwide population-based database.

METHODS

The study extracted data from Taiwan's national health insurance, which encompassed the records of one million insured residents. A total of 59,817 patients aged 65 years and above, diagnosed with osteoarthritis between 2002 and 2010, were included. Among these patients, 3277 individuals with an initial diagnosis of dementia between 2004 and 2013 were matched with non-dementia patients based on age, gender, and the date of osteoarthritis diagnosis. Following a 1:2 random matching, the case group included 2171 patients with dementia, while the control group consisted of 4342 patients without dementia. The data was analyzed using conditional and unconditional logistic regressions.

RESULTS

No significant differences in the odds of dementia were found between individuals exposed to general and regional anesthesia during hip/knee replacement surgeries (OR = 1.11; 95%CI: 0.73-1.70), after adjusting for age, sex, and co-morbidities. Similarly, there were no significant differences in the odds of dementia based on different durations of anesthesia exposure (General: <2 h: OR = 0.91, 95%CI = 0.43-1.92; 2-4 h: OR = 1.21, 95%CI = 0.82-1.79; >4 h: OR = 0.39, 95%CI = 0.15-1.01; compared to no exposure. Regional: <2 h: OR = 1.18, 95%CI = 0.85-1.62; 2-4 h: OR = 0.9, 95%CI = 0.64-1.27; >4 h: OR = 0.55, 95%CI = 0.15-1.96; compared to no exposure). Likewise, no significant differences were observed in the odds of dementia based on the number of replacement surgeries (twice: OR = 0.74, 95%CI = 0.44-1.23, compared to once).

CONCLUSION

Neither general anesthesia nor regional anesthesia in hip/knee surgery was associated with dementia. Different numbers and durations of anesthesia exposure showed no significant differences in the odds for dementia.

Mortality and morbidity after total intravenous anaesthesia versus inhalational anaesthesia: a systematic review and meta-analysis

Background

General anaesthesia is provided to more than 300 million surgical patients worldwide, every year. It is administered either through total intravenous anaesthesia, using only intravenous agents, or through inhalational anaesthesia, using volatile anaesthetic agents. The debate on how this affects postoperative patient outcome is ongoing, despite an abundance of published trials. The relevance of this topic has grown by the increasing concern about the contribution of anaesthetic gases to the environmental impact of surgery. We aimed to summarise all available evidence on relevant patient outcomes with total intravenous anaesthesia versus inhalational anaesthesia.

Methods

In this systematic review and meta-analysis, we searched PubMed/Medline, Embase and Cochrane Central Register of Controlled trials for works published from January 1, 1985 to August 1, 2023 for randomised controlled trials comparing total intravenous anaesthesia using propofol versus inhalational anaesthesia using the volatile anaesthetics sevoflurane, desflurane or isoflurane. Two reviewers independently screened titles, abstracts and full text articles, and assessed risk of bias using the Cochrane Collaboration tool. Outcomes were derived from a recent series of publications on consensus definitions for Standardised Endpoints for Perioperative trials (StEP). Primary outcomes covered mortality and organ-related morbidity. Secondary outcomes were related to anaesthetic and surgical morbidity. This study is registered with PROSPERO (CRD42023430492).

Findings

We included 317 randomised controlled trials, comprising 51,107 patients. No difference between total intravenous and inhalational anaesthesia was seen in the primary outcomes of in-hospital mortality (RR 1.05, 95% CI 0.67-1.66, 27 trials, 3846 patients), 30-day mortality (RR 0.97, 95% CI 0.70-1.36, 23 trials, 9667 patients) and one-year mortality (RR 1.14, 95% CI 0.88-1.48, 13 trials, 9317 patients). Organ-related morbidity was similar between groups except for the subgroup of elderly patients, in which total intravenous anaesthesia was associated with a lower incidence of postoperative cognitive dysfunction (RR 0.62, 95% CI 0.40-0.97, 11 trials, 3834 patients) and a better score on postoperative cognitive dysfunction tests (standardised mean difference 1.68, 95% CI 0.47-2.88, 9 trials, 4917 patients). In the secondary outcomes, total intravenous anaesthesia resulted in a lower incidence of postoperative nausea and vomiting (RR 0.61, 95% CI 0.56-0.67, 145 trials, 23,172 patients), less emergence delirium (RR 0.40, 95% CI 0.29-0.56, 32 trials, 4203 patients) and a higher quality of recovery score (QoR-40 mean difference 6.45, 95% CI 3.64-9.25, 17 trials, 1835 patients).

Interpretation

The results indicate that postoperative mortality and organ-related morbidity was similar for intravenous and inhalational anaesthesia. Total intravenous anaesthesia offered advantages in postoperative recovery.

Funding

Dutch Society for Anaesthesiology (NVA).

Anesthesia and dementia: An up-to-date review of the existing literature

Concerns around the impact of anesthesia on cognitive decline and dementia, including Alzheimer's Disease (AD), have been increasing and recently attracting considerable attention in the research community. One unanswered question is whether anesthesia is a risk factor of dementia, specifically AD type dementia. A large body of evidence, coming from in vivo and in vitro models, suggests that exposure to anesthetic agents may increase the risk of AD through mechanisms of action similar to AD's neuropathology. In terms of clinical studies, our knowledge of the relationship between anesthesia and dementia is based on limited data, with most studies suggesting that there is no association. The aim of this paper was therefore to outline recent clinical studies exploring this controversial relationship and discuss future directions in terms of study design and potential areas of study. As the aging population and the prevalence of dementia and AD increases, we need a better understanding of anesthesia as a risk factor for neurodegeneration through well-designed studies. Despite the controversy, there seems to be little evidence to support that anesthesia itself or other surgical and patient factors can cause or accelerate AD.

The Association Between Surgery and Mild Cognitive Impairment: Insight from a Case-Control Study

Background

Surgery may be associated with postoperative cognitive impairment in elder participants, yet the extent of its association with mild cognitive impairment (MCI) remains undetermined.

Objective

To determine the relationship between surgery and MCI.

Methods

The data of participants from the Alzheimer's Disease Neuroimaging Initiative were analyzed, including individuals with MCI or normal cognition. We focused on surgeries conducted after the age of 45, categorized by the number of surgeries, surgical risk, and the age at which surgeries occurred. Multivariable logistic regression was employed to determine the association between surgery and the development of MCI.

Results

The study is comprised of 387 individuals with MCI and 578 cognitively normal individuals. The overall surgery exposure (adjusted OR = 1.14, [95% CI 0.83, 1.56], p = 0.43) and the number of surgeries (adjusted OR = 0.92  [0.62, 1.36], p = 0.67 for single exposure, adjusted OR = 1.12 [0.71, 1.78], p = 0.63 for two exposures, adjusted OR = 1.38 [0.95, 2.01], p = 0.09 for three or more exposures compared to no exposure as the reference) were not associated with the development of MCI. However, high-risk surgeries (adjusted OR = 1.79 [1.00, 3.21], p = 0.049) or surgeries occurring after the age of 75 (adjusted OR = 2.01 [1.03, 3.90], p = 0.041) were associated with a greater risk of developing MCI.

Conclusions

High risk surgeries occurring at an older age contribute to the development of MCI, indicating a complex of mechanistic insights for the development of postoperative cognitive impairment.

MiR-34a targets SIRT1 to reduce p53 deacetylation and promote sevoflurane inhalation anesthesia-induced neuronal autophagy and apoptosis in neonatal mice

This study is to investigate the function of miR-34a and interactions between miR-34a, SIRT1, and p53 in sevoflurane-induced neuronal apoptosis and autophagy in neonatal mice. A mouse model was established by inhalation anesthesia with sevoflurane and injected with genetic reagents, followed by tests of learning and memory abilities and histological staining of the hippocampus. CCK-8 and AnnexinV/PI staining respectively measured the survival and apoptosis rates of primary hippocampal neurons cultured with sevoflurane. The expression levels of miR-34a, SIRT1, p53, Ac-p53, and autophagy- or apoptosis-related proteins were measured. Sevoflurane impaired the learning and memory abilities of mice, increased TUNEL-positive cells in their hippocampus, and hindered the survival of hippocampal neurons. Sevoflurane increased miR-34a, Bax, cleaved caspase-3, and the ratio of LC3-II/LC3-I and reduced SIRT1 and p62. MiR-34a overexpression promoted sevoflurane-induced neural damage, whereas SIRT1 inhibition or p53 upregulation counteracted the neuroprotection of miR-34a knockdown. SIRT1 was a target of miR-34a and promoted p53 deacetylation. MiR-34a promotes sevoflurane-stimulated neuronal apoptosis and autophagy in neonatal mice by inhibiting SIRT1 expression and subsequent p53 deacetylation.

Luteoloside Prevents Sevoflurane-induced Cognitive Dysfunction in Aged Rats via Maintaining Mitochondrial Function and Dynamics in Hippocampal Neurons

Postoperative cognitive dysfunction (POCD) is characterized by impaired cognitive function, such as decreased learning and memory after anesthesia and surgery. This study aimed to explore the effect of luteoloside, a flavonoid extracted from natural herbs, on sevoflurane-induced cognitive dysfunction. Aged Sprague-Dawley male rats (20 months old) were treated with luteoloside for 7 days prior to sevoflurane exposure. After evaluation using an open field, novel object recognition, and Y-maze tests, it was determined that luteoloside effectively prevented sevoflurane-induced cognitive dysfunction. Sevoflurane exposure led to hippocampal neuron apoptosis in vivo (n = 6) and in vitro (n = 3), while this injury was prevented by luteoloside in a dose-dependent manner. Mechanistically, luteoloside maintained mitochondrial function and dynamics, as evidenced by the restored adenosine triphosphate (ATP) production and mitochondrial membrane potential as well as the upregulated levels of mitochondrial fission (optic atrophy protein 1 (Opa1) and mitofusin1 (Mfn1)) and downregulated mitochondrial fusion (mitochondrial fission 1 (Fisl) and dynamin-related protein 1 (Drp1)) factors. Notably, silencing Opa1 blocked the protective effect of luteoloside on hippocampal neurons and mitochondrial function. In summary, luteoloside prevented sevoflurane-induced cognitive dysfunction in aged rats, which may be achieved by regulating mitochondrial dynamics. Our study reveals the potential of luteoloside in preventing POCD in aged patients.

Dementia risk after major elective surgery based on the route of anaesthesia: A propensity score-matched population-based cohort study

Background

Whether the route of anaesthesia is an independent risk factor for dementia remains unclear. Therefore, we conducted a propensity score-matched (PSM) population-based cohort study to compare dementia incidence among surgical patients undergoing different routes of anaesthesia.

Methods

The inclusion criteria were being an inpatient >20 years of age who underwent major elective surgery, defined as those requiring GA without or with inhalation anaesthetics or regional anaesthesia, and being hospitalised for >1 day between Jan 1, 2008 and Dec 31, 2019 in Taiwan. Patients undergoing major elective surgery were categorised into three groups according to the type of anaesthesia administered: noninhalation anaesthesia, inhalation anaesthesia, and regional anaesthesia, matched at a 1:1 ratio. The incidence rate (IR) of dementia was determined.

Findings

PSM yielded 63,750 patients (21,250 in the noninhalation anaesthesia group, 21,250 in the inhalation anaesthesia group, and 21,250 in the regional anaesthesia group). In the multivariate Cox regression analysis, the adjusted hazard ratios (aHRs; 95% confidence intervals) of dementia for the inhalation and noninhalation anaesthesia groups compared with the regional anaesthesia group were 20.16 (15.40-26.35; p < 0.001) and 18.33 (14.03-24.04; p < 0.001), respectively. The aHR of dementia for inhalation anaesthesia compared with noninhalation anaesthesia was 1.13 (1.03-1.22; p = 0.028). The IRs of dementia for the inhalation, noninhalation, and regional anaesthesia groups were 3647.90, 3492.00, and 272.99 per 100,000 person-years, respectively.

Interpretation

In this population based cohort study, the incidence of dementia among surgical patients undergoing general anaesthesia was higher than among those undergoing regional anaesthesia. Among patients undergoing general anaesthesia, inhalation anaesthesia was associated with a higher risk of dementia than noninhalation anaesthesia. Our results should be confirmed in a randomised controlled trial.

Funding

The study was partially supported by Lo-Hsu Medical Foundation, Lotung Poh-Ai Hospital (Funding Number: 10908, 10909, 11001, 11002, 11003, 11006, and 11013).

A novel predictive strategy for the incidence of postoperative neurocognitive dysfunction in elderly patients with mild cognitive impairment

Objective: Preoperative levels of cognition-related biomarkers and intraoperative cerebral ischemia and hypoxia might cause postoperative neurocognitive dysfunction (PND). The aim of this study was to evaluate the predictive ability of preoperative plasma biomarkers along with cerebral oxygen saturation (SctO₂) for the incidence of PND in elderly patients with mild cognitive impairment (MCI).

Methods: A total of 210 patients aged 65–80 years undergoing spinal surgery were randomly assigned to three groups (n = 70 each): propofol, sevoflurane, and propofol/sevoflurane as anesthesia maintenance protocols. Propofol was administrated target-controlled infusion of 4 μg/ml (group P), the minimum alveolar concentration (MAC) of inhalation anesthetic sevoflurane was 1.3 (group S), and propofol was injected with a target-controlled plasma concentration of 1.2 μg/ml, accompanied by sevoflurane inhalation 0.7 MAC (group PS). Cognitive function was evaluated 1 day preoperatively and on the 7th day postoperatively. Preoperative levels of amyloidβ-40 (Aβ-40), Aβ-42, total tau protein (T-tau), phosphorylated tau protein (P-tau), and triggering receptors on myeloid cells-2 (TREM2) were investigated. SctO₂ was monitored intraoperatively.

Results: Aβ-42 had the strongest significant correlation with preoperative MoCA score. The value of Aβ-42 associated with a high risk of PND was 28.34 pg/ml, and the area under the curve (AUC) was predicted to be 0.711. When the preoperative level of Aβ-42 was 28.34 pg/ml, SctO_2max% was 9.92%. The AUC was predicted to be 0.872, and the sensitivity and specificity were 0.833 and 0.841, respectively.

Conclusion: Under the conditions of preoperative Aβ-42 less than 28.34 pg/ml, the intraoperative fluctuation range of cerebral oxygen saturation should be maintained within 9.92% to reduce the occurrence of PND in geriatric patients with MCI.

Postoperative Cognitive Dysfunction and Alzheimer’s Disease: A Transcriptome-Based Comparison of Animal Models

Background

Postoperative cognitive dysfunction (POCD) is a common complication characterized by a significant cognitive decline. Increasing evidence suggests an association between the pathogenesis of POCD and Alzheimer’s disease (AD). However, a comprehensive understanding of their relationships is still lacking.

Methods

First, related databases were obtained from GEO, ArrayExpress, CNGB, and DDBJ repositories. De novo analysis was performed on the raw data using a uniform bioinformatics workflow. Then, macro- and micro-level comparisons were conducted between the transcriptomic changes associated with AD and POCD. Lastly, POCD was induced in male C57BL/6j mice and the hippocampal expression levels of mRNAs of interest were verified by PCR and compared to those in AD congenic models.

Results

There was a very weak correlation in the fold-changes in protein-coding transcripts between AD and POCD. Overall pathway-level comparison suggested that AD and POCD are two disease entities. Consistently, in the classical AD pathway, the mitochondrial complex and tubulin mRNAs were downregulated in both the POCD hippocampus and cortex. POCD and AD hippocampi might share the same pathways, such as tryptophan metabolism, but undergo different pathological changes in phagosome and transferrin endocytosis pathways. The core cluster in the hippocampal network was mainly enriched in mitosis-related pathways. The hippocampal expression levels of genes of interest detected by PCR showed good consistency with those generated by high throughput platforms.

Conclusion

POCD and AD are associated with different transcriptomic changes despite their similar clinical manifestations. This study provides a valuable resource for identifying biomarkers and therapeutic targets for POCD.

Inhibition of Adult Hippocampal Neurogenesis Plays a Role in Sevoflurane-Induced Cognitive Impairment in Aged Mice Through Brain-Derived Neurotrophic Factor/Tyrosine Receptor Kinase B and Neurotrophin-3/Tropomyosin Receptor Kinase C Pathways

Sevoflurane anesthesia induces cognitive impairment, which may lead to perioperative neurocognitive disorders (PND). However, the factors and molecular mechanism underlying this impairment remains unclear. Adult hippocampal neurogenesis (AHN) in the subgranular zone of the hippocampus has been implicated in cognitive processes. Nonetheless, the direct role of AHN in sevoflurane-induced cognitive impairment has never been demonstrated. In this study, we explored the age and the concentration factors and the role of AHN inhibition in sevoflurane-induced cognitive impairment in sevoflurane inhalation model mice. We found that 3% sevoflurane exposure induced significant cognitive impairment and inhibition of AHN in aged mice but not adult mice. Expression of BDNF/TrkB and NT-3/TrkC was also decreased by 3% sevoflurane exposure in aged mice. Hippocampal brain-derived neurotrophic factor (BDNF) or Neurotrophin-3 (NT-3) microinjection could partially improve the sevoflurane-induced cognitive impairment and AHN inhibition, respectively. These results demonstrate that the cognitive impairment caused by sevoflurane inhalation is related to patient age and sevoflurane concentration. In conclusion, the molecular mechanism of cognitive impairment in the elderly is related to the inhibition of AHN through the BDNF/TrkB and NT-3/TrkC pathways. Thus, sevoflurane inhalation anesthesia may be safe for adult patients, but caution should be exercised when administering it to the elderly.

Hypercholesterolemia aggravates sevoflurane-induced cognitive impairment in aged rats by inducing neurological inflammation and apoptosis

We aimed to explore the effects of hypercholesterolemia on sevoflurane-induced cognitive impairment in aged rats and the underlying mechanism(s). Aged rats were administrated with high-fat diet, sevoflurane, or both. Thereafter, the plasma levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) were evaluated. The Morris water maze task was performed to evaluate the spatial learning and memory ability of rats. Moreover, Nissl and Evans blue staining were conducted to test nerve damage and detect the blood-brain barrier permeability, respectively. The percentage of apoptotic cells was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling assay. The messenger RNA expression of inflammatory factors and protein expression of microglial activation markers and apoptosis-related proteins were tested by real-time polymerase chain reaction, enzyme-linked immunosorbent assay, or western blot analysis, respectively. High-fat diet induced high levels of TC, TG, and LDL but decreased levels of HDL. However, sevoflurane had no effects on these levels. In contrast, sevoflurane significantly induced the impairment of learning and memory, nerve damage, neuroinflammatory damage, and neuronal apoptosis. Hypercholesterolemia exacerbated the sevoflurane-induced impairment in aged rats. These results suggested that hypercholesterolemia aggravates sevoflurane-induced cognitive impairment in aged rats, possibly by inducing neurological inflammation and apoptosis.

Sulforaphane ameliorates amyloid-β-induced inflammatory injury by suppressing the PARP1/SIRT1 pathway in retinal pigment epithelial cells

Age-associated macular degeneration (AMD) is a progressive eye disorder that leads to irreversible impairment of central vision, and effective therapies are lacking. Here, we explore how oligomeric amyloid-β_1-42 can trigger inflammatory injury in retinal pigment epithelial cells and how sulforaphane can mitigate such injury. ARPE-19 retinal pigment epithelial cells expressing low, endogenous, or high levels of poly(ADP-ribose) polymerase (PARP1) were treated with oligomeric amyloid-β_1-42 in the presence or absence of various signaling inhibitors or sulforaphane. Cell viability, apoptosis, inflammatory responses, and activity of the PARP1/Sirtuin (SIRT1) axis were assayed. Treating ARPE-19 cells with oligomeric amyloid-β_1-42 promoted the production of IL-1β, IL-6, IL-8, and TNF-ɑ, which was partially reversed by inhibiting PARP1 and activating SIRT1. PARP1 was found to act upstream of SIRT1, and expression of the two proteins correlated negatively with each other. Sulforaphane also mitigated the injury due to oligomeric amyloid-β_1-42 through a mechanism involving inactivation of the PARP1/SIRT1 pathway. Oligomeric amyloid-β_1-42 can trigger AMD-like injury in retinal pigment epithelium by activating PARP1 and repressing SIRT1. Moreover, sulforaphane can induce cell viability and SIRT1 expression, but reduce cell apoptosis, the activity of caspase-3 or -9, and PARP1 expression in oAβ_1-42-treated cells. However, PARP1 inactivation or SIRT1 activation weaken these effects. In summary, sulforaphane reduces the inflammatory injury induced by oAβ_1-42 in ARPE-19 cell by inactivating the PARP1/SIRT1 pathway. Thus, the compound may be an effective therapy against AMD.

Longitudinal Study of the Association between General Anesthesia and Increased Risk of Developing Dementia

The association between exposure to general anesthesia (GA) and the risk of dementia is still undetermined. To investigate a possible link to the development of dementia in older people who have undergone GA, we analyzed nationwide representative cohort sample data from the Korean National Health Insurance Service. The study cohort comprised patients over 55 years of age who had undergone GA between January 2003 and December 2004 and consisted of 3100 patients who had undergone GA and 12,400 comparison subjects who had not received anesthesia. After the nine-year follow-up period, we found the overall incidence of dementia was higher in the patients who had undergone GA than in the comparison group (10.5 vs. 8.8 per 1000 person-years), with the risk being greater for women (adjusted HR of 1.44; 95% CI, 1.19–1.75) and those with comorbidities (adjusted HR of 1.39; 95% CI, 1.18–1.64). Patients who underwent GA showed higher risks for Alzheimer’s disease and vascular dementia (adjusted HR of 1.52; 95% CI, 1.27–1.82 and 1.64; 95% CI, 1.15–2.33, respectively). This longitudinal study using a sample cohort based on a nationwide population sample demonstrated a significant positive association between GA and dementia, including Alzheimer’s disease and vascular dementia.

Sevoflurane-Induced miR-211-5p Promotes Neuronal Apoptosis by Inhibiting Efemp2

Sevoflurane exposure can result in serious neurological side effects including neuronal apoptosis and cognitive impairment. Although the microRNA miR-211-5p is profoundly upregulated following sevoflurane exposure in neonatal rodent models, the impact of miR-211-5p on neuronal apoptosis and cognitive impairment postsevoflurane exposure has not yet been elucidated. Here, we found that sevoflurane upregulated miR-211-5p and downregulated EGF-Containing Fibulin Extracellular Matrix Protein 2 (Efemp2, Fibulin-4) levels in vitro and in vivo. Sevoflurane's effect on miR-211-5p expression was based on enhancing primary miR-211 transcription. miR-211-5p targets Efemp2's mRNA 3′-untranslated region, reducing Efemp2 expression. RNA immunoprecipitation revealed significant enrichment of the miR-211-5p:Efemp2 mRNA dyad in the RNA-induced silencing complex. miR-211-5p mimics downregulated Efemp2, leading to phosphorylation of Smad2 and Smad3, upregulation of pro-apoptotic Bim, and mitochondrial release of allograft inflammatory factor 1 and cytochrome C. In contrast, miR-211-5p hairpin inhibitor (AntimiR-211-5p) negatively regulated this apoptotic pathway and reduced neuronal apoptosis in an Efemp2-dependent manner. Sevoflurane-exposed mice administered AntimiR-211-5p displayed reduced cortical apoptosis levels and near-term cognitive impairment. In conclusion, sevoflurane-induced miR-211-5p promotes neuronal apoptosis via Efemp2 inhibition. Summary statement: This study revealed the significance of sevoflurane-induced increases in miR-211-5p on the promotion of neuronal apoptosis via inhibition of Efemp2 and its downstream targets.

Prolonged Volatile Anesthetic Exposure Exacerbates Cognitive Impairment and Neuropathology in the 5xFAD Mouse Model of Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is a progressive neurodegenerative disease which shows a set of symptoms involving cognitive changes and psychological changes. Given that AD is the most common form of dementia in aging population and the increasing demand for anesthesia/surgery with aging, there has been significant interest in the exact impact of volatile anesthetics on cognitive function and pathological alterations in AD population.

OBJECTIVE

This study aimed to investigate behavioral changes and neuropathology in the 5xFAD mouse model of Alzheimer's disease with short-term exposure or long-term exposure to desflurane, sevoflurane, or isoflurane.

METHODS

In this study, we exposed 5xFAD mouse model of AD to isoflurane, sevoflurane, or desflurane in two different time periods (30 min and 6 h), and the memory related behaviors as well as the pathological changes in 5xFAD mice were evaluated 7 days after the anesthetic exposure.

RESULTS

We found that short-term exposure to volatile anesthetics did not affect hippocampus dependent memory and the amyloid-β (Aβ) deposition in the brain. However, long-term exposure to sevoflurane or isoflurane significantly increased the Aβ deposition in CA1 and CA3 regions of hippocampus, as well as the glial cell activation in amygdala. Besides, the PSD-95 expression was decreased in 5xFAD mice with exposure to sevoflurane or isoflurane and the caspase-3 activation was enhanced in isoflurane, sevoflurane, and desflurane groups.

CONCLUSION

Our results demonstrate the time-dependent effects of common volatile anesthetics and implicate that desflurane has the potential benefits to prolonged anesthetic exposure in AD patients.

Lovastatin attenuates sevoflurane-induced cognitive disorder in aged rats via reducing Aβ accumulation

As a general anesthetic widely used in surgical, sevoflurane has been shown to cause cognitive and memory deficits in the elderly. It's important to find out agents that can counteract sevoflurane-induced cognitive dysfunction. This study is aimed to investigate the effect of lovastatin on sevoflurane-induced cognitive impairment in aged rats and reveal the potential mechanisms. BV-2 cells, rat hippocampal neurons or male aged rats were exposed to 2% sevoflurane for 5 h. The cells were pretreated with 10 μM lovastatin. The rats were intraperitoneally injected with 5 mg/kg/day lovastatin for three days. The results showed that lovastatin enhanced exosomal IDE secretion from sevoflurane-exposed BV-2 cells and promoted Aβ degradation. Lovastatin treatment also inhibited the increased expressions of β-secretase 1 (BACE1) and γ-secretase in hippocampal neurons under sevoflurane exposure in vitro. In animal experiments, the discrimination index in novel object recognition test and percentage of spontaneous alternation in Y-maze test were significantly elevated after lovastatin administration. In addition, Aβ plaque area and contents of soluble Aβ1-40 and Aβ1-42 in the hippocampal tissues were decreased upon lovastatin treatment. Furthermore, lovastatin reversed sevoflurane-induced Aβ accumulation via up-regulating IDE expression, and down-regulating amyloid precursor protein (APP)-related protein expression (β-C-terminal fragment (CTF), BACE1 and γ-secretase). In conclusion, lovastatin alleviates sevoflurane-induced cognitive deficient in aged rats via promoting Aβ degradation and reducing Aβ production. Lovastatin may be beneficial in preventing anesthetic-induced cognitive impairment.

The effects of anaesthetics and sedatives on brain inflammation

Microglia are involved in many dynamic processes in the central nervous system (CNS) including the development of inflammatory processes and neuromodulation. Several sedative, analgesic or anaesthetic drugs, such as opioids, ∝2-adrenergic agonists, ketamine, benzodiazepines and propofol can cause both neuroprotective and harmful effects on the brain. The purpose of this review is to present the main findings on the use of these drugs and the mechanisms involved in microglial activation. Alpha 2-adrenergic agonists, propofol and benzodiazepines have several pro- or anti-inflammatory effects on microglia. Long-term use of benzodiazepines and propofol causes neuroapoptotic effects and α2-adrenergic agonists may attenuate these effects. Conversely, morphine and fentanyl may have proinflammatory effects, causing behavioural changes in patients and changes in cell viability in vitro. Conversely, chronic administration of morphine induces CCL5 chemokine expression in microglial cells that promotes their survival.

Anesthesia and the Developing Brain: A Review of Sevoflurane-induced Neurotoxicity in Pediatric Populations

PURPOSE

For over 150 years of anesthetic practice, it was believed that the effects of general anesthetics were temporary and not adverse. A growing number of studies over the past 2 decades, however, have identified structural and cognitive abnormalities, especially in the developing brain. Despite the growing evidence of anesthetic-induced neurotoxicity in animal studies, the evidence to date in humans has been inconsistent and unclear. Sevoflurane, a commonly used inhalational agent in pediatric anesthesia, is an agent of choice for inhalational induction due to its rapid activity and low blood-gas solubility. With evaluation of the current literature, improved considerations can be made regarding the widespread use of sevoflurane as an anesthetic.

METHODS

PubMed database was searched for article published between 1969 through 2020. The reference lists of identified articles were searched manually for additional papers eligible for inclusion. This review addressed the tolerability of sevoflurane in specific populations, particularly pediatrics, and is divided into 3 parts: (1) the history of sevoflurane use in anesthetic practice and the pharmacokinetic properties that make it advantageous in pediatric populations; (2) proposed mechanisms of anesthesia-induced neurotoxicity; and (3) considerations due to potential adverse effects of sevoflurane in both short and long procedures.

FINDINGS

There is reason for concern regarding the neurotoxic effects of sevoflurane in both the pediatric and elderly populations, as spatial memory loss, developmental deficits, and an enhanced risk for Alzheimer disease have been linked with the use of this popular inhalational agent.

IMPLICATIONS

The duration and dose of sevoflurane may need to be altered, especially in longer procedures in pediatric populations. This may change how sevoflurane is administered, thus indicating a greater demand for an understanding of its limitations as an anesthetic agent.

Gene-Specific DNA Methylation Linked to Postoperative Cognitive Dysfunction in Apolipoprotein E3 and E4 Mice

BACKGROUND

Geriatric surgical patients are at higher risk of developing postoperative neurocognitive disorders (NCD) than younger patients. The specific mechanisms underlying postoperative NCD remain unknown, but they have been linked to genetic risk factors, such as the presence of APOE4, compared to APOE3, and epigenetic modifications caused by exposure to anesthesia and surgery.

OBJECTIVE

To test the hypothesis that compared to E3 mice, E4 mice exhibit a more pronounced postoperative cognitive impairment associated with differential DNA methylation in brain regions linked to learning and memory.

METHODS

16-month-old humanized apolipoprotein-E targeted replacement mice bearing E3 or E4 were subjected to surgery (laparotomy) under general isoflurane anesthesia or sham. Postoperative behavioral testing and genome-wide DNA methylation were performed.

RESULTS

Exposure to surgery and anesthesia impaired cognition in aged E3, but not E4 mice, likely due to the already lower cognitive performance of E4 prior to surgery. Cognitive impairment in E3 mice was associated with hypermethylation of specific genes, including genes in the Ephrin pathway implicated in synaptic plasticity and learning in adults and has been linked to Alzheimer's disease. Other genes, such as the Scratch Family Transcriptional Repressor 2, were altered after surgery and anesthesia in both the E3 and E4 mice.

CONCLUSION

Our findings suggest that the neurocognitive and behavioral effects of surgery and anesthesia depend on baseline neurocognitive status and are associated with APOE isoform-dependent epigenetic modifications of specific genes and pathways involved in memory and learning.

Association Between Exposure to General Versus Regional Anesthesia and Risk of Dementia in Older Adults

BACKGROUND/OBJECTIVES

Cognitive changes are commonly observed in older adults following surgical procedures. There are concerns that exposure to general anesthesia (GA) may contribute to an increased risk of Alzheimer's disease. Our study examined the associations between exposure to GA compared with regional anesthesia (RA) administered for elective surgical procedures and the development of dementia.

DESIGN

Population-based propensity matched retrospective cohort study.

SETTING

Linked administrative databases were accessed from ICES (formerly called the Institute for Clinical Evaluative Services) in Ontario, Canada.

PARTICIPANTS

We included all community-dwelling individuals aged 66 and older who underwent one of five elective surgical procedures in Ontario, Canada, between April 1, 2007, and March 31, 2011. Individuals with evidence of dementia preceding cohort entry were excluded. Individuals who received GA were matched within surgical procedures to those who received RA on age, sex, cohort entry year, and a propensity score to control for potential confounders.

MEASUREMENTS

The baseline characteristics of the study sample were compared before and after matching. Individuals were followed for up to 5 years following cohort entry for the occurrence of dementia using a validated algorithm. Cox proportional hazards analysis was used to determine the hazard ratio (HR) and 95% confidence interval (CI) for the association between anesthetic type and dementia. Subgroup and sensitivity analyses were undertaken.

RESULTS

A total of 7,499 matched pairs were included in the final analysis. Overall, no difference was observed in the risk of being diagnosed with dementia for individuals who received GA when compared with RA (HR = 1.0; 95% CI = .8-1.2). There was also no association between anesthesia and dementia in most subgroup and sensitivity analyses.

CONCLUSION

Elective surgery using GA was not associated with an overall elevated risk of dementia when compared with RA. Future studies are required to determine whether surgery is a risk factor for dementia irrespective of anesthetic technique.

Perioperative brain health: strategies to prevent perioperative neurocognitive disorders

Cognitive changes in patients after anesthesia and surgery have been recognized for over 100 years. Research on postoperative cognitive changes accelerated in the 1980s and the term postoperative cognitive dysfunction emerged, which was used until recently. Postoperative cognitive dysfunction has been used in research to describe an objectively measurable decline in cognitive function using neuropsychological tests. This dysfunction had significant heterogeneity in the type, number of tests, timing of tests, and the criteria for change. Therefore, a recent article recommended a new nomenclature for perioperative neurocognitive disorders including neurocognitive disorder, postoperative delirium, delayed neurocognitive recovery, and postoperative neurocognitive disorder. Since old age and baseline cognitive impairment are important risk factors for these perioperative neurocognitive disorders, routine preoperative cognitive assessment in all elderly patients is recommended. A preventive strategy is important, since effective modality for the treatment of perioperative neurocognitive disorders is not yet known. Intraoperative monitoring of age-adjusted end-tidal minimal alveolar concentration fraction, electroencephalography-based anesthetic management, and perioperative non-pharmacological methods are recommended for effective prevention.

Exposure to surgery with general anaesthesia during adult life is not associated with increased brain amyloid deposition in older adults

BACKGROUND

Exposure to surgery with general anaesthesia (surgery/GA) is associated with cortical atrophy, but the aetiology remains unknown. Amyloid-β (Aβ) deposition is one of the hallmark pathological characteristics of Alzheimer's disease (AD). We examined brain Aβ burden in study participants exposed to surgery/GA.

METHODS

We performed a cross-sectional analysis of residents of Olmsted County, MN, USA, in the Mayo Clinic Study of Aging who were aged 70-97 yr and underwent measurement of (i) brain Aβ with Pittsburgh compound B positron emission tomography (PiB PET), (ii) brain glucose metabolism with 18-fluorodeoxyglucose (FDG) PET, and (iii) temporal cortical thickness with MRI. Separate analyses were performed with exposure to surgery/GA, defined as occurring after age 40 yr, and with exposure to surgery/GA, defined as occurring within 20 yr before neuroimaging. Imaging measurements were compared between participants who were exposed to surgery/GA vs not exposed.

RESULTS

Of the 2563 participants, 585 had PET scans. Regardless of the definition used to quantify exposure, no significant associations were detected between exposure and either global PiB PET or FDG PET. In contrast, exposure to surgery/GA was associated with an increased likelihood of abnormal cortical thinning: odds ratio (OR)=1.98 (95% confidence interval [CI]: 1.19-3.31); P=0.010 in those exposed after age 40 yr, and OR=1.64 (95% CI: 1.05-2.55); P=0.029 in those exposed in the prior 20 yr.

CONCLUSIONS

Exposure to surgery/GA is not associated with increases in cortical amyloid deposition. This finding suggests that the modest cortical thinning associated with surgery/GA is not related to AD pathology, but rather is caused by other processes.

Impact of Sevoflurane Versus Propofol Anesthesia on Post-Operative Cognitive Dysfunction in Elderly Cancer Patients: A Double-Blinded Randomized Controlled Trial

Background

Research on the clinical outcomes of surgical patients anaesthetized with sevoflurane and the association of sevoflurane with post-operative cognitive dysfunction (POCD) is scarce. We evaluated whether sevoflurane-based anesthesia increased the incidence of POCD and worsened prognosis compared to propofol-based anesthesia in elderly cancer patients.

Material/Methods

This single-center, prospective, double-blind randomized controlled trial included 234 patients aged 65 to 86 years undergoing tumor resection who received sevoflurane-based (Group S) or propofol-based (Group P) anesthesia during surgery. A series of neuropsychological tests was performed to evaluate cognitive function before surgery and at 7 days and 3 months post-operation, and the results were compared to those of healthy controls.

Results

At 7 days post-operation there were no significant differences in the incidence of POCD between patients who received sevoflurane-based or propofol-based anesthesia during surgery: Group S was at 29.1% (32 out of 110 patients) versus Group P at 27.3% (30 out of 110), P=0.764. At 3 months, Group S was at 11.3% (12 out of 106 patients) versus Group P at 9.2% (10 out of 109), P=0.604. During the first 2 days post-operation, the QoR-40 global score was significantly lower in Group S compared to Group P [POD 1: P=0.004; POD 2: P=0.001]. There were no significant differences in in-hospital post-operative complications, post-operative length of hospital stay, all-cause mortality at 30 days, and 3 months post-operation, or post-operative quality of life at 3 months between patients in Group S and Group P.

Conclusions

Sevoflurane-based anesthesia did not increase the incidence of POCD compared to propofol-based anesthesia at 7 days or 3 months post-operation or impact short-term post-operative prognosis.

Influence of propofol-based total intravenous anaesthesia on peri-operative outcome measures: a narrative review

Propofol-based total intravenous anaesthesia is well known for its smooth, clear-headed recovery and anti-emetic properties, but there are also many lesser known beneficial properties that can potentially influence surgical outcome. We will discuss the anti-oxidant, anti-inflammatory and immunomodulatory effects of propofol and their roles in pain, organ protection and immunity. We will also discuss the use of propofol in cancer surgery, neurosurgery and older patients.

Anesthesiology and cognitive impairment: a narrative review of current clinical literature

Background

The impact of general anesthesia on cognitive impairment is controversial and complex. A large body of evidence supports the association between exposure to surgery under general anesthesia and development of delayed neurocognitive recovery in a subset of patients. Existing literature continues to debate whether these short-term effects on cognition can be attributed to anesthetic agents themselves, or whether other variables are causative of the observed changes in cognition. Furthermore, there is conflicting data on the relationship between anesthesia exposure and the development of long-term neurocognitive disorders, or development of incident dementia in the patient population with normal preoperative cognitive function. Patients with pre-existing cognitive impairment present a unique set of anesthetic considerations, including potential medication interactions, challenges with cooperation during assessment and non-general anesthesia techniques, and the possibility that pre-existing cognitive impairment may impart a susceptibility to further cognitive dysfunction.

Main body

This review highlights landmark and recent studies in the field, and explores potential mechanisms involved in perioperative cognitive disorders (also known as postoperative cognitive dysfunction, POCD). Specifically, we will review clinical and preclinical evidence which implicates alterations to tau protein, inflammation, calcium dysregulation, and mitochondrial dysfunction. As our population ages and the prevalence of Alzheimer’s disease and other forms of dementia continues to increase, we require a greater understanding of potential modifiable factors that impact perioperative cognitive impairment.

Conclusions

Future research should aim to further characterize the associated risk factors and determine whether certain anesthetic approaches or other interventions may lower the potential risk which may be conferred by anesthesia and/or surgery in susceptible individuals.

Cistanches alleviates sevoflurane-induced cognitive dysfunction by regulating PPAR-γ-dependent antioxidant and anti-inflammatory in rats

This study aimed to investigate the protective effects and underlying mechanisms of cistanche on sevoflurane‐induced aged cognitive dysfunction rat model. Aged (24 months) male SD rats were randomly assigned to four groups: control group, sevoflurane group, control + cistanche and sevoflurane + cistanche group. Subsequently, inflammatory cytokine levels were measured by ELISA, and the cognitive dysfunction of rats was evaluated by water maze test, open‐field test and the fear conditioning test. Three days following anaesthesia, the rats were killed and hippocampus was harvested for the analysis of relative biomolecules. The oxidative stress level was indicated as nitrite and MDA concentration, along with the SOD and CAT activity. Finally, PPAR‐γ antagonist was used to explore the mechanism of cistanche in vivo. The results showed that after inhaling the sevoflurane, 24‐ but not 3‐month‐old male SD rats developed obvious cognitive impairments in the behaviour test 3 days after anaesthesia. Intraperitoneal injection of cistanche at the dose of 50 mg/kg for 3 consecutive days before anaesthesia alleviated the sevoflurane‐induced elevation of neuroinflammation levels and significantly attenuated the hippocampus‐dependent memory impairments in 24‐month‐old rats. Cistanche also reduced the oxidative stress by decreasing nitrite and MDA while increasing the SOD and CAT activity. Moreover, such treatment also inhibited the activation of microglia. In addition, we demonstrated that PPAR‐γ inhibition conversely alleviated cistanche‐induced protective effect. Taken together, we demonstrated that cistanche can exert antioxidant, anti‐inflammatory, anti‐apoptosis and anti‐activation of microglia effects on the development of sevoflurane‐induced cognitive dysfunction by activating PPAR‐γ signalling.

Exposure to surgery under general anaesthesia and brain magnetic resonance imaging changes in older adults

BACKGROUND

Preclinical studies suggest that exposure to general anaesthesia (GA) could cause neurodegeneration consistent with Alzheimer's disease (AD) pathology. Brain magnetic resonance imaging (MRI) is useful to study structural brain changes. We tested the hypothesis that exposure to surgery with GA (surgery/GA) is associated with greater cortical thinning and increased frequency of white matter lesions.

METHODS

This is a cross-sectional analysis of 70-91-yr-old participants enrolled in the Mayo Clinic Study of Aging who had baseline MRI. The thickness of selected cortical regions, the volume of white matter hyperintensities, and the frequency of cortical infarctions were compared in participants who were and were not exposed to surgery/GA within 20 yr before the first MRI obtained after enrolment.

RESULTS

Of 1410 participants with MRI scans, 932 were exposed to surgery/GA before scanning. In adjusted analyses, cortical thickness in regions vulnerable to AD was significantly less in those exposed to surgery/GA in the prior 20 yr (difference -0.023 mm, [95% confidence interval (CI) -0.041 to -0.005], P=0.014). Those with surgery in the prior 20 yr were more likely to have 'abnormal thickness' compared with those without surgery (odds ratio=1.45, [95% CI 1.10-1.90], P=0.009). Exposure was not associated with white matter hyperintensities or the presence of brain infarcts.

CONCLUSIONS

This study suggests that exposure of older adults to surgical anaesthesia is associated with thinning in cortical regions implicated in AD. The pathogenesis and mechanisms driving these neurodegenerative changes, and the potential clinical significance of these findings, require further study.

Cognitive function after surgery with regional or general anesthesia: A population-based study

INTRODUCTION

Our aim was to examine whether surgery with regional anesthesia (RA) is associated with accelerated long-term cognitive decline comparable with that previously reported after general anesthesia (GA).

METHODS

Longitudinal cognitive function was analyzed in a cohort of 1819 older adults. Models assessed the rate of change in global and domain-specific cognition over time in participants exposed to RA or GA.

RESULTS

When compared with those unexposed to anesthesia, the postoperative rate of change of the cognitive global z-score was greater in those exposed to both RA (difference in annual decline of -0.041, P = .011) and GA (-0.061, P < .001); these rates did not differ. In analysis of the domain-specific scores, an accelerated decline in memory was observed after GA (-0.065, P < .001) but not RA (-0.011, P = .565).

CONCLUSIONS

Older adults undergoing surgery with RA experience decline of global cognition similar to those receiving GA; however, memory was not affected.

Exposure to General Anesthesia and Risk of Dementia: A Nationwide Population-Based Cohort Study

BACKGROUND

There is a growing concern that general anesthesia could increase the risk of dementia. However, the relationship between anesthesia and subsequent dementia is still undetermined.

OBJECTIVE

To determine whether the risk of dementia increases after exposure to general anesthesia.

METHODS

A population-based prospective cohort study analyzing the Korean National Health Insurance Service-National Sample Cohort database was conducted of all persons aged over 50 years (n = 219,423) from 1 January 2003 and 31 December 2013.

RESULTS

44,956 in the general anesthesia group and 174,469 in the control group were followed for 12 years. The risk of dementia associated with previous exposure to general anesthesia was increased after adjusting for all covariates such as gender, age, health care visit frequency, and co-morbidities (Hazard ratio = 1.285, 95% confidence interval = 1.262-1.384, time-varying Cox hazard model). In addition, the number of anesthetic agents administered, the number of exposures to general anesthesia, the cumulative exposure time, and the organ category involved in surgery were associated with risk of dementia.

CONCLUSION

In light of the increasing societal burden of dementia, careful surveillance for dementia and prevention guidelines for patients after general anesthesia are needed.

Histone Deacetylase Inhibitor MS-275 Alleviates Postoperative Cognitive Dysfunction in Rats by Inhibiting Hippocampal Neuroinflammation

Neuroinflammation in the hippocampus plays essential roles in postoperative cognitive dysfunction (POCD). Histone deacetylases (HDACs) have recently been identified as key regulators of neuroinflammation. MS-275, an inhibitor of HDAC, has been reported to have neuroprotective effects. Therefore, the present study aimed to test the hypothesis that pretreatment with MS-275 prevents POCD by inhibiting neuroinflammation in rats. In this study, anesthesia/surgery impaired cognition, demonstrated by an increase escape latency and reduction in the number of platform crossings in Morris water maze (MWM) trials, through activating microglia neuroinflammation and decreasing PSD-95 expression. However, pretreatment with MS-275 attenuated postoperative cognitive impairment severity. Furthermore, pretreatment with MS-275 decreased activated microglia levels and increased PSD95 protein expression in the hippocampus. Pretreatment with MS-275 reduced NF-κB-p65 protein expression and nuclear accumulation as well as the neuroinflammatory response (production of proinflammatory cytokines including TNF-α and IL-1β) in the hippocampus. Additionally, MS-275 reduced HDAC2 expression and HDAC activity in the hippocampus, which were enhanced in vehicle-treated rats. These results suggest that MS-275 alleviates postoperative cognitive dysfunction by reducing neuroinflammation in the hippocampus of rats via HDAC inhibition.

General Anesthetic Use in Fragile X Spectrum Disorders

The fragile X premutation is characterized by a repeat expansion mutation (between 55 to 200 CGG repeats) in the fragile X mental retardation 1 (FMR1) gene, which leads to RNA toxicity at the cellular level. This may cause patients with the premutation to be particularly susceptible to environmental toxins, which could manifest clinically as new or worsening ataxia and memory loss. Multiple published case reports have also suggested general anesthetics as a potential toxin leading to negative side effects when used in patients with fragile X-associated disorders. However, at this time, there have been no formal research studies regarding cellular changes or long-term clinical manifestations after general anesthetic use in this population. This review aims to highlight previous case reports regarding sequelae related to general anesthetic use in fragile X-associated disorders. New case reports related to this phenomenon are also included.

Postoperative cognitive dysfunction after sevoflurane or propofol general anaesthesia in combination with spinal anaesthesia for hip arthroplasty

It is unknown if the type of general anaesthetic used for maintenance of anaesthesia affects the incidence of postoperative cognitive dysfunction (POCD). The aim of this study was to compare the incidence of POCD in patients administered either sevoflurane or propofol for maintenance of anaesthesia during total hip replacement surgery. Following administration of a spinal anaesthetic, patients received either sevoflurane (n=121) or propofol (n=171) at the discretion of the anaesthetist for maintenance of general anaesthesia to maintain the processed electroencephalogram (bispectral index, BIS) under 60. POCD was assessed postoperatively at day 7, three months, and 12 months using a neurocognitive test battery. There was no statistically significant difference between the incidence of POCD at any timepoint with sevoflurane compared to propofol. The mean BIS was significantly lower in the sevoflurane group than in the propofol group (mean BIS 44.3 [standard deviation, SD 7.5] in the sevoflurane group versus 53.7 [SD 8.1] in the propofol group, <i>P</i>=0.0001). However, there was no statistically significant association between intraoperative BIS level and the incidence of POCD at any timepoint. Our results suggest that the incidence of POCD is not strongly influenced by the type of anaesthesia used in elderly patients.

Effects of propofol and surgery on neuropathology and cognition in the 3xTgAD Alzheimer transgenic mouse model

Background

Previous work suggests that anaesthesia and surgery amplify the pathology and cognitive impairment of animals made vulnerable via age or specific transgenes. We hypothesized that surgery under propofol anaesthesia, a widely used i.v. general anaesthetic, has minimal delayed cognitive and neuroinflammatory sequelae in a vulnerable mouse transgenic model.

Methods

We conducted caecal ligation and excision surgery in cognitively presymptomatic (11-month-old) 3xTgAD mice under i.p. propofol anaesthesia. Age-matched 3xTgAD control mice received vehicle or propofol without surgery. Morris water maze testing was conducted 3 and 15 weeks later. Brains were examined with quantitative immunohistochemistry for amyloid β plaques, tau pathology, and microglial activation. Acute changes in neuroinflammatory cytokines were assessed in separate cohorts at 6 h.

Results

We detected no significant differences between groups in escape latencies at either 3 or 15 weeks, but detected a significant effect of surgery in the probe test at both 3 and 15 weeks. Spatial working memory was unaffected at 16 weeks in any group. No effects of either propofol alone or propofol with surgery were detected on plaque formation, tau aggregates, or neuroinflammation. Acute biochemical assays detected no effects in brain interleukin-10 or interleukin-6 concentrations.

Conclusions

Surgery in a vulnerable transgenic mouse under propofol anaesthesia was associated with minimal to no changes in short- and long-term behaviour and no changes in neuropathology. This suggests that propofol anaesthesia is associated with better cognitive outcomes in the aged, vulnerable brain compared with inhalation anaesthesia.

Intravenous versus inhalational maintenance of anaesthesia for postoperative cognitive outcomes in elderly people undergoing non-cardiac surgery

BACKGROUND

The use of anaesthetics in the elderly surgical population (more than 60 years of age) is increasing. Postoperative delirium, an acute condition characterized by reduced awareness of the environment and a disturbance in attention, typically occurs between 24 and 72 hours after surgery and can affect up to 60% of elderly surgical patients. Postoperative cognitive dysfunction (POCD) is a new-onset of cognitive impairment which may persist for weeks or months after surgery.Traditionally, surgical anaesthesia has been maintained with inhalational agents. End-tidal concentrations require adjustment to balance the risks of accidental awareness and excessive dosing in elderly people. As an alternative, propofol-based total intravenous anaesthesia (TIVA) offers a more rapid recovery and reduces postoperative nausea and vomiting. Using TIVA with a target controlled infusion (TCI) allows plasma and effect-site concentrations to be calculated using an algorithm based on age, gender, weight and height of the patient.TIVA is a viable alternative to inhalational maintenance agents for surgical anaesthesia in elderly people. However, in terms of postoperative cognitive outcomes, the optimal technique is unknown.

OBJECTIVES

To compare maintenance of general anaesthesia for elderly people undergoing non-cardiac surgery using propofol-based TIVA or inhalational anaesthesia on postoperative cognitive function, mortality, risk of hypotension, length of stay in the postanaesthesia care unit (PACU), and hospital stay.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 11), MEDLINE (1946 to November 2017), Embase (1974 to November 2017), PsycINFO (1887 to November 2017). We searched clinical trials registers for ongoing studies, and conducted backward and forward citation searching of relevant articles.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) with participants over 60 years of age scheduled for non-cardiac surgery under general anaesthesia. We planned to also include quasi-randomized trials. We compared maintenance of anaesthesia with propofol-based TIVA versus inhalational maintenance of anaesthesia.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion, extracted data, assessed risk of bias, and synthesized findings.

MAIN RESULTS

We included 28 RCTs with 4507 randomized participants undergoing different types of surgery (predominantly cardiovascular, laparoscopic, abdominal, orthopaedic and ophthalmic procedures). We found no quasi-randomized trials. Four studies are awaiting classification because we had insufficient information to assess eligibility.All studies compared maintenance with propofol-based TIVA versus inhalational maintenance of anaesthesia. Six studies were multi-arm and included additional TIVA groups, additional inhalational maintenance or both. Inhalational maintenance agents included sevoflurane (19 studies), isoflurane (eight studies), and desflurane (three studies), and was not specified in one study (reported as an abstract). Some studies also reported use of epidural analgesia/anaesthesia, fentanyl and remifentanil.We found insufficient reporting of randomization methods in many studies and all studies were at high risk of performance bias because it was not feasible to blind anaesthetists to study groups. Thirteen studies described blinding of outcome assessors. Three studies had a high of risk of attrition bias, and we noted differences in the use of analgesics between groups in six studies, and differences in baseline characteristics in five studies. Few studies reported clinical trials registration, which prevented assessment of risk of selective reporting bias.We found no evidence of a difference in incidences of postoperative delirium according to type of anaesthetic maintenance agents (odds ratio (OR) 0.59, 95% confidence interval (CI) 0.15 to 2.26; 321 participants; five studies; very low-certainty evidence); we noted during sensitivity analysis that using different time points in one study may influence direction of this result. Thirteen studies (3215 participants) reported POCD, and of these, six studies reported data that could not be pooled; we noted no difference in scores of POCD in four of these and in one study, data were at a time point incomparable to other studies. We excluded one large study from meta-analysis because study investigators had used non-standard anaesthetic management and this study was not methodologically comparable to other studies. We combined data for seven studies and found low-certainty evidence that TIVA may reduce POCD (OR 0.52, 95% CI 0.31 to 0.87; 869 participants).We found no evidence of a difference in mortality at 30 days (OR 1.21, 95% CI 0.33 to 4.45; 271 participants; three studies; very low-certainty evidence). Twelve studies reported intraoperative hypotension. We did not perform meta-analysis for 11 studies for this outcome. We noted visual inconsistencies in these data, which may be explained by possible variation in clinical management and medication used to manage hypotension in each study (downgraded to low-certainty evidence); one study reported data in a format that could not be combined and we noted little or no difference between groups in intraoperative hypotension for this study. Eight studies reported length of stay in the PACU, and we did not perform meta-analysis for seven studies. We noted visual inconsistencies in these data, which may be explained by possible differences in definition of time points for this outcome (downgraded to very low-certainty evidence); data were unclearly reported in one study. We found no evidence of a difference in length of hospital stay according to type of anaesthetic maintenance agent (mean difference (MD) 0 days, 95% CI -1.32 to 1.32; 175 participants; four studies; very low-certainty evidence).We used the GRADE approach to downgrade the certainty of the evidence for each outcome. Reasons for downgrading included: study limitations, because some included studies insufficiently reported randomization methods, had high attrition bias, or high risk of selective reporting bias; imprecision, because we found few studies; inconsistency, because we noted heterogeneity across studies.

AUTHORS' CONCLUSIONS

We are uncertain whether maintenance with propofol-based TIVA or with inhalational agents affect incidences of postoperative delirium, mortality, or length of hospital stay because certainty of the evidence was very low. We found low-certainty evidence that maintenance with propofol-based TIVA may reduce POCD. We were unable to perform meta-analysis for intraoperative hypotension or length of stay in the PACU because of heterogeneity between studies. We identified 11 ongoing studies from clinical trials register searches; inclusion of these studies in future review updates may provide more certainty for the review outcomes.

General anesthesia combined with epidural anesthesia on the postoperative cognitive functions in pregnant women with dystocia

Effects of general anesthesia combined with epidural anesthesia on the postoperative cognitive functions in pregnant women with dystocia were investigated. Postoperative cognitive functions of 84 dystocia pregnant women treated with cesarean section were retrospectively analyzed. Patients who received general anesthesia were included in group A (n=42), and those who received general anesthesia combined with epidural anesthesia were included in group B (n=42). Mean arterial pressure (MAP), heart rate (HR) and bispectral index (BIS) at different time-points after anesthesia in the two groups of patients were observed and compared. Recovery of anesthesia such as the recovery time of spontaneous breathing, recovery time of orientation and time of eye opening were observed and compared between two groups of patients. Mini mental state examination (MMSE) scores were obtained and compared between the the groups of patients at different time-points after operation. Three vital signs (MAP, HR and BIS) were not significantly different between group A and B at the same time-point (P>0.05) and the maintenance of anesthesia was satisfactory. Compared with group A, postoperative recovery time of spontaneous breathing, recovery time of orientation and the time of eye opening in group B were all significantly shorter (P<0.05). In addition, MMSE scores of patients in group B, 2 and 12 h after operation were 24.33±1.61 and 26.41±1.83 points, respectively, which were significantly improved compared with those of patients in group A (20.45±1.58 and 22.39±1.72 points, respectively) (P<0.05). In conclusion, recovery of postoperative cognitive functions in pregnant women with dystocia who received general anesthesia combined with epidural anesthesia was shorter to that of those who only received general anesthesia.

Association between exposure to anaesthesia and surgery and long-term cognitive trajectories in older adults: report from the Mayo Clinic Study of Aging

BACKGROUND

The link between exposure to general anaesthesia and surgery (exposure) and cognitive decline in older adults is debated. We hypothesised that it is associated with cognitive decline.

METHODS

We analysed the longitudinal cognitive function trajectory in a cohort of older adults. Models assessed the rate of change in cognition over time, and its association with exposure to anaesthesia and surgery. Analyses assessed whether exposure in the 20 yr before enrolment is associated with cognitive decline when compared with those unexposed, and whether post-enrolment exposure is associated with a change in cognition in those unexposed before enrolment.

RESULTS

We included 1819 subjects with median (25th and 75th percentiles) follow-up of 5.1 (2.7-7.6) yr and 4 (3-6) cognitive assessments. Exposure in the previous 20 yr was associated with a greater negative slope compared with not exposed (slope: -0.077 vs -0.059; difference: -0.018; 95% confidence interval: -0.032, -0.003; P=0.015). Post-enrolment exposure in those previously unexposed was associated with a change in slope after exposure (slope: -0.100 vs -0.059 for post-exposure vs pre-exposure, respectively; difference: -0.041; 95% confidence interval: -0.074, -0.008; P=0.016). Cognitive impairment could be attributed to declines in memory and attention/executive cognitive domains.

CONCLUSIONS

In older adults, exposure to general anaesthesia and surgery was associated with a subtle decline in cognitive z-scores. For an individual with no prior exposure and with exposure after enrolment, the decline in cognitive function over a 5 yr period after the exposure would be 0.2 standard deviations more than the expected decline as a result of ageing. This small cognitive decline could be meaningful for individuals with already low baseline cognition.

Mesenchymal stromal cells attenuate sevoflurane-induced apoptosis in human neuroglioma H4 cells

BACKGROUND

Inhalation of sevoflurane can induce neuronal apoptosis, cognitive impairment and abnormal behaviors. Bone marrow mesenchymal stem cells (MSCs) can secret neurotrophic factors and cytokines to protect from oxidative stress-related neuronal apoptosis. However, whether MSCs can protect from sevoflurane-induced neuronal apoptosis and the potential mechanisms are unclear.

METHODS

A non-contact co-culture of MSCs with human neuroglioma H4 cells (H4 cells) was built. H4 cells were co-cultured with MSCs or without MSCs (control) for 24 h. The co-cultured H4 cells were exposed to 4% sevoflurane for 6 h. The levels of caspase-3, reactive oxygen species (ROS), adenosine triphosphate (ATP), and the release of cytochrome C were determined by Western blot and fluorescence assay.

RESULTS

Sevoflurane exposure significantly elevated the levels of cleaved caspase 3 and Bax in H4 cells. However, these phenomena were significantly offset by the co-culture with MSCs in H4 cells. Co-culture with MSCs before, but not after, sevoflurane exposure, significantly attenuated sevoflurane-induced ROS production in H4 cells. MSCs prevented sevoflurane-mediated release of cytochrome C from the mitochondria and production of ATP in H4 cells.

CONCLUSIONS

Our study indicated that soluble factors secreted by MSCs attenuated the sevoflurane-induced oxidative stress and apoptosis of neuronal cells by preserving their mitochondrial function.

Repeat propofol anesthesia does not exacerbate plaque deposition or synapse loss in APP/PS1 Alzheimer's disease mice

Background

There is increasing interest in whether anesthetic agents affect the risk or progression of Alzheimer’s disease (AD). To mitigate many of the methodological issues encountered in human retrospective cohort studies we have used a transgenic model of AD to investigate the effect of propofol on AD pathology.

Methods

Six month-old amyloid precursor protein/presenilin 1 (APP/PS1) transgenic AD mice and control mice were exposed to 3 doses of propofol (200 mg/kg) or vehicle, delivered at monthly intervals.

Results

There was no difference in the extent of β-amyloid (Aβ) immunolabeled plaque deposition in APP/PS1 mice in vehicle versus propofol treatment groups. We also detected no difference in plaque-associated synapse loss in APP/PS1 mice following repeat propofol exposure relative to vehicle. Western blotting indicated that there was no difference in post-synaptic density protein 95, synaptophysin or glutamic acid decarboxylase 65/67 expression in control or APP/PS1 mice subjected to repeat propofol treatment relative to vehicle.

Conclusions

These data suggest that repeat propofol anesthesia may not exacerbate plaque deposition or associated synapse loss in AD. Interestingly, this data also provides some of the first evidence suggesting that repeat propofol exposure in adult wild-type mice does not result in robust long-term alterations in the levels of key excitatory and inhibitory synaptic markers.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0509-5) contains supplementary material, which is available to authorized users.

Anesthesia and the risk of dementia in the elderly

Cognitive complications are common after surgery in the elderly, and with an increased number of elderly patients undergoing surgery, a potential impact of anaesthesia and surgery on long term cognition, and especially dementia would be concerning. The question whether anaesthesia and surgery in itself induce structural changes in the brain and thereby cognitive deterioration, or reveal a preexisting cognitive impairment remains unresolved. Several studies show an increased risk of reversible cognitive impairment after surgery in the elderly, but the risk of inducing dementia remains speculative. Further studies are needed to elucidate this potential association. Meanwhile, elderly frail patients need to be closely followed including preoperative cognitive screening, since they are at increased risk of cognitive deterioration after surgery and discharge.

Anesthesia and Alzheimer disease – Current perceptions

Background and objectives

It has been speculated that the use of anesthetic agents may be a risk factor for the development of Alzheimer disease. The objective of this review is to describe and discuss pre-clinical and clinical data related to anesthesia and this disease.

Content

Alzheimer disease affects about 5% of the population over 65 years old, with age being the main risk factor and being associated with a high morbidity. Current evidence questions a possible association between anesthesia, surgery, and long-term cognitive effects, including Alzheimer disease. Although data from some animal studies suggest an association between anesthesia and neurotoxicity, this link remains inconclusive in humans. We performed a review of the literature in which we selected scientific articles in the PubMed database, published between 2005 and 2016 (one article from 1998 due to its historical relevance), in English, which address the possible relationship between anesthesia and Alzheimer disease. 49 articles were selected.

Conclusion

The possible relationship between anesthetic agents, cognitive dysfunction, and Alzheimer disease remains to be clarified. Prospective cohort studies or randomized clinical trials for a better understanding of this association will be required.

Effect of sugammadex versus neostigmine/atropine combination on postoperative cognitive dysfunction after elective surgery

This study aimed to assess the effects of sugammadex and neostigmine/atropine on postoperative cognitive dysfunction (POCD) in adult patients after elective surgery. A randomised, double-blind controlled trial was carried out on 160 American Society of Anesthesiologists physical status I to III patients who were >40 years. The Mini-Mental State Evaluation, clock-drawing test and the Isaacs Set test were used to assess cognitive function at three timepoints: 1) preoperatively, 2) one hour postoperatively, and 3) at discharge. The anaesthetic protocol was the same for all patients, except for the neuromuscular block reversal, which was administered by random allocation using either sugammadex or neostigmine/atropine after the reappearance of T2 in the train-of-four sequence. POCD was defined as a decline ≥1 standard deviation in ≥2 cognitive tests. The incidence of POCD was similar in both groups at one hour postoperatively and at discharge (28% and 10%, in the neostigmine group, 23% and 5.4% in the sugammadex group, P=0.55 and 0.27 respectively). In relation to individual tests, a significant decline of clock-drawing test in the neostigmine group was observed at one hour postoperatively and at discharge. For the Isaacs Set test, a greater decline was found in the sugammadex group. These findings suggest that there are no clinically important differences in the incidence of POCD after neostigmine or sugammadex administration.

Anesthetic Isoflurane or Desflurane Plus Surgery Differently Affects Cognitive Function in Alzheimer's Disease Transgenic Mice

Anesthesia/surgery could be associated with cognitive impairment and Alzheimer's disease neuropathogenesis. However, whether surgery under different anesthetics has different effects on cognitive function remains largely unknown. We therefore set out to compare effects of anesthetic isoflurane or desflurane plus surgery on cognitive function and hippocampus levels of synaptic marker (postsynaptic density-95 and synaptophysin) and ATP. Five-month-old AD Transgenic (Tg) (FAD5X) and wild-type male mice received isoflurane or desflurane plus abdominal surgery. We assessed cognitive function in Barnes maze and measured hippocampus levels of postsynaptic density-95, synaptophysin, and ATP in the mice. We determined whether vitamin K₂ could mitigate these anesthesia/surgery-induced changes. Isoflurane, but not desflurane, plus surgery increased escape latency and escape distance in Barnes maze probe test and reduced postsynaptic density-95, synaptophysin, and ATP levels as compared to control condition in AD Tg mice. Vitamin K₂ attenuated the anesthesia/surgery-induced changes in the AD Tg mice. These findings suggest that isoflurane, but not desflurane, plus surgery might induce cognitive impairment via causing brain energy deficits. Pending confirmative studies in both animals and humans suggest desflurane could be a better choice for AD patients when surgery is needed. Moreover, vitamin K₂ could treat cognitive deficiency associated with anesthesia and surgery.