Measurement of cortisol in saliva: a comparison of measurement error within and between international academic-research laboratories

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

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Neural habituation during acute stress signals a blunted endocrine response and poor resilience

BACKGROUND

A blunted hypothalamic-pituitary-adrenal (HPA) axis response to acute stress is associated with psychiatric symptoms. Although the prefrontal cortex and limbic areas are important regulators of the HPA axis, whether the neural habituation of these regions during stress signals both blunted HPA axis responses and psychiatric symptoms remains unclear. In this study, neural habituation during acute stress and its associations with the stress cortisol response, resilience, and depression were evaluated.

METHODS

Seventy-seven participants (17-22 years old, 37 women) were recruited for a ScanSTRESS brain imaging study, and the activation changes between the first and last stress blocks were used as the neural habituation index. Meanwhile, participants' salivary cortisol during test was collected. Individual-level resilience and depression were measured using questionnaires. Correlation and moderation analyses were conducted to investigate the association between neural habituation and endocrine data and mental symptoms. Validated analyses were conducted using a Montreal Image Stress Test dataset in another independent sample (48 participants; 17-22 years old, 24 women).

RESULTS

Neural habituation of the prefrontal cortex and limbic area was negatively correlated with cortisol responses in both datasets. In the ScanSTRESS paradigm, neural habituation was both positively correlated with depression and negatively correlated with resilience. Moreover, resilience moderated the relationship between neural habituation in the ventromedial prefrontal cortex and cortisol response.

CONCLUSIONS

This study suggested that neural habituation of the prefrontal cortex and limbic area could reflect motivation dysregulation during repeated failures and negative feedback, which might further lead to maladaptive mental states.

Adverse Childhood Experiences: Associations with a Blunted Cortisol Stress Response During Pregnancy

INTRODUCTION

Adverse Childhood Experiences (ACEs) are associated with a range of negative physical and mental health outcomes, yet there is limited research focused on the effect of ACEs on stress responses during pregnancy. Expectant mothers experience an increase in cortisol levels as pregnancy progresses, with this increase having important implications for fetal and early infant development. Little is known about the impact of ACEs on maternal cortisol levels. This study explored the relationship between maternal ACEs and cortisol response among expectant mothers nearing or in the third trimester of pregnancy.

METHODS

39 expectant mothers were exposed to a Baby Cry Protocol via an infant simulator, with salivary cortisol collected at five points in time (N = 181). Stepwise, multilevel model creation resulted in a random intercept and random slope model with an interaction term for total number of ACEs and week of pregnancy.

RESULTS

The repeated measures data showed that cortisol levels decreased across collection times, from arrival at the lab, through the Baby Cry Protocol, to recovery. Predictive margins for the interaction term showed that while exposure to a greater number of ACEs was associated with higher cortisol levels early in the third trimester, the expected increase in cortisol late in pregnancy was blunted for expectant mothers who were exposed to a greater number of ACEs.

DISCUSSION

These findings findings suggest the importance of ACEs screening and intervention efforts as part of prenatal care.

Cortisol: Analytical and clinical determinants

Cortisol, the main human glucocorticoid, is synthesized from cholesterol in the adrenal cortex and predominantly metabolized by the liver. Interpretation of quantitative results from the analysis of serum, urine and saliva is complicated by variation in circadian rhythm, response to stress as well as the presence of protein-bound and free forms. Interestingly, cortisol is the only hormone routinely measured in serum, urine, and saliva. Preanalytical and analytical challenges arise in each matrix and are further compounded by the use of various stimulation and suppression tests commonly employed in clinical practice. Although not yet included in clinical guidelines, measurement of cortisol in hair may be of interest in specific situations. Immunoassays are the most widely used methods in clinical laboratories to measure cortisol, but they are susceptible to interference from synthetic and endogenous steroids, generally producing a variable overestimation of true cortisol results, especially in urine. Analysis by mass spectrometry provides higher specificity and allows simultaneous measurement of multiple steroids including synthetic steroids, thus reducing diagnostic uncertainty. An integrated review of cortisol in various disease states is also addressed.

The Impact of Therapy Dogs on Prelicensure Baccalaureate Nursing Student Test Anxiety

AIM

This study examined the impact of a therapy dog intervention on baccalaureate nursing student test anxiety.

BACKGROUND

Nursing student test anxiety may hinder academic performance and program outcomes. Considering this negative impact, it is essential to implement anxiety-reducing strategies. Interaction with therapy dogs is linked with test anxiety reduction; however, minimal studies have explored this topic.

METHOD

A pretest/posttest quasi-experimental design was used to examine the impact of a therapy dog intervention on test anxiety. Repeated measures included the State-Trait Anxiety Inventory, heart rate, and cortisol levels. The multisite convenience sample included 91 junior-level prelicensure BSN students.

RESULTS

The intervention had a statistically significant impact on test anxiety reduction, noted by a decrease in State-Trait Anxiety Inventory scores, heart rate, and salivary cortisol levels ( p = .00).

CONCLUSION

Therapy dog interactions are an effective strategy to reduce test anxiety. The findings from this study may assist educators to implement future interventions.

Promising applications of human-derived saliva biomarker testing in clinical diagnostics

Saliva testing is a vital method for clinical applications, for its noninvasive features, richness in substances, and the huge amount. Due to its direct anatomical connection with oral, digestive, and endocrine systems, clinical usage of saliva testing for these diseases is promising. Furthermore, for other diseases that seeming to have no correlations with saliva, such as neurodegenerative diseases and psychological diseases, researchers also reckon saliva informative. Tremendous papers are being produced in this field. Updated summaries of recent literature give newcomers a shortcut to have a grasp of this topic. Here, we focused on recent research about saliva biomarkers that are derived from humans, not from other organisms. The review mostly addresses the proceedings from 2016 to 2022, to shed light on the promising usage of saliva testing in clinical diagnostics. We recap the recent advances following the category of different types of biomarkers, such as intracellular DNA, RNA, proteins and intercellular exosomes, cell-free DNA, to give a comprehensive impression of saliva biomarker testing.

Psychosocial Stress and Hypothalamic-Pituitary-Adrenal Axis Stress Reactivity: Variations by Race and Socioeconomic Status Among Adults at Risk of Diabetes

OBJECTIVE

Although stress is posited to play a key role in health disparities, the extent to which commonly used self-report psychosocial stress measures are related to neurobiological stress processes, especially across diverse populations, is unresolved. This study examined how two measures of psychosocial stress, perceived stress and domain-specific stress, covary with the acute neurobiological stress response.

METHODS

The Richmond Stress and Sugar Study includes a racially and socioeconomically diverse cohort of adults at risk for type 2 diabetes ( n = 125; mean age = 57 years, 48% Black, and 61% high neighborhood socioeconomic status [SES]). Hypothalamic-pituitary-adrenal axis reactivity was assessed by salivary cortisol response to the Trier Social Stress Test (TSST), a laboratory stressor.

RESULTS

Higher perceived stress was associated with a lower cortisol response to the TSST (-7.5%; 95% confidence interval [CI] = -13.1% to -1.5%) but was not associated with cortisol recovery after the TSST (3%; 95% CI = -0.6% to 6.8%). In contrast, domain-specific stress was not associated with cortisol response (-2.1%; 95% CI = -20.7% to 20.9%) but was inversely associated with cortisol recovery (3.7%; 95% CI = 0.6% to 7.0%). SES modified these associations: both perceived stress and domain-specific stress were associated with TSST cortisol response only among participants from high-SES neighborhoods. There was minimal evidence of effect modification by race.

CONCLUSIONS

Both self-report measures of psychosocial stress were associated with hypothalamic-pituitary-adrenal axis reactivity to an acute stressor. These associations varied by perceived versus domain-specific measurement scales and by neighborhood SES. Further efforts to refine stress measures and clarify biological linkages between social status and health are needed.

Polysomnography-estimated sleep and the negative feedback loop of the hypothalamic-pituitary-adrenal (HPA) axis

BACKGROUND

Sleep and stress are highly interrelated. To improve our understanding of the role of sleep in functioning of the negative feedback loop of the stress system, we assessed the association between sleep and functioning of the hypothalamic-pituitary-adrenal (HPA) axis in a population-based sample.

METHODS

This study included 403 participants (mean age: 62.4 ± 5.0 years, 55% women) of the population-based Rotterdam Study. Between 2012 and 2014, sleep was assessed with polysomnography. Functioning of the negative feedback loop of the HPA axis was estimated by measuring cortisol levels before and after the intake of a very low dose of dexamethasone (0.25 mg) on average 0.9 ± 37.8 days after the polysomnography. We used linear regression analyses adjusted for multiple confounders and performed sensitivity analyses in a sample excluding those with clinically relevant depressive symptoms and using psychoactive medicine, and a sample excluding non-suppressors.

RESULTS

Short N2 sleep (adjusted difference = 0.005, 95%CI = 0.002;0.009), long N3 sleep (adjusted difference = -0.007, 95%CI = -0.010;-0.003), and short sleep onset latency (adjusted difference = 0.006, 95%CI = 0.001;0.011) were associated with an enhanced response to dexamethasone, but the association of sleep onset latency did not survive multiple testing correction. Associations remained similar after excluding those with clinically relevant depressive symptoms and those using psychoactive medicine or exclusion of non-suppressors.

CONCLUSIONS

This study suggests that more slow wave sleep is particularly associated with a stronger suppression of cortisol within the negative feedback loop of the HPA axis. These findings provide further support that slow wave sleep is important for health.

Probable Bruxism and Psychological Issues among Dental Students in Serbia during the COVID-19 Pandemic

The COVID-19 pandemic has drastically changed the routine way of life, having consequences in many segments of life, including dental practice and education. The aim of this study was to evaluate the frequency of probable bruxism in a sample of dental students in Serbia and to estimate the potential association between psychological factors related to the COVID-19 pandemic and the presence of bruxism. A cross-sectional study included 178 dental students in Serbia, who were interviewed using a specially-designed self-administered online questionnaire, which consisted of three sections, and after that, a clinical examination for the presence of bruxism symptoms in the oral cavity. Psychological status was evaluated using the Depression, Anxiety and Stress Scale-21 (DASS-21) and the Fear of COVID-19 Scale (FCV-19S). Saliva samples were taken to analyze salivary cortisol levels. The prevalence of probable bruxism was 34.8%. Respondents with probable bruxism had significantly higher DASS-21 and FCV-19S scores and mean values of salivary cortisol compared to non-bruxers. A history of COVID-19 infection, high stress, and fear of COVID-19 scores were associated with the presence of probable bruxism. The findings suggest that the COVID-19 pandemic has had a great psychological impact and impact on the presence and worsening of bruxism symptoms in a sample of dental students in Serbia.

Exploring the relationship between meaningful conditioned pain modulation and stress system reactivity in healthy adults following exposure to the cold pressor task

BACKGROUND

The sympathetic nervous system (SNS) and hypothalamic-pituitary-adrenal (HPA) axis have been implicated in conditioned pain modulation (CPM). As there has recently been a push to identify meaningful CPM responses based on ± 2 SEM of the test stimulus, we sought to evaluate if meaningful CPM had relationships with both SNS and HPA axis reactivity.

METHODS

50 university-aged healthy participants (25 males, 25 females) underwent evaluation of pressure pain detection threshold (PPDT), conditioned pain modulation (CPM), galvanic skin response (GSR) and salivary cortisol before and after a cold pressor test (CPT). Meaningful CPM was evaluated based on change ±2 SEM of baseline PPDT to classify participants as experiencing inhibition of pain, facilitation, or non-response.

RESULTS

As a group, there were no significant changes in PPDT or salivary cortisol after exposure to noxious cold. GSR was significantly elevated from baseline values during the CPT, and 10 min after (p < 0.001). When meaningful CPM was assessed, only 30% of participants experienced inhibitory CPM. Within this group, there was a large positive correlation ranging from r = 0.63 to 0.69 (p < 0.01) between CPM and the absolute change in GSR from baseline to immersion, and the immediate 5 min after immersion.

CONCLUSIONS

This work continues to support the growing body of literature suggesting that CPM is not universally experienced. Inhibitory CPM may be associated with an increase in SNS activity for healthy participants in reaction to noxious cold. Future work is required to ascertain individual characteristics (e.g., age, sex) that relate to CPM responses.

Diurnal Salivary Cortisol in Relation to Body Composition and Heart Rate Variability in Young Adults

OBJECTIVE

Chronic stress has been related to impaired body composition (bone, muscle, adipose tissue), and disturbed autonomic nervous system (ANS), the latter regulated by hypothalamic-pituitary-adrenal (HPA) axis. Our objective was to investigate the relationship between salivary cortisol, body composition and heart rate variability (HRV-highly influenced by ANS), in a young student population.

METHODS

Body composition and HRV parameters were measured using two portable devices based on multi-frequency bioelectrical impedance and photoplethysmography. Body composition included measurement of bone, lean/muscle and adipose tissues. HRV included time domain and frequency domain indices. Salivary cortisol, immediately after awakening, 60 min post awakening and late night was collected and analyzed by ELISA.

RESULTS

Participants included n = 43 healthy university students (39 women, 4 men); 21.1 ± 1.3 years, BMI = 21.8 ± 3.4 kg/m². Skeletal muscle was reduced in most of the participants, bone mass was at the lower normal range, while the fat tissue parameters were normal with only 7% participants being overweight. Cortisol and HRV parameters of sympathetic predominance (low frequency-LF and low frequency/high frequency ratio-LF/HF) were significantly associated with higher fat tissue parameters (fat mass-FM% and intramuscular adipose tissue-IMAT%) (p <0.001 and p = 0.035, respectively) and with lower skeletal muscle (p = 0.002) and bone mass (p = 0.025).

CONCLUSIONS

The results point to a role of cortisol and ANS in the control of all three body composition compartments, suggesting that the stress can result in adverse effects on body composition, even in young, apparently healthy individuals.

Reference intervals and values for fecal cortisol, aldosterone, and the ratio of cortisol to dehydroepiandrosterone metabolites in four species of cetaceans

The goal of the current study was to create reference intervals and values for several common and one potential novel physiological indicators of animal welfare for four species of cetaceans. The subjects included 189 bottlenose dolphins (Tursiops truncatus), 27 Indo-Pacific bottlenose dolphins (Tursiops aduncus), eight Pacific white-sided dolphins (Lagenorhynchus obliquidens), and 13 beluga whales (Delphinapterus leucas) at Alliance of Marine Mammal Parks and Aquariums and/or Association of Zoos and Aquariums accredited facilities. During two sampling time periods between July and November of 2018 and between January and April of 2019, fecal samples were collected weekly for five weeks from all animals. Samples were processed and analyzed using enzyme immunoassay for fecal cortisol, aldosterone, and dehydroepiandrosterone (DHEA) metabolites. Linear mixed models were used to examine demographic and time factors impacting hormone metabolite concentrations. Age, sex, and time of year were all significant predictors for some of the models (p < 0.01). An iOS mobile application ZooPhysioTrak was created for easy access to species-specific reference intervals and values accounting for significant predictors. For facilities without access to this application, additional reference intervals and values were constructed without accounting for significant predictors. Information gained from this study and the use of the application can provide reference intervals and values to make informed management decisions for cetaceans in zoological facilities.

Trajectories of Depressive Symptoms and Anxiety during Pregnancy and Associations with Pregnancy Stress

The purposes of this study were to investigate the trajectory groups of depressive symptoms and anxiety in women during pregnancy and to identify the factors associated with those groups. Participants were recruited from the outpatient clinic of a women's health hospital in Seoul, Korea. Pregnant women (n = 136) completed a survey questionnaire that included questions on depressive symptoms, anxiety, and pregnancy stress; additionally, their saliva was tested for cortisol hormone levels three times during their pregnancies. The group-based trajectory modeling approach was used to identify latent trajectory groups. Ordinal logistic regressions were used to explore the association of latent trajectory groups with sociodemographic factors and pregnancy stress. Three trajectory groups of depressive symptoms were identified: low-stable (70%), moderate-stable (25%), and increased (5%). Four trajectory groups of anxiety were identified: very low-stable (10%), low-stable (67%), moderate-stable (18%), and high-stable (5%). The only factor associated with both the depressive symptoms and anxiety trajectory groups was pregnancy stress (p < 0.001). Most participants showed stable emotional status; however, some participants experienced higher levels of depressive symptoms and anxiety related to higher pregnancy stress. These pregnant women may need additional care from healthcare providers to promote their wellbeing during pregnancy.

Sensory processing and cortisol at age 4 years: Procedural pain-related stress in children born very preterm

Children born preterm display altered sensory processing, which may manifest as hyper- and/or hypo-sensitivity to sensory information. In this vulnerable population, exposure to neonatal pain-related stress is associated with altered stress regulation, as indexed by alterations in cortisol levels. It is unknown whether sensory processing behaviors are also affected by early life adversity, and whether dysregulated cortisol is related to sensory processing problems in preterm children. We examined relationships between neonatal pain-related stress, sensory processing profiles and cortisol levels at age 4 years, and whether pathways were sex-specific. In a longitudinal prospective cohort study, N = 146 infants born 24-32 weeks gestational age were recruited from BC Women's Hospital, Vancouver, BC, Canada; neonatal factors were collected from daily chart review. At age 4 years, saliva to assay cortisol was collected three times across cognitive assessment (pre-test, during, end) and parents completed the Short Sensory Profile questionnaire. Using generalized linear modeling, independent of other neonatal factors, higher number of invasive procedures (pain/stress) was associated with more sensory processing problems (total, hypo- and hyper-sensitivity) for girls only. After accounting for neonatal factors, greater cortisol output across the assessment was associated with more total sensory processing problems in girls only, and hypersensitivity to sensory input in both boys and girls. Findings suggest that in children born very preterm, how a child responds to sensory input and cortisol reactivity to stress are related but may have different precursors. Girls may be somewhat more susceptible to neonatal pain-related stress exposure in relation to sensory processing at preschool age.

Cortisol Measurements in Cushing's Syndrome: Immunoassay or Mass Spectrometry?

Determination of cortisol levels in the urine (24 hours urine free cortisol), saliva (late-night), or serum (total cortisol after dexamethasone suppression) is recommended to screen for Cushing's syndrome (CS). This review focuses on the differences between the frequently used cortisol-antibody immunoassay-based methods and the highly specific mass-spectrometry-based methods that are progressively being employed in clinical laboratories for CS screening. The particular characteristics of cortisol metabolism and the lack of specificity of the immunoassays cause marked differences between both methods that are in turn highly dependent on the biological matrix, in which the cortisol is measured. Understanding the origin of these differences is essential for the interpretation of these results. Although cross-reactivity with endogenous steroids leads to grossly inaccurate results of immunoassay measurements of cortisol in the saliva and urine, preliminary evidence suggests that the clinical sensitivity of CS screening using immunoassays may be similar to CS screening using mass spectrometry. However, mass spectrometry offers more accurate results and considerably reduced variation across laboratories, while avoiding false-positive results. Moreover, mass spectrometry can overcome some common diagnostic challenges, such as identification of exogenous corticosteroids or simultaneous assessment of appropriate dexamethasone levels in suppression tests. Further, comprehensive mass spectrometry-based profiling of several steroid metabolites may be useful for discriminating among different subtypes of CS. Finally, this review discusses the main preanalytical factors that could cause variations in cortisol measurements and their influence on the reliability of the results.

Effects of Breastfeeding on Stress Measured by Saliva Cortisol Level and Perceived Stress

Purpose: The effects of breastfeeding on postpartum depression symptoms and stress using physiological measures require investigation.

Background: Breastfeeding suppresses the secretion of cortisol. Oxytocin levels correlate negatively with symptoms of postpartum depression.

Aim: To investigate the effects of breastfeeding on stress and postpartum depression.

Methods: We examined 79 breastfeeding women using the Edinburgh Postnatal Depression Scale, the Perceived Stress Scale-10, and the Breastfeeding Self-Efficacy Scale, and measured the salivary cortisol levels before and after breastfeeding.

Findings: There was a negative correlation between the duration of suckling and changes in salivary cortisol levels following breastfeeding (r_s = −0.333, p < 0.05). Salivary cortisol levels immediately following breastfeeding were significantly lower compared to mothers who used mixed feeding methods (p < 0.001). Breastfeeding mothers had lower perceived stress than mothers using mixed feeding methods (β = −0.260, p < 0.05). There was no association between breastfeeding and postpartum depression; however, there was an association between postpartum depression and perceived stress (β = 0.526, p < 0.001).

Conclusion: Salivary cortisol levels significantly decreased following breastfeeding, with longer suckling times correlating with lower cortisol levels. Breastfeeding reduced stress and increased breastfeeding self-efficacy.

The diagnostic utility of late night salivary cortisol (LNSF) and cortisone (LNSE) in Cushing's syndrome

BACKGROUND

Measurement of late night salivary cortisol (LNSF) is useful in the identification of cyclical Cushing's syndrome (CS); the usefulness of its metabolite cortisone (late night salivary cortisone, LNSE) is less well described.

AIM

The aim of this study was to determine the utility of measuring LNSE in patients with confirmed CS compared with other diagnostic tests and to analyse serial LNSF measurements for evidence of variable hormonogenesis.

METHODS

This was a retrospective observational study including patients with confirmed CS in whom LNSF and LNSE were measured.

RESULTS

Twenty-three patients with confirmed CS were included, 21 with Cushing's disease. LNSF had a sensitivity of 92%, LNSE 87% and combined LNSF/LNSE 94% per sample. Four patients had cyclical hormonogenesis, when the definition of one trough and two peaks was applied to LNSF measurements, and a fifth patient fell just outside the criteria. Six patients had evidence of variable hormonogenesis, defined as doubling of LNSF concentration on serial measurements. Sensitivity of 24-h urinary free cortisol (UFC) was 89% per collection. Sixteen patients had simultaneous measurements of LNSF and UFC; in three patients, they provided discordant results.

CONCLUSION

LNSF appears more sensitive than LNSE and UFC in the diagnosis of CS, combining LNSF and LNSE results leads to superior sensitivity. Half of our cohort had evidence of cyclical or variable hormonogenesis. Fluctuations in LNSF did not always correlate with changes in UFC concentration, emphasising the importance of performing more than one screening test, particularly if pretest clinical suspicion is high.

Cortisol profiles and clinical severity in MECP2 duplication syndrome

BACKGROUND

MECP2 duplication syndrome (MDS) is a rare X-linked genomic disorder primarily affecting males which is caused by interstitial chromosomal duplications at Xq28 encompassing the MECP2 gene. Core clinical features of MDS include choreiform movements, progressive spasticity, recurrent respiratory infections, developmental delays in the first 6 months of life, hypotonia, vasomotor disturbances, constipation, drooling, and bruxism. Prior studies suggest that HPA axis activity may be altered in MDS and measures of HPA axis activity may offer insight into disease severity.

METHODS

To ascertain whether cortisol profiles are a potential biomarker of clinical severity, diurnal profiles of cortisol and the cortisol awakening response were examined from saliva samples in 31 participants with MDS (ages 2-24 years), and 27 of these samples were usable. Documentation of a positive diagnostic test for MECP2 duplication was required for entry into the study. Samples were collected on each of two consecutive weekdays at four time points during the day: immediately after waking, 30 min after waking, between 3 and 4 PM, and in the evening before bedtime. Correlations with duplication size, clinical severity, sleep problems, and behavior were also examined.

RESULTS

Results revealed that a majority of participants with MDS exhibit a declining cortisol awakening response (n = 17). A declining CAR was significantly associated with increased clinical severity scores (r = - .508; p = .03), larger duplication size, waking later, and an increased number of hospitalizations for infections.

CONCLUSIONS

Future mechanistic studies will have to determine whether the declining CAR in MDS is attributable to problems with "flip-flop switching" of regional brain activation (involving the suprachiasmatic nucleus and the hippocampus, and the HPA axis) that is responsible for the switch from reduced to increased adrenal sensitivity. Taken together, results suggest the possibility that cortisol profiles could potentially be a biomarker of clinical severity and utilized for the purposes of patient stratification for future clinical trials in MDS.

Medical Diagnostic Tests: A Review of Test Anatomy, Phases, and Statistical Treatment of Data

Diagnostic tests are approaches used in clinical practice to identify with high accuracy the disease of a particular patient and thus to provide early and proper treatment. Reporting high-quality results of diagnostic tests, for both basic and advanced methods, is solely the responsibility of the authors. Despite the existence of recommendation and standards regarding the content or format of statistical aspects, the quality of what and how the statistic is reported when a diagnostic test is assessed varied from excellent to very poor. This article briefly reviews the steps in the evaluation of a diagnostic test from the anatomy, to the role in clinical practice, and to the statistical methods used to show their performances. The statistical approaches are linked with the phase, clinical question, and objective and are accompanied by examples. More details are provided for phase I and II studies while the statistical treatment of phase III and IV is just briefly presented. Several free online resources useful in the calculation of some statistics are also given.

Basal cortisol, cortisol reactivity, and telomere length: A systematic review and meta-analysis

The objective of the present study is to synthesize the existing empirical literature and perform a meta-analysis of published data on the relationship between cortisol and telomere length. We systematically searched studies that examined the relationship between cortisol and telomere length in humans on electronic databases and screened reference sections of included articles. Fourteen studies were included in the meta-analysis, with effect sizes being extracted for two cortisol measures: basal cortisol levels and cortisol reactivity to acute psychological stress. Results from random effects models showed that basal cortisol levels (13 effect sizes from 12 cross-sectional studies, N = 3675 participants) were not significantly correlated with telomere length (r =-0.05, 95% CI [-0.11, 0.02]). Further, results stratified by the specimen type for cortisol measurement (i.e., saliva, urine, blood) showed that none of the three basal cortisol level measures were correlated with telomere length. However, we found a statistically significant correlation between salivary cortisol reactivity to acute psychosocial stress (6 cross-sectional studies, N = 958 participants) and telomere length (r = -0.13, 95% CI [-0.23, -0.03]). Subgroup analyses revealed that correlations between salivary cortisol reactivity and telomere length were more evident in studies conducted among children (vs. adults) and in studies that included female participants only (vs. both genders). However, the small number of available studies limits the conclusions derived from subgroup analyses, and more studies are needed before moderator effects can be properly established. Overall, findings of this study support the existence of a relationship between cortisol reactivity and telomere shortening.

Rodent models of mental illness in polycystic ovary syndrome: the potential role of hypothalamic-pituitary-adrenal dysregulation and lessons for behavioral researchers

Polycystic ovary syndrome (PCOS) is the most commonly diagnosed endocrine disorder in women of reproductive age, with phenotypes including ovarian and metabolic dysfunctions. Women with PCOS also show increased rates of mental illness, dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, and altered responsiveness to stressors that may contribute to the higher rates of mental illness, specifically depression and anxiety. Animal models of PCOS have provided insight into the ovarian and metabolic mechanisms that underlie the syndrome, and several models have been used to study the behavioral consequences associated with PCOS in the laboratory. Several studies in rodent models of PCOS demonstrate changes in anxiety-like behavior, but researchers often neglect to report procedural details or behavioral data crucial to interpreting the differences observed in those studies. Additionally, the impact of potential HPA dysregulation in animal models of PCOS may influence behavioral findings, although only three studies to date have examined this. As such, researchers should consider and report stress-associated variables (e.g., time of day, light/dark cycle, light intensity, housing, and procedures to control experimenter and litter effects) that may influence depression- and anxiety-like behaviors in rodents. This review will summarize the behavioral and HPA-related studies in women with PCOS and rodent models of the disease, and provide considerations for future studies.

Psychotherapeutic treatment and HPA axis regulation in posttraumatic stress disorder: A systematic review and meta-analysis

Posttraumatic stress disorder (PTSD) has been associated with dysregulation of the hypothalamic-pituitary- adrenal (HPA) axis. Research over the past years has investigated potential changes of these alterations in the context of psychotherapy. Yet, no systematic review has been conducted. To summarize the current state of research on psychotherapy and HPA hormones, namely cortisol, dehydroepiandrosterone and its sulfate form (DHEA(S)), we searched for studies investigating predictions or changes in hormones over treatment course within the databases PubMed, Scopus, Medline, PsychINFO, Pilots/ProQuest, and Web of Science, and in the grey literature up to May 2018. Controlled and uncontrolled trials investigating adult samples with a clinical status of PTSD were eligible for inclusion. Twelve studies (428 participants) were included. Study quality was overall sufficient. Hormone assessment designs differed considerably. Treatment efficacy on PTSD symptom reduction was mostly high, but predictions of pre-treatment hormone concentrations on treatment efficacy were largely non-significant. Changes from pre- to post-test in basal cortisol (g = -0.07, 95% CI = -0.36; 0.21) and in the cortisol awakening response (g = -0.07, 95% CI = -0.48; 0.35) were also non-significant. Future studies require comparable designs and need to be sufficiently powered to be able to detect potential associations with HPA regulation.

Child sex moderates the relationship between cortisol stress reactivity and symptoms over time

BACKGROUND

Past work suggests that individual differences in stress reactivity have implications for the development of psychopathology; in particular, females' stress reactivity appears more closely tied to internalizing symptoms than males' reactivity. Conversely, males who are under-reactive to threat may be at risk for externalizing problems. However, little is known about when such differences may emerge, although this knowledge could have implications for early prevention.

METHODS

Cortisol reactivity to a laboratory stressor was assessed in 409 three-year-old children (201 boys), along with parent-reported children's internalizing (anxiety and depression) and externalizing (oppositional-defiant and attention problems and hyperactivity) symptoms. Parent-reported symptoms were re-collected at child ages 5 (N = 379) and 8 (N = 364). Multilevel modelling was used to investigate whether the relationship between cortisol reactivity and symptoms differed between boys and girls over time.

RESULTS

Girls with lower cortisol reactivity showed a negative association between depressive symptoms and time, while girls with higher reactivity showed no such association. No interaction between sex and cortisol reactivity was found for anxious symptoms. Boys with higher cortisol reactivity showed a negative association between symptoms and time, while boys with lower cortisol reactivity showed no such association. Time and ADHD symptoms were unrelated for boys, regardless of their cortisol reactivity.

CONCLUSIONS

Findings suggest that the implications of stress reactivity indexed via cortisol vary for boys and girls, as well as for different symptom manifestations.

Specific detection of stable single nucleobase mismatch using SU-8 coated silicon nanowires platform

Novel microarray platform for single nucleotide polymorphisms (SNPs) detection has been developed using silicon nanowires (SiNWs) as support and two different surface modification methods for attaining the necessary functional groups. Accordingly, we compared the detection specificity and stability over time of the probes printed on SiNWs modified with (3-aminopropyl)triethoxysilane (APTES) and glutaraldehyde (GAD), or coated with a simpler procedure using epoxy-based SU-8 photoresist. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used for comparative characterization of the unmodified and coated SiNWs. The hybridization efficiency was assessed by comprehensive statistical analysis of the acquired data from confocal fluorescence scanning of the manufactured biochips. The high detection specificity between the hybridized probes containing different mismatch types was demonstrated on SU-8 coating by one way ANOVA test (adjusted p value *** < .0001). The stability over time of the probes tethered on SiNWs coated with SU-8 was evaluated after 1, 4, 8 and 21 days of probe incubation, revealing values for coefficient of variation (CV) between 2.4% and 5.6%. The signal-to-both-standard-deviations ratio measured for SU-8 coated SiNWs platform was similar to the commercial support, while the APTES-GAD coated SiNWs exhibited the highest values.