Hair analysis provides a historical record of cortisol levels in Cushing's syndrome

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.

Impact of repeated anesthesia with ketamine and xylazine on the well-being of C57BL/6JRj mice

Within the scope of the 3Rs of Russel and Burch, the number of laboratory animals can be reduced by repeated use of an animal. This strategy only becomes relevant, if the total amount of pain, distress or harm the individual animal experiences does not exceed the severity of a single manipulation. For example, when using imaging techniques, an animal can be examined several times during a study, but it has to be anesthetized each time imaging is performed. The severity of anesthesia is thought to be mild according to the Directive 2010/63/EU. However, the Directive does not differentiate between single and repeated anesthesia, although repeated anesthesia may have a greater impact on well-being. Hence, we compared the impact of single and repeated anesthesia (six times at an interval of three to four days) by injection of ketamine and xylazine (KX) on the well-being of adult female and male C57BL/6JRj mice. After anesthesia, well-being of mice was assessed according to a protocol for systematic assessment of well-being including nesting, the Mouse Grimace Scale (MGS), a test for trait anxiety, home cage activity, and the rotarod test for motor activity, food intake, and body weight, as well as corticosterone (metabolite) analysis. Repeated anesthesia increased the MGS in mice of both sexes and caused short-term effects on well-being of female mice in the immediate post-anesthetic period, indicated by longer lasting effects on trait anxiety-related behavior. However, corticosterone metabolite concentrations suggested that mice habituated to the stress induced by repeated KX administration. Hence, the mildly negative effects on well-being of repeated KX anesthesia do not seem to accumulate over time using the respective regimen. However, further observations for severity classification are warranted in order to more specifically determine the duration of mild distress and trait anxiety.

Mini-review of hair cortisol concentration for evaluation of Cushing syndrome

INTRODUCTION

The diagnosis of endogenous Cushing syndrome is often challenging and requires multiple repeated blood, urine, and saliva tests to detect elevated cortisol levels. Hair cortisol concentration has been described as a marker of long-term exposure to systemic cortisol in patients with Cushing syndrome. Like hemoglobin A1c is used to detect serum glucose exposure over months, segmental hair cortisol can help identify patients with milder forms of and/or periodic or cyclical Cushing syndrome, which may reduce time and costs associated with collection of urine, salivary, and serum cortisol.

AREAS COVERED

Success of hair cortisol in detection of Cushing syndrome will be discussed in context of current literature, including differences between total or segmental hair cortisol in accurately determining timeline of cortisol exposure. Optimal methods of hair collection, storage, processing, and analysis and efforts toward standardization will be a major focus.

EXPERT COMMENTARY

Recent evidence suggests increased sensitivity and specificity of hair cortisol in detecting Cushing syndrome. Future guidelines should consider this test as a routine part of the repertoire of screening tests for Cushing syndrome. Possible confounders to explain discrepant results in the literature will be discussed.

The effects of body region, season and external arsenic application on hair cortisol concentration

Hair cortisol analysis has been used to quantify hormone levels in circulation in several mammal species. Hair remains stable for decades or centuries, allowing researchers to use archived hair samples to investigate hormone levels that span long time periods. However, several studies have found that intra-individual variability, driven by the body region from which a sample is derived, confounds measurements of systemic glucocorticoid hormone concentrations. In addition, the external application of chemical agents to hair can remove or concentrate molecules of interest. These may preclude the use of samples that have been collected opportunistically and/or those that have been housed in museum collections. Using a captive population of Vancouver Island marmots (Marmota vancouverensis), we found a strong effect of body region on the concentration of cortisol within hair, as well as an effect of season. Using a collection of American mink (Neovison vison) pelts, we found that application of the preservative arsenic in the form of a soap does not cause a significant decrease in cortisol. The marmot results suggest that intra-individual variability is not stable through time. The reason for these seasonal effects is not clear and further study is necessary. Researchers using samples from an unknown body region should exercise caution in interpreting their results. The mink results suggest that samples held in museum collections can be used to quantify cortisol, even when arsenic preservation is suspected.

Comparison of blood sampling methods for plasma corticosterone measurements in mice associated with minimal stress-related artefacts

Accurate measurement of circulating glucocorticoid concentrations in rodents is often hampered by the stress-related activation of the hypothalamic-pituitaryadrenal axis during animal handling. The present study aims to identify methods of blood collection associated with minimal stress and thus artificial increases in plasma glucocorticoid levels. Using two strains of mice, we evaluated common laboratory methods of non-terminal (tail blood sampling with or without restraint; retro-orbital puncture) and terminal blood collection (cardiac puncture) and their immediate and prolonged effect on plasma corticosterone levels. Compared to retro-orbital and cardiac puncture, mice from both the unrestrained and restrained tail snip collection groups displayed the lowest plasma corticosterone levels in both mouse strains. Plasma corticosterone levels in samples obtained from retro-orbital and cardiac puncture collection were up to twenty times higher than those measured in mice undergoing blood collection via tail snip. Repeat tail snip collections (every 30 min for 120 min, or once after 120 min) revealed sustained hypercortisolaemia, compared to the initial collection. We conclude that blood sampling via tail snip without restraint remains the gold-standard method of collection that is associated with minimal stress-related artefacts and hence feasible for single time point corticosterone analyses.

Short communication: Is hair cortisol a potential indicator for stress caused by chronic lameness in dairy cows?

The objective of this study was to evaluate hair cortisol concentration as an indicator for stress caused by chronic lameness in dairy cows. Sixty-eight cows were scored for lameness for 4 consecutive weeks. The hair of the tail switch was clipped at the beginning of the study and regrown hair was clipped after 4 wk. Hair samples were analyzed for cortisol concentration. Animals with 2 consecutive locomotion scores ≥3 or with an overall mean score >1.5 were classified as lame. After pair matching lame and nonlame cows, considering days in milk, lactation number, and milk yield, and excluding cows with less than 20 mg hair sample for analysis, 21 lame and 21 nonlame cows were included in the analysis. The mean hair cortisol concentration in this study was 2.32 ± 0.35 pg/mg (mean ± standard deviation). Cortisol concentration from hair regrown in the study period was 2.38 ± 0.95 and 2.26 ± 1.35 pg/mg for lame and nonlame cows (n = 21), respectively; we found no difference in mean cortisol level of primiparous and multiparous cows. Based on these data, hair cortisol concentration was not a useful indicator to differentiate cows with chronic lameness and healthy cows.

Hair cortisol concentrations in war-affected adolescents: A prospective intervention trial

Temporal examinations of the biological signature of stress or trauma in war-affected populations are seldom undertaken. Moreover, few studies have examined whether stress biomarkers track biological sensitivity to brief interventions targeting the improvement of psychosocial wellbeing. Our study is the first to prospectively examine, in war-affected adolescents, the associations between hair cortisol concentrations (HCC) and self-reports of stress, insecurity, posttraumatic reactions, and lifetime trauma. We conducted a randomized controlled trial to test the impact of an 8-week intervention based on profound stress attunement. We collected data for a gender-balanced sample of 733 Syrian refugee (n = 411) and Jordanian non-refugee (n = 322) adolescents (12-18 years), at three time-points. We used growth mixture models to classify cortisol trajectories, and growth models to evaluate intervention impact on stress physiology. We observed three trajectories of HCC: hypersecretion, medium secretion, and hyposecretion (9.6%, 87.5% and 2.9% of the cohort, respectively). For every one percent increase in levels of insecurity, adolescents were 0.02 times more likely to have a trajectory of hypersecretion (95% CI: 1.00, 1.03, p = 0.01). For each additional symptom of posttraumatic stress reported, they were 0.07 times less likely to show hyposecretion (95% CI: 0.89, 0.98, p = 0.01). Indeed, stronger posttraumatic stress reactions were associated with a pattern of within-individual cortisol dysregulation and medium secretion. Overall, HCC decreased by a third in response to the intervention (95% CI: -0.19, -0.03, p = 0.01). While the intervention decreased HCC for youth with hypersecretion and medium secretion, it increased HCC for youth with hyposecretion (95% CI: 0.22, 1.16, p = 0.004), relative to controls. This suggests a beneficial regularization of cortisol levels, corroborating self-reports of improved psychosocial wellbeing. We did not find evidence to suggest that gender, resilience, or posttraumatic stress disorder influenced the strength or direction of responses to the intervention. This robust impact evaluation exemplifies the utility of biomarkers for tracking physiological changes in response to interventions over time. It enhances the understanding of trajectories of endocrine response in adverse environments and patterns of stress responsivity to ecological improvement.

Hair corticosterone measurement in mouse models of type 1 and type 2 diabetes mellitus

In diabetes, glucocorticoid secretion increases secondary to hyperglycemia and is associated with an extensive list of disease complications. Levels of cortisol in humans, or corticosterone in rodents, are usually measured as transitory biomarkers of stress in blood or saliva. Glucocorticoid concentrations accumulate in human or animal hair over weeks and could more accurately measure the cumulative stress burden of diseases like chronic diabetes. In this study, corticosterone levels were measured in hair in verified rodent models of diabetes mellitus. To induce type 1 diabetes, C57BL/6J mice were injected with streptozotocin and blood and hair samples were collected 28days following induction. Leptin receptor deficient (db/db) mice were used as a spontaneous model of type 2 diabetes and blood and hair samples were collected at 8weeks of age, after the development of hyperglycemia and obesity. Corticosterone levels from serum, new growth hair and total growth hair were analyzed using an enzyme immunoassay. Corticosterone levels in new growth hair and serum were significantly elevated in both models of diabetes compared to controls. In contrast, corticosterone levels in old hair growth did not differ significantly between diabetic and non-diabetic animals. Thus, hair removal and sampling of new hair growth was a more sensitive procedure for detecting changes in hair corticosterone levels induced by periods of hyperglycemia lasting for 4weeks in mice. These results validate the use of hair to measure long-term changes in corticosterone induced by diabetes in rodent models. Further studies are now needed to validate the utility of hair cortisol as a tool for measuring the stress burden of individuals with diabetes and for following the effects of long-term medical treatments.

Hypothalamic Dysfunction and Multiple Sclerosis: Implications for Fatigue and Weight Dysregulation

Signs and symptoms of multiple sclerosis are usually attributed to demyelinating lesions in the spinal cord or cerebral cortex. The hypothalamus is a region that is often overlooked yet controls many important homeostatic functions, including those that are perturbed in multiple sclerosis. In this review we discuss how hypothalamic dysfunction may contribute to signs and symptoms in people with multiple sclerosis. While dysfunction of the hypothalamic-pituitary-adrenal axis is common in multiple sclerosis, the effects and mechanisms of this dysfunction are not well understood. We discuss three hypothalamic mechanisms of fatigue in multiple sclerosis: (1) general hypothalamic-pituitary-adrenal axis hyperactivity, (2) disordered orexin neurotransmission, (3) abnormal cortisol secretion. We then review potential mechanisms of weight dysregulation caused by hypothalamic dysfunction. Lastly, we propose future studies and therapeutics to better understand and treat hypothalamic dysfunction in multiple sclerosis. Hypothalamic dysfunction appears to be common in multiple sclerosis, yet current studies are underpowered and contradictory. Future studies should contain larger sample sizes and standardize hormone and neuropeptide measurements.

High hair cortisol concentrations predict worse cognitive outcome after stroke: Results from the TABASCO prospective cohort study

BACKGROUND AND PURPOSE

The role of stress-related endocrine dysregulation in the development of cognitive changes following a stroke needs further elucidation. We explored this issue in a longitudinal study on stroke survivors using hair cortisol concentrations (HCC), a measure of integrated long-term cortisol levels.

METHODS

Participants were consecutive cognitively intact first-ever mild-moderate ischemic stroke/transient ischemic attack (TIA) survivors from the Tel Aviv Brain Acute Stroke Cohort (TABASCO) study. They underwent 3T magnetic resonance imaging (MRI) scanning and were cognitively assessed at admission, and at 6, 12 and 24 months post-stroke. Scalp hair samples were obtained during the initial hospitalization.

RESULTS

Full data on baseline HCC, MRI scans and 2 years neuropsychological assessments were available for 65 patients. Higher HCC were significantly associated with a larger lesion volume and with worse cognitive results 6, 12 and 24 months post-stroke on most of the neurocognitive tests. 15.4% of the participants went on to develop clinically significant cognitive decline in the follow-up period, and higher HCC at baseline were found to be a significant risk factor for this decline, after adjustment for age, gender, body mass index and APOE e4 carrier status (HR=6.553, p=0.038).

CONCLUSIONS

Our findings suggest that individuals with higher HCC, which probably reflect higher long-term cortisol release, are prone to develop cognitive decline following an acute stroke or TIA.

A UHPLC-MS/MS method for profiling multifunctional steroids in human hair

It is important to profile steroids in many physiological and pathological processes. Recently, hair has been used for the long-term measurement of endogenous steroid hormones. Analyzing hair has advantages of being noninvasive and time sequential compared with other bio-specimens. Liquid chromatography-mass spectrometry (LC-MS) techniques have been widely used over the past decades; however, it is challenging to profile estrogens in hair by LC-MS, and more comprehensive steroid profiling is required. In this paper, an ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed to simultaneously profile 28 multifunctional steroids, including corticosteroids (n = 6), estrogens (n = 13), androgens (n = 5) and progestogens (n = 4), in human scalp hair in a single run. To optimize the sample preparation procedure, we evaluated extraction time, post-incubation purification and hair fragment length; 30 mg hair samples were washed with hexane, cut into 5 mm pieces and incubated in methanol for 18 h at 25 °C. Methanol extraction derivatized using Girard P and dansyl chloride reagent was analyzed within 25 min using an automated injection program combined with a diverter valve switch and step analysis (AIDSA). The method was well validated in terms of linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, matrix effect and recovery, and was successfully applied to a steroid profile from male and female hairs. Significant differences were observed between genders. In addition, steroids showed a declining trend from the proximal to more distal hair segments; thus, care should be taken when obtaining hair samples for analysis to account for this difference in steroid levels along the length of hair. Graphical Abstract The workflow of the estabished UHPLC-MS/MS method.

Severity classification of repeated isoflurane anesthesia in C57BL/6JRj mice-Assessing the degree of distress

According to the EU Directive 2010/63, the severity of a procedure has to be classified as mild, moderate or severe. General anesthesia is thought to be mild, but the Directive does not differentiate between single and repeated anesthesia. Therefore, we investigated the impact of repeated administration of isoflurane, the most commonly used inhalation anesthetic, on the well-being of adult C57BL/6JRj mice, in comparison to single administrations and to untreated animals, when applied six times for 45 min at an interval of 3–4 days. For the animals anesthetized, excitations, phases of anesthesia, and vital parameters were monitored. Well-being after anesthesia was assessed using a behavioral test battery including luxury behavior like burrowing and nest building behavior, the Mouse Grimace Scale (MGS), the free exploratory paradigm for anxiety-related behavior, home cage activity and the rotarod test for activity, as well as food intake and body weight. Additionally, hair corticosterone and fecal corticosterone metabolites were measured. Our results show that nest building behavior, home cage activity, body weight, and corticosterone concentrations were not influenced by anesthesia, whereas changes in burrowing behavior, the MGS, food intake, and the free exploratory behavior indicated that the well-being of the mice was more affected by repeated than single isoflurane anesthesia. This effect depended on the sex of the animals, with female mice being more susceptible than male mice. However, repeated isoflurane anesthesia caused only short-term mild distress and impairment of well-being, mainly in the immediate postanesthetic period. Well-being stabilized at 8 days after the last anesthesia, at the latest. Therefore, we conclude that when using our anesthesia protocol, the severity of both single and repeated isoflurane anesthesia in C57BL/6JRj mice can be classified as mild. However, within the mild severity category, repeated isoflurane anesthesia ranks higher than single isoflurane anesthesia. Additionally, our results imply that male and female mice can differently perceive the severity of a procedure.

Scalp hair cortisol for diagnosis of Cushing's syndrome

OBJECTIVE

Current first-line screening tests for Cushing's syndrome (CS) only measure time-point or short-term cortisol. Hair cortisol content (HCC) offers a non-invasive way to measure long-term cortisol exposure over several months of time. We aimed to evaluate HCC as a screening tool for CS.

DESIGN

Case-control study in two academic referral centers for CS.

METHODS

Between 2009 and 2016, we collected scalp hair from patients suspected of CS and healthy controls. HCC was measured using ELISA. HCC was available in 43 confirmed CS patients, 35 patients in whom the diagnosis CS was rejected during diagnostic work-up and follow-up (patient controls), and 174 healthy controls. Additionally, we created HCC timelines in two patients with ectopic CS.

RESULTS

CS patients had higher HCC than patient controls and healthy controls (geometric mean 106.9 vs 12.7 and 8.4 pg/mg respectively, P < 0.001). At a cut-off of 31.1 pg/mg, HCC could differentiate between CS patients and healthy controls with a sensitivity of 93% and a specificity of 90%. With patient controls as a reference, specificity remained the same (91%). Within CS patients, HCC correlated significantly with urinary free cortisol (r = 0.691, P < 0.001). In two ectopic CS patients, HCC timelines indicated that cortisol was increased 3 and 6 months before CS became clinically apparent.

CONCLUSIONS

Analysis of cortisol in a single scalp hair sample offers diagnostic accuracy for CS similar to currently used first-line tests, and can be used to investigate cortisol exposure in CS patients months to years back in time, enabling the estimation of disease onset.

Hair cortisol in the evaluation of Cushing syndrome

PURPOSE

Hair cortisol evaluation has been used to help detect patients with suspected Cushing syndrome. Our goal was to correlate segmental hair cortisol with biochemical testing in patients with Cushing syndrome and controls. This study was a prospective analysis of hair cortisol in confirmed Cushing syndrome cases over 16 months.

METHODS

Thirty-six subjects (26.5 ± 18.9 years, 75% female, and 75% Caucasian) were analyzed by diurnal serum cortisol, 24 h urinary free cortisol corrected for body surface area (UFC/BSA), and 24 h urinary 17-hydroxysteroids corrected for creatinine (17OHS/Cr). Thirty patients were diagnosed with Cushing syndrome, and six were defined as controls. 3-cm hair samples nearest to the scalp, cut into 1-cm segments (proximal, medial, and distal), were analyzed for cortisol by enzyme immunoassay and measured as pmol cortisol/g dry hair. Hair cortisol levels were compared with laboratory testing done within previous 2 months of the evaluation.

RESULTS

Proximal hair cortisol was higher in Cushing syndrome patients (266.6 ± 738.4 pmol/g) than control patients (38.9 ± 25.3 pmol/g) (p = 0.003). Proximal hair cortisol was highest of all segments in 25/36 (69%) patients. Among all subjects, proximal hair cortisol was strongly correlated with UFC/BSA (r = 0.5, p = 0.005), midnight serum cortisol (r = 0.4, p = 0.03), and 17OHS/Cr, which trended towards significance (r = 0.3, p = 0.06).

CONCLUSIONS

Among the three examined hair segments, proximal hair contained the highest cortisol levels and correlated the most with the initial biochemical tests for Cushing syndrome in our study. Further studies are needed to validate proximal hair cortisol in the diagnostic workup for Cushing syndrome.

Hair cortisol and adiposity in a population-based sample of 2,527 men and women aged 54 to 87 years

OBJECTIVE

Chronic cortisol exposure is hypothesized to contribute to obesity. This study examined associations between hair cortisol concentrations, a novel indicator of long-term cortisol exposure, and adiposity in a large population-based sample.

METHODS

Data were from 2,527 men and women aged 54 and older (98% white British) participating in the English Longitudinal Study of Ageing. Hair cortisol concentrations were determined from the scalp-nearest 2 cm hair segment, and height, weight, and waist circumference were objectively measured. Covariates included age, sex, socioeconomic status, smoking status, diabetes, and arthritis.

RESULTS

In cross-sectional analyses, hair cortisol concentrations were positively correlated with weight (r = 0.102, P < 0.001), BMI (r = 0.101, P < 0.001), and waist circumference (r = 0.082, P = 0.001) and were significantly elevated in participants with obesity (BMI ≥30 kg/m² ) (F = 6.58, P = 0.001) and raised waist circumference (≥102 cm in men, ≥88 cm in women) (F = 4.87, P = 0.027). Hair cortisol levels were also positively associated with the persistence of obesity (F = 12.70, P < 0.001), evaluated in retrospect over 4 years.

CONCLUSIONS

Chronic exposure to elevated cortisol concentrations, assessed in hair, is associated with markers of adiposity and with the persistence of obesity over time.

Stress-related and basic determinants of hair cortisol in humans: A meta-analysis

The analysis of hair cortisol concentrations (HCC) is a relatively new strategy to measure long-term cumulative cortisol levels, which is increasingly used in psychoneuroendocrinological research. Here, we conduct a first comprehensive meta-analysis of HCC research based on aggregated data from a total of 124 (sub)samples (66 independent studies; total N=10,289). We seek to answer two central questions: (i) Which covariates and basic features of HCC need to be considered in future research? (ii) What are the main determinants of HCC in terms of chronic stress exposure and mental health? Concerning basic characteristics, our findings identify several covariates to be considered (age, sex, hair washing frequency, hair treatment, oral contraceptive use), confirm a decline of HCC from the first to the second proximal 3cm hair segment, and show positive associations between HCC and short-term salivary cortisol measures. Regarding chronic stress, we show that stress-exposed groups on a whole exhibit 22% increased HCC. This long-term cortisol hypersecretion emerges particularly when stress is still ongoing at the time of study (+43% HCC) but is not present in conditions of past/absent stress (-9% HCC, n.s.). We also report evidence for 17%-reduced HCC in anxiety disorders, such as PTSD. Interestingly, no consistent associations with mood disorders and self-reports of perceived stress, depressiveness or social support are found. However, our findings reveal positive associations of HCC with stress-related anthropometric (body mass index, waist-to-hip ratio) and hemodynamic measures (systolic blood pressure). These meta-analytic results are discussed in the light of their practical implications and important areas for future inquiry are outlined.

Maternal prenatal stress and child atopic dermatitis up to age 2 years: The Ulm SPATZ health study

BACKGROUND

Evidence linking maternal psychosocial stress during pregnancy to subsequent child atopic dermatitis (AD) is growing, but the definition of AD is diverse and results are inconsistent. We aimed to analyze the relationship between stress and AD using alternative measurements of stress and AD.

METHODS

In the Ulm SPATZ Health Study, chronic stress and symptoms of anxiety and depression were assessed by standardized self-reported questionnaires in 934 mothers of singletons following delivery in Ulm, Germany, from 04/2012-05/2013. Maternal hair cortisol concentrations (HCCs, n = 626) at childbirth and the cumulative incidences of parent-reported child AD symptoms, parent-, and pediatrician-reported AD diagnoses were assessed until age 2 years (n = 787). Overall, 205 dermatologic examinations were performed in 167 children showing AD symptoms. Crude and adjusted risk ratios (RR, aRR) with 95% confidence intervals were estimated.

RESULTS

Maternal stress and anxiety were associated with child AD symptoms by trend (RR and aRR: 1.5 (1.0,2.3) for the highest vs. the lowest quarter of chronic stress; aRR: 1.4 (1.0,2.0) for possible anxiety symptoms vs. no symptoms). No relationship was found between stress or related constructs and AD diagnoses nor could we show consistent associations between maternal HCC and child AD. However, a higher RR of child AD was evident in families not yet affected by AD in siblings given maternal depressive symptoms, examined in the crude model.

CONCLUSIONS

Stress measurements or related constructs are linked to AD symptoms, but association with AD diagnoses is limited. The reason for this divergence still needs further research.

In 6- to 8-year-old children, hair cortisol is associated with body mass index and somatic complaints, but not with stress, health-related quality of life, blood pressure, retinal vessel diameters, and cardiorespiratory fitness

OBJECTIVES

Hair cortisol measurement has become an increasingly accepted approach in endocrinology and biopsychology. However, while in adult research hair cortisol has been proposed as a relevant biomarker for chronic stress (and its adverse consequences), studies with children are scarce. Therefore, the goal of the present exploratory study was to examine the associations between hair cortisol concentrations (HCCs), stress, and a series of health-related outcomes in a sample of Swiss first grade schoolchildren.

METHODS

The sample consisted of 318 children (53% girls, M_age=7.26, SD=0.35). Hair strands were taken near the scalp from a posterior vertex position, and HCCs were tested for the first 3-cm hair segment. Parents provided information about their children's age, gender, parental education, children's stress (recent critical life events, daily hassles), health-related quality of life, and psychosomatic complaints. Body composition, blood pressure, retinal vessel diameters, and cardiorespiratory fitness were measured with established methods.

RESULTS

In multiple regression analyses, higher HCCs were weakly associated with increased BMI in girls (β=0.22, p<0.001), whereas higher HCCs were associated with increased somatic complaints in boys (β=0.20, p<0.05). No significant relationships were found between HCCs and parental reports of stress, health-related quality of life, blood pressure, retinal vessel diameters, and cardiorespiratory fitness.

CONCLUSIONS

Although small significant relationships were found between HCCs, BMI and somatic complaints, the findings of this exploratory study challenge the view that HCCs can be used as a reliable biomarker of recent critical life events, daily hassles, health-related quality of life, and cardiovascular health indicators in non-clinical young children.

Assessing significant (>30%) alopecia as a possible biomarker for stress in captive rhesus monkeys (Macaca mulatta)

Hair loss is common in macaque colonies. Very little is known about the relationship between psychological stress and hair loss. We initially examined alopecia and hair cortisol concentrations in 198 (89 male) rhesus macaques from three primate centers and demonstrated replicability of our previous finding that extensive alopecia (>30% hair loss) is associated with increased chronic cortisol concentrations and significantly affected by facility. A subset of these monkeys (142 of which 67 were males) were sampled twice approximately 8 months apart allowing us to examine the hypotheses that gaining hair should be associated with decreases in cortisol concentrations and vice versa. Hair loss was digitally scored using ImageJ software for the first sample. Then visual assessment was used to examine the second sample, resulting in three categories of coat condition: (i) monkeys that remained fully haired; (ii) monkeys that remained alopecic (with more than 30% hair loss); or (iii) monkeys that showed more than a 15% increase in hair. The sample size for the group that lost hair was too small to be analyzed. Consistent with our hypothesis, monkeys that gained hair showed a significant reduction in hair cortisol concentrations but this effect only held for females. Coat condition changed little across sampling periods with only 25 (11 male) monkeys showing a greater than 15% gain of hair. Twenty (7 male) monkeys remained alopecic, whereas 97 (49 males) remained fully haired. Hair cortisol was highly correlated across samples for the monkeys that retained their status (remained alopecic or retained their hair). Am. J. Primatol. 79:e22547, 2017. © 2016 Wiley Periodicals, Inc.

Hair cortisol and its potential value as a physiological measure of stress response in human and non-human animals

There is considerable interest in the potential for measuring cortisol in hair as a means of quantifying stress responses in human and non-human animals. This review updates the rapid advancement in our knowledge of hair cortisol, methods for its measurement, its relationship to acute and chronic stress, and its repeatability and heritability. The advantages of measuring cortisol in hair compared with other matrices such as blood, saliva and excreta and the current theories of the mechanisms of cortisol incorporation into the fibre are described. Hair cortisol as a measure of the physiological response to stress in a variety of species is presented, including correlations with other sample matrices, the relationship between hair cortisol and psychosocial stress and the repeatability and heritability of hair cortisol concentrations. Current standards for the quantification of hair cortisol are critically reviewed in detail for the first time and gaps in technical validation of these methods highlighted. The known effects of a variety of sources of hair cortisol variation are also reviewed, including hair sampling site, sex, age and adiposity. There is currently insufficient evidence to conclude that cortisol concentration in hair accurately reflects long-term blood cortisol concentrations. Similarly, there is a lack of information surrounding the mechanisms of cortisol incorporation into the hair. This review highlights several directions for future research to more fully validate the use of hair cortisol as an indicator of chronic stress.

Assessing cortisol from hair samples in a large observational cohort: The Whitehall II study

Hair cortisol concentrations (HCC) have been suggested to reflect long-term integrated cortisol levels, but most evidence of associations with co-variates is from small samples of healthy volunteers. The objective of this study was to describe the collection of hair samples in a large cohort study and report associations of demographic and health measures with HCC. We examined HCC measured from the 3cm hair segment near the scalp in 3507 participants (aged 59-83y) from The Whitehall II occupational cohort study of British civil servants. Hair samples were analysed using a column switching LC-APCI-MS/MS assay. Findings from mutually adjusted linear regression analyses revealed lower HCC in participants who reported use of hair dye [% difference (95%CI); -12.5 (-22.0, -1.9), p value=0.022] and evidence suggestive of differences by length of sample storage and seasonal variation. With regard to demographic variables, HCC was lower in women compared to men [-17.0 (-24.8, -8.4), p value <0.001] and higher in Black compared to other ethnic groups. Prevalent diabetes, use of systemic corticosteroids and cardiovascular medication were independently associated with higher HCC. With regard to health, depressive symptoms were associated with higher HCC [20.0 (8.1, 33.3), p value=0.001] following adjustment for physical disease and medication. We conclude that hair steroid analysis presents significant opportunities for assessing cortisol in large scale cohorts. Demographic factors, sample storage, season of collection and hair characteristics should be considered in future analyses. Health status, both mental and physical, is linked to HCC.

Hair cortisol concentration and glycated hemoglobin in African American adults

BACKGROUND

African Americans have higher diabetes prevalence compared to Whites. They also have elevated cortisol levels - indicating possible HPA axis dysregulation - which may raise blood glucose as part of the biological response to physiological and psychosocial stress. Little is known about chronic cortisol levels in African Americans, and even less about the role of chronically elevated cortisol in type 2 diabetes development in this racial group.

PURPOSE

We used analysis of cortisol in hair to examine associations of long-term (∼3months) cortisol levels with glycated hemoglobin (HbA1c) in a group of African American adults. In exploratory analyses, we also studied the relationship of hair dehydroepiandrosterone (DHEA) with HbA1c.

METHOD

Participants were 61 community-dwelling African American adults (85% female; mean age 54.30 years). The first 3cm of scalp-near hair were analyzed for cortisol and DHEA concentration using enzyme-linked immunoassay analysis. Glycated hemoglobin was assessed, and regression analyses predicting HbA1c from hair cortisol and DHEA were performed in the full sample and in a subsample of participants (n=20) meeting the National Institute of Diabetes and Digestive Kidney Disease (NIDDK) criteria for type 2 diabetes (HbA1c≥6.5%).

RESULTS

In the full sample, HbA1c increased with hair cortisol level (β=0.22, p=0.04, f(2)=0.10), independent of age, sex, chronic health conditions, diabetes medication use, exercise, and depressive symptoms. In the subsample of participants with an HbA1c≥6.5%, hair cortisol was also positively related to HbA1c (β=0.45, p=0.04, f(2)=0.32), independent of diabetes medication use. Glycated hemoglobin was unrelated to hair DHEA in both the full sample and HbA1c≥6.5% subsample.

CONCLUSION

Long-term HPA axis dysregulation in the form of elevated hair cortisol is associated with elevated HbA1c in African American adults.

Association between Hair Cortisol Concentration and Adiposity Measures among Children and Parents from the "Healthy Start" Study

Background

Previous studies have suggested a direct association between hair cortisol concentration (HCC) and Body Mass Index (BMI), as well as other adiposity measures. However, these studies have mostly been conducted among adult populations.

Objective

To examine the association between HCC and different measures of adiposity among a selected group of children predisposed to obesity and their parents.

Methods

We conducted a cross-sectional study based on 363 children and their parents (301 mothers and 231 fathers) participating in the “Healthy Start” study. Linear regression analysis was used to investigate associations between HCC and adiposity measures while taking into account possible confounding factors. Analyses were performed examining the association between HCC and BMI, fat mass and fat free mass index Z-scores, as well as waist circumference and waist-hip ratio among the children. Likewise, the association between HCC and BMI among the parents was explored. Finally, we examined the association between parental HCC and children’s adiposity measures.

Results

HCC was directly associated with a higher BMI among the fathers (0.49 kg/m² [95% CI: 0.09, 0.90, P = 0.02] per 100 pg/mg) and the mothers (0.93 kg/m² [95% CI: 0.24, 1.61, P = 0.01] per 100 pg/mg). We found no clear evidence of an association between HCC and adiposity measures among children. However, a high maternal HCC was associated with a high fat mass index and low fat free mass index z-score in the offspring (0.14 SD [95% CI: 0.02, 0.26, P = 0.02] and -0.17 SD [95% CI: -0.30, -0.05, P = 0.01] per 100 pg/mg, respectively).

Conclusions

Our study found no evidence of an association between HCC and measures of adiposity among children predisposed to obesity. However, HCC may be directly associated with BMI among men and women, and maternal HCC may be related to a higher fat mass and a lower fat free mass among their children.

Correspondence between hair cortisol concentrations and 30-day integrated daily salivary and weekly urinary cortisol measures

Characterization of cortisol production, regulation and function is of considerable interest and relevance given its ubiquitous role in virtually all aspects of physiology, health and disease risk. The quantification of cortisol concentration in hair has been proposed as a promising approach for the retrospective assessment of integrated, long-term cortisol production. However, human research is still needed to directly test and validate current assumptions about which aspects of cortisol production and regulation are reflected in hair cortisol concentrations (HCC). Here, we report findings from a validation study in a sample of 17 healthy adults (mean±SD age: 34±8.6 yrs). To determine the extent to which HCC captures cumulative cortisol production, we examined the correspondence of HCC, obtained from the first 1cm scalp-near hair segment, assumed to retrospectively reflect 1-month integrated cortisol secretion, with 30-day average salivary cortisol area-under-the curve (AUC) based on 3 samples collected per day (on awakening, +30min, at bedtime) and the average of 4 weekly 24-h urinary free cortisol (UFC) assessments. To further address which aspects of cortisol production and regulation are best reflected in the HCC measure, we also examined components of the salivary measures that represent: (1) production in response to the challenge of awakening (using the cortisol awakening response [CAR]), and (2) chronobiological regulation of cortisol production (using diurnal slope). Finally, we evaluated the test-retest stability of each cortisol measure. Results indicate that HCC was most strongly associated with the prior 30-day integrated cortisol production measure (average salivary cortisol AUC) (r=0.61, p=0.01). There were no significant associations between HCC and the 30-day summary measures using CAR or diurnal slope. The relationship between 1-month integrated 24-h UFC and HCC did not reach statistical significance (r=0.30, p=0.28). Lastly, of all cortisol measures, test-retest correlations of serial measures were highest for HCC (month-to-month: r=0.84, p<0.001), followed by 24-h UFC (week-to-week: r's between 0.59 and 0.68, ps<0.05) and then integrated salivary cortisol concentrations (week-to-week: r's between 0.38 and 0.61, p's between 0.13 and 0.01). These findings support the contention that HCC provides a reliable estimate of long-term integrated free cortisol production that is aligned with integrated salivary cortisol production measured over a corresponding one-month period.

LC-MS based analysis of endogenous steroid hormones in human hair

The quantification of endogenous steroid hormone concentrations in hair is increasingly used as a method for obtaining retrospective information on long-term integrated hormone exposure. Several different analytical procedures have been employed for hair steroid analysis, with liquid chromatography-mass spectrometry (LC-MS) being recognized as a particularly powerful analytical tool. Several methodological aspects affect the performance of LC-MS systems for hair steroid analysis, including sample preparation and pretreatment, steroid extraction, post-incubation purification, LC methodology, ionization techniques and MS specifications. Here, we critically review the differential value of such protocol variants for hair steroid hormones analysis, focusing on both analytical quality and practical feasibility issues. Our results show that, when methodological challenges are adequately addressed, LC-MS protocols can not only yield excellent sensitivity and specificity but are also characterized by relatively simple sample processing and short run times. This makes LC-MS based hair steroid protocols particularly suitable as a high-quality option for routine application in research contexts requiring the processing of larger numbers of samples.

GENDER DETERMINES SERUM FREE CORTISOL: HIGHER LEVELS IN MEN

OBJECTIVE

Because only the free fraction of serum cortisol can readily access glucocorticoid receptors, we investigated whether or not a gender-related difference in serum free cortisol (FC) exists in the basal and adrenocorticotropic hormone (ACTH)-stimulated state.

METHODS

Serum total cortisol (TC) and FC were measured in 323 subjects (175 men; 148 women). Additionally, the low-dose 1-μg ACTH test was performed in 56 subjects (30 women, 26 men). Subjects were healthy volunteers, recruited in a preventive medicine screening program and an outpatient clinic.

RESULTS

Overall, basal serum TC and FC level were ~18 and ~33%, respectively, higher in men than in women (TC, 14.5 ± 0.33 μg/dL vs. 12.3 ± 0.33 μg/dL; P<.0001; FC, 0.68 ± 0.02 μg/dL vs. 0.51 ± 0.02 μg/dL; P<.0001). The higher FC in men relative to women was apparent across a wide age range (17 to 86 years) and persisted after adjustment for age and body mass index. The FC fraction (%FC, out of TC) was concordantly higher in men (5.4 ± 0.09% vs. 4.8 ± 0.3%; P = .046). FC was not related to the estimated menopausal status (women age below and above 47, 50, or 53 years). ACTH-stimulated FC levels were significantly higher in men compared to women, as reflected by the area under the response curve (49.4 ± 3.4 μg × min vs. 39.6 ± 2.2 μg × min; P = .0014).

CONCLUSION

Gender is an unrecognized determinant of serum FC in humans. The possibility of lifelong exposure to the higher bioactive fraction of cortisol under basal conditions or daily stress involving ACTH stimulation should be further investigated in the context of gender-related phenotypic features such as "android" (visceral) fat deposition and longevity.

ABBREVIATIONS

ACTH = adrenocorticotropic hormone BMI = body mass index CBG = cortisol-binding globulin FC = free cortisol HPA = hypothalamic-pituitary-adrenal TC = total cortisol.

Hair cortisol as a hypothalamic-pituitary-adrenal axis biomarker in pregnant women with asthma: a retrospective observational study

Background

Cortisol is a hormone involved in many physiological functions including fetal maturation and epigenetic programming during pregnancy. This study aimed to use hair cortisol as a biomarker of chronic inhaled corticosteroid (ICS) exposure and assess the potential effects of asthma on the hypothalamic-pituitary-adrenal (HPA) axis in pregnant women. We hypothesized that pregnant women with asthma treated with ICS would exhibit lower hair cortisol concentrations, indicative of adrenal suppression, compared to women with asthma not using ICS and women who do not have asthma.

Methods

We performed an observational retrospective cohort study. Hair samples were analyzed from pregnant women with asthma, with (n = 56) and without (n = 31) ICS treatment, and pregnant women without asthma (n = 31). Hair samples were segmented based on the growth rate of 1 cm/month and analyzed by enzyme immunoassay to provide cortisol concentrations corresponding to preconception, trimesters 1–3, and postpartum. Hair cortisol concentrations were compared within and among the groups using non-parametric statistical tests.

Results

Hair cortisol concentrations increased across trimesters for all three groups, but this increase was dampened in women with asthma (P = 0.03 for Controls vs. ICS Treated and Controls vs. No ICS). ICS Treated women taking more than five doses per week had hair cortisol concentrations 47 % lower in third trimester than Controls. Linear regression of the third trimester hair cortisol results identified asthma as a significant factor when comparing consistent ICS use or asthma as the predictor (F_{(1, 25)} = 9.7, P = 0.005, R²_adj = 0.257).

Conclusions

Hair cortisol successfully showed the expected change in cortisol over the course of pregnancy and may be a useful biomarker of HPA axis function in pregnant women with asthma. The potential impact of decreased maternal cortisol in women with asthma on perinatal outcomes remains to be determined.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-016-0962-4) contains supplementary material, which is available to authorized users.

An integrative model linking traumatization, cortisol dysregulation and posttraumatic stress disorder: Insight from recent hair cortisol findings

Abundant evidence suggests links between trauma exposure, altered secretion of the glucocorticoid cortisol and the development/maintenance of posttraumatic stress disorder (PTSD), albeit with some inconsistency in findings. Further insight into the complex relations underlying this process may be derived from an increasing number of studies using hair cortisol analysis, a novel assessment strategy assumed to retrospectively capture long-term integrated cortisol secretion. Here, we evaluate the utility of hair cortisol analysis as a method in trauma/PTSD research and review current findings in this context. We compare hair cortisol data on the complex links between trauma, cortisol dysregulation and PTSD against the main findings obtained using traditional cortisol assessment methods. Finally, we integrate these data into a model which proposes that traumatization leads to dose and time-dependent changes in long-term cortisol output (initial post-traumatic increase, subsequent chronic attenuation) and that such dysregulation may partly mediate the link between traumatic load and the risk of PTSD development upon additional trauma exposure ("building block effect").

Corticosterone dysregulation exacerbates disease progression in the R6/2 transgenic mouse model of Huntington's disease

Huntington's disease (HD) is a genetic neurological disorder that causes severe and progressive motor, cognitive, psychiatric, and metabolic symptoms. There is a robust, significant elevation in circulating levels of the stress hormone, cortisol, in HD patients; however, the causes and consequences of this elevation are largely uncharacterized. Here, we evaluated whether elevated levels of corticosterone, the rodent homolog of cortisol, contributed to the development of symptomology in transgenic HD mice. Wild-type (WT) and transgenic R6/2 mice were given either 1) adrenalectomy with WT-level corticosterone replacement (10ng/ml), 2) adrenalectomy with high HD-level corticosterone replacement (60ng/ml), or 3) sham surgery without replacement. R6/2 mice on HD-level replacement showed severe and rapid weight loss (p<0.05) and a shorter latency to death (p<0.01) relative to the HD mice on WT-level replacement. We further evaluated basal and stress-induced levels of circulating corticosterone in R6/2 mice throughout the course of their life. We found that R6/2 transgenic HD mice display a spontaneous elevation in circulating corticosterone levels that became significant at 10weeks of age. Furthermore, we identified significant dysregulation of circadian rhythmicity of corticosterone release measured over a 24h period compared to wild-type controls. Unexpectedly, we found that R6/2 transgenic mice show a blunted corticosterone response to restraint stress, compared to wild-type mice. Together, these data provide further evidence that HPA-axis activity is abnormal in R6/2 mice, and highlight the important role that cortisol plays in HD symptom development. Our findings suggest that cortisol-reducing therapeutics may be of value in improving HD patient quality of life.

Influence of external factors on hair cortisol concentrations

Measuring hair cortisol has attracted interest as a long term parameter for chronic stress evaluation. However, some studies support the hypothesis that locally produced cortisol, originating from the hair follicle or skin cells, affects concentrations in the hair. In an animal model the influence of different treatments (extensive brushing, administration of a hyperemising fluid that enhances blood circulation or a synthetic glucocorticoid) on the local cortisol production of hair was evaluated. Therefore eight sheep were sheared and the area of the skin surface of the back was quartered, with three quarters being daily subjected to a certain treatment and one quarter remaining untreated. The skin areas were sheared again after three weeks and cortisol concentrations of all wool samples were determined by immunoassay. Systemic cortisol concentrations were additionally monitored with faecal samples, indicating a significant decline in concentrations of glucocorticoid metabolites between week 1 and 2 or 3, respectively. We found no significant difference in hair cortisol concentrations between fields before treatment (p=0.310). Comparing matched fields before and after treatment, we found no significant differences in wool cortisol concentrations for fields treated with hyperemising fluid as well as for the control fields (p=0.329, p=0.097). Hairs exposed to either extensive brushing or dexamethasone fluid had significantly higher immunoreactive cortisol concentrations after three weeks of treatment (p=0.016, p=0.01). We therefore advise cautious interpretation when measuring hair cortisol concentrations as a parameter for chronic stress, because external factors may have a significant influence on the results.

Pilot study of adrenal steroid hormones in hair as an indicator of chronic mental and physical stress

Currently, the quantitative analysis of moderators affecting the function of the hypothalamus-pituitary-adrenal (HPA)-axis in health and sickness is still unreliable. This is, in particular, due to physiological factors such as pulsatile ultradian and circadian glucocorticoid secretion as well as to methodological limitations of the current techniques for steroid hormone determination. Based on this background, the determination of long-term hair steroid concentrations is an important methodological improvement allowing for the quantitative analysis of chronic HPA axis-activation. In order to determine the relationship between chronic mental and physical stress and a chronic activation of the HPA axis, we performed a cross-sectional pilot-study with 40 healthy students and examined the relationships between physical activity, mental burden(s), subjective stress perceptions, depressiveness, anxiety, physical complaints, sense of coherence, resilience, and the long-term integrated steroid hormone levels in hair. The results showed that the concentrations of cortisol, cortisone, and dehydroepiandrosterone in hair were significantly correlated to mental (p = 0.034) and physical stress (p = 0.001) as well as to subjective stress perception (p = 0.006). We conclude that steroid concentrations in hair are decisive predictors for an increase in the long-term-HPA axis activity. Moreover, this biomarker is suitable for capturing the stresslevel after burdening events and physical activity.

The Association of Hair Cortisol with Self-Reported Chronic Psychosocial Stress and Symptoms of Anxiety and Depression in Women Shortly after Delivery

BACKGROUND

Psychosocial stress during pregnancy including anxiety and depression is known to have adverse health effects on newborns. However, measuring these psychological constructs is complex with psychological, endocrinological, and physiological systems being affected. Hair cortisol concentrations (HCC), assumed to reflect long-term endocrine consequences of stress exposure, represent a promising instrument for epidemiological research. However, the association between HCC and questionnaire-based instruments is unclear.

METHODS

In the Ulm SPATZ Health Study, mothers were recruited shortly after delivery in the University Medical Centre Ulm, Germany between April 2012 and May 2013. HCC of 768 participants were determined in scalp-near 3 cm maternal hair segments, assumed to reflect cortisol exposure over the last trimester of pregnancy. Chronic stress, anxiety, and depressive symptomatology were self-reported in questionnaire-based instruments. Spearman correlation coefficients between HCC and these instruments as well as means of HCC in highly and low stressed subgroups were calculated.

RESULTS

HCC were not correlated with self-reported chronic stress, anxiety, or depressive symptomatology. Furthermore, the investigation of sub-populations did not reveal substantial differences of HCC across highly and low stressed women.

CONCLUSIONS

HCC were not found to correlate with self-reports of chronic stress, anxiety, or depressive symptomatology. Among other things, these findings could reflect problems with questionnaire-based assessments obtained shortly after delivery such as recall bias and/or suggest that associations between cortisol secretion and psychosocial stress are difficult to detect due to, e.g. a strong physiological increase of cortisol in the last trimester.

Sources of variation in hair cortisol in wild and captive non-human primates

Hair cortisol analysis is a potentially powerful tool for evaluating adrenal function and chronic stress. However, the technique has only recently been applied widely to studies of wildlife, including primates, and there are numerous practical and technical factors that should be considered to ensure good quality data and the validity of results and conclusions. Here we report on various intrinsic and extrinsic sources of variation in hair cortisol measurements in wild and captive primates. Hair samples from both wild and captive primates revealed that age and sex can affect hair cortisol concentrations; these effects need to be controlled for when making comparisons between individual animals or populations. Hair growth rates also showed considerable inter-specific variation among a number of primate species. We describe technical limitations of hair analyses and variation in cortisol concentrations as a function of asynchronous hair growth, anatomical site of collection, and the amount and numbers of hair/s used for cortisol extraction. We discuss these sources of variation and their implications for proper study design and interpretation of results.

The lifetime experience of traumatic events is associated with hair cortisol concentrations in community-based children

Adversity early in life can disrupt the functioning of the hypothalamic-pituitary-adrenal axis (HPAA) and increase risk for negative health outcomes. Recent research suggests that cortisol in scalp hair represents a promising measure of HPAA function. However, little is known about the relationship between early exposure to traumatic events and hair cortisol concentrations (HCC) in childhood, a critical period of HPAA development. The current study measured HCC in scalp hair samples collected from 70 community-based children (14 males, mean age=9.50) participating in the Imaging Brain Development in the Childhood to Adolescence Transition Study (iCATS). Data were also collected on lifetime exposure to traumatic events and current depressive symptoms. Lifetime exposure to trauma was associated with elevated HCC; however, HCC was not associated with current depressive symptoms. Consistent with some prior work, males were found to have higher HCC than females, although results should be treated with caution due to the small number of males who took part. Our findings suggest that hair cortisol may represent a biomarker of exposure to trauma in this age group; however, further study is necessary with a particular focus on the characterization of trauma and other forms of adversity.

Hair cortisol and self-reported stress in healthy, working adults

Chronic stress can be important in the pathology of chronic disease. Hair cortisol concentrations (HCC) are proposed to reflect long term cortisol secretion from exposure to stress. To date, inconsistencies in the relationship between HCC and self-reported stress have been attributed to variation and limitations of perceived stress measurement. We report data from employees of two large public sector worksites (n=132). Socio-demographic, health, lifestyle, perceived stress scale (PSS), and work-related effort reward imbalance (ERI) were collected at baseline. Participants were asked to respond to mobile text messages every two days, asking them to report current stress levels (Ecological momentary assessment, EMA), and mean stress was determined overall, during work hours, and out of work hours. At 12 weeks, the appraisal of stressful life events scale (ALES) was completed and 3 cm scalp hair samples were taken, from which HCC was determined (to reflect cortisol secretion over the past 12 weeks). Mean response rate to EMA was 81.9 ± 14.9%. Associations between HCC and the various self-reported stress measures (adjusted for use of hair dye) were weak (all<.3). We observed significant associations with HCC for EMA measured stress responses received out of work hours (ρ=.196, p=.013) and ALES Loss subscale (ρ=.241, p=.003), and two individual items from ERI (relating to future work situation). In regression analysis adjusting for other possible confounders, only the HCC-ALES Loss association remained significant (p=.011). Overall, our study confirms that EMA provides a useful measurement tool that can gather perceived stress measures in real-time. But, there was no relationship between self-reported stress collected in this way, and HCC. The modest association between HCC and stress appraisal does however, provide some evidence for the role of cognitive processes in chronic stress.

Hair cortisol levels, perceived stress and body mass index in women and children living in socioeconomically disadvantaged neighborhoods: the READI study

Disadvantaged communities provide adverse psychosocial exposures that have been linked to high levels of stress, and this may provide one explanatory pathway linking socioeconomic disadvantage to obesity. This study used hair cortisol analysis to quantify associations between stress and body mass index (BMI), and between hair cortisol and perceived psychological stress levels, in women and children living in socioeconomically disadvantaged neighborhoods. Participants were a volunteer sample of 70 women from the Resilience for Eating and Activity Despite Inequality study, including 30 maternal-child pairs. Women self-reported body weight, height and perceived psychological stress using the Perceived Stress Scale (PSS), and provided hair samples for themselves and their child. Children's body weight and height were measured. Following extraction, hair cortisol levels were measured using enzyme-linked immunosorbent assay. Multiple linear regression models examined associations between stress and BMI, and between hair cortisol and perceived stress levels in women and children. Women's hair cortisol levels were not associated with their BMI or PSS scores. Women's PSS scores were positively associated with their BMI (p = 0.015). Within maternal-child pairs, mothers and children's hair cortisol levels were strongly positively associated (p = 0.006). Maternal hair cortisol levels and PSS scores were unrelated to their child's zBMI. Children's hair cortisol levels were not associated with their zBMI or with their mother's PSS score. Findings suggest that cortisol-based and perceived psychological measures of stress may be distinct among women and children living in disadvantaged neighborhoods. Perceived psychological measures may be more important predictors of weight-related risk.

The relationship between cortisol, stress and psychiatric illness: New insights using hair analysis

BACKGROUND

Stress is an established important contributor to the development of mental illness and stress related disorders. The biology implicated in the homeostasis of pathological stress mechanisms is not fully established. One of the difficulties with current techniques is the limitation in capturing chronic levels of cortisol as an expression of stress levels in humans. Hair samples can be used to evaluate cortisol levels averaged over relatively long periods of time, therefore providing a more valid measure of chronic levels of this hormone. A highly replicable technique to measure long-term cortisol could prove pivotal in improving our understanding of the role of stress in psychiatric disorders.

METHODS

This review synthesises all the published studies relating hair cortisol concentration (HCC) to stress and to psychiatric disorders. It describes and summarises their findings with the aim of providing a summary picture of the current state of this line of research.

RESULTS

The strongest finding to date is the replicable increases in hair cortisol associated with stressful life events. Findings in psychiatric disorders are more sparse and inconsistent. There is some support for the presence of raised HCC in major depressive disorders, and for lowered HCC in posttraumatic stress disorder, suggesting chronic hypercortisolaemia and hypocortisolaemia respectively.

CONCLUSIONS

HCC is a promising methodology to study chronic cortisol levels with the potential to help characterise psychiatric and stress related disorders. The combination of chronic and acute cortisol measurements has the potential for more accurately determining different aspects of the stress response, and ultimately for the development of a biological marker to aid diagnosis and response to treatment.

Effects of body region and time on hair cortisol concentrations in chimpanzees (Pan troglodytes)

Hair cortisol concentrations (HCC) are increasingly recognized as an integrated measure of the systemic cortisol secretion. Yet, we still know very little about confounding effects on HCC in animals. The present study therefore used hair from semi-wild and zoo living chimpanzees to investigate (1) intra-individual variability of HCC (body-region effect), and (2) the stability of HCC along the hair shaft (traditionally called the washout effect). Our results indicate that absolute HCC varied substantially between certain body regions, but a factor analysis revealed that these HCC differences were mainly attributable to one common source of variance. Thus, hair from all body regions provides similar biological signals and can be mixed, albeit at the cost of a lower signal-to-noise ratio. With regard to potential underlying mechanisms, we studied skin blood flow, as observed through thermal images from one chimpanzee. We found the general HCC pattern was reflected in differences in surface body temperature observed in this individual in three out of four body regions. In a separate set of samples, we found first evidence to suggest that the systematic cortisol decrease along the hair shaft, as observed in humans, is also present in chimpanzee hair. The effect was more pronounced in semi-wild than in zoo chimpanzees presumably due to more exposure to ambient weather conditions.

Clinical applications of cortisol measurements in hair

Cortisol measurements in blood, saliva and urine are frequently used to examine the hypothalamus-pituitary-adrenal (HPA) axis in clinical practice and in research. However, cortisol levels are subject to variations due to acute stress, the diurnal rhythm and pulsatile secretion. Cortisol measurements in body fluids are not always a reflection of long-term cortisol exposure. The analysis of cortisol in scalp hair is a relatively novel method to measure cumulative cortisol exposure over months up to years. Over the past years, hair cortisol concentrations (HCC) have been examined in association with a large number of somatic and mental health conditions. HCC can be used to evaluate disturbances of the HPA axis, including Cushing's syndrome, and to evaluate hydrocortisone treatment. Using HCC, retrospective timelines of cortisol exposure can be created which can be of value in diagnosing cyclic hypercortisolism. HCC have also been shown to increase with psychological stressors, including major life events, as well as physical stressors, such as endurance exercise and shift work. Initial studies show that HCC may be increased in depression, but decreased in general anxiety disorder. In posttraumatic stress disorder, changes in HCC seem to be dependent on the type of traumatic experience and the time since traumatization. Increased hair cortisol is consistently linked to obesity, metabolic syndrome and cardiovascular disease. Potentially, HCC could form a future marker for cardiovascular risk stratification, as well as serve as a treatment target.

Hair cortisol as a novel biomarker of HPA suppression by inhaled corticosteroids in children

BACKGROUND

Asthma is the most common chronic condition in childhood, and the recommended pharmacotherapy for long-term control includes the use of inhaled corticosteroids (ICS). ICS were designed to act at the site of inflammation in the lung, thus decreasing systemic absorption and reducing the risk of adverse effects associated with corticosteroid use (e.g., HPA suppression and its consequent effects). Available data show that measurement of hair cortisol successfully reflects endogenous cortisol levels. We sought to examine whether hair cortisol measurements can be used to identify HPA suppression surrounding ICS therapy in children with asthma.

METHODS

Hair samples were collected from the vertex posterior region of the head of 18 asthmatic children. We compared their hair cortisol concentration during ICS use with the concentration prior to ICS use.

RESULTS

During ICS therapy, median hair cortisol levels were twofold lower compared with the period of no ICS use (median 89.8 ng/g vs. 198.2 ng/g, P = 0.0015).

CONCLUSION

Hair cortisol is an effective biomarker of the HPA suppression associated with ICS therapy and can be a sensitive tool for determining systemic effects of ICS use and monitoring adherence. Future research is needed to characterize the effect of untreated asthma on hair cortisol concentrations, if any.

Analyzing pathways from childhood maltreatment to internalizing symptoms and disorders in children and adolescents (AMIS): a study protocol

BACKGROUND

Effective interventions for maltreated children are impeded by gaps in our knowledge of the etiopathogenic mechanisms leading from maltreatment to mental disorders. Although some studies have already identified individual risk factors, there is a lack of large-scale multilevel research on how psychosocial, neurobiological, and genetic factors act in concert to modulate risk of internalizing psychopathology in childhood following maltreatment. To help close this gap, we aim to delineate gender-specific pathways from maltreatment to psychological disorder/resilience. To this end, we examine the interplay of specific maltreatment characteristics and psychological, endocrine, metabolomic, and (epi-)genomic stress response patterns as well as cognitive-emotional/social processes as determinants of developmental outcome. Specifically, we will explore endocrine, metabolomic, and epigenetic mechanisms leading from maltreatment to a higher risk of depression and anxiety disorders.

METHODS/DESIGN

Four large samples amounting to a total of N = 920 children aged 4-16 years will be assessed: Two cohorts with prior internalizing psychopathology and controls will be checked for maltreatment and two cohorts with substantiated maltreatment will be checked for internalizing (and externalizing) psychopathology. We will apply a multi-source (interview, questionnaires, official records), multi-informant strategy (parents, children, teachers) to assess maltreatment characteristics (e.g., subtypes, developmental timing, chronicity) and psychopathological symptoms, supplemented with multiple measurements of risk and protective factors and cutting-edge laboratory analyses of endocrine, steroid metabolomic and epigenetic factors. As previous assessments in the two largest samples are already available, longitudinal data will be generated within the three year study period.

DISCUSSION

Our results will lay the empirical foundation for (a) detection of early biopsychosocial markers, (b) development of screening measures, and

Hair Cortisol Analysis: A Promising Biomarker of HPA Activation in Older Adults

Prolonged stress is a potentially harmful and often undetected risk factor for chronic illness in older adults. Cortisol, one indicator of the body's hormonal responses to stress, is regulated by the hypothalamic-pituitary-adrenal (HPA) axis and is commonly measured in saliva, urine, or blood samples. Cortisol possesses a diurnal pattern and thus collection timing is critical. Hair cortisol is a proxy measure to the total retrospective activity of the HPA axis over the preceding months, much like hemoglobin A1c is a proxy measure of glucose control over the past 3 months. The aim of this review is to examine a novel biomarker, hair cortisol, as a practical measure of long-term retrospective cortisol activity associated with chronic stress in older adults. Hair cortisol analysis advances the science of aging by better characterizing chronic stress as a risk factor for chronic illness progression and as a biomarker of the effectiveness of stress reduction interventions.

Coat and claws as new matrices for noninvasive long-term cortisol assessment in dogs from birth up to 30 days of age

The last stage of fetal development and the neonatal period represent the most critical phases for the mammals' offspring. In the dog, the knowledge about the final intrauterine fetal development and biology, as well as about the neonatal physiology, remains scarce. Hormonal changes occurring in the last intrauterine fetal phase and during the early neonatal age are still not completely clear, probably because of the invasiveness related to the collection of the more common biological matrix, represented by circulating blood. Toward term of pregnancy, during parturition, and after birth, the hypothalamic-pituitary-adrenal axis is a key system regulating several physiological processes, and its activity was previously investigated by blood analysis, considered an invasive procedure providing a single-point measurement. In respect to animal welfare, and for a more correct long-term retrospective investigation, noninvasive hormonal studies were performed firstly on the hair of humans and coat of animals and, more recently, in the nails of human beings. This study was aimed to assess cortisol (COR) in coat and claws of newborn puppies and to evaluate the possible influence of the newborn gender, breed body size, and age on coat and claws COR concentrations. The results obtained from 165 newborn puppies evidenced that coat and claws COR levels were highly correlated each other (P < 0.0001), although the COR accumulation in the two matrices was different in relation to the class of age. Moreover, the puppies age influenced both coat and claws COR concentrations (P < 0.05), with premature puppies showing higher values when compared to term born-dead puppies or puppies dead between 1 and 30 days of age. The present study reported that COR is quantifiable in coat and claws of newborn dogs. Moreover, both matrices appear as useful tools for new, noninvasive, long-term perinatal and neonatal researches also in canine species.

Sweat-inducing physiological challenges do not result in acute changes in hair cortisol concentrations

Hair cortisol concentrations (HCC) are assumed to provide a stable, integrative marker of long-term systemic cortisol secretion. However, contrary to this assumption, some recent observations have raised the possibility that HCC may be subject to acute influences, potentially related to cortisol incorporation from sweat. Here, we provide a first detailed in vivo investigation of this possibility comprising two independent experimental studies: study I (N=42) used a treadmill challenge to induce sweating together with systemic cortisol reactivity while in study II (N=52) a sauna bathing challenge induced sweating without systemic cortisol changes. In both studies, repeated assessments of HCC, salivary cortisol, cortisol in sweat and individuals' sweating rate (single assessment) were conducted on the experimental day and at a next-day follow-up. Results across the two studies consistently revealed that HCC were not altered by the acute interventions. Further, HCC were found to be unrelated to acute salivary cortisol reactivity, sweat cortisol levels, sweating rate or the time of examination. In line with previous data, cortisol levels in sweat were strongly related to total salivary cortisol output across the examined periods. The present results oppose recent case report data by showing that single sweat-inducing interventions do not result in acute changes in HCC. Our data also tentatively speak against the notion that cortisol in sweat may be a dominant source of HCC. Further, our findings also indicate that HCC are not subject to diurnal variation. This research provides further support for hair cortisol analysis as a marker of integrated long-term systemic cortisol secretion.