Systemic infection and delirium: when cytokines and acetylcholine collide

LncRNA SNHG3 Promotes Sevoflurane-Induced Neuronal Injury by Activating NLRP3 via NEK7

BACKGROUND

Early exposure to sevoflurane may cause brain tissue degeneration; however, the mechanism involved in this process has not been explored. In this study, we investigated the role of long non-coding RNA small nucleolar RNA host gene 3 (lncRNA SNHG3) in sevoflurane-induced neuronal injury.

METHODS

The injury models of HT22 and primary cultures of neurons were constructed using sevoflurane treatment. The WST-8 reduction was detected by CCK-8 assay, the level of inflammatory factors was detected by enzyme-linked immunosorbent assay (ELISA), and cell pyroptosis was detected by flow cytometry. The expression of genes and proteins was detected by qRT-PCR and Western blot, respectively. The level of β-tubulin III in primary cultures of hippocampal neurons was analyzed by immunofluorescence. The relationship among SNHG3, PTBP1 and NEK7 was confirmed by RIP assay.

RESULTS

The expression of SNHG3 and NEK7 were enhanced in sevoflurane-treated HT22 cells. Sevoflurane inhibited the WST-8 reduction in a concentration-dependent manner, promoted the pyroptosis, and increased pyroptosis-related protein expression. SNHG3 knockdown significantly inhibited sevoflurane-induced pyroptosis and inflammatory injury in HT22 cells and primary cultures of neurons. Furthermore, SNHG3 regulated NEK7 expression by binding to PTBP1. NEK7 knockdown reversed the decrease in WST-8 reduction, inhibited pyroptosis, and decreased the release of inflammatory factors and pyroptosis-related protein expression by inactivation of NLRP3 signaling in sevoflurane-induced HT22 cells. Moreover, NEK7 overexpression attenuated the effect of SNHG3 knockdown on neuronal pyroptosis and inflammation injury.

CONCLUSION

Downregulation of SNHG3 attenuates sevoflurane-induced neuronal inflammation and pyroptosis by mediating the NEK7/NLRP3 axis, suggesting that SNHG3 could be a potential target gene for neuronal injury.

Young Nonalcoholic Wernicke Encephalopathy Patient Achieves Remission Following Prolonged Thiamine Treatment and Cognitive Rehabilitation

Wernicke encephalopathy (WE), a neurological emergency commonly associated with alcohol use disorder, results from a severe deficiency of vitamin B1. If left untreated, patients either succumb to the illness or develop chronic Korsakoff's syndrome (KS). Recently, an increasing number of nonalcoholic WE case studies have been published, highlighting a lack of understanding of malnutrition-related disorders among high-functioning patients. We present the case of a 26 year old female who developed life-threatening WE after COVID-19-complicated obesity surgery. She experienced the full triad of WE symptoms, including eye-movement disorders, delirium, and ataxia, and suffered for over 70 days before receiving her initial WE diagnosis. Late treatment resulted in progression of WE symptoms. Despite the severity, the patient achieved remission of some of the symptoms in the post-acute phase due to prolonged parenteral thiamine injections and intensive specialized rehabilitation designed for young traumatic brain injury (TBI) patients. The rehabilitation resulted in gradual remission of amnesia symptomatology, mainly increasing her autonomy. The late recognition of this case highlights the importance of early diagnosis and prompt, targeted intervention in the management of nonalcoholic WE, as well as underscores the potential for positive outcomes after delayed treatment through intensive cognitive rehabilitation in specialized treatment centers.

High Mobility Group Box 1 (HMGB1): Potential Target in Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy (SAE) remains a challenge for intensivists that is exacerbated by lack of an effective diagnostic tool and an unambiguous definition to properly identify SAE patients. Risk factors for SAE development include age, genetic factors as well as pre-existing neuropsychiatric conditions. Sepsis due to certain infection sites/origins might be more prone to encephalopathy development than other cases. Currently, ICU management of SAE is mainly based on non-pharmacological support. Pre-clinical studies have described the role of the alarmin high mobility group box 1 (HMGB1) in the complex pathogenesis of SAE. Although there are limited data available about the role of HMGB1 in neuroinflammation following sepsis, it has been implicated in other neurologic disorders, where its translocation from the nucleus to the extracellular space has been found to trigger neuroinflammatory reactions and disrupt the blood–brain barrier. Negating the inflammatory cascade, by targeting HMGB1, may be a strategy to complement non-pharmacologic interventions directed against encephalopathy. This review describes inflammatory cascades implicating HMGB1 and strategies for its use to mitigate sepsis-induced encephalopathy.

In a secondary analysis from a randomised, double-blind placebo-controlled trial Dexmedetomidine blocks cholinergic dysregulation in delirium pathogenesis in patients with major surgery

Dexmedetomidine is an alpha-2 adrenoreceptor agonist with anti-inflammatory and anti-delirogenic properties. Pathogenesis of postoperative delirium (POD) includes cholinergic dysfunction and deregulated inflammatory response to surgical trauma. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are discussed as biomarkers for both POD and severity in acute inflammation. To show whether there is a link between blood cholinesterase activities and dexmedetomidine, we performed a secondary analysis of a randomised, double-blind, placebo-controlled trial that recently showed a lower incidence of POD in the dexmedetomidine group. Abdominal or cardiac surgical patients aged ≥ 60 years were randomised to receive dexmedetomidine or placebo intra- and postoperatively in addition to standard general anaesthesia. We analysed the course of perioperative cholinesterase activities of 56 patients, measured preoperatively and twice postoperatively. Dexmedetomidine resulted in no change in AChE activity and caused a rapid recovery of BChE activity after an initial decrease, while placebo showed a significant decrease in both cholinesterase activities. There were no significant between-group differences at any point in time. From these data it can be assumed that dexmedetomidine could alleviate POD via altering the cholinergic anti-inflammatory pathway (CAIP). We advocate for further investigations to show the direct connection between dexmedetomidine and cholinesterase activity.

Effects of Melatonin Administration on Post-Stroke Delirium in Patients with Intracerebral Hemorrhage

Post-stroke delirium (PSD) after intracerebral hemorrhage (ICH) is considered to be even more detrimental compared to that after ischemic stroke. Treatment options for post-ICH PSD remain limited. This study aimed at investigating to what extent prophylactic melatonin administration may have beneficial effects on post-ICH PSD. We performed a mono-centric, non-randomized, non-blinded, prospective cohort study, including 339 consecutive ICH patients admitted to the Stroke Unit (SU) from December 2015 to December 2020. The cohort consisted of ICH patients who underwent standard care (defined as the control group) and ICH patients who additionally received prophylactic melatonin (2 mg per day, at night) within 24 h of ICH onset until the discharge from the SU. The primary endpoint was post-ICH PSD prevalence. The secondary endpoints were: (i) PSD duration and (ii) the duration of SU stay. The PSD prevalence was higher in the melatonin treated cohort compared to the propensity score-matched (PSM) control group. Post-ICH PSD patients receiving melatonin had shorter SU-stay durations, and shorter PSD durations, although not statistically significant. This study shows no efficacy in limiting post-ICH PSD with preventive melatonin administration.

Proteomics for the Discovery of Clinical Delirium Biomarkers: A Systematic Review of Major Studies

Delirium represents a significant health care burden, diagnosed in more than 2 million elderly Americans each year. In the surgical population, delirium remains the most common complication among elderly patients, and is associated with longer hospital stays, higher costs of care, increased mortality, and functional impairment. The pathomechanism of disease is poorly understood, with current diagnostic approaches somewhat subjective and arbitrary, and definitive diagnostic biomarkers are currently lacking. Despite the recent interest in delirium research, biomarker discovery for it remains new. Most attempts to discover biomarkers are targeted studies that seek to assess the involvement of one or more members of a focused panel of candidates in delirium. For a more unbiased, system-biology view, we searched literature from Medical Literature Analysis and Retrieval System Online (MEDLINE), Cochrane Central, Web of Science, SCOPUS, and Dimensions between 2016 and 2021 for untargeted proteomic discovery studies for biomarkers of delirium conducted on human geriatric subjects. Two reviewers conducted an independent review of all search results and resolved discordance by consensus. From an overall search of 1172 publications, 8 peer-reviewed studies met our defined inclusion criteria. The 370 unique perioperative biomarkers identified in these reports are enriched in pathways involving activation of the immune system, inflammatory response, and the coagulation cascade. The most frequently identified biomarker was interleukin-6 (IL-6). By reviewing the distribution of protein biomarker candidates from these studies, we conclude that a panel of proteins, rather than a single biomarker, would allow for discriminating delirium cases from noncases. The paucity of hypothesis-generating studies in the peer-reviewed literature also suggests that a system-biology view of delirium pathomechanisms has yet to fully emerge.

Elevated sTREM2 and NFL levels in patients with sepsis associated encephalopathy

PURPOSE

Sepsis-associated encephalopathy (SAE) is a common manifestation of sepsis that may lead to cognitive decline. Our aim was to investigate whether the neurofilament light chain (NFL) and soluble triggering receptor expressed on myeloid cells 2 (sTREM2) could be utilized as prognostic biomarkers in SAE.

MATERIALS AND METHODS

In this prospective observational study, baseline serum levels of sTREM2 and cerebrospinal fluid (CSF) levels of sTREM2 and NFL were measured by ELISA in 11 SAE patients and controls. Patients underwent daily neurological examination. Brain magnetic resonance imaging (MRI) and standard electroencephalography (EEG) were performed. Cognitive dysfunction was longitudinally assessed after discharge in 4 SAE patients using the Mini-Mental State Examination (MMSE) and Addenbrooke's Cognitive Examination-Revised (ACE-R) tests.

RESULTS

SAE patients showed higher CSF sTREM2 and NFL levels than controls. sTREM2 and NFL levels were not correlated with the severity measures of sepsis. Three months after discharge, 2 SAE patients displayed ACE-R scores congruent with mild cognitive impairment (MCI), persisting in one patient 12 months after discharge. SAE patients with MCI showed higher CSF NFL levels, bacteremia, and abnormal brain MRI. Patients with increased serum/CSF sTREM2 levels showed trends towards displaying poorer attention/orientation and visuo-spatial skills.

CONCLUSIONS

sTREM2 and NFL levels may serve as a prognostic biomarker for cognitive decline in SAE. These results lend further support for the involvement of glial activation and neuroaxonal degeneration in the physiopathology of SAE.

Endothelial glycocalyx-associated molecules as potential serological markers for sepsis-associated encephalopathy: A systematic review and meta-analysis

BACKGROUND

Sepsis-associated encephalopathy (SAE) is characterized by a diffuse cerebral dysfunction that accompanies sepsis in the absence of direct central nervous system infection. The endothelial glycocalyx is a dynamic mesh containing heparan sulfate linked to proteoglycans and glycoproteins, including selectins and vascular/intercellular adhesion molecules (V/I-CAMs), which protects the endothelium while mediating mechano-signal transduction between the blood and vascular wall. During severe inflammatory states, components of the glycocalyx are shed into the circulation and can be detected in soluble forms. Currently, SAE remains a diagnosis of exclusion and limited information is available on the utility of glycocalyx-associated molecules as biomarkers for SAE. We set out to synthesize all available evidence on the association between circulating molecules released from the endothelial glycocalyx surface during sepsis and sepsis-associated encephalopathy.

METHODS

MEDLINE (PubMed) and EMBASE were searched since inception until May 2, 2022 to identify eligible studies. Any comparative observational study: i) evaluating the association between sepsis and cognitive decline and ii) providing information on level of circulating glycocalyx-associated molecules was eligible for inclusion.

RESULTS

Four case-control studies with 160 patients met the inclusion criteria. Meta-analysis of biomarkers ICAM-1 (SMD 0.41; 95% CI 0.05-0.76; p = 0.03; I2 = 50%) and VCAM-1 (SMD 0.55; 95% CI 0.12-0.98; p = 0.01; I2 = 82%) revealed higher pooled mean concentration in patients with SAE compared to the patients with sepsis alone. Single studies reported elevated levels of P-selectin (MD 0.80; 95% CI -17.77-19.37), E-selectin (MD 96.40; 95% Cl 37.90-154.90), heparan sulfate NS2S (MD 19.41; 95% CI 13.37-25.46), and heparan sulfate NS+NS2S+NS6S (MD 67.00; 95% CI 31.00-103.00) in patients with SAE compared to the patients with sepsis alone.

CONCLUSION

Plasma glycocalyx-associated molecules are elevated in SAE and may be useful for early identification of cognitive decline in sepsis patients.

Activation of glucagon-like peptide-1 receptor in microglia exerts protective effects against sepsis-induced encephalopathy via attenuating endoplasmic reticulum stress-associated inflammation and apoptosis in a mouse model of sepsis

Sepsis-induced encephalopathy (SAE) is a detrimental complication in patients with severe sepsis, while there is still no effective treatment. Previous studies have elucidated the neuroprotective effects of glucagon-like peptide-1 receptor (GLP-1R) agonists. However, the role of GLP-1R agonists in the pathological process of SAE is unclear. Here, we found that GLP-1R was up-regulated in the microglia of septic mice. The activation of GLP-1R with Liraglutide could inhibit endoplasmic reticulum stress (ER stress) and associated inflammatory response as well as apoptosis triggered by LPS or tunicamycin (TM) in BV2 cells. In vivo experiments confirmed the benefits of Liraglutide in the regulation of microglial activation, ER stress, inflammation, and apoptosis in the hippocampus of septic mice. Additionally, the survival rate and cognitive dysfunction of septic mice were also improved after Liraglutide administration. Mechanically, cAMP/PKA/CREB signaling is involved in the protection of ER stress-induced inflammation and apoptosis in cultured microglial cells under LPS or TM stimulations. In conclusion, we speculated that GLP-1/GLP-1R activation in microglia might be a potential therapeutic target for the treatment of SAE.

Using Machine Learning Algorithms to Predict High-Risk Factors for Postoperative Delirium in Elderly Patients

Purpose

Postoperative delirium (POD) is a common postoperative complication in elderly patients, and it greatly affects the short-term and long-term prognosis of patients. The purpose of this study was to develop a machine learning model to identify preoperative, intraoperative and postoperative high-risk factors and predict the occurrence of delirium after nonbrain surgery in elderly patients.

Patients and Methods

A total of 950 elderly patients were included in the study, including 132 patients with POD. We collected 30 characteristic variables, including patient demographic characteristics, basic medical history, preoperative examination characteristics, type of surgery, and intraoperative information. Three machine learning algorithms, multilayer perceptron (MLP), extreme gradient boosting (XGBoost), and k-nearest neighbor algorithm (KNN), were applied to construct the model, and the k-fold cross-validation method, ROC curve, calibration curve, decision curve analysis (DCA) and external validation were used for model evaluation.

Results

XGBoost showed the best performance among the three prediction models. The ROC curve results showed that XGBoost had a high area under the curve (AUC) value of 0.982 in the training set; the AUC value in the validation set was 0.924, and the prediction model was highly accurate. The k-fold cross-validation method was used for internal validation, and the XGBoost model was stable The calibration curve showed high predictive power of the XGBoost model. The DCA curve showed a higher benefit rate for patients who received interventional treatment under the XGBoost model. The AUC value for the external validation set was 0.88, indicating that the predictive model was extrapolative.

Conclusion

The prediction model of POD derived from the machine learning algorithm in this study has high prediction accuracy and clinical utility, which is beneficial for clinicians to diagnose and treat patients in a timely manner.

Delirium-related psychiatric and neurocognitive impairment and the association with post-intensive care syndrome-A narrative review

INTRODUCTION

Delirium is common among patients admitted to the intensive care unit (ICU) and its impact on the neurocognitive and psychiatric state of survivors is of great interest. These new-onset or worsening conditions, together with physical alterations, are called post-intensive care syndrome (PICS). Our aim is to update on the latest screening and follow-up options for psychological and cognitive sequelae of PICS.

METHOD

This narrative review discusses the occurrence of delirium in ICU settings and the relatively new concept of PICS. Psychiatric and neurocognitive morbidities that may occur in survivors of critical illness following delirium are addressed. Future perspectives for practice and research are discussed.

RESULTS

There is no "gold standard" for diagnosing delirium in the ICU, but two extensively validated tools, the confusion assessment method for the ICU and the intensive care delirium screening checklist, are often used. PICS complaints are frequent in ICU survivors who have suffered delirium and have been recognized as an important public health and socio-economic problem worldwide. Depression, anxiety, post-traumatic stress disorder, and long-term cognitive impairment are recurrently exhibited. Screening tools for these deficits are discussed, as well as the suggestion of early assessment after discharge and at 3 and 12 months.

CONCLUSIONS

Delirium is a complex but common phenomenon in the ICU and a risk factor for PICS. Its diagnosis is challenging with potential long-term adverse outcomes, including psychiatric and cognitive difficulties. The implementation of screening and follow-up protocols for PICS sequelae is warranted to ensure early detection and appropriate management.

Processed electroencephalography-guided general anaesthesia to reduce postoperative delirium: a systematic review and meta-analysis

BACKGROUND

Postoperative delirium (POD) is the most common serious postoperative complication in older adults. It has uncertain aetiology, limited preventative strategies, and poor long-term outcomes. This updated systematic review and meta-analysis aimed to estimate the effect of processed electroencephalography (pEEG)-guided general anaesthesia during surgery on POD incidence.

METHODS

We performed a systematic review and meta-analysis by searching OVID MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) electronic databases. Studies of adult patients having general anaesthesia for any surgery where pEEG was used and POD was an outcome measure were included. Full-text reports of RCTs published from database inception until August 28, 2021, were included. Trials were excluded if sedation rather than general anaesthesia was administered, or the setting was intensive care. The primary outcome was POD assessed by validated tools. The study was prospectively registered with PROSPERO.

RESULTS

Nine studies, which included 4648 eligible subjects, were identified. The incidence of POD in the pEEG-guided general anaesthesia or lighter pEEG target group was 19.0% (440/2310) compared with 23.3% (545/2338) in the usual care or deeper pEEG target group (pooled odds ratio=0.78; 95% confidence interval, 0.60-1.00; P=0.054). Significant heterogeneity was detected (I²=53%).

CONCLUSIONS

Our primary analysis demonstrated a highly sensitive result with a pooled analysis of trials in which the intervention group adhered to manufacturer's recommended guidelines, showing reduced incidence of POD with pEEG guidance. High clinical heterogeneity limits inferences from this and any future meta-analyses.

CLINICAL TRIAL REGISTRATION

CRD42020199404 (PROSPERO).

Intermittent systemic exposure to lipopolysaccharide-induced inflammation disrupts hippocampal long-term potentiation and impairs cognition in aging male mice

Age-related cognitive decline, a common component of the brain aging process, is associated with significant impairment in daily functioning and quality of life among geriatric adults. While the complexity of mechanisms underlying cognitive aging are still being elucidated, microbial exposure and the multifactorial inflammatory cascades associated with systemic infections are emerging as potential drivers of neurological senescence. The negative cognitive and neurobiological consequences of a single pathogen-associated inflammatory experience, such as that modeled through treatment with lipopolysaccharide (LPS), are well documented. Yet, the brain aging impacts of repeated, intermittent inflammatory challenges are less well studied. To extend the emerging literature assessing the impact of infection burden on cognitive function among normally aging mice, here, we repeatedly exposed adult mice to intermittent LPS challenges during the aging period. Male 10-month-old C57BL6 mice were systemically administered escalating doses of LPS once every two weeks for 2.5 months. We evaluated cognitive consequences using the non-spatial step-through inhibitory avoidance task, and both spatial working and reference memory versions of the Morris water maze. We also probed several potential mechanisms, including cortical and hippocampal cytokine/chemokine gene expression, as well as hippocampal neuronal function via extracellular field potential recordings. Though there was limited evidence for an ongoing inflammatory state in cortex and hippocampus, we observed impaired learning and memory and a disruption of hippocampal long-term potentiation. These data suggest that a history of intermittent exposure to LPS-induced inflammation is associated with subtle but significantly impaired cognition among normally aging mice. The broader impact of these findings may have important implications for standard of care involving infections in aging individuals or populations at-risk for dementia.

P2X7 receptor contributes to long-term neuroinflammation and cognitive impairment in sepsis-surviving mice

Introduction: Sepsis is defined as a multifactorial debilitating condition with high risks of death. The intense inflammatory response causes deleterious effects on the brain, a condition called sepsis-associated encephalopathy. Neuroinflammation or pathogen recognition are able to stress cells, resulting in ATP (Adenosine Triphosphate) release and P2X7 receptor activation, which is abundantly expressed in the brain. The P2X7 receptor contributes to chronic neurodegenerative and neuroinflammatory diseases; however, its function in long-term neurological impairment caused by sepsis remains unclear. Therefore, we sought to evaluate the effects of P2X7 receptor activation in neuroinflammatory and behavioral changes in sepsis-surviving mice. Methods: Sepsis was induced in wild-type (WT), P2X7^-/-, and BBG (Brilliant Blue G)-treated mice by cecal ligation and perforation (CLP). On the thirteenth day after the surgery, the cognitive function of mice was assessed using the novel recognition object and Water T-maze tests. Acetylcholinesterase (AChE) activity, microglial and astrocytic activation markers, and cytokine production were also evaluated. Results: Initially, we observed that both WT and P2X7^-/- sepsis-surviving mice showed memory impairment 13 days after surgery, once they did not differentiate between novel and familiar objects. Both groups of animals presented increased AChE activity in the hippocampus and cerebral cortex. However, the absence of P2X7 prevented partly this increase in the cerebral cortex. Likewise, P2X7 absence decreased ionized calcium-binding protein 1 (Iba^-1) and glial fibrillary acidic protein (GFAP) upregulation in the cerebral cortex of sepsis-surviving animals. There was an increase in GFAP protein levels in the cerebral cortex but not in the hippocampus of both WT and P2X7^-/- sepsis-surviving animals. Pharmacological inhibition or genetic deletion of P2X7 receptor attenuated the production of Interleukin-1β (IL-1β), Tumor necrosis factor-α (TNF-α), and Interleukin-10 (IL-10). Conclusion: The modulation of the P2X7 receptor in sepsis-surviving animals may reduce neuroinflammation and prevent cognitive impairment due to sepsis-associated encephalopathy, being considered an important therapeutic target.

Genistein attenuates neuroinflammation and oxidative stress and improves cognitive impairment in a rat model of sepsis-associated encephalopathy: potential role of the Nrf2 signaling pathway

Oxidative stress and inflammation seem to be the main factors responsible for cognitive impairment in sepsis. Genistein (GEN) is claimed to exert many beneficial effects on health, however, its possible effects on brain sepsis remains unclear. Here, we assess the influence and underling mechanisms of GEN on cognitive impairments in cecal ligation and puncture (CLP)-induced septic model. Rats were randomly divided into Sham, Sham + GEN, CLP, CLP + GEN gropus. Rats were treated with GEN (15 mg/kg at 0 and 12 h after CLP, i.p). Twenty-four hours after CLP, protein levels of cytokines, NF-kB and Nrf2, myeloperoxidase (MPO) activity, oxidative damage to lipids and proteins, the activities of antioxidant enzymes and the expression of Nrf2-target genes were evaluated in the hippocampus. At 10 days after sepsis induction, behavioral tests were conducted to evaluate cognitive impairment. The results indicate that GEN can enhance survival percentage and improve cognitive function. Genistein administration significantly reduced TNF-α and IL-1β levels, MPO activity and protein level of NF-kB in the hippocampus of septic rats. Genistein also decreased the levels of oxidative stress parameters (MDA and protein carbonyls) and elevated the activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in septic rats. Furthermore, nuclear Nrf2 and the expression of HO-1 and NQO-1 were also elevated by GEN treatment. These findings suggest that GEN improves cognition impairment in septic rats via decreasing inflammatory responses and oxidative stress, and activation of the Nrf2 pathway.

The Key Drivers of Brain Injury by Systemic Inflammatory Responses after Sepsis: Microglia and Neuroinflammation

Sepsis is a leading cause of intensive care unit admission and death worldwide. Most surviving patients show acute or chronic mental disorders, which are known as sepsis-associated encephalopathy (SAE). Although accumulating studies in the past two decades focused on the pathogenesis of SAE, a systematic review of retrospective studies which exclusively focuses on the inflammatory mechanisms of SAE has been lacking yet. This review summarizes the recent advance in the field of neuroinflammation and sheds light on the activation of microglia in SAE. Activation of microglia predominates neuroinflammation. As the gene expression profile changes, microglia show heterogeneous characterizations throughout all stages of SAE. Here, we summarize the systemic inflammation following sepsis and also the relationship of microglial diversity and neuroinflammation. Moreover, a collection of neuroinflammation-related dysfunction has also been reviewed to illustrate the possible mechanisms for SAE. In addition, promising pharmacological or non-pharmacological therapeutic strategies, especially those which target neuroinflammation or microglia, are also concluded in the final part of this review. Collectively, clarification of the vital relationship between neuroinflammation and SAE-related mental disorders would significantly improve our understanding of the pathophysiological mechanisms in SAE and therefore provide potential targets for therapies of SAE aimed at inhibiting neuroinflammation.

Association between cholinesterase activity and critical illness brain dysfunction

BACKGROUND

Delirium is a frequent manifestation of acute brain dysfunction and is associated with cognitive impairment. The hypothesized mechanism of brain dysfunction during critical illness is centered on neuroinflammation, regulated in part by the cholinergic system. Point-of-care serum cholinesterase enzyme activity measurements serve as a real-time index of cholinergic activity. We hypothesized that cholinesterase activity during critical illness would be associated with delirium in the intensive care unit (ICU) and cognitive impairment after discharge.

METHODS

We enrolled adults with respiratory failure and/or shock and measured plasma acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity on days 1, 3, 5, and 7 after enrollment. AChE values were also normalized per gram of hemoglobin (AChE/Hgb). We assessed for coma and delirium twice daily using the Richmond Agitation Sedation Scale and the Confusion Assessment Method for the ICU to evaluate daily mental status (delirium, coma, normal) and days alive without delirium or coma. Cognitive impairment, disability, and health-related quality of life were assessed at up to 6 months post-discharge. We used multivariable regression to determine whether AChE, AChE/Hgb, and BChE activity were associated with outcomes after adjusting for relevant covariates.

RESULTS

We included 272 critically ill patients who were a median (IQR) age 56 (39-67) years and had a median Sequential Organ Failure Assessment score at enrollment of 8 (5-11). Higher daily AChE levels were associated with increased odds of being delirious versus normal mental status on the same day (Odds Ratio [95% Confidence Interval] 1.64 [1.11, 2.43]; P = 0.045). AChE/Hgb and BChE activity levels were not associated with delirious mental status. Lower enrollment BChE was associated with fewer days alive without delirium or coma (P = 0.048). AChE, AChE/Hgb, and BChE levels were not significantly associated with cognitive impairment, disability, or quality of life after discharge.

CONCLUSION

Cholinesterase activity during critical illness is associated with delirium but not with outcomes after discharge, findings that may reflect mechanisms of acute brain organ dysfunction.

TRIAL REGISTRATION

NCT03098472. Registered 31 March 2017.

Reactive Microgliosis in Sepsis-Associated and Acute Hepatic Encephalopathies: An Ultrastructural Study

Sepsis and acute liver failure are associated with severe endogenous intoxication. Microglia, which are the resident immune brain cells, play diverse roles in central nervous system development, surveillance, and defense, as well as contributing to neuroinflammatory reactions. In particular, microglia are fundamental to the pathophysiology of reactive toxic encephalopathies. We analyzed microglial ultrastructure, morphotypes, and phagocytosis in the sensorimotor cortex of cecal ligation and puncture (CLP) and acetaminophen-induced liver failure (AILF) Wistar rats. A CLP model induced a gradual shift of ~50% of surveillant microglia to amoeboid hypertrophic-like and gitter cell-like reactive phenotypes with active phagocytosis and frequent contacts with damaged neurons. In contrast, AILF microglia exhibited amoeboid, rod-like, and hypertrophic-like reactive morphotypes with minimal indications for efficient phagocytosis, and were mostly in contact with edematous astrocytes. Close interactions of reactive microglia with neurons, astrocytes, and blood-brain barrier components reflect an active contribution of these cells to the tissue adaptation and cellular remodeling to toxic brain damage. Partial disability of reactive microglia may affect the integrity and metabolism in all tissue compartments, leading to failure of the compensatory mechanisms in acute endogenous toxic encephalopathies.

A Clinician's View of Wernicke-Korsakoff Syndrome

The purpose of this article is to improve recognition and treatment of Wernicke-Korsakoff syndrome. It is well known that Korsakoff syndrome is a chronic amnesia resulting from unrecognized or undertreated Wernicke encephalopathy and is caused by thiamine (vitamin B1) deficiency. The clinical presentation of thiamine deficiency includes loss of appetite, dizziness, tachycardia, and urinary bladder retention. These symptoms can be attributed to anticholinergic autonomic dysfunction, as well as confusion or delirium, which is part of the classic triad of Wernicke encephalopathy. Severe concomitant infections including sepsis of unknown origin are common during the Wernicke phase. These infections can be prodromal signs of severe thiamine deficiency, as has been shown in select case descriptions which present infections and lactic acidosis. The clinical symptoms of Wernicke delirium commonly arise within a few days before or during hospitalization and may occur as part of a refeeding syndrome. Wernicke encephalopathy is mostly related to alcohol addiction, but can also occur in other conditions, such as bariatric surgery, hyperemesis gravidarum, and anorexia nervosa. Alcohol related Wernicke encephalopathy may be identified by the presence of a delirium in malnourished alcoholic patients who have trouble walking. The onset of non-alcohol-related Wernicke encephalopathy is often characterized by vomiting, weight loss, and symptoms such as visual complaints due to optic neuropathy in thiamine deficiency. Regarding thiamine therapy, patients with hypomagnesemia may fail to respond to thiamine. This may especially be the case in the context of alcohol withdrawal or in adverse side effects of proton pump inhibitors combined with diuretics. Clinician awareness of the clinical significance of Wernicke delirium, urinary bladder retention, comorbid infections, refeeding syndrome, and hypomagnesemia may contribute to the recognition and treatment of the Wernicke-Korsakoff syndrome.

Association of Atrial Fibrillation and Cardioembolic Stroke with Poststroke Delirium Susceptibility: A Systematic Review and Meta-Analysis of Observational Studies

BACKGROUND

Several studies have shown atrial fibrillation (AF) and cardioembolic stroke (CES) to be associated with the risk of poststroke delirium (PSD). However, other studies have reported inconsistent results. We performed a comprehensive meta-analysis to clarify the associations between AF and CES and PSD susceptibility.

METHODS

We searched relevant studies meeting inclusion criteria in PubMed, Google Scholar, and Web of Science. Useful data were pooled, and odds ratios and 95% confidence intervals were calculated. We also assessed heterogeneity among studies, performed sensitivity analyses, and estimated publication bias.

RESULTS

This meta-analysis containing 18 observational studies proved that AF (odds ratio =2.30, 95% confidence interval = 2.00-2.65, P < 0.0001) was associated with an increased risk of PSD. CES was also found to have a higher risk of delirium compared with other types of stroke based on the Trial of Org 10172 in Acute Stroke Treatment classification (odds ratio = 2.02, 95% confidence interval = 1.47-2.79, P < 0.0001).

CONCLUSIONS

Our meta-analysis suggested that AF and CES contribute to increased risk of PSD.

Long-term cognitive performance and its relation to anti-inflammatory therapy in a cohort of survivors of severe COVID-19

Background and objectives

Long-term cognitive performance data in former critically ill COVID-19 patients are sparse. Current evidence suggests that cognitive decline is related to neuroinflammation, which might be attenuated by COVID-19 related anti-inflammatory therapies. The objective of this prospective cohort study was to study long term cognitive outcomes following severe COVID-19 and the relation to anti-inflammatory therapies.

Methods

Prospective observational cohort of patients that survived an intensive care unit (ICU) admission due to severe COVID-19. Six months after hospital discharge, we extensively assessed both objective cognitive functioning and subjective cognitive complaints. Furthermore, patients were stratified in cohorts according to their anti-inflammatory treatment (i.e. no immunomodulatory therapy, dexamethasone, or both dexamethasone and interleukin-6 receptor antagonist tocilizumab).

Results

96 patients were included (March 2020–June 2021, median [IQR] age 61 [55–69] years). 91% received invasive mechanical ventilation, and mean ± SD severity-of-disease APACHE–II–score at admission was 15.8 ± 4.1. After 6.5 ± 1.3 months, 27% of patients scored cognitively impaired. Patients that did or did not develop cognitive impairments were similar in ICU-admission parameters, clinical course and delirium incidence. Patients with subjective cognitive complaints (20%) were more likely women (61% vs 26%), and had a shorter ICU stay (median [IQR] 8 [5–15] vs 18 [9–31], p = 0.002). Objective cognitive dysfunction did not correlate with subjective cognitive dysfunction. 27% of the participants received dexamethasone during intensive care admission, 44% received additional tocilizumab and 29% received neither. Overall occurrence and severity of cognitive dysfunction were not affected by anti-inflammatory therapy, although patients treated with both dexamethasone and tocilizumab had worse executive functioning scores (Trail Making Test interference) than patients without anti-inflammatory treatment (T-score 40.3 ± 13.5 vs 49.1 ± 9.3, p = 0.007).

Discussion

A relevant proportion of critically ill COVID-19 patients shows deficits in long-term cognitive functioning. Apart from more pronounced executive dysfunction, overall, anti-inflammatory therapy appeared not to affect long-term cognitive performance. Our findings provide insight in long-term cognitive outcomes in patients who survived COVID-19, that may facilitate health-care providers counseling patients and their caregivers.

•

Up to a third of survivors of severe COVID-19 develops long-term cognitive impairment.

•

Subjective cognitive complaints six months following severe COVID-19 do not correlate with objective cognitive impairment.

•

COVID-19 related immunomodulatory therapy is not associated with the overall incidence of cognitive dysfunction.

Microglial Response in Triggering Receptor Expressed on Myeloid Cells 2 (Trem2) Knock-Out Mice After Systemic Stimulation with Escherichia Coli

BACKGROUND

Systemic infection is an important risk factor for delirium, associated with neurodegeneration and subsequent cognitive impairment in older people. Microglial cell response is a known key player in this process and we hypothesize that the triggering receptor expressed on myeloid cells 2 (TREM2) plays an important role in the regulation of this response.

METHODS

8- to 10-week old male wild-type (WT) and TREM2 knock-out (Trem2^-/-) mice were intraperitoneally inoculated with live Escherichia coli (E. coli) or saline. After inoculation, all mice were treated with ceftriaxone (an antimicrobial drug) at 12 and 24 hours and were sacrificed after 2 and 3 days. Microglial response was determined by immunohistochemical staining with an ionized calcium-binding adaptor molecule 1 (Iba-1) antibody and flow cytometry. mRNA expression of pro- and anti-inflammatory mediators was measured to quantify the inflammatory response.

RESULTS

We observed increased Iba-1 positive cells number in thalamus of Trem2^-/- mice at 3d after inoculation compared to WT mice (mean 120 cell/mm² [SD 8] vs. 105 cell/mm² [SD 11]; p=0.03). Flow cytometry showed no differences in forward scatter or expression of CD11b, CD45 and CD14 between WT and Trem2^-/- mice. The brain mRNA expression levels of tumor necrosis factor alpha (TNF-α) of Trem2^-/- mice at 2d were higher compared to WT mice (p=0.003). Higher mRNA expression of interleukin 1 beta (IL-1β), Iba-1, CD11b and mitogen-activated protein kinase 1 (MAPK-1) was found in brain of WT mice at 2d compared to Trem2^-/- mice (respectively p=0.02; p=0.001; p=0.03 and p=0.02). In spleen there were no differences in inflammatory mediators, between WT and Trem2^-/- mice.

INTERPRETATION

Although the loss of function of TREM2 during systemic infection led to an increased number of activated microglia in the thalamus, we did not observe a consistent increase in expression of inflammatory genes in the brain. The role of TREM2 in the neuro-inflammatory response following systemic infection therefore appears to be limited.

Sevoflurane exposure induces neurotoxicity by regulating mitochondrial function of microglia due to NAD insufficiency

Developmental neurons received with sevoflurane, the commonly used inhalational anesthetic agent in clinical surgery, several times tend to be destroyed. Microglia, the resident immune cells of the central nervous system (CNS), are activated after sevoflurane exposure, accompanied by releasing proinflammatory cytokines that damage developing neurons. The sevoflurane-induced neurotoxicity could be attributed to activated microglia presenting proinflammatory and anti-inflammatory functions. Proinflammatory microglia release cytokines to impair the CNS, while anti-inflammatory microglia engulf damaged neurons to maintain CNS homeostasis. Sevoflurane exposure promotes the secretion of proinflammatory cytokines by microglia, inhibiting the microglial phagocytic function. Microglia with poor phagocytic function cannot engulf damaged neurons, leading to the accumulation of damaged neurons. The mechanism underlying poor phagocytic function may be attributed to mitochondrial dysfunction of microglia induced by sevoflurane exposure, in which affected mitochondria cannot generate adequate ATP and NAD to satisfy the energy demand. We discovered that sevoflurane treatment impaired the mitochondrial metabolism of microglia, which resulted in NAD deficiency and couldn’t produce sufficient energy to clear damaged neurons to maintain CNS development. Our findings provide an explanation of a new mechanism underlying sevoflurane-induced neurotoxicity.

Immunological risk factors for sepsis-associated delirium and mortality in ICU patients

Background

A major challenge in intervention of critical patients, especially sepsis-associated delirium (SAD) intervention, is the lack of predictive risk factors. As sepsis and SAD are heavily entangled with inflammatory and immunological processes, to identify the risk factors of SAD and mortality in the intensive care unit (ICU) and determine the underlying molecular mechanisms, the peripheral immune profiles of patients in the ICU were characterized.

Methods

This study contains a cohort of 52 critical patients who were admitted to the ICU of the First Affiliated Hospital of Jinan University. Comorbidity, including sepsis and SAD, of this cohort was diagnosed and recorded. Furthermore, peripheral blood samples were collected on days 1, 3, and 5 of admission for peripheral immune profiling with blood routine examination, flow cytometry, ELISA, RNA-seq, and qPCR.

Results

The patients with SAD had higher mortality during ICU admission and within 28 days of discharge. Compared with survivors, nonsurvivors had higher neutrophilic granulocyte percentage, higher CRP concentration, lower monocyte count, lower monocyte percentage, lower C3 complement level, higher CD14^loCD16⁺ monocytes percentage, and higher levels of IL-6 and TNFα. The CD14^hiCD16^- monocyte percentage manifested favorable prediction values for the occurrence of SAD. Differentially expressed genes between the nonsurvival and survival groups were mainly associated with immune response and metabolism process. The longitudinal expression pattern of SLC2A1 and STIMATE were different between nonsurvivors and survivors, which were validated by qPCR.

Conclusions

Nonsurvival critical patients have a distinct immune profile when compared with survival patients. CD14^hiCD16^- monocyte prevalence and expression levels of SLC2A1 and STIMATE may be predictors of SAD and 28-day mortality in ICU patients.

Association of cholinesterase activities and POD in older adult abdominal surgical patients

Background

Postoperative delirium (POD) is a frequent complication after surgery. Older adult patients undergoing abdominal surgery are at higher risk for developing POD. Studies on the association of cholinesterase activities and POD are rare, but leading hypotheses implicate that the cholinergic pathway might play an important role in neuroinflammation and development of POD. The objective of this study was to figure out if there is an association between the development of POD and acetyl- and butyrylcholinesterase (AChE and BuChE) activities in older adult patients undergoing abdominal surgery.

Methods

The investigation was performed with a subpopulation of BioCog study patients. The BioCog project (http://www.biocog.eu) is a prospective multicenter observational study in older adult surgical patients. Patients ≥ 65 years undergoing elective surgery of at least 60 minutes who scored more than 23 points in the Mini-Mental-State-Examination were included. POD was assessed twice a day on seven consecutive days after the surgery, using the test instruments Nursing Delirium Screening Scale (Nu-Desc) and Confusion Assessment Method (CAM and CAM-ICU) and a patient chart review. Pre- and postoperative blood cholinesterase activities were measured with a photometric rapid-point-of-care-testing. The association between cholinesterase activities and POD was analyzed in a subpopulation of abdominal surgical patients using multivariable logistic regression analysis adjusting for confounders.

Results

One hundred twenty-seven patients were included for analysis (mean age 73 years, 59% female). Fifty-two patients (41%) fulfilled the criteria of POD. These patients were significantly older, had a longer time of surgery and anesthesia and achieved higher comorbidity scores compared to patients without POD. After adjusting for age, duration of surgery and charlson comorbity index, we found an association between pre- and postoperative AChE activity (U/gHb) and the development of POD (Odds ratio (OR), [95% confidence interval (CI)], preoperative 0.95 [0.89–1.00], postoperative 0.94 [0.89–1.00]).

Conclusions

We found an association between POD and AChE activity and provided new information considering patients with abdominal surgery. Future analyses should examine course dynamics of postoperative cholinesterase activities in order to clarify interactions between the cholinergic system and pathophysiological mechanisms leading to POD.

Trial registration

ClinicalTrials.gov: NCT02265263.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01826-y.

Peripheral interleukin-6-associated microglial QUIN elevation in basolateral amygdala contributed to cognitive dysfunction in a mouse model of postoperative delirium

BACKGROUND

Developing effective approaches for postoperative delirium has been hampered due to the lack of a pathophysiologically similar animal model to offer insights into the pathogenesis. The study, therefore, aimed to develop a delirium-like mouse model and explore the underlying mechanism.

METHODS

The three cycles of 10-min clamp following 5-min reopening of the superior mesenteric artery (SMA) were performed in adult male C57BL/6 mice to induce a delirium-like phenotype. Composite Z score calculated based on the results of Open Field, Y Maze and Buried Food Tests was employed to assess the delirium phenotype in mice. Microglia activities were monitored by immunofluorescence staining and comprehensive morphological analysis. Systemic administration of minocycline (MINO), IL-6 antibody or IL-6 neutralizing antibody, was applied to manipulate microglia. The expressions of Indoleamine 2,3-dioxygenase-1 (IDO-1) and quinolinic acid (QUIN) were examined by RT-PCR and High-Performance Liquid Chromatography/Mass Spectrometry, respectively. Cytokines were measured using fluorescence activated cell sorting method.

RESULTS

The repeated ischemia/reperfusion (I/R) surgery caused significant anxiety (P < 0.05) and cognition decline in working memory and orientation (P < 0.05) in mice at postoperative 24 h. The composite Z score, indicating an overall disturbance of brain function, fluctuated over 24 h after I/R surgery (P < 0.001). Immunofluorescent staining showed that the percentage of microglia in the basolateral amygdala (BLA) (P < 0.05) was reactivated after I/R surgery and was negatively correlated with dwell time at Y maze (R = -0.759, P = 0.035). Inhibiting microglia activities by MINO reduced QUIN productions (P < 0.01) that improved cognitive deficits (P < 0.05). The peripheral IL-6 might cause IL-6 elevation in the BLA. Systemic administration of IL-6 antibodies suppressed I/R-induced IL-6 elevations (P < 0.05), microglial reactivations (P < 0.05), IDO-1 expressions (P < 0.01), and neuroactive metabolite QUIN productions (P < 0.05) in the BLA, resulting in a recovery of cognitive deficits (P < 0.05). Injection of IL-6 exerted opposite effects.

CONCLUSION

The repeated intestinal I/R surgery-induced mouse model is a simple and reproducible one of postoperative delirium. Peripheral IL-6-associated microglial QUIN elevations in the BLA contributed to cognitive dysfunction in the model of postoperative delirium.

Central role of microglia in sepsis-associated encephalopathy: From mechanism to therapy

Sepsis-associated encephalopathy (SAE) is a cognitive impairment associated with sepsis that occurs in the absence of direct infection in the central nervous system or structural brain damage. Microglia are thought to be macrophages of the central nervous system, devouring bits of neuronal cells and dead cells in the brain. They are activated in various ways, and microglia-mediated neuroinflammation is characteristic of central nervous system diseases, including SAE. Here, we systematically described the pathogenesis of SAE and demonstrated that microglia are closely related to the occurrence and development of SAE. Furthermore, we comprehensively discussed the function and phenotype of microglia and summarized their activation mechanism and role in SAE pathogenesis. Finally, this review summarizes recent studies on treating cognitive impairment in SAE by blocking microglial activation and toxic factors produced after activation. We suggest that targeting microglial activation may be a putative treatment for SAE.

Potential Value of Serum Uric Acid in the Identification of Postoperative Delirium in Geriatric Patients Undergoing Knee Replacement

Objectives

The relationship between preoperative serum uric acid (SUA) and cerebrospinal fluid (CSF) Alzheimer-related biomarkers were investigated to determine whether high SUA is a potential risk factor for postoperative delirium (POD) and to evaluate its predictive efficacy.

Methods

The participants were selected from the Perioperative Neurocognitive Disorder Risk Factor and Prognosis (PNDRFAP) study and the Perioperative Neurocognitive Disorder and Biomarker Lifestyle (PNDABLE) study. The logistic regression equation was used to analyze the risk factors and protective factors of POD. The interaction term (SUA × Sex) was introduced into the linear model to explore the potential modification effects of sex on the identified correlations. We analyzed the mediating effects of Alzheimer-related biomarkers. Finally, we constructed the receiver operating characteristic (ROC) curve and the nomogram model to evaluate the efficacy of SUA and Alzheimer-related biomarkers in predicting POD.

Results

Patients with POD had elevated SUA level (PNDRFAP: p = 0.002, PNDABLE: p < 0.001). Preoperative SUA level was positively correlated with CSF phosphorylated tau (P-tau) (p = 0.027) and β-amyloid42 (Aβ₄₂)/P-tau (p = 0.023). Interaction analysis did not find any modification effect of sex. The relationship between SUA and POD was partially mediated by CSF P-tau (15.3%). ROC curve showed that the model combining SUA and Alzheimer-related biomarkers had better performance in predicting POD [area under the curve (AUC) = 0.880; p < 0.001], and the predictive model is accurate.

Conclusions

High SUA may enhance CSF P-tau level, thus increasing the risk of POD, and the model combining SUA and Alzheimer-related biomarkers can accurately predict the occurrence of POD.

Pathogenesis of sepsis-associated encephalopathy: more than blood-brain barrier dysfunction

Sepsis-associated encephalopathy is a common neurological complication of sepsis and is responsible for higher mortality and poorer long-term outcomes in septic patients. Sepsis-associated encephalopathy symptoms can range from mild delirium to deep coma, which occurs in up to 70% of patients in intensive care units. The pathological changes in the brain associated with sepsis include cerebral ischaemia, cerebral haemorrhage, abscess and progressive multifocal necrotic leukoencephalopathy. Several mechanisms are involved in the pathogenesis of sepsis-associated encephalopathy, such as blood-brain barrier dysfunction, cerebral blood flow impairment, glial cell activation, leukocyte transmigration, and neurotransmitter disturbances. These events are interrelated and influence each other, therefore they do not act as independent factors. This review is focused on new evidence showing the pathological process of sepsis-associated encephalopathy.

Persistent viral RNA shedding of SARS-CoV-2 is associated with delirium incidence and six-month mortality in hospitalized COVID-19 patients

BACKGROUND

Persistent viral RNA shedding of SARS-CoV-2 following COVID-19 has increasingly been recognized, with limited understanding of its implications on outcomes in hospitalized COVID-19 patients.

METHODS

We retrospectively assessed for persistent viral shedding across Northwestern Medicine Healthcare (NMHC) patients between March and August 2020. We assessed for predictors of persistent viral shedding, in-hospital delirium, and six-month mortality using binary logistic regression.

RESULTS

Of the 2,518 hospitalized patients with an RT-PCR-confirmed diagnosis of COVID-19, 959 underwent repeat SARS-CoV-2 RT-PCR at least fourteen days from initial positive testing. Of those, 405 (42.2%) patients were found to have persistent viral shedding. Persistent viral shedding was associated with male sex, increased BMI, diabetes mellitus, chronic kidney disease, and exposure to corticosteroids during initial COVID-19 hospitalization. Persistent viral shedding was independently associated with incidence of in-hospital delirium after adjusting for factors including severity of respiratory dysfunction (OR 2.45; 95% CI 1.75, 3.45). Even after adjusting for age, severity of respiratory dysfunction, and occurrence of in-hospital delirium, persistent viral shedding remained significantly associated with increased six-month mortality (OR 2.43; 95% CI 1.42, 4.29).

CONCLUSIONS

Persistent viral shedding occurs frequently in hospitalized COVID-19 patients and is associated with in-hospital delirium and increased six-month mortality.

A case for continuing statin medications in the intensive care unit: Reducing the risk for delirium

DISCLAIMER

In an effort to expedite the publication of articles related to the COVID-19 pandemic, AJHP is posting these manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

The objective of this review is to detail the utility of statin medications in the prevention and treatment of intensive care unit (ICU) delirium.

SUMMARY

Delirium is a syndrome characterized by altered mental status, inattention, and disorganized thinking. It is particularly concerning in the ICU where specific risk factors are much more prevalent. Nonpharmacological therapy is the mainstay of treatment, aimed at increasing patient awareness; pharmacological therapies have also been explored with varying success. The utility of statin medications in this scenario has been investigated because of the numerous pleiotropic effects of these drugs. Although the benefits in terms of treating delirium are uncertain, statins may be good candidates for prevention. The peak anti-inflammatory effect of statins is delayed, so initiating a statin on admission will likely have little protective benefit, whereas continuation of a home regimen seems more likely to exert an effect.

CONCLUSION

Statin medications are very commonly used, and, while their role in treating delirium is unclear, continuation of these medications from a home regimen is reasonable to decrease the odds of delirium in the intensive care population.

Sepsis-associated brain injury: underlying mechanisms and potential therapeutic strategies for acute and long-term cognitive impairments

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Sepsis causes cerebral dysfunction in the short and long term and induces disruption of the blood–brain barrier (BBB), neuroinflammation, hypoperfusion, and accumulation of amyloid β (Aβ) and tau protein in the brain. White matter changes and brain atrophy can be detected using brain imaging, but unfortunately, there is no specific treatment that directly addresses the underlying mechanisms of cognitive impairments in sepsis. Here, we review the underlying mechanisms of sepsis-associated brain injury, with a focus on BBB dysfunction and Aβ and tau protein accumulation in the brain. We also describe the neurological manifestations and imaging findings of sepsis-associated brain injury, and finally, we propose potential therapeutic strategies for acute and long-term cognitive impairments associated with sepsis. In the acute phase of sepsis, we suggest using antibiotics (such as rifampicin), targeting proinflammatory cytokines, and preventing ischemic injuries and hypoperfusion. In the late phase of sepsis, we suggest targeting neuroinflammation, BBB dysfunction, Aβ and tau protein phosphorylation, glycogen synthase kinase-3 beta (GSK3β), and the receptor for advanced glycation end products (RAGE). These proposed strategies are meant to bring new mechanism-based directions for future basic and clinical research aimed at preventing or ameliorating acute and long-term cognitive impairments in patients with sepsis.

Microglial cell response in α7 nicotinic acetylcholine receptor-deficient mice after systemic infection with Escherichia coli

Background

Development of neurodegeneration in older people has been associated with microglial cell activation triggered by systemic infection. We hypothesize that α7 nicotinic acetylcholine receptor (α7nAChR) plays an important role in regulation of this process.

Methods

8- to 10-week-old male wild-type (WT) and α7nAChR knock-out (α7nAChR^−/−) mice were intraperitoneally inoculated with live Escherichia (E.) coli or saline. After inoculation, all mice were treated with ceftriaxone (an antimicrobial drug) at 12 and 24 h and killed at 2 or 3 days. The microglial response was characterized by immunohistochemical staining with an ionized calcium-binding adaptor molecule 1 (Iba-1) antibody and flow cytometry. To quantify inflammatory response, mRNA expression of pro- and anti-inflammatory mediators was measured in brain and spleen.

Results

We observed no differences in Iba-1 positive cell number or morphology and flow cytometry (CD11b, CD45 and CD14) of microglial cells between WT and α7nAChR^−/− mice after systemic infection. Infected α7nAChR^−/− mice showed significantly higher mRNA expression in brain for tumor necrosis factor alpha (TNF-α) at day 2 and 3, interleukin 6 (IL-6) at day 2 and monocyte chemotactic protein 1 (MCP-1) and suppressor of cytokine signaling 1 (SOCS1) at day 3, there was significantly lower mRNA expression in brain for mitogen-activated protein kinase 1 (MAPK1) at day 2 and 3, high-mobility group 1 (HMGB-1) and CD11b at day 2, and deubiquitinase protein A20 (A20) at day 3 compared to infected WT mice.

Interpretation

Loss of function of α7nAChR during systemic infection led to an increased expression of TNF-α and IL-6 in brain after systemic infection with E. coli, but not to distinct differences in microglial cell number or morphological activation of microglia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02452-8.

Real-World Evidence for the Association Between Pneumonia-Related Intensive Care Unit Stay and Dementia

OBJECTIVE

There is limited clarity concerning the risk of dementia after pneumonia with intensive care unit (ICU) stay. We conducted a nationwide cohort study, which aimed to investigate the impact of dementia after pneumonia with and without intensive care unit admission.

METHODS

Data was obtained from Taiwan's National Health Insurance Research Database between 2000 and 2015. A total of 7,473 patients were identified as having pneumonia required ICU stay, along with 22,419 controls matched by sex and age. After adjusting for confounding factors, multivariate Cox regression model analysis was used to compare the risk of developing dementia during the 15-years follow-up period.

RESULTS

The enrolled pneumonia patients with ICU admission had a dementia rate of 9.89%. Pneumonia patients without ICU admission had a dementia rate of 9.21%. The multivariate Cox regression model analysis revealed that the patients with ICU stay had the higher risk of dementia, with a crude hazard ratio of 3.371 (95% confidence interval, 3.093-3.675; p<0.001).

CONCLUSION

This study indicated that pneumonia with ICU stay is associated with an increased risk of dementia. A 3-fold risk of dementia was observed in patients admitted to the ICU compared to the control group.

Insight Into Regulatory T Cells in Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy (SAE) is a diffuse central nervous system (CNS) dysfunction during sepsis, and is associated with increased mortality and poor outcomes in septic patients. Despite the high incidence and clinical relevance, the exact mechanisms driving SAE pathogenesis are not yet fully understood, and no specific therapeutic strategies are available. Regulatory T cells (T_regs) have a role in SAE pathogenesis, thought to be related with alleviation of sepsis-induced hyper-inflammation and immune responses, promotion of T helper (Th) 2 cells functional shift, neuroinflammation resolution, improvement of the blood-brain barrier (BBB) function, among others. Moreover, in a clinical point of view, these cells have the potential value of improving neurological and psychiatric/mental symptoms in SAE patients. This review aims to provide a general overview of SAE from its initial clinical presentation to long-term cognitive impairment and summarizes the main features of its pathogenesis. Additionally, a detailed overview on the main mechanisms by which T_regs may impact SAE pathogenesis is given. Finally, and considering that T_regs may be a novel target for immunomodulatory intervention in SAE, different therapeutic options, aiming to boost peripheral and brain infiltration of T_regs, are discussed.

Exosome-Derived lncRNA NEAT1 Exacerbates Sepsis-Associated Encephalopathy by Promoting Ferroptosis Through Regulating miR-9-5p/TFRC and GOT1 Axis

Sepsis can cause sepsis-associated encephalopathy (SAE), but whether SAE was induced or exacerbated by ferroptosis remains unknown. In this study, the rat sepsis model was constructed using the cecal ligation and puncture method. The blood-brain barrier (BBB) permeability was measured by Evans blue dye (EBD) in vivo. The levels of ROS, Fe ion, MDA, GSH, and GPX4 were assessed by enzyme-linked immunosorbent assay (ELISA). The exosomes isolated from serum were cultured with bEnd.3 cells for the in vitro analysis. Moreover, bEnd.3 cells cultured with 100 μM FeCl3 (iron-rich) were to simulate ferroptosis stress. The cell viability was evaluated by Cell Counting Kit-8 (CCK-8) assay. A dual-luciferase reporter gene assay was performed to confirm the relationship between miR-9-5p with NEAT1, TFRC, and GOT1. In vivo, it is found that BBB permeability was damaged in model rats. Level of ROS, Fe ion, and MDA was increased, and level of GSH and GPX4 was decreased, which means ferroptosis was induced by sepsis. Exosome-packaged NEAT1 in serum was significantly upregulated in model rats. In vitro, it is found that NEAT1 functions as a ceRNA for miR-9-5p to facilitate TFRC and GOT1 expression. Overexpression of NEAT1 enhanced ferroptosis stress in bEnd.3 cells. Increased miR-9-5p alleviated sepsis-induced ferroptosis by suppressing the expression of TFRC and GOT1 both in vivo and in vitro. In conclusion, these findings suggest that sepsis induced high expression of serous exosome-derived NEAT1, and it might exacerbate SAE by promoting ferroptosis through regulating miR-9-5p/TFRC and GOT1 axis.

Emerging Knowledge of the Neurobiology of COVID-19

Many patients with COVID-19 will experience acute or longer-term neuropsychiatric complications. The neurobiological mechanisms behind these are beginning to emerge; however, the neurotropic hypothesis is not strongly supported by clinical data. The inflammatory response to SARS-CoV-2 is likely to be responsible for delirium and other common acute neuropsychiatric manifestations. Vascular abnormalities such as endotheliopathies contribute to stroke and cerebral microbleeds, with their attendant neuropsychiatric sequelae. Longer-term neuropsychiatric syndromes fall into 2 broad categories: neuropsychiatric deficits occurring after severe (hospitalized) COVID-19 and "long COVID," which occurs in many patients with a milder acute COVID-19 illness.

Emerging Trends and Hot Spots in Sepsis-Associated Encephalopathy Research From 2001 to 2021: A Bibliometric Analysis

Study Objectives

To evaluate sepsis-associated encephalopathy (SAE) research and to quantitatively and qualitatively predict research hot spots using bibliometric analysis.

Methods

We extracted relevant publications from the Web of Science Core Collection on July 28, 2021. We investigated the retrieved data by bibliometric analysis (e.g. co-cited and cluster analysis, keyword co-occurrence) using the software CiteSpace and VOSviewer, the Online Analysis Platform of Literature Metrology (http://bibliometric.com/) and Bibliometrix to analyse and predict the trends and hot spots in this field.

Main Results

We identified 1,582 published articles and reviews on SAE from 2001 to 2021. During this period, the number of manuscripts on SAE increased steadily and peaked in 2021. The USA and China were the leading countries that had a critical impact on SAE research. Among all institutions, Vanderbilt University and Pittsburgh University held leading positions and became central in the collaboration network. Among all the journals, Critical Care Medicine published the maximum number of manuscripts in the field of SAE within 20 years. Dal-Pizzol Felipe was the most productive author (61 papers) and received the largest number of citations (930 citations). Co-citation cluster analysis revealed that the most popular terms on SAE in the manner of cluster labels were critical illness, sepsis-associated encephalopathy, polymicrobial sepsis, posterior reversible encephalopathy syndrome, rat brain, intensive care unit, prior sepsis, molecular hydrogen, inflammation drive, metabolic encephalopathies, delirium pathophysiology, and clinical neuroscience. Keyword burst detection indicated that neuroinflammation, blood-brain barrier (BBB) and mitochondria dysfunction were the current research hot spots.

Conclusions

Our study revealed that neuroinflammation, blood-brain barrier, and mitochondria dysfunction had been the research foci of SAE over the past 20 years. These have emerged as the basis for transformation from basic research to clinical application in finding effective methods for the prevention and treatment of SAE.

The protective effects of Mirtazapine against lipopolysaccharide (LPS)-induced brain vascular hyperpermeability

Sepsis is mainly characterized by severe inflammation triggered by infection, and sepsis-associated encephalopathy (SAE) is defined as brain damage caused by sepsis. Disruption of the blood-brain barrier (BBB) triggered by injured brain microvascular endothelial cells (BMECs) and damaged tight junction (TJ) structure is closely associated with the pathogenesis of SAE. The present research proposed to evaluate the potential therapeutic effects of Mirtazapine, a central presynaptic α2 receptor antagonist, on LPS-induced BBB disruption. The mice were administered with normal saline and 10 mg/kg Mirtazapine for 8 consecutive days, and from day 6, the experiment group of mice received LPS for 2 days to induce SAE. We found that the increased BBB permeability, elevated concentrations of inflammatory factors in brain tissues, and downregulated zonula occludens -1 (ZO-1) were observed in LPS-stimulated mice, all of which were reversed by 10 mg/kg Mirtazapine. In the in vitro assay, bEnd.3 brain endothelial cells were treated with 1 μM LPS in the absence or presence of Mirtazapine (25, 50 μM). We found that LPS-treated cells had significantly declined transendothelial electrical resistance (TEER), increased monolayer permeability, elevated production of inflammatory factors, and downregulated ZO-1. However, 25 and 50 μM Mirtazapine ameliorated all these LPS- induced aberrations. Mirtazapine also mitigated the decreased level of NF-E2-related factor 2 (Nrf2) in LPS-challenged endothelial cells. The protective effect of Mirtazapine on endothelial permeability against LPS was significantly abolished by the knockdown of Nrf2. Collectively, we concluded that Mirtazapine exerted protective effects on LPS-induced endothelial cells hyperpermeability by upregulating Nrf2.

[Light Therapy for Prevention of Delirium in Critically Ill Patients: What's the Evidence?]

Circadian dysrhythmia affects the majority of ICU patients and has far-reaching effects on organ functioning. At the level of the central nervous system, circadian misalignment facilitates executive cognitive dysfunction and the development of ICU delirium. The pathophysiological mechanisms, especially in the cohort of critically ill patients, appear to be complex, multilayered and far from understood. Results from preliminary research indicate that multidimensional, patient-specific chronotherapeutic concepts developed specifically for the ICU setting may help improve the healing process of patients. Circadian lighting therapy might be a promising intervention in this context.

Commonly expressed key transcriptomic profiles of sepsis in the human circulation and brain via integrated analysis

BACKGROUND

Sepsis is the leading cause of death in intensive care units and is characterized by multiple organ failure, including dysfuction of the immune system and brain. This study aims to determine the differential effect of sepsis on specific circulating immune cell subsets compared with brain transcriptome and identify the genes co-expressed by them, so as to identify key genes and regulatory factors involved in the pathogenesis of sepsis induced brain injury and identify novel therapeutic targets.

METHODS

The GSE133822 and GSE135838 datasets were obtained from the Gene Expression Omnibus (GEO) database and utilized for bioinformatics analyses. Functional enrichment analysis was used to identify commonly expressed genes that were differentially expressed between sepsis patients and non-sepsis patients with critical illness; protein-protein interaction (PPI) networks were also generated. Then, key transcriptomic biomarkers were further validated in an external dataset from the GEO. We also investigated the expression of key mRNAs in peripheral blood mononuclear cells (PBMCs) from sepsis patients by quantitative PCR (qPCR) and an in-vitro model stimulated by lipopolysaccharide (LPS) was generated in brain cell lines.

RESULTS

The transcriptomic profiles of brain tissue were relatively similar as those of specific immune cells. In addition, our validation showed that these key genes were up regulated both in PBMCs in sepsis patients and LPS-treated brain cells.

CONCLUSION

Brain injury in sepsis was correlated with circulating immune responses, and the expression of DEFA3, MMP8, MMP9 and LCN2 might be potential diagnostic biomarkers as well as therapeutic target in septic brain dysfunction.

Utility of white matter disease and atrophy on routinely acquired brain imaging for prediction of long-term delirium risk: population-based cohort study

Background

brain imaging done as part of standard care may have clinical utility beyond its immediate indication. Using delirium as an exemplar, we determined the predictive value of baseline brain imaging variables [white matter changes (WMC) and atrophy] for delirium risk on long-term follow-up after transient ischemic attack (TIA)/stroke in a population-based cohort study.

Methods

surviving TIA/stroke participants in the Oxford Vascular Study (OXVASC) were assessed prospectively for delirium during all hospitalisations over 6 months (2013–14). Using logistic regression, independent associations were determined between baseline OXVASC computed tomography or magnetic resonance brain imaging measures of WMC and cerebral atrophy (none/mild versus moderate/severe) and delirium adjusted for age, sex, baseline stroke severity, depression, illness severity and pre-admission cognition.

Results

among 1,565 TIA/stroke survivors with 194 hospital admissions (158 patients, mean/standard deviation age at admission = 79.2/11.5 years), delirium occurred in 59 (37%). WMC and atrophy on baseline imaging were associated with delirium [odds ratio (OR) = 3.41, 1.21–5.85, P = 0.001 and OR = 2.50, 1.23–5.08, P = 0.01 (unadjusted) and OR = 2.67, 1.21–5.85, P = 0.02 and OR = 2.18, 1.00–4.73, P = 0.05 (adjusted age and sex)]. Associations were strengthened when analyses were restricted to patients hospitalised within 5 years of baseline brain imaging [OR = 6.04, 2.39–15.24, P < 0.0001 and OR = 4.64, 1.46–14.82, P = 0.009 (unadjusted)] but only WMC remained significant after adjustment for all covariates including pre-admission cognition (OR = 4.83, 1.29–18.13, P = 0.02 for Mini-Mental State Examination and OR = 5.15, 1.26–21.09, P = 0.02 for Montreal Cognitive Assessment).

Conclusions

WMC and atrophy on brain imaging done up to 5 years earlier predicted delirium and may have clinical utility in risk stratification. Associations with WMC but not atrophy were independent of pre-admission cognitive impairment.

Bibliometric Analysis of 100 Most-Cited Articles in Delirium

Delirium is a cognitive disorder with complex etiology, which brings a great burden to social health care. Articles with high citation frequency can provide important information about the current research situation in a certain field. Web of Science was used to search the 100 most-cited articles and we extracted key information, such as the authors, countries/regions, institutions, journals, and study types of these articles. CiteSpace was used to visually analyze the keywords. Our bibliometric analysis shows that the attention in this field continues to rise. Authors from the United States published the most articles and Inouye SK is the most influential author in the field. The journals that published these articles have high impact factors. Cohort studies are the main cited articles in this field, and there are a large number of systematic reviews or meta-analyses of cohort studies. Risk factors for delirium, psychometric evaluation, hospital care, and various clinical study design are still the focus of research. In short, we summarized the 100 most-cited articles in the field of delirium to identify the current status and global trends. These results enable researchers to understand the quality and trend of research in the field of delirium and make better use of the classical literature.

Inclusion of interleukin-6 improved performance of postoperative delirium prediction for patients undergoing coronary artery bypass graft (POD-CABG): A derivation and validation study

BACKGROUND

Patients undergoing coronary artery bypass graft (CABG) are at high risk for developing postoperative delirium (POD). A simple prediction rule may benefit patients from early identification of POD followed by adequate preventive strategies. The purpose of the current study was to develop and validate a POD prediction rule for patients undergoing CABG (POD-CABG), by considering all possible perioperative factors.

METHODS

In this prospective cohort study, patients who underwent first elective isolated CABG were continuously enrolled from May 2014 to November 2015 in a tertiary hospital. Delirium was assessed using the Confusion Assessment Method for Intensive Care Unit. Patients' perioperative risk factors were collected through interviews and review of medical records. The area under receiver-operating characteristic curve (AUC) was used to assess the overall performance of the predictive rule.

RESULTS

A total of 242 and 148 patients were enrolled in the derivation and validation cohorts, respectively. Multiple logistic regression analysis identified seven variables that were independently associated with POD: age (≥65 years), gender (female), history of myocardial infarction and diabetes mellitus, postoperative atrial fibrillation, the use of intra-aortic balloon pump, and serum interleukin-6 ≥478 pg/ml at 18 hours after surgery. The AUC of the POD-CABG was 0.84 (95% CI, 0.79-0.90) in the derivation cohort, and was 0.86 (95% CI, 0.80-0.91) after bootstrap resampling. The AUC was 0.81 (95% CI, 0.73-0.88) after the POD-CABG was applied to the validation cohort.

CONCLUSIONS

The POD-CABG with inclusion of interleukin-6 demonstrated good performance in predicting POD.

Relationship Between Cerebral Hemodynamics, Tissue Oxygen Saturation, and Delirium in Patients With Septic Shock: A Pilot Observational Cohort Study

Background: Septic shock patients have tendencies toward impairment in cerebral autoregulation and imbalanced cerebral oxygen metabolism. Tissue Oxygen Saturation (StO₂) and Transcranial Doppler (TCD) monitoring were undertaken to observe the variations of cerebral hemodynamic indices and cerebral/peripheral StO₂ to find risk factors that increase the sepsis-associated delirium (SAD). Materials and Methods: The research cohort was chosen from septic shock patients received in the Department of Critical Care Medicine, Xiangya Hospital, Central South University between May 2018 and March 2019. These patients were separated into two groups, SAD and non-SAD as assessed by using the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU). Comparisons were made between the two groups in terms of peripheral StO₂, fluctuations in regional cerebral oxygen saturation (rSO₂), cerebral vascular automatic regulation function [Transient Hyperemic Response Ratio (THRR) index], cerebral hemodynamic index, organ function indicators, blood gas analysis indices, and patient characteristics. Results: About 39% of the patients (20/51) suffered from SAD. Nearly 43% of the patients died within 28 days of admission (22/51). Individuals in the SAD cohort needed a longer period of mechanical ventilation [5 (95% CI 2, 6) vs. 1 days (95% CI 1, 4), p = 0.015] and more time in ICU [9 (95% CI 5, 20) vs. 5 days (95% CI 3, 9), p = 0.042]; they also experienced more deaths over the 28-day period (65 vs. 29%, p = 0.011). The multivariate regression analysis indicated that independent variables associated with SAD were THRR index [odds ratio (OR) = 5.770, 95% CI: 1.222-27.255; p = 0.027] and the mean value for rSO₂ was < 55% (OR = 3.864, 95% CI: 1.026-14.550; p = 0.046). Conclusion: Independent risk factors for SAD were mean cerebral oxygen saturation below 55% and cerebrovascular dysregulation (THRR < 1.09).

ICU delirium burden predicts functional neurologic outcomes

Background

We investigated the effect of delirium burden in mechanically ventilated patients, beginning in the ICU and continuing throughout hospitalization, on functional neurologic outcomes up to 2.5 years following critical illness.

Methods

Prospective cohort study of enrolling 178 consecutive mechanically ventilated adult medical and surgical ICU patients between October 2013 and May 2016. Altogether, patients were assessed daily for delirium 2941days using the Confusion Assessment Method for the ICU (CAM-ICU). Hospitalization delirium burden (DB) was quantified as number of hospital days with delirium divided by total days at risk. Survival status up to 2.5 years and neurologic outcomes using the Glasgow Outcome Scale were recorded at discharge 3, 6, and 12 months post-discharge.

Results

Of 178 patients, 19 (10.7%) were excluded from outcome analyses due to persistent coma. Among the remaining 159, 123 (77.4%) experienced delirium. DB was independently associated with >4-fold increased mortality at 2.5 years following ICU admission (adjusted hazard ratio [aHR], 4.77; 95% CI, 2.10–10.83; P < .001), and worse neurologic outcome at discharge (adjusted odds ratio [aOR], 0.02; 0.01–0.09; P < .001), 3 (aOR, 0.11; 0.04–0.31; P < .001), 6 (aOR, 0.10; 0.04–0.29; P < .001), and 12 months (aOR, 0.19; 0.07–0.52; P = .001). DB in the ICU alone was not associated with mortality (HR, 1.79; 0.93–3.44; P = .082) and predicted neurologic outcome less strongly than entire hospital stay DB. Similarly, the number of delirium days in the ICU and for whole hospitalization were not associated with mortality (HR, 1.00; 0.93–1.08; P = .917 and HR, 0.98; 0.94–1.03, P = .535) nor with neurological outcomes, except for the association between ICU delirium days and neurological outcome at discharge (OR, 0.90; 0.81–0.99, P = .038).

Conclusions

Delirium burden throughout hospitalization independently predicts long term neurologic outcomes and death up to 2.5 years after critical illness, and is more predictive than delirium burden in the ICU alone and number of delirium days.

Cognitive Predictors of Delirium on Long-Term Follow-Up after TIA and Stroke: Population-Based Cohort Study

INTRODUCTION

TIA and stroke cause cognitive impairment with a typical "vascular" pattern, including prominent frontal/executive deficits. Cognitive impairment is associated with increased delirium risk and the few available data suggest that executive dysfunction is important. We therefore determined the predictive value of both severity and pattern of cognitive deficits for delirium on long-term follow-up after TIA/stroke.

METHODS

Surviving TIA/stroke participants on October 1, 2013, in the Oxford Vascular Study (OXVASC) were assessed prospectively for delirium during all hospitalizations over the subsequent 6 months. Associations between OXVASC pre-admission mini-mental state examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores, and delirium during hospitalizations on follow-up were determined using logistic regression adjusted for covariates, including demographic factors, history of depression, baseline stroke severity, and admission illness severity.

RESULTS

Among 1,565 TIA/stroke survivors, 158 patients (mean/SD age = 79.2/11.5 years) had ≥1 admission and 59 (37%) had ≥1 delirium episode. Mean/SD time between baseline TIA/stroke and admission was 4.7/3.6 years and between most recent OXVASC cognitive testing and admission was 1.7/1.8 years. MMSE and MoCA scores were associated with delirium: odds ratio (OR) = 1.16 (95% CI 1.07-1.27, p < 0.0001 per point decrease in MMSE) and OR = 1.20 (1.11-1.30, p < 0.0001 MoCA) and associations were robust to adjustment for all covariates, including stroke severity: OR = 1.11 (1.01-1.22, p = 0.03, MMSE) and OR = 1.15 (1.05-1.25, p = 0.003, MoCA). All 10 subtests on the MoCA and 4/11 on the MMSE were significantly associated with delirium with highest predictive value for frontal/executive and recall domains.

CONCLUSIONS

Cognitive impairment of increasing severity after TIA/stroke predisposed to delirium particularly deficits in frontal/executive domains and recall. Long-term risk of delirium should be considered as part of the overall cerebrovascular disease burden.

Alterations in T-Cell Transcription Factors and Cytokine Gene Expression in Late-Onset Alzheimer's Disease

BACKGROUND

Late-onset Alzheimer's disease (LOAD) is associated with many environmental and genetic factors. The effect of systemic inflammation on the pathogenesis of neurodegenerative diseases such as AD has been strongly suggested. T helper cells (Th) are one of the important components of the immune system and can easily infiltrate the brain in pathological conditions. The development of each Th-subset depends on the production of unique cytokines and their main regulator.

OBJECTIVE

This study aimed to compare the mRNA levels of Th-related genes derived from peripheral blood mononuclear cells of LOAD patients with control. Also, the identification of the most important Th1/Th2 genes and downstream pathways that may be involved in the pathogenesis of AD was followed by computational approaches.

METHODS

This study invloved 30 patients with LOAD and 30 non-demented controls. The relative expression of T-cell cytokines (IFN-γ, TNF-α, IL-4, and IL-5) and transcription factors (T-bet and GATA-3) were assessed using real-time PCR. Additionally, protein-protein interaction (PPI) was investigated by gene network construction.

RESULTS

A significant decrease at T-bet, IFN-γ, TNF-α, and GATA-3 mRNA levels was detected in the LOAD group, compared to the controls. However, there was no significant difference in IL-4 or IL-5 mRNA levels. Network analysis revealed a list of the highly connected protein (hubs) related to mitogen-activated protein kinase (MAPK) signaling and Th17 cell differentiation pathways.

CONCLUSION

The findings point to a molecular dysregulation in Th-related genes, which can promising in the early diagnosis or targeted interventions of AD. Furthermore, the PPI analysis showed that upstream off-target stimulation may involve MAPK cascade activation and Th17 axis induction.