Cholinergic deficiency hypothesis in delirium: a synthesis of current evidence

An exploratory study of candidate gene(s) for Delirium Tremens: Adding the new cholinergic dimension to the conundrum

BACKGROUND AND AIMS

Delirium Tremens (DT) is the most severe form of alcohol withdrawal syndrome, with a potential risk of mortality. Search for the predictors of DT led to study of candidate genes, with inconsistent and inconclusive results. This study aimed to explore the association of various candidate gene polymorphisms and DT in a case-control design.

METHODS

This was a genetic association study with a case control design. Two hundred ten Alcohol dependent (AD) male subjects and 200 age matched controls were recruited. DT was diagnosed with the help of Semi-structured Assessment for Genetics of Alcoholism. SNP genotyping was done using TaqMan assay by real time PCR (q-PCR).

RESULTS

T allele carrying status (GT and TT) [rs1824024] of muscarinic cholinergic receptor 2 (CHRM2) was found to be significantly associated with DT. When compared to the general population, this genetic polymorphism was not found to be more common in alcohol dependence per se, which excludes the possibility of spurious association between CHRM2 and DT. Withdrawal seizure was more common in the DT group and came out to be one of the important predictors of DT. However, the genetic association was found to be specific for DT, not related to withdrawal seizures.

CONCLUSION

The present research added a new cholinergic dimension in the genetic association and biological mechanism of DT.

Diagnostic accuracy of delirium assessment methods in critical care patients

PURPOSE

Delirium is a disorder of decreased ability to focus, sustain or shift attention, change in cognition and or perception. The main objective was to evaluate the diagnostic accuracy of Confusion Assessment Method for the ICU (CAM-ICU) and Intensive Care Delirium Screening Checklist (ICDSC) among the nursing and medical staff in a multidisciplinary ICU.

METHODS AND MATERIAL

Three hundred ten verbally communicating and non-communicating patients (mean age in years 47.9, standard deviation [SD] 14.5, mean Acute Physiology and Chronic Health Evaluation II score 13.8, SD 6.4) were assessed by a psychiatrist, nurse and intensivist for delirium. Inter-rater agreement was measured by Cohen's kappa coefficient. Sensitivity, specificity, predictive values, likelihood ratios and diagnostic odds ratio (DOR) were calculated.

RESULTS

CAM-ICU showed higher sensitivity and DOR (84%, 86.1) compared to ICDSC (78%, 36.9). ICDSC had specificity and positive predictive value (94.5%, 92%) equal to that of CAM-ICU. For both the assessment methods (CAM-ICU and ICDSC), DORs for intensivists (120.5, 53.0) were relatively higher than nurses (67.0, 27.0).

CONCLUSIONS

In our mixed ICU population, CAM-ICU remained more sensitive than ICDSC. Though sensitivity and DOR were higher for medical staff, other diagnostic parameters were similar for both medical and nursing staff.

Rivastigmine patch reduces the incidence of postoperative delirium in older patients with cognitive impairment

OBJECTIVE

To date, data regarding the efficacy of acetylcholinesterase inhibitors in preventing postoperative delirium (POD) are inconsistent and conflicting. Older individuals with cognitive dysfunction are thought to show POD more frequently. Our aim was to study the effectiveness of rivastigmine prophylaxis on the incidence, severity, and risk factors for POD in older patients with cognitive impairment undergoing hip fracture surgery.

METHODS

Of 62 older patients with cognitive impairment about to undergo surgery after a hip fracture, 31 were randomly assigned to receive a rivastigmine patch from 3 days before to 7 days after the operation (Group I), and the other 31 did not receive a rivastigmine patch (Group II). The two groups were compared with regard to incidence and severity of delirium on postoperative days 2 or 3 and 7. Multivariate logistic regression analysis was performed to assess factors associated with POD.

RESULTS

Postoperative delirium occurred in five Group I patients and 14 Group II patients (p = 0.013). The mean severity of delirium in the two groups as determined by the Delirium Rating Scale was 2.2 and 6.2 respectively (p = 0.033). The odds ratio for POD was 0.259 (95% CI: 0.074-0.905, p = 0.034) after adjusting for American Society of Anesthesiologists score (p = 0.058), age (p = 0.203), and gender (p = 0.560). There were no rivastigmine-related perioperative complications.

CONCLUSION

Perioperative rivastigmine patch application could reduce the occurrence of POD in older patients with low cognitive status. Copyright © 2016 John Wiley & Sons, Ltd.

Delirium in Pediatric Critical Care

Delirium occurs frequently in the critically ill child. It is a syndrome characterized by an acute onset and fluctuating course, with behaviors that reflect a disturbance in awareness and cognition. Delirium represents global cerebral dysfunction due to the direct physiologic effects of an underlying medical illness or its treatment. Pediatric delirium is strongly associated with poor outcomes, including increased mortality, prolonged intensive care unit length of stay, longer time on mechanical ventilation, and increased cost of care. With heightened awareness, the pediatric intensivist can detect, treat, and prevent delirium in at-risk children.

Differentiating Delirium From Sedative/Hypnotic-Related Iatrogenic Withdrawal Syndrome: Lack of Specificity in Pediatric Critical Care Assessment Tools

OBJECTIVES

To identify available assessment tools for sedative/hypnotic iatrogenic withdrawal syndrome and delirium in PICU patients, the evidence supporting their use, and describe areas of overlap between the components of these tools and the symptoms of anticholinergic burden in children.

DATA SOURCES

Studies were identified using PubMed and EMBASE from the earliest available date until July 3, 2016, using a combination of MeSH terms "delirium," "substance withdrawal syndrome," and key words "opioids," "benzodiazepines," "critical illness," "ICU," and "intensive care." Review article references were also searched.

STUDY SELECTION

Human studies reporting assessment of delirium or iatrogenic withdrawal syndrome in children 0-18 years undergoing critical care. Non-English language, exclusively adult, and neonatal intensive care studies were excluded.

DATA EXTRACTION

References cataloged by study type, population, and screening process.

DATA SYNTHESIS

Iatrogenic withdrawal syndrome and delirium are both prevalent in the PICU population. Commonly used scales for delirium and iatrogenic withdrawal syndrome assess signs and symptoms in the motor, behavior, and state domains, and exhibit considerable overlap. In addition, signs and symptoms of an anticholinergic toxidrome (a risk associated with some common PICU medications) overlap with components of these scales, specifically in motor, cardiovascular, and psychiatric domains.

CONCLUSIONS

Although important studies have demonstrated apparent high prevalence of iatrogenic withdrawal syndrome and delirium in the PICU population, the overlap in these scoring systems presents potential difficulty in distinguishing syndromes, both clinically and for research purposes.

Anticholinergic drug exposure is associated with delirium and postdischarge institutionalization in acutely ill hospitalized older patients

Several studies investigated the possible association between anticholinergic drugs and diverse clinical outcomes in older persons, but the results are inconsistent. The aim of this study was to investigate whether anticholinergic drug exposure is associated with delirium on admission, length of hospital stay, postdischarge institutionalization and in-hospital mortality in acutely ill hospitalized older patients. In this observational chart review study, we included acutely ill patients aged 65 and older who were admitted to the geriatric ward of the Erasmus University Medical Center, Rotterdam, The Netherlands, between 2012 and 2015 (n = 905). Anticholinergic drug exposure on admission was defined as the use of anticholinergic drugs, total number of anticholinergic drugs and anticholinergic drug burden score (ADB), quantified with the Anticholinergic Risk Scale (ARS), the Anticholinergic Cognitive Burden scale (ACB) and the list of Chew et al. (Chew). Logistic regression analyses were performed to investigate possible associations between anticholinergic drug exposure and the aforementioned outcomes. Analyses were adjusted for age, sex, comorbidities, non-anticholinergic drugs and delirium, where appropriate. Moderate and high ADB measured with the ARS were associated with delirium on admission with odds ratios (OR) of 1.70 (95% confidence interval (CI) = 1.16-2.49) and 1.83 (95% CI = 1.06-3.15), respectively. High ADB measured with the ARS was also associated with postdischarge institutionalization (OR = 2.43, 95% CI = 1.24-4.75). No associations were found using the ACB and Chew. Future studies are warranted to investigate the clinical usefulness of the ARS in reducing complications in older persons.

Polypharmacy and Delirium in Critically Ill Older Adults: Recognition and Prevention

Among older adults, polypharmacy is a sequelae of admission to the intensive care unit and is associated with increased medication-associated adverse events, drug interactions, and health care costs. Delirium is prevalent in critically ill geriatric patients and medications remain an underappreciated modifiable risk for delirium in this setting. This article reviews the literature on polypharmacy and delirium, with a focus on highlighting the relationships between polypharmacy and delirium in critically ill, older adults. Discussed are clinician strategies on how to recognize and reduce medication-associated delirium and recommendations that help prevent polypharmacy when interventions to reduce the burden of delirium in this vulnerable population are being formulated.

Impact of dexmedetomidine on the incidence of delirium in elderly patients after cardiac surgery: A randomized controlled trial

Background

Delirium is a frequent complication after cardiac surgery and its occurrence is associated with poor outcomes. The purpose of this study was to investigate the impact of perioperative dexmedetomidine administration on the incidence of delirium in elderly patients after cardiac surgery.

Methods

This randomized, double-blinded, and placebo-controlled trial was conducted in two tertiary hospitals in Beijing between December 1, 2014 and July 19, 2015. Eligible patients were randomized into two groups. Dexmedetomidine (DEX) was administered during anesthesia and early postoperative period for patients in the DEX group, whereas normal saline was administered in the same rate for the same duration for patients in the control (CTRL) group. The primary endpoint was the incidence of delirium during the first five days after surgery. Secondary endpoints included the cognitive function assessed on postoperative days 6 and 30, the overall incidence of non-delirium complications within 30 days after surgery, and the all-cause 30-day mortality.

Results

Two hundred eighty-five patients were enrolled and randomized. Dexmedetomidine did not decrease the incidence of delirium (4.9% [7/142] in the DEX group vs 7.7% [11/143] in the CTRL group; OR 0.62, 95% CI 0.23 to 1.65, p = 0.341). Secondary endpoints were similar between the two groups; however, the incidence of pulmonary complications was slightly decreased (OR 0.51, 95% CI 0.26 to 1.00, p = 0.050) and the percentage of early extubation was significantly increased (OR 3.32, 95% CI 1.36 to 8.08, p = 0.008) in the DEX group. Dexmedetomidine decreased the required treatment for intraoperative tachycardia (21.1% [30/142] in the DEX group vs 33.6% [48/143] in the CTRL group, p = 0.019), but increased the required treatment for postoperative hypotension (84.5% [120/142] in the DEX group vs 69.9% [100/143] in the CTRL group, p = 0.003).

Conclusions

Dexmedetomidine administered during anesthesia and early postoperative period did not decrease the incidence of postoperative delirium in elderly patients undergoing elective cardiac surgery. However, considering the low delirium incidence, the trial might have been underpowered.

Trial Registration

ClinicalTrials.gov NCT02267538

Increased Symptom Expression among Patients with Delirium Admitted to an Acute Palliative Care Unit

INTRODUCTION

Delirium is the most common neuropsychiatric condition in very ill patients and those at the end of life. Previous case reports found that delirium-induced disinhibition may lead to overexpression of symptoms. It negatively affects communication between patients, family members, and the medical team and can sometimes lead to inappropriate interventions. Better understanding would result in improved care. Our aim was to determine the effect of delirium on the reporting of symptom severity in patients with advanced cancer.

METHODS

We reviewed 329 consecutive patients admitted to the acute palliative care unit (APCU) without a diagnosis of delirium from January to December 2011. Demographics, Memorial Delirium Assessment Scale, Eastern Cooperative Oncology Group (ECOG) Performance status, and Edmonton Symptom Assessment Scale (ESAS) on two time points were collected. The first time point was on admission and the second time point for group A was day one (+two days) of delirium. For group B, the second time point was within two to four days before discharge from the APCU. Patients who developed delirium and those who did not develop delirium during the entire course of admission were compared using chi-squared test and Wilcoxon rank-sum test. Paired t-test was used to assess if the change of ESAS from baseline to follow-up was associated with delirium.

RESULTS

Ninety-six of 329 (29%) patients developed delirium during their admission to the APCU. The median time to delirium was two days. There was no difference in the length of stay in the APCU for both groups. Patients who did not have delirium expressed improvement in all their symptoms, while those who developed delirium during hospitalization showed no improvement in physical symptoms and worsening in depression, anxiety, appetite, and well-being.

CONCLUSION

Patients with delirium reported no improvement or worsening symptoms compared to patients without delirium. Screening for delirium is important in patients who continue to report worsening symptoms despite appropriate management.

Delirium in the Intensive Care Unit

Delirium is characterized by impaired cognition with nonspecific manifestations. In critically ill patients, it may develop secondary to multiple precipitating or predisposing causes. Although it can be a transient and reversible syndrome, its occurrence in Intensive Care Unit (ICU) patients may be associated with long-term cognitive dysfunction. This condition is often under-recognized by treating physicians, leading to inappropriate management. For appropriate management of delirium, early identification and risk factor assessment are key factors. Multidisciplinary collaboration and standardized care can enhance the recognition of delirium. Interdisciplinary team working, together with updated guideline implementation, demonstrates proven success in minimizing delirium in the ICU. Moreover, should the use of physical restraint be necessary to prevent harm among mechanically ventilated patients, ethical clinical practice methodology must be employed. This traditional narrative review aims to address the presentation, risk factors, management, and ethical considerations in the management of delirium in ICU settings.

Hyperbaric oxygen preconditioning improves postoperative cognitive dysfunction by reducing oxidant stress and inflammation

Postoperative cognitive dysfunction is a crucial public health issue that has been increasingly studied in efforts to reduce symptoms or prevent its occurrence. However, effective advances remain lacking. Hyperbaric oxygen preconditioning has proved to protect vital organs, such as the heart, liver, and brain. Recently, it has been introduced and widely studied in the prevention of postoperative cognitive dysfunction, with promising results. However, the neuroprotective mechanisms underlying this phenomenon remain controversial. This review summarizes and highlights the definition and application of hyperbaric oxygen preconditioning, the perniciousness and pathogenetic mechanism underlying postoperative cognitive dysfunction, and the effects that hyperbaric oxygen preconditioning has on postoperative cognitive dysfunction. Finally, we conclude that hyperbaric oxygen preconditioning is an effective and feasible method to prevent, alleviate, and improve postoperative cognitive dysfunction, and that its mechanism of action is very complex, involving the stimulation of endogenous antioxidant and anti-inflammation defense systems.

Delirium in critically ill patients

Delirium is common in critically ill patients and associated with increased length of stay in the intensive care unit (ICU) and long-term cognitive impairment. The pathophysiology of delirium has been explained by neuroinflammation, an aberrant stress response, neurotransmitter imbalances, and neuronal network alterations. Delirium develops mostly in vulnerable patients (e.g., elderly and cognitively impaired) in the throes of a critical illness. Delirium is by definition due to an underlying condition and can be identified at ICU admission using prediction models. Treatment of delirium can be improved with frequent monitoring, as early detection and subsequent treatment of the underlying condition can improve outcome. Cautious use or avoidance of benzodiazepines may reduce the likelihood of developing delirium. Nonpharmacologic strategies with early mobilization, reducing causes for sleep deprivation, and reorientation measures may be effective in the prevention of delirium. Antipsychotics are effective in treating hallucinations and agitation, but do not reduce the duration of delirium. Combined pain, agitation, and delirium protocols seem to improve the outcome of critically ill patients and may reduce delirium incidence.

Baseline acetylcholinesterase activity and serotonin plasma levels are not associated with delirium in critically ill patients

Objective

The aim of this study was to investigate whether plasma serotonin levels or acetylcholinesterase activities determined upon intensive care unit admission could predict the occurrence of acute brain dysfunction in intensive care unit patients.

Methods

A prospective cohort study was conducted with a sample of 77 non-consecutive patients observed between May 2009 and September 2010. Delirium was determined using the Confusion Assessment Method for the Intensive Care Unit tool, and the acetylcholinesterase and serotonin measurements were determined from blood samples collected up to a maximum of 24 h after the admission of the patient to the intensive care unit.

Results

In the present study, 38 (49.6%) patients developed delirium during their intensive care unit stays. Neither serum acetylcholinesterase activity nor serotonin level was independently associated with delirium. No significant correlations of acetylcholinesterase activity or serotonin level with delirium/coma-free days were observed, but in the patients who developed delirium, there was a strong negative correlation between the acetylcholinesterase level and the number of delirium/coma-free days, indicating that higher acetylcholinesterase levels are associated with fewer days alive without delirium or coma. No associations were found between the biomarkers and mortality.

Conclusions

Neither serum acetylcholinesterase activity nor serotonin level was associated with delirium or acute brain dysfunction in critically ill patients. Sepsis did not modify these relationships.

Smoking Cessation and the Risk of Hyperactive Delirium in Hospitalized Patients: A Retrospective Study

OBJECTIVES

The acute cessation of smoking often induces symptoms that are similar to those associated with delirium. We aimed to evaluate effects of sudden nicotine abstinence on the development of delirium and its motoric subtypes in hospitalized patients.

METHODS

The present study included patients who were referred to psychiatrists by ward physicians due to confusion. The presence of delirium was defined using the Confusion Assessment Method and the Delirium Rating Scale Revised-98, which was also used to assess the severity of delirium. Outcome variables, including the length of hospital stay and 3-month mortality rate, were collected by a retrospective chart review.

RESULTS

Delirium was confirmed in 210 of the 293 referred patients. Of the motoric subtypes of delirium, the hyperactive subtype was more common (68.1%) and was related to higher 3-month mortality (odds ratio [OR], 2.189; 95% confidence interval [CI], 1.07 to 4.49; P = 0.033) compared with hypoactive delirium. Patients undergoing sudden cessation of smoking (n = 55) were more likely to exhibit hyperactive delirium than were nonsmokers (P = 0.001). A multivariate analysis revealed that smoking cessation was an independent risk factor for hyperactive delirium (OR, 10.33; 95% CI, 2.31 to 46.09; P = 0.002). In addition, the amount of smoking was positively correlated with the severity of hyperactivity (r = 0.421, P = 0.003). Smoking status did not significantly influence overall delirium incidence.

CONCLUSIONS

The present findings demonstrated that nicotine withdrawal was associated with hyperactive delirium, which suggests that they share common pathophysiologies that involve the dopamine, opioid, and cholinergic systems.

Mini Review: Anticholinergic Activity as a Behavioral Pathology of Lewy Body Disease and Proposal of the Concept of "Anticholinergic Spectrum Disorders"

Given the relationship between anticholinergic activity (AA) and Alzheimer's disease (AD), we rereview our hypothesis of the endogenous appearance of AA in AD. Briefly, because acetylcholine (ACh) regulates not only cognitive function but also the inflammatory system, when ACh downregulation reaches a critical level, inflammation increases, triggering the appearance of cytokines with AA. Moreover, based on a case report of a patient with mild AD and slightly deteriorated ACh, we also speculate that AA can appear endogenously in Lewy body disease due to the dual action of the downregulation of ACh and hyperactivity of the hypothalamic-pituitary-adrenal axis. Based on these hypotheses, we consider AA to be a behavioral pathology of Lewy body disease. We also propose the concept of “anticholinergic spectrum disorders,” which encompass a variety of conditions, including AD, Lewy body disease, and delirium. Finally, we suggest the prescription of cholinesterase inhibitors to patients in this spectrum of disorders to abolish AA by upregulating ACh.

Delirium is not associated with anticholinergic burden or polypharmacy in older patients on admission to an acute hospital: an observational case control study

Background

Older people are commonly prescribed multiple medications, including medications with anticholinergic effects. Polypharmacy and anticholinergic medications may be risk factors for the development of delirium.

Methods

Patients from a medical admission unit who were over 70, with DSM-IV diagnosed delirium and patients without delirium, were investigated. Number of drugs prescribed on admission and anticholinergic burden using two scales (the Anticholinergic Cognitive Burden Scale [ACB] and the Anticholinergic Drug Scale [ADS]) were recorded from electronic prescribing records. The relationship and predictive ability of these were explored.

Results

The sample included 125 patients with DSM-IV diagnosed delirium and 122 patients without delirium. The mean age of the sample was 84.0 years. The median number of drugs prescribed was 7: 79.8 % were prescribed ≥5 drugs and 29.0 % ≥10 drugs. The median ACB score was 1 and the median ADS score was 1.5. 73.4 % of patients had an ACB score of ≥1 and 73.0 % had a ADS score ≥1. There was no association between: number of drugs prescribed, rate of polypharmacy, rate of excessive polypharmacy, ACB score and ADS score, and a diagnosis of delirium on admission. Only acetylcholinesterase inhibitor use predicted delirium (OR 3.86, p = 0.04) and the number of drugs prescribed was negatively correlated with age (spearman rho = −0.18, p = 0.006).

Conclusion

Neither number of drugs prescribed, polypharmacy or anticholinergic burden were associated with delirium on admission, questioning the clinical usefulness of anticholinergic drug scales. Further research is needed to unpick fully the relationship between, drugs, anticholinergic burden, age, and prevalent delirium in older patients and whether there is any role for these scales in clinical practice.

Electronic supplementary material

The online version of this article (doi:10.1186/s12877-016-0336-9) contains supplementary material, which is available to authorized users.

Neural circuitry and immunity

Research during the last decade has significantly advanced our understanding of the molecular mechanisms at the interface between the nervous system and the immune system. Insight into bidirectional neuro-immune communication has characterized the nervous system as an important partner of the immune system in the regulation of inflammation. Neuronal pathways, including the vagus nerve-based inflammatory reflex, are physiological regulators of immune function and inflammation. In parallel, neuronal function is altered in conditions characterized by immune dysregulation and inflammation. Here, we review these regulatory mechanisms and describe the neural circuitry modulating immunity. Understanding these mechanisms reveals possibilities to use targeted neuromodulation as a therapeutic approach for inflammatory and autoimmune disorders. These findings and current clinical exploration of neuromodulation in the treatment of inflammatory diseases define the emerging field of Bioelectronic Medicine.

Comparative Study of Delirium in Emergency and Consultation Liaison- A Tertiary Care Hospital Based Study in Northern India

INTRODUCTION

Delirium is an acute and often fluctuating disturbance in level of consciousness and thought process (cognition) that develops over a short period of time and is a significant change from previous level of functioning. Its prevalence increases with age, complexity of medical co- morbidities and number of medications prescribed.

AIM

To compare the cause and severity of delirium in patients in emergency and consultation liaison psychiatry group.

MATERIALS AND METHODS

A cross-sectional, tertiary care hospital based study was conducted on the patients who presented with delirium from emergency department (50) and consultation-liaison psychiatry groups (50), over a period of one year. The diagnosis was made on the basis of DSM- 5 criteria. The Delirium Rating Scale (DRS-R-98) was applied to know the severity of delirium, cognitive and non-cognitive symptoms of delirium in patients. The results were subjected to appropriate statistical analysis.

RESULTS

In emergency group, 42% patients had metabolic abnormalities, while in consultation-liaison, 38% patients had hyponatremia and hypokalemia and the difference was found to be statistically non-significant (p>0.05). In emergency group, 21(42%) patients were diagnosed as delirium due to other medical condition, followed by 13 (26%) and 8(16%) patients, who were diagnosed as delirium due to multiple aetiologies and substance intoxication each respectively. In only 33(66%) cases in consultation liaison group patients had delirium secondary to other medical conditions. As per DRS-R98 Scale, mean severity score was found to be statistically significant (p<0.05) in consultation liaison group as compared to emergency department group (p> 0.05).

CONCLUSION

Delirium is multifactorial aetiological disease, with variable but preventable outcome. Approach should be aimed at finding the treatable causes to reduce morbidity and mortality.

Drug-induced cognitive impairment: Effect of cardiovascular agents

INTRODUCTION

Cardiovascular agents can be associated with a negative effect on cognition, especially in older adults, critically ill people, and those with baseline cognitive impairment. Negative effect on cognition is commonly reported as uncomplicated acute confusion and delirium and, less commonly, chronic cognitive changes due to drug-induced depression and/or dementia.

METHODS

A literature review of case reports, case series, prospective cohort studies, clinical trials, and literature reviews were included in this study. Articles were located using online databases PubMed and Medline using the following keywords: antiarrhythmic agents, anticholinergic burden, antihypertensive agents, beta-blockers, cardiovascular agents, cognitive impairment, delirium, cognition, dementia, depression, digoxin, diuretics, and drug-induced cognitive impairment.

RESULTS

In general, use of all antihypertensives, especially in the case of polypharmacy or inappropriate dosing, can lead to hypotension and/or bradycardia, and thus lead to mental/cognitive status change due to decreased cerebral perfusion. Use of diuretics can be associated with fluid/electrolyte and/or acid-base imbalance, resulting in the onset of confusion and delirium. In addition, cardiovascular agents with central bioavailability, such digoxin and select antiarrhythmics, and antihypertensives may carry a risk for cognitive impairment due to various mechanisms proposed, such as antagonism of central muscarinic acetylcholine receptors, neurotransmission imbalance in the brain, and disruption of physiologic function of sodium/potassium ATPase in the neuronal cells.

DISCUSSION

When dealing with an individual who presents with acute, subacute, and chronic changes in cognitive function, one should perform a thorough medication history as the first step in order to aid in the identification of drug-induced cognitive impairment.

Acetylcholinesterase Inhibitors for Delirium in Older Adults

OBJECTIVES

The aim of this systematic review is to identify published randomized controlled trials (RCTs) that evaluated the use of acetylcholinesterase inhibitors for delirium in older adults (≥60 years).

METHODS

A literature search was conducted of PubMed, MEDLINE, EMBASE, PsycINFO, and Cochrane collaboration databases for RCTs in any language that evaluated the use of acetylcholinesterase inhibitors for delirium in older adults (≥60 years). Also, bibliographic databases of the published articles were searched for additional studies.

RESULTS

A total of 7 RCTs that evaluated the use of acetylcholinesterase inhibitors for delirium in older adults (≥60 years) were identified. In 5 of the 7 studies, there was no benefit for the acetylcholinesterase inhibitor in either the prevention or the management of delirium. In one study, there was a trend toward benefit for the active drug group on the incidence of delirium and the length of hospital stay, but both outcomes did not attain statistical significance. One study found a longer duration of delirium and a longer length of hospital stay in the active drug group when compared to the placebo group. The acetylcholinesterase inhibitors were well tolerated in 4 of the 7 studies. In 1 study, the mortality rate was found to be almost 3 times higher in the group receiving haloperidol and rivastigmine when compared to the group receiving haloperidol and placebo.

CONCLUSION

Current evidence does not suggest efficacy of acetylcholinesterase inhibitors for the prevention or management of delirium in older adults.

Predicting outcome in older hospital patients with delirium: a systematic literature review

OBJECTIVE

Delirium is a serious neuropsychiatric syndrome common in older hospitalised adults. It is associated with poor outcomes, however not all people with delirium have poor outcomes and the risk factors for adverse outcomes within this group are not well described. The objective was to report which predictors of outcome had been reported in the literature.

METHODS

We performed a systematic review by an initial electronic database search of MEDLINE, Embase and PsycINFO using four key search criteria. These were: (1) participants with a diagnosis of delirium, (2) clearly defined outcome measures, (3) a clearly defined variable as predictor of outcomes and (4) participants in the general hospital, rehabilitation and care home settings, excluding intensive care. Studies were then selected in a systematic fashion using specific predetermined criteria by three reviewers.

RESULTS

A total of 559 articles were screened, and 57 full text articles were assessed for eligibility. Twenty seven studies describing 18 different predictors of poor outcome were reported. The studies were rated by the Newcastle-Ottawa Score and were generally at low risk of bias. Four broad themes of predictor were identified; five delirium related predictors, two co-morbid psychiatric illness related predictors, eight patient related predictors and three biomarker related predictors. The most numerously described and clinically important appear to be the duration of the delirium episode, a hypoactive motor subtype, delirium severity and pre-existing psychiatric morbidity with dementia or depression. These are all associated with poorer delirium outcomes.

CONCLUSION

Important predictors of poor outcomes in patients with delirium have been demonstrated. These could be used in clinical practice to focus direct management and guide discussions regarding prognosis. These results also demonstrate a number of key unknowns, where further research to explore delirium prognosis is recommended and is vital to improve understanding and management of this condition.

Serum protein S100 as marker of postoperative delirium after off-pump coronary artery bypass surgery: secondary analysis of two prospective randomized controlled trials

Background:

To investigate the predictive value of S100 (biochemical marker of neuroglial injury) for the occurrence of postoperative delirium (POD) in patients undergoing off-pump coronary artery bypass (OPCAB)-surgery.

Methods:

We enrolled 92 patients older than 18 years undergoing elective OPCAB-surgery. Serum-levels of S100 were determined at baseline (BL), end of surgery (EOS) and on the first postoperative day (PD1). Postoperatively, all-patients were evaluated daily until PD5 for the presence of POD using the confusion assessment method (CAM) or the confusion assessment method for the intensive care unit (CAM-ICU) for patients in the intensive care unit (ICU).

Results:

The overall incidence of POD was 21%. S100-values on PD1 significantly predicted the occurrence of POD during the later hospital stay [area under the curve (AUC)=0.724 (95% confidence interval (CI): 0.619–0.814); p=0.0001] with an optimal cut-off level of 123 pg mL

Conclusions:

S100-levels <123 pg mL

Pharmacological management of anticholinergic delirium - theory, evidence and practice

The spectrum of anticholinergic delirium is a common complication following drug overdose. Patients with severe toxicity can have significant distress and behavioural problems that often require pharmacological management. Cholinesterase inhibitors, such as physostigmine, are effective but widespread use has been limited by concerns about safety, optimal dosing and variable supply. Case series support efficacy in reversal of anticholinergic delirium. However doses vary widely and higher doses commonly lead to cholinergic toxicity. Seizures are reported in up to 2.5% of patients and occasional cardiotoxic effects are also recorded. This article reviews the serendipitous path whereby physostigmine evolved into the preferred anticholinesterase antidote largely without any research to indicate the optimal dosing strategy. Adverse events observed in case series should be considered in the context of pharmacokinetic/pharmacodynamic studies of physostigmine which suggest a much longer latency before the maximal increase in brain acetylcholine than had been previously assumed. This would favour protocols that use lower doses and longer re-dosing intervals. We propose based on the evidence reviewed that the use of cholinesterase inhibitors should be considered in anticholinergic delirium that has not responded to non-pharmacological delirium management. The optimal risk/benefit would be with a titrated dose of 0.5 to 1 mg physostigmine (0.01-0.02 mg kg(-1) in children) with a minimum delay of 10-15 min before re-dosing. Slower onset and longer acting agents such as rivastigmine would also be logical but more research is needed to guide the appropriate dose in this setting.

Cyproheptadine for the Prevention of Postoperative Delirium: A Pilot Study

BACKGROUND

Postoperative delirium is a common neurobehavioral complication after major surgeries. There is no conclusive approach for prevention of delirium in these patients.

OBJECTIVE

In this study, efficacy of cyproheptadine for prevention of postoperative delirium was evaluated.

METHODS

Delirium status of surgical patients was evaluated postoperatively at the time of admission to the intensive care unit (ICU) using the Confusion Assessment Method (CAM-ICU) scale. Patients without delirium were assigned to the cyproheptadine or placebo group based on the simple randomization method. Patients received cyproheptadine or placebo tablet at a dose of 4 mg 3 times per day for 7 days. Patients were monitored daily for incidence of delirium.

RESULTS

Changes in the incidence rates of delirium over time during the study phase (P = 0.04) and between the groups showed statistically significant differences (P = 0.029). However, severity of delirium was not significantly different between the cyproheptadine and placebo groups during the study period.

CONCLUSION

It seems that cyproheptadine with its diverse effects can be a potential option for prevention of postoperative delirium. In this pilot study, cyproheptadine significantly decreased the incidence but not severity of postoperative delirium.

Disturbed Serotonergic Neurotransmission and Oxidative Stress in Elderly Patients with Delirium

Background

Oxidative stress and disturbances in serotonergic and dopaminergic neurotransmission may play a role in the pathophysiology of delirium.

Aims

In this study, we investigated levels of amino acids, amino acid ratios and levels of homovanillic acid (HVA) as indicators for oxidative stress and disturbances in neurotransmission.

Methods

Plasma levels of amino acids, amino acid ratios and HVA were determined in acutely ill patients aged ≥65 years admitted to the wards of Internal Medicine and Geriatrics of the Erasmus University Medical Center and the ward of Geriatrics of the Havenziekenhuis, Rotterdam, The Netherlands. Differences in the biochemical parameters between patients with and without delirium were investigated by analysis of variance in models adjusted for age, gender and comorbidities.

Results

Of the 86 patients included, 23 had delirium. In adjusted models, higher mean phenylalanine/tyrosine ratios (1.34 vs. 1.14, p = 0.028), lower mean tryptophan/large neutral amino acids ratios (4.90 vs. 6.12, p = 0.021) and lower mean arginine levels (34.8 vs. 45.2 µmol/l, p = 0.022) were found in patients with delirium when compared to those without. No differences were found in HVA levels between patients with and without delirium.

Conclusion

The findings of this study suggest disturbed serotonergic neurotransmission and an increased status of oxidative stress in patients with delirium.

Muscarinic M1 receptors modulate endotoxemia-induced loss of synaptic plasticity

Septic encephalopathy is associated with rapid deterioration of cortical functions. Using magnetic resonance imaging (MRI) we detected functional abnormalities in the hippocampal formation of patients with septic delirium. Hippocampal dysfunction was further investigated in an animal model for sepsis using lipopolysaccharide (LPS) injections to induce endotoxemia in rats, followed by electrophysiological recordings in brain slices. Endotoxemia induced a deficit in long term potentiation which was completely reversed by apamin, a blocker of small conductance calcium-activated potassium (SK) channels, and partly restored by treatment with physostigmine (eserine), an acetylcholinesterase inhibitor, or TBPB, a selective M1 muscarinic acetylcholine receptor agonist. These results suggest a novel role for SK channels in the etiology of endotoxemia and explain why boosting cholinergic function restores deficits in synaptic plasticity. Drugs which enhance cholinergic or M1 activity in the brain may prove beneficial in treatment of septic delirium in the intensive care unit.

Delirium Accompanied by Cholinergic Deficiency and Organ Failure in a 73-Year-Old Critically Ill Patient: Physostigmine as a Therapeutic Option

Delirium is a common problem in ICU patients, resulting in prolonged ICU stay and increased mortality. A cholinergic deficiency in the central nervous system is supposed to be a relevant pathophysiologic process in delirium. Acetylcholine is a major transmitter of the parasympathetic nervous system influencing several organs (e.g., heart and kidneys) and the inflammatory response too. This perception might explain that delirium is not an individual symptom, but rather a part of a symptom complex with various disorders of the whole organism. The cholinergic deficiency could not be quantified up to now. Using the possibility of bedside determination of the acetylcholinesterase activity (AChE activity), we assumed to objectify the cholinergic homeostasis within minutes. As reported here, the postoperative delirium was accompanied by a massive hemodynamic and renal deterioration of unclear genesis. We identified the altered AChE activity as a plausible pathophysiological mechanism. The pharmacological intervention with the indirect parasympathomimetic physostigmine led to a quick and lasting improvement of the patient's cognitive, hemodynamic, and renal status. In summary, severe delirium is not always an attendant phenomenon of critical illness. It might be causal for multiple organ deterioration if it is based on cholinergic deficiency and has to be treated at his pathophysiological roots whenever possible.

Xenon for the prevention of postoperative delirium in cardiac surgery: study protocol for a randomized controlled clinical trial

Background

Postoperative delirium (POD) is a manifestation of acute postoperative brain dysfunction that is frequently observed after cardiac surgery. POD is associated with short-term complications such as an increase in mortality, morbidity, costs and length of stay, but can also have long-term sequelae, including persistent cognitive deficits, loss of independence, and increased mortality for up to 2 years. The noble gas xenon has been demonstrated in various models of neuronal injury to exhibit remarkable neuroprotective properties. We therefore hypothesize that xenon anesthesia reduces the incidence of POD in elderly patients undergoing cardiac surgery with the use of cardiopulmonary bypass.

Methods/Design

One hundred and ninety patients, older than 65 years, and scheduled for elective cardiac surgery, will be enrolled in this prospective, randomized, controlled trial. Patients will be randomized to receive general anesthesia with either xenon or sevoflurane. Primary outcome parameter will be the incidence of POD in the first 5 postoperative days. The occurrence of POD will be assessed by trained research personnel, blinded to study group, with the validated 3-minute Diagnostic Confusion Assessment Method (3D-CAM) (on the intensive care unit in its version specifically adapted for the ICU), in addition to chart review and the results of delirium screening tools that will be performed by the bedside nurses). Secondary outcome parameters include duration and severity of POD, and postoperative cognitive function as assessed with the Mini-Mental State Examination.

Discussion

Older patients undergoing cardiac surgery are at particular risk to develop POD. Xenon provides remarkable hemodynamic stability and has been suggested in preclinical studies to exhibit neuroprotective properties. The present trial will assess whether the promising profile of xenon can be translated into a better outcome in the geriatric population.

Trial registration

EudraCT Identifier: 2014-005370-11 (13 May 2015).

Preoperative risk factors for postoperative delirium following hip fracture repair: a systematic review

OBJECTIVE

Systematically identify preoperative clinical risk factors for incident postoperative delirium in individuals undergoing hip fracture repair in order to guide clinicians in identifying high risk patients at admission.

METHODS

This is a systematic review of prospective observational studies with estimation of association between preoperative risk factors and incident postoperative delirium in multivariate models. Electronic searches were conducted in PubMed, Embase, PsycINFO, CINAHL, Cochrane Library, Proquest Dissertations and Theses, and WorldCatDissertations. Hand searches were conducted in selected journals and their supplements.

RESULTS

Search yielded 6380 titles and abstracts from electronic databases and 72 titles from hand searches, and 10 studies met inclusion criteria. The following risk factors were significant in bivariate models: cognitive impairment, age, gender, institutionalization, functional impairment, body mass index (BMI), albumin, comorbidities, American Society of Anesthesiologist classification, acute medical conditions, polypharmacy, and vision impairment. Among all of these risk factors, cognitive impairment most consistently remained statistically significant after adjusting for other risk factors in multivariate models, followed by BMI/albumin and multiple comorbidities.

CONCLUSION

In our systematic review, cognitive impairment was one of the strongest preoperative risk factors for postoperative delirium after hip fracture surgery. Preoperative cognitive assessment may be one of the most useful methods of identifying those who are at high risk for postoperative delirium and prioritizing delivery of delirium prevention measures.

The acetylcholine index: an electroencephalographic marker of cholinergic activity in the living human brain applied to Alzheimer's disease and other dementias

BACKGROUND

The cholinergic hypothesis is well established and has led to the development of pharmacological treatments for Alzheimer's disease (AD). However, there has previously been no physiological means of monitoring cholinergic activity in vivo.

METHODS

An electroencephalography (EEG)-based acetylcholine (Ach) index reflecting the cholinergic activity in the brain was developed using data from a scopolamine challenge study. The applicability of the Ach index was examined in an elderly population of healthy controls and patients suffering from various causes of cognitive decline.

RESULTS

The Ach index showed a strong reduction in the severe stages of AD dementia. A high correlation was demonstrated between the Ach index and cognitive function. The index was reduced in patients with mild cognitive impairment and prodromal AD, indicating a decreased cholinergic activity. When considering the distribution of the Ach index in a population of healthy elderly subjects, an age-related threshold was revealed, beyond which there is a general decline in cholinergic activity.

CONCLUSIONS

The EEG-based Ach index provides, for the first time, a physiological means of monitoring the cholinergic activity in the human brain in vivo. This has great potential for aiding diagnosis and patient stratification as well as for monitoring disease progression and treatment response.

Cytokines and Postoperative Delirium in Older Patients Undergoing Major Elective Surgery

BACKGROUND

A proinflammatory state has been associated with several age-associated conditions; however, the inflammatory mechanisms of delirium remain poorly characterized.

METHODS

Using the Successful Aging after Elective Surgery Study of adults age ≥70 undergoing major noncardiac surgery, 12 cytokines were measured at four timepoints: preoperative, postanesthesia care unit, postoperative day 2 (POD2) and 30 days later (POD1M). We conducted a nested, longitudinal matched (on age, sex, surgery type, baseline cognition, vascular comorbidity, and Apolipoprotein E genotype) case-control study: delirium cases and no-delirium controls were selected from the overall cohort (N = 566; 24% delirium). Analyses were independently conducted in discovery, replication, and pooled cohorts (39, 36, 75 matched pairs, respectively). Nonparametric signed-rank tests evaluating differences in cytokine levels between matched pairs were used to identify delirium-associated cytokines.

RESULTS

In the discovery and replication cohorts, matching variables were similar in cases and controls. Compared to controls, cases had (*p < .05, **p < .01) significantly higher interleukin-6 on POD2 in the discovery, replication, and pooled cohorts (median difference [pg/mL] 50.44**, 20.17*, 39.35**, respectively). In the pooled cohort, cases were higher than controls for interleukin-2 (0.99*, 0.77*, 1.07**, 0.73* at preoperative, postanesthesia care unit, POD2, POD1M, respectively), vascular endothelial growth factor (4.10* at POD2), and tumor necrosis factor-alpha (3.10* at POD1M), while cases had lower interleukin-12 at POD1M (-4.24*).

CONCLUSIONS

In this large, well-characterized cohort assessed at multiple timepoints, we observed an inflammatory signature of delirium involving elevated interleukin-6 at POD2, which may be an important disease marker for delirium. We also observed preliminary evidence for involvement of other cytokines.

Neopterin: a potential biomarker for delirium in elderly patients

BACKGROUND/AIMS

The diagnosis of delirium is not supported by specific biomarkers. In a previous study, high neopterin levels were found in patients with a postoperative delirium. In the present study, we investigated levels of neopterin, interleukin-6 (IL-6) and insulin-like growth factor-1 (IGF-1) in acutely ill admitted elderly patients with and without a delirium.

METHODS

Plasma/serum levels of neopterin, IL-6 and IGF-1 were determined in patients aged ≥65 years admitted to the wards of Internal Medicine and Geriatrics. Differences in biomarker levels between patients with and without a delirium were investigated by the analysis of variance in models adjusted for age, gender, comorbidities and eGFR (when appropriate).

RESULTS

Eighty-six patients were included; 23 of them with a delirium. In adjusted models, higher mean levels of neopterin (70.5 vs. 45.9 nmol/l, p = 0.009) and IL-6 (43.1 vs. 18.5 pg/ml, p = 0.034) and lower mean levels of IGF-1 (6.3 vs. 9.3 nmol/l, p = 0.007) were found in patients with a delirium compared to those without.

CONCLUSIONS

The findings of this study suggest that neopterin might be a potential biomarker for delirium which, through oxidative stress and activation of the immune system, may play a role in the pathophysiology of delirium.

Postoperative Delirium in the Geriatric Patient

Postoperative delirium, a common complication in older surgical patients, is independently associated with increased morbidity and mortality. Patients older than 65 years receive greater than one-third of the more than 40 million anesthetics delivered yearly in the United States. This number is expected to increase with the aging of the population. Thus, it is increasingly important that perioperative clinicians who care for geriatric patients have an understanding of the complex syndrome of postoperative delirium.

A Case Report on Varenicline Induced Delirium in an Alcohol and Nicotine Dependent Patient

Varenicline is a smoking cessation agent. Varenicline acts as a partial agonist of α4β2 neuronal nicotinic acetylcholine receptor and prevents nicotine binding to the same. It also causes dopamine (DA) stimulation that decreases craving and symptoms of dependence. A 40-year-old male diagnosed with alcohol and nicotine dependence syndrome was treated with 1 mg of varenicline for 3 days. Patient developed episodes of transient delirium within 15-30 min after administration of varenicline. Patient was disoriented and did not respond relevantly. Patient would have disorientation and would respond irrelevantly and was unable to recall the event completely. There were no features suggestive of seizures. The episodes resolved after the medication was stopped. Varenicline, with its partial agonistic effect on nicotinergic receptors, stimulates the release of multiple neurotransmitters including DA. DA dysregulation is probably responsible for the development of neuropsychiatric adverse reactions due to varenicline. This is the first case report to the best of our knowledge reporting varenicline induced dilirium. In this case, the adverse event was found in an alcohol and nicotine dependent patient undergoing treatment. It is essential to monitor uncommon adverse effects as this can cause significant morbidity.

Smoking increases the risk of delirium for older inpatients: a prospective population-based study

OBJECTIVES

To investigate the association between smoking in the older population and the risk of inpatient delirium, which is common and has adverse consequences.

METHOD

Participants (N=3754) were insurants aged ≥55years of the largest German statutory health insurance company, who enrolled in a 6-year prospective population-based study. Baseline smoking, adjusted for age, sex, depressive symptoms, cognitive impairment and alcohol consumption, was analyzed as risk factor of inpatient delirium. Results are presented as hazard ratios (HRs) and 95% confidence intervals (95% CIs).

RESULTS

Three-hundred seventy-three (10.0%) participants were smokers at baseline, 865 (23.0%) were quitters and 2516 (67.0%) were lifelong abstainers. Mean pack-years of smokers and quitters were 23.8 (S.D.=22.4). Sixty-one (1.6%) received a diagnosis of inpatient delirium. Smokers had an increased risk of delirium compared to abstainers in the fully adjusted model (HR=2.87, 95% CI 1.24-6.66). Quitters and abstainers did not differ (HR=0.79, 95% CI 0.37-1.72). Comparing smokers and quitters, current smoking status (HR=3.22, 95% CI 1.20-8.62) but not pack-years [residual χ(2)(1)=0.25, P=.874] were associated with inpatient delirium.

CONCLUSION

Only current smoking but not being a quitter and the lifetime amount smoked were associated with inpatient delirium, indicating that acute nicotine withdrawal may represent a relevant pathogenic mechanism.

The interface between delirium and dementia in elderly adults

Delirium and dementia are two of the most common causes of cognitive impairment in older populations, yet their interrelation remains poorly understood. Previous studies have shown that dementia is the leading risk factor for delirium and that delirium is an independent risk factor for subsequent development of dementia. However, a major area of controversy is whether delirium is simply a marker of vulnerability to dementia, whether the effect of delirium is solely related to its precipitating factors, or whether delirium itself can cause permanent neuronal damage and lead to dementia. Ultimately, all of these hypotheses are likely to be true. Emerging evidence from epidemiological, clinicopathological, neuroimaging, biomarker, and experimental studies lends support to a strong relation between delirium and dementia, and to both shared and distinct pathological mechanisms. New preventive and therapeutic approaches that target delirium might offer a sought-after opportunity for early intervention, preservation of cognitive reserve, and prevention of irreversible cognitive decline in ageing.

Biomarkers of postoperative delirium and cognitive dysfunction

Elderly surgical patients frequently experience postoperative delirium (POD) and the subsequent development of postoperative cognitive dysfunction (POCD). Clinical features include deterioration in cognition, disturbance in attention and reduced awareness of the environment and result in higher morbidity, mortality and greater utilization of social financial assistance. The aging Western societies can expect an increase in the incidence of POD and POCD. The underlying pathophysiological mechanisms have been studied on the molecular level albeit with unsatisfying small research efforts given their societal burden. Here, we review the known physiological and immunological changes and genetic risk factors, identify candidates for further studies and integrate the information into a draft network for exploration on a systems level. The pathogenesis of these postoperative cognitive impairments is multifactorial; application of integrated systems biology has the potential to reconstruct the underlying network of molecular mechanisms and help in the identification of prognostic and diagnostic biomarkers.