Human hair cortisol concentration (HCC) has previously been found to be highly stable for a 1-year interval (r = 0.73) in terms of a product-moment correlation. The present study aimed to replicate this finding and compare HCC stability regarding 1-year and 2-year test-retest intervals. Female university students (N = 39) provided hair strands twice (t1 and t2) at intervals of 1 (n = 21) or 2 years (n = 18). Multiple regression analysis predicting HCC at t2 revealed a significant interaction term (HCC at t1 × time interval condition). It was determined that HCCs were substantially related for the 1-year interval but unrelated for the 2-year interval. The findings were not attributable to potential influences, such as hair treatment. The product-moment correlation showed nearly identical consistency with previous research regarding the 1-year test-retest interval. There was no significant product-moment correlation for the 2-year interval. Overall, these findings indicate that within a temporal framework of 1 year, HCCs may be stable predictors in correlational studies where the focus is on the rank orders of measured values.

BACKGROUND: Cortisol is a biological marker of stress, and its levels reflect the hypothalamic-pituitary-adrenal (HPA) axis response to stress over time. Saliva, blood, and urine cortisol reflect acute stress, whereas assessment of hair cortisol is a better reflection of chronic stress. There is limited information on hair cortisol concentration (HCC) in the perinatal period, particularly, in the preconception and postpartum periods. In addition to being a biomarker for stress, high levels of cortisol are typically associated with poor psychosocial outcomes, and adverse pregnancy outcomes. The objectives of this study were: (1) to measure HCC from six months preconception to six months postpartum; (2) to examine the relationship between HCC and demographic characteristics, depressive symptoms, and perceived stress in the first six months postpartum period; (3) and to assess the associations between HCC and systemic inflammatory markers in the first six months postpartum.
METHODS: The analysis included 96 women from a longitudinal study with up to 3 study visits in the first six months postpartum. Blood and hair samples were collected at 1-2 months (PP1), 3-4 months (PP2), and 5-6 months (PP3) postpartum. We obtained sociodemographic information, depressive symptoms, and perceived stress scores at PP1-PP3. To quantify cortisol levels over time, 8 segments were derived corresponding to 6 (PC1) and 3 (PC2) months preconception as well as for each trimester (T1-T3) and postpartum (PP1-PP3). Eight cytokines (Granulocyte-macrophage colony-stimulating factor (GM-CSF), Interferon- gamma [IFN- γ], Interleukin [IL]-10, IL-2, IL-4, IL-6, IL-8, and Tumor necrosis factor-alpha (TNF- α) were measured in plasma in the postpartum samples. Univariate, bivariate, correlations, and linear mixed modelling were performed using SAS 9.4. Multiple testing correction was conducted for correlations using false discovery rate and a Q value of <0.05 was deemed significant.
RESULTS: Median HCC varied over time peaking in the third trimester and declining in the postpartum. Significant differences were noted in median cortisol levels by race with Black/African American postpartum women experiencing higher levels at all timepoints. Significantly, higher median cortisol levels were also observed at PP1 and PP2 for mothers who reported their relationship status as single. Ethnicity, education, median age, depressive symptoms, and perceived stress were not associated with median cortisol levels. Pro-inflammatory cytokines IFN- γ (q= 0.01; r=-0.50) and IL-8 (q= 0.00; r=-0.55) showed correlations with HCC at PP1.
CONCLUSIONS: HCC increased during pregnancy, peaking at T3 and declining PP consistent with previous work. Black/African American women and single women have significantly higher median cortisol levels in the postpartum period. The marked increase of HCC in Black women may be an important factor in understanding maternal health racial inequities. Future studies should investigate how the relationships between HCC, sociodemographics, and systemic cytokines impact perinatal outcomes.

UNASSIGNED: Most studies assessing hair cortisol were conducted with adults. As specific guidelines for infant hair collection are lacking, we developed a hair collection protocol for 12-month-old infants and assessed its acceptability and feasibility.
UNASSIGNED: Out of the total (N = 45), 95.6 % (n = 43) of caregivers consented to the procedure, while one caregiver did not consent (2.2 %), and another requested the procedure to be halted before required amount of hair had been reached (2.2 %). Furthermore, two (4.4 %) infants did not have enough hair for collection. There was no attrition due to infant fussiness/crying.
UNASSIGNED: We learned five lessons which can help to enhance reproducibility, mother\'s consent, and mother-infant comfort and acceptance of the procedure. The first lesson is to have the infant sit on the caregiver\'s lap to ensure the infant feels safe and remains relatively still. The second is to reassure caregivers by showing hair samples representing the amount to be cut as well as by clarifying no unaesthetic gaps would be visible. The third is to caress the infant\'s head to habituate them to the hair manipulation and to make soap bubbles as distractors. The fourth is to take extra care when securing the lock of hair for cutting because the infant scalp is thin and malleable. The fifth is to place a precision scale in the collection room to ensure the necessary weight is reached.
UNASSIGNED: Our hair collection protocol developed for 12-month-old infants was deemed feasible and acceptable, filled an important literature gap concerning the absence of published protocols for infants, and will contribute to increase the replicability and collection efficiency for other research teams.

OBJECTIVE: Partners of breast cancer (BC) survivors report high rates of psychological distress including fear of cancer recurrence (FCR). Research suggests that partners may have poorer physical health outcomes than the general population, but little research has examined the physiological biomarkers by which distress may impact partner health outcomes. The current study examined the associations between FCR and changes in hair cortisol among BC partners.
METHODS: Male partners (N = 73) of early-stage BC survivors provided hair samples during two visits, one after completion of survivors\' adjuvant treatment (T1) and again 6 months later (T2). Two subscales from the Fear of Cancer Recurrence Inventory and one subscale from the Concerns about Recurrence Scale comprised a latent FCR factor at T1. A latent change score model was used to examine change in cortisol as a function of FCR.
RESULTS: Partners were on average 59.65 years of age (SD = 10.53) and non-Hispanic White (83%). Latent FCR at T1 was positively associated (b = 0.08, SE = 0.03, p = .004, standardized β = .45) with change in latent hair cortisol from T1 to T2.
CONCLUSIONS: Results indicated that greater FCR was associated with increases in hair cortisol in the months following adjuvant treatment. This is one of the first studies to examine the physiological correlates of FCR that may impact health outcomes in BC partners.
CONCLUSIONS: Findings highlight the need for further research into the relationship between FCR and its physiological consequences. Interventions to address partner FCR are needed and may aid in improving downstream physical health outcomes.

BACKGROUND: Substance use is highly prevalent among women experiencing intimate partner violence (IPV) and has been associated with dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis and resulting cortisol response. Posttraumatic stress disorder (PTSD) symptoms may play an important role in exacerbating the association between cortisol levels and substance use behaviors.
OBJECTIVE: This study examined the role of PTSD symptoms in the relation between cortisol and past month substance use behaviors. The current study used hair cortisol as an index of past 30-day HPA-axis functioning and ecological momentary assessment (EMA) to characterize substance use behaviors more accurately over a 30-day period.
METHODS: Participants were 90 community women who had experienced physical or sexual IPV in the past 30 days by their current male partner and used any amount of alcohol or drugs (M age = 40.71; 54.4 % white). Participants completed (a) a baseline interview, (b) EMA for 30-days, and (c) a follow up interview where they were asked to provide a hair sample for cortisol analyses. Data collection took place from 2018 to 2020.
RESULTS: PTSD severity moderated the relations between cortisol and days of drinking and binge drinking. In the context of high PTSD symptomology, women with high cortisol levels spent, on average, an additional 7.4 days drinking and 8.1 days binge drinking in the past 30 days compared to women with low cortisol levels, in a model adjusted for age.
CONCLUSIONS: Results highlight the prominent role of PTSD symptoms in the association between cortisol and alcohol use among women experiencing IPV.

Although neighborhood contexts serve as upstream determinants of health, it remains unclear how these contexts \"get under the skin\" of Mexican-origin youth, who are disproportionately concentrated in highly disadvantaged yet co-ethnic neighborhoods. The current study examines the associations between household and neighborhood socioeconomic status (SES), neighborhood racial-ethnic and immigrant composition, and hair cortisol concentration (HCC)-a physiological index of chronic stress response-among Mexican-origin adolescents from low-income immigrant families in the United States. A total of 297 (54.20% female; mage = 17.61, SD = 0.93) Mexican-origin adolescents had their hair cortisol collected, and their residential addresses were geocoded and merged with the American Community Survey. Neighborhoods with higher Hispanic-origin and foreign-born residents were associated with higher neighborhood disadvantage, whereas neighborhoods with higher non-Hispanic White and domestic-born residents were associated with higher neighborhood affluence. Mexican-origin adolescents living in neighborhoods with a higher proportion of Hispanic-origin residents showed lower levels of HCC, consistent with the role of the ethnic enclave. In contrast, adolescents living in more affluent neighborhoods showed higher levels of HCC, possibly reflecting a physiological toll. No association was found between household SES and HCC. Our findings underscore the importance of taking sociocultural contexts and person-environment fit into consideration when understanding how neighborhoods influence adolescents\' stress physiology.

The study objective was to investigate the effect of repeated hypothalamic-pituitary-adrenal (HPA) axis stimulation using synthetic adrenocorticotropic hormone (ACTH) intramuscular injections on hair cortisol concentration, growth, and behavior in preweaned dairy calves. Twenty-seven Holstein calves were assigned to nine triads (based on sex and birth order) and randomly assigned to 1 of 3 treatments: 1) control (CON; 2 mL saline weekly); 2) moderate (MOD; alternating Cosyntropin [2 mcg/kg body weight (BW)] and saline weekly); or 3) frequent (FREQ; Cosyntropin [2 mcg/kg BW] weekly). Calves received their first injection on study day 0 (7 ± 1 d of age). Hair was collected from the tail switch between days -5 and -3 (baseline), 21, and 49 and analyzed for cortisol concentration. To verify the endogenous cortisol release by Cosyntropin during the treatment period, saliva was collected on days 0, 14, 28, and 42 before injection and every 15 min for 2 h after injection for analysis of salivary cortisol concentration. Calves were fitted with accelerometers to continuously monitor lying time, number of lying bouts, and lying bout duration throughout the study. Growth measures (BW, hip height, hip width) were recorded weekly. Data were analyzed using repeated measures ANOVA (SAS, Version 9.4), and models included the fixed effects of treatment, time (min or study day), and interaction between treatment and time. Temperature humidity index was included as a continuous covariate in all models. We observed a treatment × min interaction (P < 0.0001), whereby salivary cortisol concentration was lower in CON calves compared to MOD and FREQ calves 15 to 120 min postinjection. While hair cortisol concentration was not influenced by treatment, concentration decreased from day 21 (1.28 ± 0.03 ng/mL) to 49 (0.93 ± 0.03 ng/mL). Average BW was similar across treatments (CON [59.4 ± 1.09 kg], MOD [58.6 ± 0.98 kg], and FREQ [57.6 ± 0.96 kg]; P = 0.50). There was no evidence to suggest a difference in average daily lying time (CON [18.5 ± 0.23 h/d], MOD [18.6 ± 0.23 h/d], and FREQ [18.5 ± 0.23 h/d]; P = 0.99). These results suggest that repeated HPA axis stimulation through Cosyntropin administration increased salivary cortisol concentration, but did not influence hair cortisol concentration, growth, or behavior in preweaned dairy calves.
Measures to quantify long-term or chronic stress in livestock are limited. The amount of cortisol (a stress hormone) deposited in the hair has been used as a noninvasive measure of long-term stress in some livestock species; however, few studies have investigated its use in young dairy calves. The objective of this study was to determine the efficacy of hair cortisol as a less invasive measure of stress in calves. Calves were either injected with saline (control) or Cosyntropin, a hormone that activates the stress response system, at different frequencies during the first two months of life. Cosyntropin injection increased salivary cortisol concentration (an indicator of acute stress) but did not increase hair cortisol concentration. There was no evidence to suggest a significant effect of treatment on calf growth. Calf behavior was similar between treatment groups. These results suggest that the method used to activate the stress response system in this study was sufficient to induce an acute stress response in calves (as indicated by increased salivary cortisol concentration), and more research is needed to investigate measures of chronic stress in young dairy calves.

Multiple sclerosis (MS) is a chronic neurological disease frequently associated with significant fatigue, anxiety, depression, and stress. These symptoms are difficult to treat, and prominently contribute to the decreases in quality of life observed with MS. The underlying mechanisms of these \"silent\" symptoms are not well understood and include not just the psychological responses to a chronic disease, but also biological contributions from bidirectional psycho-neuro-immune (dys)regulation of systemic inflammatory biology. To address these issues, we conducted a prospective, observational pilot study to investigate the psychological, biological, and neuroarchitecture changes associated with a mindfulness-based stress reduction (MBSR) program in MS. The overarching hypothesis was that MBSR modulates systemic and central nervous system inflammation via top-down neurocognitive control over forebrain limbic areas responsible for the neurobiological stress response. 23 patients were enrolled in MBSR and assessed pre/post-program with structural 3 T MRI, behavioral measures, hair cortisol, and blood measures of peripheral inflammation, as indexed by the Conserved Transcriptional Response to Adversity (CTRA) profile. MBSR was associated with improvements across a variety of behavioral outcomes, as well as on-study enlargement of the head of the right hippocampus. The CTRA analyses revealed that greater inflammatory gene expression was related to worse patient-reported anxiety, depression, stress, and loneliness, in addition to lower eudaimonic well-being. Hair cortisol did not significantly change from pre- to post-MBSR. These results support the use of MBSR in MS and elucidate inflammatory mechanisms related to key patient-reported outcomes in this population.

BACKGROUND: Children\'s exposure to chronic stress is associated with several health problems. Measuring hair cortisol concentration is particularly useful for studying chronic stress but much is unknown about hair cortisol determinants in children and adolescents, and previous research has often not considered the simultaneous exposure of multiple variables. This research is focused on investigating the relationship between environmental, social and individual factors with hair cortisol concentration in children.
METHODS: The data used in this study are from the INMA prospective epidemiological cohort study. The assessment of chronic stress was made on the basis of hair samples taken at the age of 11 years in the INMA-Gipuzkoa cohort (n = 346). A metamodel summarizing the hypothesized relationships among environmental, social and individual factors and hair cortisol concentration was constructed based on previous literature. Structural Equation Modelling was performed to examine the relationships among the variables.
RESULTS: In the general model higher behavioural problems were associated with higher cortisol levels and an inverse relationship between environmental noise and cortisol levels was observed, explaining 5 % of the variance in HCC. Once stratified by sex these associations were only hold in boys, while no significant effect of any of the study variables was related with cortisol levels in girls. Importantly, maternal stress was positively related to behavioural difficulties in children. Finally, higher traffic-related air pollution and lower exposure to neighborhood greenness were related to higher environmental noise.
CONCLUSIONS: This study highlights that simultaneous exposure to different environmental, social and individual characteristics may determine the concentration of hair cortisol. More research is needed and future studies should include this complex view to better understanding of hair cortisol determinants in children.

BACKGROUND: Autistic children are prone to experience heightened levels of distress and physiological reactivity to a range of sensory, social, and emotional stimuli. In line with this, multiple studies have demonstrated that autistic children have higher acute cortisol stress responses to adverse or threatening stimuli and altered cortisol awakening responses. However, few studies have examined whether this sensitivity may relate to heightened levels of chronic stress and persistently elevated hypothalamic-pituitary-adrenal (HPA) axis activity. The measurement of cortisol accumulation in hair is considered a non-invasive biomarker of chronic stress and has been associated with several childhood diseases. Here, we investigated whether hair cortisol concentration in a large sample of autistic children differed from non-autistic children, and after accounting for a range of child, parental and family-level characteristics.
METHODS: Hair cortisol concentration was measured in 307 autistic children and 282 non-autistic controls aged between 2 and 17 years recruited from four Australian states who participated in providing hair samples and demographic data to the Australian Autism Biobank. Independent samples t-test or one-way analysis of variance (ANOVA) were conducted to determine significant differences in the mean hair cortisol concentration (pg/mg) between potential covariates. Primary analysis included multivariable regression modelling of the collapsed sample to identify variables that were significantly associated with hair cortisol concentration after controlling for covariates. We also accounted for the potential interaction of multiple biological (e.g., age, sex, BMI) and psychosocial characteristics at the level of the child, the mother and the father, and the family unit.
RESULTS: Our findings suggest that the diagnosis of autism was not a significant predictor of chronic stress, as measured by hair cortisol concentration. However, findings of the multivariable regression analysis showed that key factors such as area of residence (Queensland vs Victorian state of residence) and decrease in child\'s age were significantly associated with higher hair cortisol concentration whereas lower family income was significantly associated with higher hair cortisol concentration.
CONCLUSIONS: To our knowledge, this is the first study to show that socioeconomic factors such as family annual income affect hair cortisol status in autistic children, indicating that the psychosocial environment may be a potential mediator for chronic stress in autistic children just as it has been demonstrated in non-autistic children.