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

Characterizing cancer-related cognitive impairments and impact on quality of life in women with metastatic breast cancer

PURPOSE

Little is known about cancer-related cognitive impairments (CRCI) in women with metastatic breast cancer (MBC). The purpose of this study is to (1) comprehensively describe CRCI and any associated psychosocial and behavioral symptoms, (2) determine observable sociodemographic and clinical risk factors for CRCI, and (3) explore cognitive and psychosocial predictors of quality of life and social functioning in women living with MBC.

METHODS

Using a cross-sectional design, women with MBC completed assessments (objective and subjective measures of CRCI including 3 open-ended questions, measures of psychosocial and behavioral factors, and assessments of quality of life and social function), and data were analyzed using descriptive statistics, qualitative content analysis, correlation analyses, t tests, analysis of variance, and linear regression models.

RESULTS

Data from 52 women were analyzed. 69.2% of the sample reported clinically significant CRCI and 46% of the sample scored < 1 standard deviation below the standardized mean on one or more cognitive tests. Those with triple-negative MBC (compared to HER2+), recurrent MBC (compared to de novo), and no history of chemotherapy had worse subjective CRCI, and those without history of surgery and older age had worse objective CRCI. Subjective CRCI, but not objective CRCI, was significantly associated with quality of life and social functioning.

CONCLUSION

Subjective and objective CRCI are likely a common problem for those with MBC. Subjective CRCI is associated with poorer quality of life and lower social functioning. Healthcare providers should acknowledge cognitive symptoms, continually assess cognitive function, and address associated unmet needs across the MBC trajectory.

Association between surgical admissions, cognition, and neurodegeneration in older people: a population-based study from the UK Biobank

BACKGROUND

Previous studies have shown that major surgical and medical hospital admissions are associated with cognitive decline in older people (aged 40-69 years at recruitment), which is concerning for patients and caregivers. We aimed to validate these findings in a large cohort and investigate associations with neurodegeneration using MRI.

METHODS

For this population-based study, we analysed data from the UK Biobank collected from March 13, 2006, to July 16, 2023, linked to the National Health Service Hospital Episode Statistics database, excluding participants with dementia diagnoses. We constructed fully adjusted models that included age, time, sex, Lancet Commission dementia risk factors, stroke, and hospital admissions with a participant random effect. Primary outcomes were hippocampal volume and white matter hyperintensities, both of which are established markers of neurodegeneration, and exploratory analyses investigated the cortical thickness of Desikan-Killiany-Tourville atlas regions. The main cognitive outcomes were reaction time, fluid intelligence, and prospective and numeric memory. Surgeries were calculated cumulatively starting from 8 years before the baseline evaluation.

FINDINGS

Of 502 412 participants in the UK Biobank study, 492 802 participants were eligible for inclusion in this study, of whom 46 706 underwent MRI. Small adverse associations with cognition were found per surgery: reaction time increased by 0·273 ms, fluid intelligence score decreased by 0·057 correct responses, prospective memory (scored as correct at first attempt) decreased (odds ratio 0·96 [95% CI 0·95 to 0·97]), and numeric memory maximum correct matches decreased by 0·025 in fully adjusted models. Surgeries were associated with smaller hippocampal volume (β=-5·76 mm³ [-7·89 to -3·64]) and greater white matter hyperintensities volume (β=100·02 mm³ [66·17 to 133·87]) in fully adjusted models. Surgeries were also associated with neurodegeneration of the insula and superior temporal cortex.

INTERPRETATION

This population-based study corroborates that surgeries are generally safe but cumulatively are associated with cognitive decline and neurodegeneration. Perioperative brain health should be prioritised for older and vulnerable patients, particularly those who have multiple surgical procedures.

FUNDING

The Australian and New Zealand College of Anaesthetists (ANZCA) Foundation and the University of Sydney.

Low-grade Urothelial Carcinoma Recurs at a Tempo that Naturally Accelerates Over Time

OBJECTIVE

To investigate the cadence of recurrence in patients with low grade intermediate-risk non-muscle invasive bladder cancer (LG IR-NMIBC) based on clinical determinants. We aim to describe patterns in rates of recurrence to better inform surveillance regimens for this chronic, burdensome, and costly disease.

METHODS

Using baseline and follow-up data from participants in the West Midlands' (United Kingdom, UK) Bladder Cancer Prognosis Programme (BCPP), we assessed overall recurrence rate and recurrence-free intervals throughout the follow-up period for IR-NMIBC participants. Recurrence-free intervals were calculated using the Kaplan-Meier method.

RESULTS

We identified 379 patients with G1/G2 pTa tumors classified as intermediate risk. Median age was 70 and 284/379 (75%) were male. The median follow-up time was 4.2 years (95% CI: 3.9-4.8). After 5 years of follow-up, 53% of patients had at least one recurrence. One-year recurrence-free survival (RFS) was 75% and 4-year RFS was 50%. The median time to or between 1st, 2nd, 3rd, 4th, and 5th sequential recurrences was 49, 19, 12, 14, and 10 months, respectively.

CONCLUSION

Over half of patients with IR-NMIBC are destined to recur. Our data suggest that a subset of patients experience acceleration of recurrence over time and that this acceleration may serve as a potential kinetic biomarker for these individuals that could inform surveillance intervals and future treatment strategies.

The Association of Cerebral Oxygen Desaturation with Postoperative Cognitive Dysfunction in Older Patients: A Review

Postoperative cognitive dysfunction (POCD) is a neurological complication associated with surgery and anesthesia that is commonly observed in older patients, and it can significantly affect patient prognosis and survival. Therefore, predicting and preventing POCD is important. Regional cerebral oxygen saturation (rSO2) reflects cerebral perfusion and oxygenation, and decreased intraoperative cerebral oxygen saturation has been reported to increase the risk of POCD. In this review, we elucidated the important relationship between the decline in rSO2 and risk of POCD in older patients. We also emphasized the importance of monitoring rSO2 during surgery to predict and prevent adverse perioperative cognitive outcomes. The findings reveal that incorporating intraoperative rSO2 monitoring into clinical practice has potential benefits, such as protecting cognitive function, reducing perioperative adverse outcomes, and ultimately improving the overall quality of life of older adults.

Long-term cognitive outcomes after surgery and anesthesia: what we find depends on where we look

Purpose of review

To review how anecdote and narrative medicine, primary cohort studies, epidemiological studies, and the dementia literature can be bridged to understand long-term postoperative cognitive decline.

Recent findings

Primary cohort studies have measured recoverable declines in memory and executive function after major surgery, but less-appreciated sources also offer critical insights. Anecdote reveals that functionally-impactful cognitive decline may persist after physical recovery in some patients despite modern medications and monitoring, and that physicians are unprepared to address patients' cognitive concerns. However, epidemiological studies reproducibly demonstrate that elective surgery has no, or a negligible, average impact on cognition in older patients. Cognitively provocative factors - like medical hospital admissions or health factors like diabetes and smoking - are common in late life, and surgery likely contributes minimally to long-term cognitive change for most patients.

Summary

Patients should be reassured that, while anecdotes of durable cognitive change after surgery are easily accessible, most patients experience cognitive recovery after major surgery. However, those who do not recover deserve characterization of their symptoms and investigation of modifiable causes to facilitate cognitive recovery.

Quantifying the effect of shoulder size on operation duration: an analysis of stapes surgery outcomes

OBJECTIVE

To investigate the effect of body mass index on hearing outcomes, operative time and complication rates following stapes surgery.

METHOD

This is a five-year retrospective review of 402 charts from a single tertiary otology referral centre from 2015 to 2020.

RESULTS

When the patient's shoulder was adjacent to the surgeon's dominant hand, the average operative time of 40 minutes increased to 70 minutes because of a significant positive association between higher body mass index and longer operative times (normal body mass index group (<25 kg/m2) r = 0.273, p = 0.032; overweight body mass index group (25-30 kg/m2) r = 0.265, p = 0.019). Operative times were not significantly longer upon comparison of low and high body mass index groups without stratification by laterality (54.9 ± 19.6 minutes vs 57.8 ± 19.2 minutes, p = 0.127).

CONCLUSION

There is a clinically significant relationship between body mass index and operating times. This may be due to access limitations imposed by shoulder size.

The Postoperative Effects of Anesthesia Exposure on Cognitive Decline in Older Adults: A Narrative Review

BACKGROUND

As modern medicine continues to make strides in effective surgical treatments, we must also consider the critical impact of anesthesia on neuropsychological outcomes. Recent evidence suggests that anesthesia exposure may be a risk factor for postoperative cognitive decline and the eventual development of dementia.

OBJECTIVES

To explore the vulnerability of the aging brain in the context of anesthesia exposure in surgery, studies will be reviewed, and pertinent findings will be highlighted and explored to better understand risks and possible factors that need to be considered when contemplating surgery.

METHODS

A narrative review was conducted using a combination of MEDLINE and APA PsycINFO databases to shed light on themes across studies assessing general trends regarding the influence of anesthesia on postoperative cognitive decline.

RESULTS

A search of relevant literature identified 388 articles. Excluding results outside the parameters of this study, the review includes quality assessments for 24 articles.

CONCLUSION

While findings are inconclusive, suggestions for further investigation into the relationship between anesthesia exposure and increased risk for postoperative cognitive decline are discussed, in addition to factors that may allow for greater informed disclosure of potential risks of anesthesia in older adults.

Cognitive effects of carotid revascularization in octogenarians

BACKGROUND

Cognitive impairment is the epitome of cerebrovascular diseases, causing a significant economic burden on our health care system. Growing evidence has indicated the benefits of carotid interventions in patients with severe carotid atherosclerosis. However, the neurocognitive outcome of carotid revascularization in octogenarians is not clearly understood. We aim to evaluate postintervention cognitive changes in seniors older than 80 years.

METHODS

We prospectively recruited 170 patients undergoing carotid interventions. Neurocognitive testing was performed preoperatively and at 1, 6, and 12 months postoperatively. Episodic memory was assessed with Rey's Auditory Verbal Learning Test. Other executive functions and language measures were also evaluated at individual time points. Raw test scores were converted to z-scores or scaled scores adjusted for age and education. The sample was divided into 2 groups based on age: octogenarian (≥80 years) and nonoctogenarian (<80 years old). Postoperative cognitive scores were compared to baseline within each subcohort.

RESULTS

A total of 23 subjects (13%) were octogenarians, and 147 (87%) were younger than 80 years. Younger patients demonstrated significant cognitive improvements up to 12 months postop compared to the baseline. However, octogenarians exhibited a lack of improvement in verbal memory, measures of executive function, and language at all 3 postintervention time points.

CONCLUSION

Carotid interventions improve cognitive functions in younger patients with carotid occlusive atherosclerosis. However, no cognitive benefits were seen in male seniors older than 80 years. Further investigations are warranted to better understand the postinterventional cognitive changes in octogenarians.

Regional anesthesia in spine surgery: A narrative review

Background: Regional anesthesia, which refers to the use of anesthetics to provide analgesia to a specific body part or nervous innervation territory, has become increasingly popular in the field of spine surgery. With the application of these techniques, it has been postulated that patients will require less systemic analgesia, intraoperatively and postoperatively. The authors of this narrative review discuss the common regional anesthetic modalities applied to spine surgery, in addition to patient selection criteria, success in patients with multiple comorbid illnesses, and its adoption by surgeons. Materials and Methods: An advanced search was performed in the PubMed database to obtain Englishlanguage articles discussing regional anesthesia, awake spine surgery, and postoperative complications. Articles were screened for relevance, and 47 articles were incorporated into this narrative review. Results: Classic neuraxial and paraspinal techniques have allowed surgeons to perform posterior decompression, fusion, and revision procedures. Transversus abdominus plane and quadratus lumborum blocks have enabled better pain control in patients undergoing surgeries requiring anterior or lateral approaches. Documented benefits of regional anesthesia include shorter operative time, improved pain control and hemodynamic stability, as well as decreased cost and length of stay. Several case series have demonstrated the success of these techniques in highly comorbid patients. Conclusion: Regional anesthesia provides an exciting opportunity to make surgical treatment possible for spine patients with significant comorbidities. Although additional randomized controlled trials are necessary to further refine patient selection criteria, current data demonstrates its safety and efficacy in the operating room.

Assessing and managing frailty in emergency laparotomy: a WSES position paper

Many countries are facing an aging population. As people live longer, surgeons face the prospect of operating on increasingly older patients. Traditional teaching is that with older age, these patients face an increased risk of mortality and morbidity, even to a level deemed too prohibitive for surgery. However, this is not always true. An active 90-year-old patient can be much fitter than an overweight, sedentary 65-year-old patient with comorbidities. Recent literature shows that frailty-an age-related cumulative decline in multiple physiological systems, is therefore a better predictor of mortality and morbidity than chronological age alone. Despite recognition of frailty as an important tool in identifying vulnerable surgical patients, many surgeons still shun objective tools. The aim of this position paper was to perform a review of the existing literature and to provide recommendations on emergency laparotomy and in frail patients. This position paper was reviewed by an international expert panel composed of 37 experts who were asked to critically revise the manuscript and position statements. The position paper was conducted according to the WSES methodology. We shall present the derived statements upon which a consensus was reached, specifying the quality of the supporting evidence and suggesting future research directions.

Prospective analysis of plasma amyloid beta and postoperative delirium in the Interventions for Postoperative Delirium: Biomarker-3 study

BACKGROUND

The effect of postoperative delirium on the amyloid cascade of Alzheimer's dementia is poorly understood. Using early postoperative plasma biomarkers, we explored whether surgery and delirium are associated with changes in amyloid pathways.

METHODS

We analysed data from 100 participants in the Interventions for Postoperative Delirium: Biomarker-3 (IPOD-B3) cohort study in the USA (NCT03124303 and NCT01980511), which recruited participants aged >65 yr undergoing non-intracranial surgery. We assessed the relationship between the change in plasma amyloid beta ratio (AβR; Aβ42:Aβ40) and delirium incidence (defined by the 3-Minute Diagnostic Confusion Assessment Method) and severity (quantified by the Delirium Rating Scale-Revised-98, the study's primary outcome). We also tested the relationship between plasma amyloid beta and intraoperative variables.

RESULTS

Across all participants, the plasma AβR increased from the preoperative period to postoperative Day 1 (Wilcoxon P<0.001). However, this increase was not associated with delirium incidence (Wilcoxon P=0.22) or peak severity after adjusting for confounders (log[incidence rate ratio]=0.43; P=0.14). Postoperative Day 1 change in plasma AβR was not associated with postoperative Day 1 change in plasma tau, neurofilament light, or inflammatory markers (interleukin [IL]-1β, IL-1Ra, IL-2, IL-4, IL-6, IL-8, IL-10, and IL-12), or with operative time or low intraoperative arterial pressure.

CONCLUSIONS

Perioperative changes in plasma amyloid do not appear to be associated with postoperative delirium. Our findings do not support associations of dynamic changes in amyloid with postoperative delirium.

CLINICAL TRIAL REGISTRATION

.NCT03124303 and NCT01980511.

Effects of regional cerebral oxygen saturation monitoring on postoperative cognitive dysfunction in older patients: a systematic review and meta-analysis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is common after surgery and anesthesia, particularly in older patients. It has been reported that regional cerebral oxygen saturation (rSO₂) monitoring potentially influences the occurrence of POCD. However, its role in the prevention of POCD remains controversial in older patients. Additionally, the quality of evidence on this topic is still relatively poor.

METHODS

The electronic databases PubMed, EMBASE, Web of Science, and Cochrane Library were systematically searched using the indicated keywords from their inception to June 10, 2022. We limited our meta-analysis to randomized controlled trials (RCTs) that assessed the effects of rSO₂ monitoring on POCD in older patients. Methodological quality and risk of bias were assessed. The primary outcome was the incidence of POCD during hospitalization. The secondary outcomes were postoperative complications and the length of hospital stay (LOS). Odds ratios (OR) and 95% confidence intervals (CI) were calculated to determine the incidence of POCD and postoperative complications. The standardized mean difference (SMD) instead of the raw mean difference and 95% CI were calculated for LOS.

RESULTS

Six RCTs, involving 377 older patients, were included in this meta-analysis. The incidence of POCD ranges from 17 to 89%, with an overall prevalence of 47% in our pooled analysis. Our results demonstrated that rSO₂-guided intervention could reduce the incidence of POCD in older patients undergoing non-cardiac surgery (OR, 0.44; 95% CI, 0.25 to 0.79; P = 0.006) rather than cardiac surgery (OR, 0.69; 95% CI, 0.32 to 1.52; P = 0.36). Intraoperative rSO₂ monitoring was also associated with a significantly shorter LOS in older patients undergoing non-cardiac surgery (SMD, -0.93; 95% CI, -1.75 to -0.11; P = 0.03). Neither the incidence of postoperative cardiovascular (OR, 1.12; 95% CI, 0.40 to 3.17; P = 0.83) nor surgical (OR, 0.78; 95% CI, 0.35 to 1.75; P = 0.54) complications were affected by the use of rSO₂ monitoring.

CONCLUSION

The use of rSO₂ monitoring is associated with a lower risk of POCD and a shorter LOS in older patients undergoing non-cardiac surgery. This may have the potential to prevent POCD in high-risk populations. Further large RCTs are still warranted to support these preliminary findings.

Association of Indication for Hospitalization With Subsequent Amyloid Positron Emission Tomography and Magnetic Resonance Imaging Biomarkers

BACKGROUND

Hospitalization in older age is associated with accelerated cognitive decline, typically preceded by neuropathologic changes. We assess the association between indication for hospitalization and brain neurodegeneration.

METHODS

Included were participants from the Mayo Clinic Study of Aging, a population-based longitudinal study, with ≥1 brain imaging available in those older than 60 years of age between 2004 and 2017. Primary analyses used linear mixed-effects models to assess association of hospitalization with changes in longitudinal trajectory of cortical thinning, amyloid accumulation, and white matter hyperintensities (WMH). Additional analyses were performed with imaging outcomes dichotomized (normal vs abnormal) using Cox proportional hazards regression.

RESULTS

Of 2 480 participants, 1 966 had no hospitalization and 514 had ≥1 admission. Hospitalization was associated with accelerated cortical thinning (annual slope change -0.003 mm [95% confidence interval (CI) -0.005 to -0.001], p = .002), but not amyloid accumulation (0.003 [95% CI -0.001 to 0.006], p = .107), or WMH increase (0.011 cm3 [95% CI -0.001 to 0.023], p = .062). Interaction analyses assessing whether trajectory changes are dependent on admission type (medical vs surgical) found interactions for all outcomes. While surgical hospitalizations were not, medical hospitalizations were associated with accelerated cortical thinning (-0.004 mm [95% CI -0.008 to -0.001, p = .014); amyloid accumulation (0.010, [95% CI 0.002 to 0.017, p = .011), and WMH increase (0.035 cm3 [95% CI 0.012 to 0.058, p = .006). Hospitalization was not associated with developing abnormal cortical thinning (p = .407), amyloid accumulation (p = .596), or WMH/infarctions score (p = .565).

CONCLUSIONS

Medical hospitalizations were associated with accelerated cortical thinning, amyloid accumulation, and WMH increases. These changes were modest and did not translate to increased risk for crossing the abnormality threshold.

Review of Neurofilaments as Biomarkers in Sepsis-Associated Encephalopathy

Sepsis is a common and fatal disease, especially in critically ill patients. Sepsis-associated encephalopathy (SAE) is a diffuse brain dysfunction with acute altered consciousness, permanent cognitive impairment, and even coma, accompanied by sepsis, without direct central nervous system infection. When managing SAE, early identification and quantification of axonal damage facilitate faster and more accurate diagnosis and prognosis. Although no specific markers for SAE have been identified, several biomarkers have been proposed. Neurofilament light chain (NFL) is a highly expressed cytoskeletal component of neurofilament (NF) proteins that can be found in blood and cerebrospinal fluid (CSF) after exposure to axonal injury. NFs can be used as diagnostic and prognostic biomarkers for sepsis-related brain injury. Phosphorylation of NFs contributes to the maturation and stabilization of cytoskeletal structures, especially axons, and facilitates axonal transport, including mitochondrial transport and energy transport. The stability of NF proteins can be assessed by monitoring the expression of NF genes. Furthermore, phosphorylation levels of NFs can be monitored to determine mitochondrial axonal transport associated with cellular energy metabolism at distal axons to assess progression during SAE treatment. This paper provides new insights into the biological characteristics, detection techniques, and scientific achievements of NFs, and discusses the underlying mechanisms and future research directions of NFs in SAE.

Hydrogen Gas Treatment Improves Postoperative Delirium and Cognitive Dysfunction in Elderly Noncardiac Patients

Purpose: Postoperative delirium is a state of acute brain dysfunction characterized by fluctuating mental status that affects millions of patients each year. We used prophylactic inhalation of hydrogen gas in elderly patients undergoing elective surgery to compare their occurrence of postoperative delirium with that of controls. Methods: A total of 184 patients aged ≥ 65 years were enrolled and randomized into either a control group or a hydrogen inhalation group. The quality of sleep was assessed 1 day before and 1, 3, and 7 days after surgery at 8 A.M. The Confusion Assessment Method (CAM) was used as a screening tool for delirium and assessed the patients’ state of consciousness 1−7 days after surgery. Results: Postoperative delirium occurred in 17 (24%) of 70 patients without hydrogen inhalation and in 10 (12%) of 83 patients after hydrogen inhalation. The incidence of delirium was decreased in the hydrogen group. No significant differences were found between length of stay in hospital after surgery and sleep quality at 1, 3, and 7 days postoperatively between the two groups. The numerical rating scale (NRS) pain scores were higher in the hydrogen group (4.08 ± 1.77) than the control group (3.54 ± 1.77) on day 1 (p < 0.05); however, the mean difference between the two groups was small (1 to 1.6). There were no significant differences on day 3 and 7. The postoperative C-reactive protein level was significantly lower in the hydrogen group than the control group. Conclusions: This study suggests that hydrogen inhalation can prevent postoperative delirium in elderly noncardiac patients by reducing the inflammatory response.

Clinical Effect of Application of Interventional Treatment Models for Improvement of Quality of Postoperative Recovery in Elderly Patients with Total Hip Arthroplasty

OBJECTIVE

To investigate the application value of the interventional treatment model for improving the recovery of elderly patients after total hip arthroplasty (THA).

METHODS

A total of 50 patients who received THA were randomly divided into the control group (25 cases) undergoing traditional treatment and the experimental group (25 cases) undergoing intervention of cognition, emotion, environment, education, nutrition, and sleep. The mini-mental state examination (MMSE) score, the incidence and duration of postoperative cognitive dysfunction (POCD), the out-of-bed activity time, hospital stays, and the satisfaction degree of patients were compared between the two groups.

RESULTS

There was no statistically significant difference in basic information between the two groups. On days 7 and 14 after surgery, the MMSE score of the control group was significantly lower than that of the experimental group (P <0.05). The incidence of POCD in the experimental group was lower and its duration was shorter than in the control group but without statistical significance. Besides, the significantly decreased out-of-bed activity time, the reduced length of hospital stay, and the higher satisfaction degree were observed in the experimental group (P <0.05).

CONCLUSION

Interventional treatment model could significantly increase the MMSE score, accelerate the recovery of elderly patients after THA, and increase their satisfaction degree.

Long-term Cognitive Trajectory After Total Joint Arthroplasty

Importance

Individuals with total joint arthroplasty (TJA) have long-term exposure to metal-containing implants; however, whether long-term exposure to artificial implants is associated with cognitive function is unknown.

Objective

To compare long-term cognitive trajectories in individuals with and without TJA.

Design, Setting, and Participants

This population-based cohort study assessed serial cognitive evaluations of 5550 participants (≥50 years of age) from the Mayo Clinic Study of Aging between November 1, 2004, and December 31, 2020.

Exposures

Total joint arthroplasty of the hip or the knee.

Main Outcomes and Measures

Linear mixed-effects models were used to compare the annualized rate of change in global and domain-specific cognitive scores in participants with and without TJA, adjusting for age, sex, educational level, apolipoprotein E ε4 carrier status, and cognitive test practice effects.

Results

A total of 5550 participants (mean [SD] age at baseline, 73.04 [10.02] years; 2830 [51.0%] male) were evaluated. A total of 952 participants had undergone at least 1 TJA of the hip (THA, n = 430) or the knee (TKA, n = 626) before or after entry into the cohort. Participants with TJA were older, more likely to be female, and had a higher body mass index than participants without TJA. No difference was observed in the rate of cognitive decline in participants with and without TJA until 80 years of age. A slightly faster cognitive decline at 80 years or older and more than 8 years from surgery was observed (b = -0.03; 95% CI, -0.04 to -0.02). In stratified analyses by surgery type, the faster decline was observed primarily among older participants with TKA (b = -0.04; 95% CI, -0.06 to -0.02).

Conclusions and Relevance

In this cohort study, long-term cognitive trajectories in individuals with and without TJA were largely similar except for a slightly faster decline among the oldest patients with TKA; however, the magnitude of difference was small and of unknown clinical significance.

Alzheimer's Dementia After Exposure to Anesthesia and Surgery in the Elderly: A Matched Natural Experiment Using Appendicitis

OBJECTIVE

The aim of this study was to determine whether surgery and anesthesia in the elderly may promote Alzheimer disease and related dementias (ADRD).

BACKGROUND

There is a substantial conflicting literature concerning the hypothesis that surgery and anesthesia promotes ADRD. Much of the literature is confounded by indications for surgery or has small sample size. This study examines elderly patients with appendicitis, a common condition that strikes mostly at random after controlling for some known associations.

METHODS

A matched natural experiment of patients undergoing appendectomy for appendicitis versus control patients without appendicitis using Medicare data from 2002 to 2017, examining 54,996 patients without previous diagnoses of ADRD, cognitive impairment, or neurological degeneration, who developed appendicitis between ages 68 through 77 years and underwent an appendectomy (the ''Appendectomy'' treated group), matching them 5:1 to 274,980 controls, examining the subsequent hazard for developing ADRD.

RESULTS

The hazard ratio (HR) for developing ADRD or death was lower in the Appendectomy group than controls: HR = 0.96 [95% confidence interval (CI) 0.94-0.98], P < 0.0001, (28.2% in Appendectomy vs 29.1% in controls, at 7.5 years). The HR for death was 0.97 (95% CI 0.95-0.99), P = 0.002, (22.7% vs 23.1% at 7.5 years). The HR for developing ADRD alone was 0.89 (95% CI 0.86-0.92), P < 0.0001, (7.6% in Appendectomy vs 8.6% in controls, at 7.5 years). No subgroup analyses found significantly elevated rates of ADRD in the Appendectomy group.

CONCLUSION

In this natural experiment involving 329,976 elderly patients, exposure to appendectomy surgery and anesthesia did not increase the subsequent rate of ADRD.

Anesthesia promotes acute expression of genes related to Alzheimer's disease and latent tau aggregation in transgenic mouse models of tauopathy

Background

Exposure to anesthesia in the elderly might increase the risk of dementia. Although the mechanism underlying the association is uncertain, anesthesia has been shown to induce acute tau hyperphosphorylation in preclinical models. We sought to investigate the impact of anesthesia on gene expression and on acute and long-term changes in tau biochemistry in transgenic models of tauopathy in order to better understand how anesthesia influences the pathophysiology of dementia.

Methods

We exposed mice with over-expressed human mutant tau (P301L and hyperdopaminergic COMTKO/P301L) to two hours of isoflurane and compared anesthetized mice to controls at several time points. We evaluated tau hyperphosphorylation with quantitative high-sensitivity enzyme-linked immunosorbent assay and performed differential expression and functional transcriptome analyses following bulk mRNA-sequencing.

Results

Anesthesia induced acute hyperphosphorylation of tau at epitopes related to Alzheimer’s disease (AD) in both P301L-based models. Anesthesia was associated with differential expression of genes in the neurodegenerative pathways (e.g., AD-risk genes ApoE and Trem2) and thermogenesis pathway, which is related to both mammalian hibernation and tau phosphorylation. One and three months after anesthesia, hyperphosphorylated tau aggregates were increased in the anesthetized mice.

Conclusions

Anesthesia may influence the expression of AD-risk genes and induce biochemical changes in tau that promote aggregation even after single exposure. Further preclinical and human studies are necessary to establish the relevance of our transcriptomic and biochemical findings in these preclinical models to the pathogenesis of dementia following anesthesia.

Trial registration: Not applicable.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-022-00506-4.

Association of blood pressure variability with short- and long-term cognitive outcomes in patients with critical illness

BACKGROUND

Blood pressure variability (BPV), a modifiable risk factor, can compromise cerebral perfusion in critically ill patients. We studied the association between BPV in the intensive care unit (ICU) and short- and long-term cognitive outcomes.

METHODS

All patients were ≥50 years old. The short-term cognitive end points were delirium and depressed alertness without delirium. The long-term outcome was change in the slope of longitudinal cognitive scores. Primary BPV measure was average real variability (ARV) of systolic blood pressure. Associations were assessed with multivariable multinominal logistic regression and linear mixed effects models.

RESULTS

Of 794 patients (1130 admissions) 185 developed delirium and 274 developed depressed alertness. There was a dose-response association of 24-h systolic ARV with delirium (adjusted OR, 95% CI 2.15 per 5 mm Hg increase, 1.31-3.06, P < 0.017) and with depressed alertness (OR 1.89, 95% CI 1.18-3.03, P < 0.008). For 371 patients with available longitudinal cognitive scores, the decline in cognitive trajectory was accelerated after discharge (annual change OR -0.097, 95% CI -0.122 to -0.073). This acceleration increased with delirium (additional decline -0.132 [-0.233 to 0.030], P = 0.011). We found no significant association between BPV and post-ICU cognitive trajectory.

CONCLUSIONS

BPV was associated with increased likelihood of delirium in the ICU. Delirium, but not BPV, was associated with long-term cognitive decline.

Surgical Hospitalization Is Not Associated With Cognitive Trajectory Over 6 Years in Healthy Older Australians

OBJECTIVE

The aim was to investigate the association of cognitive trajectories and overnight surgical hospitalization in older adults, while controlling for and comparing with the association with acute medical hospitalizations.

DESIGN

This is a secondary analysis of data from a population-based, longitudinal cohort study of older Australians.

SETTING AND PARTICIPANTS

Cognition was assessed with 4 biennial waves of prospective neuropsychological data from 1026 Sydney Memory and Aging Study participants age 70 to 90 years at baseline. Hospitalization exposure was obtained from 10 years of electronically linked data from the New South Wales Admitted Patient Data Collection.

METHODS

Latent growth curve modeling estimated global cognition z score baseline and slope over 6 years, and the effects of contemporaneous surgical and medical hospitalization predictors while controlling for potential demographic and comorbidity confounders.

RESULTS

After controlling for confounding variables, this analysis showed that overnight surgical hospitalizations were not associated with worse baseline global cognition or accelerated cognitive decline over 6 years. This was despite this cohort having more surgeries and more complex surgeries compared with Australian data for overnight hospitalizations in over 70-year-olds. Conversely, recent medical hospitalizations were associated with accelerated cognitive decline.

CONCLUSIONS AND IMPLICATIONS

This analysis finds that surgery and anesthesia are unlikely to be risk factors for medium to long-term global cognitive decline in healthy older adults, while controlling for contemporaneous medical hospitalizations. These findings are contrary to prior conclusions from several surgical studies that may have been impeded by insufficient comparison groups. They are, however, consistent with recent population-based studies suggesting surgery has minimal association with cognitive decline in the medium to long-term. Future research needs to clarify the association of surgical hospitalization with the full spectrum of cognitive outcomes including subjective cognitive complaints and dementia, and importantly, how these cognitive outcomes correlate with clinically significant functional changes.

Potential Neuroprotective Role of Sugammadex: A Clinical Study on Cognitive Function Assessment in an Enhanced Recovery After Cardiac Surgery Approach and an Experimental Study

Background

Postoperative cognitive dysfunction affects the quality of recovery, particularly affecting the elderly, and poses a burden on the health system. We hypothesize that the use of sugammadex (SG) could optimize the quality of postoperative cognitive function and overall recovery through a neuroprotective effect.

Methods

A pilot observational study on patients undergoing cardiac surgery with enhanced recovery after cardiac surgery (ERACS) approach, was designed to compare SG-treated (n = 14) vs. neostigmine (NG)-treated (n = 7) patients. The Postoperative Quality Recovery Scale (PQRS) was used at different times to evaluate cognitive function and overall recovery of the patients. An online survey among anesthesiologists on SG use was also performed. Additionally, an animal model study was designed to explore the effects of SG on the hippocampus.

Results

Sugammadex (SG) was associated with favorable postoperative recovery in cognitive domains particularly 30 days after surgery in patients undergoing aortic valve replacement by cardiopulmonary bypass and the ERACS approach; however, it failed to demonstrate a short-term decrease in length of intensive care unit (ICU) and hospital stay. The survey information indicated a positive appreciation of SG recovery properties. SG reverts postoperative memory deficit and induces the expression of anti-inflammatory microglial markers.

Conclusion

The results show a postoperative cognitive improvement by SG treatment in patients undergoing aortic valve replacement procedure by the ERACS approach. Additionally, experimental data from an animal model of mild surgery confirm the cognitive effect of SG and suggest a potential effect over glia cells as an underlying mechanism.

Does Preoperative Cognitive Optimization Improve Postoperative Outcomes in the Elderly?

Perioperative neurocognitive disorder (PND) is a growing concern, affecting several million elderly patients each year in the United States, but strategies for its effective prevention have not yet been established. Humeidan et al. recently demonstrated that preoperative brain exercise resulted in a decrease in postoperative delirium incidence in elderly surgical patients, suggesting the potential of presurgical cognitive optimization to improve postoperative cognitive outcomes. This brief review summarizes the current knowledge regarding preoperative cognitive optimization and highlights landmark studies, as well as current ongoing studies, as the field is rapidly growing. This review further discusses the benefit of cognitive training in non-surgical elderly populations and the role of cognitive training in patients with preexisting cognitive impairment or dementia. The review also examines preclinical evidence in support of cognitive training, which can facilitate understanding of brain plasticity and the pathophysiology of PND. The literature suggests positive impacts of presurgical cognitive optimization, but further studies are encouraged to establish effective cognitive training programs for elderly presurgical patients.

Enriched Environment Prevents Surgery-Induced Persistent Neural Inhibition and Cognitive Dysfunction

Perioperative neurocognitive disorders (PND) encompass short-term delirium and long-term cognitive dysfunction. Aging increases the susceptibility to PND, yet the neural mechanism is not known. In this study, we monitored the dynamic changes of neuronal activity in the prelimbic cortex before and after surgery. We found that anesthesia combined with surgery, but not anesthesia alone, induced a prolonged decrease in neuronal activity during the post-operation period in the aged mice, but not in the adult mice. The prolonged decrease in neuronal activity was accompanied by surgery-induced microglial activation and proinflammatory cytokines expression. Importantly, we found that the enriched environment (EE) completely prevented both the prolonged neural inhibition and neuroinflammation, and improved cognitive function in the aged mice. These results indicate that the prolonged neural inhibition correlated to PND and that EE before the surgery could effectively alleviate the surgery- induced cognitive dysfunction.

Immune markers are associated with cognitive performance in a multiethnic cohort: The Northern Manhattan Study

OBJECTIVE

To determine whether immune protein panels add significant information to correlates of cognition.

BACKGROUND

Immune mechanisms in vascular cognitive aging are incompletely characterized.

DESIGN/METHODS

A subsample of the prospective Northern Manhattan Study underwent detailed neuropsychological testing. Cognitive scores were converted into Z-scores and categorized into four domains (memory, language, processing speed, and executive function) based on factor analysis. Blood samples were analyzed using a 60-plex immunoassay. We used least absolute shrinkage and selection operator (LASSO) procedures to select markers and their interactions independently associated with cognitive scores. Linear regression models assessed cross-sectional associations of known correlates of cognition with cognitive scores, and assessed model fit before and after addition of LASSO-selected immune markers.

RESULTS

Among 1179 participants (mean age 70 ± 8.9 years, 60% women, 68% Hispanic), inclusion of LASSO-selected immune markers improved model fit above age, education, and other risk factors (p for likelihood ratio test < 0.005 for all domains). C-C Motif Chemokine Ligand 11 (CCL 11, eotaxin), C-X-C Motif Chemokine Ligand 9 (CXCL9), hepatocyte growth factor (HGF), and serpin E1 (plasminogen activator inhibitor-1) were associated with each of the domains and with overall cognitive function. Immune marker effects were comparable to conventional risk factors: for executive function, each standard deviation (SD) increase in CCL11 was associated with an effect equivalent to aging three years; for memory, HGF had twice the effect of aging.

CONCLUSIONS

Immune markers associate with cognitive function in a multi-ethnic cohort. Further work is needed to validate these findings and determine optimal treatment targets.

Cochlear implantation under local anesthesia in 117 cases: patients' subjective experience and outcomes

Purpose

To report the outcomes and the patients’ subjective experience of cochlear implantation (CI) performed under local anesthesia (LA). To describe a new form of intraoperative cochlear monitoring based on the patients subjective sound perception during CI.

Methods

In this retrospective case–cohort study, 117 patients underwent CI under LA with (n = 58) or without conscious sedation (n = 59). Included were primarily elderly patients with elevated risks for general anesthesia and recently patients with residual hearing eligible for electro-acoustic stimulation (EAS) (n = 27), in whom hearing could be monitored during the electrode insertion. A 500 Hz test tone was presented and the patient reported  of subjective changes in loudness, leading to a modification of the insertion. A questionnaire was sent to all patients in which they assessed their subjective experience.

Results

All patients were successfully operated under LA without the need to intraoperatively convert to general anesthesia. 90% of the patients reported that the surgery was a positive experience. The vast majority, 90% of patients were satisfied with the overall treatment and with intraoperative pain management and 84% of the patients would opt for local anesthesia again. Cochlear monitoring by the patients’ subjective sound perception enabled for atraumatic insertions as all EAS patients could hear the test tone up to the end of the surgery.

Conclusions

CI under LA was well tolerated and recommended by the vast majority of patients. In addition, it offers the possibility to monitor the patients’ hearing during the electrode insertion, which may help to prevent insertion trauma.

Emerging Role of Long Noncoding RNAs in Perioperative Neurocognitive Disorders and Anesthetic-Induced Developmental Neurotoxicity

Preclinical investigations in animal models have consistently demonstrated neurobiological changes and life-long cognitive deficits following exposure to widely used anesthetics early in life. However, the mechanisms by which these exposures affect brain function remain poorly understood, therefore, limiting the efficacy of current diagnostic and therapeutic options in human studies. The human brain exhibits an abundant expression of long noncoding RNAs (lncRNAs). These biologically active transcripts play critical roles in a diverse array of functions, including epigenetic regulation. Changes in lncRNA expression have been linked with brain development, normal CNS processes, brain injuries, and the development of neurodegenerative diseases, and many lncRNAs are known to have brain-specific expression. Aberrant lncRNA expression has also been implicated in areas of growing importance in anesthesia-related research, including anesthetic-induced developmental neurotoxicity (AIDN), a condition defined by neurological changes occurring in patients repeatedly exposed to anesthesia, and the related condition of perioperative neurocognitive disorder (PND). In this review, we detail recent advances in PND and AIDN research and summarize the evidence supporting roles for lncRNAs in the brain under both normal and pathologic conditions. We also discuss lncRNAs that have been linked with PND and AIDN, and conclude with a discussion of the clinical potential for lncRNAs to serve as diagnostic and therapeutic targets for the prevention of these neurocognitive disorders and the challenges facing the identification and characterization of associated lncRNAs.

Cerebral Hypoxia: Its Role in Age-Related Chronic and Acute Cognitive Dysfunction

Postoperative cognitive dysfunction (POCD) has been reported with widely varying frequency but appears to be strongly associated with aging. Outside of the surgical arena, chronic and acute cerebral hypoxia may exist as a result of respiratory, cardiovascular, or anemic conditions. Hypoxia has been extensively implicated in cognitive impairment. Furthermore, disease states associated with hypoxia both accompany and progress with aging. Perioperative cerebral hypoxia is likely underdiagnosed, and its contribution to POCD is underappreciated. Herein, we discuss the various disease processes and forms in which hypoxia may contribute to POCD. Furthermore, we outline hypoxia-related mechanisms, such as hypoxia-inducible factor activation, cerebral ischemia, cerebrovascular reserve, excitotoxicity, and neuroinflammation, which may contribute to cognitive impairment and how these mechanisms interact with aging. Finally, we discuss opportunities to prevent and manage POCD related to hypoxia.

Association of Hospitalization with Long-Term Cognitive Trajectories in Older Adults

IMPORTANCE

Hospitalizations are associated with cognitive decline in older adults.

OBJECTIVE

To determine the association between hospitalization characteristics and the trajectory of cognitive function in older adults.

DESIGN

Population-based longitudinal study of cognitive aging.

SETTING

Olmsted Medical Center and Mayo Clinic, the only centers in Olmsted County, Minnesota, with hospitalization capacity.

PARTICIPANTS

Individuals without dementia at baseline, with consecutive cognitive assessments from 2004 through 2017, and at least one visit after the age of 60.

MEASUREMENTS

The primary outcome was longitudinal changes in global cognitive z-score. Secondary outcomes were changes in four cognitive domains: memory, attention/executive function, language, and visuospatial skills. Hospitalization characteristics analyzed included elective versus nonelective, medical versus surgical, critical care versus no critical care admission, and long versus short duration admissions.

RESULTS

Of 4,587 participants, 1,622 had 1 and more hospital admission. Before hospitalization, the average slope of the global z-score was -0.031 units/year. After hospitalization, the rate of annual global z-score accelerated by -0.051 (95% CI = -0.057, -0.045) units, P < .001, resulting in an estimated annual slope after the first hospitalization of -0.082. The accelerated decline was found in all four cognitive domains (memory, visuospatial, language, and executive, all P < .001). The acceleration of the decline in global z-score following hospitalization was greater for medical compared to surgical hospitalizations (slope change following hospitalization = -0.064 vs -0.034 for medical vs surgical, P < .001), and nonelective compared to elective admissions (slope change following hospitalization = -0.075 vs -0.037 for nonelective vs elective, P < .001). The acceleration of cognitive decline was not different for hospitalization with intensive care unit admission versus not.

CONCLUSIONS

Hospitalization of older adults is associated with accelerated decline of global and domain-specific cognitive domains, with the rate of decline dependent upon type of admission. The clinical impact of this accelerated decline will depend on the individual's baseline cognitive reserve and expected longevity.

Brain MRI after critical care admission: A longitudinal imaging study

PURPOSE

To investigate the association between episodes of critical care hospitalizations and delirium with structural brain changes in older adults.

MATERIALS AND METHODS

We included Mayo Clinic Study of Aging participants ≥60 years old at the time of study enrollment (October 29, 2004, through September 11, 2017) with available brain MRI and 'amyloid' positron emission tomography (PET) scans. We tested the hypothesis that a) intensive care unit (ICU) admission is associated with greater cortical thinning and atrophy in entorhinal cortex, inferior temporal cortex, middle temporal cortex, and fusiform cortex (Alzheimer''s disease-signature regions); b) atrophy in hippocampus and corpus callosum; c) delirium accelerates these changes; and d) ICU admission is not associated with increased deposition of cortical amyloid.

RESULTS

ICU admission was associated with cortical thinning in temporal, frontal, and parietal cortices, and decreases in hippocampal/corpus callosum volumes, but not Alzheimer''s disease-signature regions. For hippocampal volume, and 10 of 14 cortical thickness measurements, the change following ICU admission was significantly more pronounced for those who experienced delirium. ICU admission was not associated with an increased amyloid burden.

CONCLUSIONS

Critical care hospitalization is associated with accelerated brain atrophy in selected brain regions, without increases in amyloid deposition, suggesting a pathogenesis based on neurodegeneration unrelated to Alzheimer''s pathway.

The Chemical Exposome of Human Aging

Aging is an inevitable biological phenomenon displayed by single cells and organs to entire organismal systems. Aging as a biological process is characterized as a progressive decline in intrinsic biological function. Understanding the causative mechanisms of aging has always captured the imagination of researchers since time immemorial. Although both biological and chronological aging are well defined and studied in terms of genetic, epigenetic, and lifestyle predispositions, the hallmarks of aging in terms of small molecules (i.e., endogenous metabolites to chemical exposures) are limited to obscure. On top of the endogenous metabolites leading to the onset and progression of healthy aging, human beings are constantly exposed to a natural and anthropogenic "chemical" environment round the clock, from conception till death, affecting one's physiology, health and well-being, and disease predisposition. The research community has started gaining sizeable insights into deciphering the aging factors such as immunosenescence, nutrition, frailty, inflamm-aging, and diseases till date, without much input from their interaction with exogenous chemical exposures. The "exposome" around us, mostly, accelerates the process of aging by affecting the internal biological pathways and signaling mechanisms that result in the deterioration of human health. However, the entirety of exposome on human aging is far from established. This review intends to catalog the known and established associations of the exposome from past studies focusing on aging in humans and other model organisms. Further discussed are the current technologies and informatics tools that enable the study of aging exposotypes, and thus, provide a window of opportunities and challenges to study the "aging exposome" in granular details.

Association between plasma tau and postoperative delirium incidence and severity: a prospective observational study

BACKGROUND

Postoperative delirium is associated with increases in the neuronal injury biomarker, neurofilament light (NfL). Here we tested whether two other biomarkers, glial fibrillary acidic protein (GFAP) and tau, are associated with postoperative delirium.

METHODS

A total of 114 surgical patients were recruited into two prospective biomarker cohort studies with assessment of delirium severity and incidence. Plasma samples were sent for biomarker analysis including tau, NfL, and GFAP, and a panel of 10 cytokines. We determined a priori to adjust for interleukin-8 (IL-8), a marker of inflammation, when assessing associations between biomarkers and delirium incidence and severity.

RESULTS

GFAP concentrations showed no relationship to delirium. The change in tau from preoperative concentrations to postoperative Day 1 was greater in patients with postoperative delirium (P<0.001) and correlated with delirium severity (ρ=0.39, P<0.001). The change in tau correlated with increases in IL-8 (P<0.001) and IL-10 (P=0.0029). Linear regression showed that the relevant clinical predictors of tau changes were age (P=0.037), prior stroke/transient ischaemic attack (P=0.001), and surgical blood loss (P<0.001). After adjusting for age, sex, preoperative cognition, and change in IL-8, tau remained significantly associated with delirium severity (P=0.026). Using linear mixed effect models, only tau (not NfL or IL-8) predicted recovery from delirium (P<0.001).

CONCLUSIONS

The change in plasma tau was associated with delirium incidence and severity, and resolved over time in parallel with delirium features. The impact of this putative perioperative neuronal injury biomarker on long-term cognition merits further investigation.

CLINICAL TRIAL REGISTRATION

NCT02926417 and NCT03124303.

DNA Methylation Manipulation of Memory Genes Is Involved in Sevoflurane Induced Cognitive Impairments in Aged Rats

DNA methylation is an essential epigenetic mechanism involving in gene transcription modulation. An age-related increase in promoter methylation has been observed for neuronal activity and memory genes, and participates in neurological disorders. However, the position and precise mechanism of DNA methylation for memory gene modulation in anesthesia related cognitive impairment remained to be determined. Here, we studied the effects of sevoflurane anesthesia on the transcription of memory genes in the aged rat hippocampus. Then, we investigated changes in DNA methylation of involved genes and verified whether dysregulated DNA methylation would contribute to anesthesia induced cognitive impairment. The results indicated that sevoflurane anesthesia down-regulated the mRNA and protein levels of three memory genes, Arc, Bdnf, and Reln, which were accompanied with promoter hypermethylation and increased Dnmt1, Dnmt3a, and Mecp2 expression, and finally impaired hippocampus dependent memory. Furthermore, inhibition of DNA hypermethylation by 5-Aza rescued sevoflurane induced memory gene expression decrease and cognitive impairment. These findings provide an epigenetic understanding for the pathophysiology of cognitive impairment induced by general anesthesia in aged brain.

Association between surgery with anesthesia and cognitive decline in older adults: Analysis using shared parameter models for informative dropout

Objectives/Goals:

The association between surgery with general anesthesia (exposure) and cognition (outcome) among older adults has been studied with mixed conclusions. We revisited a recent analysis to provide missing data education and discuss implications of biostatistical methodology for informative dropout following dementia diagnosis.

Methods/study population:

We used data from the Mayo Clinic Study of Aging, a longitudinal study of prevalence, incidence, and risk factors for mild cognitive impairment (MCI) and dementia. We fit linear mixed effects models (LMMs) to assess the association between anesthesia exposure and subsequent trajectories of cognitive z-scores assuming data missing at random, hypothesizing that exposure is associated with greater decline in cognitive function. Additionally, we used shared parameter models for informative dropout assuming data missing not at random.

Results:

A total of 1948 non-demented participants were included. Median age was 79 years, 49% were female, and 16% had MCI at enrollment. Among median follow-up of 4 study visits over 6.6 years, 172 subjects developed dementia, 270 died, and 594 participants underwent anesthesia. In LMMs, exposure to anesthesia was associated with decline in cognitive function over time (change in annual cognitive z-score slope = −0.063, 95% CI: (−0.080, −0.046), p < 0.001). Accounting for informative dropout using shared parameter models, exposure was associated with greater cognitive decline (change in annual slope = −0.081, 95% CI: (−0.137, −0.026), p = 0.004).

Discussion:

We revisited prior work by our group with a focus on informative dropout. Although the conclusions are similar, we demonstrated the potential impact of novel biostatistics methodology in longitudinal clinical research.

Anesthesia With and Without Nitrous Oxide and Long-term Cognitive Trajectories in Older Adults

BACKGROUND

We evaluated the hypothesis that the rate of postoperative decline in global cognition is greater in older adults exposed to general anesthesia with nitrous oxide (N2O) compared to general anesthesia without N2O.

METHODS

Longitudinal measures of cognitive function were analyzed in nondemented adults, 70-91 years of age, enrolled in the Mayo Clinic Study of Aging. Linear mixed-effects models with time-varying covariates assessed the relationship between exposure to surgery with general anesthesia (surgery/GA) with or without N2O and the rate of long-term cognitive changes. Global cognition and domain-specific cognitive outcomes were defined using z scores, which measure how far an observation is, in standard deviations, from the unimpaired population mean.

RESULTS

The analysis included 1819 participants: 280 exposed to GA without N2O following enrollment and before censoring during follow-up (median [interquartile range {IQR}] follow-up of 5.4 [3.9-7.9] years); 256 exposed to GA with N2O (follow-up 5.6 [4.0-7.9] years); and 1283 not exposed to surgery/GA (follow-up 4.1 [2.5-6.4] years). The slope of the global cognitive z score was significantly more negative following exposure to surgery/GA after enrollment (change in slope of -0.062 [95% confidence interval {CI}, -0.085 to -0.039] for GA without N2O, and -0.058 [95% CI, -0.080 to -0.035] for GA with N2O, both P < .001). The change in slope following exposure to surgery/GA did not differ between those exposed to anesthesia without versus with N2O (estimated difference -0.004 [95% CI, -0.035 to 0.026], P = .783).

CONCLUSIONS

Exposure to surgery/GA is associated with a small, but statistically significant decline in cognitive z scores. Cognitive decline did not differ between anesthetics with and without N2O. This finding provides evidence that the use of N2O in older adults does not need to be avoided because of concerns related to decline in cognition.

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.

Association Between Critical Care Admissions and Cognitive Trajectories in Older Adults

OBJECTIVES

Patients requiring admission to an ICU may subsequently experience cognitive decline. Our objective was to investigate longitudinal cognitive trajectories in older adults hospitalized in ICUs. We hypothesized that individuals hospitalized for critical illness develop greater cognitive decline compared with those who do not require ICU admission.

DESIGN

A retrospective cohort study using prospectively collected cognitive scores of participants enrolled in the Mayo Clinic Study of Aging and ICU admissions retrospectively ascertained from electronic medical records. A covariate-adjusted linear mixed effects model with random intercepts and slopes assessed the relationship between ICU admissions and the slope of global cognitive z scores and domains scores (memory, attention/executive, visuospatial, and language).

SETTING

ICU admissions and cognitive scores in the Mayo Clinic Study of Aging from October 1, 2004, to September 11, 2017.

PATIENTS

Nondemented participants age 50 through 91 at enrollment in the Mayo Clinic Study of Aging with an initial cognitive assessment and at least one follow-up visit.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 3,673 participants, 372 had at least one ICU admission with median (25-75th percentile) follow-up after first ICU admission of 2.5 years (1.2-4.4 yr). For global cognitive z score, admission to an ICU was associated with greater decline in scores over time compared with participants not requiring ICU admission (difference in annual slope = -0.028; 95% CI, -0.044 to -0.012; p < 0.001). ICU admission was associated with greater declines in memory (-0.029; 95% CI, -0.047 to -0.011; p = 0.002), attention/executive (-0.020; 95% CI, -0.037 to -0.004; p = 0.016), and visuospatial (-0.013; 95% CI, -0.026 to -0.001; p = 0.041) domains. ICU admissions with delirium were associated with greater declines in memory (interaction p = 0.006) and language (interaction p = 0.002) domains than ICU admissions without delirium.

CONCLUSIONS

In older adults, ICU admission was associated with greater long-term cognitive decline compared with patients without ICU admission. These findings were more pronounced in those who develop delirium while in the ICU.

Preoperative cognitive impairment associated with oversedation during recovery from anesthesia

PURPOSE

Our objective was to examine the association between preoperative cognitive status and postoperative recovery from anesthesia.

METHODS

We included patients (70-91 years old) from the Mayo Clinic Study of Aging who received general anesthesia and were admitted to the postanesthesia care unit from January 1, 2010 through April 30, 2018. Procedures were categorized according to patient's preoperative cognitive status: cognitive impaired (CI) and cognitive unimpaired (CU). Perioperative records were reviewed and analyses were performed with generalized estimating equations.

RESULTS

A total of 896 procedures from 611 patients were included, with 203 (22.7%) procedures in the CI group. Compared to CU procedures, CI procedures had higher rates of moderate-deep sedation during anesthesia recovery (52 [25.6%] vs. 103 [14.9%]; odds ratio [OR], 1.91; 95% CI, 1.30-2.80; P  < 0.01), postoperative pulmonary complications (22 [10.8%] vs. 34 [4.9%]; OR, 2.36[1.22-4.54]; P  =  0.01), and postoperative delirium (32 [16.2%] vs. 24 [3.5%]; OR, 5.33 [2.88-9.86]; P  <  0.01). When moderate-deep sedation during anesthesia recovery was a covariate, both CI (OR, 3.02[1.60-5.70]; P  <  0.01) and moderate-deep sedation (OR, 3.94[2.19-7.11]; P  <  0.01) were associated with delirium. In multivariable analysis, postoperative pulmonary complications were associated with moderate-deep sedation (OR, 2.14[1.18-3.87]; P  = 0 .01) but not with CI (OR, 1.49 [0.76-2.92]; P  = 0 .25).

CONCLUSIONS

Cognitive impairment was associated with higher rates of moderate-deep residual sedation during anesthesia recovery and delirium, while moderate-deep sedation was associated with higher rates of pulmonary complications and delirium. We speculate that tailoring the anesthetic to facilitate faster emergence for CI patients could improve complication rates.

Is hospitalisation a risk factor for cognitive decline in the elderly?

PURPOSE OF REVIEW

Cognitive decline is frequently reported after hospitalisation in the contexts of surgery, delirium and critical care. The question not adequately addressed is whether all types of acute hospitalisations increase the risk of cognitive decline. As acute hospitalisations are common in the elderly, who are also vulnerable to cognitive decline, this possible association is of significant concern.

RECENT FINDINGS

This review summarises cognitive outcomes from recent observational studies investigating acute hospitalisation (emergent and elective) in older age adults. Studies were identified from searching Medline, Embase and PsycINFO databases and citations lists. The highest incidence of cognitive decline has been reported following critical care admissions and admissions complicated by delirium, although all types of acute hospitalisations are implicated. Age is the most consistent risk factor for cognitive decline. Several etiological and therapeutic aspects are being investigated, particularly the measurement of inflammatory biomarkers and treatment with anti-inflammatory medications.

SUMMARY

Acute hospitalisation for any reason appears to increase the risk of cognitive decline in older adults, but the cause remains elusive. Future research must clarify the nature and modifiers of posthospitalisation cognitive change, a priority in the face of an ageing population.

A toolbox for the longitudinal assessment of healthspan in aging mice

The number of people aged over 65 is expected to double in the next 30 years. For many, living longer will mean spending more years with the burdens of chronic diseases such as Alzheimer's disease, cardiovascular disease, and diabetes. Although researchers have made rapid progress in developing geroprotective interventions that target mechanisms of aging and delay or prevent the onset of multiple concurrent age-related diseases, a lack of standardized techniques to assess healthspan in preclinical murine studies has resulted in reduced reproducibility and slow progress. To overcome this, major centers in Europe and the United States skilled in healthspan analysis came together to agree on a toolbox of techniques that can be used to consistently assess the healthspan of mice. Here, we describe the agreed toolbox, which contains protocols for echocardiography, novel object recognition, grip strength, rotarod, glucose tolerance test (GTT) and insulin tolerance test (ITT), body composition, and energy expenditure. The protocols can be performed longitudinally in the same mouse over a period of 4-6 weeks to test how candidate geroprotectors affect cardiac, cognitive, neuromuscular, and metabolic health.

Perioperative Neurocognitive Disorder: State of the Preclinical Science

The purpose of this article is to provide a succinct summary of the different experimental approaches that have been used in preclinical postoperative cognitive dysfunction research, and an overview of the knowledge that has accrued. This is not intended to be a comprehensive review, but rather is intended to highlight how the many different approaches have contributed to our understanding of postoperative cognitive dysfunction, and to identify knowledge gaps to be filled by further research. The authors have organized this report by the level of experimental and systems complexity, starting with molecular and cellular approaches, then moving to intact invertebrates and vertebrate animal models. In addition, the authors' goal is to improve the quality and consistency of postoperative cognitive dysfunction and perioperative neurocognitive disorder research by promoting optimal study design, enhanced transparency, and "best practices" in experimental design and reporting to increase the likelihood of corroborating results. Thus, the authors conclude with general guidelines for designing, conducting and reporting perioperative neurocognitive disorder rodent research.

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.