Background: The COVID-19 virus outbreak had a massive effect on many parts of people's lives, as they were advised to quarantine and lockdown to prevent the virus from spreading, which had a big impact on people's mental health, anxiety, and stress. Many internal and external factors lead to stress. This negatively influences the body's homeostasis. As a result, stress may affect the body's capacity to use energy to defend against pathogens. Many recent investigations have found substantial links between human mental stress and the production of hormones, prohormones, and/or immunological chemicals. some of these researches have verified the link between stress and salivary cortisol levels. The aim of this study is to measure salivary cortisol as a stress biomarker as well as a total viable count of salivary bacterial microbiome among COVID-19 patients. Materials and methods: a sample of 84 adults patients was collected who were divided into two groups: the COVID-19 group consists of 42 patients and the COVID-19 free group which consists of 42 subjects. All subjects undergo a PCR test to confirm their health status. The collection of Un-stimulated saliva was done. Laboratory investigations were carried out to measure the total viable count of the salivary bacterial microbiome by culturing on Brain Heart Infusion Agar and to evaluate the salivary cortisol level using cortisol kit (Elecsys Cortisol II). Results: SPSS version 21 was used for statistical analysis. According to the statistical analysis, the salivary cortisol and total viable count of salivary bacterial microbiome values were substantially greater in the COVID-19 group than in the COVID-19 free group. Conclusion: A positive association was found between salivary cortisol and the total viable count of the salivary bacterial microbiome. So, when the concentration of salivary cortisol is elevated in the COVID-19 group, the level of the total viable count of the salivary bacterial microbiome is also elevated.

The ability to quickly and accurately determine cortisol as a biomarker for stress is a valuable tool in assessing the wellbeing of NHP. In this study, 2 methods of collecting saliva (a commercial collection device and passive drool) and the resulting free salivary cortisol levels were compared with total serum cortisol concentration in rhesus macaques (Macaca mulatta), cynomolgus macaques (Macaca fascicularis) and African green monkeys (Chlorocebus aethiops) at 2 collection time points. Serum and salivary cortisol levels were determined using a competitive quantitative ELISA. In addition, both saliva collection methods were evaluated for volume collected and ease of use. Compared with passive drool, the experimental collection device was more reliable in collecting sufficient volumes of saliva, and the resulting salivary cortisol values demonstrated stronger correlation with serum cortisol concentration in all species and collection days except cynomolgus macaques on day 1. This saliva collection device allows quick and reliable sample collection for the determination of salivary cortisol levels. In addition, the results might provide a useful tool for evaluating hypothalamic-pituitary-adrenal axis activity or the physiologic stress reaction in NHP as well as a biomarker of psychologic stress states in a variety of situations.

Fibromyalgia (FM) is a complex chronic syndrome marked by widespread musculoskeletal pain, neurocognitive dysfunction ("fibro-fog"), and autonomic disturbances. Clinical management remains challenging due to subjective symptom reporting and the lack of definitive diagnostics. Emerging evidence points to a multifactorial origin involving central sensitization, neuroendocrine imbalance, and systemic immune-inflammatory alterations. A wide array of candidate biomarkers has been reported in FM, encompassing neurotransmitters (serotonin, norepinephrine), excitatory and inhibitory amino acids, metabolic and glycolytic enzymes, stress-related proteins, autoantibodies, oxidative stress markers and pro-inflammatory cytokines. This molecular heterogeneity reflects the systemic and multidimensional nature of FM. However, most of these biomarkers have been primarily investigated in serum or plasma, where analytical validation and reference ranges are more established. In contrast, the exploration of salivary biomarkers-although highly attractive due to its non-invasive, stress-free, and repeatable collection-remains comparatively limited. Saliva contains a reduced concentration range of many systemic markers and is strongly influenced by circadian rhythms, stress, flow rate, and oral health conditions. While promising candidates such as α-amylase, cortisol, calgranulins, and selected metabolic enzymes have shown potential in saliva, many proposed FM-related biomarkers lack full analytical validation, standardized protocols, and clinically defined reference intervals in this matrix. In this context, non-invasive electrochemical biosensors represent a transformative technological approach. Advanced electrode architectures incorporating nucleic acid probes, redox reporters, and nanostructured materials offer high sensitivity in low-volume and low-concentration biofluids such as saliva. The integration of multiplexed biomarker panels into portable platforms could enable real-time, longitudinal monitoring of FM pathophysiology, supporting phenotype stratification, personalized therapeutic adjustment, and objective disease activity tracking.

Several large‐scale epidemiological studies have demonstrated the prognostic significance of psychosocial factors and stress for coronary artery disease (CAD). Observations of sudden changes in CAD incidence have led to the proposal of mechanisms regarding atherosclerotic plaque vulnerability. The collagen‐degrading enzyme matrix metalloproteinase-9 (MMP-9) is increased in rupture‐prone plaques with high inflammatory activity, and circulating levels of MMP-9 are raised in patients with acute coronary syndrome. However, the distribution of MMP‐9 levels and its relations to psychosocial factors and the stress hormone cortisol have not been previously explored in a normal population.The aim of this dissertation was to examine in a normal population the association of circulating levels of MMP-9 with traditional cardiovascular risk factors including levels of C-reactive protein (CRP), with psychosocial factors, and with saliva levels of cortisol. In addition, the reliability of a new method of ambulatory saliva sampling for assessment of cortisol levels was evaluated. A sub‐sample of the Life conditions, Stress, and Health (LSH)-study, a population based study exploring psychoneuroendocrinological pathways mediating the differences in CAD incidence over socioeconomic status, was used. Plasma levels of MMP-9 were examined in a sample randomly drawn from the LSH‐study (n=400), aged 45 to 69 years at enrollment.The main findings were: 1) there was a positive association between plas

Cortisol is a key biomarker of stress and hypothalamic-pituitary-adrenal (HPA) axis activity in an organism. Different biological samples are used for measuring cortisol levels, such as blood, saliva, milk, urine, faeces, and hair. Blood plasma or serum cortisol measurements are widely applied to quantify acute stress response in farm animals, but stress sampling and rapid hormonal changes can undermine accuracy in results. Saliva has proven to be a reliable alternative sample for assessing free cortisol, offering a less stressful approach with minimal triggering of the stress response. Cortisol determination in milk is a non-invasive method of limited applicability for lactating ruminants, though physiological parameters such as milk yield and stage of lactation can influence its interpretation. Concentrations of cortisol in urine reflect the cumulative cortisol secretion over time, making it a valuable indicator of chronic stress, though research on small ruminants remains limited. Similarly, faecal cortisol metabolites offer a non-invasive means of assessing adrenal activity with delayed but integrated hormonal fluctuations. Hair and wool analysis provide insight into long-term stress exposure, though factors such as seasonal variation and local synthesis complicate its application. This review highlights the strengths and challenges associated with different cortisol sampling methods, emphasising the importance of multiple biological sample approaches for accurate welfare

This study provides a focused review on the use of saliva biomarkers, particularly salivary cortisol, for measuring cognitive fatigue. Through a systematic review and analysis of 25 articles sourced from five academic databases, we examine the relationship between cognitive fatigue and saliva biomarkers. The findings highlight the potential of salivary cortisol as an effective marker of cognitive fatigue, while also identifying limitations in current methodologies, including inconsistent saliva collection and analysis procedures. Although prior reviews have explored saliva biomarkers, our analysis focuses on gaps related to the empirical connection between cognitive fatigue and biomarkers. This review further meta-analysis reveals that cortisol and alpha-amylase levels significantly increased after completing cognitive fatigue-inducing tasks. Moreover, this review emphasizes the need for updated, standardized protocols and real-time detection methods. Future research should aim to conduct more focused empirical investigations to advance the field.

<h4>Background</h4>Stress is recognised as a contributing risk factor for temporomandibular disorders (TMDs), and salivary stress biomarker levels may be altered in such patients.<h4>Objectives</h4>This systematic review aimed to assess the current evidence to determine the association between salivary stress biomarkers and temporomandibular disorders (TMDs).<h4>Methods</h4>PubMed, Cochrane, Google Scholar and Scopus were searched. Case-control and cross-sectional studies exploring the association of salivary stress biomarkers in adult subjects with TMDs were included. A random effects model was used for quantitative data analysis. Risk-of-bias was assessed using the Newcastle-Ottawa Scale (NOS).<h4>Results</h4>Out of 5319 studies, 16 studies met the eligibility criteria. All included studies were case-control studies; they included 549 TMD cases and 494 controls. Overall, TMD cases showed higher levels of morning unstimulated salivary cortisol compared to controls (SMD: 1.38, 95% CI: 0.40-2.36), whereas the level of evening cortisol between both groups was non-significant (SMD: 0.47, 95% CI: -0.00 to 0.95). Also, the qualitative results showed that the salivary oxidative-stress biomarker was increased in the TMD group compared to controls.<h4>Conclusion</h4>The level of morning salivary cortisol seems to be increased in patients with TMDs compared to controls. This may indicate an association of salivary stress biomarkers and TMDs, although the level of evidence is very low. Therefore, further standardised studies are required to support these findings.

Each form of violence constitutes a significant social problem and presents a diagnostic challenge, particularly from the perspective of medico-legal assessment. Moreover, as a stressor, violence influences the levels of biomarkers that can be measured in saliva, an easily accessible material for testing. This systematic review aimed to assess changes in salivary hormonal biomarker levels among individuals experiencing various forms of violence, with particular emphasis on cortisol. Following the established inclusion and exclusion criteria, 22 studies were included. Most studies originated from Europe and the USA and encompassed both children and adults. Cases of interpersonal violence were analyzed, particularly physical, sexual, and psychological violence, including bullying. Based on the analysis of the included studies, trends in alterations of salivary cortisol levels and its diurnal secretion profile were identified. The conducted meta-analysis demonstrated slightly lower morning cortisol levels and significantly elevated evening cortisol levels in abused individuals. Further research is necessary to precisely characterize the impact of violence on salivary cortisol levels to evaluate the potential use of this parameter for the objective, real-time diagnosis of violent events. Such advancements would facilitate the implementation of victim care programs and enhance the detection of violence.