BACKGROUND: The risk of preterm birth (PTB) increases when experiencing stress during pregnancy. Chronic stress has been associated with a dysregulation of the hypothalamic-pituitary-adrenal axis, for which hair cortisol concentration (HCC) is a promising biomarker. However, previous studies on the association between HCC and PTB yielded inconsistent results. This systematic review and meta-analysis synthesized previous studies on the association between maternal HCC before and during pregnancy and spontaneous PTB.
METHODS: Data was extracted from N = 11 studies with k = 19 effect sizes retrieved from PubMed, Embase, Web of Science, CINAHL and citation searching by hand in June 2023 and updated in October 2023. Standardized mean differences were calculated, and a random-effects three-level meta-analysis was conducted. Effect heterogeneity was assessed using Q and I2.
RESULTS: HCC during pregnancy was higher among PTB than term groups, but effects were not statistically significant (z = 0.11, 95% CI: - 0.28, 0.51, p = .54) and total heterogeneity was high (Q16 = 60.01, p < .001, I2Total = 92.30%). After leaving out two possible outlier studies in sensitivity analyses, HCC was lower among preterm compared to term delivering groups, although not statistically significant (z = - 0.06, 95% CI: - 0.20, 0.08, p = .39) but with a substantially reduced total heterogeneity (Q12 = 16.45, p = .17, I2Total = 42.15%). No moderators affected the estimates significantly, but an effect of trimester and gestational age at delivery is likely.
CONCLUSIONS: There is currently no evidence of prenatal HCC differences between PTB and term groups as effects were small, imprecise, and not significant. Low statistical power and methodological weaknesses of the small-scale studies challenge possible biological inferences from the small effects, but further research on HCC during pregnancy is highly encouraged.

Higher prevalence of depression in females might be associated with sex-specific cortisol levels. Evidence exists that cortisol levels differ between healthy females and males, however a sex-specific association in depression has not been systematically assessed. Thus, the current study quantifies the existing literature on different cortisol parameters, i.e., basal cortisol, hair cortisol, cortisol awakening response (CAR), and cortisol stress reactivity comparing depressed females and males as well as sex-specific comparisons with healthy controls. Following an extensive literature research, fifty original articles were included. Depressed females had significantly higher hair cortisol, higher CAR, and lower cortisol stress reactivity compared to depressed males. In comparison with sex-matched controls, female patients had significantly higher evening basal cortisol, higher CAR and lower cortisol stress reactivity, and male patients had significantly higher general, morning and evening basal cortisol. Overall, sex as a fundamental driver of cortisol levels in depression needs to be taken into account.

UNASSIGNED: Studies measuring hair cortisol concentration (HCC) have been increasingly conducted to document stress-related, endocrine changes aggregated over time. Previous studies have shown that HCC reflects abnormalities in the hypothalamic-pituitary-adrenocortical axis (HPA axis) in the context of somatic diseases, such as Cushing\'s syndrome. HCC variations also reveal a corresponding alteration in HPA-axis-function in mental disorders, highlighting its potential role as a biomarker for interventions targeting mental health problems.
UNASSIGNED: The aim of this study was to investigate the role of HCC in various psychological and neuropsychiatric interventions and to explore the extent to which HCC can serve as a predictive or outcome parameter in such interventions by conducting a PRISMA-compliant review of the literature.
UNASSIGNED: From May to July 2022, the databases Web of Science, Google Scholar, PsychINFO, and ResearchGate were systematically searched using different combinations of relevant keywords. Studies of different types that examined HCC in the context of a wide range of psychological and neuropsychiatric interventions were included. Studies in languages other than English or German and animal studies were excluded. The MMAT tool was used, to assesses the Risk of bias.
UNASSIGNED: The initial search identified 334 studies. After applying the inclusion and exclusion criteria, 14 publications with a total number of 1,916 participants were identified. An association between HCC and PTSD, depressive disorders, and ongoing social and family stress can be documented. The effect of relaxation techniques, mental training, CBT, or PTSD therapy on HCC has been studied with equivocal results. Some studies found decreased HCC after treatment, while others did not show a clear effect. Baseline HCC appears to be of particular importance. In some studies, higher baseline HCC was associated with increased treatment response, providing a predictive value for HCC.
UNASSIGNED: HCC is increasingly being used as a biomarker for the mapping of psychological and neuropsychiatric interventions. However, due to the wide range of study populations and interventions, results are still heterogeneous. Nevertheless, HCC seems to be an encouraging biological parameter to describe the trajectory of different interventions aimed at improving mental health.

BACKGROUND: Cortisol is one of the most extensively studied biomarkers in the context of trauma/posttraumatic stress disorder (PTSD). For more than a decade, hair cortisol concentrations (HCC) have been measured in this context, leading to a two-staged dysregulation model. Specifically, an elevated secretion during/immediately after trauma exposure eventually reverts to hyposecretion with increasing time since trauma exposure has been postulated.
OBJECTIVE: The aim of our systematic review was to re-evaluate the two-staged secretion model with regard to the accumulated diagnostic, prognostic, and intervention-related evidence of HCC in lifetime trauma exposure and PTSD. Further, we provide an overview of open questions, particularly with respect to reporting standards and quality criteria.
METHODS: A systematic literature search yielded 5,046 records, of which 31 studies were included.
RESULTS: For recent/ongoing (traumatic) stress, the predictions of cortisol hypersecretion could be largely confirmed. However, for the assumed hyposecretion temporally more distal to trauma exposure, the results are more ambiguous. As most studies did not report holistic overviews of trauma history and confounding influences, this may largely be attributable to methodological limitations. Data on the prognostic and intervention-related benefits of HCC remain sparse.
CONCLUSIONS: Over the last decade, important insights could be gained about long-term cortisol secretion patterns following lifetime trauma exposure and PTSD. This systematic review integrates these insights into an updated secretion model for trauma/PTSD. We conclude with recommendations for improving HCC research in the context of trauma/PTSD in order to answer the remaining open questions.

Childhood obesity has been linked to physical and psychological comorbidities that can be carried into adulthood. A bidirectional link between body weight and the stress system appears to exist, as cortisol may affect the regulation of appetite, while adiposity can affect cortisol secretion. Among the biological tissues used to evaluate cortisol concentrations, scalp hair can provide retrospective measures. The aim of this systematic review was to investigate the difference in hair cortisol concentrations between obese and non-obese minors ≤ 19 years of age. Children and adolescents with genetic, somatic or psychiatric comorbidities were excluded. The work was conducted following the PRISMA guidelines, using prespecified search terms in the Pubmed database. The initial search yielded 56 studies, while the last step of the screening procedure concluded in 9 observational studies. Among them, the results could be characterized as inconclusive. Five of them demonstrated significantly higher hair cortisol concentrations in obese children and adolescents than normal weight subjects. On the contrary, the remaining four found no statistically significant differences in hair cortisol concentrations between obese and non-obese subjects. Different methodologies applied, and confounding factors could explain the inconsistency in the findings. Further research is needed to provide more solid results.

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.

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

Literature supports a causal role of stress in major depressive disorder (MDD). Hair cortisol concentration (HCC) has been widely used as a measure of long-term stress. Although elevated HCC has been observed in healthy people experiencing chronic stress, findings regarding individuals with mental disorders have been complicated. This review attempts to systematically present all the published research on major depression and HCC. An extensive search of databases was performed to identify articles that investigated this question. The initial search retrieved 142 studies, of which, 16 original articles were included in this review. Results were contradictory; most of the studies showed no significant HCC differences between MDD patients and controls, while others indicated either higher or lower HCC in MDD patients than controls. Higher HCC was reported in first depressive episode compared to recurrent MDD and controls; patients with comorbid MDD and anxiety disorder had higher HCC than controls. No significant HCC difference was found between patients with melancholic or atypical depression and controls. Findings concerning HCC in postpartum depression were inconsistent. A meta-analysis of the data extracted from seven studies of the sample was performed to quantify the degree of cortisol change in MDD patients vs. controls. A random effects model revealed no significant hair cortisol concentrations difference between depressed patients and healthy controls (SMD: -0.02, 95% CI: -0.36 to 0.32). Significant heterogeneity was identified across included studies (P = 0.002, I2 = 71%). The disagreement among studies\' results indicates that there is room for improvement in this research field. Confounding factors independent of depression should be taken into consideration.

The current body of research lacks a meta-analysis of the relationship between hair cortisol concentration (HCC) and anthropometry in children. Therefore, this systematic review and meta-analysis was conducted to examine this relationship and explore possible moderators between HCC and body mass index (BMI/BMI z-score). Eleven databases were searched: CINAHL, Cochrane, Embase, PsycEXTRA, Psychology and Behavioral Sciences, PsycINFO, PubMed, Scopus, Social Sciences Full Text, Sociological Abstracts and Web of Sciences. Random-effects models and exploratory moderator analyses with mixed-effects models were performed using the Comprehensive Meta-Analysis software. The meta-analysis showed small positive correlations between HCC and BMI (r = 0.08, 95% confidence interval [CI]: 0.02, 0.14, n = 18, p = .009), BMI z-score (r = 0.10, 95% CI: 0.03, 0.16, n = 12, p = .003), waist circumference (r = 0.10, 95% CI: 0.04, 0.17, n = 10, p = .001) and body fat including fat mass index (r = 0.06, 95% CI: 0.02, 0.11, n = 3, p = .005). The relationship between HCC and BMI/BMI z-score was significantly moderated by children\'s sex. Results from this meta-analysis provide initial objective support for a small positive relationship between HCC and anthropometric factors.

The diagnosis of endogenous Cushing syndrome is often challenging and requires multiple repeated blood, urine, and saliva tests to detect elevated cortisol levels. Hair cortisol concentration has been described as a marker of long-term exposure to systemic cortisol in patients with Cushing syndrome. Like hemoglobin A1c is used to detect serum glucose exposure over months, segmental hair cortisol can help identify patients with milder forms of and/or periodic or cyclical Cushing syndrome, which may reduce time and costs associated with collection of urine, salivary, and serum cortisol.
Success of hair cortisol in detection of Cushing syndrome will be discussed in context of current literature, including differences between total or segmental hair cortisol in accurately determining timeline of cortisol exposure. Optimal methods of hair collection, storage, processing, and analysis and efforts toward standardization will be a major focus.
Recent evidence suggests increased sensitivity and specificity of hair cortisol in detecting Cushing syndrome. Future guidelines should consider this test as a routine part of the repertoire of screening tests for Cushing syndrome. Possible confounders to explain discrepant results in the literature will be discussed.