Cerebrospinal fluid catecholamines in delirium and dementia

Liquid chromatography-tandem mass spectrometry assay for simultaneous quantification of catecholamines and metabolites in human plasma and cerebrospinal fluid

Catecholamines (CAs) and their metabolites in human cerebrospinal fluid (CSF) and plasma are potential biomarkers of Alzheimer's disease (AD) and facilitate early diagnosis. Liquid chromatography-tandem mass spectrometry is the gold standard method for analyzing CAs. The objective of this study was to develop and validate a liquid chromatography-tandem mass spectrometry assay capable of simultaneously quantifying dopamine (DA), epinephrine (E), norepinephrine (NE), metanephrine (MN), normetanephrine (NMN), and 3-methoxytyramine (3-MT) in both human CSF and plasma. Samples were processed by solid-phase extraction with a weak cation exchange adsorbent and then separated using an ultra-performance reversed-phase chromatography column. Analyte detection was performed using a triple quadrupole mass spectrometer operated in positive-ion multiple reaction monitoring mode. The developed assay was validated according to standard guidelines. The linearity, specificity, precision, accuracy, carryover and stability were assessed to ensure compliance with specified criteria. The lower limits of quantification for DA, E, NE, MN, NMN, and 3-MT were 4.5, 2.5, 4.5, 2.5, 2, and 0.3 pg mL-1, respectively. The total runtime for a single sample was 6.5 min. These results demonstrated that the method was sensitive, rapid, and reliable for the simultaneous quantification of DA, E, NE, MN, NMN, and 3-MT in clinical practice. We successfully detected CAs and their metabolites in plasma and CSF samples from patients with normal cognition and AD. This study demonstrates an efficient laboratory workflow for high-throughput analysis of CAs and their metabolites and lays a foundation for further studies on AD biomarkers.

Photoelectrochemical biosensor with single atom sites for norepinephrine sensing and brain region synergy in epilepsy

Norepinephrine (NE), a pivotal neurotransmitter in the central and sympathetic nervous systems, is crucial for numerous physiological and pathophysiological processes. Distinguishing NE from structurally similar dopamine and epinephrine in complex in vivo environments is a significant challenge. Herein, we propose a molecular docking strategy for selective, sensitive, and ultrafast detection of NE in vivo. Leveraging the molecular structure of NE, we design a Zn single-atom-modified TiO2 substrate (Zn1/TiO2) as a photoelectrochemical (PEC) biosensor, providing synergistic atomic anchoring sites to "lock" NE molecules and enabling real-time NE detection in the brain of living male mice with a response time of 60 ms. The high specificity and rapid detection capabilities of this biosensor have unveiled a regulatory mechanism of the noradrenergic system across multiple brain regions, including the locus coeruleus, cortex, and hippocampus, highlighting a synergistic effect during epilepsy. This rationally designed single-atomic PEC biosensor for in situ monitoring of neurotransmitter dynamics holds promise for future brain science research.

Initial dose of tapentadol and concomitant use of duloxetine are associated with delirium occurring after initiation of tapentadol therapy in cancer patients

OBJECTIVE

Tapentadol causes fewer gastrointestinal adverse events than other potent opioid analgesics because of its low affinity for opioid receptors; however, development of symptoms related to central nervous system disorders, including delirium, has not been well-studied. This study aimed to identify the factors that influence the development of delirium after initiation of tapentadol therapy in hospitalized patients with cancer.

DESIGN

Retrospective study.

SETTING/PATIENTS

Among 93 patients, for whom treatment using tapentadol was initiated between December 1, 2017, and November 30, 2019, at a single center in Japan, 86 met the inclusion criteria and were enrolled in this study.

MAIN OUTCOME MEASURES

Delirium occurring within 2 weeks of initiation of the tapentadol treatment was diagnosed by a physician or nurse. Patient background information was obtained, including data on age, sex, medical history, adverse events, starting dose of tapentadol, and concomitant medications.

RESULTS

Age ≥ 67 years, male sex, somnolence after initiation of tapentadol therapy, dose of ≥300 mg/day at the beginning of tapentadol therapy, switching from potent opioids, and concomitant use of duloxetine were associated with delirium occurring after tapentadol therapy initiation.

CONCLUSIONS

Among the factors associated with the incidence of delirium after the initiation of tapentadol therapy, patients whose starting dose of tapentadol was 300 mg/day or higher and those receiving concomitant duloxetine, a serotonin-noradrenaline reuptake inhibitor, were at high risk of developing delirium. These findings will help healthcare providers, including pharmacists, in development of treatment plans for preventing delirium when initiating tapentadol therapy in patients with cancer.

Mechanisms underlying delirium in patients with critical illness

Delirium is an acute, global cognitive disorder syndrome, also known as acute brain syndrome, characterized by disturbance of attention and awareness and fluctuation of symptoms. Its incidence is high among critically ill patients. Once patients develop delirium, it increases the risk of unplanned extubation, prolongs hospital stay, increases the risk of nosocomial infection, post-intensive care syndrome-cognitive impairment, and even death. Therefore, it is of great importance to understand how delirium occurs and to reduce the incidence of delirium in critically ill patients. This paper reviews the potential pathophysiological mechanisms of delirium in critically ill patients, with the aim of better understanding its pathophysiological processes, guiding the formulation of effective prevention and treatment strategies, providing a basis for clinical medication.

Preclinical and translational models for delirium: Recommendations for future research from the NIDUS delirium network

Delirium is a common, morbid, and costly syndrome that is closely linked to Alzheimer's disease (AD) and AD-related dementias (ADRD) as a risk factor and outcome. Human studies of delirium have advanced our knowledge of delirium incidence and prevalence, risk factors, biomarkers, outcomes, prevention, and management. However, understanding of delirium neurobiology remains limited. Preclinical and translational models for delirium, while challenging to develop, could advance our knowledge of delirium neurobiology and inform the development of new prevention and treatment approaches. We discuss the use of preclinical and translational animal models in delirium, focusing on (1) a review of current animal models, (2) challenges and strategies for replicating elements of human delirium in animals, and (3) the utility of biofluid, neurophysiology, and neuroimaging translational markers in animals. We conclude with recommendations for the development and validation of preclinical and translational models for delirium, with the goal of advancing awareness in this important field.

Cerebrospinal fluid catecholamines in Alzheimer's disease patients with and without biological disease

Noradrenergic and dopaminergic neurons are involved in cognitive functions, relate to behavioral and psychological symptoms in dementia and are affected in Alzheimer's disease (AD). Amyloid plaques (A), neurofibrillary tangles (T) and neurodegeneration (N) hallmarks the AD neuropathology. Today, the AT(N) pathophysiology can be assessed through biomarkers. Previous studies report cerebrospinal fluid (CSF) catecholamine concentrations in AD patients without biomarker refinement. We explored if CSF catecholamines relate to AD clinical presentation or neuropathology as reflected by CSF biomarkers. CSF catecholamines were analyzed in AD patients at the mild cognitive impairment (MCI; n = 54) or dementia stage (n = 240) and in cognitively unimpaired (n = 113). CSF biomarkers determined AT status and indicated synaptic damage (neurogranin). The AD patients (n = 294) had higher CSF noradrenaline and adrenaline concentrations, but lower dopamine concentrations compared to the cognitively unimpaired (n = 113). AD patients in the MCI and dementia stage of the disease had similar CSF catecholamine concentrations. In the CSF neurogranin positively associated with noradrenaline and adrenaline but not with dopamine. Adjusted regression analyses including AT status, CSF neurogranin, age, gender, and APOEε4 status verified the findings. In restricted analyses comparing A+T+ patients to A-T- cognitively unimpaired, the findings for CSF adrenaline remained significant (p < 0.001) but not for CSF noradrenaline (p = 0.07) and CSF dopamine (p = 0.33). There were no differences between A+T+ and A-T- cognitively unimpaired. Thus, we find alterations in CSF catecholamines in symptomatic AD and the CSF adrenergic transmitters to increase simultaneously with synaptic damage as indexed by CSF neurogranin.

The Locus Coeruleus Noradrenaline System in Delirium

Delirium is a brain state involving severe brain dysfunction affecting cognitive and attentional capacities. Our opinion statement review aims to elucidate the relationship between abnormal arousal and locus coeruleus (LC) activity in cognitive dysfunction and inattention in delirium states. We propose (1) that enhanced noradrenaline release caused by altered arousal in hyperactive delirium states leads to increased noradrenergic transmission within the LC and subcortical and cortical brain regions including the prefrontal cortex and hippocampus, thus affecting how attention and cognition function. In hypoactive delirium states, however, we are presuming (2) that less arousal will cause the release of noradrenaline to diminish in the LC, followed by reduced noradrenergic transmission in cortical and subcortical brain areas concentrated within the prefrontal cortex and hippocampus, leading to deficient attention and cognitive processing. Studies addressing the measurement of noradrenaline and its derivatives in biomaterial probes regarding delirium are also covered in this article. In conclusion, the LC-NA system plays a crucial role in generating delirium. Yet there have been no large-scale studies investigating biomarkers of noradrenaline to help us draw conclusions for improving delirium's diagnosis, treatment, and prognosis, and to better understand its pathogenesis.