The role of apolipoprotein E in cognitive decline and delirium after bypass heart operations

Apolipoprotein E4 allele is genetically associated with risk of the short- and medium-term postoperative cognitive dysfunction: A meta-analysis and trial sequential analysis

The aim of systematic review and meta-analysis was to investigate whether APOE4 was associated with postoperative neurologic dysfunction occurrence in short- or medium-term among surgical patients and to study the potential genetic association among these two entities. We searched electronic databases for reserch studies to evaluate the association of APOE4 with postoperative delirium (POD) or short- and medium term postoperative cognitive dysfunction (POCD). Twenty-two trials (16 prospective and six retrospective) with 6734 patients were included. APOE4 alleles was shown significantly associated with POCD within 1 week (odds ratio, OR, 1.89, 95% confidence interval, CI, 1.36 to 2.6278, p < 0.01) in the random-effects model. A significant association was also noted between APOE4 and POCD in medium-term, 1-3 months, after surgery (OR: 1.67, 95% CI: 1.003-2.839, p = 0.049). However, APOE4 was not significantly associated with POCD 1 year after surgery (OR: 0.98, 95% CI: 0.57-1.70, p = 0.9449) and POD (OR: 1.28, 95% CI: 0.85-1.91, p = 0.23). In conclusion, APOE4 alleles was genetically associated with short- and medium-term postoperative neurological dysfunction and future screening or preventive strategies derived is highly potential to improve outcomes.

ATPase Inhibitory Factor 1 Is Critical for Regulating Sevoflurane-Induced Microglial Inflammatory Responses and Caspase-3 Activation

Postoperative delirium (POD) is one of the most important complications after surgery with general anesthesia, for which the neurotoxicity of general anesthetics is a high-risk factor. However, the mechanism remains largely unknown, which also hinders the effective treatment of POD. Here, we confirmed that a clinical concentration of the general anesthetic sevoflurane increased the expression of inflammatory factors and activated the caspase-3 by upregulating ATPase inhibitory factor 1 (ATPIF1) expression in microglia. Upregulation of ATPIF1 decreased the synthesis of ATP which is an important signaling molecule secreted by microglia. Extracellular supplementation with ATP attenuated the microglial inflammatory response and caspase-3 activation caused by sevoflurane or overexpression of ATPIF1. Additionally, the microglial inflammatory response further upregulated ATPIF1 expression, resulting in a positive feedback loop. Animal experiments further indicated that intraperitoneal injection of ATP significantly alleviated sevoflurane anesthesia-induced POD-related anxiety behavior and memory damage in mice. This study reveals that ATPIF1, an important protein regulating ATP synthesis, mediates sevoflurane-induced neurotoxicity in microglia. ATP supplementation may be a potential clinical treatment to alleviate sevoflurane-induced POD.

Biomarkers in delirium: A systematic review

BACKGROUND

Delirium is a common neuropsychiatric disorder associated with prolonged hospital stays, and increased morbidity and mortality. Diagnosis is frequently missed due to varying disease presentation and lack of standardized testing. We examined biomarkers as diagnostic or prognostic indicators of delirium, and provide a rational basis for future studies.

METHOD

Systematic review of literature published between Jan 2000 and June 2019. Searches included: PubMed; Web of Science; CINAHL; EMBASE; COCHRANE and Medline. Additional studies were identified by searching bibliographies of eligible articles.

RESULTS

2082 relevant papers were identified from all sources. Seventy-three met the inclusion criteria, all of which were observational. These assessed a range of fourteen biomarkers. All papers included were in the English language. Assessment methods varied between studies, including: DSM criteria; Confusion Assessment Method (CAM) or CAM-Intensive Care Unit (ICU). Delirium severity was measured using the Delirium Rating Scale (DRS). Delirium was secondary to post-operative dysfunction or acute medical conditions.

CONCLUSION

Evidence does not currently support the use of any one biomarker. However, certain markers were associated with promising results and may warrant evaluation in future studies. Heterogeneity across study methods may have contributed to inconclusive results, and more clarity may arise from standardization of methods of clinical assessment. Adjusting for comorbidities may improve understanding of the pathophysiology of delirium, in particular the role of confounders such as inflammation, cognitive disorders and surgical trauma. Future research may also benefit from inclusion of other diagnostic modalities such as EEG as well as analysis of genetic or epigenetic factors.

The complex interaction of genetics and delirium: a systematic review and meta-analysis

The objective is to understand genetic predisposition to delirium. Following PRISMA guidelines, we undertook a systematic review of studies involving delirium and genetics in the databases of Pubmed, Scopus, Cochrane Library and PsycINFO, and performed a meta-analysis when appropriate. We evaluated 111 articles, of which 25 were finally included in the analysis. The studies were assessed by two independent researchers for methodological quality using the Downs and Black Tool and for genetic analysis quality. We performed a meta-analysis of 10 studies of the Apolipoprotein E (APOE) gene, obtaining no association with the presence of delirium (LOR 0.18, 95% CI - 0.10-0.47, p = 0.21). Notably, only 5 out of 25 articles met established criteria for genetic studies (good quality) and 6 were of moderate quality. Seven studies found an association with APOE4, the dopamine transporter gene SCL6A3, dopamine receptor 2 gene, glucocorticoid receptor, melatonin receptor and mitochondrial DNA haplotypes. One genome-wide association study found two suggestive long intergenic non-coding RNA genes. Five studies found no association with catechol-o-methyltransferase, melatonin receptor or several interleukins genes. The studies were heterogenous in establishing the presence of delirium. Future studies with large samples should further specify the delirium phenotype and deepen our understanding of interactions between genes and other biological factors.

Risk Factors for Delirium and Cognitive Decline Following Coronary Artery Bypass Grafting Surgery: A Systematic Review and Meta-Analysis

Background

Coronary artery bypass grafting (CABG) is known to improve heart function and quality of life, while rates of surgery‐related mortality are low. However, delirium and cognitive decline are common complications. We sought to identify preoperative, intraoperative, and postoperative risk or protective factors associated with delirium and cognitive decline (across time) in patients undergoing CABG.

Methods and Results

We conducted a systematic search of Medline, PsycINFO, EMBASE, and Cochrane (March 26, 2019) for peer‐reviewed, English publications reporting post‐CABG delirium or cognitive decline data, for at least one risk factor. Random‐effects meta‐analyses estimated pooled odds ratio for categorical data and mean difference or standardized mean difference for continuous data. Ninety‐seven studies, comprising data from 60 479 patients who underwent CABG, were included. Moderate to large and statistically significant risk factors for delirium were as follows: (1) preoperative cognitive impairment, depression, stroke history, and higher European System for Cardiac Operative Risk Evaluation (EuroSCORE) score, (2) intraoperative increase in intubation time, and (3) postoperative presence of arrythmia and increased days in the intensive care unit; higher preoperative cognitive performance was protective for delirium. Moderate to large and statistically significant risk factors for acute cognitive decline were as follows: (1) preoperative depression and older age, (2) intraoperative increase in intubation time, and (3) postoperative presence of delirium and increased days in the intensive care unit. Presence of depression preoperatively was a moderate risk factor for midterm (1–6 months) post‐CABG cognitive decline.

Conclusions

This meta‐analysis identified several key risk factors for delirium and cognitive decline following CABG, most of which are nonmodifiable. Future research should target preoperative risk factors, such as depression or cognitive impairment, which are potentially modifiable.

Registration

URL: https://www.crd.york.ac.uk/prosp​ero/; Unique identifier: CRD42020149276.

Anesthesia and surgery induce age-dependent changes in behaviors and microbiota

The neuropathogenesis of postoperative delirium remains mostly unknown. The gut microbiota is implicated in the pathogenesis of neurological disorders. We, therefore, set out to determine whether anesthesia/surgery causes age-dependent gut microbiota dysbiosis, changes in brain IL-6 level and mitochondrial function, leading to postoperative delirium-like behavior in mice. Female 9 or 18 months old mice received abdominal surgery under 1.4% isoflurane for two hours. The postoperative delirium-like behavior, gut microbiota, levels of brain IL-6, PSD-95 and synaptophysin, and mitochondrial function were determined by a battery of behavioral tests, 16s rRNA sequencing, ELISA, Western blot and Seahorse XFp Extracellular Flux Analyzer. Intragastric administration of Lactobacillus (10 days) and probiotic (20 days) were used to mitigate the anesthesia/surgery-induced changes. Anesthesia/surgery caused different alterations in gut microbiota, including change rate of reduction in the levels of gut lactobacillus, between the 18 and 9 months old mice. The anesthesia/surgery induced greater postoperative delirium-like behavior, increased brain IL-6 levels, decreased PSD-95 and synaptophysin levels, and mitochondrial dysfunction in 18 than 9 months old mice. Treatments with Lactobacillus and probiotic mitigated the anesthesia/surgery-induced changes. These data suggest that microbiota dysbiosis may contribute to neuropathogenesis of postoperative delirium and treatment with Lactobacillus or a probiotic could mitigate postoperative delirium.

Apolipoprotein E genotype and the association between C-reactive protein and postoperative delirium: Importance of gene-protein interactions

INTRODUCTION

Apolipoprotein E (APOE) status may modify the risk of postoperative delirium conferred by inflammation.

METHODS

We tested whether APOE modifies the established association between C-reactive protein (CRP) and delirium incidence, severity, and duration in 553 noncardiac surgical patients aged 70 and older. High postoperative plasma CRP (≥234.12 mg/L) was defined by the highest sample-based quartile. Delirium was determined using the Confusion Assessment Method and chart review, and severity was determined by the Confusion Assessment Method-Severity score.

RESULTS

APOE ε4 carrier prevalence was 19%, and postoperative delirium occurred in 24%. The relationship between CRP and delirium incidence, severity, and duration differed by ε4 status. Among ε4 carriers, there was a strong relationship between high CRP (vs. low CRP) and delirium incidence (relative risk [95% confidence interval], 3.0 [1.4-6.7]); however, no significant association was observed among non-ε4 carriers (relative risk [95% CI], 1.2 [0.8-1.7]).

DISCUSSION

Our findings raise the possibility that APOE ε4 carrier status may modify the relationship between postoperative day 2 CRP levels and postoperative delirium.

Postoperative delirium after hysteroscopy in young woman: A case report

RATIONALE

Postoperative delirium is extremely rare in young women and in minimally invasive endoscopic surgeries in gynecology and obstetrics. It greatly affects both physicians and patients. This report presents a special case of postoperative delirium after hysteroscopy in a young woman and a literature review of the associated etiology, diagnosis, and treatment.

PATIENT CONCERNS

A 39-year-old woman was admitted to the gynecology ward following irregular vaginal bleeding for 3 months and an intrauterine space-occupying lesion for 1 week. Hysteroscopy, endometrial polypectomy, and fractional curettage procedures were successfully performed; however, the patient became unresponsive after surgery.

DIAGNOSIS

Postoperative delirium.

INTERVENTIONS

Sedatives and vasoactive medicines, such as dexmedetomidine, midazolam, and dopamine were administered for maintenance treatment.

OUTCOMES

The patients gradually regained consciousness.

LESSONS

Physicians should attach importance and improvise effective clinical management strategies for postoperative delirium based on clinical specialty characteristics and related guidelines.

State of the clinical science of perioperative brain health: report from the American Society of Anesthesiologists Brain Health Initiative Summit 2018

Cognitive recovery after anaesthesia and surgery is a concern for older adults, their families, and caregivers. Reports of patients who were 'never the same' prompted a scientific inquiry into the nature of what patients have experienced. In June 2018, the ASA Brain Health Initiative held a summit to discuss the state of the science on perioperative cognition, and to create an implementation plan for patients and providers leveraging the current evidence. This group included representatives from the AARP (formerly the American Association of Retired Persons), American College of Surgeons, American Heart Association, and Alzheimer's Association Perioperative Cognition and Delirium Professional Interest Area. This paper summarises the state of the relevant clinical science, including risk factors, identification and diagnosis, prognosis, disparities, outcomes, and treatment of perioperative neurocognitive disorders. Finally, we discuss gaps in current knowledge with suggestions for future directions and opportunities for clinical and translational projects.

Risk Factors for Postoperative Delirium After Gastrectomy in Gastric Cancer Patients

PURPOSE

The incidence of postoperative delirium is reported to range from 9 to 87%; however, no report has focused on cases of postoperative delirium in gastric cancer surgery alone. Therefore, we investigated the incidence of and risk factors for postoperative delirium after gastrectomy in patients with gastric cancer.

METHODS

A total of 1037 patients who underwent surgery were included in the study. Patients were divided into two groups-those with (delirium group) or without (non-delirium group) postoperative delirium-and their backgrounds were compared. The short-term outcomes and the overall survival were also investigated.

RESULTS

Postoperative delirium was observed in 47 of 1037 patients (4.5%). A multivariate analysis revealed that male gender, age ≥ 75 years, a history of cerebrovascular disease, and the habitual use of sleeping pills were independent predictive factors for postoperative delirium. The postoperative hospital stay was significantly longer in the postoperative delirium group than in the non-delirium group. Postoperative delirium was significantly associated with postoperative complications. The 3-year overall survival was 74.3% in the delirium group and 85.5% in the non-delirium group (log-rank p = 0.006). A multivariate analysis revealed that postoperative delirium was an independent prognostic factor, along with the age and cancer stage.

CONCLUSION

The incidence of postoperative delirium was 4.5% in gastric cancer patients. Male gender, age ≥ 75 years, a history of cerebrovascular disease, and the habitual use of narcoleptic agents were risk factors for postoperative delirium after gastrectomy in gastric cancer patients. Postoperative delirium was strongly associated with other postoperative complications and a poor survival after surgery.

Neurocognitive Function after Cardiac Surgery: From Phenotypes to Mechanisms

For half a century, it has been known that some patients experience neurocognitive dysfunction after cardiac surgery; however, defining its incidence, course, and causes remains challenging and controversial. Various terms have been used to describe neurocognitive dysfunction at different times after cardiac surgery, ranging from "postoperative delirium" to "postoperative cognitive dysfunction or decline." Delirium is a clinical diagnosis included in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Postoperative cognitive dysfunction is not included in the DSM-5 and has been heterogeneously defined, though a recent international nomenclature effort has proposed standardized definitions for it. Here, the authors discuss pathophysiologic mechanisms that may underlie these complications, review the literature on methods to prevent them, and discuss novel approaches to understand their etiology that may lead to novel treatment strategies. Future studies should measure both delirium and postoperative cognitive dysfunction to help clarify the relationship between these important postoperative complications.

Fish Oil Supplementation Does Not Affect Cognitive Outcomes in Cardiac Surgery Patients in the Omega-3 Fatty Acids for Prevention of Post-Operative Atrial Fibrillation (OPERA) Trial

Background

Cognitive decline has been reported following cardiac surgery, leading to great interest in interventions to minimize its occurrence. Long-chain n-3 (ω-3) polyunsaturated fatty acids (PUFAs) have been associated with less cognitive decline in observational studies, yet no trials have tested the effects of n-3 PUFAs on cognitive decline after surgery.

Objective

We sought to determine whether perioperative n-3 PUFA supplementation reduces postoperative cognitive decline in patients postcardiac surgery.

Methods

The study comprised a randomized, double-blind, placebo-controlled, multicenter, clinical trial conducted on cardiac surgery recipients at 9 tertiary care medical centers across the United States. Patients were randomly assigned to receive fish oil (1-g capsules containing ≥840 mg n-3 PUFAs as ethyl esters) or placebo, with preoperative loading of 8-10 g over 2-5 d followed postoperatively by 2 g/d until hospital discharge or postoperative day 10, whichever came first. Global cognition was assessed using in-person testing over 30 d with the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) (primary outcome), Mini-Mental State Exam (secondary outcome), and Trails A and B (secondary outcome) tests. All end points were prespecified. Statistical methods were employed, including descriptive statistics, logistic regression, and various sensitivity analyses.

Results

A total of 320 US patients were enrolled in the Omega-3 Fatty Acids for Prevention of Post-Operative Atrial Fibrillation (OPERA) Cognitive Trial (OCT), a substudy of OPERA. The median age was 62 y (IQR 53, 70 y). No differences in global cognition were observed between placebo and fish oil groups at day 30 (P = 0.32) for the primary outcome, a composite neuropsychological RBANS score. The population demonstrated resolution of initial 4-d cognitive decline back to baseline function by 30 d on the RBANS.

Conclusion

Perioperative supplementation with n-3 PUFAs in cardiac surgical patients did not influence cognition ≤30 d after discharge. Modern anesthetic, surgical, and postoperative care may be mitigating previously observed long-term declines in cognitive function following cardiac surgery. This trial was registered at clinicaltrials.gov as NCT00970489.

Cerebrospinal Fluid Apolipoprotein E Levels in Delirium

Background/Aims

Delirium and the apolipoprotein E ε4 allele are risk factors for late-onset Alzheimer disease (LOAD), but the connection is unclear. We looked for an association.

Methods

Inpatients with delirium (n = 18) were compared with LOAD outpatients (n = 19), assaying blood and cerebrospinal fluid (CSF) using multiplex ELISA.

Results

The patients with delirium had a higher Confusion Assessment Method (CAM) score (5.6 ± 1.2 vs. 0.0 ± 0.0; p < 0.001) and Delirium Index (13.1 ± 4.0 vs. 2.9 ± 1.2; p = 0.001) but a lower Mini-Mental State Examination (MMSE) score (14.3 ± 6.8 vs. 20.8 ± 4.6; p = 0.003). There was a reduction in absolute CSF apolipoprotein E level during delirium (median [interquartile range]: 9.55 μg/mL [5.65–15.05] vs. 16.86 μg/mL [14.82–20.88]; p = 0.016) but no differences in apolipoprotein A1, B, C3, H, and J. There were no differences in blood apolipoprotein levels, and no correlations between blood and CSF apolipoprotein levels. CSF apolipoprotein E correlated negatively with the CAM score (r = −0.354; p = 0.034) and Delirium Index (r = −0.341; p = 0.042) but not with the Acute Physiology and Chronic Health Evaluation (APACHE) index, or the MMSE or Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE).

Conclusion

Reduced CSF apolipoprotein E levels during delirium may be a mechanistic link between two important risk factors for LOAD.

A systematic review and meta-analysis of the association between the apolipoprotein E genotype and delirium

The role of apolipoprotein E (APOE) in Alzheimer's disease and other dementias has been investigated intensively. However, the relationship between APOE and delirium has only recently been explored in studies that have included relatively small samples. A meta-analysis of the published pooled data is timely to explore the relationship between APOE and delirium and to inform further research in this topic. PubMed, EBSCOhost, Google Scholar, Scopus, all EBM Reviews (OVID) and the Cochrane Database of Systematic Reviews were searched with relevant keywords and from the references of relevant papers. Ten papers were found that examined the relationship between APOE and delirium. Data were extracted from eight of them and pooled for meta-analysis using random effects with R software. Data from 1762 participants, of whom 479 (27.2%) were diagnosed with delirium, showed low heterogeneity (Q=13.11, d.f.=7, P=0.07; I=44.86%). The possession of the APOE ε4 allele has a small (log odds ratio: 0.18, 95% confidence interval: 0.23-0.59), nonsignificant (P=0.38) effect on the presence of delirium. No publication bias was identified. The metapower of the pooled data was low (α=0.05, power=0.65). On analysing the studies to date, it seems that there is no association between APOE and the occurrence of delirium. We suggest that further studies are needed with greater number of patients to clarify any association as well as to examine for other patterns of association including relevance for subgroups of patients who develop delirium and for effects on the phenotype of delirium and the outcomes.

Neurodevelopmental Outcomes in Children With Congenital Heart Disease-What Can We Impact?

OBJECTIVES

The objectives of this review are to discuss the scope of neurologic injuries in newborns with congenital heart disease, the mechanisms of injury, including prenatal, pre-, intra-, and postoperative factors, neurodevelopmental outcomes, and therapeutic strategies for the timely intervention and prevention of neurologic injury.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSION

At the current time, important research is underway to 1) better understand the developing brain in the fetus with complex congenital heart disease, 2) to identify modifiable risk factors in the operating room and ICU to maximize long-term neurodevelopmental outcomes, and 3) develop strategies to improve family psychosocial health, childhood development, and health-related quality of life following hospital discharge. Crucial in this effort is the identification of an early postoperative surrogate variable with good predictive validity for long-term outcomes. If an appropriate surrogate variable for long-term outcomes can be identified, and measured relatively early after surgical intervention for complex congenital heart disease, reliable clinical trials can be undertaken to improve upon current outcomes.

Does Apolipoprotein E Genotype Increase Risk of Postoperative Delirium?

OBJECTIVE

To determine whether apolipoprotein E (ApoE) is associated with postoperative delirium incidence, severity, and duration in older patients free of dementia at baseline.

METHODS

The authors examined 557 nondemented patients aged 70 years or older undergoing major noncardiac surgery enrolled in the Successful Aging after Elective Surgery Study. Three ApoE measures were considered: ε2, ε4 carriers versus noncarriers, and a three-category ApoE measure. Delirium was determined using the Confusion Assessment Method (CAM) and chart review. We used generalized linear models to estimate the association between ApoE and delirium incidence, severity (peak CAM Severity [CAM-S] score), and days.

RESULTS

ApoE ε2 and ε4 was present in 15% and 19%, respectively, and postoperative delirium occurred in 24%. Among patients with delirium, the mean peak CAM-S score was 8.0 (standard deviation: 4), with most patients experiencing 1 or 2 delirium days (51% or 28%, respectively). After adjusting for age, sex, surgical procedure, and preoperative cognitive function, ApoE ε4 and ε2 carrier status were not associated with postoperative delirium: RR for ε4=1.0, 95% CI: 0.7-1.5 and RR for ε2=0.9, 95% CI: 0.6-1.4. No association between ApoE and delirium severity or number of delirium days was observed.

CONCLUSION

In older surgery patients free of dementia, our findings do not support the hypothesis that the ApoE genotype does not confer either risk or protection in postoperative delirium incidence, severity, or duration. Thus, an important genetic risk factor for Alzheimer disease does not affect risk of delirium.

Review of delirium in patients with Parkinson's disease

Parkinson's disease (PD) is common and has a number of associated neuropsychiatric disturbances. Of these, delirium has historically been under-recognised. Delirium is an acute disturbance of attention and awareness that fluctuates, and is accompanied by an additional disturbance of cognition. As delirium is known to carry a particularly poor prognosis in terms of morbidity and mortality, and the relationship between delirium and dementia is becoming better defined, we completed a literature review of delirium in the context of PD. A literature search was completed using the databases PubMed, Embase and Ovid Medline. PubMed (1945-2014) was searched in September 2014; Embase (1974-2014); and Ovid Medline (1946-2014) in October 2014. The search terms 'delirium' and 'Parkinsons' in combination were used. Large studies using a robust definition of delirium were lacking in PD. There is the suggestion that PD is a risk factor for delirium and that delirium negatively impacts upon the motor symptom trajectory. Deficits in the neurotransmitters dopamine and acetylcholine are implicated in the pathophysiology of delirium in PD. Systemic inflammation also appears to have a role. Treatment of delirium in PD should include medication review and cautious use of atypical antipsychotics where pharmacological treatment is indicated. Of the atypical antipsychotics studied, quetiapine has the least extrapyramidal side effects. Evidence suggests a specific link between delirium and PD but well-designed clinical studies to evaluate the prevalence, impact and treatment of delirium in PD are required. Given the potential to improve outcomes through delirium prevention we conclude that delirium in PD is an area worthy of further study.

Quantitative proteomics of delirium cerebrospinal fluid

Delirium is a common cause and complication of hospitalization in older people, being associated with higher risk of future dementia and progression of existing dementia. However relatively little data are available on which biochemical pathways are dysregulated in the brain during delirium episodes, whether there are protein expression changes common among delirium subjects and whether there are any changes which correlate with the severity of delirium. We now present the first proteomic analysis of delirium cerebrospinal fluid (CSF), and one of few studies exploring protein expression changes in delirium. More than 270 proteins were identified in two delirium cohorts, 16 of which were dysregulated in at least 8 of 17 delirium subjects compared with a mild Alzheimer's disease neurological control group, and 31 proteins were significantly correlated with cognitive scores (mini-mental state exam and acute physiology and chronic health evaluation III). Bioinformatics analyses revealed expression changes in several protein family groups, including apolipoproteins, secretogranins/chromogranins, clotting/fibrinolysis factors, serine protease inhibitors and acute-phase response elements. These data not only provide confirmatory evidence that the inflammatory response is a component of delirium, but also reveal dysregulation of protein expression in a number of novel and unexpected clusters of proteins, in particular the granins. Another surprising outcome of this work is the level of similarity of CSF protein profiles in delirium patients, given the diversity of causes of this syndrome. These data provide additional elements for consideration in the pathophysiology of delirium as well as potential biomarker candidates for delirium diagnosis.

The assessment of the T102C polymorphism of the 5HT2a receptor gene, 3723G/A polymorphism of the NMDA receptor 3A subunit gene (GRIN3A) and 421C/A polymorphism of the NMDA receptor 2B subunit gene (GRIN2B) among cardiac surgery patients with and without delirium

OBJECTIVE

The studies regarding the role of genes polymorphism in development of postoperative delirium are extremely rare. Therefore, we investigated the potential association of polymorphism in 5HT2a receptor gene and N-methyl-d-aspartate (NMDA) receptor 3A and 2B subunits genes with postoperative delirium.

METHOD

We conducted a prospective, nested, case-control study. For analysis, 3723 G/A (rs3739722) polymorphism in the GRIN3A gene, 421 C/A (rs3764028) polymorphism in the GRIN2B gene and T102C (rs6313) polymorphism in the 5HT2A gene were selected.

RESULTS

Genetic analysis confirmed that there were significant differences in genotype frequencies for 3723 G/A between delirium patients and controls. No other significant associations were observed. Moreover, according to the multivariate conditional logistic regression analysis the presence of AG haplotype of GRIN3A gene was independently associated with postoperative delirium.

CONCLUSIONS

These findings suggest that the genetic variations of NR3A subunit of NMDA receptor may be a predisposing factor to delirium among the Polish population of cardiac surgery patients.

Interleukin 6 and apolipoprotein E as predictors of acute brain dysfunction and survival in critical care patients

BACKGROUND

Delirium occurs in up to 80% of intensive care patients and is associated with poor outcomes. The biological cause of delirium remains elusive.

OBJECTIVES

To determine if delirium and recovery are associated with serum levels of interleukins and apolipoprotein E over time and with apolipoprotein E genotype.

METHODS

The sample consisted of 77 patients with no previous cognitive deficits who required mechanical ventilation for 24 to 96 hours. Daily serum samples were obtained for enzyme-linked immunosorbent assay measurements of interleukins 6, 8, and 10 and apolipoprotein E. DNA extracted from blood was analyzed for apolipoprotein E genotyping. The Confusion Assessment Method for the Intensive Care Unit was administered daily on days 2 through 9.

RESULTS

Among the 77 patients, 23% had no delirium, 46% experienced delirium, and 31% experienced coma. Additionally, 77% had delirium or coma (acute brain dysfunction), and compared with other patients, had fewer ventilator-free days (P = .03), longer stay (P = .04), higher care needs at discharge (P = .001), higher mortality (P = .02), and higher levels of interleukin 6 (P = .03), and the APOE*3/*3 apolipoprotein E genotype (P = .05). Serum levels of apolipoprotein E correlated with levels of interleukins 8 and 10. Patients with the E4 allele of apolipoprotein E had shorter duration of delirium (P = .02) and lower mortality (P = .03) than did patients without this allele.

CONCLUSIONS

Apolipoprotein E plays a complex role in illness response and recovery in critically ill patients. The relationship between apolipoprotein E genotype and brain dysfunction and survival is unclear.

Neuropathogenesis of delirium: review of current etiologic theories and common pathways

Delirium is a neurobehavioral syndrome caused by dysregulation of neuronal activity secondary to systemic disturbances. Over time, a number of theories have been proposed in an attempt to explain the processes leading to the development of delirium. Each proposed theory has focused on a specific mechanism or pathologic process (e.g., dopamine excess or acetylcholine deficiency theories), observational and experiential evidence (e.g., sleep deprivation, aging), or empirical data (e.g., specific pharmacologic agents' association with postoperative delirium, intraoperative hypoxia). This article represents a review of published literature and summarizes the top seven proposed theories and their interrelation. This review includes the "neuroinflammatory," "neuronal aging," "oxidative stress," "neurotransmitter deficiency," "neuroendocrine," "diurnal dysregulation," and "network disconnectivity" hypotheses. Most of these theories are complementary, rather than competing, with many areas of intersection and reciprocal influence. The literature suggests that many factors or mechanisms included in these theories lead to a final common outcome associated with an alteration in neurotransmitter synthesis, function, and/or availability that mediates the complex behavioral and cognitive changes observed in delirium. In general, the most commonly described neurotransmitter changes associated with delirium include deficiencies in acetylcholine and/or melatonin availability; excess in dopamine, norepinephrine, and/or glutamate release; and variable alterations (e.g., either a decreased or increased activity, depending on delirium presentation and cause) in serotonin, histamine, and/or γ-aminobutyric acid. In the end, it is unlikely that any one of these theories is fully capable of explaining the etiology or phenomenologic manifestations of delirium but rather that two or more of these, if not all, act together to lead to the biochemical derangement and, ultimately, to the complex cognitive and behavioral changes characteristic of delirium.

Association between APOE epsilon 4 allele and postoperative cognitive dysfunction: a meta-analysis

BACKGROUND

Carriers of the apolipoprotein E epsilon 4 allele (APOEε4) may be at increased risk of postoperative cognitive dysfunction (POCD), but this association has not been reported consistently. We conducted a meta-analysis to derive a more precise conclusion.

METHODS

The PubMed, EBSCO and EMBASE databases were searched for eligible studies published in English before March 2013. The association between APOEε4 and POCD was expressed by the odds ratio (OR) with 95% confidence interval (CI). Funnel plots were constructed and publication bias assessed by Egger's test.

RESULTS

Nine studies encompassing 1063 APOEε4 carriers and 2983 noncarriers were included. At about 1-week postsurgery, a significant association between APOEε4 and POCD was found (OR 1.83, 95% CI: 1.18-2.85), but the association was no longer significant after removing one large study (OR 1.35, 95% CI: 0.92-1.97). Stratified analysis of cardiac/vascular surgery patients also yielded no significant correlation (OR 1.62, 95% CI: 0.80-3.28). One to three months postsurgery, neither the overall analysis (OR 1.56, 95% CI: 0.87-2.81) nor the stratified analysis of cardiac/vascular surgery patients (OR 3.33, 95% CI: 0.55-20.22) indicated a significant correlation. APOEε4 was also not correlated with POCD at 1-year postsurgery (OR 1.15, 95% CI: 0.71-1.86). No evidence of publication bias was revealed by Egger's test.

CONCLUSIONS

The APOEε4 allele was associated with a significantly increased POCD risk about 1-week postsurgery, but the association depended on one large study. No association was found 1-3 months and 1-year postsurgery.

Delirium in the acute phase after stroke and the role of the apolipoprotein E gene

OBJECTIVE

To study the association between the epsilon 4 allele of apolipoprotein E (APOEε4) and delirium in a stroke population.

METHODS

527 consecutive stroke patients were screened for delirium during the first week of admission with the confusion assessment method. In three hundred fifty-three patients genomic DNA isolation was available.

RESULTS

The incidence of delirium after stroke in the 353 patients was 11.3%. There was no association between APOEε4 and delirium. Even after adjustment for IQCODE, stroke localization, stroke subtype, stroke severity, infection, and brain atrophy no association was found (odds ratio: 0.9; 95% confidence interval: 0.4-2.1). Delirium did not last longer in patients with an APOEε4 allele compared to patients without an APOEε4 allele (median: 5.6 days [range: 1-21] versus median: 4.6 days [range: 1-15], p = 0.5).

CONCLUSION

There was no association between the presence of an APOEε4 allele and the occurrence of delirium in the acute phase after stroke.

Predisposing and precipitating factors of delirium after cardiac surgery: a prospective observational cohort study

OBJECTIVE

To comprehensively assess pre-, intra-, and postoperative delirium risk factors as potential targets for intervention.

BACKGROUND

Delirium after cardiac surgery is associated with longer intensive care unit (ICU) stay, and poorer functional and cognitive outcomes. Reports on delirium risk factors so far did not cover the full range of patients' presurgical conditions, intraoperative factors, and postoperative course.

METHODS

After written informed consent, 221 consecutive patients ≥ 50 years scheduled for cardiac surgery were assessed for preoperative cognitive performance, and functional and physical status. Clinical and biochemical data were systematically recorded perioperatively.

RESULTS

Of the 215 patients remaining for analysis, 31% developed delirium in the intensive care unit. Using logistic regression models, older age [73.3 (71.2-75.4) vs 68.5 (67.0-70.0); P = 0.016], higher Charlson's comorbidity index [3.0 (1.5-4.0) vs 2.0 (1.0-3.0) points; P = 0.009], lower Mini-Mental State Examination (MMSE) score (MMSE, [27 (23-29) vs 28 (27-30) points; P = 0.021], length of cardiopulmonary bypass (CPB) [CPB; 133 (112-163) vs 119 (99-143) min; P = 0.004], and systemic inflammatory response syndrome in the intensive care unit [25 (36.2%) vs 13 (8.9%); P = 0.001] were independently associated with delirium. Combining age, MMSE score, Charlson's comorbidity index, and length of CPB in a regression equation allowed for a prediction of postoperative delirium with a sensitivity of 71.19% and a specificity of 76.26% (receiver operating analysis, area under the curve: 0.791; 95% confidence interval: 0.727-0.845).

CONCLUSIONS

Further research will evaluate if modification of these risk factors prevents delirium and improves outcomes.

Cognitive trajectories after postoperative delirium

BACKGROUND

Delirium is common after cardiac surgery and may be associated with long-term changes in cognitive function. We examined postoperative delirium and the cognitive trajectory during the first year after cardiac surgery.

METHODS

We enrolled 225 patients 60 years of age or older who were planning to undergo coronary-artery bypass grafting or valve replacement. Patients were assessed preoperatively, daily during hospitalization beginning on postoperative day 2, and at 1, 6, and 12 months after surgery. Cognitive function was assessed with the use of the Mini-Mental State Examination (MMSE; score range, 0 to 30, with lower scores indicating poorer performance). Delirium was diagnosed with the use of the Confusion Assessment Method. We examined performance on the MMSE in the first year after surgery, controlling for demographic characteristics, coexisting conditions, hospital, and surgery type.

RESULTS

The 103 participants (46%) in whom delirium developed postoperatively had lower preoperative mean MMSE scores than those in whom delirium did not develop (25.8 vs. 26.9, P<0.001). In adjusted models, those with delirium had a larger drop in cognitive function (as measured by the MMSE score) 2 days after surgery than did those without delirium (7.7 points vs. 2.1, P<0.001) and had significantly lower postoperative cognitive function than those without delirium, both at 1 month (mean MMSE score, 24.1 vs. 27.4; P<0.001) and at 1 year (25.2 vs. 27.2, P<0.001) after surgery. With adjustment for baseline differences, the between-group difference in mean MMSE scores was significant 30 days after surgery (P<0.001) but not at 6 or 12 months (P=0.056 for both). A higher percentage of patients with delirium than those without delirium had not returned to their preoperative baseline level at 6 months (40% vs. 24%, P=0.01), but the difference was not significant at 12 months (31% vs. 20%, P=0.055).

CONCLUSIONS

Delirium is associated with a significant decline in cognitive ability during the first year after cardiac surgery, with a trajectory characterized by an initial decline and prolonged impairment. (Funded by the Harvard Older Americans Independence Center and others.).

Ondasetron versus haloperidol for the treatment of postcardiotomy delirium: a prospective, randomized, double-blinded study

Background

To investigate the controlling efficacy of ondasetron and haloperidol in regard to the postcardiotomy delirium.

Methods

We included in this prospective, randomized, double-blinded study 80 patients who developed delirium after heart surgery with the application of heart lung-machine. The patients were divided into two, equally-sized groups, which on detection of delirium received ondasetron 8 mg iv or haloperidol 5 mg iv respectively. The statistical analysis compared the baseline and demographic characteristics of the two groups (age, gender, comorbidities, years of education, type of surgery etc.).

Results

Both ondasetron and haloperidol had very good delirium controlling effects, without statistically significant differences.

Discussion-Conclusions

Ondasetron and haloperidol are efficient agents as far as the treatment of postcardiotomy delirium is concerned. As, in addition, ondasetron bares milder side-effects, we believe this could be the agent of choice in patients developing postcardiotomy delirium in the future.

Biomarkers for delirium--a review

To improve delirium recognition and care, numerous serum biomarkers have been investigated as potential tools for risk stratification, diagnosis, monitoring, and prognostication of delirium. The literature was reviewed, and no evidence was found to support the clinical use of any delirium biomarker, although certain biomarkers such as S-100 beta and insulin-like growth factor-1 and inflammatory markers have shown some promising results that need to be evaluated in future studies with appropriate sample size, prospective designs, and in a more-generalizable population.

The association of the dopamine transporter gene and the dopamine receptor 2 gene with delirium, a meta-analysis

Delirium is the most common neuropsychiatric syndrome in elderly ill patients. Previously, associations between delirium and the dopamine transporter gene (solute carrier family 6, member 3 (SLC6A3)) and dopamine receptor 2 gene (DRD2) were found. The aim of this study was to validate whether markers of the SLC6A3 and DRD2 genes are were associated with delirium in independent populations. Six European populations collected DNA of older delirious patients. Associations were determined per population and results were combined in a meta-analysis. In total 820 medical inpatients, 185 cardiac surgery patients, 134 non-cardiac surgery patients and 502 population-based elderly subjects were included. Mean age was 82 years (SD 7.5 years), 598 (36%) were male, 665 (41%) had pre-existing cognitive impairment, and 558 (34%) experienced delirium. The SLC6A3 rs393795 homozygous AA genotype was more frequent in patients without delirium in all populations. The meta-analysis showed an Odds Ratio (OR) for delirium of 0.4 (95% confidence interval (C.I.) 0.2-0.6, P = 0.0003) for subjects with AA genotype compared to the AG and GG genotypes. SLC6A3 marker rs1042098 showed no association with delirium. In meta-analysis the DRD2 rs6276 homozygous GG genotype showed an OR of 0.8 for delirium (95% C.I. 0.6-1.1, P = 0.24). When subjects were stratified for cognitive status the rs6276 GG genotype showed ORs of 0.6 (95% C.I. 0.4-1.0, P = 0.06) and 0.8 (95% C.I. 0.5-1.5, P = 0.51) for delirium in patients with and without cognitive impairment, respectively. In independent cohorts, a variation in the SLC6A3 gene and possibly the DRD2 gene were found to protect for delirium.

Genetic polymorphisms in the DRD2, DRD3, and SLC6A3 gene in elderly patients with delirium

Dopamine excess appears to be critical in the final common pathway of delirium. The aim of this study was to investigate whether genetic polymorphisms in three dopamine-related genes (the dopamine receptor 2 (DRD2), dopamine receptor 3 (DRD3), and the dopamine transporter (SLC6A3) gene) were associated with delirium. Patients aged 65 years and older acutely admitted to the medical department or to the surgical department following hip fracture were included. Delirium was diagnosed by the Confusion Assessment Method. Sixteen single nucleotide polymorphisms (SNPs) and one variable number of tandem repeats in the SLC6A3 gene, nine SNPs in the DRD2 gene, and six SNPs in the DRD3 gene were genotyped. Fifty percent of the 115 surgical patients and 34% of the 605 medical patients experienced delirium. Delirious patients were older and had more frequently pre-existing functional and cognitive impairment (P < 0.001). After correction for multiple testing, one SNP in the SLC6A3 gene (rs393795) was associated with reduced risk of delirium (P = 0.032). Adjusted for age, cognitive impairment, and functional impairment, three SNPs in the DRD2 gene and seven SNPs in the SLC6A3 gene were associated with delirium; none of these associations was significant after correction for multiple testing. Variations in the SLC6A3 gene and possibly the DRD2 gene were associated with delirium. Although validation of these results is needed our results support a role for the dopamine transporter and dopamine receptor 2 in the pathogenesis of delirium.

The association between delirium and the apolipoprotein E epsilon 4 allele: new study results and a meta-analysis

OBJECTIVES

To determine a possible association between Apolipoprotein E (APOE)sigma4-allele and delirium in a large cohort and combining these current data with former studies in a meta-analysis.

DESIGN

Combination of a new prospective cohort study and meta-analysis.

SETTING

Medical department and orthopedic/traumatology department of University hospital from 2003 to 2007.

PARTICIPANTS

A total of 656 patients aged 65 years and older acutely admitted with a medical diagnosis or after hip fracture.

MEASUREMENTS

Confusion Assessment Method for delirium, Informant Questionnaire on Cognitive Decline-short form for predelirium global cognitive impairment, and Katz Index of Activities of Daily Living for functionality. APOE was genotyped by mass spectrometer. A meta-analysis was performed combining the current data with published studies analyzing the association between the APOE sigma4-allele and the delirium.

RESULTS

: The 49% of the 76 surgical patients and 35% of the 580 medical patients experienced delirium. Delirious patients were significantly older (82 versus 77 years) and had more frequently functional (66% versus 26%) and cognitive impairment (86% versus 29%) than nondelirious patients. The odds ratio (OR) for delirium adjusted for age, cognitive, and functional impairment of sigma4 carriers compared with non-sigma4 carriers was 1.7 (95% confidence interval [CI]: 1.1-2.6). Four studies were added to the meta-analysis, which included 1,099 patients in total. The OR for delirium in the meta-analysis was 1.6 (95% CI: 0.9-2.7) of sigma4 carriers compared with non-sigma4 carriers.

CONCLUSIONS

This study and meta-analysis suggest an association between delirium and the APOE sigma4 allele.

Challenges in phenotype definition in the whole-genome era: multivariate models of memory and intelligence

Refining phenotypes for the study of neuropsychiatric disorders is of paramount importance in neuroscience. Poor phenotype definition provides the greatest obstacle for making progress in disorders like schizophrenia, bipolar disorder, Attention Deficit/Hyperactivity Disorder (ADHD), and autism. Using freely available informatics tools developed by the Consortium for Neuropsychiatric Phenomics (CNP), we provide a framework for defining and refining latent constructs used in neuroscience research and then apply this strategy to review known genetic contributions to memory and intelligence in healthy individuals. This approach can help us begin to build multi-level phenotype models that express the interactions between constructs necessary to understand complex neuropsychiatric diseases. These results are available online through the http://www.phenowiki.org database. Further work needs to be done in order to provide consensus-building applications for the broadly defined constructs used in neuroscience research.

Evaluation and management of the elderly patient at risk for postoperative delirium

Geriatric patients are at a high risk for the development of postoperative delirium. By recognizing predisposing and precipitating risk factors, preventive measures can be undertaken to reduce this risk. Accurate and timely diagnosis is essential, and we offer therapeutic strategies to help reduce the high morbidity and mortality of this important condition.

The effects of apolipoprotein E on non-impaired cognitive functioning: a meta-analysis

Nearly twice as many participants are represented in the current literature than were available at the time of the last major meta-analytic neurocognitive examination of apolipoprotein E (ApoE) epsilon allele combinations [Small, B.J., Rosnick, C.B., Fratiglioni, L., Backman, L., 2004. Apolipoprotein E and cognitive performance: a meta-analysis. Psychol. Aging 19, 592-600]. The meta-analysis in the current study sought to specifically examine (1) small effects and (2) possible moderating variables associated with ApoE allele combinations that may have been undiscoverable in previous examinations of smaller data sets. A total of 77 studies, representing 40,942 cognitively healthy adults were identified for inclusion in the current meta-analysis (random effects design). Results were congruent with the previous meta-analytic findings indicating that carriers of ApoE allele 4 (ɛ4) perform significantly worse on measures of episodic memory, executive functioning, and overall global cognitive ability. In addition, the current analysis revealed a small effect suggesting that ApoE allele 4 adversely impacts perceptual speed. In contrast to earlier studies, the results also indicate that increases in age result in significantly larger differences between ApoE ɛ4 carriers and ApoE non-ɛ4 carriers on measures of episodic memory and global cognitive ability. ApoE ɛ4 exerts broad, but specific, adverse small effects on a range of neurocognitive functions in cognitively healthy adults.

The genetics of deliria

Delirium not induced by alcohol or other psychoactive substance and alcohol withdrawal delirium (or delirium tremens) are both cerebral syndromes with similar presentations and are associated with various adverse outcomes. Recently, interest in identifying genetic predisposing factors that influence the occurrence or the outcome of delirium has become a prominent point of delirium research. We systematically searched published articles concerning genetic associations and the occurrence and outcome of delirium. Of 33 identified articles, six investigated non-alcohol withdrawal delirium, and from those six, five evaluated an association with apolipoprotein E (APOE). One association of APOE genotype with the emergence of delirium and two associations of APOE genotype with the duration of delirium were reported. The remaining 27 identified articles investigated genetic associations with alcohol withdrawal delirium and were mainly related to dopamine. Two studies reported a significant association of alcohol withdrawal delirium with the dopamine transporter gene (SLC6A3) and the dopamine receptor 3 (DRD3). Results are inconclusive, and no hard evidence exists due primarily to insufficiently powered studies and other methodological issues. Prospective studies incorporating systematic and rigorous diagnostic criteria and involving long term follow up are needed to advance understanding of this field.

The role of SOAT-1 polymorphisms in cognitive decline and delirium after bypass heart surgery

BACKGROUND

Cognitive decline (CD) and delirium (PD) are commonly observed complications after bypass heart surgery. In this study we aimed to investigate whether certain genetic factors (alleles of the SOAT-1 gene) play a role in their appearance.

PATIENTS AND METHODS

We examined 137 patients receiving coronary bypass surgery with a neuropsychiatric test battery consisting of the Mini Mental State Examination (MMSE), the Brief Psychiatric Rating Scale (BPRS), the Wechsler's Memory Scale-Revised (WMS-R) on admission and one month after surgery, and the Delirium Rating Scale postoperatively, when indicated, and genotyped them in relation to the SOAT-1 genotypes (AA positive group with augmented protection of the nerve cells against stress and the AA negative group--AC and CC subgroups--with diminished protection against stress).

RESULTS

We noted a significant decline in test results postoperatively and a high frequency of delirium (29.92% of the patients). None of these complications could be associated to the SOAT-1 genotypes.

CONCLUSIONS

Our study confirmed the expected cognitive decline and highly frequent delirium after bypass heart surgery and excluded the possible role of SOAT-1 genotype polymorphisms in their genesis.