Minireview: Hair cortisol: a novel biomarker of hypothalamic-pituitary-adrenocortical activity

Childhood trauma and hair cortisol response over the year following onset of a chronic life event stressor

OBJECTIVE

Childhood trauma may contribute to poor lifelong health in part through programming of the HPA-axis response to future life stressors. To date, empirical evidence shows an association of childhood trauma with dysregulation of the HPA-axis and blunted cortisol reactivity to acute stressors. Here, we conduct an initial examination of childhood trauma as a moderator of changes over time in perceived stress levels and HPA-axis response to a major chronic stressor in adulthood.

METHODS

Participants were 83 maternal caregivers of children newly diagnosed with cancer who completed the Childhood Trauma Questionnaire (CTQ), and who, over the year following their child's cancer diagnosis, had hair samples collected up to 7 times for the assessment of cortisol and completed monthly measures of perceived stress.

RESULTS

CTQ scores were in the expected range for a community sample and associated with changes in perceived stress and cortisol concentration over time (γ =.003, p =.002; γ = -.0004, p =.008, respectively) independently of age, education, treatment intensity and randomization to stress management intervention. Maternal caregivers who endorsed lower childhood trauma showed a steeper decline in perceived stress and a larger increase in cortisol levels across the year than caregivers who recalled more childhood trauma.

CONCLUSIONS

Findings extend animal models and studies that examine cortisol reactivity to acute stressors and suggest that childhood trauma may program a phenotype that is more psychologically reactive but shows a blunted HPA-axis response to chronic stress. While adaptive in the short-term, this early life programming may incur long-term costs for health. Further work is warranted to examine this possibility.

Hair Cortisol Concentrations in Opioid-Exposed versus Nonexposed Mother-Infant Dyads

OBJECTIVE

 To pilot measurement of hair cortisol concentration (HCC) in pregnant women with opioid use disorder and their infants over time and study the potential utility of hair cortisol as a biomarker of chronic stress in this population.

STUDY DESIGN

 In this pilot prospective cohort study of mother-infant dyads with and without prenatal opioid exposure, we obtained mother-infant HCCs at delivery and again within 1 to 3 months' postpartum. HCCs were compared between the opioid and control groups and between the two time points.

RESULTS

 There were no significant differences between opioid and control group maternal or infant HCCs at either time point. However, within the opioid-exposed group, there was a significant increase in infant HCCs across the two time points.

CONCLUSION

 This pilot study describes our experience with the measurement of HCCs in opioid-exposed mother-infant dyads.

KEY POINTS

· Maternal stress impacts fetal and child health.. · Many stressors in pregnant women with opioid use disorder.. · Hair cortisol may be a useful stress biomarker..

Do cows with stereotypic tongue-rolling behaviour cope better with their environment?

Introduction

Stereotypic behaviours, especially oral stereotypic behaviours, are frequently expressed in farm animals. Tongue-rolling is the most common oral stereotypic behaviour in dairy cows (Bos taurus). If animals frequently display stereotypic behaviours, this is an indication of poor welfare. It has been suggested that animals express stereotypic behaviours as a way of coping with stress. As a result, animals with stereotypic behaviours may have lower levels of stress hormones than animals without stereotypic behaviours.

Methods

In this study, 916 Holstein cows in the first lactation were subjected to scan sampling behavioural observations 200 times for 10 days. All cows were assigned to either a stereotypic behaviours group (SB) or a control group (CON). The SB group was further subdivided into a tongue-rolling group (TR) and an other-stereotypic behaviours group (OS). The TR group was also split into an only tongue-rolling group (OTR) and a mixed tongue-rolling and other stereotypic behaviours group (TROS). Some cows in the TR group belonged to an extreme tongue-rolling group (ETR). Hair and saliva samples were collected from 601 cows to test cortisol concentrations and dairy herd improvement (DHI) data were collected from a total of 762 cows.

Results

There were no differences in hair or saliva cortisol concentrations between the groups (p>0.05), and the frequencies of tongue-rolling were not associated with cortisol concentrations (p>0.05). For DHI in cows, the milk protein percentage (p = 0.028), milk true protein percentage (p = 0.021) and milk crude protein percentage (p = 0.023) of cows in the ETR group were significantly lower than those in the CON group. For cows in ETR group, as the frequencies of tongue-rolling increased, the milk protein percentage (p = 0.034, r = 0.365), milk true protein percentage (p = 0.022, r = 0.393) and milk crude protein percentage (p = 0.035, r = 0.363) increased.

Discussion

We investigated the relationship between stereotypic behaviours and stress by using a non-invasive sampling method to minimise harm to the cows. We suggest that tongue-rolling may not be a way for cows to cope with stress, at least in terms of cortisol concentrations.

The Impact of Environmental Enrichment on the Cortisol Level of Shelter Cats

Enriching cats' living environment in shelters is crucial in reducing their stress. Easier access to resources allows cats to display natural behavior. This study aimed to assess whether cats staying in an enriched environment would be less stressed than cats staying in a standard environment. The first group consisted of cats living in an environment with fewer resources (standard environment)-103 cats. The second group consisted of cats living in an enriched environment-76 cats. The research material consisted of hair collected to determine the cortisol level. The results indicate that cats from a more enriched environment have almost half the level of cortisol in hair than cats from an environment with fewer resources (0.059 ng/mg vs. 0.101 ng/mg; p = 0.000001).

Non-invasive methods for analysing pig welfare biomarkers

At present, the assessment of pig welfare quality has gained significant importance, prompting the exploration of novel biomarkers for this purpose. Traditionally, these biomarkers have been monitored in the blood; however, blood sampling is considered an invasive procedure. Currently, non-invasive methods for collecting samples are emerging as viable alternatives for assessing these biomarkers. This article aims to present the current knowledge regarding the use of non-invasive methods for analysing pig welfare biomarkers, specifically focusing on the saliva, hair, faeces, and urine as matrices to determine these biomarkers. The saliva analysis encompasses various biomarkers, such as cortisol, alpha-amylase, chromogranin A, the total esterase, oxytocin, acute phase proteins, adenosine deaminase, immunoglobulins and parameters of redox homeostasis. Cortisol, a specific biomarker, can be determined in the hair, urine and faeces, while urine samples allow for the analysis of catecholamines as non-invasive markers of pig welfare.

Intersectional stigma and the non-communicable disease syndemic in the context of HIV: protocol for a multisite, observational study in the USA

INTRODUCTION

The increasing burden of non-communicable diseases, such as hypertension, diabetes and dyslipidaemia, presents key challenges to achieving optimal HIV care outcomes among ageing people living with HIV. These diseases are often comorbid and are exacerbated by psychosocial and structural inequities. This interaction among multiple health conditions and social factors is referred to as a syndemic. In the USA, there are substantial disparities by social position (ie, racial, ethnic and socioeconomic status) in the prevalence and/or control of non-communicable diseases and HIV. Intersecting stigmas, such as racism, classism and homophobia, may drive these health disparities by contributing to healthcare avoidance and by contributing to a psychosocial syndemic (stress, depression, violence victimisation and substance use), reducing success along the HIV and non-communicable disease continua of care. Our hypothesis is that marginalised populations experience disparities in non-communicable disease incidence, prevalence and control, mediated by intersectional stigma and the psychosocial syndemic.

METHODS AND ANALYSIS

Collecting data over a 4 year period, we will recruit sexual minority men (planned n=1800) enrolled in the MACS/WIHS Combined Cohort Study, a long-standing mixed-serostatus observational cohort in the USA, to investigate the following specific aims: (1) assess relationships between social position, intersectional stigma and the psychosocial syndemic among middle-aged and ageing sexual minority men, (2) assess relationships between social position and non-communicable disease incidence and prevalence and (3) assess relationships between social position and HIV and non-communicable disease continua of care outcomes, mediated by intersectional stigma and the psychosocial syndemic. Analyses will be conducted using generalised structural equation models using a cross-lagged panel model design.

ETHICS AND DISSEMINATION

This protocol is approved as a single-IRB study (Advarra Institutional Review Board: Protocol 00068335). We will disseminate results via peer-reviewed academic journals, scientific conferences, a dedicated website, site community advisory boards and forums hosted at participating sites.

The Levels of Cortisol and Selected Biochemical Parameters in Red Deer Harvested during Stalking Hunts

As a reactive species, the red deer is sensitive to both negative exogenous and endogenous stimuli. An intensive hunting period may have a particularly negative impact on game animals. The aim of this study was to determine the plasma cortisol level and biochemical parameters in 25 wild red deer (Cervus elaphus) harvested during stalking hunts in correlation with the sex and age of the animals. The mean cortisol concentrations in the stags and hinds analyzed in this study were similar (20.2 and 21.5 ng/mL, respectively). Higher HDL cholesterol values were found in the blood of the hinds than in stags (p < 0.05). Similarly, the mean levels of LDL cholesterol, lactate dehydrogenase, and alanine aminotransferase were higher by 21%, 16%, and 42%, respectively, in the blood of the hinds. In contrast, the levels of alkaline phosphatase, bilirubin, and aspartate aminotransferase were higher in the stags (by 30%, 49%, and 36%, respectively). There was a negative correlation of the cortisol concentration with urea and bilirubin and a positive correlation between cortisol and aspartate aminotransferase in the stags (p < 0.05). In turn, a negative correlation was found between the cortisol and urea levels in the hinds (p < 0.05). In summary, the stress caused by stalking hunts and the characteristic behavior of red deer during the mating season had an impact on chosen biochemical parameters. The increased concentration of cortisol resulted in a decrease in the carcass mass, which may lead to the deterioration of the physical condition of animals on hunting grounds.

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

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

Design of a Remote Time-Restricted Eating and Mindfulness Intervention to Reduce Risk Factors Associated with Early-Onset Colorectal Cancer Development among Young Adults

Early-onset colorectal cancer (EOCRC) is defined as a diagnosis of colorectal cancer (CRC) in individuals younger than 50 years of age. While overall CRC rates in the United States (US) decreased between 2001 and 2018, EOCRC rates have increased. This research project aims to evaluate the feasibility and acceptability of Time-Restricted Eating (TRE), Mindfulness, or TRE combined with Mindfulness among young to middle-aged adults at risk of EOCRC. Forty-eight participants will be randomly assigned to one of four groups: TRE, Mindfulness, TRE and Mindfulness, or Control. Data on feasibility, adherence, and acceptability will be collected. Measures assessed at baseline and post-intervention will include body weight, body composition, dietary intake, physical activity, sleep behavior, circulating biomarkers, hair cortisol, and the gut microbiome. The effects of the intervention on the following will be examined: (1) acceptability and feasibility; (2) body weight, body composition, and adherence to TRE; (3) circulating metabolic, inflammation, and oxidative stress biomarkers; (4) intestinal inflammation; and (5) the gut microbiome. TRE, combined with Mindfulness, holds promise for stress reduction and weight management among individuals at risk of EOCRC. The results of this pilot study will inform the design and development of larger trials aimed at preventing risk factors associated with EOCRC.

Evaluating Mixtures of Urinary Phthalate Metabolites and Serum Per-/Polyfluoroalkyl Substances in Relation to Adolescent Hair Cortisol: The HOME Study

Results of toxicological studies indicate that phthalates and per-/polyfluoroalkyl substances (PFAS), 2 classes of endocrine-disrupting chemicals, may alter the functioning of the hypothalamic-pituitary-adrenocortical (HPA) axis. We evaluated the associations of urinary phthalate metabolites and serum PFAS during gestation and childhood with adolescent hair cortisol concentrations (pg/mg hair) at age 12 years, an integrative marker of HPA axis activity (n = 205 mother-child pairs; Cincinnati, Ohio; enrolled 2003-2006). We used quantile-based g-computation to estimate associations between mixtures of urinary phthalate metabolites or serum PFAS and hair cortisol. We also examined whether associations of individual phthalate metabolites or PFAS with cortisol varied by the timing of exposure. We found that a 1-quartile increase in all childhood phthalate metabolites was associated with 35% higher adolescent hair cortisol (phthalate mixture ψ = 0.13; 95% confidence interval: 0.03, 0.22); these associations were driven by monoethyl phthalate, monoisobutyl phthalate, and monobenzyl phthalate. We did not find evidence that phthalate metabolites during gestation or serum PFAS mixtures were related to adolescent hair cortisol concentrations. We found suggestive evidence that higher childhood concentrations of individual PFAS were related to higher and lower adolescent hair cortisol concentrations. Our results suggest that phthalate exposure during childhood may contribute to higher levels of chronic HPA axis activity.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Hair cortisol concentration in finishing pigs on commercial farms: variability between pigs, batches, and farms

Hair cortisol is a stress indicator and could be used to assess the pigs' exposure to stressors in the weeks/months prior to non-invasive hair sampling. The main aim of this study was to describe the hair cortisol concentration (HCC) variability between individuals within a batch, between farms and between batches within a farm. The secondary aim was to determine how the number of sampled pigs influences the characterization of HCC within a batch. Twenty farrow-to-finish pig farms were recruited considering the diversity of their management practices and health status (data collected). Hair was sampled in two separate batches, 8 months apart. The necks of 24 finishing pigs were clipped per batch the week prior to slaughter. To describe the variability in HCC, an analysis of the variance model was run with three explanatory variables (batch, farm and their interaction). To identify farm clusters, a principal component analysis followed by a hierarchical clustering was carried out with four active variables (means and standard deviations of the two batches per farm) and 17 supplementary variables (management practices, herd health data). We determined how the number of sampled pigs influenced the characterization of HCC within a batch by selecting subsamples of the results. HCC ranged from 0.4 to 121.6 pg/mg, with a mean of 25.9 ± 16.2 pg/mg. The variability in HCC was mainly explained by differences between pigs (57%), then between farms (24%), between batches within the same farm (16%) and between batches (3%). Three clusters of farms were identified: low homogeneous concentrations (n = 3 farms), heterogeneous concentrations with either higher (n = 7) or lower (n = 10) HCC in batch 2 than in batch 1. The diversity of management practices and health statuses allowed to discuss hypotheses explaining the HCC variations observed. We highlighted the need to sample more than 24 pigs to characterize HCC in a pig batch. HCC differences between batches on six farms suggest sampling pigs in more than one batch to describe the HCC at the farm level. HCC variations described here confirm the need to study its links with exposure of pigs to stressors.

Quality of hematology and clinical chemistry results in laboratory and zoo nonhuman primates: Effects of the preanalytical phase. A review

Most errors in clinical pathology originate in the preanalytical phase, which includes all steps from the preparation of animals and equipment to the collection of the specimen and its management until analyzed. Blood is the most common specimen collected in nonhuman primates. Other specimens collected include urine, saliva, feces, and hair. The primary concern is the variability of blood hematology and biochemistry results due to sampling conditions with the effects of capture, restraint, and/or anesthesia. Housing and diet have fewer effects, with the exception of food restriction to reduce obesity. There has been less investigation regarding the impact of sampling conditions of nonblood specimens.

Technical validation and a comparison of two methods to quantify individual levels of glucocorticoids in Alpine marmot hair

Quantification of cortisol concentration in hair has become a promising conservation tool for non-invasive monitoring of "stress" in wild populations, yet this method needs to be carefully validated for each species. The goals of the study were:•Immunologically validate two methods (study 1 and 2 respectively) to extract and quantify cortisol in the hair of wild Alpine marmots.•Compare the amount of cortisol extracted from hair samples using two methods i.e. cut into fine pieces (study 1) and hair samples pulverized using a ball mill (study 2).•Determine the extent to which methods in study 2 could provide individual specific hair cortisol (HC) measures when samples were taken from the same body location. Within and between individual variations in HC levels were examined from multiple hair samples from 14 subjects in study 2. We evaluated if inter-individual variations in HC levels could be explained by sex and age.At least twice the amount of cortisol was obtained per g/hair when samples were pulverized in a ball mill prior to extraction compared to when cut into pieces. Our methods demonstrated intra-individual consistency in HC at a given time point: inter-individual variation in HC was three times larger than within individual variance. Sex and age did not impact HC levels.

Adolescents' hair cortisol concentrations during COVID-19: Evidence from two longitudinal studies in the Netherlands and the United States

BACKGROUND

Prolonged stress exposure is associated with alterations in cortisol output. The COVID-19 pandemic represented a stressor for many, including children. However, a high-quality caregiving environment may protect against psychological problems and possibly against elevations in cortisol. We examined adolescents' physiological stress responses to the pandemic and the role of attachment in two longitudinal samples from the Netherlands and the United States (https://aspredicted.org/HHY_8MK).

METHODS

Cortisol was assessed from hair samples before and during the pandemic, while attachment was self-reported prepandemic. Study 1 included a Dutch sample (N = 158; examined at ages 10 and later at 14 years old), whereas Study 2 included a US sample (N = 153; examined at ages 9-11 and again 2 years later) and an age-matched prepandemic sample (N = 29, 10-13 years old). Repeated-measures analyses of variance examined changes in cortisol from prepandemic to during the pandemic and the effect of attachment in each sample separately.

RESULTS

After accounting for age, both studies revealed nonsignificant changes in hair cortisol and a nonsignificant effect of attachment. A significant effect of sex emerged in Study 1, with Dutch girls showing a significant cortisol increase during the pandemic, which was not explained by puberty.

CONCLUSION

These findings suggest differential associations of the pandemic with hair cortisol increases by sex and country.

The Role of Cortisol in Chronic Stress, Neurodegenerative Diseases, and Psychological Disorders

Cortisol, a critical glucocorticoid hormone produced by the adrenal glands, plays a pivotal role in various physiological processes. Its release is finely orchestrated by the suprachiasmatic nucleus, governing the circadian rhythm and activating the intricate hypothalamic-pituitary-adrenal (HPA) axis, a vital neuroendocrine system responsible for stress response and maintaining homeostasis. Disruptions in cortisol regulation due to chronic stress, disease, and aging have profound implications for multiple bodily systems. Animal models have been instrumental in elucidating these complex cortisol dynamics during stress, shedding light on the interplay between physiological, neuroendocrine, and immune factors in the stress response. These models have also revealed the impact of various stressors, including social hierarchies, highlighting the role of social factors in cortisol regulation. Moreover, chronic stress is closely linked to the progression of neurodegenerative diseases, like Alzheimer's and Parkinson's, driven by excessive cortisol production and HPA axis dysregulation, along with neuroinflammation in the central nervous system. The relationship between cortisol dysregulation and major depressive disorder is complex, characterized by HPA axis hyperactivity and chronic inflammation. Lastly, chronic pain is associated with abnormal cortisol patterns that heighten pain sensitivity and susceptibility. Understanding these multifaceted mechanisms and their effects is essential, as they offer insights into potential interventions to mitigate the detrimental consequences of chronic stress and cortisol dysregulation in these conditions.

Amniotic fluid cortisol predicts neonatal and infant development in non-stressed rhesus monkeys: Implications for prenatal stress

Prenatal stress adversely affects offspring development, with fetal cortisol (CORT) exposure being a primary hypothesized mechanism for stress-induced developmental deficits. Fetal CORT exposure can be assessed via measurements in amniotic fluid. However, in humans, amniocentesis is typically only performed for clinical reasons such as karyotyping; thus, amniotic fluid CORT cannot be obtained from a random sample. To test the hypothesis that fetal CORT exposure predicts neonatal and infant development in healthy primates, we measured amniotic fluid CORT in N = 18 healthy rhesus macaque (Macaca mulatta) dams (50:50 female:male infants) between 80 and 124 days gestation (mean ± SEM = 98.3 ± 2.9 days out of 165 days gestational length; i.e., second trimester). Maternal hair cortisol concentrations (HCCs) were assessed throughout pregnancy and lactation. Offspring were assessed for physical growth, neurological development, cognitive development, and HCCs across postnatal days 30-180. Controlling for gestational age at amniocentesis, higher amniotic fluid CORT significantly predicted slower infant growth rate (g/day) in the first 30 days (β = -0.19; R2 = 0.71, p = .008), poorer sensorimotor scores on the day 30 neonatal assessment (β = -0.28; R2 = 0.76, p = .015), and longer time to complete training (β = 0.48; R2 = 0.54, p = .026), but better performance (β = 0.91; R2 = 0.60, p = .011) on a discrimination cognitive task at 120-180 days. Amniotic fluid CORT was not associated with maternal or infant HCCs. Although these results are correlative, they raise the intriguing possibility that fetal CORT exposure in non-stress-exposed primates, as measured by amniotic fluid CORT, programs multiple aspects of neonatal and infant development. On the other hand, amniotic fluid CORT may not relate to chronic CORT levels in either mothers or infants when assessed by hair sampling.

Mindfulness Practice Reduces Hair Cortisol, Anxiety and Perceived Stress in University Workers: Randomized Clinical Trial

BACKGROUND

Anxiety and stress are common mental health conditions reported by university workers. Practices of mindfulness represent one promising approach as an effective and feasible means to reduce stress, improve mental health and promote well-being; however, there are no clinical trials that have combined long-term stress biomarkers (hair cortisol) and psychometric assessments in a sample of university workers.

OBJECTIVE

This study investigated the effectiveness of a mindfulness-based program on long-term stress, by measuring hair cortisol concentration and perceived stress and anxiety among workers who were undergoing high levels of stress.

METHOD

We conducted a randomized clinical trial at work among the employees of a public university. We compared a group that received the eight-week mindfulness intervention with the wait list group who received no intervention.

RESULTS

A total of 30 participants were included in the study, with n = 15 subjects in the intervention group and n = 15 in the control group. Hair cortisol, perceived stress and anxiety significantly reduced after the intervention compared to the control group, which had no appreciable decline in the measured variables.

CONCLUSION

This clinical trial showed the effectiveness of a mindfulness program on mental health psychometric measures (perceived stress and anxiety) and on a long-term stress biomarker (hair cortisol). It can be concluded that an eight-week mindfulness program could be implemented as an effective strategy to reduce stress biomarkers (hair cortisol) as well as perceived stress and anxiety, improving the mental health of university workers.

Hair Cortisol in Service Dogs for Veterans with Post-traumatic Stress Disorder Compared to Companion Dogs (Canis Familiaris)

Service dogs are trained to assist humans. This assistance potentially exposes them to stressors To investigate if service dogs are exposed to more stressors than companion dogs we questioned whether hair cortisol levels differed between both groups. We studied this by cutting a tuft of hair from the neck of 19 companion and 11 service dogs. Cortisol levels were subsequently analyzed via immunoassay and compared via a simple linear regression model. The influence of coat color, season, sex, other dogs, pets, or mental health diagnoses in the household was also checked . Results showed that cortisol values did not differ between service and companion dogs. Furthermore, none of the additional variables had an influence on cortisol levels. This lead to the conclusion that the service dogs in this study did not have higher hair cortisol levels than companion dogs Further study should be conducted as to why no difference did occur between groups and if this difference is persistent over time given that we only studied a period of up to two months' worth of hair cortisol.

Hair glucocorticoids are not a historical marker of stress - Exploring the time-scale of corticosterone incorporation into hairs in a rat model

Hair glucocorticoids are increasingly popular biomarkers, used across numerous research fields, and studied species, as a measure of stress. Although they are suggested to be a proxy of the average HPA axis activity spanning a period of weeks or months into the past, this theory has never been tested. In the present study, adrenalectomized rats with no endogenous (adrenal) glucocorticoid production were used to study how circulating glucocorticoid levels would be reflected in the glucocorticoid levels found in hair samples. By dosing the animals daily with high levels of corticosterone for seven days, while sampling hairs before, during, and after treatments, a timeline for glucocorticoid uptake into hairs was constructed. This kinetic profile was compared to two hypothetical models, and the theory that hair glucocorticoids are a record of historical stress had to be rejected. Corticosterone concentrations in hairs were found to increase within three hours of the first injection, the highest concentrations were found on the seventh day of treatments, and the decrease in concentrations post-treatment suggests rapid elimination. We speculate that hair glucocorticoid levels can only be used to characterize a stress-response for a few days following a postulated stressor. An updated model, where glucocorticoids diffuse into, along, and out of hairs needs to be adopted to reconcile the experimentally obtained data. The inescapable consequence of this updated model is that hair glucocorticoids become a marker of - and can only be used to study - recent, or ongoing, stress, as opposed to historical events, weeks or months in the past.

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

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

Indicators of improved gestation housing of sows. Part II: Effects on physiological measures, reproductive performance and health of the offspring

Prenatal stress is the mechanism through which poor welfare of pregnant sows has detrimental effects on the health and resilience of their piglets. We compared two gestation housing systems (IMPROVED versus [conventional] CONTROL) in terms of sow stress and welfare indicators and sought to determine whether potential benefits to the sows would translate into improved offspring health. Sows were mixed into 12 stable groups (six groups per treatment, 20 sows per group) 29 days post-service in pens with free-access, full-length individual feeding/lying-stalls. CONTROL pens had fully slatted concrete floors, with two blocks of wood and two chains suspended in the group area. IMPROVED pens were the same but with rubber mats and manila rope in each stall, and straw provided in three racks in the group area. Saliva was collected from each sow on day 80 of pregnancy and analysed for haptoglobin. Hair cortisol was measured in late gestation. Sows' right and left eyes were scored for tear staining in mid lactation and at weaning. Numbers of piglets born alive, dead, mummified, and total born were recorded. Piglets were weighed and scored for vitality and intra-uterine growth restriction (IUGR) at birth. Presence of diarrhoea in farrowing pens was scored every second day throughout the suckling period. IMPROVED sows had lower haptoglobin levels and tear-stain scores during lactation. IMPROVED sows produced fewer mummified piglets, and these had significantly lower IUGR scores, and scored lower for diarrhoea than piglets of CONTROL sows. Hence, improving sow welfare during gestation improved the health and performance of their offspring.

The Effect of Noise, Vibration, and Light Disturbances from Daily Health Checks on Breeding Performance, Nest Building, and Corticosterone in Mice

At our institution, the techniques that technicians use for health checks vary for mice housed in cages on individually ventilated caging (IVC) racks. If the mice cannot be adequately visualized, some technicians partially undock the cage whereas others use an LED flashlight. These actions undoubtedly alter the cage microenvironment, particularly with regard to noise, vibration, and light, which are known to affect multiple welfare and research-related parameters in mice. The central aim of this study was to assess the effects of partial cage undocking and LED flashlight use during daily health checks on fecundity, nest building scores, and hair corticosterone concentrations in C57BL/6J mice to determine the least disturbing method of performing these health checks. In addition, we used an accelerometer, a microphone, and a light meter to measure intracage noise, vibration, and light under each condition. Breeding pairs (n = 100 pairs) were randomly assigned to one of 3 health check groups: partial undocking, LED flashlight, or control (in which mice were observed without any cage manipulation). We hypothesized that mice exposed to a flashlight or cage undocking during daily health checks would have fewer pups, poorer nest building scores, and higher hair corticosterone levels than did the control mice. We found no statistically significant difference in fecundity, nest building scores, or hair corticosterone levels between either experimental group as compared with the control group. However, hair corticosterone levels were significantly affected by the cage height on the rack and the amount of time on study. These results indicate that a short duration, once-daily exposure to partial cage undocking or to an LED flashlight during daily healthy checks does not affect breeding performance or wellbeing, as measured by nest scores and hair corticosterone levels, in C57BL/6J mice.

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

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

Depressive-Like Effects of Foreclosing: A Cross-Sectional Study of Hair Cortisol Concentration

INTRODUCTION

Foreclosing and home eviction have been associated with various negative health outcomes, probably due to exposure to such stressful circumstance, but there is no evidence about foreclosure and home eviction to elicit cortisol responses.

METHODS

Participants who recently had received a court eviction notice were compared to subjects suffering a depressive disorder and to healthy controls in terms of hair cortisol concentrations.

RESULTS

Subjects under the stressful circumstance of foreclosure and patients with depression showed comparable concentrations in most of the hair segments while healthy subjects displayed the lowest levels of cortisol.

CONCLUSION

The findings show that foreclosure and home eviction are associated with increased cumulative hair cortisol and with depressive-like symptoms. Foreclosing procedures yielded to maintain high levels of cortisol which may increase the risk to develop major depression.

Incorporation of Testicular Ultrasonography and Hair Steroid Concentrations in Bull Breeding Soundness Evaluation

Testicular ultrasonography and steroid concentrations (cortisol, dehydroepiandrosterone sulfate (DHEA-S), cortisol/DHEA-S ratio, testosterone) in hair were examined for their utility in the bull breeding soundness evaluation (BBSE). Beef and dairy bulls (n = 16; 2.7 ± 0.4 years old; body condition score 3.2 ± 0.1) of five breeds were maintained under the same conditions at an accredited semen collection center. Bulls underwent routine semen collection twice weekly for 12 weeks and semen was processed and cryopreserved. Ultrasonography and hair sampling were undertaken at the last semen collection. Bulls with homogeneous testicular parenchyma (n = 8) had a higher (p < 0.05) percentage of motile sperm post-thawing compared with bulls with heterogeneous parenchyma (n = 8). There were no differences (p > 0.05) in the hair concentrations of cortisol, DHEA-S, and testosterone between bulls with homogeneous and heterogeneous parenchyma. In bulls with homogeneous parenchyma, hair DHEA-S concentration was positively correlated with percentage motile sperm (R² = 0.76), progressively motile sperm (R² = 0.70), and motility yield (R² = 0.71). The findings indicate that the integration of testicular ultrasonography and hair DHEA-S status in the BBSE could provide a more comprehensive assessment of indicative fertility in bulls. Additionally, ultrasonography can be used in the BBSE when the evaluation of semen parameters is not available.

Preconception sleep quality moderates the association between preconception hair cortisol levels and mental health in pregnant women

BACKGROUND

Poor sleep quality may elevate cortisol levels and affect prenatal mental health through altered HPA axis functioning. This study aims to examine whether subjective sleep quality during preconception moderates the association between preconception hair cortisol levels and mental health from preconception to pregnancy trimesters.

METHODS

Women from a prospective cohort study completed the Pittsburgh Sleep Quality Index (PSQI), the Edinburgh Postnatal Depression Scale (EPDS), and the State-Trait Anxiety Inventory (STAI) questionnaires during preconception (T0) and at each pregnancy trimesters (T1, T2, and T3). We analyzed 266 of these women who conceived and had fully completed measures at preconception for hair cortisol, sleep quality and either EPDS or STAI-state. Changes in EPDS and STAI-state scores were derived (i.e., T1-T0, T2-T0, T3-T0). Johnson-Neyman technique identified PSQI scores with significant moderation of cortisol on mental health.

RESULTS

After adjusting for potential covariates, there was a significant positive correlation between preconception hair cortisol levels and depressive symptom at the second trimester (r_s (144) = 0.22, p = 0.008), but not the first and third trimesters (all p_s > 0.05). The positive association between preconception hair cortisol and change in depressive symptoms between third trimester and preconception was significant only among women with poor preconception sleep quality (PSQI ≥ 7).

LIMITATIONS

Sleep quality and prenatal mood were derived from self-reported questionnaires, which may be more susceptible to bias.

CONCLUSIONS

The positive association between preconception hair cortisol and change in prenatal depressive symptoms is significant among women who reported poor sleep quality during preconception. Improving preconception sleep quality can potentially mitigate the association between preconception hair cortisol and depressive symptoms during pregnancy.

Sudanese Toombak smokeless tobacco users harbour significantly altered long-term cortisol body production

The Sudanese, in particular its male population, are known to utilise a smokeless tobacco product (Toombak) which is placed in the oral cavity and can be replaced several times a day. Toombak has been shown to harm human health and is highly addictive. The effect on body cortisol response over a retrospective period in users of this product has not been previously explored. In addition, psycho-dependency scores of Toombak users have not been analysed. In this study, 37 male subjects, age 18-45 years were recruited, of which 18 were non-users of Toombak and 19 were Toombak users. One hair sample was collected from each user and non-user of Toombak. Each hair sample (n=37) was placed in a pre-prepared long piece of foil with two labels on either side marked: 'scalp-side' and 'distant-side'. Cortisol was extracted by mincing 10 mg of 'scalp-side' hair, not exceeding 3 cm, with methanol addition, incubation, and sonication. Cortisol was measured using the enzyme-linked immunosorbent assay kit (Enzo Life Sciences, UK). The amount of hair cortisol in the samples was determined using spectrophotometry at wavelength 405 nm measured in pg/ml and visualised with a four parametric logistic curve. Toombak users were further asked to complete the Fagerstrom Test for Nicotine Dependence-Smokeless Tobacco questionnaire (FTND-ST) comprising of six questions. Scores of > 5 indicated a significant dependence, while a score of < 4 marked low to moderate dependence. The mean concentration of hair cortisol in Toombak users (9.7 pg/ml) was significantly lower (p=0.023) compared to non-users (19.4 pg/ml), with total concentrations ranging from 2.1 to 55.6 pg/ml. FTND-ST scores ranged from 4 to 9, with high levels of psycho-dependency (score > 5) and nicotine tolerance found in 85 % of Toombak users. Cortisol body release in Sudanese smokeless tobacco users was found to be significantly altered. While low cortisol levels do lead to anxiolytic effects, in the long-term, this can allow for increased susceptibility to low cortisol-associated diseases.

Physical Injuries and Hair Corticosterone Concentration in Rabbit Kits from Single- and Group-Housed Does Kept on a Commercial Farm

In intense breeding programs, rabbits are exposed to numerous stress factors which could affect their welfare and health. It has been suggested that group housing is more comfortable for does and similar to the living conditions of European wild rabbits. In this study, we compared three different housing systems—single housing; housing in pairs; and housing in groups of three does—to test whether there is a measurable impact on skin lesions, health, and hair corticosterone concentration (HCC) of their kits. The number of kits with lesions increased with the number of does kept together. The probability of kits getting injured was higher in groups of three does than in pens of single-housed does (p = 0.041). When does were pair-housed, kits seemed to have fewer disease symptoms compared to the other treatments. Concerning HCC of kits, there was no significant difference between the housing systems (p > 0.05). The mean HCC of kits was 2.94 pg/mg, while pair housing had the lowest HCC (2.59 pg/mg). This study focused on the welfare of kits from group-housed does. From this perspective, pair housing of does may be appropriate to allow social interaction between does without unduly affecting the welfare of their kits.

Brief Report: Above and Beyond Safety: Psychosocial and Biobehavioral Impact of Autism-Assistance Dogs on Autistic Children and their Families

Autism-Assistance Dogs (AADs) are highly-skilled service animals trained primarily to ensure the safety of an autistic child by preventing elopement and mitigating 'meltdowns'. Although anecdotal accounts and case-studies have indicated that AADs confer benefits above and beyond safety, empirical support anchored in validated clinical, behavioral, and physiological measures is lacking. To address this gap, we studied children and their families before and after receiving a well-trained AAD using a within-subject, repeated-measures design. Notably, this study is the first to assess change in a biomarker for chronic stress in both autistic children and their parents. Final analyses included pre-/post-AAD data from 11 triads (parent/handler-dog-child) demonstrating significantly positive psychosocial and biobehavioral effects of AADs.

Hair cortisol reduction and social integration enhancement after a mindfulness-based intervention in children

BACKGROUND

Over recent decades, chronic stress at an early age has become a worrying health problem in children. We seek to evaluate an intervention involving mindfulness-based practices and prosocial activities in 7- to 8-year-old children.

METHODS

Stress levels were determined using hair cortisol concentration (HCC), and social integration was measured by means of a sociogram. The program had previously proven to be effective in decreasing salivary cortisol levels and in favouring social integration in children. A total of 35 children participated in the study: 18 constituted the intervention group and 17 the wait-list group. In both groups, HCC and social integration were evaluated before and after the intervention conducted throughout an entire school year.

RESULTS

The experimental group showed a significant reduction in HCC, as well as significant enhancement of social integration levels, whereas no changes were observed in the wait-list group.

CONCLUSIONS

This is the first research to show that HCC, a reliable neuroendocrine indicator, decreased as a result of a mindfulness-based program. This successful outcome adds new evidence to previous findings regarding the reduction of chronic stress in children following participation in this program.

Stress Concepts and Applications in Various Matrices with a Focus on Hair Cortisol and Analytical Methods

When studying stress in animals, it is important to understand the types of stress and their classification, and how to assess the stress levels in different animal species using different matrices accurately and precisely. The classification of stress types helps to distinguish between good stress (eustress) and bad stress (distress). Hence, first, it is crucial to assess the animal's level of stress in a non-intrusive manner and second to identify the type of stress that is best suited to its environment. Third, it is also important to analyze the obtained samples using a suitable method to increase the validity of stress hormone measurements. Therefore, in this review, we aim to: (1) explain the classification of stress, (2) discuss the wide range of body matrices (e.g., saliva, milk, hair, urine, feces, sweat, fins, etc.) that can be used as samples to evaluate stress levels, as well as their comparisons and limitations, and present the reliable matrices for measuring stress hormones with special emphasis on hair, (3) compare the analytical methods for measuring stress hormones after sample preparation. Despite some literature that does not include hair as a reliable matrix for evaluating stress levels, hair is one of the matrices for measuring long-term stress hormone accumulations. This review discusses some factors that influence the level of stress hormones in the hair. By understanding these issues, the scientific community will not only be able to improve the understanding of stress and biomarker evaluation but also suggest how to deal with the consequences of stress in future research.

Association of maternal and paternal psychosocial stress and infant hair cortisol among Arab American immigrants: A pilot study

Acculturative stress is unique among immigrants and refers to the stress associated with maintaining cultural values and traditions in the host country. Immigrant parents confront psychosocial variables such as acculturative stress, anxiety, and depression that might result in intergenerational negative consequences on their infants. Measurement of hair cortisol concentration (HCC), an outcome of neuroendocrine dysregulation, is one relatively noninvasive approach to gauge stress in infants. No published studies have evaluated associations among parents' psychosocial variables and infants' HCC among immigrant families. Therefore, the purpose of this study was to: (1) examine the relationship between maternal and paternal psychosocial stress variables; and (2) examine the association between psychosocial variables of both parents (acculturative stress, anxiety, and depression) and infants' HCC among immigrant Arab American families. A sample of 31 immigrant Arab American triads (mother-father-infant) was recruited. During one home visit, each parent completed the study questionnaires separately when the baby was 6-24 months old and a hair sample was collected from the infant for HCC. Parents reported significant symptoms of anxiety (33% mothers; 45% fathers) and depression (33% mothers; 35.5% fathers). Paternal acculturative stress, anxiety, and depressive symptoms were significantly correlated to infants' HCC. Acculturative stress, anxiety, and depressive symptoms were significantly correlated between mother-father dyads. Future research should continue to focus on immigrant families and include both parents to better understand and improve infant health.

Effect of Single Housing on Innate Immune Activation in Immunodeficiency Virus-Infected Pigtail Macaques ( Macaca nemestrina ) as a Model of Psychosocial Stress in Acute HIV Infection

OBJECTIVE

Simian immunodeficiency virus (SIV) infection of macaques recapitulates many aspects of HIV pathogenesis and is similarly affected by both genetic and environmental factors. Psychosocial stress is associated with immune system dysregulation and worse clinical outcomes in people with HIV. This study assessed the impact of single housing, as a model of psychosocial stress, on innate immune responses of pigtailed macaques ( Macaca nemestrina ) during acute SIV infection.

METHODS

A retrospective analysis of acute SIV infection of 2- to si6-year-old male pigtailed macaques was performed to compare the innate immune responses of socially ( n = 41) and singly ( n = 35) housed animals. Measures included absolute monocyte count and subsets, and in a subset ( n ≤ 18) platelet counts and activation data.

RESULTS

SIV infection resulted in the expected innate immune parameter changes with a modulating effect from housing condition. Monocyte number increased after infection for both groups, driven by classical monocytes (CD14 + CD16 - ), with a greater increase in socially housed animals (227%, p < .001, by day 14 compared with preinoculation time points). Platelet numbers recovered more quickly in the socially housed animals. Platelet activation (P-selectin) increased by 65% ( p = .004) and major histocompatibility complex class I surface expression by 40% ( p = .009) from preinoculation only in socially housed animals, whereas no change in these measures occurred in singly housed animals.

CONCLUSIONS

Chronic psychosocial stress produced by single housing may play an immunomodulatory role in the innate immune response to acute retroviral infection. Dysregulated innate immunity could be one of the pathways by which psychosocial stress contributes to immune suppression and increased disease severity in people with HIV.

Impact of hair type, hair sample weight, external hair exposures, and race on cumulative hair cortisol

The biomarker cortisol assesses the impact of biopsychosocial stressors that activate the stress response system. Hair has emerged as a valid and non-invasive means of gauging cumulative cortisol deposited over month-long periods of time. Established protocols for the extraction of hair cortisol are being validated and refined in humans, yet methodological information about hair characteristics on cortisol remains limited. In addition to external hair exposures (e.g. dye, time spent outside), we examined hair categorization or type (e.g. kinky, straight) by extending a hair typing methodology for scientific use that is currently popular among hair care professionals. We then examined the interaction between hair type and race on cortisol levels with a hair questionnaire. Three studies were pooled to investigate how sample weight, hair type, race, heat exposures, and hair treatments impacted cumulative hair cortisol concentrations. Study 1 consisted of Adult Kenyan Medical Workers (N = 44); Study 2 Mexican and Mexican Americans (N = 106); and Study 3 American Youth (N = 107). We found significantly higher cortisol in 5 mg of hair when compared to larger sample weights, and higher cortisol in those who spent more time outdoors. Cortisol concentrations differed between racial groups and varied by hair type; moreover, there were directional differences in cumulative cortisol from straighter to curlier hair types which depended on racial group. In addition to demonstrating the impact of relatively novel control factors like hair sample weight, outdoor exposure, and hair type, the present study illustrates the importance of disentangling hair type and race to understand variability in cumulative hair cortisol. These influences should be included in future studies that measure hair cortisol.

Association between hair cortisol concentration and behavioral difficulties in children and adolescents

This study aimed to assess associations between behavioral difficulties and an objectively measurable indicator for long-term stress (hair cortisol) in children and adolescents. We expected increased hair cortisol levels in participants with more externalizing (conduct problems, hyperactivity/inattention) or internalizing (peer relationship problems, emotional problems) behavioral difficulties. Behavioral difficulties were assessed using the parent version of the Strengths and Difficulties Questionnaire (SDQ). Hair cortisol concentration (HCC), measured via liquid chromatography mass spectrometry (LC-MS3), was used as stress marker. A 1 cm strand of hair was cut off from the occipital or parietal cranium closest to the scalp. The study sample comprised 1321 children and adolescents aged between 3 and 17 years participating in the LIFE Child cohort study (Leipzig, Germany). To assess associations, we applied multiple linear regression analyses. Only a few associations met expectations, others contradicted our hypotheses. No association reached statistical significance. The present findings may suggest that behavioral difficulties gathered by SDQ are not associated with stress measured through HCC.

Child maltreatment and hypothalamic-pituitary-adrenal axis functioning: A systematic review and meta-analysis

Alterations in hypothalamic-pituitary-adrenal (HPA) axis and its effector hormone cortisol have been proposed as one possible mechanism linking child maltreatment experiences to health disparities. In this series of meta-analyses, we aimed to quantify the existing evidence on the effect of child maltreatment on various measures of HPA axis activity. The systematic literature search yielded 1,858 records, of which 87 studies (k = 132) were included. Using random-effects models, we found evidence for blunted cortisol stress reactivity in individuals exposed to child maltreatment. In contrast, no overall differences were found in any of the other HPA axis activity measures (including measures of daily activity, cortisol assessed in the context of pharmacological challenges and cumulative measures of cortisol secretion). The impact of several moderators (e.g., sex, psychopathology, study quality), the role of methodological shortcomings of existing studies, as well as potential directions for future research are discussed.

Selection of appropriate biomatrices for studies of chronic stress in animals: a review

Cortisol and corticosterone, hormones traditionally considered biomarkers of stress, can be measured in fluid biomatrices (e.g., blood, saliva) from live animals to evaluate conditions at sampling time, or in solid biomatrices (e.g., hair, feather) from live or dead animals to obtain information regarding long-term changes. Using these biomarkers to evaluate physiological stress responses in domestic animals may be challenging due to the diverse characteristics of biomatrices for potential measurement. Ideally, a single measurement from the biomatrix should be sufficient for evaluating chronic stress. The availability of appropriate and cost-effective immunoassay methods for detecting the biomarkers should also be considered. This review discusses the strengths and limitations of different biomatrices with regard to ensuring the highest possible reliability for chronic stress evaluation. Overall, solid biomatrices require less frequent sampling than other biomatrices, resulting in greater time- and cost-effectiveness, greater ease of use, and fewer errors. The multiplex immunoassay can be used to analyze interactions and correlations between cortisol and other stress biomarkers in the same biomatrix. In light of the lack of information regarding appropriate biomatrices for measuring chronic stress, this review may help investigators set experimental conditions or design biological research.

Hair cortisol concentration as a marker of long-term stress: sex and body temperature are major determinants in wild-living Alpine marmots

Hair cortisol concentration (HCC) has recently gained popularity as an easy-to-measure biomarker of long-term stress in wild and domestic animals. Hair integrates cortisol over long time periods within a single sample and it can be collected non-invasively, which makes its use particularly interesting for wildlife studies. Interpreting HCC values, however, is challenging, because they are determined by the interplay of multiple factors. Here, were explore potential determinants of HCC in the Alpine marmot Marmota marmota. We tested the relationship of sex, age class, physical condition and body temperature with the hair cortisol concentration of free-ranging marmots. We found marked sex difference in HCC, with higher levels in females. This might be related to sex-specific variation in social stress or resulting from physiological difference, e.g., in baseline and stress-induced levels of cortisol secretion. Interestingly, body temperature was also positively related to HCC, possibly hinting at individual short- and long-term stress reactivity as part of coping styles. Although further work is needed to entangle possible mechanisms underlying the neuro-endocrinological modulation on HCC, our results emphasize that determinants such as sex and body temperature in Alpine marmots should be accounted for, when using HCC as marker of chronic stress.

Peer-led family-centred problem management plus for immigrants (PMP-I) for mental health promotion among immigrants in USA: protocol for a pilot, randomised controlled feasibility trial

INTRODUCTION

Research is needed to investigate preventive strategies to reduce mental health burden and assess effective implementation among immigrants. Problem management plus (PMP) is a low-intensity multicomponent psychological intervention developed by the World Health Organization (WHO) that trained laypeople can deliver. PMP has been adapted as a prevention intervention and developed as PMP for immigrants (PMP-I), including psychoeducation, problem-solving, behavioural activations and mind-body exercise, to address immigrants' multiple stressors. This pilot trial aims to assess the feasibility and acceptability of PMP-I and provide a preliminary estimate of the difference between PMP-I versus community support services pamphlets on the primary outcomes of interest (stress, anxiety and depressive symptoms) to inform the design of a large-scale intervention.

METHODS AND ANALYSIS

The feasibility and acceptability of PMP-I will be assessed by measuring recruitment, session attendance, retention rates, programme acceptability and the fidelity of intervention delivery. This pilot trial will test preliminary effects of PMP-I vs community support services pamphlets in a randomised controlled trial (N=232 participants from 116 families (2 members/family); 58 families randomised to condition intervention or control) on stress, anxiety and depressive symptoms (primary outcomes), chronic physiological stress assessed in hair cortisol (secondary outcomes), and coping, family conflict resolution, and social networking (targets), with assessment at baseline, postintervention and 3-month postintervention. Eligibility criteria for the primary study participants include Bhutanese ≥18 years resettled in Massachusetts with a score of ≤14 on the Patient Health Questionnaire-9. All family members will be invited to participate in the family-based intervention (one session/week for 5 weeks). Multilevel modelling will compare the longitudinal change in outcomes for each treatment arm.

ETHICS AND DISSEMINATION

The Institutional Review Board of the University of Massachusetts Amherst approved this study (Protocol: 1837). Written informed consent will be obtained from all participants. The study results will be used to inform the design of a large-scale intervention and will be disseminated in peer-reviewed journals and conferences.

TRIAL REGISTRATION NUMBER

NCT04453709.

Evaluation of hair cortisol as an indicator of long-term stress responses in dogs in an animal shelter and after subsequent adoption

Shelter dogs are exposed to a variety of stressors. Among non-invasive techniques, hair cortisol concentration (HCC) is suggested an easy to collect biomarker for giving insight into long-term stress responses. We evaluated HCC as an indicator of long-term cortisol responses in dogs in an animal shelter over different chronological time points during sheltering and after adoption. Hair samples were collected from the neck region following a shave/re-shave protocol of shelter dogs (total n = 52) at four different time periods: T1 intake at shelter (pre-shelter period, n = 51); T2 after 6 weeks in the shelter (n = 23); T3 6 weeks after adoption (n = 24); T4 6 months after adoption (n = 22). HCC at T2 was significantly higher than HCC at T1, T3 and T4 (effect of sample collection moment: F_3,41 = 12.78, p < 0.0001). The dog’s weight class, age class, sex, reason for admission, kennel history and melanin type also explained HCC variability. No significant difference in HCC was found between shelter dogs T1 and control pet dogs in their own homes (n = 20, one sample, t = − 1.24, p = 0.219). A significant but moderate positive correlation between HCC and urinary cortisol:creatinine ratios was found (т = 0.3, p < 0.001). As HCC increased in the shelter, the use of this non-invasive parameter appears a useful additional tool in dog welfare research.

A novel Wim Hof psychophysiological training program to reduce stress responses during an Antarctic expedition

Objective

The aim of this prospective observational study was to investigate the effects of a novel Wim Hof psychophysiological training program on stress responses and hormone release in healthy participants during an Antarctic expedition.

Methods

All members of an Antarctic expedition were included in the study. The participants were healthy volunteers allocated to an intervention group (n = 6) and a control group (n = 7). The intervention consisted of 8 weeks of Wim Hof training. The training program comprised three integrated parts: breathing exercises, cold exposure and meditation. Psychometric measures (the Beck Depression Inventory and the Trauma Symptom Checklist-40) and neuroendocrine measures (cortisol, melatonin) were assessed pre- and post-intervention.

Results

The results showed that the 8-week training program significantly reduced stress responses, as indicated by a reduction in depressive symptoms. A non-significant reduction in cortisol was also observed.

Conclusions

These data constitute preliminary findings indicating that the Wim Hof Method may positively affect stress symptoms and adaptability of the hormonal system to respond adequately to the circadian rhythm in healthy volunteers who participated in an Antarctic expedition.

Identification of chronic stress biomarkers in dairy cows

Stress in dairy herds can occur from multiple sources. When stress becomes chronic because of a long duration and inability of animals to adapt, it is likely to deeply affect the emotional state, health, immunity, fertility and milk production of cows. While assessing chronic stress in herds would be beneficial, no real consensus has emerged from the literature regarding the indicators of interest. The goal of this study was to compare and evaluate potential biomarkers for chronic stress after inducing stress over a 4-week period through severe overstocking, restricted access to feed and isolated unusual events. A total of 30 cows were involved in the experiment and two similar groups were constituted. Over a 4-week period, the 15 cows of the stress group were housed in overstocked conditions, with 4.6 m² per cow, including resting and feeding areas. In this area, only seven individual places at the feeding area were available for the 15 cows to generate competition for feed access. Twice during the trial and over a period of 2 h, an additional stress was induced by moving cows to an unfamiliar barn and diffusion of stressing noises (dog barking). Meanwhile, the 15 cows of the control group stayed in the original barn, with more than 10 m² per cow and more individual places at the feeding area than cow number. On a weekly basis, several variables considered as potential biomarkers for chronic stress were recorded. Collected data were analysed using single trait linear repeated mixed models. No differences were observed regarding milk yield, BW of cows or body condition score but the milk loss was more pronounced in the stress group. The activity was more heterogeneous and the rumination of cows was lower in the stress group. The heart rate was lower in the stress group and showed more heterogeneity at the end of the stress period. No differences were observed regarding salivary cortisol, blood glucose, β-endorphin, thyroxine and leucocyte profile. A higher level of hair cortisol and blood fructosamine were observed in the stress group at the end of the stress period. Regarding the practical use of the highlighted biomarkers, milk loss may be an effective and easy way to detect general problems, including stress. The blood fructosamine and the hair cortisol concentrations are promising indicators to assess chronic stress in commercial farms.

Psychosocial Stress, Epileptic-Like Symptoms and Psychotic Experiences

Background

Current research suggests that stressful life experiences and situations create a substantive effect in the development of the initial manifestations of psychotic disorders and may influence temporo-limbic epileptic-like activity manifesting as cognitive and affective seizure-like symptoms in non-epileptic conditions.

Methods

The current study assessed trauma history, hair cortisol levels, epileptic-like manifestations and other psychopathological symptoms in 56 drug naive adult young women experiencing their initial occurrence of psychosis.

Results

Hair cortisol levels among patients experiencing their initial episode of psychosis, were significantly correlated with stress symptoms measured by Trauma Symptom Checklist-40 (r = − 0.48, p < 0.01), and complex partial seizure-like symptoms measured by the Complex Partial Seizure-Like Symptoms Inventory (r = − 0.33, p < 0.05) and LSCL-33 (r = − 0.33, p < 0.05). Hair cortisol levels were not found to be significantly correlated with symptoms of anxiety and depression measured by Beck depression Inventory and Zung Anxiety Scale.

Conclusion

These findings suggest a significant relationship between epileptic-like symptoms and stress responses demonstrated by patients in their first psychotic episode. These findings may suggest the potential for research to explore usefulness of anticonvulsant treatment in patients who do not respond to usual psychotropic medication.

Risk Factors for Chronic Stress in Sows Housed in Groups, and Associated Risks of Prenatal Stress in Their Offspring

Chronic stress has a detrimental effect on sow welfare and productivity, as well as on the welfare and resilience of their piglets, mediated prenatally. Despite this, the specific risk factors for chronic stress in pregnant sows are understudied. Group-housed pregnant sows continuously face numerous challenges associated with aspects of the physical (group type and size, flooring, feeding system) and social (stocking density, mixing strategy) environment. There are many well-known potent stressors for pigs that likely contribute to chronic, physiological stress, including overcrowding, hot temperatures, feed restriction, inability to forage, uncomfortable floors, and poor handling. Some of these stressors also contribute to the development of production diseases such as lameness, which in turn are also likely causes of chronic stress because of the associated pain and difficulty accessing resources. The aim of this review is to discuss potential risk factors for chronic stress in pregnant sows such as space allowance, group size and type (stable/dynamic), feeding level, lameness, pen design, feed system, enrichment and rooting material, floor type, the quality of stockmanship, environmental conditions, and individual sow factors. The mechanisms of action of both chronic and prenatal stress, as well as the effects of the latter on offspring are also discussed. Gaps in existing research and recommendations for future work are outlined.

Hair cortisol concentration reflects the life cycle and management of grey wolves across four European populations

The grey wolf (Canis lupus) persists in a variety of human-dominated landscapes and is subjected to various legal management regimes throughout Europe. Our aim was to assess the effects of intrinsic and methodological determinants on the hair cortisol concentration (HCC) of wolves from four European populations under different legal management. We determined HCC by an enzyme-linked immune assay in 259 hair samples of 133 wolves from the Iberian, Alpine, Dinaric-Balkan, and Scandinavian populations. The HCC showed significant differences between body regions. Mean HCC in lumbar guard hair was 11.6 ± 9.7 pg/mg (range 1.6–108.8 pg/mg). Wolves from the Dinaric-Balkan and Scandinavian populations showed significantly higher HCC than Iberian wolves, suggesting that harvest policies could reflected in the level of chronic stress. A significant negative relationship with body size was found. The seasonal, sex and age patterns are consistent with other studies, supporting HCC as a biomarker of chronic stress in wolves for a retrospective time frame of several weeks. Our results highlight the need for standardization of sampling and analytical techniques to ensure the value of HCC in informing management at a continental scale.

A mindfulness-based stress management program for caregivers of allogeneic hematopoietic stem cell transplant (HCT) patients: Protocol for a randomized controlled trial

Objectives

Caregivers of allogeneic hematopoietic stem cell transplant (HCT) cancer patients experience high caregiver burden and carry a significant amount of responsibility. Mindfulness has the potential to lessen caregiver burden by aiding in stress management. To date, no studies have examined the efficacy of mindfulness in reducing caregiver burden in this population. Based on our pilot study demonstrating initial feasibility and acceptability of FOCUS (Focusing On mindfulness for Caregivers Under Stress), this 3-arm randomized controlled trial aims to examine the efficacy of a 6-week mindfulness-based stress management program for allogeneic HCT caregivers. Hypotheses include that the FOCUS condition will have lower post-treatment caregiver burden and that patients of these caregivers will have better patient health outcomes compared to other treatment conditions.

Method

Eligible caregivers will be randomly assigned to one of three treatment conditions: FOCUS, Healthy Living (HL; active control), and Enhanced Care (EC; usual care). Caregivers in FOCUS and HL will participate in 6-week weekly individual treatment sessions and will be sent brief daily momentary interventions/messages. Caregivers in all conditions will complete daily diaries over the course of treatment. Patients of enrolled caregivers will be enrolled for assessments only. Participants will complete assessments at baseline, end of treatment, 2- and 6-months post-treatment. Biomarker data will be collected via hair cortisol concentrations from caregivers at baseline and 6 months post-treatment.

Results

Recruitment is ongoing.

Conclusions

The data collected from this study will provide evidence on the efficacy of mindfulness in alleviating HCT caregiver stress and impacting patient health outcomes.

Trial registration

The current study is registered in clinicaltrials.gov (NCT05078229); see https://clinicaltrials.gov/ct2/show/NCT05078229?term=christine+vinci&draw=2&rank=1.

Hair cortisol change at COVID-19 pandemic onset predicts burnout among health personnel

BACKGROUND

The COVID-19 pandemic has put chronic pressure on worldwide healthcare systems. While the literature regarding the prevalence of psychological distress and associated risk factors among healthcare workers facing COVID-19 has exploded, biological variables have been mostly overlooked.

METHODS

467 healthcare workers from Quebec, Canada, answered an electronic survey covering various risk factors and mental health outcomes three months after the onset of the COVID-19 pandemic. Of them, 372 (80%) provided a hair sample, providing a history of cortisol secretion for the three months preceding and following the pandemic's start. We used multivariable regression models and a receiver operating characteristic curve to study hair cortisol as a predictor of burnout and psychological health, together with individual, occupational, social, and organizational factors.

RESULTS

As expected, hair cortisol levels increased after the start of the pandemic, with a median relative change of 29% (IQR = 3-59%, p < 0.0001). There was a significant association between burnout status and change in cortisol, with participants in the second quarter of change having lower odds of burnout. No association was found between cortisol change and post-traumatic stress disorder, anxiety, and depression symptoms. Adding cortisol to individual-occupational-socio-organizational factors noticeably enhanced our burnout logistic regression model's predictability.

CONCLUSION

Change in hair cortisol levels predicted burnout at three months in health personnel at the onset of the COVID-19 pandemic. This non-invasive biological marker of the stress response could be used in further clinical or research initiatives to screen high-risk individuals to prevent and control burnout in health personnel facing an important stressor.