Systemic infection and delirium: when cytokines and acetylcholine collide

Ginsenoside Rg1 protects against sepsis-associated encephalopathy through beclin 1-independent autophagy in mice

BACKGROUND

Sepsis-associated encephalopathy (SAE), a commonly complicated syndrome, is associated with increased mortality in patients with sepsis. Currently, no specific diagnostic test or effective intervention exists to improve long-term consequences on cerebral function. Ginsenoside Rg1 (Rg1), a major component in ginseng, was reported to have pleiotropic properties including anti-inflammation and neuroprotection. The aim of our study was to investigate the protective effect of Rg1 on SAE and the potential mechanism.

MATERIALS AND METHODS

SAE model was prepared by inducing cecal ligation and puncture (CLP) in mice. Rg1 was injected 1 h before the CLP operation. Survival rate within 7 d after operation was analyzed. Surviving mice were subjected to Morris water maze tests and the brains were collected for histopathologic evaluation and immunohistochemistry. The hippocampus was obtained for Western blot, real time polymerase chain reaction, and enzyme-linked immunosorbent assay analysis.

RESULTS

Rg1 improved the postoperative survival rate and protected against sepsis-associated learning and memory impairments (Morris water maze). Besides, Rg1 was able to attenuate brain histopathologic changes (hematoxylin and eosin staining), suppress Iba1 activation, decrease the expressions of inflammatory cytokines (tumor necrosis factor α, interleukin 1β, and interleukin 6), and reduce neuronal apoptosis (cleaved caspase 3 activation) in hippocampus. Furthermore, the mechanism study showed that Rg1 suppressed the expressions of light chain 3-II and p62 in hippocampus but not beclin 1.

CONCLUSIONS

These findings suggested that Rg1 improved the survival rate and ameliorated cognitive impairments partially through regulating cerebral inflammation and apoptosis. In addition, the action mechanism might be noncanonical beclin 1-independent autophagy pathway. Rg1 may be a promising treatment strategy for SAE.

Microglial Priming and Alzheimer's Disease: A Possible Role for (Early) Immune Challenges and Epigenetics?

Neuroinflammation is thought to contribute to Alzheimer's disease (AD) pathogenesis that is, to a large extent, mediated by microglia. Given the tight interaction between the immune system and the brain, peripheral immune challenges can profoundly affect brain function. Indeed, both preclinical and clinical studies have indicated that an aberrant inflammatory response can elicit behavioral impairments and cognitive deficits, especially when the brain is in a vulnerable state, e.g., during early development, as a result of aging, or under disease conditions like AD. However, how exactly peripheral immune challenges affect brain function and whether this is mediated by aberrant microglial functioning remains largely elusive. In this review, we hypothesize that: (1) systemic immune challenges occurring during vulnerable periods of life can increase the propensity to induce later cognitive dysfunction and accelerate AD pathology; and (2) that "priming" of microglial cells is instrumental in mediating this vulnerability. We highlight how microglia can be primed by both neonatal infections as well as by aging, two periods of life during which microglial activity is known to be specifically upregulated. Lasting changes in (the ratios of) specific microglial phenotypes can result in an exaggerated pro-inflammatory cytokine response to subsequent inflammatory challenges. While the resulting changes in brain function are initially transient, a continued and/or excess release of such pro-inflammatory cytokines can activate various downstream cellular cascades known to be relevant for AD. Finally, we discuss microglial priming and the aberrant microglial response as potential target for treatment strategies for AD.

Delirium in older adults: a chronic cognitive disorder?

Delirium is defined as a neurocognitive disorder characterized by sudden onset, fluctuating course, and disturbances in level of consciousness, attention, orientation, memory, thought, perception, and behavior (American Psychiatric Association, 2013). It occurs in hyperactive, hypoactive, or mixed forms in up to 50% of older hospital patients (Inouye et al., 2014) and 70% of older long-term care residents (McCusker et al., 2011), many with pre-existing dementia (Fick et al., 2002).

Severe Infections are Common in Thiamine Deficiency and May be Related to Cognitive Outcomes: A Cohort Study of 68 Patients With Wernicke-Korsakoff Syndrome

BACKGROUND

Wernicke encephalopathy can have different clinical outcomes. Although infections may precipitate the encephalopathy itself, it is unknown whether infections also modify the long-term outcome in patients developing Korsakoff syndrome.

OBJECTIVE

To determine whether markers of infection, such as white blood cell (WBC) counts and absolute neutrophil counts in the Wernicke phase, are associated with cognitive outcomes in the end-stage Korsakoff syndrome.

METHOD

Retrospective, descriptive study of patients admitted to Slingedael Korsakoff Center, Rotterdam, The Netherlands. Hospital discharge letters of patients with Wernicke encephalopathy were searched for relevant data on infections present upon hospital admission. Patients were selected for further analysis if data were available on WBC counts in the Wernicke phase and at least 1 of 6 predefined neuropsychological tests on follow-up.

RESULTS

Infections were reported in 35 of 68 patients during the acute phase of Wernicke-Korsakoff syndrome-meningitis (1), pneumonia (14), urinary tract infections (9), acute abdominal infections (4), sepsis (5) empyema, (1) and infection "of unknown origin" (4). The neuropsychological test results showed significant lower scores on the Cambridge Cognitive Examination nonmemory section with increasing white blood cell counts (Spearman rank correlation, ρ = -0.34; 95% CI: -0.57 to -0.06; 44 patients) and on the "key search test" of the behavioral assessment of the dysexecutive syndrome with increasing absolute neutrophil counts (ρ= -0.85; 95% CI: -0.97 to -0.42; 9 patients).

CONCLUSIONS

Infections may be the presenting manifestation of thiamine deficiency. Patients with Wernicke-Korsakoff syndrome who suffered from an infection during the acute phase are at risk of worse neuropsychological outcomes on follow-up.

Frequency of full, partial and no recovery from subsyndromal deliriumin older hospital inpatients

OBJECTIVES

To determine the frequencies of full, partial and no recovery from subsyndromal delirium (SSD) in older hospital inpatients. A secondary objective was to compare the recovery status of patients with SSD or delirium.

METHODS

SSD was defined as acute onset of one or more Confusion Assessment Method core symptoms of delirium (fluctuation, inattention, disorganized thinking and altered level of consciousness) not meeting criteria for delirium and not progressing to delirium. The recovery status of medical or surgical inpatients aged 65 and older with SSD was assessed approximately 1 and 3 months after enrolment. Primary outcome categories were full recovery (no core symptoms of delirium), partial recovery (presence of one or more core symptoms but fewer symptoms than at enrolment), no recovery (same number of core symptoms as at enrolment) or death. Nominal logistic regression was used to compare the recovery status of patients with SSD or delirium.

RESULTS

Twenty-eight patients with SSD were enrolled. At the first follow-up, the frequencies of full, partial and no recovery and death were 40%, 12%, 32% and 16%, respectively; at the second follow-up, the frequencies were 54%, 8%, 21% and 17%, respectively. The frequency of full recovery was much higher in patients with SSD than delirium.

CONCLUSION

Small study sample size notwithstanding, the majority (54%) of patients with SSD recovered fully, but a substantial proportion (29%) had a protracted course. It may be important to monitor the longer-term course of SSD and develop strategies to ensure full recovery in all patients.

"I Can Remember Sort of Vivid People…but to Me They Were Plasticine." Delusions on the Intensive Care Unit: What Do Patients Think Is Going On?

INTRODUCTION

Patients who develop intensive care unit (ICU) acquired delirium stay longer in the ICU, and hospital, and are at risk of long-term mental and physical health problems. Despite guidelines for patient assessment, risk limitation, and treatment in the ICU population, delirium and associated delusions remain a relatively common occurrence on the ICU. There is considerable information in the literature describing the incidence, suspected causes of, and discussion of the benefits and side-effects of the various treatments for delirium in the ICU. But peer-reviewed patient-focused research is almost non-existent. There is therefore a very limited understanding of the reality of delusions in the intensive care unit from the patient's point of view.

METHOD

A secondary analysis of the original interviews conducted by the University of Oxford Health Experiences Research Group was undertaken to explore themes relating specifically to sleep and delirium.

RESULTS

Patients describe a liminal existence on the ICU. On the threshold of consciousness their reality is uncertain and their sense of self is exposed. Lack of autonomy in an unfamiliar environment prompts patients to develop explanations and understandings for themselves with no foothold in fact.

CONCLUSION

Patients on the ICU are perhaps more disoriented than they appear and early psychological intervention in the form of repeated orientation whilst in the ICU might improve the patient experience and defend against development of side-effects.

Statins and delirium during critical illness: a multicenter, prospective cohort study

OBJECTIVE

Since statins have pleiotropic effects on inflammation and coagulation that may interrupt delirium pathogenesis, we tested the hypotheses that statin exposure is associated with reduced delirium during critical illness, whereas discontinuation of statin therapy is associated with increased delirium.

DESIGN

Multicenter, prospective cohort study.

SETTING

Medical and surgical ICUs in two large tertiary care hospitals in the United States.

PATIENTS

Patients with acute respiratory failure or shock.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We measured statin exposure prior to hospitalization and daily during the ICU stay, and we assessed patients for delirium twice daily using the Confusion Assessment Method for the ICU. Of 763 patients included, whose median (interquartile range) age was 61 years (51-70 yr) and Acute Physiology and Chronic Health Evaluation II was 25 (19-31), 257 (34%) were prehospital statin users and 197 (26%) were ICU statin users. Overall, delirium developed in 588 patients (77%). After adjusting for covariates, ICU statin use was associated with reduced delirium (p < 0.01). This association was modified by sepsis and study day; for example, statin use was associated with reduced delirium among patients with sepsis on study day 1 (odds ratio, 0.22; 95% CI, 0.10-0.49) but not among patients without sepsis on day 1 (odds ratio, 0.92; 95% CI, 0.46-1.84) or among those with sepsis later, for example, on day 13 (odds ratio, 0.70; 95% CI, 0.35-1.41). Prehospital statin use was not associated with delirium (odds ratio, 0.86; 95% CI, 0.44-1.66; p = 0.18), yet the longer a prehospital statin user's statin was held in the ICU, the higher the odds of delirium (overall p < 0.001 with the odds ratio depending on sepsis status and study day due to significant interactions).

CONCLUSIONS

In critically ill patients, ICU statin use was associated with reduced delirium, especially early during sepsis; discontinuation of a previously used statin was associated with increased delirium.

Effects of Intraoperative Hemodynamics on Incidence of Postoperative Delirium in Elderly Patients: A Retrospective Study

BACKGROUND

Postoperative delirium (POD) is a common complication in the elderly. This retrospective study investigated the effect of intraoperative hemodynamics on the incidence of POD in elderly patients after major surgery to explore ways to reduce the incidence of POD.

MATERIAL/METHODS

Based on the incidence of POD, elderly patients (81±6 y) were assigned to a POD (n=137) or non-POD group (n=343) after elective surgery with total intravenous anesthesia. POD was diagnosed based on the guidelines of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), using the confusion assessment method. The hemodynamic parameters, such as mean arterial pressure, were monitored 10 min before anesthesia (baseline) and intraoperatively. The incidence of intraoperative hypertension, hypotension, tachycardia, and bradycardia were calculated.

RESULTS

At 30 min and 60 min after the initiation of anesthesia and at the conclusion of surgery, the monitored hemodynamic parameter values of the POD group, but not those of the non-POD group, were significantly higher than at baseline. Multivariate logistic regression analysis showed that intraoperative hypertension and tachycardia were significantly associated with POD.

CONCLUSIONS

Intraoperative hypertension and tachycardia were significantly associated with POD. Maintaining intraoperative stable hemodynamics may reduce the incidence of POD in elderly patients undergoing surgery.

Comparing consultation-liaison psychiatrist's and neurologist's approaches to delirium - A retrospective analysis

OBJECTIVE

To compare the diagnostic, management, and treatment recommendations made by consultation-liaison psychiatrists (CLP) and neurologists (CLN) for suspected delirium and to investigate factors that may have influenced the choice for a particular consultation service.

METHOD

In this retrospective case analysis, we screened the files of 1882 (CLP: 1112, CLN: 770) inpatients seen by CLP and CLN at the Charité - University Medicine, Berlin, Germany, in 2013. This revealed a total of 148 (CLP: 99, CLN: 49) delirium patients. Information found on the consultation form and in the patients' files was used for data collection and subsequently analyzed.

RESULTS

Intensive care and surgical units preferably called CLP, while internists consulted more CLN and patients suffering from neurological or psychiatric preconditions were more often seen by the respective specialist. Despite no significant difference between psychomotor activity levels among the groups, CLP recommended significantly more pharmacological interventions (p = 0.000) and CLN ordered significantly more diagnostic procedures (p = 0.000).

CONCLUSION

Our results show considerable differences between CLP and CLN treatment recommendations, which may indicate a conflicting approach to delirium work-up, not accountable to unequal patient characteristics. These preliminary results are not conclusive and should be followed up by high evidence level research.

A clinical perspective of sepsis-associated delirium

The term sepsis-associated encephalopathy (SAE) has been applied to animal models, postmortem studies in patients, and severe cases of sepsis. SAE is considered to include all types of brain dysfunction, including delirium, coma, seizure, and focal neurological signs. Clinical data for sepsis-associated delirium (SAD) have been accumulating since the establishment of definitions of coma or delirium and the introduction of validated screening tools. Some preliminary studies have examined the etiology of SAD. Neuroinflammation, abnormal cerebral perfusion, and neurotransmitter imbalances are the main mechanisms underlying the development of SAD. However, there are still no specific diagnostic blood, electrophysiological, or imaging tests or treatments specific for SAD. The duration of delirium in intensive care patients is associated with long-term functional disability and cognitive impairment, although this syndrome usually reverses after the successful treatment of sepsis. Once the respiratory and hemodynamic states are stabilized, patients with severe sepsis or septic shock should receive rehabilitation as soon as possible because early initiation of rehabilitation can reduce the duration of delirium. We expect to see further pathophysiological data and the development of novel treatments for SAD now that reliable and consistent definitions of SAD have been established.

Association of serum brain-derived neurotrophic factor (BDNF) and tumor necrosis factor-alpha (TNF-α) with diagnosis of delirium in oncology inpatients

OBJECTIVE

To evaluate brain-derived neurotrophic factor (BDNF) and tumor necrosis factor-α (TNF-α) blood levels as disease biomarkers of delirium in oncology inpatients.

METHODS

Seventeen oncology inpatients with delirium, 28 oncology inpatients without delirium, and 25 non-oncology controls (caregivers) were consecutively recruited from a Brazilian cancer center. This sample was matched by age, sex, and education level. The Confusion Assessment Method, the Mini-Mental State Examination, and the Digit Span Test were administered to ascertain delirium diagnosis. BDNF and TNF-α levels were measured by the Sandwich-ELISA method and flow cytometry, respectively. Blood samples were collected immediately after clinical evaluation.

RESULTS

Oncology inpatients (with and without delirium) showed significantly lower BDNF levels compared with non-oncology controls (F = 13.830; p = 0.001). TNF-α levels did not differ between the three groups.

CONCLUSION

A cross-sectional relationship of BDNF and TNF-α blood levels with delirium in oncology inpatients was not demonstrated. The association between cancer and reduced serum BDNF levels may be mediated by confounding factors.

Influence of Granulocyte-Macrophage Colony-Stimulating Factor or Influenza Vaccination on HLA-DR, Infection and Delirium Days in Immunosuppressed Surgical Patients: Double Blind, Randomised Controlled Trial

PURPOSE

Surgical patients are at high risk for developing infectious complications and postoperative delirium. Prolonged infections and delirium result in worse outcome. Granulocyte-macrophage colony-stimulating factor (GM-CSF) and influenza vaccination are known to increase HLA-DR on monocytes and improve immune reactivity. This study aimed to investigate whether GM-CSF or vaccination reverses monocyte deactivation. Secondary aims were whether it decreases infection and delirium days after esophageal or pancreatic resection over time.

METHODS

In this prospective, randomized, placebo-controlled, double-blind, double dummy trial setting on an interdisciplinary ICU of a university hospital 61 patients with immunosuppression (monocytic HLA-DR [mHLA-DR] <10,000 monoclonal antibodies [mAb] per cell) on the first day after esophageal or pancreatic resection were treated with either GM-CSF (250 μg/m2/d), influenza vaccination (Mutagrip 0.5 ml/d) or placebo for a maximum of 3 consecutive days if mHLA-DR remained below 10,000 mAb per cell. HLA-DR on monocytes was measured daily until day 5 after surgery. Infections and delirium were followed up for 9 days after surgery. Primary outcome was HLA-DR on monocytes, and secondary outcomes were duration of infection and delirium.

RESULTS

mHLA-DR was significantly increased compared to placebo (p < 0.001) and influenza vaccination (p < 0.001) on the second postoperative day. Compared with placebo, GM-CSF-treated patients revealed shorter duration of infection (p < 0.001); the duration of delirium was increased after vaccination (p = 0.003).

CONCLUSION

Treatment with GM-CSF in patients with postoperative immune suppression was safe and effective in restoring monocytic immune competence. Furthermore, therapy with GM-CSF reduced duration of infection in immune compromised patients. However, influenza vaccination increased duration of delirium after major surgery.

TRIAL REGISTRATION

www.controlled-trials.com ISRCTN27114642.

Mechanisms of long-term cognitive dysfunction of sepsis: from blood-borne leukocytes to glial cells

Several mechanisms are associated with brain dysfunction during sepsis; one of the most important are activation of microglia and astrocytes. Activation of glial cells induces changes in permeability of the blood-brain barrier, secretion of inflammatory cytokines, and these alterations could induce neuronal dysfunction. Furthermore, blood-borne leukocytes can also reach the brain and participate in inflammatory response. Mechanisms involved in sepsis-associated brain dysfunction were revised here, focusing in neuroinflammation and involvement of blood-borne leukocytes and glial cells in this process.

Observational, longitudinal study of delirium in consecutive unselected acute medical admissions: age-specific rates and associated factors, mortality and re-admission

OBJECTIVES

We aimed to determine age-specific rates of delirium and associated factors in acute medicine, and the impact of delirium on mortality and re-admission on long-term follow-up.

DESIGN

Observational study. Consecutive patients over two 8-week periods (2010, 2012) were screened for delirium on admission, using the confusion assessment method (CAM), and reviewed daily thereafter. Delirium diagnosis was made using the Diagnostic and Statistical Manual Fourth Edition (DSM IV) criteria. For patients aged ≥65 years, potentially important covariables identified in previous studies were collected with follow-up for death and re-admission until January 2014.

PARTICIPANTS

503 consecutive patients (age median=72, range 16-99 years, 236 (48%) male).

SETTING

Acute general medicine.

RESULTS

Delirium occurred in 101/503 (20%) (71 on admission, 30 during admission, 17 both), with risk increasing from 3% (6/195) at <65 years to 14% (10/74) for 65-74 years and 36% (85/234) at ≥75 years (p<0.0001). Among 308 patients aged >65 years, after adjustment for age, delirium was associated with previous falls (OR=2.47, 95% CI 1.45 to 4.22, p=0.001), prior dementia (2.08, 1.10 to 3.93, p=0.024), dependency (2.58, 1.48 to 4.48, p=0.001), low cognitive score (5.00, 2.50 to 9.99, p<0.0001), dehydration (3.53, 1.91 to 6.53, p<0.0001), severe illness (1.98, 1.17 to 3.38, p=0.011), pressure sore risk (5.56, 2.60 to 11.88, p<0.0001) and infection (4.88, 2.85 to 8.36, p<0.0001). Patients with delirium were more likely to fall (OR=4.55, 1.47 to 14.05, p=0.008), be incontinent of urine (3.76, 2.15 to 6.58, p<0.0001) or faeces (3.49, 1.81-6.73, p=0.0002) and be catheterised (5.08, 2.44 to 10.54, p<0.0001); and delirium was associated with stay >7 days (2.82, 1.68 to 4.75, p<0.0001), death (4.56, 1.71 to 12.17, p=0.003) and an increase in dependency among survivors (2.56, 1.37 to 4.76, p=0.003) with excess mortality still evident at 2-year follow-up. Patients with delirium had fewer re-admissions within 30-days (OR=0.32, 95% CI 0.09 to 1.1, p=0.07) and in total (median, IQR total re-admissions=0, 0-1 vs 1, 0-2, p=0.01).

CONCLUSIONS

Delirium affected a fifth of acute medical admissions and a third of those aged ≥75 years, and was associated with increased mortality, institutionalisation and dependency, but not with increased risk of re-admission on follow-up.

Partial and No Recovery from Delirium in Older Hospitalized Adults: Frequency and Baseline Risk Factors

OBJECTIVES

To determine the frequency and baseline risk factors for partial and no recovery from delirium in older hospitalized adults.

DESIGN

Cohort study with assessment of recovery status approximately 1 and 3 months after enrollment.

SETTING

University-affiliated, primary, acute-care hospital.

PARTICIPANTS

Medical or surgical inpatients aged 65 and older with delirium (N = 278).

MEASUREMENTS

The Mini-Mental State Examination (MMSE), Confusion Assessment Method (CAM), Delirium Index (DI), and activities of daily living (ADLs) were completed at enrollment and each follow-up. Primary outcome categories were full recovery (absence of CAM core symptoms of delirium), partial recovery (presence of ≥1 CAM core symptoms but not meeting criteria for delirium), no recovery (met CAM criteria for delirium), or death. Secondary outcomes were changes in MMSE, DI, and ADL scores between the baseline and last assessment. Potential risk factors included many clinical and laboratory variables.

RESULTS

In participants with dementia, frequencies of full, partial, and no recovery and death at first follow-up were 6.3%, 11.3%, 74.6%, and 7.7%, respectively; in participants without dementia, frequencies were 14.3%, 17%, 50.9%, and 17.9%, respectively. In participants with dementia, frequencies at the second follow-up were 7.9%, 15.1%, 57.6%, and 19.4%, respectively; in participants without dementia, frequencies were 19.2%, 20.2%, 31.7%, and 28.8%, respectively. Frequencies were similar in participants with prevalent and incident delirium and in medical and surgical participants. The DI, MMSE, and ADL scores of many participants with partial and no recovery improved. Independent baseline risk factors for delirium persistence were chart diagnosis of dementia (odds ratio (OR) = 2.51, 95% confidence interval (CI) =1.38, 4.56), presence of any malignancy (OR = 5.79, 95% CI = 1.51, 22.19), and greater severity of delirium (OR =9.39, 95% CI = 3.95, 22.35).

CONCLUSION

Delirium in many older hospitalized adults appears to be much more protracted than previously thought, especially in those with dementia, although delirium symptoms, cognition, and function improved in many participants with partial and no recovery. It may be important to monitor the longer-term course of delirium in older hospitalized adults and develop strategies to ensure full recovery.

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.

Delirium symptoms during hospitalization predict long-term mortality in patients with severe pneumonia

INTRODUCTION

Delirium is common in critically ill patients and impact in-hospital mortality in patients with pneumonia. The aim of the study was to evaluate the prevalence of delirium symptoms during hospitalization in patients with severe pneumonia and their impact on one-year mortality.

METHODS

This was an observational, retrospective, cohort study of consecutive patients admitted to the respiratory high dependency unit of the San Gerardo University Hospital, Monza, Italy, between January 2009 and December 2012 with a diagnosis of severe pneumonia. A search through the charts looking for ten key words associated with delirium (confusion, disorientation, altered mental status, delirium, agitation, inappropriate behavior, mental status change, inattention, hallucination, lethargy) was performed by a multidisciplinary team. The primary endpoint was mortality at one-year follow-up. Secondary endpoint was in-hospital mortality.

RESULTS

A total of 172 patients were enrolled (78 % males; median age 75 years). At least one delirium symptom was detected in 53 patients (31 %) during hospitalization. The prevalence of delirium symptoms was higher among those who died during hospitalization vs. those who survived (44 vs. 27 %, p = 0.049, respectively). Seventy-one patients (46 %) died during the one-year follow-up. The prevalence of at least one delirium symptom was higher among those who died than those who survived during the one-year follow-up (39 vs. 21 %, p = 0.014, respectively). At the multivariable logistic regression analysis, after adjustment for age, comorbidities and severe sepsis, the presence of at least one delirium symptom during hospitalization was an independent predictor of one-year mortality (OR 2.35; 95 % CI 1.13-4.90; p = 0.023).

CONCLUSIONS

Delirium symptoms are independent predictors of one-year mortality in hospitalized patients with severe pneumonia. Further studies should confirm our results using prospective methods of collecting data.

Understanding and reducing disability in older adults following critical illness

OBJECTIVE

To review how disability can develop in older adults with critical illness and to explore ways to reduce long-term disability following critical illness.

DATA SOURCES

We searched PubMed, CINAHL, Web of Science and Google Scholar for studies reporting disability outcomes (i.e., activities of daily living, instrumental activities of daily living, and mobility activities) and/or cognitive outcomes among patients treated in an ICU who were 65 years or older. We also reviewed the bibliographies of relevant citations to identify additional citations.

STUDY SELECTION

We identified 19 studies evaluating disability outcomes in critically ill patients who were 65 years and older.

DATA EXTRACTION

Descriptive epidemiologic data on disability after critical illness.

DATA SYNTHESIS

Newly acquired disability in activities of daily living, instrumental activities of daily living, and mobility activities was commonplace among older adults who survived a critical illness. Incident dementia and less severe cognitive impairment were also highly prevalent. Factors related to the acute critical illness, ICU practices, such as heavy sedation, physical restraints, and immobility, as well as aging physiology, and coexisting geriatric conditions can combine to result in these poor outcomes.

CONCLUSIONS

Older adults who survive critical illness have physical and cognitive declines resulting in disability at greater rates than hospitalized, noncritically ill and community dwelling older adults. Interventions derived from widely available geriatric care models in use outside of the ICU, which address modifiable risk factors including immobility and delirium, are associated with improved functional and cognitive outcomes and can be used to complement ICU-focused models such as the ABCDEs.

Inhibition of JAK2 attenuates the increase in inflammatory markers in microglia from APP/PS1 mice

There is a wealth of evidence indicating that macrophages adopt distinct phenotypes when exposed to specific stimuli and, in the past few years, accumulating data suggest that microglia behave somewhat similarly. Therefore, microglia can adopt the so-called M1 or M2 phenotypes in response to interferon-γ (IFNγ) and interleukin-4, respectively. Although it has yet to be unequivocally proven in the context of microglia, acutely activated M1 cells are probably protective, although a persistent M1 state is likely to be damaging, whereas M2 cells may be reparative and restorative. In this case, particularly because the current evidence suggests the development of a predominantly M1 state with age and in neurodegenerative diseases, it is important to identify mechanisms by which polarization of microglia can be modulated. The present findings indicate that exposure of cultured microglia to IFNγ increased expressions of the archetypal markers of the M1 phenotype, tumour necrosis factor-α, and inducible nitric oxide synthase, and preexposure of cells to amyloid-β (Aβ) sensitized microglia to subsequent stimulation with IFNγ. Importantly, this synergy was also evident in microglia prepared from the brains of transgenic mice that overexpress amyloid precursor protein (APP) and presenilin 1 (PS1, APP/PS1 mice) and are exposed to a combination of increasing concentrations of endogenous Aβ from 4 or 5 months of age and an age-related increase in IFNγ. Significantly, the JAK2 inhibitor, TG101209, attenuated the IFNγ-induced changes in cultured microglia and in isolated microglia prepared from APP/PS1 mice. These findings suggest that targeting JAK2 may be a potential strategy for reducing neuroinflammation in Alzheimer's disease.

Severe, Persistent and Fatal Delirium in Psychogeriatric Patients Admitted to a Psychiatric Hospital

BACKGROUND/AIMS

Although delirium is generally regarded as a transient syndrome, persistence of delirium in patients with cognitive impairment - even with fatal outcome - has been reported as well. This study aims to describe the clinical features and neuropathological correlates of this type of delirium.

METHODS

Inclusion criteria for this case series were: (1) severe persistent delirium until death, (2) history of cognitive decline and (3) consent for brain autopsy. Medical records were examined in combination with collected clinical data and neuropathological findings.

RESULT

In 15 patients, all living at home before admission, episodes with delirium lasted for 4.2 months on average. No distinct medical causes of persistent delirium could be identified. Pathological diagnoses included Alzheimer's disease and dementia with Lewy bodies as well as single cases of Creutzfeldt-Jakob disease and progressive supranuclear palsy.

CONCLUSION

Severe, persistent and fatal delirium in patients with cognitive impairment can occur relatively early in the disease trajectory and is associated with diverse neuropathologies.

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.

Systemic inflammation and microglial activation: systematic review of animal experiments

Background

Animal studies show that peripheral inflammatory stimuli may activate microglial cells in the brain implicating an important role for microglia in sepsis-associated delirium. We systematically reviewed animal experiments related to the effects of systemic inflammation on the microglial and inflammatory response in the brain.

Methods

We searched PubMed between January 1, 1950 and December 1, 2013 and Embase between January 1, 1988 and December 1, 2013 for animal studies on the influence of peripheral inflammatory stimuli on microglia and the brain. Identified studies were systematically scored on methodological quality. Two investigators extracted independently data on animal species, gender, age, and genetic background; number of animals; infectious stimulus; microglial cells; and other inflammatory parameters in the brain, including methods, time points after inoculation, and brain regions.

Results

Fifty-one studies were identified of which the majority was performed in mice (n = 30) or in rats (n = 19). Lipopolysaccharide (LPS) (dose ranging between 0.33 and 200 mg/kg) was used as a peripheral infectious stimulus in 39 studies (76 %), and live or heat-killed pathogens were used in 12 studies (24 %). Information about animal characteristics such as species, strain, sex, age, and weight were defined in 41 studies (80 %), and complete methods of the disease model were described in 35 studies (68 %). Studies were also heterogeneous with respect to methods used to assess microglial activation; markers used mostly were the ionized calcium binding adaptor molecule-1 (Iba-1), cluster of differentiation 68 (CD68), and CD11b. After LPS challenge microglial activation was seen 6 h after challenge and remained present for at least 3 days. Live Escherichia coli resulted in microglial activation after 2 days, and heat-killed bacteria after 2 weeks. Concomitant with microglial response, inflammatory parameters in the brain were reviewed in 23 of 51 studies (45 %). Microglial activation was associated with an increase in Toll-like receptor (TLR-2 and TLR-4), tumor necrosis factor alpha (TNF-α), and interleukin 1 beta (IL-1β) messenger ribonucleic acid (mRNA) expression or protein levels.

Interpretation

Animal experiments robustly showed that peripheral inflammatory stimuli cause microglial activation. We observed distinct differences in microglial activation between systemic stimulation with (supranatural doses) LPS and live or heat-killed bacteria.

Complement component C3 and butyrylcholinesterase activity are associated with neurodegeneration and clinical disability in multiple sclerosis

Dysregulation of the complement system is evident in many CNS diseases but mechanisms regulating complement activation in the CNS remain unclear. In a recent large rat genome-wide expression profiling and linkage analysis we found co-regulation of complement C3 immediately downstream of butyrylcholinesterase (BuChE), an enzyme hydrolyzing acetylcholine (ACh), a classical neurotransmitter with immunoregulatory effects. We here determined levels of neurofilament-light (NFL), a marker for ongoing nerve injury, C3 and activity of the two main ACh hydrolyzing enzymes, acetylcholinesterase (AChE) and BuChE, in cerebrospinal fluid (CSF) from patients with MS (n = 48) and non-inflammatory controls (n = 18). C3 levels were elevated in MS patients compared to controls and correlated both to disability and NFL. C3 levels were not induced by relapses, but were increased in patients with ≥9 cerebral lesions on magnetic resonance imaging and in patients with progressive disease. BuChE activity did not differ at the group level, but was correlated to both C3 and NFL levels in individual samples. In conclusion, we show that CSF C3 correlates both to a marker for ongoing nerve injury and degree of disease disability. Moreover, our results also suggest a potential link between intrathecal cholinergic activity and complement activation. These results motivate further efforts directed at elucidating the regulation and effector functions of the complement system in MS, and its relation to cholinergic tone.

Cardiac diseases complicating community-acquired pneumonia

PURPOSE OF REVIEW

The aim is to evaluate basic mechanisms, prevalence, risk factors, outcomes, and potential treatments of cardiovascular events (CVEs) in patients with community-acquired pneumonia (CAP).

RECENT FINDINGS

In this review, we present a new model to evaluate the pathophysiology of cardiac disease in patients with pneumonia based on plaque-related events, such as acute myocardial infarction, versus plaque-unrelated events, such as arrhythmias and heart failure. CAP increases the risk for both plaque-related and plaque-unrelated events with an absolute rate of CVE across different cohorts that varies broadly from 10 to 30%. These complications may happen among both ambulatory patients and inpatients, either on admission or during hospitalization, and/or after discharge. CVEs represent a major cause for increased mortality in CAP patients, contributing to more than 30% of deaths at long-term follow-up.

SUMMARY

From a clinical perspective, especially during the first 24 h after hospitalization, CAP patients should be tested for the probability to have or develop during hospitalization a cardiac event. From a research point of view, there is an urgent need to prospectively evaluate cardioprotective interventions.

The protocol of the Oslo Study of Clonidine in Elderly Patients with Delirium; LUCID: a randomised placebo-controlled trial

Background

Delirium affects 15% of hospitalised patients and is linked with poor outcomes, yet few pharmacological treatment options exist. One hypothesis is that delirium may in part result from exaggerated and/or prolonged stress responses. Dexmedetomidine, a parenterally-administered alpha2-adrenergic receptor agonist which attenuates sympathetic nervous system activity, shows promise as treatment in ICU delirium. Clonidine exhibits similar pharmacodynamic properties and can be administered orally. We therefore wish to explore possible effects of clonidine upon the duration and severity of delirium in general medical inpatients.

Methods/Design

The Oslo Study of Clonidine in Elderly Patients with Delirium (LUCID) is a randomised, placebo-controlled, double-blinded, parallel group study with 4-month prospective follow-up. We will recruit 100 older medical inpatients with delirium or subsyndromal delirium in the acute geriatric ward. Participants will be randomised to oral clonidine or placebo until delirium free for 2 days (Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria), or after a maximum of 7 days treatment. Assessment of haemodynamics (blood pressure, heart rate and electrocardiogram) and delirium will be performed daily until discharge or a maximum of 7 days after end of treatment. The primary endpoint is the trajectory of delirium over time (measured by Memorial Delirium Assessment Scale). Secondary endpoints include the duration of delirium, use of rescue medication for delirium, pharmacokinetics and pharmacodynamics of clonidine, cognitive function after 4 months, length of hospital stay and need for institutionalisation.

Discussion

LUCID will explore the efficacy and safety of clonidine for delirium in older medical inpatients.

Trial registration

ClinicalTrials.gov NCT01956604. EudraCT Number: 2013-000815-26

Recent progress in research of postoperative delirium after abdominal surgery

Postoperative delirium (POD) is a common acute cerebral syndrome after abdominal surgery, with disturbance of consciousness, cognition and attention as the main clinical manifestations, found mostly in elderly male patients. POD often increases mortality dramatically and prolongs the length of hospital stay. There are many factors responsible for the occurrence of POD, such as age, underlying diseases and antipsychotic drugs. Due to the complex onset of the disease, multicomponent intervention strategies have been recommended and proved effective. In contrast, there has been no evidence that pharmacological prevention or therapy could reduce the incidence or shorten the duration of POD. This paper reviews the recent progress in research of postoperative delirium after abdominal surgery with regards to its mechanism, risk factors, prevention and treatment.

RBC acetyl cholinesterase: A poor man's early diagnostic biomarker for familial alzheimer's and Parkinson's disease dementia

Objective:

Analysis of red blood cell acetyl cholinesterase (AChE) in a familial Alzheimer's diseases (AD) Parkinson's disease dementia (PDD) and their first generation.

Setting:

General hospital, Mahad district, Raigad.

Patients and Methods:

Clinically diagnosed patients of AD and PDD and their asymptomatic relatives. Their blood was collected in EDTA tube and transferred to laboratory at Mumbai.

Result:

Median red blood cell (RBC) cholinesterase levels amongst PDD, their first generation asymptomatic relatives, familial AD, asymptomatic relatives of AD, healthy controls, farmers exposed to pesticides (positive control) and other neurological condition without dementia (hypertension with TIA 1, sub-dural hematoma 2, hypothyroid 1, non-familial unilateral parkinsonism without dementia 3, writers cramps 2, hyponitremia 1 and cerebral palsy with non-fluent aphasia 1). Median values of RBC AChE were 19086.78 U/L, 15666.05 U/L, 9013.11 U/L, 7806.19 U/L, 14334.57 U/L, 9785.05 U/L and 13162.60 U/L, respectively. As compared to controls, RBC AChE levels were statistically significant among PDD (P = 0.004) and significantly lowered among familial AD patients (P = 0.010), relatives of patients (P = 0.010).

Interpretations:

Below the normal RBC AChE level is a potential biomarker in asymptomatic relatives of familial AD patients. RBC AChE is raised than normal level in patients suffering from PDD, where AChE inhibitors are helpful. However, RBC AChE level below the normal where AChE inhibitor may not be effective.

The association between acute respiratory distress syndrome, delirium, and in-hospital mortality in intensive care unit patients

RATIONALE

Both acute respiratory distress syndrome (ARDS) and intensive care unit (ICU) delirium are associated with significant morbidity and mortality. However, the risk of delirium and its impact on mortality in ARDS patients is unknown.

OBJECTIVES

To determine if ARDS is associated with a higher risk for delirium compared with respiratory failure without ARDS, and to determine the association between ARDS and in-hospital mortality after adjusting for delirium.

METHODS

Prospective observational cohort study of adult ICU patients admitted to two urban academic hospitals.

MEASUREMENTS AND MAIN RESULTS

Delirium was assessed daily using the Confusion Assessment Method for the ICU and Richmond Agitation and Sedation Scale. Of the 564 patients in our cohort, 48 had ARDS (9%). Intubated patients with ARDS had the highest prevalence of delirium compared with intubated patients without ARDS and nonintubated patients (73% vs. 52% vs. 21%, respectively; P < 0.001). After adjusting for common risk factors for delirium, ARDS was associated with a higher risk for delirium compared with mechanical ventilation without ARDS (odds ratio [OR], 6.55 [1.56-27.54]; P = 0.01 vs. OR, 1.98 [1.16-3.40]; P < 0.013); reference was nonintubated patients. Although ARDS was significantly associated with hospital mortality (OR, 10.44 [3.16-34.50]), the effect was largely reduced after adjusting for delirium and persistent coma (OR, 5.63 [1.55-20.45]).

CONCLUSIONS

Our findings suggest that ARDS is associated with a greater risk for ICU delirium than mechanical ventilation alone, and that the association between ARDS and in-hospital mortality is weakened after adjusting for delirium and coma. Future studies are needed to determine if prevention and reduction of delirium in ARDS patients can improve outcomes.

Cognitive decline after sepsis

The modern era of sepsis management is characterised by a growing number of patients who survive in the short term and are discharged from hospital. Increasing evidence suggests that these survivors exhibit long-term neurological sequelae, particularly substantial declines in cognitive function. The exact prevalence and outcomes of these neuropsychological sequelae are unclear. The mechanisms by which sepsis induces cognitive dysfunction probably include vascular injuries and neuroinflammation that are mediated by systemic metabolism disorders and overwhelming inflammation, a disrupted blood-brain barrier, oxidative stress, and severe microglial activation, particularly within the limbic system. Interventions targeting the blood-brain barrier, glial activation, and oxidative stress have shown promise in prevention of cognitive dysfunction in various experimental models of sepsis. The next step should be to translate these favourable effects into positive clinical results.

The attributable mortality of delirium in critically ill patients: prospective cohort study

OBJECTIVE

To determine the attributable mortality caused by delirium in critically ill patients.

DESIGN

Prospective cohort study.

SETTING

32 mixed bed intensive care unit in the Netherlands, January 2011 to July 2013.

PARTICIPANTS

1112 consecutive adults admitted to an intensive care unit for a minimum of 24 hours.

EXPOSURES

Trained observers evaluated delirium daily using a validated protocol. Logistic regression and competing risks survival analyses were used to adjust for baseline variables and a marginal structural model analysis to adjust for confounding by evolution of disease severity before the onset of delirium.

MAIN OUTCOME MEASURE

Mortality during admission to an intensive care unit.

RESULTS

Among 1112 evaluated patients, 558 (50.2%) developed at least one episode of delirium, with a median duration of 3 days (interquartile range 2-7 days). Crude mortality was 94/558 (17%) in patients with delirium compared with 40/554 (7%) in patients without delirium (P<0.001). Delirium was significantly associated with mortality in the multivariable logistic regression analysis (odds ratio 1.77, 95% confidence interval 1.15 to 2.72) and survival analysis (subdistribution hazard ratio 2.08, 95% confidence interval 1.40 to 3.09). However, the association disappeared after adjustment for time varying confounders in the marginal structural model (subdistribution hazard ratio 1.19, 95% confidence interval 0.75 to 1.89). Using this approach, only 7.2% (95% confidence interval -7.5% to 19.5%) of deaths in the intensive care unit were attributable to delirium, with an absolute mortality excess in patients with delirium of 0.9% (95% confidence interval -0.9% to 2.3%) by day 30. In post hoc analyses, however, delirium that persisted for two days or more remained associated with a 2.0% (95% confidence interval 1.2% to 2.8%) absolute mortality increase. Furthermore, competing risk analysis showed that delirium of any duration was associated with a significantly reduced rate of discharge from the intensive care unit (cause specific hazard ratio 0.65, 95% confidence interval 0.55 to 0.76).

CONCLUSIONS

Overall, delirium prolongs admission in the intensive care unit but does not cause death in critically ill patients. Future studies should focus on episodes of persistent delirium and its long term sequelae rather than on acute mortality.Trial registration Clinicaltrials.gov NCT01905033.

Delirium diagnostic and classification challenges in palliative care: subsyndromal delirium, comorbid delirium-dementia, and psychomotor subtypes

CONTEXT

Delirium often presents difficult diagnostic and classification challenges in palliative care settings.

OBJECTIVES

To review three major areas that create diagnostic and classification challenges in relation to delirium in palliative care: subsyndromal delirium (SSD), delirium in the context of comorbid dementia, and classification of psychomotor subtypes, and to identify knowledge gaps and research priorities in relation to these three areas of focus.

METHODS

We combined multidisciplinary input from delirium researchers and knowledge users at an international delirium study planning meeting and relevant PubMed literature searches as the knowledge synthesis strategy in this review.

RESULTS

We identified six (SSD), 33 (dementia), and 44 (psychomotor subtypes) articles of relevance in relation to the focus of our review. Recent literature data highlight the frequency and impact of SSD, the relevance of comorbid dementia, and the propensity for a hypoactive presentation of delirium in the palliative population. The differential diagnoses to consider are wide and include pain, fatigue, mood disturbance, psychoactive medication effects, and other causes for altered consciousness.

CONCLUSION

Challenges in the diagnosis and classification of delirium in people with advanced disease are compounded by the generalized disturbance of central nervous system function that occurs in the seriously ill, often with comorbid illness, including dementia. Further research is needed to delineate the pathophysiological and clinical associations of these presentations and thus inform therapeutic strategies. The expanding aged population and growing focus on dementia care in palliative care highlight the need to conduct this research.

Systemic inflammation, blood-brain barrier vulnerability and cognitive/non-cognitive symptoms in Alzheimer disease: relevance to pathogenesis and therapy

The incidence of dementia is increasing at an alarming rate, and has become a major public health concern. Alzheimer disease (AD) is the most common form of dementia and is characterized by progressive cognitive impairment. In addition to classical neuropathological features such as amyloid plaques and neurofibrillary tangles (NFT), accumulation of activated immune cells has been documented in the AD brain, suggesting a contribution of neuroinflammation in the pathogenesis of AD. Besides cognitive deterioration, non-cognitive symptoms, such as agitation, aggression, depression and psychosis, are often observed in demented patients, including those with AD, and these neuropsychological symptoms place a heavy burden on caregivers. These symptoms often exhibit sudden onset and tend to fluctuate over time, and in many cases, they are triggered by an infection in peripheral organs, suggesting that inflammation plays an important role in the pathogenesis of these non-cognitive symptoms. However, there is no mechanistic explanation for the relationship between inflammation and neuropsychiatric symptoms. Observations from experimental mouse models indicate that alteration of brain blood vessels, especially blood-brain barrier (BBB) dysfunction, may contribute to the relationship. The current review summarizes the results from recent studies on the relationship between inflammation and AD, while focusing on cerebrovascular alterations, which might provide an insight into the pathogenesis of cognitive/non-cognitive symptoms in AD patients and suggest a basis for the development of new therapeutic treatments for these conditions.

Preoperative plasma leptin levels predict delirium in elderly patients after hip fracture surgery

Leptin is considered to be a modulator of the immune response. Hypoleptinemia increases the risk for Alzheimer's disease and vascular dementia. The present study aimed to investigate the ability of plasma leptin level to predict delirium in elderly patients after hip fracture surgery. Postoperative delirium (pod) was evaluated using the Confusion Assessment Method. Prolonged postoperative delirium (ppod) was defined as delirium lasting more than 4 weeks. Plasma leptin levels of 186 elderly patients and 186 elderly controls were measured by an enzyme-linked immunosorbent assay. Plasma leptin level was substantially lower in patients than in controls (4.6±2.2ng/ml vs. 7.5±1.8ng/ml, P<0.001). It was identified as an independent predictor for pod [odds ratio, 0.385; 95% confidence interval (CI), 0.286-0.517; P<0.001] and ppod (odds ratio, 0.283; 95% CI, 0.152-0.527; P<0.001) using a multivariate analysis, and had high area under receiver operating characteristic curve for pod [area under curve (AUC), 0.850; 95% CI, 0.790-0.898] and ppod (AUC, 0.890; 95% CI, 0.836-0.931). The predictive value of leptin was markedly bigger than that of age for pod (AUC, 0.705; 95% CI, 0.634-0.770; P=0.002) and ppod (AUC, 0.713; 95% CI, 0.642-0.777; P=0.019). In a combined logistic-regression model, leptin improved the AUC of age to 0.890 (95% CI, 0.836-0.931) (P<0.001) for pod and 0.910 (95% CI, 0.860-0.947) (P=0.005) for ppod. Thus, preoperative plasma leptin level may be a useful, complementary tool to predict delirium and also prolonged delirium in elderly patients after hip fracture surgery.

Thinking outside the brain for cognitive improvement: Is peripheral immunomodulation on the way?

Cognitive impairment is a devastating condition commonly observed with normal aging and neurodegenerative disorders such as Alzheimer's Disease (AD). Although major efforts to prevent or slow down cognitive decline are largely focused within the central nervous system (CNS), it has become clear that signals from the systemic milieu are closely associated with the dysfunctional brain. In particular, the bidirectional crosstalk between the CNS and peripheral immune system plays a decisive role in shaping neuronal survival and function via neuroimmune, neuroendocrinal and bioenergetic mechanisms. Importantly, it is emerging that some neuroprotective and cognition-strengthening drugs may work by targeting the brain-periphery interactions, which could be intriguingly achieved without entering the CNS. We describe here how recent advances in dissecting cognitive deficits from a systems-perspective have contributed to a non-neurocentric understanding of its pathogenesis and treatment strategy. We also discuss the therapeutic and diagnostic implications of these exciting progresses and consider some key issues in the clinical translation. This article is part of a Special Issue entitled 'Neuroimmunology and Synaptic Function'.

Systemic inflammation impairs attention and cognitive flexibility but not associative learning in aged rats: possible implications for delirium

Delirium is a common and morbid condition in elderly hospitalized patients. Its pathophysiology is poorly understood but inflammation has been implicated based on a clinical association with systemic infection and surgery and preclinical data showing that systemic inflammation adversely affects hippocampus-dependent memory. However, clinical manifestations and imaging studies point to abnormalities not in the hippocampus but in cortical circuits. We therefore tested the hypothesis that systemic inflammation impairs prefrontal cortex function by assessing attention and executive function in aged animals. Aged (24-month-old) Fischer-344 rats received a single intraperitoneal injection of lipopolysaccharide (LPS; 50 μg/kg) or saline and were tested on the attentional set-shifting task (AST), an index of integrity of the prefrontal cortex, on days 1-3 post-injection. Plasma and frontal cortex concentrations of the cytokine TNFα and the chemokine CCL2 were measured by ELISA in separate groups of identically treated, age-matched rats. LPS selectively impaired reversal learning and attentional shifts without affecting discrimination learning in the AST, indicating a deficit in attention and cognitive flexibility but not learning globally. LPS increased plasma TNFα and CCL2 acutely but this resolved within 24-48 h. TNFα in the frontal cortex did not change whereas CCL2 increased nearly threefold 2 h after LPS but normalized by the time behavioral testing started 24 h later. Together, our data indicate that systemic inflammation selectively impairs attention and executive function in aged rodents and that the cognitive deficit is independent of concurrent changes in frontal cortical TNFα and CCL2. Because inattention is a prominent feature of clinical delirium, our data support a role for inflammation in the pathogenesis of this clinical syndrome and suggest this animal model could be useful for studying that relationship further.

Inflammation biomarkers and delirium in critically ill patients

Introduction

Delirium is a common occurrence in critically ill patients and is associated with an increase in morbidity and mortality. Septic patients with delirium may differ from a general critically ill population. The aim of this investigation was to study the relationship between systemic inflammation and the development of delirium in septic and non-septic critically ill patients.

Methods

We performed a prospective cohort study in a 20-bed mixed intensive care unit (ICU) including 78 (delirium = 31; non-delirium = 47) consecutive patients admitted for more than 24 hours. At enrollment, patients were allocated to septic or non-septic groups according to internationally agreed criteria. Delirium was diagnosed using the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) during the first 72 hours of ICU admission. Blood samples were collected within 12 hours of enrollment for determination of tumor necrosis factor (TNF)-α, soluble TNF Receptor (STNFR)-1 and -2, interleukin (IL)-1β, IL-6, IL-10 and adiponectin.

Results

Out of all analyzed biomarkers, only STNFR1 (P = 0.003), STNFR2 (P = 0.005), adiponectin (P = 0.005) and IL-1β (P < 0.001) levels were higher in delirium patients. Adjusting for sepsis and sedation, these biomarkers were also independently associated with delirium occurrence. However, none of them were significant influenced by sepsis.

Conclusions

STNFR1, STNFR2, adiponectin and IL-1β were associated with delirium. Sepsis did not modify the relationship between the biomarkers and delirium occurrence.

Delirium: definition, epidemiology, and diagnosis

This article serves to (1) review the relationship of the terms "delirium" and "encephalopathy," (2) describe delirium as defined in current diagnostic systems, (3) summarize the epidemiology and theories of pathogenesis, (4) review clinical diagnostic approaches, and (5) highlight the history using EEG in the study of delirium in the psychiatric literature. Delirium is an important medical syndrome with significant implications; there is continued need for better physiologic measures of the underlying brain dysfunction.

The association between C-reactive protein and delirium in 710 acute elderly hospital admissions

BACKGROUND

Delirium is a common neuropsychiatric syndrome associated with poor outcomes. Evidence supports a neuroinflammatory etiology, but the role of the inflammatory marker C-reactive protein (C-RP) remains unclear. We investigated the relationship between C-RP and delirium and its severity as well as interaction with medical diagnosis.

METHODS

From an existing database (710 patients over 70 years old admitted to a Medical Acute Admissions Unit) we analyzed data which included C-RP levels, delirium (using the Confusion Assessment Method), and other clinical and demographic factors. Primary diagnoses were grouped (cardiovascular, musculoskeletal, infection, metabolic, and other).

RESULTS

There was a strong association between elevated C-RP and delirium (t = 5.09; p < 0.001), independent of other potential risk factors for delirium (odds ratio (OR) = 1.32 (95% CI: 1.10-1.58) p = 0.003). There was no significant association between C-RP and delirium severity, and between C-RP and delirium in the populations with cardiovascular disease, infection upon admission, or from the metabolic group despite an OR of 2.24 (95% CI: 0.92-5.45). There was an association in the musculoskeletal group (OR 2.19 (95% CI: 1.19-4.02)).

CONCLUSIONS

There is an association between elevated C-RP and delirium. This is strongest in patients admitted with musculoskeletal disease but not in others, implying that C-RP is involved in the genesis of delirium in musculoskeletal disease, but that other factors or processes may be more important in those with cardiovascular disease or infection.

Preoperative cerebrospinal fluid β-Amyloid/Tau ratio and postoperative delirium

Objective

The neuropathogenesis of postoperative delirium remains unknown. Low cerebrospinal fluid (CSF) β-amyloid protein (Aβ) and high CSF Tau levels are associated with Alzheimer's disease. We, therefore, assessed whether lower preoperative CSF Aβ/Tau ratio was associated with higher incidence and greater severity of postoperative delirium.

Methods

One hundred and fifty-three participants (71 ± 5 years, 53% men) who had total hip/knee replacement under spinal anesthesia were enrolled. CSF was obtained during initiation of spinal anesthesia. The incidence and severity of postoperative delirium were determined by Confusion Assessment Method (CAM) and Memorial Delirium Assessment Scale (MDAS) on postoperative day 1 and 2. Aβ40, Aβ42, and Tau levels in the CSF were measured by enzyme-linked immunosorbent assay. The relationships among these variables were determined, adjusting for age and gender.

Results

Participants in the lowest quartile of preoperative CSF Aβ40/Tau and Aβ42/Tau ratio had higher incidence (32% vs. 17%, P = 0.0482) and greater symptom severity of postoperative delirium (Aβ40/Tau ratio: 4 vs. 3, P = 0.034; Aβ42/Tau ratio: 4 vs. 3, P = 0.062, the median of the highest MDAS score) as compared to the combination of the rest of the quartiles. The preoperative CSF Aβ40/Tau or Aβ42/Tau ratio was inversely associated with MDAS score (Aβ40/Tau ratio: −0.12 ± 0.05, P = 0.014, adj. −0.12 ± 0.05, P = 0.018; Aβ42/Tau ratio: −0.65 ± 0.26, P = 0.013, adj. −0.62 ± 0.27, P = 0.022).

Interpretation

Lower CSF Aβ/Tau ratio could be associated with postoperative delirium, pending confirmation of our preliminary results in further studies. These findings suggest potential roles of Aβ and/or Tau in postoperative delirium neuropathogenesis.