Salivary Cortisol Concentrations Research Articles

Utilizing Machine Learning for Context-Aware Digital Biomarker of Stress in Older Adults

Identifying stress in older adults is a crucial field of research in health and well-being. This allows us to take timely preventive measures that can help save lives. That is why a nonobtrusive way of accurate and precise stress detection is necessary. Researchers have proposed many statistical measurements to associate stress with sensor readings from digital biomarkers. With the recent progress of Artificial Intelligence in the healthcare domain, the application of machine learning is showing promising results in stress detection. Still, the viability of machine learning for digital biomarkers of stress is under-explored. In this work, we first investigate the performance of a supervised machine learning algorithm (Random Forest) with manual feature engineering for stress detection with contextual information. The concentration of salivary cortisol was used as the golden standard here. Our framework categorizes stress into No Stress, Low Stress, and High Stress by analyzing digital biomarkers gathered from wearable sensors. We also provide a thorough knowledge of stress in older adults by combining physiological data obtained from wearable sensors with contextual clues from a stress protocol. Our context-aware machine learning model, using sensor fusion, achieved a macroaverage F-1 score of 0.937 and an accuracy of 92.48% in identifying three stress levels. We further extend our work to get rid of the burden of manual feature engineering. We explore Convolutional Neural Network (CNN)-based feature encoder and cortisol biomarkers to detect stress using contextual information. We provide an in-depth look at the CNN-based feature encoder, which effectively separates useful features from physiological inputs. Both of our proposed frameworks, i.e., Random Forest with engineered features and a Fully Connected Network with CNN-based features validate that the integration of digital biomarkers of stress can provide more insight into the stress response even without any self-reporting or caregiver labels. Our method with sensor fusion shows an accuracy and F-1 score of 83.7797% and 0.7552, respectively, without context and 96.7525% accuracy and 0.9745 F-1 score with context, which also constitutes a 4% increase in accuracy and a 0.4 increase in F-1 score from RF.

Diurnal and day-to-day biological variation of salivary cortisol and cortisone.

There is a growing interest in the relevance of salivary cortisol and cortisone concentrations in stress-related research. To correctly attribute the magnitude of salivary cortisol and cortisone variation as an effect of a stressful event, a coherent understanding of the day-to-day intra-individual and inter-individual variability across the diurnal cycle of the two steroids is required. However, such information is currently lacking. This study aimed to overcome these existing limitations by performing an investigation of the biological variation (BV) of salivary cortisol and cortisone within one day and between five days using an LC-MS/MS method. Saliva samples were collected from 20 healthy volunteers immediately after waking up, at 8:00, 12:00, 15:00, 19:00 and 23:00 on each day over five days. All samples were analyzed in duplicate in one run. Nested ANOVA was used to calculate the sums of squares for analytical and biological components of variation. The within-subject BV of salivary cortisol and cortisone (CVI) ranged from a minimum of 29.3 and 19.0 % to a maximum of 56.5 and 49.1 %, respectively, while the between-subject biological variation (CVG) ranged from 29.7 and 29.0 % to 51.6 and 43.6 %. The reference change values (RCVs) ranged from 96 to 245 % for cortisol and from 55 to 194 % for cortisone. A medium index of individuality was observed for both compounds at all time points. This study provides updated BV estimates and RCVs for different times of day that can be used to assess the magnitude of change in biomarkers in future stress-related research.

102 Circadian patterns of behavior, respiration, rectal temperature, saliva melatonin, cytokine concentrations, and milk immune cells are altered by cooling heat-stressed lactating sows

Abstract Lactating sows are particularly vulnerable to heat stress (HS) due to the increased metabolism from milk production. A greater understanding of HS response could assist in mitigating its detrimental effects on animal production. Two core circadian clock genes were pinpointed in a recent genome study as potential mediators of HS response, indicating the possible alteration of circadian clocks by HS exposure. This study aimed to assess how cooling of lactating sows under natural heat stress conditions in the summer influenced circadian patterns of respiration rate (RR), rectal temperature (RT), behaviors, salivary concentration of cortisol and melatonin, milk cell populations and relative abundance of multiple cytokines in saliva. Lactating sows of mixed parities were divided into two treatment groups: treated with electronic cooling pad (C; n=9) and heat-stressed control (H; n=9). Experiments were conducted during two 48 h periods of increased environmental temperatures from summer heatwaves. During the initial 48 h period, rectal temperature (RT) was monitored every 60 min, rectal temperature (RT) every 30 min, and behaviors of eating, standing, sitting, laying, sleeping, drinking, and nursing every 5 min. Morning milk samples were collected following the completion of the first phase and utilized to categorize and count somatic cells. The second trial was approximately 1 wk later, and during this period saliva samples were collected every 4 h over the 48-h period. Results were analyzed for significant effect of treatments and interaction using periodic regression while circadian patterns were further detected by incorporating a Fourier series model utilizing sine-cosine variables that denote a fit and/or shift in circadian pattern. The analysis revealed that cooling decreased RT and RR while also modifying circadian patterns (P < 0.05). Cooling had no impact on the percentage of time spent in any activity over the 48-h period (P > 0.05). Nevertheless, the daily patterns of eating, standing, and sitting were different between the treatments (P < 0.05). A shift in eating time to later in the day in H sows relative to C sows related to a second rise in RT during the dark phase of the light-dark cycle (P < 0.05). Saliva melatonin concentrations were increased in C sows and circadian pattern altered relative to H (P < 0.05), but there was no effect on salivary cortisol concentrations (P > 0.05). Cooling reduced milk lymphocytes (P < 0.05) and influenced diurnal pattern of saliva cytokines including interleukins (IL) IL-1 alpha, IL-1 beta, IL-10, and IL-15 and transforming growth factor-beta 1. In conclusion, the cooling of heat-stressed sows altered the circadian patterns of physiology, behavior and melatonin, suggesting the need for additional research to investigate whether circadian disruption contributes to reduced production efficiency observed in HS animals.

Relationships among cortisol, perceived stress, and dental caries experience in adolescents and young adults.

Stress can impact mental and physical health, especially during adolescence and young adulthood. Previous studies have shown that salivary cortisol levels are elevated in both severe dental caries and periodontal disease. The role of stress in periodontal disease has been studied, but the extent of its contribution to dental caries is less well understood, especially in this age group. The present study aimed to assess the association between perceived stress, cortisol levels (in hair and saliva) and overall caries experience of adolescents and young adults aged between 15 and 25 years. Hair and saliva samples were obtained from 93 participants (age range=15-25 years) free of periodontal disease. Cortisol concentrations in hair and saliva were determined using a competitive enzyme-linked immunosorbent assay. Participants completed a perceived stress questionnaire and underwent full-mouth oral examination by a calibrated examiner. Dental caries experience was based on the decayed, missing, and filled teeth (DMFT) index. In addition, sociodemographic variables were recorded. Univariate and multivariable binary logistic regressions were used to assess the relationships of interest. There were significantly higher hair cortisol levels (p=0.042) and perceived stress scale (PSS) scores (p=0.026) in individuals with dental caries experience (DMFT≥1) than in those without (DMFT=0). However, there was no significant difference in salivary cortisol concentration (p=0.302). A binary logistic regression revealed that higher hair cortisol levels and greater scores on the perceived stress scale were associated with an increased odds of having experienced dental caries (OR=4.08, 95% CI 1.04, 15.96; OR=1.65, 95% CI 1.04, 2.63; respectively). In contrast, no significant association was found between dental caries and salivary cortisol concentration (OR=0.31, 95% CI 0.02, 4.23). Using multivariable regression models, caries experience was found to be significantly associated with both hair cortisol levels and PSS scores. These associations remained statistically significant even after adjusting for confounding sociodemographic variables. In the absence of periodontal disease, hair cortisol levels have a significant association with dental caries experience, whereas salivary cortisol concentrations do not. Hair cortisol levels may reflect the chronic physiological burden imposed by exposure to detrimental stressors.

Effects of different exercise intensities or durations on salivary IgA secretion.

This study aimed to examine changes in salivary immunoglobulin A (s-IgA) secretion at different intensities or durations of acute exercise. Twelve healthy untrained young males were included in randomized crossover trials in Experiment 1 (cycling exercise for 30min at a work rate equivalent to 35%, 55%, and 75% maximal oxygen uptake [ O2max]) and Experiment 2 (cycling exercise at 55% O2max intensity for 30, 60, and 90min). Saliva samples were collected at baseline, immediately after, and 60min after each exercise. Experiment 1: The percentage change in the s-IgA secretion rate in the 75% O2max trial was significantly lower than that in the 55% O2max trial immediately after exercise (-45.7%). The percentage change in the salivary concentration of cortisol, an s-IgA regulating factor, immediately after exercise significantly increased compared to that at baseline in the 75% O2max trial (+ 107.6%). A significant negative correlation was observed between the percentage changes in saliva flow rate and salivary cortisol concentration (r = -0.52, P < 0.01). Experiment 2: The percentage change in the s-IgA secretion rate in the 90-min trial was significantly lower than that in the 30-min trial immediately after exercise (-37.0%). However, the percentage change in salivary cortisol concentration remained the same. Our findings suggest that a reduction in s-IgA secretion is induced by exercise intensity of greater than or equal to 75% O2max for 30min or exercise duration of greater than or equal to 90min at 55% O2max in healthy untrained young men.

Relationship between Ear Temperature, Behaviour and Stress Hormones in Guinea Pigs (Cavia porcellus) during Different Interactive Activities in Zoos.

Guinea pigs (Cavia porcellus) are used for interactive activities in zoos; therefore, it is important to investigate their welfare. This study aimed to evaluate the validity of measuring the guinea pigs' body temperature of guinea pigs through the ear canal and investigate the relationship among changes in the expression of negative behavior, changes in body temperature, and changes in salivary cortisol concentration, and examine the effects of different interactive activities. In the normal interactive activities performed at the site, the decreased body temperature of pigs was observed over time. In contrast, increased body temperature was observed in excessive interactive activities, which are not recommended. Among the negative behaviors, "Head turning" and "Locomotion" increased significantly in excessive interactions compared to normal interactions, but "Head tossing" decreased significantly over time in both types of interactions. "Freezing" was observed only in excessive interactions. Salivary cortisol concentration increased significantly for all activities. Investigating the relationship between the individual expression of negative behavior and changes in body temperature and changes cortisol level made it possible to uncover the potential for inferring an animal's physiological state. Combining ear temperature monitoring and behavioral observation during zoo interaction activities is recommended as an ethical and scientifically supported practice.

Colorimetric Determination of Salivary Cortisol Levels in Artificial Saliva for the Development of a Portable Colorimetric Sensor (Salitrack)

Mental illnesses, such as clinical depression, have taken an unprecedented toll on society and the economy on a global scale. The relationship between stress management and mental health decline is of utmost significance, especially as most avenues of mental health management remain inaccessible for the majority of the general public, i.e., interview-based, and face-to-face interventions or costly drug-based therapies. Cortisol, the primary stress hormone, regulates the stress response in the human body and, through persistent activation, can lead to chronic stress and mental health deterioration. Thereby, the measurement and evaluation of cortisol within saliva could harness potential developments in management and diagnostic tools to monitor physiological and psychological stress in simple point-of-care applications. The current study aims to determine the concentration of salivary cortisol in spiked artificial saliva samples using blue tetrazolium (BT) dye as a colorimetric indicator. The proposed method showcases the use of the BT dye as an effective method for the rapid measurement of salivary cortisol, with accuracy comparable to the gold-standard method for salivary cortisol analysis, enzyme-linked immunoassays (ELISAs). Finally, a prototype colorimetric sensor has been developed for point-of-care applications of stress monitoring via salivary cortisol measurement.

Glucocorticoid response to naturalistic interactions between children and dogs

Although research has shown that pets appear to provide certain types of social support to children, little is known about the physiological bases of these effects, especially in naturalistic contexts. In this study, we investigated the effect of free-form interactions between children (ages 8–10 years) and dogs on salivary cortisol concentrations in both species. We further investigated the role of the child-dog relationship by comparing interactions with the child's pet dog to interactions with an unfamiliar dog or a nonsocial control condition, and modeled associations between survey measures of the human-animal bond and children's physiological responses. In both children and dogs, salivary cortisol decreased from pre- to post-interaction; the effect was strongest for children interacting with an unfamiliar dog (compared to their pet dog) and for the pet dogs (compared to the unfamiliar dog). We found minimal evidence for associations between cortisol output and behaviors coded from video, but children scoring higher on survey measures of the human-animal bond exhibited the greatest reductions in cortisol when interacting with dogs. Self-reported loneliness was not related to cortisol or the human-animal bond, but measures of both loneliness and the human-animal bond were higher among children who participated after the onset of the COVID-19 pandemic, relative to those who participated before the pandemic. This study builds on previous work that investigated potential stress-buffering effects of human-animal interaction during explicit stressors and demonstrates important physiological correlates of naturalistic interactions between children and dogs, similar to those that occur in daily life.

Exploring the effect of different typical plant community on human stress reduction: a field experiment

Research has demonstrated the positive effect of natural environment on human restoration and well-being. Time spent in nature can often alleviate both physiological and psychological stress. However, few studies have discussed the environmental health effects of the nature’s components and characteristics. Sixty volunteers were recruited and one manufactured environment and five different natural environments were randomly assigned to them, including coniferous forests (pure coniferous forest-PC and mixed coniferous forest-MC), broad-leaved forests (pure broad-leaved forest-PB and mixed broad-leaved forest-MB), and mixed forest (mixed coniferous and broad-leaved forest-MCB). Each volunteer sat in a built or natural environment and looked around the environment for 15 min. Physiological (HR, HRV, BP, pulse rate and salivary cortisol) and psychological indicators (POMS and STAI) were used to evaluate the changes in their stress level. Results indicated a strong difference in HR, HRV, POMS and STAI between the built and natural environment, which showed that natural environment can lower the stress level. MC had the best effect on relieving physiological stress, whereas MCB is most successful in improving emotional state and reducing anxiety. Broad-leaved forest and mixed forest significantly affected the DBP and vigor level of the subjects, respectively. While coniferous forest did significantly increase the concentration of salivary cortisol in subjects. The study confirmed that compared to the built environment, the natural environment can relieve the human body's physical and psychological stress and negative emotions, while significantly increasing vitality. And different plant communities also have different effects on the physiological and psychological indicators of the subjects. These results will provide scientific basis for the construction and improvement of urban green space environment.

Effect of Makeup Use on Depressive Symptoms: An Open, Randomized and Controlled Trial.

Depression is one of the most disabling diseases globally, with a high disease burden that generates high direct and indirect costs. The incidence of depression is twofold higher in adult women than in men. Biological and psychosocial factors constitute the pathophysiological bases of the condition and due to the complexity of the condition, current understanding is that the "treatment strategy must be multimodal". The objective of this study was to measure the effect of introducing the frequent use of makeup on improving depressive symptoms in adult women of medium-low purchasing power METHODS: Participants with the targeted profile who did not frequently use makeup were selected and randomised to receive (test group) or not (control group) stimuli and makeup products intended for encouraging the frequent use of makeup. The Zung Depression Self-Assessment Scale was used to assess depressive symptoms, with additional assessments on self-image perception using the mirror test and salivary cortisol level. The results demonstrated a sustained reduction in depressive symptoms (8.3 percentage points reduction in the Average Zung Index; P < 0.05), with a significant improvement in self-image perception (25% increase in the average score obtained in the mirror test; P < 0.05) and a specific influence on salivary cortisol levels (55% reduction in salivary cortisol concentration; P < 0.05) after the first makeup application. The results show that encouraging the frequent use of makeup, a practice that can be achieved by most people and which is simple and inexpensive to implement, can contribute to effective and sustainable improvement in the well-being and mental health of a significant portion of the population.

In and out Beauty and Sensitive Skin, a Psychophysiological Exploration: Myth or Reality?

Knowing that biomolecules, such as β-amyrin and α-amyrin, have some pharmacological effects, the aim of this study was directed towards exploring the protective effect of Tomato Peel and Seed Extract (TPSE) for its soothing function but also for its capacity to modulate the adrenal axis, which is involved in stress response. Ex vivo tests were carried out on skin explants to evaluate the effectiveness of TPSE formulated at 0.5% on Calcitonin Gene-Related Peptide (CGRP) and IL-10 release, Kappa Opioid Receptor (KOR), and Caspase 14 expression. An in vivo study combined a clinical evaluation of skin homogeneity and psychological parameters as well as an analysis of salivary cortisol and dehydroepiandrosterone concentrations. All measurements were carried out at the beginning and after 28 days of applying a TPSE face cream. TPSE regulated not only the release of CGRP, IL-10, and the expression of Caspase 14, reflecting anti-neurogenic and anti-inflammatory properties, but also modulated KORs. Twenty-eight days of TPSE application induced a significant decrease in intensity and extent erythrosis, a lower output of salivary cortisol, and a significant increase in pleasant emotions when compared to placebo. These results provide encouragement to continue exploring the impact of cosmetic ingredients on psychophysiological parameters to improve skin health and well-being.

Effects of cannabidiol on psychosocial stress, situational anxiety and nausea in a virtual reality environment: a protocol for a single-centre randomised clinical trial

IntroductionThe non-intoxicating plant-derived cannabinoid, cannabidiol (CBD), has demonstrated therapeutic potential in a number of clinical conditions. Most successful clinical trials have used relatively high (≥300 mg) oral doses of CBD....

Clinical significance of endocrine disorders in the development of early vascular aging in males with abdominal obesity and concomitant arterial hypertension: An observational cohort study

Background. Visceral obesity is a risk factor in the development of metabolic and endocrine disorders leading to arterial hypertension and cardiovascular complications. Their early predictors include increased vascular stiffness and early vascular aging. The current literature lacks studies into the effects of changes in testosterone, cortisol, and aldosterone levels in serum on vascular stiffness and the development of early vascular aging in patients with visceral obesity. Objective. To determine the relationship between hypercortisolemia, hyperaldosteronemia, and hypotestosteronemia and vascular stiffness and the presence of early vascular aging in male patients with visceral obesity. Methods. An observational cohort study of 78 males aged 35–45 years (mean age 38.1 ± 6.5 years) diagnosed with abdominal obesity and grade 1 arterial hypertension was conducted. The mean waist circumference ranged 105.5 ± 6.9 cm; systolic and diastolic blood pressure ranged 152.5 ± 5.0 and 92.5 ± 5.0 mm Hg, respectively. The vascular age of the studied patients (n = 78) comprised 44.1 ± 6.2 years, which was statistically higher than their passport age (р &lt; 0.001). The studied patients were divided into subgroups according to both total testosterone (&lt; 12.1 nmol/l in subgroup 1A (n = 49) and ≥ 12.1 nmol/L in subgroup 1B (n = 29)) and cortisol in the evening saliva portion (&gt; 4.5 nmol/L in subgroup 2A (n = 24) and ≤ 4.5 nmol/L in subgroup 2B (n = 24)). All the patients completed the study. To assess the hormonal status, the total testosterone sex steroid-binding globulin (SSBP) and insulin in morning serum samples were investigated. Insulin resistance was assessed based on the NOMA-IR index. The concentration of total testosterone was determined by enhanced chemiluminescence (Ortho-Clinical Diagnostics, J&amp;J); the SSBP and insulin levels were determined by delayed fluorescence. Aldosterone content was determined by radioimmunoassay; free cortisol and testosterone were measured by luminescent LIA. Free and bioavailable testosterone concentrations in serum were calculated using an online calculator (issam.ch/freetesto.htm). The cardio-ankle vascular index (CAVI) was determined using a VaSera VS-15000N device, which automatically calculated the vascular age. Statistical analysis was performed using the Statistica 10.0 Windows package (StatSoft, Inc., USA). Results. The vascular age of patients with hypogonadism was statistically significantly ( р &lt; 0.001) higher than their passport age and the vascular age in males without hypogonadism. The CAVI and vascular age were also statistically significantly higher in males with functional hypercorticism (р &lt; 0.001) compared with a subgroup of patients without hypercorticism. The vascular age and CAVI increased with an increase in the salivary cortisol concentration 2200 (r = 0.5; р &lt; 0.05) and decreased with an increase in the salivary cortisol level 900 (r = –0.5; р &lt; 0.05). These parameters decreased with an increase in serum aldosterone obtained in the morning (r = –0.4; p &lt; 0.05) and increased with an increase in serum aldosterone in the evening (r = 0.4; p &lt; 0.05). In 23% (n = 18), an inversion of the daily rhythm of cortisol production was observed; in these patients, salivary cortisol levels of 2200 exceeded salivary cortisol levels of 900. The vascular age of patients with the inversion of cortisol production (49.4 ± 4.4 years) was statistically significantly ( р &lt; 0.001) different from that of patients with normal changes in salivary cortisol concentrations (41.9 ± 4.9 years). CAVI was also higher (р &lt; 0.001) in males with inverted fluctuations in salivary cortisol levels (7.51 ± 0.62) compared to those with normal diurnal rhythm (6.45 ± 0.69). The results of aldosterone evaluation revealed that 17% of the patients (n = 13) had higher aldosterone levels in the evening serum portion compared to the morning serum portion. In these patients, the vascular age (45.8 ± 5.1 years) was higher ( р &lt; 0.001) than that in males with normal physiologic changes in aldosterone levels (41.6 ± 5.7 years). A similar pattern was observed when comparing vascular stiffness indices. Thus, the CAVI in men with inverted changes in aldosterone concentration (6.9 ± 0.8) was significantly higher ( р &lt; 0.001), compared to that in men with physiological changes in blood aldosterone levels (6.4 ± 0.8). Conclusion. Endocrinologic disorders in male patients with visceral obesity and concomitant arterial hypertension (functional hypogonadism, functional hypercorticism, inverted daily rhythms of cortisol and aldosterone production) contribute to the development of early vascular aging by increasing vascular stiffness.

Salivary testosterone and cortisol response in acute stress modulated by seven sessions of mindfulness meditation in young males

Stress is an established risk factor for negative health outcomes. Salivary cortisol and testosterone concentrations increase in response to acute psychosocial stress. It’s crucial to reduce stress for health and well-being through evidence-based interventions. Body-mind interventions such as meditation and Tai Chi have shown reduced cortisol levels but mixed results in testosterone concentration after stress. To address this research gap, we conducted a pilot randomized controlled trial to examine the modulating effects of a short-term (seven 20-minute sessions) mindfulness meditation on testosterone and cortisol in response to acute stress. Using one form of mindfulness meditation – Integrative Body-Mind Training (IBMT) and an active control–relaxation training (RT), we assessed salivary cortisol and testosterone concentrations at three stages of stress intervention – rest, stress, and an additional 20-min IBMT or RT practice. We found increased cortisol and testosterone concentrations after acute stress in both groups, but testosterone rise was not associated with cortisol rise. Moreover, an additional practice immediately after stress produced higher testosterone concentrations in the IBMT group than the RT group, whereas cortisol concentration increased in the RT group than in the IBMT group at the same time point. These findings indicate that brief mindfulness intervention modulates a dual-hormone profile of testosterone and cortisol in response to acute stress presumably via the co-regulation of hypothalamus-pituitary-adrenal and hypothalamus-pituitary-testicular axes.

Sleep Quality and Evening Salivary Cortisol Levels in Association with the Psychological Resources of Parents of Children with Developmental Disorders and Type 1 Diabetes.

Sleep deprivation can decrease parental well-being and degrade mental and physical health in parents of children with chronic illness. The aim of this study was to explore the associations of sleep quality, psychological stress perception, and evening salivary cortisol concentration with self-esteem, optimism and happiness in parents of children with type 1 diabetes and developmental disorders compared to parents of healthy, typically developing children. We studied 196 parents of children with chronic conditions, including autistic spectrum disorder (N = 33), cerebral palsy (N = 18), Down syndrome (N = 33), and diabetes mellitus type 1 (N = 40) and parents of healthy children (N = 72). We evaluated parental sleep quality, evening salivary cortisol levels, self-esteem, optimism and happiness. Multiple linear regression models were used to assess associations between variables. Compared with those of the control group, the parents of children with autistic spectrum disorders had higher evening cortisol concentrations (β = 0.17; p = 0.038) and lower perceptions of happiness (β=-0.17; p = 0.017), while parents of children with type 1 diabetes had disrupted sleep quality (β = 0.25; p = 0.003). Optimism was negatively associated with the evening cortisol concentration (β=-0.18; p = 0.023) and sleep quality index (β=-0.20; p = 0.012). Public health programs aimed at lifestyle habit improvement, respite care, and relaxation for parents of children with chronic conditions would be useful for improving parental sleep quality, self-esteem, optimism and happiness.

Effect of acute stress on working memory in pilots: Investigating the modulatory role of memory load.

Many practitioners, such as pilots, frequently face working memory (WM) demands under acute stress environments, while the effect of acute stress on WM has not been conclusively studied because it is moderated by a variety of factors. The current study investigated how acute stress affects pilots' WM under different memory load conditions. There are 42 pilots conducting the experiments, consisting of 21 stress group participants experiencing the Trier Social Stress Test (TSST) and 21 control group participants experiencing the controlled TSST (C-TSST). Subsequently, both groups performed N-back tasks under three memory load conditions (0-back, 1-back, and 2-back). State Anxiety Inventory (S-AI), heart rate (HR), and salivary cortisol concentrations (SCC) were collected to analyze acute stress induction. The results revealed that (1) the TSST could effectively induce acute stress with higher S-AI, HR, and SCC; (2) higher memory load reduces WM accuracy (ACC) and delays response times (RT); (3) acute stress increases WM ACC under moderate load conditions (1-back task). These results suggest that acute stress may not necessarily impair WM and even improve WM performance under certain memory load conditions. Potential mechanisms of acute stress effects on WM and alternative explanations for the modulatory role of memory load consistent with the emotion and motivation regulation theory are discussed. These findings not only provide insight into the field of acute stress and WM but are also beneficial for pilot training and the development of stress management strategies.

Ultrasensitive electrochemical sensor for detection of salivary cortisol in stress conditions.

A natural stress response induces elevated cortisol levels in biological fluids, such as saliva. While current sensor technologies can detect cortisol in real time, their sensitivity and reliability for human subjects have not been assured. This is due to relatively low concentrations of salivary cortisol, which fluctuate throughout the day and vary significantly between individuals. To address these challenges, we present an improved electrochemical biosensor leveraging graphene's exceptional conductivity and physicochemical properties. A1-pyrenebutyric acid N-hydroxysuccinimide ester (PBASE-NHS)-modified commercial graphene foam (GF) electrode is presentedto realize an ultra-sensitive biosensor for cortisol detection directly in human saliva. The biosensor fabrication process entails the attachment of anti-cortisol monoclonal antibodies (mAb-cort) onto a PBASE-NHS/GF electrode through noncovalent immobilization on the vertically stratified graphene foam electrode surface. This unique immobilization strategy preserves graphene's structural integrity and electrical conductivity while facilitating antibody immobilization. The binding of cortisol to immobilized mAb-cort is read out via differential pulse voltammetry using ferri/ferro redox reactions. The immunosensor demonstrates an exceptional dynamic range of 1.0fgmL-1 to 10,000pgmL-1 (R2 = 0.9914) with a detection limit of 0.24fgmL-1 (n = 3) for cortisol. Furthermore, we have established the reliability of cortisol sensors in monitoring human saliva. We have also performed multiple modes of validation, one against the established enzyme-linked immunosorbent assay (ELISA) and a second by a third-party service Salimetric on 16 student volunteers exposed to different stress levels, showing excellent correlation (r = 0.9961). These findings suggest the potential for using mAb-cort/PBASE-NHS/GF-based cortisol electrodes for monitoring salivary cortisol in the general population.

Association between Eosinophil Count and Cortisol Concentrations in Equids Admitted in the Emergency Unit with Abdominal Pain.

Stress leukogram includes eosinopenia as one of its main markers (neutrophilia, eosinopenia, lymphopenia, and mild monocytosis). Cortisol is the main stress biomarker, which is also strongly correlated with the severity of gastrointestinal diseases. This study aimed to determine the relationship between salivary cortisol and the eosinophil cell count (EC) in equids with abdominal pain. To do this, 39 horses with abdominal pain referred to an emergency service were included. All samples were taken on admission, and several parameters and clinical data were included. Equids were classified according to the outcome as survivors and non-survivors. Non-surviving equids presented higher salivary cortisol concentrations (Non-Survivors: 1.580 ± 0.816 µg/dL; Survivors 0.988 ± 0.653 µg/dL; p < 0.05) and lower EC (Non-Survivors: 0.0000 × 103/µL (0.000/0.0075); Survivors: 0.0450 × 103/µL (0.010/0.1825); p < 0.01). In addition, the relationship between salivary cortisol concentration, EC, and the WBC was determined. Only a strong correlation (negative) was observed between cortisol and EC (r = -0.523, p < 0.01). Since cortisol is not an analyte that can be measured routinely in clinical settings such as emergencies, the EC could be a good alternative. While the results are promising, further studies are needed before EC can be used confidently in routine practice to predict survival in cases of abdominal pain.

Effect of the “K” technique on levels of anxiety and salivar cortisol in adolescents

This research presents theoretical arguments of a new approach called Technique “K,” which aims to reduce student’s anxiety before a cognitive challenge. Through a randomized, controlled clinical trial, we evaluate the Beck Anxiety Inventory and salivary cortisol. We compared the results in the last year of high school, who were facing school tests, before and after the application of the “K” technique (intervention group) and placebo (control group). Statistical analyses consisted of using the Chi-square, Spearman and the Wilcoxon test. The principal component analysis observed in the case group, - 10.50 (-18.25; -4.75), was statistically higher than the control group, -6.00 (-8.75; -1.25). It is not possible to identify statistical significance (p = 0.462) in the variation of salivary cortisol concentration. The results suggest the effectiveness of the “K” technique in managing anxiety in high school students. Although, future research is needed to extend the preliminary data obtained in this study.

Low Urinary Free Cortisol as a Risk Factor for Patients with Variceal Bleeding.

Background and Objectives: Specificity and reliability issues of the current cortisol assessment methods lead to limitations on the accurate assessment of relative adrenal insufficiency. Although free cortisol provides a more accurate evaluation of adrenal cortisol production, the expense and time-consuming nature of these assays make them impractical for routine use. Research has, thus, focused on alternative methods, such as indirectly measuring free cortisol using Coolens' equation or directly assessing salivary cortisol concentration, which is considered a more favorable approach despite associated challenges like sampling issues and infection risks. The aim of this study was to explore correlations between 24 h urinary free cortisol (UFC), free plasma cortisol, serum total cortisol, and salivary cortisol as potential reliable indices of free cortisol in the setting of variceal bleeding. Additionally, we assessed the predictive value of UFC for 6-week mortality and 5-day treatment failure in patients with liver cirrhosis and variceal bleeding. Materials and Methods: A total of 40 outpatients with liver cirrhosis and variceal bleeding were enrolled. Free cortisol levels in serum, saliva, and urine were assessed using the electrochemiluminescence immunoassay method. For the measurement of plasma-free cortisol, a single quadrupole mass spectrometer was employed. The quantification of free cortisol was fulfilled by analyzing the signal response in the negative ESI-MS mode. Results: UFC was significantly correlated to free plasma cortisol. Negative correlations were demonstrated between UFC, the Child-Pugh (CP) score, and C reactive protein (CRP) levels. In the multivariate analysis, CP stage C was associated with 6-week mortality risk and portal vein thrombosis with 5-day treatment failure using Cox regression and binary logistic regression analyses, respectively. Patients who experienced rebleeding, infection, or death (or any combination of these events) presented with lower levels of UFC. Conclusions: This study suggests that low levels of UFC may impose a risk factor for patients with liver cirrhosis and variceal bleeding. The use of UFC as an index of adrenal cortisol production in variceal bleeding warrants further investigation.