Investigating relations among stress, sleep and nail cortisol and DHEA

Refugee health and physiological profiles in transitional settlements in Serbia and Kenya: Comparative evidence for effects of gender and social support

When armed conflict compels people to flee from their homelands, they embark on protracted journeys during which they experience wide ranging physical, social, and psychological challenges. Few studies have focused on refugee psychosocial and physiological profiles during the transitional phase of forced migration that often involves temporary sheltering. Transient refugees' experiences can vary substantially based on local socio-ecological conditions in temporary settlements, including the length of stay, living conditions, as well as the availability and accessibility of physical and social resources. In this study, we compared physiological and psychosocial data from refugees (N=365; 406 observations) in Serbia and Kenya, respectively, with divergent temporal (length of stay) and socio-ecological conditions. In Serbia, refugees resided in asylum centers (mean stay: 0.9 y); in Kenya they were living in Kakuma Refugee Camp (mean stay: 8.8 y), one of the world's largest camps at the time. We had limited ability to directly compare psychosocial measures and used meta-analytic techniques to evaluate predictors of refugee mental and physical health at the two sites, including based on perceived social support. Refugees in Serbia had higher fingernail cortisol (p < 0.001) and were less likely to have elevated C-reactive protein (CRP) levels (p < 0.01) than refugees in Kakuma. We found common gender differences in both settings; women had lower cortisol but higher EBV antibody titers and higher likelihood of having elevated CRP compared to men (all p < 0.01). Woman also reported poorer mental and physical health (p < 0.001). These physiological and health differences may reflect variation between men and women in their psychosocial and physical experiences of factors such as stress, violence, and trauma during their journeys and as transitional refugees. Finally, we also found that refugees with lower levels of perceived social support reported poorer physical and mental health (p < 0.001). Although our results are cross-sectional, they suggest that this intermittent phase of the refugee experience is a key window for helping enhance refugee well-being through an emphasis on interpersonal and community support systems.

Exposome Impact on Nail Health

Background

The nail unit is a complex system with various components, each serving distinct functions. The exposome, encompassing external and internal factors such as UV radiation, air pollution, dietary habits, and cosmetic product usage, substantially influences nail health and can lead to premature nail aging.

Summary

Internal and external exposomal factors can impact differently on nail health, inducing a variety of different clinical conditions. Effective therapeutic strategies exist, but a comprehensive understanding of how the exposome affects nails is lacking. This article aims to bridge this knowledge gap by exploring the relationship between the exposome and nail health, emphasizing it as a central focus of our analysis.

Key Messages

(1) The exposome, comprising various external and internal factors, may significantly influence nail health negatively, leading to premature nail aging. (2) Different nail conditions may arise due to the exposomal influence on nails. (3) Understanding the exposome's impact on nail health is crucial for developing solutions to mitigate negative effects and improve overall nail well-being.

Cortisol and changes in depressive symptoms: The moderating role of DHEA

Stress is associated with activation of the hypothalamus-adrenal-axis (HPA). Cortisol, a product of the HPA, is thought to predict depression. However, to date, the majority of studies investigating the cortisol-depression relationship have been cross-sectional and results have been mixed. One possible reason for these mixed findings, may be that many studies fail to consider the moderating role of dehydroepiandosterone (DHEA), which is released alongside cortisol and is thought to serve opposing functions. Therefore, the present study investigated the main and interactive effects of cortisol and DHEA on depressive symptoms. Salivary cortisol and DHEA were measured from saliva throughout the Trier Social Stress task for N = 417 participants at baseline. Participants reported on their depressive symptoms using the Beck Depression Inventory - II at both baseline and follow up (ranging from 1-20 months post baseline; M = 11.60, SD = 5.80) as well as general demographics. The lavaan package in R (version 0.6.11; Rosseel, 2012) was used to conduct multiple regression analyses with FIML to explore the relationships between these variables. Results demonstrated no main effect of cortisol or DHEA, but did show a significant interaction with DHEA. The relations between cortisol and depressive symptoms depended on levels of DHEA such that the relationship was positive at low and negative at high levels of DHEA, with the overall interaction significant (β = -.22, p < .001, 95% CI = [-.333, -.115]). DHEA can act as a protective factor against depression when cortisol levels are high. This presents opportunities for future research on how to improve DHEA levels to potentially reduce depression.

Time-course changes in fingernail cortisol levels during pregnancy and postpartum

The cortisol level in fingernails can reflect the cumulative hormones produced in the body several months prior. However, previous studies have only demonstrated the cross-sectional associations of fingernail cortisol with salivary or hair cortisol, and not longitudinal changes in fingernail cortisol in situations where cortisol levels in the body could be expected to change. Therefore, this study focused on pregnancy as a model for changes in cortisol levels over a prolonged period of time, and investigating the time courses of fingernail cortisol during pregnancy and the postpartum period. We collected nail samples from 30 healthy women during pregnancy and 12 months postpartum to measure the cortisol levels in the nail. Results showed that cortisol levels in fingernail clippings increased from 1 month before childbirth to 4 months postpartum, with the levels peaking at 2 months postpartum. Additionally, we found higher cortisol levels in fingernail clippings in primiparas than in those of multiparas. The time course of fingernail cortisol levels could replicate the longitudinal changes in cortisol in the body, and differences between multiparas and primiparas seemed to be biologically plausible, which could support the concept of fingernail cortisol as a retrospective index of hormone production.

Determination of well-being-related markers in nails by liquid chromatography tandem mass spectrometry

Well-being is a multifactorial positive state that is highly influenced by some endogenous molecules that control happiness and euphoric feelings. These molecules, e.g., neurotransmitters, hormones and their derivatives, play a crucial role in metabolism and may be referred to as "well-being-related markers". The deregulation of well-being-related markers can lead to organism malfunctions and life-threatening states. In this research, we aimed to evaluate the potential of nails for the chronic production of several well-being-related markers. For this purpose, we developed an LCMS /MS-based method for the determination of 10 well-being-related markers, including melatonin, serotonin, cortisol, kynurenine and several precursors and metabolites. The method was optimized regarding different analytical steps: required sample amount, extraction time, number of required extractions, preconcentration, injection volume and MS conditions. Method validation was performed by two different approaches: (i) using surrogate nail matrix and (ii) using authentic nail samples by standard additions. The method was found to be linear in the expected endogenous range and sensitive enough to determine the low endogenous concentration levels in nails. Accuracy and precision were appropriate in both validation approaches. As proof of concept, the method was used (i) to correlate fingernail and toenail levels for all metabolites in 22 volunteers, (ii) to establish the endogenous concentration range of all metabolites in females (n = 50) and males (n = 34) and (iii) to correlate the metabolite levels with age. For some metabolites, the calculated ranges have been reported for the first time. In summary, the present strategy to evaluate well-being-related markers in nails may be a useful tool for the evaluation of the production of these important compounds with high potential for a wide range of clinical purposes.

Serum metabolomics study of narcolepsy type 1 based on ultra-performance liquid chromatography-tandem mass spectrometry

Narcolepsy is a chronic and underrecognized sleep disorder characterized by excessive daytime sleepiness and cataplexy. Furthermore, narcolepsy type 1 (NT1) has serious negative impacts on an individual's health, society, and the economy. Currently, many sleep centers lack the means to measure orexin levels in the cerebrospinal fluid. We aimed to analyze the characteristics of metabolite changes in patients with NT1, measured by ultra-performance liquid chromatography-tandem mass spectrometry. A principal component analysis (PCA), an orthogonal partial least square discriminant analysis (OPLS-DA), t tests, and volcano plots were used to construct a model of abnormal metabolic pathways in narcolepsy. We identified molecular changes in serum specimens from narcolepsy patients and compared them with control groups, including dehydroepiandrosterone, epinephrine, N-methyl-D-aspartic acid, and other metabolites, based on an OPLS-loading plot analysis. Nine metabolites yielded an area under the receiver operating curve > 0.75. Meanwhile, seven abnormal metabolic pathways were correlated with differential metabolites, such as metabolic pathways; neuroactive ligand‒receptor interaction; and glycine, serine, and threonine metabolism. To our knowledge, this is the first study to reveal the characteristic metabolite changes in sera from NT1 patients for the selection of potential blood biomarkers and the elucidation of NT1 pathogenesis.

Peripubertal Testosterone, 17β-Estradiol and Progesterone Concentrations in Hair and Nails in Dobermann Dogs

Studies about puberty in dogs are few, probably because many factors are involved in the delicate process of puberty onset, leading to difficulties in the proper enrollment of subjects. Moreover, the use of blood for monitoring hormonal changes can be problematic, and not feasible for long-term studies. Hair and nails proved to be suitable matrices for the retrospective evaluation of hormones' long-term accumulation. This study was performed using hair and nails for the evaluation of testosterone (T), 17β-estradiol (E2) and progesterone (P4) concentrations to assess possible sexual steroid changes during the peripubertal period in dogs. The results, obtained on five males and five females, showed a significant increase in T in hair and nails of males immediately before puberty. In females, a significant increase in E2 at puberty and a marked increase in P4 after puberty was found in both biological specimens. Sex-related differences were detected only for T hair concentrations, but when the sex and sampling time were considered together, hair and nails T and nails P4 concentrations allowed us to discern between male and female dogs at specific sampling times. The results from this study showed that hair and nails are useful biological specimens for the retrospective evaluation of changes in T, E2 and P4 concentrations in peripubertal dogs.

Measuring Adolescent Chronic Stress: A Review of Established Biomarkers and Psychometric Instruments

Adolescence is a period of stressful physiological and psychosocial changes. Exposure to chronic stress can cause specific structural and functional changes in an organism, which can be appraised objectively. Some of these alterations are an expected reaction of the body in its attempt to adapt to a stressful situation, while others are signs of possible disease development. The aim of this review was to present the most widely used methods of stress evaluation in adolescence research. Primary biomarkers associated with different biological systems, such as the stress hormones glucocorticoids, and catecholamines, as well as the available methods of extraction and assessment of each biomarker, are presented. This work also includes secondary outcomes, which can also provide an estimation of an individual's stress level. Also, most available psychometric instruments of stress, constructed to address specifically this period of life, are presented and discussed. In addition, this paper addresses possible confounding factors that may affect stress measurements, which should be taken under consideration when conducting stress research. To objectively evaluate stress, it is of great importance for a researcher to be familiar with the condition under examination and its representative stress indices. Adequate evaluation of adolescents with the selection of proper psychometric tests and biological markers can help design targeted interventions aiming to prevent or reverse the effects of physical and mental stressors that occur during adolescence, effects that can be carried into adulthood with detrimental consequences.

Coat, Claw and Dewclaw 17-β-Estradiol and Testosterone Concentrations in Male and Female Postpubertal Cats: Preliminary Results

In the recent past, tissue materials such as hair/coat and nails/claws have proved to be useful for the study of long-term hormonal changes in humans and animals and shown to be advantageous in terms of being collectable without invasiveness, with a benefit in terms of animal welfare. However, studies using these tissue materials in cats are scarce, especially on sexual hormone measurement. In this study, the concentrations of 17-β-estradiol (E2) and testosterone (T) were assessed in 20 male and 18 female domestic postpubertal cats at the time of neutering/spaying during the breeding season. Hormones were measured in coat shaved from the forearm (ACOAT) and from the surgical area (SCOAT); claws were collected from the forearms (CLAWS) and the dewclaws (DCLAWS). Although all these tissue materials were shown to be useful for E2 and T long-term measurement, only T concentrations were higher (p < 0.001) in males from both ACOAT and SCOAT samples when compared to females and therefore useful for distinguishing between the two sexes. Within each sex, E2 and T concentrations can be assessed on coat, but also on the dewclaws, providing an alternative, practical, matrix for sexual steroid measurement in postpubertal cats during the breeding season.

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.

Transient refugees' social support, mental health, and physiological markers: Evidence from Serbian asylum centers

OBJECTIVES

Refugees seeking safety across international borders are often exposed to a wide breadth of psychosocially stressful experiences that may fracture existing sources of social support and impair the generation of new social relationships, with implications for their long-term health and resilience. Using data from recently settled refugees in two asylum centers in Serbia, we examined the associations between social support, mental health, and physiological markers.

METHODS

In this mixed-method study of refugees (age 18-50 years, n = 76), we collected key socio-demographic information and conducted semi-structured interviews about refugees' journey and stay in Serbia, trauma/loss, and their sources of social support. We also collected self-reported measures of mental well-being as well as physiological markers relevant to repeated exposure to chronic psychosocial stress (fingernail cortisol and dried blood spots for analysis of Epstein-Barr virus [EBV] antibody titers).

RESULTS

We found that refugees with longer journeys reported lower social support than those with shorter journeys. Refugees with lower social support reported poorer mental well-being, greater PTSD-related symptoms, and higher recent perceived stress than those with higher social support. We also observed that refugees with lower social support and higher recent stress, respectively, tended to exhibit higher fingernail cortisol levels. However, we did not observe comparable patterns linking EBV antibodies with psychosocial functioning.

CONCLUSION

Our cross-sectional findings are consistent with the notion that social support is likely to be a critical component in effective interventions aimed at mitigating the adverse health effects of relocation-related illnesses and poor social functioning as they await resettlement.

Higher Levels of Stress-Related Hair Steroid Hormones Are Associated with the Increased SCORE2 Risk Prediction Algorithm in Apparently Healthy Women

Cardiovascular diseases (CVDs) are the major cause of death worldwide. Although the importance of conventional CVD risk factors, including older age, male gender, hypertension, obesity, dyslipidemia and hyperglycemia, is well-studied, psychosocial stress, which is considered an independent CVD risk factor, requires further investigation. Thus, we aimed to investigate the association between long-term secretion of stress-related steroid hormones, including cortisol, cortisone and dehydroepiandrosterone, and the 10-year fatal and non-fatal CVD risk estimated by the SCORE2 risk prediction algorithm, as well as traditional CVD risk factors in a group of apparently healthy women. A total of 145 women (aged 50–64 years) participating in the national CVD prevention program were enrolled in the study. Sociodemographic, lifestyle, health-related characteristics, stress, anxiety and sleep quality indicators were evaluated using specific questionnaires. Anthropometric and arterial blood pressure measures were assessed by trained personnel, lipid and glucose metabolism biomarkers were measured using routine methods, and hair steroid hormone levels were determined by ultra-high-performance liquid chromatography-tandem mass spectrometry. The results showed that higher levels of hair cortisol and cortisone are associated with increased SCORE2 values. Moreover, significant associations between hair glucocorticoids and individual cardiovascular risk factors, including obesity, hypertension, dyslipidemia and hyperglycemia, were found. These findings indicate that stress-related hair steroid hormones might be valuable biomarkers for CVD prediction and prevention.

A validation study on fingernail cortisol: correlations with one-month cortisol levels estimated by hair and saliva samples

Several studies have focused on the cortisol levels in fingernail samples as a possible index of cumulative hormone production; however, the biological validity of fingernail cortisol has not been fully established. We investigated the association between cortisol levels in fingernail samples and other biological specimens, including hair and saliva samples, in healthy young adults to determine whether fingernail cortisol was associated with past cumulative hormone production. Participants were 23 adults (14 men and 9 women; mean age = 22.7 ± 2.8 years). Saliva samples were collected three times per day for 30 days, and hair samples (1 cm) from participants' scalps were obtained. Fingernail samples were repeatedly collected for 8 months, considering growth rate of fingernail and time lag for fingernails to fully extend from the nail matrix. Cortisol levels in hair samples were significantly associated with the levels in fingernail samples that were obtained 3 months after hair collection (r = .48, p < .05). The 30-day integrated area under the curve, based on salivary cortisol levels at awakening and bedtime, were significantly associated with cortisol levels in fingernail samples that were collected 2-5 months after saliva collection. This finding was especially significant after adjusting for the awakening time when the saliva was collected. This study provided evidence that fingernail cortisol was associated with cumulative hormone levels measured several months before but not those in the present. The samples may be useful for endocrinological evaluation in the investigation of chronic stress, cortisol levels, and health; moreover, the use of fingernail samples would permit larger-scale studies.

Children's fingernail cortisol among BaYaka foragers of the Congo Basin: associations with fathers' roles

Children and mothers' cortisol production in response to family psychosocial conditions, including parenting demands, family resource availability and parental conflict, has been extensively studied in the United States and Europe. Less is known about how such family dynamics relate to family members' cortisol in societies with a strong cultural emphasis on cooperative caregiving. We studied a cumulative indicator of cortisol production, measured from fingernails, among BaYaka forager children (77 samples, n = 48 individuals) and their parents (78 samples, n = 49) in the Congo Basin. Men ranked one another according to locally valued roles for fathers, including providing resources for the family, sharing resources in the community and engaging in less marital conflict. Children had higher cortisol if their parents were ranked as having greater parental conflict, and their fathers were seen as less effective providers and less generous sharers of resources in the community. Children with lower triceps skinfold thickness (an indicator of energetic condition) also had higher cortisol. Parental cortisol was not significantly correlated to men's fathering rankings, including parental conflict. Our results indicate that even in a society in which caregiving is highly cooperative, children's cortisol production was nonetheless correlated to parental conflict as well as variation in locally defined fathering quality. This article is part of the theme issue 'Multidisciplinary perspectives on social support and maternal-child health'.

Sleep and self-control: A systematic review and meta-analysis

Controlling impulses and overcoming temptations (i.e., self-control) are key aspects of living a productive life. There is a growing yet disperse literature indicating that sleep is an important predictor of self-control. The goal of this meta-analysis is to empirically integrate the findings from multiple literatures, and investigate whether sleep quality, and sleep duration predict self-control. To provide a thorough understanding of the proposed relationships, this meta-analysis also investigated potential differences between the level of analysis (between-individual vs. within-individual), research design (experiment vs. correlation; and cross-sectional vs. time-lagged), and types of measure (subjective vs. objective for sleep and self-control). A systematic review was conducted through ABI/Inform (including PsycInfo), ERIC, ProQuest Dissertation & Theses, PubMed, and Psychology Database using keywords related to self-control and sleep. Sixty-one independent studies met the inclusion criteria. The results, in general, suggest that sleep quality (between-individual 0.26, CI 0.21; 0.31; and within-individual 0.35, CI 0.24; 0.45), and sleep duration (between-individual 0.14, CI 0.07; 0.21; and within-individual 0.20, CI 0.09; 0.31) are all related to self-control. Given the impact of self-control on how individuals live productive lives, a future research agenda should include a deeper investigation in the causal process (potentially via prefrontal cortex activity) linking sleep and self-control, and an examination of the moderators (individual and contextual variables) that could impact the relationship between sleep and self-control.

Human nail cortisol as a retrospective biomarker of chronic stress: A systematic review

Cortisol is the primary glucocorticoid produced by the activation of the hypothalamic pituitary adrenal (HPA) axis after a psychological or physiological stressor. The dysregulation of the HPA axis by chronic stress has been associated with psychiatric disorders. Although hair is currently the main validated source of chronic cortisol concentrations, cortisol is also bound to human nails, another keratinised matrix. Therefore, nail cortisol has the potential to be an alternative retrospective chronic measure of HPA activation. The aim of this systematic review was to assess the temporal resolution, methodological issues, HPA correlates, and target populations in nail cortisol investigations. A qualitative synthesis was performed to assess current literature exploring cortisol concentrations from human nails. A total of 18 eligible human studies extracted from Medline (PubMed and Ovid), ProQuest (PsycINFO), and Scopus found that immunoassays and mass spectrometry were the two primarily methods of analysis. However, methodological variability remained evident between studies. Nail cortisol correlated with saliva and hair in some studies and was investigated across multiple developmental periods. Finally, when applied as an outcome measure in health disorders, higher nail cortisol concentrations have been shown to be associated with acute coronary syndrome and depression. In conclusion, nail cortisol may serve as a retrospective biomarker of chronic stress; however, the ability to track how much cortisol is accumulating within nail clippings is complex and may represent a large timespan. Further, very few studies have reported effect sizes and investigated the effects of covariates, such as age, sex, ethnicity, and nail characteristics, which limits the validation of this measure. Further studies are required to validate the utility of nail cortisol as a biomarker of chronic stress across the human lifespan.

A culturally and gender responsive stress and chronic disease prevention intervention for low/no-income African American men: The MOCHA moving forward randomized control trial protocol

Low/no-income, African American men are disproportionally burdened by chronic disease resulting from a complex interplay of systemic, sociocultural, and individual factors. These disparities are related to poverty, racism, gender role strain, high levels of stress, low levels of physical activity, and malnutritious diet. Men of Color Health Awareness (MOCHA) is a community-driven movement to address the physical, mental, social, and spiritual needs of men of color. As part of ongoing programming, the MOCHA Standard intervention consists of a 10-week program including: (1) small group discussions of issues particularly relevant to men of color, (2) classes on health topics focusing on chronic disease control, such as nutrition, obesity, high blood pressure, fitness, and the social determinants of health; and (3) 60-min of moderately intensive aerobic exercise twice a week. While the MOCHA Standard intervention has yielded positive results, feedback from previous participants warranted an in-depth sociocultural tailoring of the curriculum to improve community receptiveness, in particular, revising the sessions to "narrativize" the materials to strengthen their potential effectiveness. This manuscript describes the novel recruitment strategies; the development of an enhanced MOCHA+ Stories Matter program that uses narrative communication strategies; and the methodology used to assess the comparative effectiveness of the MOCHA Standard relative to MOCHA+ Stories Matter program in lowering stress and risk of chronic diseases in a randomized controlled trial. The results of this research will contribute to the identification of effective interventions to address health disparities in low-income African-American men and the dissemination of effective chronic disease prevention programming.

Assessment of prenatal stress-related cortisol exposure: focus on cortisol accumulation in hair and nails

Prenatal stress adversely affects offspring development. Although cortisol is hypothesized to be a key mediator of stress-induced developmental deficits, determining the amount of fetal cortisol exposure produced by maternal stress has proved challenging. Current approaches, such as measuring cortisol concentrations in maternal plasma, saliva, or urine, amniotic fluid, fetal plasma, or cord blood, all have significant limitations for assessing cumulative fetal cortisol exposure over time. A recently emerging approach is to measure cortisol concentrations in maternal hair and/or newborn hair or nail samples. Maternal hair cortisol potentially shows long-term production across each trimester of pregnancy, whereas neonatal hair or nail cortisol is thought to reflect mainly third trimester hormone accumulation. This review first describes fetal adrenocortical development, placental cortisol metabolism, and the various sources of fetal cortisol exposure across pregnancy. We then summarize the results obtained from "classical" methods of assessing prenatal cortisol exposure prior to the advent of hair and nail cortisol measurement. Lastly, we discuss the initial development and validation of the hair cortisol methodology, its subsequent application to studies of chronic stress, and recent findings regarding maternal and neonatal hair or nail cortisol concentrations in relation to prenatal stress and other variables of interest.

Detection of C-peptide in human hair and nail: a comparison between healthy persons and persons with type 1 diabetes

OBJECTIVES

Serum and urinary C-peptide has clinical implications in people with/without diabetes. Recently, C-peptide was detected in hair samples of healthy adults but not studied in people with diabetes. It is not known whether C-peptide can be detectable in nail tissue or not. This study aims to assess the detection of C-peptide in hair and nail samples and to find whether hair and nail C-peptide levels are different in type 1 diabetes mellitus (T1DM) compared with healthy individuals.

RESEARCH DESIGN AND METHODS

In a prospective case-control study on 41 subjects with T1DM and 42 control subjects, hair and nail samples were collected and prepared. C-peptide was extracted by incubating the samples with methanol and measuring the extract with an immunoassay. The hair and nail C-peptide values were compared between the T1DM and control group and their correlations with each other and with other variables were assessed with a significant level set at 0.05.

RESULTS

Hair and nail C-peptide levels were detected in both groups, with significantly lower values in T1DM compared with the control group. T1DM with >7-year diabetes duration had significantly lower C-peptide in serum, nails and hair. Hair and nail C-peptide levels have significant positive correlations with each other and negative correlations with age.

CONCLUSIONS

We conclude that C-peptide are detectable in the hair and nails of healthy persons and persons with T1DM. Compared with the healthy persons, persons with T1DM had significantly lower hair and nail C-peptide and significant hair/nail C-peptide reduction after 7 years of diagnosis. Our results suggest that hair and nails are suitable matrices for the measurement of C-peptide in healthy persons and persons with T1DM.

Fingernail cortisol - State of research and future directions

The extraction of cortisol from fingernails represents a recent advancement in the retrospective, long-term assessment of hypothalamic-pituitaryadrenal (HPA) axis activity: Fingernail cortisol has the potential to overcome some of the major disadvantages of established HPA axis markers. However, the introduction of any novel methodology also raises certain caveats. This review provides a comprehensive summary of the current state of research on fingernail cortisol. It identifies a number of strengths of his novel methodology (e.g., its high feasibility), while also pointing out open questions which currently challenge the interpretability of fingernail findings, in particular regarding the time period of cortisol secretion reflected in fingernail samples, as well as regarding potential determinants or confounders of fingernail cortisol (e.g. sociodemographic, lifestyle, or health characteristics). Clarification of these issues in the context of further methodological studies is necessary to validate the use of fingernail cortisol as a retrospective marker of HPA axis activity.

Correlation of selected stress associated factors with vitamin D deficiency in Jordanian men and women

Background: To identify stress associated factors for vitamin D deficiency (VDD) in healthy Jordanian people based on serum 25(OH)D levels.

Design: Prospective cohort study.

Methods: Three hundred and seventy-one Jordanian men and women aged 17–52 years, who were identified as VD deficient 25(OH)D <30 ng/mL, were eligible to participate in the study. Serum vitamin 25(OH) D was measured using chemiluminescent immunoassay. Cortisol, parathyroid hormone, calcium, phosphate, fasting lipid profile, and blood glucose were also analyzed. Questionnaires were used to collect lifestyles parameters. Anthropometric parameters including: body mass index (BMI), waist (W) and hip (H) circumferences, W/H ratio (WHR) were also calculated.

Results: The vast majority (91%) of the participants had vitamin D deficiency (25- (OH) D <30 ng/mL). Positive correlations were observed between vitamin D deficiency and the following anthropometric parameters in all study sample; gender (P=0.010), height (P=0.22), height/hip ratio (P=0.015) and waist/hip ratio (P=0.013). Lifestyle parameters that indicated very weak positive correlations with VDD were number of family members (P=0.011) and insufficient exposure to sunlight (P=0.023). The following clinical parameters showed weak or very weak correlations with VDD; serum cortisol (r=0.318), low density lipoprotein (r=0.246) and total cholesterol (r=0.133). Skin color and water pipe tobacco smoking were added to the multivariable stepwise regression analyses as they have been weakly correlated with VDD. These predictors together explained only 12.2% of the variance in serum cortisol levels in the VDD study sample.

Conclusion: A weak positive association between VDD and elevated serum cortisol was observed in this study. Subcutaneous changes may be involved in that association but further studies are needed to clarify a potential role for adrenocorticotropic hormone (ACTH).

Stressful life events, insomnia and suicidality in a large sample of Chinese adolescents

AIMS

This study aimed to examine the associations between stressful life events, insomnia, and suicidality including suicidal ideation (SI), suicide plan (SP) and suicide attempt (SA) in a large sample of Chinese adolescents.

METHODS

A total of 11,831 adolescents who participated in the baseline survey of Shandong Adolescent Behavior and Health Cohort were included for the analysis. Participants were sampled from 8 middle/high schools in 3 counties of Shandong, China. Participants completed a structured behavior and health questionnaire, including suicidality, demographics, depression/anxiety, stressful life events (SLEs), and insomnia in November-December 2015. A series of logistic regression models and mediation analyses were performed to examine the associations between SLEs, insomnia and suicidality.

RESULTS

The prevalence rates of overall suicidality, SI, SP and SA in the last year were 13.1%, 12.5%, 3.3%, and 1.5%, respectively. SLEs were significantly associated with overall suicidality, SI, and SP. Insomnia was an independent risk factor of suicidality and a mediator of the association between SLEs and suicidality. The total effect of SLEs on overall suicidality was 0.597 (95%CI: 0.534-0.661), including 0.457 (95%CI: 0.391-0.523) for direct effect and 0.158 (95%CI: 0.138-0.178) for indirect effect. Insomnia also mediated the associations of SLEs with SI, SP and SA, respectively.

LIMITATIONS

Causal relationship could not be concluded because this study is cross-sectional.

CONCLUSIONS

Stressful life events and insomnia are directly associated with suicidality in adolescents. The association between SLEs and suicidality is partially mediated by insomnia.

Innovations in biological assessments of chronic stress through hair and nail cortisol: Conceptual, developmental, and methodological issues

Much of the existing research on biological mechanisms underlying the stress experience has focused largely on moment-to-moment stress, rather than on chronic stress, an arguably more powerful predictor of long-term outcomes. Recent methodological innovations have paved the way for new lines of research on chronic stress, with promising implications for developmental researchers and for those who study health and adversity. In particular, there are increasing studies that have focused on chronic stress assessments by relying on cortisol derived from hair and nails as a biomarker for chronic stress. In this paper, we provide an overview of their use, describe how hair and nail cortisol ought to be conceptualized differently across the lifespan, how developmental factors may impact its interpretation, and the circumstances under which its use may be more methodologically sensible. The purpose of this review is to provoke further discussion and encourage careful research designs that utilize hair and nail cortisol for understanding the effects of chronic stress exposure from the early developmental period, across adverse contexts, and in association with psychological and physical health outcomes.

Associations of perceived stress with the present and subsequent cortisol levels in fingernails among medical students: a prospective pilot study

Purpose

Cortisol in fingernails could retrospectively reflect cumulative stress over a long period. However, the association between fingernail cortisol and perceived stress needs to be validated. This exploratory study aimed to investigate the associations of perceived stress with the present and subsequent cortisol levels in fingernails of the subjective stress measurement among medical students.

Methods

Students were recruited from a medical university in Shenyang, China. The final sample consisted of 51 students (16 men, 35 women). On the Day 30 of our data and fingernail collection procedure, the 10-item Perceived Stress Scale was used to measure perceived stress. Fingernail samples were collected twice, on Days 15 (denoted as FD15) and 45 (denoted as FD45) of the procedure, and participants were asked to grow fingernails for 15 days in each collection. Cortisol was determined by an enzyme immunoassay method using the ELISA kit. Multiple linear regression was performed to examine the association between perceived stress and cortisol level. The Bonferroni correction was made for multiple comparisons.

Results

The level of cortisol was 5.65 pg/mg (SD =1.88) for FD15 and 5.41 pg/mg (SD =1.63) for FD45. Perceived stress was not associated with the cortisol level of FD15 (β=−0.014, P=0.924), but it was significantly and positively associated with the cortisol level of FD45 (β=0.436, P=0.003), which remained significant after Bonferroni correction. The associations between fingernail cortisol and demographic variables (gender, age, BMI, and physical activity) were not significant.

Conclusion

This study was the first to investigate fingernail cortisol in China. Perceived stress was positively associated with the subsequent cortisol levels in fingernails, but not the present. The findings suggested that fingernail cortisol could indicate stress exposure in the past. Furthermore, a simple and easy self-reported measure could reflect cumulative stress as measured by fingernail cortisol.