Age-Related Perioperative Neurocognitive Disorders: Experimental Models and Druggable Targets

A comparison of large language model-generated and published perioperative neurocognitive disorder recommendations: a cross-sectional web-based analysis

BACKGROUND

Perioperative neurocognitive disorders (PNDs) are common complications after surgery and anaesthesia, particularly in older adults, leading to increased morbidity, mortality, and healthcare costs. Therefore, major medical societies have developed recommendations for the prevention and treatment of PNDs. Our study evaluated the reliability of large language models, specifically ChatGPT-4 and Gemini, in generating recommendations for PND management and comparing them with published guidelines.

METHODS

We conducted an online cross-sectional web-based analysis over 48 h in June 2024. Artificial intelligence (AI)-generated recommendations were produced in six different locations across five countries (Switzerland, Belgium, Turkey, Canada, and the East and West Coasts of the USA). The English prompt 'a table of a bundle of care for perioperative neurocognitive disorders' was entered into ChatGPT-4 and Gemini, generating tables evaluated by independent reviewers. The primary outcomes were the Total Disagreement Score (TDS) and Quality Assessment of Medical Artificial Intelligence (QAMAI), which compared AI-generated recommendations with published guidelines.

RESULTS

The study generated 14 tables, with TDS and QAMAI scores showing similar results for ChatGPT-4 and Gemini (2 [1-3] vs 2 [2-3], P=0.636 and 4 [4-4] vs 4 [3-4], P=0.424, respectively). AI-generated recommendations aligned well with published guidelines, with the highest alignment observed in ChatGPT-4-generated recommendations. No complete agreement with guidelines was achieved, and lack of cited sources was a noted limitation.

CONCLUSIONS

Large language models can generate perioperative neurocognitive disorder recommendations that align closely with published guidelines. However, further validation and integration of clinician feedback are required before clinical application.

Anesthesia/surgery leads to blood-brain barrier disruption via the transcellular and paracellular pathways, and postoperative delirium-like behavior: A comparative study in mice of different ages

AIMS

Postoperative delirium (POD) is a common complication of anesthesia and surgery, with a higher incidence in elderly patients. Disruption of the blood-brain barrier (BBB) is considered one of the key mechanisms underlying POD. Therefore, the present study aimed to investigate the effects of different BBB permeability alteration pathways on POD in mice of various ages.

METHODS

C57BL/6 J mice aged 4 and 16 months underwent exploratory laparotomy under sevoflurane anesthesia. Behavioral tests were conducted 24 h prior to surgery, as well as 6, 9, and 24 h postoperatively. Frontal cortex tissue was collected to detect the levels of BBB-related proteins and mRNA.

RESULTS

At 6 and 9 h after anesthesia/surgery, 4-month-old mice showed poorer performance on behavioral tests than their untreated counterparts. However, 16-month-old mice exhibited worse behavioral test results at 6, 9, and 24 h after surgery. Anesthesia/surgery 6 h postoperatively increased the expression of vesicle-associated proteins, and BBB leakage in 4-month-old mice. In 16-month-old mice, anesthesia/surgery altered the expression of tight junction proteins, vesicle-associated proteins, and BBB leakage at 6 and 24 h postoperatively.

CONCLUSION

Overall, our results suggest that anesthesia/surgery leads to age-dependent cognitive decline, and is associated with differences in the BBB injury pathways among mice of different ages. The transcellular pathway (transcytosis), compared to the paracellular pathway (tight junction), is more vulnerable to damage following anesthesia/surgery. This study provides new evidence for the improvement of POD through protection of the BBB.

Neuroprotection of celastrol against postoperative cognitive dysfunction through dampening cGAS-STING signaling

Neuroinflammation is a central player in postoperative cognitive dysfunction (POCD), an intractable and highly confounding neurological complication with finite therapeutic options. Celastrol, a quinone methide triterpenoid, is a bioactive ingredient extracted from Tripterygium wilfordii with talented anti-inflammatory capacity. However, it is unclear whether celastrol can prevent anesthesia/surgery-evoked cognitive deficits in an inflammation-specific manner. The STING agonist 5,6-dimethylxanthenone-4-acetic acid (DMXAA) was used to determine whether celastrol possesses neuroprotection dependent on the STING pathway in vivo and in vitro. Isoflurane and laparotomy triggered cGAS-STING activation, caspase-3/GSDME-dependent pyroptosis, and enhanced Iba-1 immunoreactivity. Celastrol improved cognitive performance and decreased the levels of cGAS, 2'3'-cGAMP, STING, NF-κB phosphorylation, Iba-1, TNF-α, IL-6, and IFN-β. Downregulation of cleaved caspase-3 and N-GSDME was observed in the hippocampus of POCD mice and HT22 cells after celastrol administration, accompanied by limited secretion of pyroptosis-pertinent pro-inflammatory cytokines IL-1β and IL-18. DMXAA neutralized the favorable influences of celastrol on cognitive function, as confirmed by the activation of the STING/caspase-3/GSDME axis. These findings implicate celastrol as a therapeutic agent for POCD through anti-inflammation and anti-pyroptosis.

Decoding paradoxical links of cytokine markers in cognition: Cross talk between physiology, inflammaging, and Alzheimer's disease- related cognitive decline

Recent research has revolutionized our understanding of memory consolidation by emphasizing the critical role of astrocytes, microglia, and immune cells in through cytokine signaling. Cytokines, compact proteins, play pivotal roles in neuronal development, synaptic transmission, and normal aging. This review explores the cellular mechanisms contributing to cognitive decline in inflammaging and Alzheimer's disease, highlighting the paradoxical effects of most studied cytokines (IL-1, IL-6, TNF-α) in brain function, which act as a double-edged sword in brain physiology, acting both as facilitators of healthy cognitive function and as a potential contributor to cognitive decline.

Pharmacological inhibition of cGAS ameliorates postoperative cognitive dysfunction by suppressing caspase-3/GSDME-dependent pyroptosis

Neuroinflammation is a major driver of postoperative cognitive dysfunction (POCD). The cyclic GMP-AMP synthase-stimulator of interferon gene (cGAS-STING) signaling is a prominent alarming device for aberrant double-stranded DNA (dsDNA) that has emerged as a key mediator of neuroinflammation in cognitive-related diseases. However, the role of the cGAS-STING pathway in the pathogenesis of POCD remains unclear. A POCD model was developed in male C57BL/6J mice by laparotomy under isoflurane (Iso) anesthesia. The cGAS inhibitor RU.521 and caspase-3 agonist Raptinal were delivered by intraperitoneal administration. BV2 cells were exposed to Iso and lipopolysaccharide (LPS) in the absence or presence of RU.521, and then cocultured with HT22 cells in the absence or presence of Raptinal. Cognitive function was assessed using the Morris water maze test and novel object recognition test. Immunofluorescence assays were used to observe the colocalization of dsDNA and cGAS. The downstream proteins and pro-inflammatory cytokines were detected using the Western blot and enzyme-linked immunosorbent assay (ELISA). Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining was used to assess the degree of cell death in the hippocampus following anesthesia/surgery treatment. Isoflurane/laparotomy and Iso + LPS significantly augmented the levels of cGAS in the hippocampus and BV2 cells, accompanied by mislocalized dsDNA accumulation in the cytoplasm. RU.521 alleviated cognitive impairment, diminished the levels of 2'3'-cGAMP, cGAS, STING, phosphorylated NF-κB p65 and NF-κB-pertinent pro-inflammatory cytokines (TNFα and IL-6), and repressed pyroptosis-associated elements containing cleaved caspase-3, N-GSDME, IL-1β and IL-18. These phenotypes could be rescued by Raptinal in vivo and in vitro. These findings suggest that pharmacological inhibition of cGAS mitigates neuroinflammatory burden of POCD by dampening caspase-3/GSDME-dependent pyroptosis, providing a potential therapeutic strategy for POCD.

Gaps in cognitive care among older patients undergoing spine surgery

INTRODUCTION

Among older adults undergoing surgery, postoperative delirium is the most common complication. Cognitive impairment and dementia are major risk factors for postoperative delirium, yet they are frequently under-recognized. It is well established that applying delirium preventive interventions to at-risk individuals can reduce the likelihood of delirium by up to 40%. The aim of this study was to evaluate how often delirium preventive interventions are missing in patients at risk for delirium due to baseline cognitive impairment.

METHODS

We conducted a retrospective study using data from the observational study Perioperative Anesthesia Neurocognitive Disorder Assessment-Geriatric (PANDA-G) and clinical data from the University of California San Francisco delirium prevention bundle. Patients age 65+ received preoperative multidomain cognitive assessment as part of a research protocol prior to undergoing inpatient spine surgery at a single major academic institution. Results of the cognitive testing were not available to clinical teams. Using electronic medical records, we evaluated if patients who were cognitively impaired at baseline received delirium prevention orders, sleep orders, and avoidance of AGS Beers Criteria® potentially inappropriate medications.

RESULTS

Of the 245 patients included in the study, 42% were women. The mean [SD] age was 72 [5.2] years. Preoperative cognitive impairment was identified in 40% of participants (N = 98), and of these, 34% had postoperative delirium. Of patients with preoperative cognitive impairment, 45% did not receive delirium preventive orders, 43% received PIMs, and 49% were missing sleep orders. At least one of the three delirium preventive interventions was missing in 70% of the patients.

DISCUSSION

Undiagnosed preoperative cognitive impairment among older adults undergoing spine surgery is common. When cognitive test results were not available to clinicians, patients with baseline cognitive impairment frequently did not receive evidence-based delirium preventive interventions. These findings highlight an opportunity to improve perioperative brain health care via preoperative cognitive assessment and clinical communication.

α5GABAA receptor: A potential therapeutic target for perioperative neurocognitive disorders, a review of preclinical studies

Perioperative neurocognitive disorders (PND) are a common complication in elderly patients following surgery, which not only prolongs the recovery period but also affects their future quality of life and imposes a significant burden on their family and society. Multiple factors, including aging, vulnerability, anesthetic drugs, cerebral oxygen desaturation, and severe pain, have been associated with PND. Unfortunately, no effective drug is currently available to prevent PND. α5 γ-aminobutyric acid subtype A (α5GABAA) receptors have been implicated in cognitive function modulation. Positive or negative allosteric modulators of α5GABAA receptors have been found to improve cognitive impairment under different conditions. Therefore, targeting α5GABAA receptors may represent a promising treatment strategy for PND. This review focuses on preclinical studies of α5GABAA receptors and the risk factors associated with PND, primarily including aging, anesthetics, and neuroinflammation. Specifically, positive allosteric modulators of α5GABAA receptors have improved cognitive function in aged experimental animals. In contrast, negative allosteric modulators of α5GABAA receptors have been found to facilitate cognitive recovery in aged or adult experimental animals undergoing anesthesia and surgery but not in aged experimental animals under anesthesia alone. The reasons for the discordant findings have yet to be elucidated. In preclinical studies, different strategies of drug administration, as well as various behavioral tests, may influence the stability of the results. These issues need to be carefully considered in future studies.

Peripheral inflammation and neurocognitive impairment: correlations, underlying mechanisms, and therapeutic implications

Cognitive impairments, such as learning and memory deficits, may occur in susceptible populations including the elderly and patients who are chronically ill or have experienced stressful events, including surgery, infection, and trauma. Accumulating lines of evidence suggested that peripheral inflammation featured by the recruitment of peripheral immune cells and the release of pro-inflammatory cytokines may be activated during aging and these conditions, participating in peripheral immune system-brain communication. Lots of progress has been achieved in deciphering the core bridging mechanism connecting peripheral inflammation and cognitive impairments, which may be helpful in developing early diagnosis, prognosis evaluation, and prevention methods based on peripheral blood circulation system sampling and intervention. In this review, we summarized the evolving evidence on the prevalence of peripheral inflammation-associated neurocognitive impairments and discussed the research advances in the underlying mechanisms. We also highlighted the prevention and treatment strategies against peripheral inflammation-associated cognitive dysfunction.

Association between postoperative delirium and adverse outcomes in older surgical patients: A systematic review and meta-analysis

STUDY OBJECTIVE

To assess the incidence of postoperative delirium and its outcomes in older non-cardiac surgical patients.

DESIGN

A systematic review and meta-analysis with multiple databases searched from inception to February 22, 2022.

SETTING

Postoperative assessments.

PATIENTS

Non-cardiac and non-neurological surgical patients aged ≥60 years with and without postoperative delirium. Included studies must report ≥1 postoperative outcome. Studies with a small sample size (N < 100 subjects) were excluded.

MEASUREMENTS

Outcomes comprised the pooled incidence of postoperative delirium and its postoperative outcomes, including mortality, complications, unplanned intensive care unit admissions, length of stay, and non-home discharge. For dichotomous and continuous outcomes, OR and difference in means were computed, respectively, with a 95% CI.

MAIN RESULTS

Fifty-four studies (20,988 patients, 31 elective studies, 23 emergency studies) were included. The pooled incidence of postoperative delirium was 19% (95% CI: 16%, 23%) after elective surgery and 32% (95% CI: 25%, 39%) after emergency surgery. In elective surgery, postoperative delirium was associated with increased mortality at 1-month (OR: 6.60; 95% CI: 1.58, 27.66), 6-month (OR: 5.69; 95% CI: 2.33, 13.88), and 1-year (OR: 2.87; 95% CI: 1.63, 5.06). The odds of postoperative complications, unplanned intensive care unit admissions, prolonged length of hospital stay, and non-home discharge were also higher in delirium cases. In emergency surgery, patients with postoperative delirium had greater odds of mortality at 1-month (OR: 3.56; 95% CI: 1.77, 7.15), 6-month (OR: 2.60; 95% CI: 1.88, 3.61), and 1-year (OR: 2.30; 95% CI: 1.77, 3.00).

CONCLUSIONS

Postoperative delirium was associated with higher odds of mortality, postoperative complications, unplanned intensive care unit admissions, length of hospital stay, and non-home discharge. Prevention and perioperative management of delirium may optimize surgical outcomes.

Gut microbiota in perioperative neurocognitive disorders: current evidence and future directions

Perioperative neurocognitive disorders (PND) is a common surgical anesthesia complication characterized by impairment of memory, attention, language understanding and social ability, which can lead to a decline in the quality of life of patients, prolong the hospitalization period and increase the mortality rate. PND has a high incidence rate, which has a great impact on postoperative recovery and quality of life of patients, and has caused a heavy economic burden to society and families. In recent years, PND has become an important public health problem. The high risk population of PND is more prone to gut microbiota imbalance, and gut microbiota may also affect the inflammatory response of the central nervous system through the microbiota-gut-brain axis. Meanwhile, Neuroinflammation and immune activation are important mechanisms of PND. Regulating gut microbiota through probiotics or fecal bacteria transplantation can significantly reduce neuroinflammation, reduce the abnormal activation of immune system and prevent the occurrence of PND. This review summarizes the research progress of gut microbiota and PND, providing basis for the prevention and treatment of PND.

Defining the role of Interleukin-6 for the development of perioperative neurocognitive disorders: Evidence from clinical and preclinical studies

For most, staying "mentally sharp" as they age is a very high priority that may be thwarted by the consequences of a postoperative complication unrelated to the disorder which necessitated the surgical intervention. Perioperative neurocognitive disorder (PND) is an overarching term for cognitive impairment in surgical patients, that includes conditions from delirium to dementia, affecting more than 7 million patients annually in the US, and which threatens both functional independence and life. Clinical trials and meta-analyses have identified the association between PNDs and increased perioperative levels of Interleukin-6 (IL-6), a pleiotropic cytokine that is both necessary and sufficient for postoperative memory decline in a preclinical model of PND. Recently, we reported that, in adult male wild-type mice subjected to tibial fracture under general anesthesia, IL-6 trans-signaling in hippocampal CA1 neurons mediates surgery-induced memory impairment. As there are no therapeutic options for preventing or reversing PNDs, patients and their caregivers, as well as the healthcare industry, endure staggering costs. Olamkicept, a highly selective IL-6 trans-signaling blocker has shown to be efficacious and safe in clinical trials involving patients with inflammatory bowel disease, another condition for which IL-6 trans-signaling is the mediating mechanism. Subject to a demonstration that olamkicept is effective in preventing cognitive impairment in vulnerable (aged and Alzheimer's Disease) preclinical PND models, clinical trials involving aged and/or cognitively impaired surgical patients should be undertaken to study olamkicept's utility for PNDs.