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

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.

Comparison of regional vs. general anesthesia on the risk of dementia: a systematic review and meta-analysis

Background

Dementia is a gradual and ongoing cognitive decline due to damage to nerve cells in the brain. This meta-analysis aimed to assess the potential relationship between regional anesthesia (RA) and the risk of dementia.

Methods

Electronic databases including Embase, Medline, Google Scholar, and Cochrane Library were searched for studies investigating the association between RA and dementia risk from inception to March 2022. The primary outcome was the risk of dementia in patients who underwent RA (RA group) and those who received general anesthesia (GA group). Secondary outcomes included identifying other potential risk factors for dementia and comparing dementia risk between individuals receiving RA and those not receiving surgery/anesthesia (placebo group).

Results

Eight cohort studies published between 2014 and 2023 were included in this analysis. A meta-analysis of the available data demonstrated no differences in baseline characteristics and morbidities (i.e., age, male proportion, hypertension, diabetes, depression, and severe comorbidities) between the RA and GA groups (all p > 0.05). Initial analysis revealed that the risk of dementia was higher in the GA group than in the RA group (HR = 1.81, 95% CI = 1.29-2.55, p = 0.007, I 2 = 99%, five studies). However, when a study featuring a relatively younger population was excluded from the sensitivity analysis, the results showed a similar risk of dementia (HR, 1.17; p = 0.13) between the GA and RA groups. The pooled results revealed no difference in dementia risk between the RA and placebo groups (HR = 1.2, 95% CI = 0.69-2.07, p = 0.52, I 2 = 68%, three studies). Sensitivity analysis revealed that the evidence was not stable, suggesting that limited datasets precluded strong conclusions on this outcome. Anxiety, stroke history, hypertension, diabetes, hyperlipidemia, and diabetes are potential predictors of dementia.

Conclusion

Our results emphasize that, while RA could be protective against dementia risk compared to GA, the association between the type of anesthesia and dementia risk might vary among different age groups. Owing to the significant prevalence of dementia among older people and their surgical needs, further investigations are warranted to clarify the association between dementia risk and regional anesthesia.Systematic review registration: https://www.crd.york.ac.uk/prospero/, CRD42023411324.

Association between surgery and rate of incident dementia in older adults: A population-based retrospective cohort study

BACKGROUND

The risk of incident dementia after surgery in older adults is unclear. The study objective was to examine the rate of incident dementia among older adults after elective surgery compared with a matched nonsurgical control group.

METHODS

We conducted a population-based, propensity-matched retrospective cohort study using data from linked administrative databases in Ontario, Canada. All community-dwelling individuals aged 66 years and older who underwent one of five major elective surgeries between April 1, 2007 and March 31, 2011 were included. Each surgical patient was matched 1:1 on surgical specialty of the surgeon at consultation, age, sex, fiscal year of entry, and propensity score with a patient who attended an outpatient visit with a surgeon of the same surgical specialty but did not undergo surgery. Patients were followed for up to 5 years after cohort entry for the occurrence of a new dementia diagnosis, defined from administrative data. Cause-specific hazard models were used to estimate the hazard ratio (HR) and 95% confidence interval (CI) for the association between surgery and the hazard of incident dementia. Subgroup and sensitivity analyses were performed.

RESULTS

A total of 27,878 individuals (13,939 matched pairs) were included in the analysis. A total of 640 (4.6%) individuals in the surgical group and 965 (6.9%) individuals in the control group developed dementia over the 5-year follow-up period. Individuals who underwent surgery had a reduced rate of incident dementia compared with their matched nonsurgical controls (HR 0.88; 95% CI 0.80-0.97; p = 0.01). This association was persistent in most subgroups and after sensitivity analyses.

CONCLUSIONS

Elective surgery did not increase the rate of incident dementia when compared with matched nonsurgical controls. This could be an important consideration for patients and surgeons when elective surgery is considered.

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 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.

Dementia risk amongst older adults with hip fracture receiving general anaesthesia or regional anaesthesia: a propensity-score-matched population-based cohort study

BACKGROUND

Preclinical studies have indicated that anaesthesia is an independent risk factor for dementia, but the clinical associations between dementia and different types of general anaesthesia or regional anaesthesia remain unclear. We conducted a population-based cohort study using propensity-score matching to compare dementia incidence in patients included in the Taiwanese National Health Insurance Research Database who received various anaesthetic types for hip fracture surgery.

METHODS

Patients aged ≥65 yr who received elective hip fracture surgery from 2002 to 2019 were divided into three groups receiving either inhalational anaesthesia (GA), total intravenous anaesthesia-general anaesthesia (TIVA-GA), or regional anaesthesia (RA), and matched in a 1:1 ratio. The incidence rates of dementia were then determined.

RESULTS

Propensity-score matching yielded 89 338 patients in each group (N=268 014). Dementia incidence rates in the inhalational GA, TIVA-GA, and RA groups were 4821, 3400, and 2692 per 100 000 person-years, respectively. The dementia incidence rate ratio (95% confidence interval [CI]) for inhalational GA to TIVA-GA was 1.19 (1.14-1.25), for inhalational GA to RA was 1.51 (1.15-1.66), and for TIVA-GA to RA was 1.28 (1.09-1.51).

CONCLUSIONS

The incidence rate ratios of dementia amongst older adults undergoing hip fracture surgery were higher for those receiving general anaesthesia than for those receiving regional anaesthesia, with inhalational anaesthesia associated with a higher incidence rate ratio for dementia than total intravenous anaesthesia (TIVA).

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).

Extended anesthesia exposure for abdominal and pelvic procedures in older adults with colorectal cancer: Associations with chart dementia diagnoses

BACKGROUND

We hypothesized that cumulative anesthesia exposure over the course of routine treatment of colorectal cancer in older adults can increase long-term risk of Alzheimer's disease (AD), Alzheimer's disease-related dementias (ADRD), and other chronic neurocognitive disorders (CND).

METHODS

We conducted a SEER-Medicare-based retrospective cohort study of 84,770 individuals age 65 years and older diagnosed with colorectal cancer between 1998 and 2007 using a proportional hazards model with inverse probability weighted estimators. The primary exploratory variable was a time-variant measure of cumulative anesthesia exposure for abdominal and pelvic procedures, updated continuously.

RESULTS

Our primary outcomes, AD and ADRD, occurred in 6005/84,770 (7.1%) and 14,414/83,444 (17.3%) individuals respectively. No statistically significant association was found between cumulative anesthesia exposure and AD (hazard ratio [HR], 0.993; 95% CI, 0.973-1.013). However, it was moderately associated with the risk of ADRD (HR, 1.016; 95% CI, 1.004-1.029) and some secondary outcomes including most notably: cerebral degeneration (HR, 1.048; 95% CI, 1.033-1.063), hepatic encephalopathy (HR, 1.133; 95% CI, 1.101-1.167), encephalopathy-not elsewhere classified (HR,1.095; 95% CI: 1.076-1.115), and incident/perioperative delirium (HR, 1.022; 95% CI, 1.012-1.032). Furthermore, we observed an association between perioperative delirium and increased risk of AD (HR, 2.05; 95% CI, 1.92-2.09).

CONCLUSION

Cumulative anesthesia exposure for abdominal and pelvic procedures was not associated with increased risk of AD directly and had a small but statistically significant association with ADRD and a number of other CNDs. Cumulative anesthesia exposure was also associated with perioperative delirium, which had an independent adverse association with AD risk.

Risk of Dementia According to Surgery Type: A Nationwide Cohort Study

The relationship between dementia and surgery remains unclear. Research to elucidate the relationship between them is scarce, and conducting epidemiological research is complicated. This study aimed to investigate the incidence and risk of dementia according to the surgery type. We performed a retrospective propensity score-matched cohort study using nationwide representative cohort sample data from the Korean National Health Insurance Service in South Korea between 2003 and 2004. Incidence rates for dementia were obtained by dividing the number of patients with dementia by person-years at risk. To identify the risk of dementia according to the type of surgery, we investigated the hazard ratio by each surgery type. The incidence rates of dementia in control, musculoskeletal, and two or more surgeries groups were 9.66, 13.47, and 13.36 cases per 1000 person-years, respectively. The risk of dementia in the musculoskeletal and two or more surgeries groups was 1.44-fold higher (95% confidence interval (95% CI), 1.22–1.70) and 1.42-fold higher (95% CI, 1.17–1.72) than that in the control group, respectively. Patients who underwent musculoskeletal surgery and two or more surgeries had a higher risk of dementia; however, there was no association with the type of anesthesia administered.

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.

[Perioperative Medicine in Visceral Surgery in the Elderly Patient from an Anaesthesiological Perspective]

Demographic change is leading to an increasing number of old patients both in our society and in hospitals. With increasing age, not only the number of pre-existing conditions increases, but also the postoperative complication rate and mortality. Ultimately, however, it is not age that is decisive, but the condition of the patient and his or her capacity to face the physical and mental challenges of a surgical procedure. Frail patients are particularly at risk of complications, and an essential strategy - known as prehabilitation - is to put them in a better state pre-operatively through physical and mental training, as well as nutritional counselling. Delirium is one of the most frequent postoperative complications. Measures such as refraining from premedication with benzodiazepines, measuring the depth of anaesthesia, refraining from long-acting opioids, performing fast-track surgery, and providing glasses/hearing aids quickly postoperatively can reduce the risk of delirium. Close interdisciplinary consultation between surgeons, anaesthetists, geriatricians and physiotherapists is essential to coordinate the perioperative procedure and reduce the perioperative risk for elderly patients.

Prevention of postoperative delirium through the avoidance of potentially inappropriate medications in a geriatric surgical patient

We demonstrate the utility of risk stratification for postoperative delirium in geriatric patients and show that postoperative delirium can be prevented in high-risk patients when potentially inappropriate medications (PIMs) (medications that are best avoided in older adults) are avoided. In this case, a 65-year-old woman underwent two debridement procedures with similar presurgical risk for postoperative delirium. There was no risk stratification or preoperative cognitive assessment in the first procedure, she received PIMs and developed postoperative delirium. In the second procedure, PIMs were intentionally avoided and postoperative delirium did not occur. This case supports recent recommendations from the European Society of Anaesthesiology, the American Society of Anesthesiologists and the American Geriatrics Society that providers assess a patient's cognitive function and delirium risk profile preoperatively to appropriately guide perioperative management.

A synthetic peptide rescues rat cortical neurons from anesthetic-induced cell death, perturbation of growth and synaptic assembly

Anesthetics are deemed necessary for all major surgical procedures. However, they have also been found to exert neurotoxic effects when tested on various experimental models, but the underlying mechanisms remain unknown. Earlier studies have implicated mitochondrial fragmentation as a potential target of anesthetic-induced toxicity, although clinical strategies to protect their structure and function remain sparse. Here, we sought to determine if preserving mitochondrial networks with a non-toxic, short-life synthetic peptide—P110, would protect cortical neurons against both inhalational and intravenous anesthetic-induced neurotoxicity. This study provides the first direct and comparative account of three key anesthetics (desflurane, propofol, and ketamine) when used under identical conditions, and demonstrates their impact on neonatal, rat cortical neuronal viability, neurite outgrowth and synaptic assembly. Furthermore, we discovered that inhibiting Fis1-mediated mitochondrial fission reverses anesthetic-induced aberrations in an agent-specific manner. This study underscores the importance of designing mitigation strategies invoking mitochondria-mediated protection from anesthetic-induced toxicity in both animals and humans.