Hair Cortisol in Twins: Heritability and Genetic Overlap with Psychological Variables and Stress-System Genes

Hair hormone data from Syrian refugee children: Perspectives from a two-year longitudinal study

For numerous issues of convenience and acceptability, hair hormone data have been increasingly incorporated in the field of war trauma and forced displacement, allowing retrospective examination of several biological metrics thought to covary with refugees' mental health. As a relatively new research method, however, there remain several complexities and uncertainties surrounding the use of hair hormones, from initial hair sampling to final statistical analysis, many of which are underappreciated in the extant literature, and restrict the potential utility of hair hormones. To promote awareness, we provide a narrative overview of our experiences collecting and analyzing hair hormone data in a large cohort of Syrian refugee children (n = 1594), across two sampling waves spaced 12 months apart. We highlight both the challenges faced, and the promising results obtained thus far, and draw comparisons to other prominent studies in this field. Recommendations are provided to future researchers, with emphasis on longitudinal study designs, thorough collection and reporting of hair-related variables, and careful adherence to current laboratory guidelines and practices.

On the complex relationship between resilience and hair cortisol levels in adolescence despite parental physical abuse: a fourth wave of resilience research

Introduction

To understand the family's role in adolescents' mental health development and the connection to neurodevelopmental disorders related to experienced parental physical abuse, we first explored resilience pathways longitudinally and secondly, connected the identified patterns to adolescents' hair cortisol levels that are rooted in the hypothalamic-pituitary-adrenal axis as the main stress response system and connected brain structure alterations.

Methods

We analyzed longitudinal online questionnaire data for three consecutive high school years (from seventh to ninth grade) and four survey waves from a representative sample of n = 1609 high school students in Switzerland on violence-resilience pathways. Furthermore, we collected students' hair samples from a subsample of n = 229 at survey wave 4. About 30% of the participating adolescents had been physically abused by their parents. Out of the overall sample, we drew a subsample of adolescents with parental abuse experiences (survey wave 1 n = 509; survey wave 2 n = 506; survey wave 3 n = 561; survey wave 4 n = 560).

Results

Despite the odds, about 20-30% of adolescents who have experienced parental physical abuse escaped the family violence cycle and can be called resilient. By applying a person-oriented analytical approach via latent class and transition analysis, we longitudinally identified and compared four distinct violence-resilience patterns. We identified violence resilience as a multidimensional latent construct, which includes hedonic and eudaimonic protective and risk indicators. Because resilience should not solely be operationalized based on the lack of psychopathology, our latent construct included both feeling good (hedonic indicators such as high levels of self-esteem and low levels of depression/anxiety and dissociation) and doing well (eudaimonic indicators such as high levels of self-determination and self-efficacy as well as low levels of aggression toward peers).

Discussion

The present study confirmed that higher cortisol levels significantly relate to the comorbid pattern (internalizing and externalizing symptoms), and further confirmed the presence of lasting alterations in brain structures. In this way, we corroborated the insight that when studying the resilience pathways and trajectories of abused adolescents, biological markers such as hair cortisol significantly enhance and deepen the understanding of the longitudinal mechanisms of psychological markers (e.g., self-determination, self-esteem, self-efficacy) that are commonly applied in questionnaires.

Hair cortisol and self-perceived stress in adolescents with multi-system functional somatic disorders

BACKGROUND

Long-term stress causing altered hypothalamic-pituitary-adrenal (HPA) axis dynamics with cortisol dysfunction may be involved in the pathophysiology of functional somatic disorders (FSD), but studies on adolescents with multi-system FSD are lacking. Therefore, we investigated: 1) whether hair cortisol concentration (HCC) differentiates adolescents with multi-system FSD from a) a population-based sample and b) a subgroup derived from the sample reporting a high physical symptom load, and 2) whether FSD population HCC is associated with primary symptom presentations and self-perceived stress.

METHODS

We used data from a clinical sample with multi-system FSD (N = 91, age 15-19 years) and a population-based sample (N = 1,450, age 16-17 years) including a subgroup with top 10% total scores on physical symptoms (N = 147). Density plots and multiple linear regression were applied to compare HCC between groups. In the clinical sample, multiple linear regression was employed to assess the association between HCC and primary symptom clusters and self-perceived stress.

RESULTS

Median HCC was lower in the clinical sample than in the population-based sample (β = 0.80 (95%CI: 0.66, 0.97)), but not significantly different from median HCC in the derived subgroup (β = 0.84 (95%CI: 0.66, 1.07)). In the clinical sample, HCC was not significantly associated with primary symptom clusters (F(2, 82) = 0.13, p = 0.88) or self-perceived stress (F(4, 83) = 1.18, p = 0.33).

CONCLUSION

Our findings indicate that HCC is lowered in adolescents with multi-system FSD but not significantly associated with primary symptom presentations or self-perceived stress. Future studies including multiple measures of HPA axis dynamics alongside psychological measures may further elucidate the role of long-term stress in FSD.

TRIAL REGISTRATION

The AHEAD study was pre-registered at ClinicalTrials.gov (NCT02346071), 26/01/2015.

Long-term cortisol secretion in attention deficit hyperactivity disorder: roles of sex, comorbidity, and symptom presentation

Low activity of the hypothalamic-pituitary-adrenal axis (HPAA) has been found in children with attention deficit hyperactivity disorder (ADHD). The condition may be related to the reduced attention regulation capacity and/or to comorbid oppositional defiant or conduct disorder (ODD/CD). Sex differences are probable but not sufficiently studied. We analyzed the HPAA activity and sympathetic nervous system reactivity (SR) in children with ADHD while accounting for ADHD symptom presentation, comorbidity, and sex differences. The sample comprised 205 children, 98 (61 boys, 37 girls) with ADHD and 107 (48 boys, 59 girls) healthy controls. DSM-5 phenotypic symptom presentation and comorbid ODD/CD were assessed using clinical interviews. Hair cortisol concentration (HCC) was used to assess the long-term, cumulative activity of the HPAA. SR was assessed via skin conductance response (SCR). For control purposes, comorbid internalizing symptoms and indicators of adverse childhood experiences (ACE) were assessed. Children were medication naive. Boys presenting with predominantly inattentive symptoms (ADHD-I) showed lower HCC than healthy boys. Girls presenting with combined symptoms (ADHD-C) showed higher HCC than did healthy girls (p's < 0.05, sex-by-group interaction, F (2,194) = 4.09, p = 0.018). Boys with ADHD plus ODD/CD showed a blunted SR (p < 0.001, sex-by-group interaction, F (2,172) = 3.08, p = 0.048). Adjustment for ACE indicators led to non-significant differences in HCC but did not affect differences in SR. HCC constitutes an easily assessable, reliable, and valid marker of phenotypic ADHD-related features (i.e. symptom presentation and comorbidity). It indicates more homogenous subgroups of ADHD and might point to specifically involved pathophysiological processes.

Determination of cortisone and cortisol in human scalp hair using an improved LC-MS/MS-based method

OBJECTIVES

Human scalp hair is an easily available but complex matrix for determination of cortisone and cortisol, and has been shown to reflect long-term glucocorticoid exposure. Hair glucocorticoid analysis has been used to detect hypo- and hypercortisolism. In this study, we describe the development and validation of a LC-MS/MS method for quantification of cortisone and cortisol in human scalp hair, and provide a novel approach for analysis and interpretation of the results.

METHODS

Improved sample preparation using pulverization and solid phase extraction allowed for low sample volumes (10 mg). Baseline chromatographic separation without matrix interference was achieved by reversed phase chromatography and MRM measurement in negative ion mode. Run-to-run time was 8 min. Mixed model analyses were performed to create individual patterns of cortisone and cortisol concentrations.

RESULTS

Matrix matched calibration curves showed excellent linearity up to 100 pg (analyte)/mg (hair) for both cortisone and cortisol (R2>0.995). LLOQ was 1.5 and 1.0 pg/mg for cortisone and cortisol, respectively. Matrix effect was negligible for hair color (recoveries 95-105 %). Cortisone and cortisol concentrations decreased from proximal to distal hair segments, following a predictable, but subject-specific pattern, with less individual variation for cortisone than for cortisol.

CONCLUSIONS

This improved LC-MS/MS method is able to accurately quantify cortisone and cortisol in human hair with minimum matrix interference. This new way of data analysis and interpretation including individual patterns of cortisone and cortisol will be of help with detection of pathological concentrations in both the high - and the low ranges of glucocorticoids.

The Development of Stress Reactivity and Regulation in Children and Adolescents

Adversity experienced in early life can have detrimental effects on physical and mental health. One pathway in which these effects occur is through the hypothalamic-pituitary-adrenal (HPA) axis, a key physiological stress-mediating system. In this review, we discuss the theoretical perspectives that guide stress reactivity and regulation research, the anatomy and physiology of the axis, developmental changes in the axis and its regulation, brain systems regulating stress, the role of genetic and epigenetics variation in axis development, sensitive periods in stress system calibration, the social regulation of stress (i.e., social buffering), and emerging research areas in the study of stress physiology and development. Understanding the development of stress reactivity and regulation is crucial for uncovering how early adverse experiences influence mental and physical health.

Risk and resilience in Syrian refugee children: A multisystem analysis

Refugee children are often exposed to substantial trauma, placing them at increased risk for mental illness. However, this risk can be mitigated by a capacity for resilience, conferred from multiple ecological systems (e.g., family, community), including at an individual biological level. We examined the ability of hair cortisol concentrations and polygenic scores for mental health to predict risk and resilience in a sample of Syrian refugee children (n = 1359). Children were categorized as either at-risk or resilient depending on clinical thresholds for posttraumatic stress disorder, depression, and externalizing behavior problems. Logistic regression was used to examine main and interacting effects while controlling for covariates. Elevated hair cortisol concentrations were significantly associated with reduced resilience (odds ratio (OR)=0.58, 95%CI [0.40, 0.83]) while controlling for levels of war exposure. Polygenic scores for depression, self-harm, and neuroticism were not found to have any significant main effects. However, a significant interaction emerged between hair cortisol and polygenic scores for depression (OR=0.04, 95%CI [0.003 0.47]), suggesting that children predisposed to depression were more at risk for mental health problems when hair cortisol concentrations were high. Our results suggest that biomarkers (separately and in combination) might support early identification of refugee children at risk for mental health problems.

Reliability of diurnal salivary cortisol metrics: A meta-analysis and investigation in two independent samples

Stress-induced dysregulation of diurnal cortisol is a cornerstone of stress-disease theories; however, observed associations between cortisol, stress, and health have been inconsistent. The reliability of diurnal cortisol features may contribute to these equivocal findings. Our meta-analysis (5 diurnal features from 11 studies; total participant n = 3307) and investigation (15 diurnal cortisol features) in 2 independent studies (St. Louis Personality and Aging Network [SPAN] Study, n = 147, ages 61-73; Minnesota Longitudinal Study of Risk and Adaptation [MLSRA] Study, n = 90, age 37) revealed large variability in the day-to-day test-retest reliability of diurnal features derived from salivary cortisol data (i.e., ICC = 0.00-0.75). Collectively, these data indicate that some commonly used diurnal cortisol features have poor reliability that is insufficient for individual differences research (e.g., cortisol awakening response) while others (e.g., area under the curve with respect to ground) have fair-to-good reliability that could support reliable identification of associations in well-powered studies.

Five-Factor Model Personality Traits and 24-hour Urinary Cortisol in the Baltimore Longitudinal Study of Aging

Stress is implicated in models of personality and health as a mechanism that explains why traits like conscientiousness and neuroticism are associated with long-term health outcomes. Evidence for an association between personality and cortisol, a biological marker of stress, however, has been inconsistent. This study examined the association between Five-Factor Model personality traits and 24-h urinary cortisol (operationalised as a ratio of urinary free cortisol to creatinine) measured up to 12 times over intervals as long as 30 years in the Baltimore Longitudinal Study of Aging (M_age  = 61.21, SD = 15.46; 49% female). There was a modest association between conscientiousness and lower mean-level cortisol that was attenuated only slightly in the fully-adjusted model. Neuroticism and the other traits were unrelated to cortisol levels, and none of the traits was related to cortisol change over time. The null association for neuroticism suggests that its relation with long-term health may be primarily through pathways other than cortisol. The modest association between conscientiousness and 24-h urinary cortisol replicates a previous finding with a longer-term measure of cortisol measured from hair, which calls for more research on the robustness and replicability of this finding. Cortisol may be one pathway through which conscientiousness is associated with health outcomes.

An in-laboratory stressor reveals unique genetic variation in child cortisol output

Dysregulation of biological stress response, as measured by cortisol output, has been a primary candidate mechanism for how social experiences become biologically embedded. Cortisol is the primary output of the hypothalamic pituitary adrenal (HPA) axis. Cortisol levels vary systematically across the day and change in response to both sudden, acute stress experiences as well as prolonged exposure to environmental stress. Using data from 8- to 15-year-old twins in the Texas Twin Project, we investigate the extent to which genetic influences are shared across different measures of cortisol output: chronic cortisol accumulations in hair (n = 1,104), diurnal variation in salivary output (n = 488), and salivary response to a standardized, acute in-laboratory stressor (n = 537). Multivariate twin models indicate that genetic factors regulating cortisol response to the in-laboratory stressor are separable from those regulating baseline cortisol levels, naturally occurring diurnal variation in cortisol, and hair cortisol levels. These findings illustrate that novel environments can reveal unique genetic variation, reordering people in terms of their observed phenotype rather than only magnifying or mitigating preexisting differences. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Association between the timing of family socioeconomic deprivation and adolescence hair cortisol among adolescent twins: A study of the genetic and environmental processes involved

BACKGROUND

While evidence shows that lower socioeconomic status (SES) is related to dysregulated hair cortisol concentration (HCC), the genetic and environmental processes underlying this association remain understudied.

OBJECTIVES

(1) to examine whether childhood and adolescence SES are phenotypically related to late adolescence HCC and to what extent these associations are explained by common underlying genetic factors (2) to estimate whether the genetic and environmental etiology of HCC varies according to SES and the timing of these experiences.

METHODS

Participants were 422 twin pairs for whom SES was measured in childhood (ages 0-5 years) and adolescence (age 14 years). Hair cortisol was assessed at age 19.

RESULTS

Additive genetic factors explained 39% of variability in HCC, whereas nonshared environmental factors accounted for the remaining 61%. A significant negative association emerged between HCC and family SES assessed in adolescence (β=-.11,p = .02), which was entirely explained by common underlying environmental influences. We also found evidence of stronger genetic contributions to HCC among youths who lived in more disadvantaged households during childhood in comparison to those from wealthier backgrounds.

CONCLUSIONS

This study provides first-time evidence that the association between adolescence SES and HCC is environmentally-explained and that genetic influences underlying HCC are not uniformly distributed across the family SES continuum measured during childhood. These findings may pave the way for a fuller understanding of the impact of early adversity on HPA axis activity.

Association of polygenic risk scores and hair cortisol with mental health trajectories during COVID lockdown

The COVID-19 pandemic is a global stressor with inter-individually differing influences on mental health trajectories. Polygenic Risk Scores (PRSs) for psychiatric phenotypes are associated with individual mental health predispositions. Elevated hair cortisol concentrations (HCC) and high PRSs are related to negative mental health outcomes. We analyzed whether PRSs and HCC are related to different mental health trajectories during the first COVID lockdown in Germany. Among 523 participants selected from the longitudinal resilience assessment study (LORA), we previously reported three subgroups (acute dysfunction, delayed dysfunction, resilient) based on weekly mental health (GHQ-28) assessment during COVID lockdown. DNA from blood was collected at the baseline of the original LORA study (n = 364) and used to calculate the PRSs of 12 different psychopathological phenotypes. An explorative bifactor model with Schmid-Leiman transformation was calculated to extract a general genetic factor for psychiatric disorders. Hair samples were collected quarterly prior to the pandemic for determining HCC (n = 192). Bivariate logistic regressions were performed to test the associations of HCC and the PRS factors with the reported trajectories. The bifactor model revealed 1 general factor and 4 sub-factors. Results indicate a significant association between increased values on the general risk factor and the allocation to the acute dysfunction class. The same was found for elevated HCC and the exploratorily tested sub-factor "childhood-onset neurodevelopmental disorders". Genetic risk and long-term cortisol secretion as a potential indicator of stress, indicated by PRSs and HCC, respectively, predicted different mental health trajectories. Results indicate a potential for future studies on risk prediction.

Persistence of Anxiety/Depression Symptoms in Early Adolescence: A Prospective Study of Daily Life Stress, Rumination, and Daytime Sleepiness in a Genetically Informative Cohort

In this prospective study of mental health, we examine the influence of three interrelated traits - perceived stress, rumination, and daytime sleepiness - and their association with symptoms of anxiety and depression in early adolescence. Given the known associations between these traits, an important objective is to determine the extent to which they may independently predict anxiety/depression symptoms. Twin pairs from the Queensland Twin Adolescent Brain (QTAB) project were assessed on two occasions (N = 211 pairs aged 9-14 years at baseline and 152 pairs aged 10-16 years at follow-up). Linear regression models and quantitative genetic modeling were used to analyze the data. Prospectively, perceived stress, rumination, and daytime sleepiness accounted for 8-11% of the variation in later anxiety/depression; familial influences contributed strongly to these associations. However, only perceived stress significantly predicted change in anxiety/depression, accounting for 3% of variance at follow-up after adjusting for anxiety/depression at baseline, although it did not do so independently of rumination and daytime sleepiness. Bidirectional effects were found between all traits over time. These findings suggest an underlying architecture that is shared, to some degree, by all traits, while the literature points to hypothalamic-pituitary-adrenal (HPA) axis and/or circadian systems as potential sources of overlapping influence and possible avenues for intervention.

Heritability of Urinary Amines, Organic Acids, and Steroid Hormones in Children

Variation in metabolite levels reflects individual differences in genetic and environmental factors. Here, we investigated the role of these factors in urinary metabolomics data in children. We examined the effects of sex and age on 86 metabolites, as measured on three metabolomics platforms that target amines, organic acids, and steroid hormones. Next, we estimated their heritability in a twin cohort of 1300 twins (age range: 5.7–12.9 years). We observed associations between age and 50 metabolites and between sex and 21 metabolites. The monozygotic (MZ) and dizygotic (DZ) correlations for the urinary metabolites indicated a role for non-additive genetic factors for 50 amines, 13 organic acids, and 6 steroids. The average broad-sense heritability for these amines, organic acids, and steroids was 0.49 (range: 0.25–0.64), 0.50 (range: 0.33–0.62), and 0.64 (range: 0.43–0.81), respectively. For 6 amines, 7 organic acids, and 4 steroids the twin correlations indicated a role for shared environmental factors and the average narrow-sense heritability was 0.50 (range: 0.37–0.68), 0.50 (range; 0.23–0.61), and 0.47 (range: 0.32–0.70) for these amines, organic acids, and steroids. We conclude that urinary metabolites in children have substantial heritability, with similar estimates for amines and organic acids, and higher estimates for steroid hormones.

Parameterizing Toxic Stress in Early Childhood: Maternal Depression, Maltreatment, and HPA-Axis Variation in a Pilot Intervention Study

Adverse experiences superseding a child's capacity to sustain regulation of emotion and adaptive function are theorized to constitute "toxic stressors" when they induce a deleterious biological response within an individual. We ascertained presumptive parameters of toxic stress among 164 low-income infants and toddlers (ages 4-48 months) from 132 families enrolled in Early Head Start (EHS). We randomized a subset of these families into a pilot intervention arm of parenting education (the Incredible Years, TIY), which supplemented the EHS curriculum. Official report child abuse and neglect (CAN) and child behavior were serially ascertained over the course of the study. We observed relatively low associations among maternal depression, CAN, caregiver-child relationship quality, hair cortisol, and adverse child behavioral outcomes. Moreover, despite poverty and the high prevalence (51%) of CAN in this sample, the frequency of clinical-level internalizing and externalizing behavior among the children did not exceed that of the general population, by their parents' report. The pilot supplementation of EHS with TIY improved attendance in group meetings but did not significantly reduce adverse behavioral outcomes or CAN. This study revealed marked independence of standard indices of toxic stress (child maltreatment, maternal depression, caregiver emotional unavailability) which have been presumed to be risk factors for the development of psychopathology. That they were weakly inter-correlated, and only modestly predictive of child behavioral outcomes in this EHS sample, caution against presumptions about the toxicity of individual stressors, highlight the importance of ascertaining risk (and compensatory influences) comprehensively, suggest buffering effects of programs like EHS, and demonstrate the need for greater understanding of what parameterizes resilience in early childhood.

Social Fear in US Infants: The Roles of Hair and Salivary Cortisol

Elevated social fear in infancy poses risk for later social maladjustment and psychopathology. Hair cortisol concentration (HCC), an index of cumulative cortisol exposure, and diurnal salivary cortisol slope, a biomarker of acute stress regulation, have been associated with social fear behaviors in childhood; however, no research has addressed their relations in infancy. Elucidating potential biomarkers of infant social fear behaviors, as well as environmental factors associated with these biomarkers, may grant insights into the ontogeny of fear behaviors that increase risk for internalizing and externalizing psychopathologies later in life. The current study used multiple linear regression to examine if infant HCC, infant diurnal cortisol slope, and income-to-needs ratios (ITN) were differentially associated with observed social fear responses to a Stranger Approach task at 12 months. Using a sample of 90 infants (M _age = 12.26m, SD = 0.81m, 50% female), results indicated that increased infant HCC was associated with increased distress vocalizations during the Stranger Approach task, while steeper diurnal cortisol slope was associated with fewer distress vocalizations. Ordinary least squares path analyses did not reveal group differences between economically strained and non-strained infants in how cortisol measures and social fear responses related. Findings underscore very early psychobiological correlates of fearfulness that may increase risk for fear-related disorders and adverse mental health symptomology across childhood.

No long-term effects of antenatal synthetic glucocorticoid exposure on epigenetic regulation of stress-related genes

Antenatal synthetic glucocorticoid (sGC) treatment is a potent modifier of the hypothalamic-pituitary-adrenal (HPA) axis. In this context, epigenetic modifications are discussed as potential regulators explaining how prenatal exposure to GCs might translate into persistent changes of HPA axis "functioning". The purpose of this study was to investigate whether DNA methylation and gene expression profiles of stress-associated genes (NR3C1; FKBP5; SLC6A4) may mediate the persistent effects of sGC on cortisol stress reactivity that have been previously observed. In addition, hair cortisol concentrations (hairC) were investigated as a valid biomarker of long-term HPA axis activity. This cross-sectional study comprised 108 term-born children and adolescents, including individuals with antenatal GC treatment and controls. From whole blood, DNA methylation was analyzed by targeted deep bisulfite sequencing. Relative mRNA expression was determined by RT-qPCR experiments and qBase analysis. Acute stress reactivity was assessed by the Trier Social Stress Test (TSST) measuring salivary cortisol by ELISA and hairC concentrations were determined from hair samples by liquid chromatography coupled with tandem mass spectrometry. First, no differences in DNA methylation and mRNA expression levels of the stress-associated genes between individuals treated with antenatal sGC compared to controls were found. Second, DNA methylation and mRNA expression levels were neither associated with cortisol stress reactivity nor with hairC. These findings do not corroborate the belief that DNA methylation and mRNA expression profiles of stress-associated genes (NR3C1; FKBP5; SLC6A4) play a key mediating role of the persistent effects of sGC on HPA axis functioning.

Standard Modifiable Cardiovascular Risk Factors Mediate the Association Between Elevated Hair Cortisol Concentrations and Coronary Artery Disease

Background

Increased cortisol exposure is a risk factor for coronary artery disease (CAD). It is not clear to what degree this risk is independent from the standard modifiable risk factors (SMuRFs) dyslipidemia, hypertension, and diabetes.

Aim

To use path analysis to test the direct and indirect association, mediated by SMuRFs, between long-term cortisol levels measured in hair cortisol concentration (HCC) and CAD.

Methods

Hair was sampled from patients admitted with acute myocardial infarction (n = 203) and a population-based sample without a diagnosis or symptoms of CAD (n = 3,134). The HCC was analyzed using radioimmunoassay and all the participants reported whether they were diagnosed with or treated for diabetes, hypertension, and hyperlipidemia. Path analysis was used to test to what degree the association between logarithmized (ln) HCC and CAD was direct or indirect, mediated by SMuRFs.

Results

Participants with CAD had elevated HCC compared to those without elevated HCC [median interquartile range (IQR): 75.2 (167.1) vs. 23.6 (35.0) pg/mg, p < 0.0001]. Higher HCC was associated with diabetes, hypertension, and hyperlipidemia, which, in turn, were associated with CAD. In path models, 80% of the association between ln(HCC) and CAD were mediated by SMuRFs, while the direct path between ln(HCC) and CAD was not statistically significant.

Conclusion

The SMuRFs diabetes, hyperlipidemia, and hypertension mediate the association between ln(HCC) and CAD. Some association between ln(HCC) and CAD did not operate via the SMuRFs considered and might have a pathway through atherosclerosis or inflammation.

Determinants of Chronic Biological Stress, Measured as Hair Cortisol Concentration, in a General Population of Adolescents: From Individual and Household Characteristics to Neighborhood Urbanicity

Chronic biological stress may adversely affect adolescents' physical and mental health, but insight in the personal and environmental factors that determine chronic stress is limited. We measured 3-month cumulative hair cortisol concentration (HCC) in 419 adolescents, participating in the Flemish Environment and Health Study. Adolescents' health and lifestyle characteristics, household and neighborhood socio-economic status as well as neighborhood urbanicity were assessed as potential determinants of HCC, using multiple linear regression models. We additionally explored heterogeneity of our results by sex. HCC were significantly higher in boys from densely populated neighborhoods, the association was not significant in girls. Accordingly, boys living outside cities had significantly lower HCC than boys, living in cities. HCC was significantly lower in adolescents with an optimal vitality, a measure of a positive mental health status. In adolescent girls, menarcheal status (pre-/postmenarche) was a significant determinant of HCC. Our findings are the first to suggest that residential urbanicity may have an impact on chronic biological stress in a general population of adolescent boys.

Examining the Relationship Between Hair Cortisol With Stress-Related and Transdiagnostic Subclinical Measures

Background: Hair cortisol concentrations (HCC) provide a retrospective examination of long-term cortisol production as a measure of the hypothalamic-pituitary-adrenal (HPA) axis functioning, one of the major neural systems implicated in mediating the effects of stress on mental illness. However, evidence about the relationship between HCC with stressors and symptoms is scattered. In the present study, we aimed to examine the association between HCC and a wide range of stress-related and transdiagnostic subclinical measures in a sample of non-clinical young adults with a wide distribution of schizotypy. Methods: A total sample of 132 non-clinical young adults recruited at college and technical schools oversampled for schizotypy scores were assessed on distal and proximal stressful experiences, appraisals of stress, traits and symptoms of the affective, psychosis and dissociation spectrums, as well as stress-buffering measures, and provided 3 cm-hair samples. Results: No significant associations were found between HCC and any of the stress-related and subclinical measures. Only suspiciousness and disorganization showed a trend for a positive association with HCC but the magnitude was small. Conclusions: The present findings support previous studies indicating an overall lack of concordance between a broad range of stress-related and (sub)clinical phenotypic measures with hair cortisol. This study examined for the first time the relationship of HCC with the non-clinical expression of the psychosis spectrum, that is, schizotypy, which complements previous studies on clinical high risk and established psychosis and offers a promising strategy for studying possible HPA dysfunctions characterizing the subclinical psychosis continuum without the confounds associated to clinical psychosis.

CyberGenomics: Application of Behavioral Genetics in Cybersecurity

Cybersecurity (CS) is a contemporary field for research and applied study of a range of aspects from across multiple disciplines. A cybersecurity expert has an in-depth knowledge of technology but is often also recognized for the ability to view technology in a non-standard way. This paper explores how CS specialists are both a combination of professional computing-based skills and genetically encoded traits. Almost every human behavioral trait is a result of many genome variants in action altogether with environmental factors. The review focuses on contextualizing the behavior genetics aspects in the application of cybersecurity. It reconsiders methods that help to identify aspects of human behavior from the genetic information. And stress is an illustrative factor to start the discussion within the community on what methodology should be used in an ethical way to approach those questions. CS positions are considered stressful due to the complexity of the domain and the social impact it can have in cases of failure. An individual risk profile could be created combining known genome variants linked to a trait of particular behavior using a special biostatistical approach such as a polygenic score. These revised advancements bring challenging possibilities in the applications of human behavior genetics and CS.

Sociodemographics and chronic stress in mother-toddler dyads living in poverty

Experiencing chronic stress early in life is associated with later health disparities, and poverty may be a significant stressor for both mothers and children. With a sample of primarily Black and White mothers (N = 75) and toddlers (N = 71) living in poverty in the United States, we examined the direct relations between sociodemographic conditions of poverty and chronic physiological stress. Mothers completed questionnaires on sociodemographics, including mother/toddler race, mother's education, father's education, poverty level, economic hardship, marital status, unemployment status, and toddler sex. Physiological chronic stress was measured by assaying the cortisol content of 4 cm samples of hair cut from the posterior vertex of mothers and toddlers (20-24 months of age) to represent 4 months of stress. Mothers' and toddlers' chronic stress was significantly, moderately, and positively associated. Toddlers had a trending relationship of moderately higher chronic stress if they were Black compared to not Black. Mothers had significantly, moderately higher chronic stress if they were Black or had a Black toddler (compared to not Black), not married (compared to married), or were working (compared to not working). The findings suggest that these mothers, simultaneously navigating poverty and parenting a toddler, need resources to reduce chronic stress.

Hair cortisol concentrations among urban and rural-dwelling mother-child dyads, La Romana, Dominican Republic

Hair cortisol concentrations (HCC) were studied in mother-child dyads of La Romana, Dominican Republic (DR), a low-income city, and of the surrounding bateyes, sugarcane plantation villages with inhabitants frequently of Haitian descent. Populations of low socioeconomic status (SES) experience hypothalamic-pituitary-adrenal (HPA) axis dysregulation. Urban communities may be increasingly exposed to stressors such as crime and concentrated poverty whereas rural communities may be devoid of important community resources. As a result, the experience of stress in poverty may differ by place of residence. The goal of this study was to examine differences in HCC among urban and rural-dwelling mother-child dyads in socioeconomically disadvantaged communities surrounding La Romana, DR. Forty-five mother/child dyads were enrolled in La Romana and 45 at several bateyes surrounding La Romana. Mothers were ≥18 years and children were between 7 and 14 years. Mothers self-reported perceived stress and demographic factors. Hair samples were collected from mothers and children, and HCC was assessed using enzyme-linked immunosorbent assays. General linear models examined associations between socioeconomic factors and HCC, and between maternal and child HCC. HCC were measured in 88 maternal and 87 child samples (N = 175). Mothers living in a batey had higher HCC than those living in La Romana (p = 0.001). HCC was positively associated among maternal-child dyads (p = 0.001). Further, Haitian-born mothers as a population who frequently live in a rural batey experienced higher HCC (p = 0.025) that may partially be explained by discriminatory practices in the DR. This research helps to elucidate the impact of urban and rural environmental settings on HCC.Lay summaryThis study focuses on chronic stress, measured by hair cortisol levels, among a low-income population of Dominican and Haitian mother-child pairs who live in urban and rural settings. We found that Haitian-born mothers, who frequently live in a rural batey, had higher hair cortisol levels than Dominican born mothers. Hair cortisol levels between mothers and their children were positively associated. This study addresses the impact of urban and rural environments on the stress response among socioeconomically disadvantaged persons living in an upper middle income country who bear an excessive burden of psychosocial stress.

Stress and Learning in Pupils: Neuroscience Evidence and its Relevance for Teachers

Our understanding of how stress affects primary school children's attention and learning has developed rapidly. We know that children experience differing levels of stressors (factors that cause stress) in their environments, and that this can influence how they respond to new stressors when they occur in educational contexts. Here, we review evidence showing that stress can increase children's attention and learning capacities in some circumstances but hinder them in others. We show how children differ in their attention and learning styles, dependent on stress levels: for example, more highly stressed children may be more distracted by superficial features and may find it harder to engage in planning and voluntary control. We review intervention research on stress management techniques in children, concentrating on psychological techniques (such as mindfulness and stress reappraisal), physiological techniques (such as breathing exercises) and environmental factors (such as reducing noise). At the current time, raising teachers' awareness of pupils' differing stress responses will be an important step in accommodating the differing needs of children in their classrooms.

Associations between social adversity and young children's hair cortisol: A systematic review

Psychosocial and socioeconomic adversity in early childhood (termed 'social adversity') can have lifelong detrimental effects on health and development. Physiological stress is one proposed mechanism by which social adversity 'gets under the skin'. There is substantial research interest in whether hair cortisol, a biomarker proposed to measure the cumulative physiological stress response over time, can illustrate this mechanism. As a result, a growing number of studies have tested for associations between indicators of social adversity and child hair cortisol. The aim of this paper is to conduct a comprehensive, systematic review of the evidence for associations between indicators of social adversity and hair cortisol, specifically in young children (birth to 8 years) published any time up to 31 December 2019. The literature search identified 44 published studies that met inclusion criteria. The studies examined associations between one or more indicators of social adversity and child hair cortisol across 35 independent cohorts comprising 8370 children. Indicators of adversity examined in the identified literature included socioeconomic factors (e.g. low parental education, low income and unemployment), psychosocial factors (e.g. parent stress, poor mental health and family violence), and children's direct exposure to maltreatment, abuse and stressful events. Across all indicators of adversity, a total of 142 associations with hair cortisol were examined. Evidence of associations was limited and inconsistent; 34/142 (24%) showed evidence of a positive association between adversity and higher hair cortisol, 8/142 (6%) showed a negative association, and more than two thirds (100/142, 70%) of all examined associations were null. The collective evidence appears insufficient to conclude that there is a relationship between social adversity and hair cortisol, as a measure of physiological stress response, in young children.

Hair cortisol in mother-child dyads: examining the roles of maternal parenting and stress in the context of early childhood adversity

Physiological stress is thought to be one way that early adversity may impact children's health. How this occurs may be related to parental factors such as mothers' own stress and parenting behaviour. Hair cortisol offers a novel method for examining long-term physiological stress in mother-child dyads. The current study used hair cortisol to examine the role that maternal physiological stress and parenting behaviours play in explaining any effects of adversity on young children's physiological stress. This cross-sectional study comprised 603 mother-child dyads at child age 2 years, recruited during pregnancy for their experience of adversity through an Australian nurse home visiting trial. Hair cortisol data were available for 438 participating mothers (73%) and 319 (53%) children. Confirmatory factor analysis was used to define composite exposures of economic (e.g. unemployment, financial hardship) and psychosocial (e.g. poor mental health, family violence) adversity, and positive maternal parenting behaviour (e.g. warm, responsive). Structural equation modelling examined maternal mediating pathways through which adversity was associated with children's physiological stress. Results of the structural model showed that higher maternal and child physiological stress (hair cortisol) were positively associated with one another. Parenting behaviour was not associated with children's physiological stress. There was no evidence of any mediating pathways by which economic or psychosocial adversity were associated with children's physiological stress. The independent association identified between maternal and child hair cortisol suggests that young children's physiological stress may not be determined by exogenous environmental exposures; endogenous genetic factors may play a greater role.

Genetic parameters of hair cortisol as an indicator of chronic stress under different environments in Holstein cows

Chronic stress is a risk factor for a variety of physiological disorders because of its increased activation of the hypothalamic-pituitary-adrenal (HPA) axis; however, it is difficult to reveal environmental and genetic effects contributing to long-term HPA activity because of the complexity of chronic stress. The hair cortisol concentration (HCC) can be used to reflect the accumulation of HPA axis activity over time. Some studies suggest that the HCC might be associated with the protein concentration (PC) in the hair shaft; however, no studies have revealed a dynamic relationship between them. In the present study, 1,086 hair samples from 418 Holstein cows were collected, and the effects of environmental factors on HCC, PC, and ratio of HCC to PC (HCCP) were studied. Subsequently, regression analysis and curve fitting were used to identify for better-performing indicators of chronic stress. Additionally, univariate and bivariate genetic evaluation were used to estimate the genetic components of cortisol traits and genotype by environment interactions (G × E) under different environmental and physiological states. The results showed that HCC and PC are significantly affected by hair color, sampling year, and season, whereas HCCP is not influenced by hair color. Adjusted PC and HCCP, where confounding effects are excluded, were moderately related with chronic stress indicators. Moderate to high heritabilities were obtained for HCC (0.347 and 0.390 for winter and summer, respectively), PC (0.402 and 0.495 for winter and summer, respectively) and HCCP (0.289 and 0.460 for winter and summer, respectively) when animals in the same season were evaluated. A moderate G × E interaction was detected in this study, as indicated by the low or negative genetic correlation for the same cortisol trait in different environments (e.g. heat stress condition and thermoneutral condition). In conclusion, HCCP is not affected by hair color compared with the other 2 traits; thus, it has potential as an indicator of chronic stress. Hair cortisol traits could monitor stress response process in cattle, as well as provide a better understanding of genetic mechanism for long-term HPA activity.

Hair Cortisol Concentration, Weight Loss Maintenance and Body Weight Variability: A Prospective Study Based on Data From the European NoHoW Trial

Several cross-sectional studies have shown hair cortisol concentration to be associated with adiposity, but the relationship between hair cortisol concentration and longitudinal changes in measures of adiposity are largely unknown. We included 786 adults from the NoHoW trial, who had achieved a successful weight loss of ≥5% and had a body mass index of ≥25 kg/m² prior to losing weight. Hair cortisol concentration (pg/mg hair) was measured at baseline and after 12 months. Body weight and body fat percentage were measured at baseline, 6-month, 12-month and 18-month visits. Participants weighed themselves at home ≥2 weekly using a Wi-Fi scale for the 18-month study duration, from which body weight variability was estimated using linear and non-linear approaches. Regression models were conducted to examine log hair cortisol concentration and change in log hair cortisol concentration as predictors of changes in body weight, change in body fat percentage and body weight variability. After adjustment for lifestyle and demographic factors, no associations between baseline log hair cortisol concentration and outcome measures were observed. Similar results were seen when analysing the association between 12-month concurrent development in log hair cortisol concentration and outcomes. However, an initial 12-month increase in log hair cortisol concentration was associated with a higher subsequent body weight variability between month 12 and 18, based on deviations from a nonlinear trend (β: 0.02% per unit increase in log hair cortisol concentration [95% CI: 0.00, 0.04]; P=0.016). Our data suggest that an association between hair cortisol concentration and subsequent change in body weight or body fat percentage is absent or marginal, but that an increase in hair cortisol concentration during a 12-month weight loss maintenance effort may predict a slightly higher subsequent 6-months body weight variability.

CLINICAL TRIAL REGISTRATION

ISRCTN registry, identifier ISRCTN88405328.

Familial associations in hair cortisol concentration: A cross-sectional analysis based on the Healthy Start study

A few studies have shown a direct association between maternal and child hair cortisol concentrations (HCC), but the potential correlations within paternal-child and maternal-paternal dyads are not clear from the current evidence. Thus, we aimed to thoroughly examine associations between family members HCC. We conducted a cross-sectional study based on 159 children and their parents (159 mothers and 159 fathers) participating in the Danish Healthy Start Study. Information was available on HCC from both children, mothers and fathers, as well as on several sociodemographic factors. First, Pearson's correlation coefficients were applied to assess crude correlations between family members' HCC. Secondly, analysis of covariance, adjusted for covariates, was applied to estimate child mean HCC in quartiles of maternal and paternal HCC, and mean paternal HCC in quartiles of maternal HCC. Our results showed direct associations between HCC of all family members. We found statistically robust correlations between maternal and child HCC (r = 0.33; P < 0.001), paternal and child HCC (r = 0.37; P < 0.001) and between maternal and paternal HCC (r = 0.31; P < 0.001). Similar results were found when adjusting for covariates in analyses of covariance. Our data provides evidence of associations between family members' HCC. However, we were unable to determine the extent to which these associations were due to shared genetics, assortative mating or environmental factors.

Hair sampling for cortisol analysis with mother-toddler dyads living in low-income homes

BACKGROUND

A first step to advance stress science research in young children is understanding the relationship between chronic stress in a mother and chronic stress in her child. One non-invasive measure of chronic stress is hair cortisol. However, little is known about strategies for hair sampling in mother-toddler dyads living in low-income homes in the U.S. To address prior limitations, the purpose of this study was to understand the feasibility of sampling hair for cortisol analysis in mother-toddler dyads living in low-income homes in the U.S. We examined feasibility related to participation, eligibility, and gathering an adequate hair sample weight.

METHODS

We approached 142 low-income, racially diverse, urban-dwelling mothers who were participating in an ongoing longitudinal birth cohort study for informed consent to cut approximately 150 hairs from the posterior vertex of their scalp and their toddlers' (20-24 months) scalp. We demonstrated the process of sampling hair with a hairstyling doll during home visits to the mother and toddler using rounded-end thinning shears.

RESULTS

Overall, 94 of 142 mother-toddler dyads (66 %) participated in hair sampling. The most common reason for participation refusal was related to hairstyle. All but three hair samples were of adequate weight for cortisol extraction.

DISCUSSION

The findings from this study can help researchers address sampling feasibility concerns in hair for cortisol analysis research in mother-toddler dyads living in low-income homes in the U.S.

Longitudinal effects of family psychopathology and stress on pubertal maturation and hormone coupling in adolescent twins

Adolescents experience profound neuroendocrine changes, including hormone "coupling" between cortisol, testosterone, and dehydroepiandrosterone. Emerging research has only begun to elucidate the role of hormone coupling, its genetic and environmental etiology, and the extent to which coupling is impacted by gender, puberty, and family context. We included measures on parent and child mental health, parenting stress, and family conflict of 444 twin pairs and their parents across two timepoints, when youth were on average 8 and 13 years old, respectively. Structural equation models examined the impact of family context effects on coupling during adolescence. Biometric twin models were then used to probe additive genetic, shared, and non-shared environmental effects on hormone coupling. Hormones were more tightly coupled for females than males, and coupling was sensitive to parental depression and co-twin psychopathology symptoms and stress exposure in females. The association between family context and coupling varied across specific neuroendocrine measures and was largely distinct from pubertal maturation. Biometric models revealed robust shared and non-shared environmental influences on coupling. We found that family antecedents modify the strength of coupling. Environmental influences account for much of the variation on coupling during puberty. Gender differences were found in genetic influences on coupling.

Investigating individual stress reactivity: High hair cortisol predicts lower acute stress responses

Identifying individual differences in stress reactivity is of particular interest in the context of stress-related disorders and resilience. Previous studies already identified several factors mediating the individual stress response of the hypothalamus-pituitary-adrenal axis (HPA). However, the impact of long-term HPA axis activity on acute stress reactivity remains inconclusive. To investigate associations between long-term HPA axis variation and individual acute stress reactivity, we tested 40 healthy volunteers for affective, endocrine, physiological, and neural reactions to a modified, compact version of the established in-MR stress paradigm ScanSTRESS (ScanSTRESS-C). Hair cortisol concentrations (HCC) served as an integrative marker of long-term HPA axis activity. First, the ScanSTRESS-C version proved to be valid in evoking a subjective, endocrine, physiological, and neural stress response with enhanced self-reported negative affect and cortisol levels, increased heart rate as well as increased activation in the anterior insula and the dorso-anterior cingulate cortex (dACC). Second and interestingly, results indicated a lower neuroendocrine stress response in individuals with higher HCC: HCC was negatively correlated with the area under the curve (respect to increase; AUCi) of saliva cortisol and with a stress-related increase in dACC activity. The present study explicitly targeted the relationship between HCC and acute stress reactivity on multiple response levels, i.e. subjective, endocrine and neural stress responses. The lower stress reactivity in individuals with higher HCC levels indicates the need for further research evaluating the role of long-term HPA axis alterations in the context of vulnerability or immunization against acute stress and following stress-related impairments.

Prenatal maternal stress and child hair cortisol four years later: Evidence from a low-income sample

BACKGROUND

Maternal stress during pregnancy can influence the trajectory of fetal development, shaping offspring physiology and health in enduring ways. Some research implicates fetal programming of the hypothalamic-pituitary-adrenocortical (HPA) axis as a mediator of these effects. The present study is the first to examine child hair cortisol concentration (HCC) and maternal stress during pregnancy in a diverse, low-income sample.

METHODS

The sample consisted of 77 healthy, low-income (M annual income: $13,321), mother-children pairs (M child age = 3.81 years, SD = 0.43). The children were 57 % girls, 43 % boys. Mothers were 65 % Latina/Hispanic, 28 % Non-Hispanic White, 7% Black/African American. Maternal prenatal stress was measured with the Perceived Stress Scale administered by interview in the second and third trimesters, and again approximately four years later when child hair samples for assaying HCC were collected.

RESULTS

On average maternal perceived stress increased significantly across pregnancy, then returned to lower levels 4 years after birth. Regression analysis revealed that child HCC was not significantly predicted by maternal perceived stress at either single prenatal time point. Exploratory analysis revealed evidence of a relation between increases in maternal prenatal stress from second to third trimester and child HCC four years later (r = .37, p =  .04).

CONCLUSIONS

These results suggest that measures of prenatal maternal stress at any one time point may not be predictive of offspring long-term HPA output in low-income child samples, but that increases in stress levels across pregnancy may provide important information undetected by individual time point measures.

Hair cortisol concentration mediates the association between parent and child psychopathology

Parent and child mental health are strongly associated and this association may be transmitted via disruption to the hypothalamic-pituitary-adrenal axis in children. This study examined the potential mediating role of hair cortisol concentration (HCC) in the association between parent psychopathology and child mental disorder. Data come from 100 children diagnosed with a mental disorder [major depression (66 %), generalized anxiety (58 %), attention-deficit hyperactivity (33 %), oppositional defiant (35 %)] and their parents. Parent psychopathology was measured using the Center for Epidemiological Studies Depression Scale and State-Trait Anxiety Inventory. Child mental disorder was measured using the Mini International Neuropsychiatric Interview and hair samples were assayed using high-sensitivity ELISA for cortisol extraction. Sex-specific path models were specified to estimate mediating effects (αβ). Children were, on average, 14.4 (SD 2.3) years of age and 70 % were girls. Adjusting for child age, parent sex, and family income, HCC mediated the association between symptoms of parent psychopathology and major depression and attention-deficit hyperactivity in all children (αβ ranging -0.07 to 0.19; 38-46 % effect mediated). Mediating effects for generalized anxiety and opposition defiant were evident for boys only (αβ ranging -0.26 to 0.14; 31-38 % effect mediated). Evidence suggests HCC partially mediates the association between parent psychopathology and child mental disorder, and for generalized anxiety and oppositional defiant, this effect is specific to boys. Family inventions to reduce child stress may be effective in buffering the consequences of parent psychopathology. Further research that considers sex effects is needed to clarify how HCC conditions risk for mental disorder in children.

Long-Term Stability of Cortisol Production and Metabolism Throughout Adolescence: Longitudinal Twin Study

Life-course experiences have been postulated to program hypothalamus-pituitary-adrenal (HPA) axis activity, suggesting that HPA axis activity is, at least partially, stable over time. Yet, there is paucity of data on the long-term stability of cortisol production and metabolism. We performed a prospective follow-up study in twins recruited from a nationwide register to estimate the stability of cortisol production and metabolism over time, and the contribution of genetic and environmental factors to this stability. In total, 218 healthy mono- and dizygotic twins were included. At the ages of 9, 12 and 17 years, morning urine samples were collected for assessment (by gas chromatography-tandem mass spectrometry) of cortisol metabolites, enabling the calculation of cortisol metabolite excretion rate and cortisol metabolism activity. Our results showed a low stability for both cortisol metabolite excretion rate (with correlations <.20) and cortisol metabolism activity indices (with correlations of .25 to .46 between 9 and 12 years, -.02 to .15 between 12 and 17 years and .09 to .28 between 9 and 17 years). Because of the low stability over time, genetic and environmental contributions to this stability were difficult to assess, although it seemed to be mostly determined by genetic factors. The low stability in both cortisol production and metabolism between ages 9 and 17 years reflects the dynamic nature of the HPA axis.

Pituitary dysmaturation affects psychopathology and neurodevelopment in 22q11.2 Deletion Syndrome

BACKGROUND

22q11.2 Deletion Syndrome (22q11DS) confers strongly increased genetic risk for multiple psychiatric disorders. Similarly to the general population, rates of psychiatric comorbidity suggest that common disease mechanisms are shared across dimensions of psychopathology. Such pleiotropic disease mechanisms remain however currently unknown. We hypothesized that pituitary dysmaturation, indicative of HPA-axis dysregulation, could correlate to reduced tolerance to daily life stressors and reflect pleiotropic risk factor for psychopathology. Moreover HPA-axis dysregulation could affect atypical cortical and hippocampal development previously described in 22q11DS.

METHODS

Pituitary volume, hippocampal volume and cortical thickness measures were obtained from T1-weighted MRI images in a large longitudinal cohort of youth with 22q11DS (115 subjects, 260 scans, age-range = 5.4-31.6) and healthy controls (151 subjects, 280 scans, age-range = 5.1-32.3). We explored effects of pituitary dysmaturation on tolerance to stress, psychopathology and neurodevelopment employing mixed-models linear regression. Associations of pituitary and cortical development were correlated with the expression pattern of glucocorticoid receptor gene NR3C1 obtained from the Allen-Human-Brain-Atlas.

RESULTS

We observed aberrant pituitary developmental trajectories in 22q11DS, with volumetric reductions emerging by young-adulthood (P = 0.0006). Longitudinal pituitary decline was associated with to reduced tolerance to stress (P = 0.04), higher overall psychopathology (P = 0.0003) and increased risk of psychiatric comorbidity (P = 0.02). Moreover, pituitary decline correlated with blunted growth of the right hippocampus (P = 0.03) and to increased cortical thinning of mostly temporal and orbitofrontal regions mediated by NR3C1 gene expression.

CONCLUSION

Atypical pituitary development could reflect progressive extinction of HPAA due to chronic hyper-activation, in agreement with existing biochemical evidence in 22q11DS. HPAA dysregulation could represent and endophenotype that confers pleiotropic vulnerability to psychopathology and atypical neurodevelopment in 22q11DS.

Heritability of Cortisol Production and Metabolism Throughout Adolescence

CONTEXT

Inter-individual differences in cortisol production and metabolism emerge with age and may be explained by genetic factors.

OBJECTIVE

To estimate the relative contributions of genetic and environmental factors to inter-individual differences in cortisol production and metabolism throughout adolescence.

DESIGN

Prospective follow-up study of twins.

SETTING

Nationwide register.

PARTICIPANTS

218 mono- and dizygotic twins (N = 109 pairs) born between 1995 amd 1996, recruited from the Netherlands Twin Register. Cortisol metabolites were determined in 213, 169, and 160 urine samples at the ages of 9, 12, and 17, respectively.

MAIN OUTCOME MEASURES

The total contribution of genetic factors (broad-sense heritability) and shared and unshared environmental influences to inter-individual differences in cortisol production and activities of 5α-reductase, 5β-reductase, and 11β-hydroxysteroid dehydrogenases and cytochrome P450 3A4.

RESULTS

For cortisol production rate at the ages of 9, 12, and 17, broad-sense heritability was estimated as 42%, 30%, and 0%, respectively, and the remainder of the variance was explained by unshared environmental factors. For cortisol metabolism indices, the following heritability was observed: for the A-ring reductases (5α-and 5β-reductases), broad-sense heritability increased with age (to >50%), while for the other indices (renal 11β-HSD2, global 11β-HSD, and CYP3A4), the contribution of genetic factors was highest (68%, 18%, and 67%, respectively) at age 12.

CONCLUSIONS

The contribution of genetic factors to inter-individual differences in cortisol production decreased between 12 and 17y, indicative of a predominant role of individual circumstances. For cortisol metabolism, distinct patterns of genetic and environmental influences were observed, with heritability that either increased with age or peaked at age 12y.

Hair cortisol, perceived stress, and social support in mother-child dyads living in an urban neighborhood

Women and children belonging to a racial/ethnic minority bear a disproportionate burden of psychosocial stress that increases their vulnerability to adverse health outcomes. Hair cortisol has been rapidly advanced as a biomarker of the intensity and course of the stress response over time and may provide an opportunity to increase our understanding of the role of psychological stress in health. However, research on the link between hair cortisol levels and subjective measures of maternal and child stress among low-income and minority individuals is limited. The goal of this study was to examine the association between stress and hair cortisol in low income, minority women and children who experience disproportionate exposure to chronic stress. A convenience sample of 54 minority mother/child dyads from a busy primary care clinic in the second poorest medium-sized city in the US participated in the study. Mothers self-reported perceived stress, social support, household characteristics and other demographic factors, and their children (ages 7-14 years) reported on the perceived level of safety in their neighborhood and exposure to violence as markers of child stress. Three-centimeter hair samples were collected from both mothers and children during the clinic visit, and hair cortisol levels were assessed via enzyme-linked immunosorbent assays. Linear regression models examined associations between maternal and child hair cortisol, and between hair cortisol and perceived stress level in women, and moderation by social support. Maternal hair cortisol was not significantly associated with mother's perceived stress. Maternal and child hair cortisol levels were positively associated (p = .007) but this association was not moderated by maternal perceived social support. These findings suggest that hair cortisol is strongly associated among this sample of minority mother-child dyads and is not moderated by social support.

Co-twin relationship quality as a moderator of genetic and environmental factors on urinary cortisol levels among adult twins

Previous research has indicated that genetic and environmental factors shape physiological activity. Cortisol levels, in particular, have received significant attention, with studies indicating substantive heritability estimates across various sampling techniques. A related line of research has indicated that genetic and environmental factors that explain variability in cortisol levels may vary across context and experiences by way of gene-environment interactions (G × Es). Despite these findings, a limited number of studies have examined the extent to which interpersonal relationships may operate as a moderator. The current study focused on co-twin relationship quality as a source of moderation, as twins are more likely to have contact with one another and to form close, interpersonal relationships with their co-twin relative to singleton siblings. Using a sample of 298 adult twins from the National Survey of Midlife Development in the United States (MIDUS), we examined the extent to which genetic and environmental factors that explain variability in urinary cortisol levels varied across levels of co-twin relationship quality. The heritability of cortisol levels was greater and nonshared environmental influences were lower at greater levels of relationship quality. These findings suggest that the heritability of cortisol may vary across context, and positive relationships with others may moderate such factors.

HPA axis responses to psychological challenge linking stress and disease: What do we know on sources of intra- and interindividual variability?

Stress is an ubiquitous phenomenon with significant impact on human physiology when it lasts too long, when it is too intense, or when it hits vulnerable individuals. Examining the mechanisms linking stress exposure with health and disease is an important endeavor in psychoneuroendocrine research. Empirical evidence so far revealed large intra- as well as inter-individual variability in hypothalamic-pituitary-adrenal (HPA) axis responses to acute psychosocial stress, showing that the HPA axis is a highly adaptive system. Thus, the characterization of intra- und inter-individual patterns of HPA axis reactivity is of high scientific interest and forms the basis on which mechanistic links between stress response (dys)regulation and health impairments can be examined. To date, basic knowledge has been, and still is, accumulated on demographic, biological (including genetic and epigenetic) factors, lifestyle behavioral variables, consumption of substances and medication, psychological and personality factors, as well as on methodological aspects. Besides this, there is also very recent progress in respect to the development of laboratory stress paradigms that can be applied in virtual reality or inside an MRI-scanner. In sum, the present review updates our current knowledge on moderating and intervening factors as sources of intra- und inter-individual variability in human cortisol stress responses and offers recommendations for future research designs.

Effects of 5-HTTLPR genotype and cognitive rumination on long-term cortisol reactivity measured in human hair

Ample experimental and associative studies have shown that carrying two short (S) alleles of the serotonin transporter gene (5-HTTLPR) contributes to an increased vulnerability for stress and related affective disorders. Recent findings indicate that this relationship might become even more profound when also possessing a negative ruminative (stress-related) thinking style. However, previous studies on the relationship among 5-HTTLPR, stress, and stress-responsiveness almost exclusively measured salivary cortisol concentrations during exposure to a single acute (laboratory) stressor. Measuring cortisol concentrations over longer periods of time might better reflect (chronic) Gene by biological (HPA) stress responsiveness associations. In recent years, the strategy to assess hair cortisol concentration (HCC) has been established as a more reliable marker for chronic HPA activations. The current study explored associations between 3-months accumulated HCC and the tendency to ruminate about negative events in 27 S/S and 27 L/L 5-HTTLPR-carriers (screened from a large n = 827 DNA database). Hierarchical regression (including moderation) analyses revealed clear significant interactions between Genotype and Rumination (p < 0.01, f²=0.26); indicating greatest accumulation of HCC in high ruminating S/S-allele carriers. These findings implicate that the combined possession of a genetic (S-allele 5-HTTLPR) and cognitive (Rumination) stress-vulnerability might meaningfully increases long-term stress responsiveness; most likely due to increased daily (chronic) stress experiences. Lay summary   The current study investigated whether the combined possession of a biological (genetic) and cognitive (negative thinking pattern) stress vulnerability may lead to a greater vulnerability to experience daily stress. This hypothesis was confirmed as a higher accumulation of the cortisol stress hormone was found over the past 3 months in scalp hair of participants that carried both vulnerability factors in combination.

Hair cortisol in newly diagnosed bipolar disorder and unaffected first-degree relatives

OBJECTIVE

Hair cortisol is a promising new biomarker of retrospective systemic cortisol concentration. In this study, we compared hair cortisol concentrations in patients with newly diagnosed bipolar disorder (BD), their unaffected first-degree relatives and healthy individuals and identified potential predictors of hair cortisol concentrations in patients with BD.

METHOD

In a cross-sectional design, we compared hair cortisol concentrations in 181 patients with newly diagnosed/first episode BD, 42 of their unaffected first-degree relatives and 101 healthy age- and sex-matched individuals with no personal or first-degree family history of affective disorder. In patients with BD, we further investigated whether medication- and illness related variables, as well as measures of stressful life events in the preceding 12 months and childhood trauma, were associated with hair cortisol concentrations.

RESULTS

Hair cortisol concentrations were 35.1% (95%CI: 13.0-61.5) higher in patients with BD (P = 0.001) compared with healthy individuals in models adjusted for age and sex. Hair cortisol concentrations in unaffected first-degree relatives did not differ from healthy individuals (P = 0.8). In patients, neither medication, illness duration nor stress related variables were associated with hair cortisol concentrations.

CONCLUSION

We found elevated hair cortisol concentrations in patients newly diagnosed with BD indicating the presence of physiological stress in early stages of BD.

Genome-wide interaction study of a proxy for stress-sensitivity and its prediction of major depressive disorder

Individual response to stress is correlated with neuroticism and is an important predictor of both neuroticism and the onset of major depressive disorder (MDD). Identification of the genetics underpinning individual differences in response to negative events (stress-sensitivity) may improve our understanding of the molecular pathways involved, and its association with stress-related illnesses. We sought to generate a proxy for stress-sensitivity through modelling the interaction between SNP allele and MDD status on neuroticism score in order to identify genetic variants that contribute to the higher neuroticism seen in individuals with a lifetime diagnosis of depression compared to unaffected individuals. Meta-analysis of genome-wide interaction studies (GWIS) in UK Biobank (N = 23,092) and Generation Scotland: Scottish Family Health Study (N = 7,155) identified no genome-wide significance SNP interactions. However, gene-based tests identified a genome-wide significant gene, ZNF366, a negative regulator of glucocorticoid receptor function implicated in alcohol dependence (p = 1.48x10-7; Bonferroni-corrected significance threshold p < 2.79x10-6). Using summary statistics from the stress-sensitivity term of the GWIS, SNP heritability for stress-sensitivity was estimated at 5.0%. In models fitting polygenic risk scores of both MDD and neuroticism derived from independent GWAS, we show that polygenic risk scores derived from the UK Biobank stress-sensitivity GWIS significantly improved the prediction of MDD in Generation Scotland. This study may improve interpretation of larger genome-wide association studies of MDD and other stress-related illnesses, and the understanding of the etiological mechanisms underpinning stress-sensitivity.

Hair cortisol concentration in mothers and their children: roles of maternal sensitivity and child symptoms of attention-deficit/hyperactivity disorder

Associations between mothers' and children's cortisol secretion parameters are well established. According to the bio-behavioral synchrony model, these associations reflect influences of the mother-child relationship, the child's social adjustment, and might also reflect shared genetic dispositions. From the bio-behavioral synchrony model, we predicted a stronger mother-child hair cortisol concentration (HCC) link in mothers showing highly adequate (compared to those showing less adequate) parenting behaviors and in children showing low (compared to those showing high) ADHD symptoms. From a genetic perspective, no such moderator effects, or a stronger mother-child HCC link in children with high ADHD symptoms, can be expected. The study sample consisted of 111 4-5-year-old children (64 of whom screened positive for increased ADHD symptoms) and their mothers. ADHD symptoms were assessed by a clinical interview and parent and teacher questionnaires. Maternal sensitive/responsive parenting behavior was assessed by an at-home behavior observation procedure. In mothers and children, HCC in the most proximal 3-cm scalp hair segment was analyzed using luminescence immunoassay. Overall HCCs of mothers and their children correlated significantly. Maternal sensitivity/responsiveness and child ADHD symptoms proved to be significant moderator variables of this association: High maternal sensitivity/responsiveness and low ADHD symptoms of the child were associated with a stronger mother-child link in HCC. The findings are in line with the bio-behavioral synchrony model in the mother-child relationship, and are less compatible with a genetic perspective. The results might hint at environmental events influencing the development of stress axis functioning in subgroups of preschoolers with high ADHD symptoms.

Hair cortisol analysis: An update on methodological considerations and clinical applications

BACKGROUND

Hair cortisol analysis is increasingly being appreciated and applied in both research and medicine, aiding endocrinologists with diagnosis.

CONTENT

We provide an overview of hair cortisol research in general and an update on methodological considerations including the incorporation of cortisol into hair, hair growth rates, and sampling procedures, mincing vs. grinding of samples during preparation for extraction, various extraction protocols, and quantification techniques. We compare the clinical utility and application of hair cortisol with traditional methods of measurement while acknowledging the limitations of analysis including variations in hair growth parameters. We explore the value of hair cortisol in cases of Cushing syndrome (particularly Cyclical Cushing), Adrenal insufficiency (including Addison's disease), therapy monitoring, cardiovascular disease, stress, and mental illness.

SUMMARY

Hair cortisol provides a unique objective biomarker for the analysis of endogenous cortisol levels for not only clinical diagnostic purposes but also in research. The use of hair cortisol has great potential for advancing patient care.