Higher Hair Cortisol Concentrations Research Articles

Mothers in stress: Hair cortisol of mothers living in marginalised Roma communities and the role of socioeconomic disadvantage

Roma living in marginalised communities are among the most disadvantaged groups in Slovakia. Socioeconomic disadvantage is associated with higher hair cortisol concentrations (HCC), including in parents. The aim of this study is therefore to assess differences in HCC, reflecting the levels of stress, between mothers living in MRCs and from the majority population, to assess the association of socioeconomic disadvantage with HCC, and whether disadvantage mediates the MRC/majority differences in HCC. Participants were mothers of children aged 15–18 months old living in MRCs (N=61) and from the Slovak majority population (N=90). During preventive paediatric visits, visits at community centres and home visits, hair samples and data by questionnaire were collected. HCC differed significantly between mothers living in MRCs and mothers from the majority population, with the mean HCC value being twice as high in mothers living in MRCs (22.98 (95% confidence interval, CI, 15.70–30.30) vs. 11.76 (8.34–15.20), p<0.05). HCC was significantly associated with education, household equipment and household overcrowding, but not with billing, socioeconomic stress and social support. The difference in HCC between mothers living in MRCs and mothers from the majority population was partially mediated by poor house equipment, such as no access to running water, no flushing toilet or no bathroom (the indirect effect of B=7.63 (95% CI: 2.12–13.92)). Practitioners and policymakers should be aware of high stress levels among mothers living in MRCs and aim at enhancing their living and housing conditions.

Cumulative environmental stress and emerging cardiometabolic risk during childhood.

To prospectively evaluate the relationship between cumulative environmental stress and cardiometabolic risk in middle childhood, and to examine whether hair cortisol, a measure of hypothalamic pituitary adrenal-axis activity, mediates this relationship. In a cohort of children from low-income households (n = 320; 59% Hispanic, 23% Black, body mass index (BMI) percentile >50th at enrollment), environmental stressors including family and neighbourhood factors representing disadvantage/deprivation, and cortisol concentrations from hair samples, were measured over five timepoints beginning when children were 2-4 years old. Cardiometabolic risk factors (i.e., BMI, blood pressure, lipids, blood sugar, C-reactive protein) were measured at the final timepoint when children were 7-11 years of age. In adjusted logistic regression models, greater cumulative environmental stress was associated with a higher likelihood of elevated cardiometabolic risk in middle childhood (p = 0.01). Children from minoritized racial/ethnic groups had a higher prevalence of both stressors and cardiometabolic risk factors. Cumulative environmental stress was associated with higher hair cortisol concentrations (p < 0.01). However, hair cortisol was not directly associated with cardiometabolic risk factors and did not explain the association between environmental stress and cardiometabolic risk in causal mediation analysis. The influence of cumulative stress on cardiometabolic health can be observed in middle childhood and may contribute to cardiometabolic health disparities, highlighting the importance of public health interventions to mitigate disadvantage.

Prenatal stress and hair cortisol in a sample of Latina women

BackgroundStress during pregnancy adversely impacts maternal and infant health. Dysregulation of the hypothalamic pituitary axis is a mediator of the relationship between stress and health. Evidence supporting an association between prenatal chronic stress and cortisol is limited, and the majority of research published has been conducted amongst White participants, who experience less chronic stress than people of color. AimThis study investigated associations between various measures of prenatal stress and hair cortisol concentrations which is a biomarker of the integrated stress response in a sample of Latina participants during the third trimester of pregnancy. MethodPregnant women (n=45) were surveyed with scales measuring chronic stress, perceived stress, pregnancy-related and pregnancy-specific anxiety. Hair samples were collected as an objective neuroendocrine measure of chronic stress. Linear regression analyses were performed to assess associations between stress measures and hair cortisol. Pre-pregnancy BMI, smoking during pregnancy, and steroid use during pregnancy were used as covariates in adjusted models. ResultsChronic stress, operationalized as maternal reports of neighborhood/housing strain, daily activities and relationship strain, discrimination, and financial strain, was significantly associated with higher hair cortisol concentrations. No significant associations were found between hair cortisol and perceived stress, pregnancy-related anxiety, nor pregnancy-specific anxiety in adjusted models. ConclusionChronic stress may be a more robust correlate of physiological stress, as measured by hair cortisol in pregnancy, than other common measures of prenatal stress and anxiety.

Cortisol levels across the lifespan in common marmosets (Callithrix jacchus).

Human aging is associated with senescence of the hypothalamic-pituitary-adrenal (HPA) axis, leading to progressive dysregulation characterized by increased cortisol exposure. This key hormone is implicated in the pathogenesis of many age-related diseases. Common marmosets (Callithrix jacchus) display a wide spectrum of naturally occurring age-related pathologies that compare similarly to humans and are increasingly used as translational models of aging and age-related disease. Whether the marmoset HPA axis also shows senescence with increasing age is unknown. We analyzed hair cortisol concentration (HCC) across the lifespan of 50 captive common marmosets, ranging in age from approximately 2 months-14.5 years, via a cross-sectional design. Samples were processed and analyzed for cortisol using enzyme immunoassay. HCC ranged from 1416 to 15,343 pg/mg and was negatively correlated with age. We found significant main effects of age group (infant, adolescent, adult, aged, very aged) and sex on HCC, and no interaction effects. Infants had significantly higher levels of HCC compared with all other age groups. Females had higher HCC than males. There was no interaction between age and sex. These results suggest marmosets do not show dysregulation of the HPA axis with increasing age, as measured via HCC.

A two-component model of hair cortisol concentration in fibromyalgia: Independent effects of pain chronicity and severity.

Fibromyalgia (FM) is a chronic pain disorder of unknown aetiopathogenesis, in which the role of activity of the hypothalamic-pituitary-adrenal (HPA) axis is not clearly established. This study analysed the modulatory effects of disease chronicity and severity on cortisol levels. Hair cortisol concentrations (HCC) and clinical evaluation data (pain severity, impact of FM on daily activities, depression, anxiety, fatigue and insomnia) were collected from 47 female patients with FM and 36 healthy women (HW). The results showed that disease chronicity, with a negative effect, and symptom severity, with a positive effect, were independent predictors of HCC. Patients with a shorter disease duration had higher HCC than patients with a longer disease duration and healthy participants. Furthermore, patients with greater symptom severity had higher HCC than those patients with lower clinical severity and healthy participants. While disease chronicity in FM was associated with a decrease in HCC, clinical severity increased HCC. These results support the existence of a dysfunction in the regulation of the HPA axis in FM and its possible contribution to chronic pain development. This is the first study to assess hair cortisol concentrations in a specific sample of patients with fibromyalgia (FM). This method is especially useful for the assessment of long-term regular cortisol excretion. Results showed a two-component model for explaining cortisol levels: disease chronicity, with a negative effect, and symptom severity, with a positive effect. This suggests that severe pain/stress evokes higher cortisol levels at earlier stages of FM, while in the longer term a decrease in cortisol levels was observed.

Relationship between hair cortisol concentrations and cognitive functioning in adolescents with ADHD

ABSTRACT Background: Our study aimed to explore whether the hair cortisol concentration (HCC), a measure of long-term cortisol output, is associated with poorer cognitive functioning in adolescents with attention deficit and hyperactivity disorder (ADHD). We further aimed to test the potential moderating effects of sex and childhood maltreatment. Methods: In this cross-sectional study, fifty-three adolescents with ADHD were studied. The ADHD Rating Scale (ADHD-RS) and Childhood Trauma Questionnaire (CTQ) were administered. Seven cognitive tasks from the Cambridge Neuropsychological Test Automated Battery (CANTAB) were administered, and two cognitive factors (attention and memory and executive functioning) were identified by confirmatory factor analysis. A 3-cm hair sample from the posterior vertex region of the head was obtained. HCCs were determined by a high-sensitivity enzyme immunoassay kit. Multiple linear regression analyses were used to explore the association between HCCs and either cognitive performance or ADHD severity while adjusting for sex, childhood maltreatment and the ADHD-RS total score. Results: Sex moderated the relationship between HCCs and attention/memory confirmatory factor analysis (CFA) scores, with better performance in boys with higher HCCs. HCCs were not associated with executive functioning or ADHD symptoms. Childhood maltreatment was associated with inattention symptoms in adolescents with ADHD. Conclusions: Our study suggests that HCCs are positively associated with attention and memory performance in adolescents with ADHD, with a moderating effect of sex (the relationship is strongest in boys).

The role of stress and health behaviour in linking weight discrimination and health: a secondary data analysis in England

ObjectiveTo examine the role of stress and health-risk behaviours in relationships between weight discrimination and health and well-being.DesignSecondary data analysis of an observational cohort study.SettingThe English Longitudinal Study of Ageing.ParticipantsData...

Excessive hair cortisol concentration as an indicator of psychological disorders in children

Cortisol in hair is a new biomarker assessing long-term hypothalamic-pituitary-adrenal (HPA) axis activity, which is related to emotion regulation. We compare hair cortisol concentrations (HCC), in clinically referred children with disruptive mood dysregulation disorder (DMDD) (n = 19), children with other types of psychological disorders (n = 48), and healthy subjects (n = 36). We also investigate the association between HCC and irritability, age, and sex. Our results show that children with DMDD or other types of psychological disorders have higher HCC than healthy subjects, p < .001, ηp2 = .39. No difference between children with DMDD and those with other types of psychological disorders was found, p = .91, nor an association between HCC and irritability in the clinical sample, p = .32. We found a significant negative correlation between HCC and age in those with DMDD, r = −0.54, p < .05, but not in the normative sample, r = −0.20, p = .25. No differences in HCC between girls and boys were found in the normative sample, p = .49. Children in need of psychological treatment, including those with DMDD, seem to have dysregulated HPA-axis activity over time. Excessive accumulated cortisol concentrations in hair could be an indicator of a psychological disorder in children.

Hair Cortisol Concentrations in Feral Horses and the Influence of Physiological and Social Factors

Cortisol is a glucocorticoid hormone produced during activation of the hypothalamic–pituitary–adrenal axis (HPA) in response to psychological or physiological demands. High amounts of circulating cortisol can be found in individuals experiencing energetically demanding physiological events, such as pregnancy, lactation, injury, or starvation, but, also, in individuals who may have less obvious HPA activation from social situations. The feral horse population on Sable Island (Nova Scotia, Canada) provides an opportunity to look at hair cortisol concentration (HCC) as a proxy for circulating cortisol concentration to better understand physiological correlates. The horse’s complex social structure also allows us to look at how the population and group structure may influence HPA activation. Hair samples (n = 282) were analyzed from 113 females and 135 males. Females with dependent offspring (foals) had higher HCC than those females without dependent offspring (p = 0.005). Horses in poor body condition were also more likely to have higher HCC (females: p &lt; 0.001, males: p = 0.028); females had greater variation in the body condition index (BCI), which also correlated with foal production. In general, the top-ranked models describing female cortisol levels included age, BCI, presence of a foal, as well as social measures such as harem size and the number of bachelors in the vicinity. The top model describing male cortisol levels included age, BCI, and year of collection only, and the number of bachelors in the home range appeared in subsequent, though still high-ranked, models. Among the variables not of direct interest, we found some significant results relating to hair color and hair texture. Differences in HCC patterns between feral and domestically kept horses (e.g., age and sex) are likely linked to periods of resource limitations, particularly for individuals experiencing energetically demanding processes such as reproduction, illness/parasitism, or related to experiencing the full range of social and reproductive behaviors.

Hair Cortisol and Perceived Stress-Predictors for the Onset of Tics? A European Longitudinal Study on High-Risk Children.

Some retrospective studies suggest that psychosocial stressors trigger the onset of tics. This study examined prospective hypothalamic-pituitary-adrenal (HPA) axis activity and perceived stress prior to tic onset. In the present study, 259 children at high risk for developing tics were assessed for hair cortisol concentration (HCC) and parent-on-child-reported perceived stress four-monthly over a three-year period. We used (i) generalised additive modelling (GAM) to investigate the time effects on HCC (hair samples n = 765) and perceived stress (questionnaires n = 1019) prior to tic onset and (ii) binary logistic regression to predict tic onset in a smaller subsample with at least three consecutive assessments (six to nine months before, two to five months before, and at tic onset). GAM results indicated a non-linear increasing course of HCC in children who developed tics, and a steady HCC course in those without tics, as well as a linear-increasing course of perceived stress in both groups. Logistic regression showed that with a higher HCC in hair samples collected in a range of two to five months before tic onset (which refers to cortisol exposure in a range of four to eight months), the relative likelihood of tic onset rose. Our study suggests increased stress prior to tic onset, as evidenced by higher HCC several months before tic onset.

Are hair cortisol levels dependent on hair growth rate? A pilot study in rhesus macaques

Research incorporating the analysis of glucocorticoids, specifically cortisol, in hair samples has exploded over the past 10–15 years, yet factors contributing to the accumulation of cortisol in hair are not yet fully characterized. In particular, it is not clear whether cortisol accumulation in hair is dependent on hair growth rate, a possibility raised by prior rodent studies reporting glucocorticoid-mediated inhibition of hair growth. Using rhesus macaque monkeys (Macaca mulatta), an extensively studied nonhuman primate species, the present pilot study evaluated the hypothesis that hair cortisol accumulation is inversely related to hair growth rate (i.e., slower hair growth leading to elevated cortisol levels). Hair samples were collected from 19 adult female macaques and 17 infants (9 males) 3 months apart using a shave-reshave procedure from the same site below the posterior vertex of the scalp. The second hair samples were measured to the nearest millimeter (mm) for growth rate over the previous 3 months and assayed for hair cortisol concentrations (HCCs) using enzyme immunoassay. Because of the possibility of age-related differences in hair growth rate, correlational analyses were performed separately for adults and infants to determine whether HCC values were associated with growth rate in each age group. These analyses revealed that neither group displayed a significant correlation of HCCs with hair growth. The results additionally showed that overall, adults had a faster hair growth rate than infants and, as expected from previous studies, had lower HCCs than infants. Our results suggest that higher HCCs within the non-stress range do not result from cortisol-mediated inhibition of hair growth. Moreover, similarities between humans and macaque monkeys in both HPA axis regulation and hair growth rates argue that these findings are relevant for human hair cortisol studies. Extrapolation to other species in which the features of hair growth and the relevant regulatory mechanisms are less well understood should be done with caution.

Teachers' perception of aggressive student behavior through the lens of chronic worry and resignation, and its association with psychophysiological stress: An observational study

Aggressive student behavior is considered a leading risk factor for teacher stress. However, teachers' coping styles may affect how they perceive and respond to aggressive student behavior. This study tests whether teachers' perceptions of aggressive student behavior mainly mirror objectively observed aggression in presence of the teacher (as coded by external observers) or whether teachers' perception of aggressive student behavior primarily reflects teachers' avoidant coping styles, such as chronic worry and resignation. Finally, we examine whether observed and teacher-perceived aggression relates to increased vital exhaustion and psychophysiological stress among teachers (i.e., higher hair cortisol concentration). In an ambulatory assessment study, we administered self-reports to 42 Swiss teachers to assess perceived student aggression, chronic worry, resignation, and vital exhaustion. Additionally, four consecutive lessons per teacher were filmed, and aggressive student behavior in presence of the teacher was coded by four trained external observers. The concentration of cortisol was assessed in hair samples. Results showed that teacher-perceived and observed aggression were moderately associated. Observed aggression was related to teacher perceptions to a much lesser extent than teachers' avoidant coping styles, that is, chronic worry and resignation. While teacher-perceived student aggression was associated with teachers' self-reported vital exhaustion, we did not find any significant association with hair-cortisol concentration. Our findings suggest that teachers perceive student aggression through the lens of their coping styles. Teachers' dysfunctional coping styles are associated with an overestimation of student aggression. Teachers' overestimation of student aggression relates to higher levels of vital exhaustion. Therefore, it is crucial to identify and change teachers' dysfunctional coping styles to prevent a vicious cycle of dysfunctional teacher–student interactions.

Associations between hair cortisol and blood pressure: a systematic review and meta-analysis.

Stress is widely considered to be a risk factor for high blood pressure (BP), but evidence on the associations between biomarkers of chronic stress and BP is inconsistent. This systematic review and meta-analysis assessed the current state of the science on relationships between measures of cortisol concentration reflecting chronic stress exposure [hair cortisol concentration (HCC), nail cortisol concentration)] and BP. PubMed, Cumulative Index to Nursing and Allied Health Literature, Web of Science, Cochrane Library, and Embase were searched. Random effects models were used to assess the pooled effect size. Exploratory moderation analysis was performed. Out of 34 014 identified, 16 articles met eligibility criteria and were included in the review, while 14 were included in the meta-analysis. No articles were reported on the association between nail cortisol concentration and BP. Small, positive associations were observed between HCC and SBP [ r = 0.19 (95% confidence interval (CI): 0.08-0.29)] and HCC and DBP [ r = 0.13 (95% CI: 0.04-0.22)]. Cortisol analysis method was identified as a significant moderator of the association between HCC and DBP. HCC was largely, positively associated with hypertension status [odds ratio = 3.23 (95% CI: 2.55-4.09), P < 0.001]. Current evidence suggests that higher HCC may be associated with elevated BP and a potential risk factor for hypertension. However, results should be interpreted with caution because HCC can be affected by hair color, hair care products, and analytic methods. Given the limitations of studies included in this review, further research is needed.

Everyday perceptions of safety and racial disparities in hair cortisol concentration

ObjectiveBlack-White disparities in physiological stress during adolescence are increasingly evident but remain incompletely understood. We examine the role of real-time perceptions of safety in the context of everyday routines to gain insight into the sources of observed adolescent racial differences in chronic stress as measured by hair cortisol concentration (HCC). MethodWe combined social survey, ecological momentary assessment (EMA), and hair cortisol data on 690 Black and White youth ages 11–17 from wave 1 of the Adolescent Health and Development in Context (AHDC) study to investigate racial differences in physiological stress. Individual-level, reliability-adjusted measures of perceived unsafety outside the home were drawn from a week-long smartphone-based EMA and tested for association with hair cortisol concentration. ResultsWe observed a statistically significant interaction (p < .05) between race and perceptions of unsafety. For Black youth, perceived unsafety was associated with higher HCC (p < .05). We observed no evidence of an association between perceptions of safety and expected HCC for White youth. For youth who perceive their out-of-home activity locations to be consistently safe, the racial difference in expected HCC was not statistically significant. At the high end of perceived unsafety, however, Black-White differences in HCC were pronounced (0.75 standard deviations at the 95th percentile on perceived unsafety; p < .001). DiscussionThese findings call attention to the role of everyday perceptions of safety across non-home routine activity contexts in explaining race differences in chronic stress as assessed by hair cortisol concentrations. Future research may benefit from data on in situ experiences to capture disparities in psychological and physiological stress.

Abstract MP35: Hair Cortisol Concentrations Are Associated With Greater Adiposity in Mid-Adolescence

Introduction: Hair cortisol concentration (HCC) is a biomarker of long-term stress. Higher HCC is associated with body mass index (BMI) and other adiposity measures in adults; however, this association is not well characterized in adolescents. Additionally, HCC differs by sex, but associations with adiposity by sex have not been well studied. Hypothesis: Higher HCC levels are associated with greater adiposity in mid-adolescence. Methods: Among 324 participants (49.1% female, mean 17.7 years) in Project Viva, we performed a cross-sectional analysis of HCC with measures of adiposity in mid-adolescence. We used multivariable linear regression models, overall and stratified by sex, to estimate associations of HCC (log2 transformed) with BMI, % body fat, and waist circumference (WC), adjusted for age and known predictors of adiposity, namely maternal education, smoking during pregnancy, pre-pregnancy BMI, age, and household income; and child sex-specific birthweight for gestational age z-scores, secondhand smoke exposure, age, and sex (for overall models). Results: Median (IQR) HCC was 2.1 pm/mg (1.0 – 4.7) and mean (SD) BMI was 23.0 kg/m 2 (3.8), % body fat was 20.1% (9.9), and WC was 80.4 cm (10.8). In adjusted models, HCC (per doubling) was associated with higher BMI (β 0.20 kg/m 2 ; 95% CI 0.01, 0.39), % body fat (β 0.42%; 95% CI 0.04, 0.80), and WC (β 0.45 cm; 95% CI -0.07, 0.96) (Figure). There was no evidence of effect modification by sex (all sex by HCC interaction p-values &gt;0.50). Conclusions: Higher HCC was cross-sectionally associated with greater adiposity in mid-adolescence. Associations were similar among males and females, suggesting a similar impact of long-term stress on adiposity between sexes. Adjustment for known predictors of adiposity does not alter the association of HCC and adiposity measures. Further research is needed to understand the temporal direction of this association.

When asking ‘are you stressed?’ is not enough: Hair cortisol, subjective stress, and alcohol use during the first year of the pandemic

The onset of the COVID-19 pandemic was accompanied by an increase in alcohol use in a third of the population worldwide. To date, the literature shows that subjective reports of stress predicted increased alcohol use during the early stages of the pandemic. However, no studies have investigated the effect of physiological stress (via the stress hormone cortisol) on alcohol use during the pandemic. This study aimed to identify the predictive value of cortisol and/or subjective stress on alcohol use during the first year of the pandemic. Every three months, between June 2020 and March 2021, 79 healthy adults (19–54 years old) answered online questionnaires assessing alcohol use. In May 2020, participants reported pre-pandemic alcohol use, while in June 2020, participants reported current alcohol use, subjective stress measures, and provided a 6 cm hair sample. The latter allowed us to quantify the cumulative levels of cortisol produced in the three months prior to and following the start of the mandatory lockdown measures in March 2020 in Quebec, Canada. A relative change in hair cortisol was computed to quantify the physiological stress response. While controlling for sex, age, and psychiatric diagnoses, multilevel linear regressions revealed that alcohol use increased only among people with concomitant high subjective stress and elevated hair cortisol concentrations. Moreover, this increased alcohol use remained elevated one year later. This study documents the importance of simultaneously considering stress biomarkers and subjective stress to identify people at risk of increasing their alcohol use during major stressful life events.

Chronic stress is associated with specific path integration deficits

Repeated exposure to stress (chronic stress) can cause excess levels of circulating cortisol and has detrimental influences on various cognitive functions including long-term memory and navigation. However, it remains an open question whether chronic stress affects path integration, a navigational strategy that presumably relies on the functioning of grid cells in the medial entorhinal cortex. The entorhinal cortex is a brain region in the medial temporal lobe, which contains multiple cell types involved in spatial navigation (and episodic memory), and a high number of corticosteroid receptors, predisposing it as a potential target of cortisol effects. Here, our goal was to investigate the association between chronic stress and path integration performance. We assessed chronic stress via hair cortisol concentration (physiological measure) and the Perceived Stress Questionnaire (subjective measure) in 52 female participants aged 22–65 years. Path integration was measured using a virtual homing task. Linear mixed models revealed selective impairments associated with chronic stress that depended on error type and environmental features. When focusing on distance estimations in the path integration task, we observed a significant relationship to hair cortisol concentrations indicating impaired path integration particularly during trials with higher difficulty in participants with high hair cortisol concentrations. This relationship especially emerged in the absence of spatial cues (a boundary or a landmark), and particularly in participants who reported high levels of subjectively experienced chronic stress. The findings are in line with the hypothesis that chronic stress compromises path integration, possibly via an effect on the entorhinal grid cell system.

The mane factor: Compliance is associated with increased hair cortisol in the horse

Equine personality tests enable the selection of horses for roles based on their habitual behavioural responses to challenges, aiming to maximise performance and safeguard equine welfare. However, existing research has identified that behavioural responses to acute challenges do not correlate well with stress physiology in the horse. The aim of this study was to investigate whether chronic stress physiology is related to habitual compliance in horses. Hair cortisol concentration (HCC), a long-term biomarker of hypothalamic–pituitary–adrenal axis activity and stress, was assayed in mane hair from the withers, midpoint of the neck and poll of 24 riding school horses (66% male, mean age 13 ± 4 years). Three caregivers provided scores for Agreeableness, Neuroticism, Extroversion, Gregariousness Towards People and Gregariousness Towards Horses for all subjects using a validated equine personality questionnaire. A gamma GLMM was used to model HCC as a function of personality scores and potential confounders of HCC (age, sex, hair colour and sampling location). Individual horses were fitted as random intercepts in the model. Manual backward selection was used to identify the best-fitting plausible model. Mean HCC was 3.8 ± 1.2 pg/mg. The final model only retained Agreeableness and sampling location as explanatory variables of HCC. A positive association was found between Agreeableness (reflecting habitual compliance) and hair cortisol concentration (t = 2.7, p = 0.01). Basal cortisol levels are known to drive sensitivity to punishment in humans. Therefore, horses with higher basal cortisol may be more sensitive to the aversive cues associated with negative reinforcement and consequently be more compliant. However, it is also possible that habitually compliant behaviour leads to higher chronic stress levels through increased exposure to stressors, as more subtle expressions of discomfort are not recognised by handlers. This result has important implications for welfare in the context of horse-human interaction and warrants further investigation to clarify whether a causal link exists between habitual compliance and higher levels of chronic stress. There was also a weaker but significant impact of sampling location (t = 2.1, p = 0.03; higher HCC at the poll), highlighting the importance of carefully standardizing sampling location for HCC analysis.

Unemployment and hair cortisol as a biomarker of chronic stress

Unemployment is widely considered an important chronic stressor. Using longitudinal data of initially employed German jobseekers, the present study examines whether unemployment is related to changes in hair cortisol concentration (HCC), a reliable biomarker for chronic stress. The results indicate that HCC is the highest initially when individuals are insecurely employed and decreases as people gain certainty about whether they enter unemployment or not. We find no effects when comparing the average changes in HCC between individuals who entered unemployment to those of continuously employed individuals. However, medium-term unemployment was associated with a stronger mean increase in HCC if re-employment expectations were low compared to when re-employment expectations were high. Taken together, our results support two key conclusions. First, experiencing the uncertainty of looming unemployment is associated with more pronounced cortisol secretion than unemployment itself. Second, whether working or being unemployed is associated with higher HCC is highly context-dependent, with poor re-employment prospects during unemployment being a key predictor of increased HCC. Overall, our study provides further evidence that the physiological stress system is especially sensitive to uncontrollable situations and unfamiliar challenge.

Relationship between proximity and physiological stress levels in hunter-gatherers: The Hadza

In recent years there has been a great deal of documentation on how social relationships are related to various aspects of human wellbeing. However, until recently most studies investigating the effects of social relationships on wellbeing have applied social network measures to reported social contacts. Recent advances in the application of bio-loggers in biological studies have now made it possible to quantify social relationships based on in-person, rather than self-reported, social interactions. We used GPS-derived in-camp and out-of-camp proximity data to analyse how in-person proximity is related to Hair Cortisol Concentration (HCC) among Hadza hunter-gatherers. Time spent in close proximity to other camp members was associated with higher HCC, especially in women. In contrast, individuals who spent more time in close out-of-camp proximity to their best friend experienced lower HCC. Our study suggests that physiological costs related to group living might be mitigated by in-person interactions with close friends. We also find that the location (i.e., in-camp vs out-of-camp) of proximity to others and self-perceived friends is associated with HCC among the Hadza.