A systematic literature review of cerebrospinal fluid biomarkers in delirium

Biomarkers of delirium risk in older adults: a systematic review and meta-analysis

Delirium is a neuropsychiatric syndrome associated with increased morbidity and mortality in older patients. The aim of this study was to review predictive biomarkers of delirium in older patients to gain insights into the pathophysiology of this syndrome and provide guidance for future studies. Two authors independently and systematically searched MEDLINE, Embase, Cochrane Library, Web of Science and Scopus databases up to August 2021. A total of 32 studies were included. Only 6 studies were eligible for the meta-analysis, pooled results showed a significant increase in some serum biomarkers (C-reactive protein [CRP], tumour necrosis factor alpha [TNF-α] and interleukin-6 [IL-6]) among patients with delirium (odds ratio = 1.88, 95% CI 1.01 to 1.637; I2 = 76.75%). Although current evidence does not favour the use of any particular biomarker, serum CRP, TNF-α, and IL-6 were the most consistent biomarkers of delirium in older patients.

Postoperative delirium and changes in the blood-brain barrier, neuroinflammation, and cerebrospinal fluid lactate: a prospective cohort study

BACKGROUND

Case-control studies have associated delirium with blood-brain barrier (BBB) permeability. However, this approach cannot determine whether delirium is attributable to high pre-existing permeability or to perioperative changes. We tested whether perioperative changes in cerebrospinal fluid/plasma albumin ratio (CPAR) and plasma S100B were associated with delirium severity.

METHODS

Participants were recruited to two prospective cohort studies of non-intracranial surgery (NCT01980511, NCT03124303, and NCT02926417). Delirium severity was assessed using the Delirium Rating Scale-98. Delirium incidence was diagnosed with the 3D-Confusion Assessment Method (3D-CAM) or CAM-ICU (CAM for the ICU). CSF samples from 25 patients and plasma from 78 patients were analysed for albumin and S100B. We tested associations between change in CPAR (n=11) and S100B (n=61) and delirium, blood loss, CSF interleukin-6 (IL-6), and CSF lactate.

RESULTS

The perioperative increase in CPAR and S100B correlated with delirium severity (CPAR ρ=0.78, P=0.01; S100B ρ=0.41, P<0.001), delirium incidence (CPAR P=0.012; S100B P<0.001) and CSF IL-6 (CPAR ρ=0.66 P=0.04; S100B ρ=0.75, P=0.025). Linear mixed-effect analysis also showed that decreased levels of S100B predicted recovery from delirium symptoms (P=0.001). Linear regression demonstrated that change in plasma S100B was independently associated with surgical risk, cardiovascular surgery, blood loss, and hypotension. Blood loss also correlated with CPAR (ρ=0.64, P=0.04), S100B (ρ=0.70, P<0.001), CSF lactate (R=0.81, P=0.01), and peak delirium severity (ρ=0.36, P=0.01).

CONCLUSION

Postoperative delirium is associated with a breakdown in the BBB. This increased permeability is dynamic and associated with a neuroinflammatory and lactate response. Strategies to mitigate blood loss may protect the BBB.

Delirium and long term cognition in critically ill patients

Delirium, a form of acute brain dysfunction, is very common in the critically ill adult patient population. Although its pathophysiology is poorly understood, multiple factors associated with delirium have been identified, many of which are coincident with critical illness. To date, no drug or non-drug treatments have been shown to improve outcomes in patients with delirium. Clinical trials have provided a limited understanding of the contributions of multiple triggers and processes of intensive care unit (ICU) acquired delirium, making identification of therapies difficult. Delirium is independently associated with poor long term outcomes, including persistent cognitive impairment. A longer duration of delirium is associated with worse long term cognition after adjustment for age, education, pre-existing cognitive function, severity of illness, and exposure to sedatives. Interestingly, differences in prevalence are seen between ICU survivor populations, with survivors of acute respiratory distress syndrome experiencing higher rates of cognitive impairment at early follow-up compared with mixed ICU survivor populations. Although cognitive performance improves over time for some ICU survivors, impairment is persistent in others. Studies have so far been unable to identify patients at higher risk of long term cognitive impairment; this is an active area of scientific investigation.

Elevated Monocyte Chemoattractant Protein-1 as the Independent Risk Factor of Delirium after Cardiac Surgery. A Prospective Cohort Study

BACKGROUND

The pathogenesis of postoperative delirium is largely unknown. The primary objective of this study is to assess whether increased levels of monocyte chemoattractant protein-1 (MCP-1) and high-sensitivity C-reactive protein (hsCRP) are associated with postoperative delirium in patients who have undergone cardiac surgery. The secondary objective is to investigate whether any association between raised inflammatory biomarkers levels and delirium is related to surgical and anesthetic procedures or mediated by pre-existing psychiatric conditions associated with raised pro-inflammatory markers levels.

METHODS

The patients were screened for cognitive impairment one day preoperatively with the use of the Mini-Mental State Examination Test and the Clock Drawing Test. A diagnosis of major depressive disorder (MDD) and anxiety disorders was established on the basis of Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria. Blood samples were collected pre- and postoperatively for hsCRP and chemokine levels.

RESULTS

Postoperative delirium developed in 34% (61 of 177) of patients. Both pre- and postoperative hsCRP, and preoperative MCP-1 levels were associated with postoperative delirium in univariate comparisons; p = 0.001; p < 0.001; p < 0.001, respectively. However, according to a multivariable logistic regression analysis, only a raised MCP-1 concentration before surgery was independently associated with postoperative delirium, and related to advancing age, preoperative anxiety disorders and prolonged intubation.

CONCLUSIONS

The present study suggests that an elevated preoperative MCP-1 concentration is associated with delirium after cardiac surgery. Monitoring of this inflammatory marker may reveal the cardiovascular disease (CVD) patients who are at risk of neuropsychiatric syndromes development.

Challenges of Delirium Management in Patients with Traumatic Brain Injury: From Pathophysiology to Clinical Practice

Traumatic brain injury (TBI) can initiate a very complex disease of the central nervous system (CNS), starting with the primary pathology of the inciting trauma and subsequent inflammatory and CNS tissue response. Delirium has long been regarded as an almost inevitable consequence of moderate to severe TBI, but more recently has been recognized as an organ dysfunction syndrome with potentially mitigating interventions. The diagnosis of delirium is independently associated with prolonged hospitalization, increased mortality and worse cognitive outcome across critically ill populations. Investigation of the unique problems and management challenges of TBI patients is needed to reduce the burden of delirium in this population. In this narrative review, possible etiologic mechanisms behind post-traumatic delirium are discussed, including primary injury to structures mediating arousal and attention and secondary injury due to progressive inflammatory destruction of the brain parenchyma. Other potential etiologic contributors include dysregulation of neurotransmission due to intravenous sedatives, seizures, organ failure, sleep cycle disruption or other delirium risk factors. Delirium screening can be accomplished in TBI patients and the presence of delirium portends worse outcomes. There is evidence that multi-component care bundles including an analgesia-prioritized sedation algorithm, regular spontaneous awakening and breathing trials, protocolized delirium assessment, early mobility and family engagement can reduce the burden of ICU delirium. The aim of this review is to summarize the approach to delirium in TBI patients with an emphasis on pathogenesis and management. Emerging CNS-active drug therapies that show promise in preclinical studies are highlighted.

Age, preoperative higher serum cortisol levels, and lower serum acetylcholine levels predict delirium after percutaneous coronary intervention in acute coronary syndrome patients accompanied with renal dysfunction

BACKGROUND

The objective of the study is to investigate the incidence and risk factors of delirium after percutaneous coronary intervention (PCI) in acute coronary syndrome (ACS) patients accompanied with renal dysfunction.

MATERIALS AND METHODS

This was a prospective and cohort study, performed in a medical center from July 2014 to June 2017, which enrolled ACS patients accompanied with renal dysfunction who were treated with PCI. Univariate analysis and binary logistic regression analysis was used to determine the incidence and risk factors of delirium.

RESULTS

Data were analyzed from 119 patients. The 7-day incidence of delirium after PCI in ACS patients accompanied with renal dysfunction was 15.97% (n = 19/119). The binary logistic regression analysis results indicate that age (odd ratio [OR] 1.463; 95% confidence interval [CI] 1.070-2.001; P = 0.017), preoperative higher serum cortisol (COR) (OR 1.025; 95% CI 1.002-1.048; P = 0.030), and lower serum acetylcholine (Ach) (OR 0.965; 95% CI 0.937-0.993; P = 0.016) were significant differences in delirium and nondelirium groups.

CONCLUSIONS

Age, preoperative higher serum COR levels, and lower serum Ach levels were independent risk factors for delirium after PCI in ACS patients accompanied with renal dysfunction.

Use of statins and the risk of delirium in critically ill and surgical patients: Protocol of a systematic review and meta-analysis

BACKGROUND

The critically ill and surgical patients are at significant risk of delirium, which is associated with a high morbidity and mortality. The association between statin use and the incidence of delirium is still controversial. In this article, we will perform a systematic review and meta-analysis of published studies to evaluate the effectiveness of statins for the prophylaxis of delirium among critically ill and surgical patients.

METHODS

We will conduct a systematic literature search in EMBASE, PubMed, and the Cochrane Library from inception date to October 2018 for randomized controlled trials (RCTs) and observational studies (either cohort or case-control studies) investigating the association between use of statins and delirium risk. The Cochrane Collaboration's tool for evaluating the risk of bias and Newcastle-Ottawa scale (NOS) will be used to assess the methodological quality of RCTs and observational studies, separately. The primary outcome will be the risk of incident delirium associated with statin use. Pooled odds ratios (ORs) with corresponding 95% confidence intervals (CIs) will be calculated by a random-effects or fixed-effects model according to heterogeneity among included studies. Subgroup analyses, meta-regression method, and assessment of publication bias will be also performed. Statistical analyses will be conducted with RevMan (version 5.3.5) and Stata (version 14.0) software. In addition, the grading of recommendations assessment, development and evaluation (GRADE) approach will be applied to evaluate the quality of evidence.

RESULTS

The study will provide a high-quality synthesis and evaluate the effectiveness of statins for delirium prevention among critically ill and surgical patients.

CONCLUSIONS

The systematic review and meta-analysis will provide convincing evidence concerning the effect of statins against delirium in critically ill and surgical patients.

CSF biomarkers in delirium: a systematic review

OBJECTIVE

In recent years, there has been a blossoming of studies examining cerebrospinal fluid (CSF) as a method of studying the pathophysiology of delirium. We systematically reviewed the literature for CSF studies in delirium and provide here a summary of the implications for our understanding of delirium pathophysiology. We also summarise the methods used for CSF analysis and discuss challenges and implications for future studies.

METHODS

In this systematic review, we screened MEDLINE, EMBASE, PsycINFO, Web of Science, PubMed and the Cochrane Library for articles on CSF biomarkers in delirium, published on 3 September 2016. Studies were required to use Diagnostic and Statistical Manual of Mental Disorders or International Classification of Diseases criteria for delirium or a validated tool. We excluded case reports. There were no other restrictions on study type.

RESULTS

We identified 3280 articles from our initial search, and 22 articles were included in this review. All studies were prospective, including over 400 patients with delirium and 700 controls. More than 70 different biomarkers were studied. Studies could not be compared with each other for meta-analysis because of their heterogeneity and varied widely in their risk of bias and quality assessments.

CONCLUSIONS

The 22 studies identified in this review reveal a small but growing literature, in which many of the important hypotheses in delirium pathogenesis have been examined, but from which few firm conclusions can currently be drawn. Nevertheless, the overall interpretation of the literature supports the vulnerable brain concept, that is, that biomarker evidence of, for example, Alzheimer's disease pathology and/or neuroinflammation, is associated with delirium.

Acetylcholinesterase Activity Measurement and Clinical Features of Delirium

AIMS

Cholinergic deficiency is commonly implicated in the pathophysiology of delirium. We aimed to investigate the relationship between directly measured serum acetylcholinesterase (AChE) activity and (1) clinical features of delirium and (2) outcomes among older hospital patients with delirium.

METHODS

Hospitalised patients with delirium were recruited, and delirium motor subtype, severity and duration of delirium were measured. Serum AChE activity was measured using a colorimetric assay.

RESULTS

The mean AChE activity for the whole sample was 2.46 μmol/μL/min (standard deviation 1.75). Higher AChE activity was associated with increased likelihood of hypoactive delirium rather than the hyperactive or mixed subtype (odds ratio 1.98, 95% confidence interval 1.10-3.59).

CONCLUSION

Higher AChE activity was associated with hypoactive delirium but did not predict outcomes. Simple enhancement of cholinergic neurotransmission may not be sufficient to treat delirium.

Pathophysiological and behavioral effects of systemic inflammation in aged and diseased rodents with relevance to delirium: A systematic review

Delirium is a frequent outcome for aged and demented patients that suffer a systemic inflammatory insult. Animal models that reconstruct these etiological processes have potential to provide a better understanding of the pathophysiology of delirium. Therefore, we systematically reviewed animal studies in which systemic inflammation was superimposed on aged or diseased animal models. In total, 77 studies were identified. Aged animals were challenged with a bacterial endotoxin in 29 studies, 25 studies superimposed surgery on aged animals, and in 6 studies a bacterial infection, Escherichia coli (E. coli), was used. Diseased animals were challenged with a bacterial endotoxin in 15 studies, two studies examined effects of the cytokine IL-1β, and one study used polyinosinic:polycytidilic acid (poly I:C). This systematic review analyzed the impact of systemic inflammation on the production of inflammatory and neurotoxic mediators in peripheral blood, cerebrospinal fluid (CSF), and on the central nervous system (CNS). Moreover, concomitant behavioral and cognitive symptoms were also evaluated. Finally, outcomes of behavioral and cognitive tests from animal studies were compared to features and symptoms present in delirious patients.

Lack of Association between Preoperative Statin Use and Respiratory and Neurologic Complications after Cardiac Surgery

Background

Statins may reduce the risk of pulmonary and neurologic complications after cardiac surgery.

Methods

The authors acquired data for adults who had coronary artery bypass graft, valve surgery, or combined procedures. The authors matched patients who took statins preoperatively to patients who did not. First, the authors assessed the association between preoperative statin use and the primary outcomes of prolonged ventilation (more than 24 h), pneumonia (positive cultures of sputum, transtracheal fluid, bronchial washings, and/or clinical findings consistent with the diagnosis of pneumonia), and in-hospital all-cause mortality, using logistic regressions. Second, the authors analyzed the collapsed composite of neurologic complications using logistic regression. Intensive care unit and hospital length of stay were evaluated with Cox proportional hazard models.

Results

Among 14,129 eligible patients, 6,642 patients were successfully matched. There was no significant association between preoperative statin use and prolonged ventilation (statin: 408/3,321 [12.3%] vs. nonstatin: 389/3,321 [11.7%]), pneumonia (44/3,321 [1.3%] vs. 54/3,321 [1.6%]), and in-hospital mortality (52/3,321 [1.6%] vs. 43/3,321 [1.3%]). The estimated odds ratio was 1.06 (98.3% CI, 0.88 to 1.27) for prolonged ventilation, 0.81 (0.50 to 1.32) for pneumonia, and 1.21 (0.74 to 1.99) for in-hospital mortality. Neurologic outcomes were not associated with preoperative statin use (53/3,321 [1.6%] vs. 56/3,321 [1.7%]), with an odds ratio of 0.95 (0.60 to 1.50). The length of intensive care unit and hospital stay was also not associated with preoperative statin use, with a hazard ratio of 1.04 (0.98 to 1.10) for length of hospital stay and 1.00 (0.94 to 1.06) for length of intensive care unit stay.

Conclusions

Preoperative statin use did not reduce pulmonary or neurologic complications after cardiac surgery.

Serum levels of neuron-specific enolase in patients with fibromyalgia syndrome: Correlation with cognitive functions, quality of life and psychological state

BACKGROUND

Fibromyalgia syndrome (FMS) is a non-articular rheumatic disorder of unclear etiology, characterized by widespread body pain, fatigue and, psychological complaintsOBJECTIVES: To investigate the serum levels of neuron-specific enolase (NSE) in patients with FMS and to evaluate the relationship between cognitive function, quality of life and psychological state.

MATERIALS AND METHODS

Fifty-five female patients diagnosed with fibromyalgia according to the American College of Rheumatology (ACR) classification criteria, and 40 healthy female subjects were enrolled in the study. Life quality scale [(Fibromyalgia Impact Questionnaire (FIQ)], psychological state (Beck Depression Scale), and cognitive dysfunction (mini mental test, clock drawing test) scales were used for patients and control subjects. Serum NSE levels were studied using the ECLIA method.

RESULTS

No significant differences were found in the serum NSE levels between the FMS patients and the control subjects (p> 0.05). Life quality and psychological state scores were found to be higher in FMS patients relative to the control group (p< 0.001). However, no significant differences were detected in cognitive function (p> 0.05). Significant correlations were not found between the serum NSE levels and quality of life, psychological state and cognitive functions (p> 0.05).

CONCLUSION

No significant difference was determined between the groups in terms of NSE levels. Further studies, including larger series, should be carried out to clarify this relationship.

5-HT(1A) receptor antagonist improves behavior performance of delirium rats through inhibiting PI3K/Akt/mTOR activation-induced NLRP3 activity

Postoperative delirium is a common complication that often results in poor outcomes in surgical and elderly patients. Accumulating evidences suggest that the pathophysiology of delirium results from multiple neurotransmitter system dysfunctions. To further clarify the effects of the selective serotonin (5-HT) (1A) antagonist WAY-100635 on the behaviors in scopolamine induced-delirium rats and to explore the molecular mechanism, in this study, we investigated the change of monoamine levels in the cerebrospinal fluid (CSF) and different brain regions using high-performance liquid chromatography and assessed the behavioral retrieval of delirium rats treated with WAY-100635. It was found that 5-hydroxy-3-indoleacetic acid (5-HIAA), 3,4-dihydroxyphenylacetic acid, and homovanillic acid concentrations in the CSF of scopolamine-induced delirium rats were significantly increased, among which 5-HIAA was also increased in hippocampus and basolateral amygdala (BLA), and 5-HT(1A) receptor was significantly higher in the hippocampuses and BLA than other brain regions. Furthermore, intrahippocampus and intra-BLA stereotactic injection of WAY-100635 improved the delirium-like behavior of rats. Mechanistically, after WAY-100635 treatment, significant reduction of IL-1β release into CSF and NOD-like receptor family, pyrin domain containing 3 (NLRP3) expression, phosphorylated phosphatidylinositol-3-kinase (PI3K), protein kinase B (AKT), and S6K was observed. Altogether, these results suggest that delirium rats induced by scopolamine may be correlated with an increased cerebral concentration of 5-HT and dopamine neurotransmitters system; the selective 5-HT(1A) antagoniszts can reverse the delirium symptoms at some extent through tendering PI3K/Akt/mammalian target of rapamycin complex 1 (mTOR) activation-induced NLRP3 activity and then reducing IL-1β release.

Preoperative protein profiles in cerebrospinal fluid in elderly hip fracture patients at risk for delirium: A proteomics and validation study

BACKGROUND

A neuroinflammatory response is suggested to play an important role in delirium, a common complication in older hospitalized patients. We examined whether hip fracture patients who develop postoperative delirium have a different proteome in cerebrospinal fluid (CSF) prior to surgery.

METHODS

Patients (≥ 75 years) were admitted for hip fracture surgery. CSF was collected during spinal anaesthesia; proteins were separated using gel electrophoresis and identified with mass spectrometry. We compared the proteome of patients with and without postoperative delirium. Findings were validated in an independent, comparable cohort using immuno-assays.

RESULTS

In the derivation cohort 53 patients were included, 35.8% developed postoperative delirium. We identified differences in levels of eight CSF proteins between patients with and without subsequent delirium: complement factor C3, contactin-1, fibulin-1 and I-beta-1,3-N-acetylglucosaminyltransferase were significantly lower in patients with postoperative delirium, while neural cell adhesion molecule-2, fibrinogen, zinc-α-2-glycoprotein and haptoglobin levels were significantly higher. In the validation cohort 21.2% of 52 patients developed postoperative delirium. Immuno-assays confirmed contactin-1 results although not statistically significant. Complement factor C3 was significantly higher in patients with postoperative delirium.

CONCLUSION

Our results show the complexity of pathophysiological mechanisms involved in delirium and emphasizes the need of independent validation of findings.

GENERAL SIGNIFICANCE

This study highlights the challenges and inconsistent findings in studies of delirium, a serious complication in older patients. We analysed proteins in CSF, the most proximal fluid to the brain. All patients were free from delirium at the time of sampling.

Mild cognitive impairment with associated inflammatory and cortisol alterations as independent risk factor for postoperative delirium

AIMS

The present study aimed to determine the impact of mild cognitive impairment (MCI) on the development of postoperative delirium and, secondly, to assess the association between MCI and raised perioperative cortisol, cytokine, cobalamin and homocysteine levels.

METHODS

The study recruited 113 consecutive adult patients scheduled for cardiac surgery with cardiopulmonary bypass. The patients were examined preoperatively with the Montreal Cognitive Assessment and Trail Making Test. A diagnosis of MCI was established based upon the criteria of the National Institute on Aging and Alzheimer's Association. Patients were screened for delirium within the first 5 days postoperatively.

RESULTS

MCI was diagnosed in 24.8% of the patients, whereas the frequency of delirium was 36%. A multivariate analysis demonstrated that individuals with MCI were at a significantly higher risk of postoperative delirium (OR = 6.33, p = 0.002). Preoperative cortisol, postoperative cortisol and IL-2 plasma levels were higher in the MCI group as compared to non-MCI subjects.

CONCLUSION

MCI is associated with a higher risk of postoperative delirium. Perioperative cortisol and inflammatory alterations observed in MCI may provide a physiological explanation for this increased risk.

Enzyme-specific sensors via aggregation of charged p-phenylene ethynylenes

Chemical and biological sensors are sought for their ability to detect enzymes as biomarkers for symptoms of various disorders, or the presence of chemical pollutants or poisons. p-Phenylene ethynylene oligomers with pendant charged groups have been recently shown to have ideal photophysical properties for sensing. In this study, one anionic and one cationic oligomer are combined with substrates that are susceptible to enzymatic degradation by phospholipases or acetylcholinesterases. The photophysical properties of the J-aggregated oligomers with the substrate are ideal for sensing, with fluorescence quantum yields of the sensors enhanced between 30 and 66 times compared to the oligomers without substrate. The phospholipase sensor was used to monitor the activity of phospholipase A1 and A2 and obtain kinetic information, though phospholipase C did not degrade the sensor. The acetylcholinesterase sensor was used to monitor enzyme activity and was also used to detect the inhibition of acetylcholinesterase by three different inhibitors. Phospholipase A2 is a biomarker for heart and circulatory disease, and acetylcholinesterase is a biomarker for Alzheimer's, and indicative of exposure to certain pesticides and nerve agents. This work shows that phenylene ethynylene oligomers can be tailored to enzyme-specific sensors by careful selection of substrates that induce formation of a molecular aggregate, and that the sensing of enzymes can be extended to enzyme kinetics and detection of inhibition. Furthermore, the aggregates were studied through all-atom molecular dynamics, providing a molecular-level view of the formation of the molecular aggregates and their structure.

Diagnostic and treatment practices of delirium in a general hospital

BACKGROUND

Despite the increase in research on delirium, it remains underdiagnosed and difficult to manage, and the outcome is poor especially in older people.

AIMS

To identify the clinically diagnosed rates of delirium, the possible aetiologies, to describe treatment, number and type of psychotropic medication used and to investigate the reasons for referral to a liaison psychiatric team.

METHODS

Retrospective study of medical records of inpatients admitted to Sligo Regional Hospital during an 18-month period.

RESULTS

One hundred and fifty-six files had a documentation of delirium (time prevalence 2%). Mean age of the sample was 82 years (SD = 7.2), 66 (42%) were male. Sixty-nine (44.2%) of the total sample had a previous history of dementia, and 57 (36.5%) had a previous history of delirium. In 67 (43.2%) samples, the cause was infection, while in 4, no specific cause was identified. Ninety (58%) were referred to the liaison service, but only in 26 (28.9 %), the reason for referral was "acute confusion" or "delirium". In a majority of referrals, the reason was an affective disorder more often depression. There were no significant differences between delirium subtypes and referrals (χ(2) = 3.868, df 3, p = 0.28). Examination of the amount of antipsychotics prescribed before, during and after delirium shows that there was a significant increase in use during the delirium (χ(2) = 17.512, df 8, p = 0.025) and decrease in z-hypnotics medication (zopiclone/zolpidem), (χ(2) = 20.114, df 4, p < 0.001), while benzodiazepines and antidepressants remained the same.

CONCLUSIONS

Delirium is often misdiagnosed and unrecognized in hospital settings; however, when identified the pharmacological management is appropriate.

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.

Raised IL-2 and TNF-α concentrations are associated with postoperative delirium in patients undergoing coronary-artery bypass graft surgery

BACKGROUND

The knowledge base regarding the pathogenesis of postoperative delirium is limited. The primary aim of this study is to investigate whether increased levels of IL-2 and TNF-α are associated with delirium in patients who underwent coronary-artery bypass graft (CABG) surgery with cardiopulmonary bypass (CPB). The secondary aim is to establish whether any association between raised cytokine levels and delirium is related to surgical and anesthetic procedures or mediated by pre-existing conditions associated with raised cytokine levels, such as major depressive disorder (MDD), cognitive impairment, or aging.

METHODS

Patients were examined and screened for MDD and cognitive impairment one day preoperatively, using the Mini International Neuropsychiatric Interview and The Montreal Cognitive Assessment and Trail Making Test Part B. Blood samples were collected postoperatively for cytokine levels.

RESULTS

Postoperative delirium screening was found positive in 36% (41 of 113) of patients. A multivariate logistic regression revealed that an increased concentration of pro-inflammatory cytokines is associated with delirium, and related to advancing age, preoperative cognitive decline of participants, and duration of CPB. According to receiver operating characteristic analysis, the most optimal cut-off for IL-2 and TNF-α concentrations in predicting the development of delirium were 907.5 U/ml and 10.95 pg/ml, respectively.

CONCLUSIONS

The present study suggests that raised postoperative cytokine concentrations are associated with delirium after CABG surgery. Postoperative monitoring of pro-inflammatory markers combined with regular surveillance may be helpful in the early detection of postoperative delirium in this patient group.

AAI-guided anaesthesia is associated with lower incidence of 24-h MMSE < 25 and may impact the IL-6 response

INTRODUCTION

Trauma stress and neuro-inflammation caused by surgery/anaesthesia releases cytokines. This study analysed impact of Auditory Evoked Potential Index (AAI) depth-of-anaesthesia titration on the early plasma IL-6 release after eye surgery under general anaesthesia.

METHOD

This is a subgroup analysis of a prospective randomized study on the effect of auditory evoked potential guided anaesthesia for eye surgery. Plasma IL-6 levels taken before, 5 and 24 h after end of surgery from 450 patients undergoing elective ophthalmic surgery under desflurane anaesthesia were analysed. Minimal mental state examination (MMSE) was also tested at 24-h.

RESULTS

IL- 6 increased significantly at both 5 and further at 24 h after surgery (3.2, 4.5 and 5.1 base-line, 5 and 24-h respectively), the IL-6 increase showed different patterns between the 2 groups; IL-6 was significantly increased in the control group of patients between preoperative baseline and 24 h after surgery (p = 0.008) also between 5 h and 24 h, (p = 0.006) after surgery while the AAI-group had only minor non-significant changes. The 18 patients that showed a 24-h MMSE score less than 25 had a significant higher 24-h IL-6 compared to the 390 patients with a MMSE score > 24 (p = 0.002).

CONCLUSION

The IL-6 increase after surgery was less pronounced in patients where anaesthesia was titrated by AAI compared to anaesthesia adjusted on clinical signs only. IL-6 were also found to be higher in patients with a MMSE < 25 at 24-h. Further studies are warranted evaluating the role of depth of anaesthesia monitoring on the risk for early cognitive impairment and neuro-inflammation.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NA/study were conducted between January 2005-April 2008.

Improving delirium care through early intervention: from bench to bedside to boardroom

Delirium is a complex neuropsychiatric syndrome that impacts adversely upon patient outcomes and healthcare outcomes. Delirium occurs in approximately one in five hospitalised patients and is especially common in the elderly and patients who are highly morbid and/or have pre-existing cognitive impairment. However, efforts to improve management of delirium are hindered by gaps in our knowledge and issues that reflect a disparity between existing knowledge and real-world practice. This review focuses on evidence that can assist in prevention, earlier detection and more timely and effective pharmacological and non-pharmacological management of emergent cases and their aftermath. It points towards a new approach to delirium care, encompassing laboratory and clinical aspects and health services realignment supported by health managers prioritising delirium on the healthcare change agenda. Key areas for future research and service organisation are outlined in a plan for improved delirium care across the range of healthcare settings and patient populations in which it occurs.

The immunology of delirium

Delirium is an acute neuropsychiatric syndrome characterized by acute-onset global cognitive deficits, perceptual and behavioural disturbances affecting mainly elderly subjects with underlying medical or surgical conditions. The pathophysiology of delirium is complex and inflammation is a relevant precipitant factor of this syndrome, although it remains unclear how acute systemic inflammation induces the clinical picture of delirium. The central nervous system is able to detect peripheral infection or tissue destruction through circulating immune mediators and neural ascending signs. Activated microglia is responsible for an acute neuroinflammatory reaction underlying the symptoms of sickness. In healthy conditions descending pathways from the paraventricular nucleus, locus coeruleus and dorsal motor nucleus organize a centralized response to influence the immune response at the periphery and restore homeostasis. In the context of ageing and chronic neurodegeneration, adaptive changes to acute insults are characterized by exaggerated production of pro-inflammatory cytokines by primed microglia coupled with dysfunction of brain-to-immune pathways. In animal models, these changes underlie a more severe manifestation of sickness behaviour with working memory deficits suggesting that inattention, a core feature of delirium, can be a clinical correlate of an increased neuroinflammatory reaction. In patients with delirium, higher levels of pro-inflammatory cytokines and cortisol were identified in plasma and cerebrospinal fluid. However, to date it has not been clarified how peripheral inflammatory or endocrine biomarkers can reflect the likelihood or severity of delirium symptoms. In the future, a better understanding of the interaction between the brain and peripheral organs and the exact mechanism by which systemic inflammation can lead to delirium, will allow the development of new therapeutic agents.

Do stress markers and anesthetic technique predict delirium in the elderly?

BACKGROUND

Postoperative delirium (PD) is a prevalent complication of elderly surgical patients, which predisposes to worsened cognitive recovery and dementia. Risk of PD has been associated with increasing magnitude of the hypothalamic-pituitary-adrenal stress response (serum cortisol, epinephrine and norepinephrine) to surgery. Anesthetics suppress this response; however, some (total intravenous anesthesia, TIVA) more than others (anesthetic gases). Prior comparisons of anesthetics have been equivocal but have not included stress markers. We hypothesized that TIVA would decrease serum stress markers and the incidence of PD.

METHODS

We performed a prospective cohort study of 76 elderly major surgical patients. Patients received TIVA or sevoflurane gas, and blood was drawn for serum markers pre-, intra-, and postoperatively. PD was assessed with the Confusion Assessment Method. We compared stress markers and PD between patients who received TIVA versus sevoflurane, and then modeled PD including stress and anesthetic.

RESULTS

The group that received TIVA during surgery demonstrated lower levels of all stress markers compared to the gas group, but no difference in PD. However, across groups, the postoperative norepinephrine level was much higher in patients who developed PD. Other markers and other times had no effect.

CONCLUSION

The development of PD depends more on postoperative stress than intraoperative stress or anesthetic.

The epidemiology of delirium: challenges and opportunities for population studies

Delirium is a serious and common acute neuropsychiatric syndrome that is associated with short- and long-term adverse health outcomes. However, relatively little delirium research has been conducted in unselected populations. Epidemiologic research in such populations has the potential to resolve several questions of clinical significance in delirium. Part 1 of this article explores the importance of population selection, case-ascertainment, attrition, and confounding. Part 2 examines a specific question in delirium epidemiology: What is the relationship between delirium and trajectories of cognitive decline? This section assesses previous work through two systematic reviews and proposes a design for investigating delirium in the context of longitudinal cohort studies. Such a design requires robust links between community and hospital settings. Practical considerations for case-ascertainment in the hospital, as well as the necessary quality control of these programs, are outlined. We argue that attention to these factors is important if delirium research is to benefit fully from a population perspective.

Delirium and cerebrospinal fluid S100B in hip fracture patients: a preliminary study

OBJECTIVES

Delirium is associated with an increased risk of long-term cognitive decline, suggesting the possibility of concurrent central nervous system (CNS) injury. S100B is a putative biomarker of CNS injury and elevated serum levels in delirium have been reported. Here we hypothesize that delirium is associated with raised concentrations of cerebrospinal fluid (CSF) S100B.

METHODS

Forty-five patients with hip fracture aged over 60 and awaiting surgery under spinal anesthesia were assessed for delirium pre- and post-operatively. CSF S100B levels were measured in samples collected at the onset of surgery.

RESULTS

Participants with pre-operative delirium (N = 8) had elevated Log10 CSF S100B (mean: -0.156; SD: 0.238) compared with those without delirium (mean: -0.306; SD: 0.162), Student's t-test t = 2.18, df = 43, p = 0.035.

CONCLUSIONS

This study provides preliminary evidence of elevated CSF S100B in current delirium, consistent with findings in serum and with other studies showing elevated S100B in the presence of diverse forms of CNS injury.

New horizons in the pathogenesis, assessment and management of delirium

Delirium is one of the foremost unmet medical needs in healthcare. It affects one in eight hospitalised patients and is associated with multiple adverse outcomes including increased length of stay, new institutionalisation, and considerable patient distress. Recent studies also show that delirium strongly predicts future new-onset dementia, as well as accelerating existing dementia. The importance of delirium is now increasingly being recognised, with a growing research base, new professional international organisations, increased interest from policymakers, and greater prominence of delirium in educational and audit programmes. Nevertheless, the field faces several complex research and clinical challenges. In this article we focus on selected areas of recent progress and/or uncertainty in delirium research and practice. (i) Pathogenesis: recent studies in animal models using peripheral inflammatory stimuli have begun to suggest mechanisms underlying the delirium syndrome as well as its link with dementia. A growing body of blood and cerebrospinal fluid studies in humans have implicated inflammatory and stress mediators. (ii) Prevention: delirium prevention is effective in the context of research studies, but there are several unresolved issues, including what components should be included, the role of prophylactic drugs, and the overlap with general best care for hospitalised older people. (iii) Assessment: though there are several instruments for delirium screening and assessment, detection rates remain dismal. There are no clear solutions but routine screening embedded into clinical practice, and the development of new rapid screening instruments, offer potential. (iv) Management: studies are difficult given the heterogeneity of delirium and currently expert and comprehensive clinical care remains the main recommendation. Future studies may address the role of drugs for specific elements of delirium. In summary, though facing many challenges, the field continues to make progress, with several promising lines of enquiry and an expanding base of interest among researchers, clinicians and policymakers.

Bupropion pre-treatment of endotoxin-induced depressive symptoms

Increased levels of inflammatory cytokines may play a role in depression. Depressive symptoms can be induced in humans with administration of low-dose lipopolysaccharide (LPS; endotoxin), which activates the innate immune system and causes release of inflammatory cytokines. We previously found that pre-treatment with the serotonin reuptake inhibitor citalopram reduced LPS-induced fatigue and anhedonia. This is a follow-up study to determine whether LPS-induced symptoms could be reduced by pre-treatment with bupropion, a norepinephrine and dopamine reuptake inhibitor. In this double-blind, randomized, placebo-controlled, cross-over study, 10 healthy subjects received intravenous LPS (0.8 ng/kg) after oral pre-treatment with bupropion (75 mg twice a day) or placebo for 7 days. The Montgomery-Åsberg Depression Rating Scale (MADRS), the Profile of Mood States (POMS), and a visual analog scale (VAS) were used to measure depressive symptoms. Serum levels of inflammatory cytokines and chemokines were measured with electrochemiluminescence assays. The results of this study, which must be considered preliminary, showed that LPS administration was associated with (1) increase in serum levels of all cytokines and chemokines assayed; (2) increase in total MADRS score, mostly due to items 7 (lassitude) and 8 (anhedonia); (3) increase in fatigue; (4) decrease in vigor; and (5) decrease in social interest. Bupropion pre-treatment had no statistically significant effect on the innate immune response to LPS or on LPS-induced behavioral changes, suggesting that 1-week pre-treatment with bupropion does not inhibit LPS-induced fatigue and anhedonia, contrary to what was found previously with citalopram.

Perioperative delirium and its relationship to dementia

A number of serious clinical cognitive syndromes occur following surgery and anesthesia. Postoperative delirium is a behavioral syndrome that occurs in the perioperative period. It is diagnosed through observation and characterized by a fluctuating loss of orientation and confusion. A distinct syndrome that requires formalized neurocognitive testing is frequently referred to as postoperative cognitive dysfunction (POCD). There are serious concerns as to whether either postoperative delirium or postoperative cognitive dysfunction leads to dementia. These concerns are reviewed in this article.

Cytokines: how important are they in mediating sickness?

Sickness refers to a set of coordinated physiological and behavioral changes in response to systemic inflammation. It is characterized by fever, malaise, social withdrawal, fatigue, and anorexia. While these responses collectively represent a protective mechanism against infection and injury, increasing lines of evidence indicate that over-exaggerated or persistent sickness can damage the brain, and could possibly raise the risk to developing delirium. Therefore, a clear understanding in sickness will be beneficial. It has long been believed that sickness results from increased systemic cytokines occurring during systemic inflammation. However, in recent years more and more conflicting data have suggested that development of sickness following peripheral immune challenge could be independent of cytokines. Hence, it is confusing as to whether cytokines really do act as primary mediators of sickness, or if they are secondary to alternative inducing factor(s). In this review, we will (1) introduce the relationships between systemic inflammation, cytokines, sickness, and delirium, and (2) attempt to interpret the recent controversies.

Delirium in hospitalized patients: implications of current evidence on clinical practice and future avenues for research--a systematic evidence review

BACKGROUND

Despite the significant burden of delirium among hospitalized adults, critical appraisal of systematic data on delirium diagnosis, pathophysiology, treatment, prevention, and outcomes is lacking.

PURPOSE

To provide evidence-based recommendations for delirium care to practitioners, and identify gaps in delirium research.

DATA SOURCES

Medline, PubMed, the Cochrane Library, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) information systems from January 1966 to April 2011.

STUDY SELECTION

All published systematic evidence reviews (SERs) on delirium were evaluated.

DATA EXTRACTION

Three reviewers independently extracted the data regarding delirium risk factors, diagnosis, prevention, treatment, and outcomes, and critically appraised each SER as good, fair, or poor using the United States Preventive Services Task Force criteria.

DATA SYNTHESIS

Twenty-two SERs graded as good or fair provided the data. Age, cognitive impairment, depression, anticholinergic drugs, and lorazepam use were associated with an increased risk for developing delirium. The Confusion Assessment Method (CAM) is reliable for delirium diagnosis outside of the intensive care unit. Multicomponent nonpharmacological interventions are effective in reducing delirium incidence in elderly medical patients. Low-dose haloperidol has similar efficacy as atypical antipsychotics for treating delirium. Delirium is associated with poor outcomes independent of age, severity of illness, or dementia.

CONCLUSION

Delirium is an acute, preventable medical condition with short- and long-term negative effects on a patient's cognitive and functional states.

Delirium in elderly people: a review

The present review aims to highlight this intricate syndrome, regarding diagnosis, pathophysiology, etiology, prevention, and management in elderly people. The diagnosis of delirium is based on clinical observations, cognitive assessment, physical, and neurological examination. Clinically, delirium occurs in hyperactive, hypoactive, or mixed forms, based on psychomotor behavior. As an acute confusional state, it is characterized by a rapid onset of symptoms, fluctuating course and an altered level of consciousness, global disturbance of cognition or perceptual abnormalities, and evidence of a physical cause. Although pathophysiological mechanisms of delirium remain unclear, current evidence suggests that disruption of neurotransmission, inflammation, or acute stress responses might all contribute to the development of this ailment. It usually occurs as a result of a complex interaction of multiple risk factors, such as cognitive impairment/dementia and current medical or surgical disorder. Despite all of the above, delirium is frequently under-recognized and often misdiagnosed by health professionals. In particular, this happens due to its fluctuating nature, its overlap with dementia and the scarcity of routine formal cognitive assessment in general hospitals. It is also associated with multiple adverse outcomes that have been well documented, such as increased hospital stay, function/cognitive decline, institutionalization and mortality. In this context, the early identification of delirium is essential. Timely and optimal management of people with delirium should be performed with identification of any possible underlying causes, dealing with a suitable care environment and improving education of health professionals. All these can be important factors, which contribute to a decrease in adverse outcomes associated with delirium.

Pharmacological and nonpharmacological management of delirium in critically ill patients

Delirium is a common yet under-diagnosed syndrome of acute brain dysfunction, which is characterized by inattention, fluctuating mental status, altered level of consciousness, or disorganized thinking. Although our recognition of risk factors for delirium has progressed, our understanding of the underlying pathophysiologic mechanisms remains limited. Improvements in monitoring and assessment for delirium (particularly in the intensive care setting) have resulted in validated and reliable tools such as arousal scales and bedside delirium monitoring instruments. Once delirium is recognized and the modifiable risk factors are addressed, the next step in management (if delirium persists) is often pharmacological intervention. The sedatives, analgesics, and hypnotics most often used in the intensive care unit (ICU) to achieve patient comfort are all too frequently deliriogenic, resulting in a longer duration of ICU and hospital stay, and increased costs. Therefore, identification of safe and efficacious agents to reduce the incidence, duration, and severity of ICU delirium is a hot topic in critical care. Recognizing that there are no medications approved by the Food and Drug Administration (FDA) for the prevention or treatment of delirium, we chose anti-psychotics and alpha-2 agonists as the general pharmacological focus of this article because both were subjects of relatively recent data and ongoing clinical trials. Emerging pharmacological strategies for addressing delirium must be combined with nonpharmacological approaches (such as daily spontaneous awakening trials and spontaneous breathing trials) and early mobility (combined with the increasingly popular approach called: Awakening and Breathing Coordination, Delirium Monitoring, Early Mobility, and Exercise [ABCDE] of critical care) to develop evidence-based approaches that will ensure safer and faster recovery of the sickest patients in our healthcare system.