Effects of perioperative cognitive function training on postoperative cognitive dysfunction and postoperative delirium: a systematic review and meta-analysis.

Postoperative cognitive dysfunction (POCD) and postoperative delirium (POD) are common post-surgical complications that often lead to prolonged hospitalization, reduced quality of life, increased healthcare costs, and increased patient mortality. We conducted a meta-analysis to evaluate the effects of preoperative cognitive function training on postoperative cognitive function. PubMed, Cochrane Library, Embase, Web of Science, ClinicalTrials, China National Knowledge Infrastructure, Wanfang Database, VIP Database, and Chinese Biomedical Literature Database were searched for randomized controlled trials comparing the effects of preoperative cognitive function training and conventional preoperative measures on postoperative cognitive function. The search period spanned from the establishment of the databases to March 31, 2023. The primary outcomes were the incidence of POCD and POD. Eleven randomized controlled trials involving 1,045 patients were included. The results of the meta-analysis showed that, compared to the control group, preoperative cognitive function training significantly reduced the incidence of POCD (RR = 0.38, P < 0.00001), and there was no statistically significant difference in the incidence of POD (P = 0.3). Cognitive function training significantly improved postoperative cognitive function scores compared with the control group (MD = 1.92, P = 0.001). In addition, two studies reported that 10% of the patients in the cognitive training group completed a pre-set training duration. Cognitive function training significantly reduced the incidence of POCD; however, there was no significant difference in the incidence of POD. Preoperative cognitive function training should be promoted and emphasized as a simple, economical, and practical method of improving postoperative cognitive function. https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=396154.

Postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) are common and serious complications in elderly surgical patients, especially after prolonged procedures. Recent evidence suggests that the depth of anaesthesia may influence the risk of these adverse outcomes. This meta-analysis examined whether light versus deep anaesthesia affects the incidence of POD and POCD, as well as recovery measures such as time to post-anaesthesia care unit (PACU) discharge and length of hospital stay in elderly patients. A systematic search identified randomized controlled trials (RCTs) published in English up to May 24, 2025, involving patients aged ≥60 years undergoing major surgery. The outcomes evaluated were POD, POCD, PACU discharge time, and hospital stay. Meta-analyses were conducted using random- or fixed-effects models based on heterogeneity. Eight RCTs with a total of 1,957 elderly patients were included. Light anaesthesia was associated with a significantly lower incidence of POD (OR = 0.52; 95% CI: 0.41-0.66; P < 0.00001; I² = 0%). The incidence of POCD was also reduced with light anaesthesia (OR = 0.55; 95% CI: 0.39-0.77; P = 0.0005; I² = 15%). Time to PACU discharge was shorter under light anaesthesia (mean difference (MD) = -9.43 minutes; 95% CI: -12.87 to -5.99; P < 0.00001; I² = 66%). Although hospital stay showed a trend favouring light anaesthesia (MD = -0.81 days; 95% CI: -1.85 to 0.24; P = 0.13), this result was not statistically significant (I² = 89%). Overall, light anaesthesia appears to reduce the incidence of POD and POCD and is associated with faster early recovery in elderly surgical patients. The observed trend toward shorter hospital stays did not reach significance. These findings indicate potential benefits of lighter anaesthetic strategies, though they should not be interpreted as evidence of direct causation, as other factors such as anaesthetic drug type and surgical invasiveness may also contribute.

Postoperative cognitive dysfunction (POCD) and postoperative delirium (POD) are common postoperative complications in elderly patients. The effect of anesthesia depth on cognitive function remains unknown. We aimed to assess the correlations between anesthesia depth, cognitive function, and inflammation. Literature searches were conducted on Web of Science, PubMed, EMBASE, and Cochrane libraries until August 2019. All studies were randomized controlled trials (RCTs). The STATA 15.0 and trial sequential analysis (TSA) version 0.9.5.10 beta software were used for data analysis. POD and POCD were calculated using a random-effects model. The combined effect estimates are expressed as risk ratios (RR) with 95% confidence intervals (CI). Ten RCTs involving 3142 patients met inclusion criteria. The meta-analysis indicated that the incidence of POCD in the light anesthesia group was significantly lower than the deep anesthesia group on days 1 (RR=0.14, 95% CI: 0.04 to 0.45; I2=0.00, P>0.10), and 90 (RR=0.72, 95% CI: 0.54 to 0.96; I2=0.00,P>0.10). Light anesthesia significantly reduced the risk of POD (RR=0.69, 95% CI: 0.58 to 0.82; I2=0.00, P>0.10). There was no statistical difference in the Mini-Mental State Examination score between the groups on postoperative day 1 (standardized mean difference (SMD)= 0.04, 95% CI: -0.25 to 0.33; I2=0.00, P>0.10).The TSA found that there was insufficient evidence on the effect of anesthesia depth on POCD, but that the conclusions on POD were reliable. Light anesthesia was associated with a decrease in POD and may promote better neurocognitive function postoperatively in comparison with deep anesthesia.

IntroductionCognitive changes after anaesthesia and surgery, such as delirium and postoperative cognitive dysfunction (POCD), are common and lead to poor outcomes and increased healthcare costs. While several interventions for delirium...

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

Effect of goal-directed fluid therapy on early cognitive function in elderly patients with spinal stenosis: A Case-Control Study

Postoperative delirium (POD), emergence delirium (ED), and postoperative cognitive dysfunction (POCD) are disorders of the neuropsychiatric spectrum affecting the elderly during the postoperative period, potentially sharing a common pathophysiological pathway. Disrupted sleep postoperatively correlates with both POD and POCD, revealing overlapping risk factors. This study investigates the potential of dexmedetomidine anesthesia to reduce the incidence of POD (primary outcome), ED, POCD, impairment of sleep quality, and emergent chronic pain (secondary outcomes) in older adults undergoing major orthopedic surgery under regional anesthesia. In this double-blind randomized control trial, patients scheduled for major lower limb orthopedic surgery under regional anesthesia were randomized to receive either dexmedetomidine or propofol for sedation at a 1:1 ratio. POD, ED, and POCD were assessed with the Confusion Assessment Method tool, the Riker Sedation-Agitation scale, and the European Battery of psychometric tests, respectively. Sleep quality was assessed using the Pittsburg Sleep Quality Index and chronic pain with the painDETECT tool. Assessments of all outcome variables were performed before surgery, and at 48 hours and 3 months postoperatively. A total of 80 patients (dexmedetomidine group n = 41) were enrolled in the study and completed the follow-up. POD, ED, and early POCD incidence were significantly lower in dexmedetomidine compared to propofol group (4.8% vs 38.4%, P = .001; 2.4% vs 38.4%, P < .001; 2.4% vs 56.4%, P < .001, respectively). Patients in the dexmedetomidine group reported improved sleep quality in the immediate postoperative period (lower PSQI score) and lower painDETECT scores at 3 months (4.4 ± 0.7 vs 13.4 ± 0.8, P < .001; 2.4 ± 0.9 vs 5.3 ± 0.9, P = .023, respectively). Intraoperative bradycardia and hemodynamic instability episodes were more common in the dexmedetomidine group while a single patient presented airway obstruction (2.4% vs 30.8%, P = .002) in the dexmedetomidine group. Sedation with dexmedetomidine resulted in a statistically and clinically important reduction in the incidence of POD, ED, and early POCD, while it improved self-reported postoperative sleep quality and reduced chronic pain scores in patients undergoing major elective lower limb surgery under regional anesthesia.

Introduction: Cardiac surgery anesthesia is associated with risks such as postoperative delirium (POD) and stress-related responses. Benzodiazepines have been used perioperatively to reduce anxiety and enhance hemodynamic stability. However, their use may increase the risk of delirium, especially in older adults. Hypothesis: This systematic review and meta-analysis aim to assess the effect of perioperative benzodiazepine use on the incidence of POD in patients undergoing cardiac surgery. Methods: We systematically searched PubMed, Embase, and Cochrane Central for randomized-controlled trials (RCTs) and observational studies comparing benzodiazepines to placebo or non-benzodiazepine drugs in adults undergoing cardiac surgery. The primary outcome was POD. Secondary outcomes included Mini Mental State Examination Score (MMSE), length of intensive care unit (ICU), and time to extubation. For dichotomous outcomes, odds ratios (ORs) with 95% confidence intervals (CIs) were calculated, while mean differences (MDs) were used for continuous outcomes. All statistical analyses were performed using R software version 4.4.3. Results: Eight studies were included, comprising 36,301 patients, of whom 20,747 (68.5%) received benzodiazepines. The prescription of benzodiazepines was associated with similar incidence of POD compared to the control group (OR 1.05; 95% CI: 0.88 to 1.25; p=0.55; I 2 =83%; Figure 1). Similarly, there were no significant difference in MMSE score (MD -0.11; 95% CI: -3.17 to 2.95; p=0.94; I 2 =70%), ICU length of stay (MD 4.72 hours; 95% CI: -1.37 to 10.80; p=0.13; I 2 =99%), and time to extubation (MD -0.53 hours; 95% CI: -2.16 to 1.09; p=0.52; I 2 =72%) between the two protocols as shown in Figure 2. Conclusion: This meta-analysis found no significant association between perioperative benzodiazepine use and the incidence of POD in adults undergoing cardiac surgery. Additionally, no significant differences were observed in MMSE scores, ICU length of stay, or time to extubation.

Bispectral Index (BIS) Monitoring and Postoperative Delirium in Elderly Patients Undergoing Surgery: A Systematic Review and Meta-Analysis With Trial Sequential Analysis

The present study was conducted to compare the effect of memory and cognitive strategies training on vocabulary learning of intermediate proficiency group of Iranian learners of English as a foreign language. It is to check how memory and cognitive strategies training affect word learning of EFL intermediate learners (N=60) who were homogenized by the Nelson proficiency test (Nelson 250 B). They were divided into two experimental groups. For omitting the words learners know, pre test of vocabulary was taken. Also a questionnaire adapted by Rezaee et al (2004) based on Kudo’ (1999) work with the reliability of 0.92 was taken to deduce not only their familiarity of strategies but also their knowledge of strategies uses. In the first experimental group, 30 students were trained to use memory strategies (keyword and semantic map) in word learning and in the other experimental group, the other 30 students were taught to learn the same new English words through cognitive training (flashcards and repetition). The course consisted of 11 sessions (two two-hour sessions per week). At the end the data was collected using a teacher made test as the post test (including 60 open ended items). The results of the independent t-test shown that there is no significant difference between the effect of cognitive and memory strategy training on intermediate EFL learners’ word learning. In general, the finding suggests that memory strategies training and cognitive strategy training respectively enhance memory and cognitive strategy uses.

Perioperative dexmedetomidine administration to prevent delirium in adults after non-cardiac surgery: A systematic review and meta-analysis

Purpose Postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) are common complications in surgical patients, which contribute to longer hospital stays, poorer functional outcomes and reduced quality of life. As a potential intervention to address this significant burden, remote ischemic conditioning (RIC)—a low cost, non-invasive therapy involving inducing brief cycles of ischemia and reperfusion—has gained interest. The aim of this systematic review and meta-analysis was to synthesise current evidence on the effects of perioperative RIC on neurocognitive outcomes. Methods This systematic review was conducted in accordance with PRISMA guidelines and was registered with PROSPERO (CRD420251041823). A literature search was performed using MEDLINE, Embase, and Web of science from inception to March 16, 2025. Eligible studies included randomized controlled trials (RCTs) assessing the use of perioperative RIC in human adults (≥ 18 years of age) undergoing surgery. Outcomes of interest included incidence of POD and POCD, and performance on global and domain-specific cognitive measures (e.g., Mini Mental State Examination [MMSE], Montreal Cognitive Assessment [MoCA], and Trail Making Test [TMT]). Study screening, data extraction, and risk of bias assessment using the Cochrane risk of bias tool (ROB-2) were performed by independent reviewers. The DerSimonian-Laird model was used to analyze outcomes, while study heterogeneity was evaluated using Cochran’s Q. Results Out of 4,664 records screened, 16 publications from 15 RCTs (2,912 patients) were included. POD incidence at &lt; 30 days (odds ratio [OR]: 0.77, 95% confidence interval [CI] 0.50 to 1.20, n = 6), POCD incidence at &lt; 30 days (OR: 0.79, 95% CI 0.53 to 1.20, n = 5) and POCD incidence at ≥ 30 days groups (OR: 1.06, 95% CI 0.62 to 1.80, n = 3) were not significantly different between groups. Conversely, patients who received RIC had better MoCA (standardized mean difference [SMD] = 0.48, 95% CI 0.19 to 0.76, n = 2), Stroop test part 1 (SMD = 0.38, 95% CI 0.13 to 0.64, n = 2) and part 2 (SMD = 0.26, 95% CI 0.05 to 0.48, n = 2) scores at &lt; 30 days, and better MMSE (SMD = 1.16, 95% CI 0.81 to 1.50, n = 2) scores at ≥ 30 days. RIC did not significantly improve TMT A and B completion time, Digit Symbol Substitution Test scores, Stroop part 3, Verbal Fluency Test semantic/phonemic, digit span forward/backward, and immediate/delayed verbal memory at any time point. Conclusion We found no support for a preventative effect of perioperative RIC on the incidence of short- and long-term post-operative neurocognitive disorders. Whereas there was no clear benefit of RIC for domain-specific cognitive performance, results indicated the intervention may improve global cognitive function, although there were only a limited number of trials in this regard.

Effects of cognitive training in Parkinson's disease: A randomized controlled trial

Objective To analyze the incidence and risk factors of postoperative delirium (POD) in patients with glioma and to explore the association between WHO (World Health Organization) tumor grades and POD. Methods A second analysis of clinical data from 113 adult glioma patients in a single-center, prospective cohort study of 800 neurosurgery patients was conducted from March 2017 to February 2018 at Department of Critical Medicine (ICU), Beijing Tiantan Hospital, Capital Medical University. Patients were assessed for delirium on the first to third days post surgery (twice a day) using the Richmond Agitation-Sedation Scale (RASS) and Confusion Assessment Method for the ICU (CAM-ICU). The patient was divided into delirium group (43 cases) and non-delirium group (70 cases) by whether the patient had had delirium. We collected the patient’s general preoperative information, preoperative condition, early postoperative clinical data, and neurosurgical specialty data (including WHO grades) as potential risk factors that may be associated with the occurrence of POD. The independent risk factors of POD were identified using multivariate logistic regression analysis. In particular, the relationship between WHO glioma grade and POD was explored. Results In 113 glioma patients who were admitted to the ICU for routine postoperative monitoring, the incidence of POD was 38.1% (43/113). The incidence of POD in patients with WHO grade Ⅰ-Ⅳ gliomas increased with the increase of the WHO grade: 7.7% (1/13), 14.3% (3/21), 22.7% (5/22) and 63.0% (34/57). Among the potential risk factors, age (OR=1.08, 95% CI: 1.04-1.13, P<0.001), GCS (Glasgow coma scale) score at admission to ICU (OR=0.80, 95% CI: 0.71-0.90, P<0.001) and the WHO grade of tumor (OR=2.01, 95% CI: 1.03-3.92, P=0.041) was independent risk factors for POD. Conclusions The WHO grade of glioma is an independent risk factor for POD. With the increase of tumor grade, the incidence of POD also increases. Key words: Glioma; Neurosurgical procedures; Delirium; Neoplasm grading; Compensa-tory neuroplasticity

To the Editor, We read with interest the randomized trial by Zhang et al[1] entitled “Effect of remimazolam on postoperative delirium in elderly patients undergoing major abdominal surgery: a randomized controlled Trial.” The use of blinded assessors with twice-daily validated assessments and reporting of both intention-to-treat (ITT) and per-protocol (PP) analyses are notable strengths. While postoperative delirium (POD) incidence did not differ significantly between groups [PP: 17.1% vs 19.7%; odds ratio (OR) 1.189, 95% confidence interval (CI) 0.688–2.057], and intraoperative hypotension appeared less frequent with remimazolam, we seek clarification on several points to aid interpretation, particularly given the variability of POD incidence across cohorts (10% reported in elective major abdominal surgery)[2]. First, although the trial was designed as a non-inferiority study (margin 5%, one-sided α = 0.025), the results are largely presented in terms of “no significant difference” based on P-values. For non-inferiority trials, interpretation hinges on the prespecified estimand and its CI relative to the margin. We suggest explicitly reporting the between-group risk difference and its 97.5% confidence interval in both ITT and PP populations, and stating clearly whether the upper confidence bound lies within the 5% margin. A simple figure showing the point estimate and confidence interval against the margin would further aid readers. Second, in the ITT population, baseline imbalances were reported for education level and diabetes – both plausibly related to cognitive reserve and POD risk. Although subsequent analyses identified education, American Society of Anesthesiologists (ASA) grade, age, and Mini-Mental State Examination (MMSE) as prognostic factors, it would be helpful to assess whether these imbalances materially affect the treatment estimate. We therefore suggest a covariate-adjusted sensitivity analysis (e.g., regression including education, diabetes, age, ASA grade, and MMSE) and reporting the adjusted effect alongside the primary analysis, particularly given an overall POD incidence of around 20%. This request is supported by cohort evidence linking education and perioperative vulnerability to POD risk[2–4] (college education: adjusted OR 0.35, 95% CI 0.13–0.91; ASA ≥3: OR 2.0, 95% CI 1.0–3.9). Third, the prespecified subgroup finding in patients aged ≥75 years is notable, with a significant interaction term (P for interaction <0.001) suggesting a higher POD risk with remimazolam. To fully appreciate the clinical relevance of this signal, readers would benefit from seeing the absolute POD rates and the corresponding absolute risk difference within this specific subgroup. Furthermore, as subgroup analyses are inherently sensitive to event counts and multiple testing, cautious interpretation is warranted. Age thresholds show strong associations with POD risk in prospective cohorts; for example, age ≥75 years independently increased POD risk (adjusted risk ratio (RR) 2.54, 95% CI 1.11–5.80) in a noncardiac surgery cohort[5]. Clarifying the interaction in this high-risk demographic is crucial for safe clinical application. Fourth, anesthetic depth was guided by bispectral index (BIS) targets (40–60). The manuscript appropriately acknowledges the uncertainty regarding BIS interpretation under remimazolam. If BIS values do not correspond equivalently to hypnotic depth across different agents, maintaining “similar BIS” may not ensure comparable cortical suppression. This has profound implications for both delirium risk assessment and the interpretation of hemodynamic outcomes. Data on total hypnotic drug doses or alternative depth-of-anesthesia metrics, if available, could provide valuable context. If BIS values under remimazolam reflect a different hypnotic state than under propofol, maintaining “similar BIS” might have resulted in disparate actual anesthesia depths, potentially confounding the comparison of delirium risk. Finally, methodologically, the handling of missing data through last observation carried forward (LOCF) and hot-deck imputation in ITT analyses, along with the exclusion of a notable proportion of patients (22/370) from PP analyses due to additional medications, raises questions about the robustness of the findings. The sensitivity of the primary conclusion to these assumptions, as well as the context of real-world co-interventions, would be valuable to discuss. Additionally, while POD assessment through postoperative day 5 captures most early cases, later-onset delirium associated with complications, ICU transfer, or sleep disruption might be missed, particularly with earlier discharge. This represents a recognized limitation in many POD studies. Moreover, hemodynamic “variability” (not merely the presence of hypotension) has been linked to POD in cohort evidence; for instance, mean arterial pressure variability was associated with POD severity (MAP variance OR 1.038 per 10 units, 95% CI 1.013–1.065) in a prospective cohort[6]. This trial offers valuable prospective evidence on the safety profile of remimazolam in elderly surgical populations. Addressing the aforementioned points would not only clarify the interpretation of the current data but also better guide the design of future trials and the optimization of anesthetic strategies for this novel agent in vulnerable geriatric patients. Ethical approval Not applicable. Consent Not applicable.