State associations with the cortisol awakening response in healthy females

Relationship of sleep with diurnal cortisol rhythm considering sleep measurement and cortisol sampling schemes

Information on the relationships between the previous night's sleep and the next-day diurnal cortisol rhythm is inconsistent due to confounding factors such as sleep measurements (trait/state sleep and objective/subjective sleep) and cortisol sampling schemes. Therefore, this study aimed to investigate these relationships, considering the confounding factors. College students (n = 79) wore actigraphy for 3 days to undergo an evaluation of previous night-time sleep objectively and reported their subjective sleep parameters in a sleep diary. In addition, participants provided six salivary cortisol samples daily. Furthermore, six cortisol sampling schemes were created to reflect diurnal cortisol rhythms, and two different methods were used to calculate the index of diurnal cortisol slope (DCS). A multilevel model was created to examine the impact of both trait and state sleep on next-day diurnal cortisol rhythm. The results revealed that higher objective state sleep efficiency and longer objective state total sleep time were associated with a higher cortisol awakening response (CAR). Moreover, higher objective trait sleep efficiency and longer objective trait total sleep time were associated with higher waking cortisol levels and steeper DCS. In addition, a minimum of four saliva samples were required at different time points, including upon waking, 30 min after waking, 1 h after waking, and at bedtime, to explore the relationship of sleep efficiency/total sleep time with waking cortisol, CAR, and DCS. Furthermore, the index of the peak-to-bed slope was appropriately employed to examine the relationship between sleep efficiency and DCS, whereas the wake-to-bed slope was effective for examining the relationship between total sleep time and DCS. In summary, this study clarified the relationship between sleep and next-day diurnal cortisol rhythm and suggested a cost-effective cortisol sampling schedule and calculation methods.

Physical Activity and Cortisol Regulation: A Meta-Analysis

Physical activity participation is associated with effective stress coping, indicated by decreases in both physiological stress reactivity and perceived stress. Quantifying the effect of physical activity on the diurnal regulation of one key physiological stress indicator, the stress hormone, cortisol, across studies may demonstrate the extent to which physical activity participation is associated with diurnal HPA axis regulation. We meta-analyzed studies examining relations between physical activity participation and indices of HPA axis regulation: the diurnal cortisol slope and the cortisol awakening response. We also examined moderators of the relation. The analysis revealed a small, non-zero negative averaged correlation between physical activity and the diurnal cortisol slope (r = -0.043, 95% CI [-0.080, -0.004]). Examination of sample sociodemographic differences, study design characteristics, cortisol measurement methods, and physical activity variables as moderators revealed few effects on the relation between physical activity and diurnal cortisol slope. We did not observe lower levels of variability in the mean cortisol awakening response at higher levels of physical activity participation, and moderator analyses showed little evidence of reductions in heterogeneity for this effect. We found some evidence of systematic publication bias. Findings suggest higher physical activity is associated with a steeper diurnal cortisol slope. However, the cortisol awakening response did not differ by physical activity level. Future studies testing the physical activity and cortisol regulation association should use standardized physical activity measures, follow guidelines for better quality cortisol sampling collection and analysis, and test relations in large-scale empirical studies to confirm the direction and causality of the effect.

Effects of late-night eating of easily-or slowly-digestible meals on sleep, hypothalamo-pituitary-adrenal axis, and autonomic nervous system in healthy young males

Aim of the current study was to assess the effects of the digestibility of late-night high calorie meal on sleep and the activities of the hypothalamo-pituitary-adrenal (HPA) and autonomous nervous system (ANS) in healthy young males. For that purpose, effects of an easily digestible meal (starch + sugar-rich meal, SSR, i.e., dessert) or a slowly digestible meal (protein + fat-rich, PFR, i.e. kebab) were investigated in a crossover design in 16 participants (20-26 year old). They did not eat anything after 07:00 PM on Day 0; had an SSR meal on Day 1 and a PFR meal on Day 2 at 10:00 PM. HPA and ANS activities were measured by cortisol awakening response (CAR) and heart rate variability (HRV), respectively. The participants provided salivary samples for CAR; had a 5-min continuous electrocardiogram recording for HRV; and filled in sleep questionnaires. Late-night eating of SSR and PFR diets increased the area under the curve of CAR (p < 0.05) but did not affect HRV parameters (p > 0.05). PFR meal significantly disturbed sleep (p < 0.05). The data suggests that increased activity of HPA, but not ANS, might be involved in pathophysiology of late-night eating and that this might be due to disturbed sleep if slowly-digestible meal is consumed.

Brain preparedness: The proactive role of the cortisol awakening response in hippocampal-prefrontal functional interactions

Upon awakening from nighttime sleep, the stress hormone cortisol in humans exhibits a robust rise within thirty to forty-five minutes. This cortisol awakening response (CAR), a crucial point of reference within the healthy cortisol circadian rhythm, has been linked to various psychological, psychiatric and health-related conditions. The CAR is thought to prepare the brain for anticipated challenges of the upcoming day to maintain one's homeostasis and promote adaptive responses. Using brain imaging with a prospective design and pharmacological manipulation, we investigate the neurobiological mechanisms underlying this preparation function of the CAR across two studies. In Study 1, a robust CAR is predictive of less hippocampal and prefrontal activity, though enhanced functional coupling between those regions during a demanding task hours later in the afternoon. Reduced prefrontal activity is in turn linked to better working memory performance, implicating that the CAR proactively promotes brain preparedness based on improved neurocognitive efficiency. In Study 2, pharmacologically suppressed CAR using Dexamethasone mirrors this proactive effect, which further causes a selective reduction of prefrontal top-down functional modulation over hippocampal activity. These findings establish a causal link between the CAR and its proactive role in optimizing functional brain networks involved in neuroendocrine control, executive function and memory.

Awakening cortisol indicators, advanced glycation end products, stress perception, depression and anxiety in parents of children with chronic conditions

This cross-sectional study aims to investigate awakening cortisol indicators and to explore their association with stress perception, advanced glycation end products (AGEs), depression and anxiety in parents of children with chronic conditions. We included five parental groups according to children's diagnoses: Down syndrome (DS; N = 31), autistic spectrum disorder (ASD; N = 29), cerebral palsy (CP; N = 15), diabetes mellitus type 1 (DMT1; N = 38), and a control group of heathy children (CG; N = 33). Salivary cortisol and AGEs were measured, alongside with psychological indices. Partial correlation and multiple linear regression were used in the analysis to identify parental characteristics associated with total awakening cortisol output (area under the curve with respect to the ground, AUC_G), cortisol awakening response (area under the curve with respect to the increase, AUC_I), perceived stress, and health outcomes (AGEs, depression and anxiety). There was no difference between groups for AUC_G, while DS and DMT1 groups showed reduced AUC_I (β = -0.241, p = 0.040; β = -0.249, p = 0.028, respectively), and ASD parents had a borderline insignificant result (β = -0.205, p = 0.081). Non-smokers had higher AUC_G, and parental sedentary activity and sleep duration were associated with AUC_I. AUC_G was positively associated with AGEs (β = 0.218, p = 0.013), anxiety (β = 0.207, p = 0.004), and with depression (β = 0.156, p = 0.034), unlike the AUC_I. DS parental group showed lower general stress perception (β = -0.260, p = 0.005). Parents of children with DMT1 had more pronounced depressive symptoms (β = 0.183, p = 0.039), while CP parents had a borderline insignificant result for depression (β = 0.143, p = 0.058). Based on these results, parents of children with chronic conditions have altered awaking cortisol response and are under increased risk of adverse health consequences.

Cortisol reactivity to a psychosocial stressor significantly increases the risk of developing Cognitive Impairment no Dementia five years later

Alzheimer's disease (AD) patients show high cortisol levels suggesting that biological mediators of stress may play a role in the neurodegenerative process of cognitive disorders. However, there is no consensus as to whether cortisol concentrations represent a risk factor for the development of cognitive impairment. We analyzed the potential association between the incidence of cognitive impairment and cortisol concentrations under basal and acute stress conditions in 129 individuals aged 50 years or older, with preserved cognitive and functional abilities. All participants were recruited in 2011 for assessment of cognitive performance and cortisol levels. Cortisol was analyzed in saliva samples collected during two typical and consecutive days, in the morning, afternoon, and night, and also during exposure to an acute psychosocial stressor (Trier Social Stress Test - TSST). After a five-year follow-up, 69 of these volunteers were reassessed for cognitive performance, functional evaluation, memory complaints, and depression. The incidence of cognitive impairment not dementia (CIND) was 26.1 %, and was positively associated with greater TSST-induced cortisol release (responsiveness) [(95 % CI = 1.001-1.011; B = 0.006), p = 0.023]. Moreover, five years before diagnosis, participants who later developed CIND had greater responsiveness to TSST (p = 0.019) and lower cortisol awakening response (CAR: p = 0.018), as compared to those who did not develop CIND. These findings suggest that higher psychosocial stress responsiveness profiles may represent a preclinical sign of cognitive impairment.

Stress, the cortisol awakening response and cognitive function

There is evidence that stress-induced disruption of the circadian rhythm of cortisol secretion, has negative consequences for brain health. The cortisol awakening response (CAR) is the most prominent and dynamic aspect of this rhythm. It has complex regulatory mechanisms making it distinct from the rest of the cortisol circadian rhythm, and is frequently investigated as a biomarker of stress and potential intermediary between stress and impaired brain function. Despite this, the precise function of the CAR within the healthy cortisol circadian rhythm remains poorly understood. Cortisol is a powerful hormone known to influence cognition in multiple and complex ways. Studies of the CAR and cognitive function have used varied methodological approaches which have produced similarly varied findings. The present review considers the accumulating evidence linking stress, attenuation of the CAR and reduced cognitive function, and seeks to contextualize the many findings to study populations, cognitive measures, and CAR methodologies employed. Associations between the CAR and both memory and executive functions are discussed in relation to its potential role as a neuroendocrine time of day signal that synchronizes peripheral clocks throughout the brain to enable optimum function, and recommendations for future research are provided.

Hair Cortisol Is Associated With Social Support and Symptoms in Schizophrenia

INTRODUCTION

Psychosocial stressors may worsen psychotic symptoms in schizophrenia, while social support could protect against the effects of stress in schizophrenia. Hypothalamus-pituitary-adrenal axis dysfunction has been associated with schizophrenia. Hair cortisol concentrations (HCC) allow assessment of cumulative cortisol secretion over the preceding 3 months. The relationship between HCC, psychosocial stressors, social support, and the clinical characteristics of schizophrenia needs to be explored.

METHODS

One hundred nine schizophrenia patients and 86 healthy controls between the ages of 18 and 60 were enrolled in the study. Three-centimeter samples of hair were collected from the scalp and HCC were measured using ELISA kits. Linear regression and factor analysis were employed to examine the relationship between HCC, childhood trauma, the number of stressful life events (SLE), the amount of social support in the 3 months prior to the hair cortisol assessment and clinical characteristics of schizophrenia.

RESULTS

Schizophrenia patients experience more SLE in their lifetime, receive less social support, and have lower HCC in the recent 3 months compared to healthy controls. In the schizophrenia patients, HCC are positively associated with the amount of social support and negatively associated with the severity of delusions. The interaction between social support and SLE predicts decreased HCC. Factor analysis shows that a subgroup of schizophrenia patients who experience childhood trauma and SLE are characterized by decreased HCC.

CONCLUSIONS

Findings indicate social support could be a moderator for the relationship between SLE and HCC which may attenuate the effects of SLE in schizophrenia.

Premenstrual syndrome is associated with altered cortisol awakening response

Previous studies have revealed stress-induced dysregulation of hypothalamic-pituitary-adrenal (HPA) axis in women with premenstrual syndrome (PMS). So far, however, the results about the relationship between HPA axis dysregulation and PMS are mixed. To this end, it is necessary to investigate the basal activity of the HPA axis in women with PMS instead of only assessing a certain stressor. Therefore, this study evaluated the relationship between the cortisol awakening response (CAR) and PMS. Thirty-two women with PMS (mean age 22.47 ± 2.20 years) and 36 healthy controls (mean age 22.28 ± 2.43 years) were included in this study. Saliva samples of our participants were collected successively at 0, 30, 45, and 60 min after awakening to assess CAR during each of two phases of the menstrual cycle (the mid-follicular phase and the late luteal phase). The results showed a significantly attenuated CAR in women with PMS compared with the healthy controls, especially at 45 and 60 min after awakening, regardless of the menstrual cycle phases. Furthermore, there was a significant negative correlation between PMS severity as measured by PMS scale and AUCi (i.e. the Area Under the Curve with respect to increase) in the mid-follicular phase. Our findings suggested that an attenuated CAR activity profile may be an important risk factor for the development of PMS.

Variability of the cortisol awakening response and morning salivary oxytocin in late adolescence

Exogenously administered oxytocin interacts with the hypothalamic-pituitary-adrenal (HPA) axis to modulate endogenous cortisol levels, suggesting a synergistic role for these two hormones in the response to stress, cognitive performance and the development of psycho-behavioural disorders. The cortisol awakening response (CAR) is considered a reliable measure of HPA axis function in humans. However, the CAR appears to vary considerably from day to day and may be strongly influenced by the anticipated demands of the day ahead. The level of variation intrinsic to the CAR is unclear because few studies have examined the CAR in the absence of daily environmental variation. It is not known whether oxytocin has a similar or complementary awakening response. Therefore, over three consecutive days, we examined 12 adolescents (aged 15-17 years) in a highly-controlled sleep laboratory. Saliva was collected on days 4-6 of a 9-day laboratory visit. Cortisol and oxytocin levels were determined by an enzyme-linked immunosorbent assay from saliva sampled at 0, 15, 30 and 45 minutes, and 8 and 12 hours post-awakening. CAR magnitude varied between days and was associated with sleep duration and pre-awakening sleep stage. Conversely, oxytocin levels dropped dramatically in the first 15 minutes post-awakening and were highly consistent across participants and days. Older participants had higher awakening oxytocin concentrations. Although cortisol increases and oxytocin rapidly declines upon awakening, their diurnal variation does not appear to be related at basal, peripheral levels, consistent with a previous finding that exogenously administered oxytocin only modulates cortisol under conditions of stress.

Hair cortisol and work stress: Importance of workload and stress model (JDCS or ERI)

Hair cortisol concentrations (HCCs) are a potential physiological indicator of work related stress. However, studies that tested the relationship between HCC and self-reported stress in a work setting show mixed findings. This may be because few studies used worker samples that experience prolonged stress. Therefore, we compared a high workload sample (n = 81) and a normal workload sample (n = 91) and studied whether HCC was related to: (i) high job demands, low control, and low social support (JDCS model), and (ii) high effort, low reward, and high overcommitment (ERI model). Results showed that self-reported stress related to HCC only in the high workload sample and only for the variables of the ERI model. We found that HCC was higher when effort was high, reward low, and overcommitment high. An implication of this study is that a certain stress threshold may need to be reached to detect a relationship between self-reported stress and physiological measures such as HCC.

Genotype Influences Day-to-Day Variability in Sleep in Drosophila melanogaster

Patterns of sleep often vary among individuals. But sleep and activity may also vary within an individual, fluctuating in pattern across time. One possibility is that these daily fluctuations in sleep are caused by the underlying genotype of the individual. However, differences attributable to genetic causes are difficult to distinguish from environmental factors in outbred populations such as humans. We therefore employed Drosophila as a model of intra-individual variability in sleep using previously collected sleep and activity data from the Drosophila Genetic Reference Panel, a collection of wild-derived inbred lines. Individual flies had significant daily fluctuations in their sleep patterns, and these fluctuations were heritable. Using the standard deviation of sleep parameters as a metric, we conducted a genome-wide association study. We found 663 polymorphisms in 104 genes associated with daily fluctuations in sleep. We confirmed the effects of 12 candidate genes on the standard deviation of sleep parameters. Our results suggest that daily fluctuations in sleep patterns are due in part to gene activity.

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

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

Assessment of the cortisol awakening response: Real-time analysis and curvilinear effects of sample timing inaccuracy

The cortisol awakening response (CAR) is typically measured in the domestic setting. Moderate sample timing inaccuracy has been shown to result in erroneous CAR estimates and such inaccuracy has been shown partially to explain inconsistency in the CAR literature. The need for more reliable measurement of the CAR has recently been highlighted in expert consensus guidelines where it was pointed out that less than 6% of published studies provided electronic-monitoring of saliva sampling time in the post-awakening period. Analyses of a merged data-set of published studies from our laboratory are presented. To qualify for selection, both time of awakening and collection of the first sample must have been verified by electronic-monitoring and sampling commenced within 15min of awakening. Participants (n=128) were young (median age of 20 years) and healthy. Cortisol values were determined in the 45min post-awakening period on 215 sampling days. On 127days, delay between verified awakening and collection of the first sample was less than 3min ('no delay' group); on 45days there was a delay of 4-6min ('short delay' group); on 43days the delay was 7-15min ('moderate delay' group). Cortisol values for verified sampling times accurately mapped on to the typical post-awakening cortisol growth curve, regardless of whether sampling deviated from desired protocol timings. This provides support for incorporating rather than excluding delayed data (up to 15min) in CAR analyses. For this population the fitted cortisol growth curve equation predicted a mean cortisol awakening level of 6nmols/l (±1 for 95% CI) and a mean CAR rise of 6nmols/l (±2 for 95% CI). We also modelled the relationship between real delay and CAR magnitude, when the CAR is calculated erroneously by incorrectly assuming adherence to protocol time. Findings supported a curvilinear hypothesis in relation to effects of sample delay on the CAR. Short delays of 4-6min between awakening and commencement of saliva sampling resulted in an overestimated CAR. Moderate delays of 7-15min were associated with an underestimated CAR. Findings emphasize the need to employ electronic-monitoring of sampling accuracy when measuring the CAR in the domestic setting.

Blunted Cortisol Awakening Response and Poor Self-Perceived Health in Informal Caregivers of People with Eating Disorders

Caring for offspring diagnosed with eating disorders (EDs) entails being under high chronic stress, with negative consequences for health. However, most previous research has only evaluated self-report measures of health, biological markers being poorly studied. In this regard, the evaluation of the cortisol awakening response (CAR) could add significant information about the biological basis of health disturbances in this population. The main aim of the present study was to compare CAR and self-reported health between informal caregivers (ICs) of people with EDs and non-caregivers. Furthermore, we explored the effect of the nature of the diagnosis, comparing ICs of people with anorexia and bulimia nervosa. ICs had a blunted CAR, and more anxiety and insomnia, and social dysfunction, together with poorer perceived general health than non-caregivers. ICs of people with anorexia nervosa had higher levels of morning cortisol and burden, and more social dysfunction and severe depression than those of people with bulimia nervosa. Our results demonstrate marked health problems in ICs of people with EDs, especially when the care recipient has anorexia nervosa. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association.

Assessing the daily stability of the cortisol awakening response in a controlled environment

Background

Levels of cortisol, the end product of the hypothalamic-pituitary-adrenal (HPA) axis, display a sharp increase immediately upon awakening, known as the cortisol awakening response (CAR). The daily stability of the CAR is potentially influenced by a range of methodological factors, including light exposure, participant adherence, sleep duration and nocturnal awakenings, making inferences about variations in the CAR difficult. The aim of the present study was to determine the daily stability of multiple measurement indices of the CAR in a highly-controlled sleep laboratory environment. A secondary aim was to examine the association between objective sleep continuity and sleep architecture, and the CAR.

Methods

The CAR was assessed in 15 healthy normal sleepers (seven male, eight female, M_age = 23.67 ± 3.49 years) on three consecutive weekday mornings. Sleep was measured objectively using polysomnography. Saliva samples were obtained at awakening, +15, +30, +45 and +60 min, from which multiple CAR measurement indices were derived: cortisol levels at each time point, awakening cortisol levels, the mean increase in cortisol levels (MnInc) and total cortisol secretion during the measurement period. Morning 2 and Morning 3 awakening cortisol levels, MnInc and total cortisol secretion were compared and the relationship between Night 1 and Night 2 objective measures of sleep continuity and architecture, and the subsequent CAR, was also assessed.

Results

There were no differences in cortisol levels at each time point, or total cortisol secretion during the CAR period, between Morning 2 and Morning 3. Awakening cortisol levels were lower, and the MnInc was higher, on Morning 3. Morning 2 and Morning 3 awakening levels (r = 0.77) and total cortisol secretion (r = 0.82), but not the magnitude of increase, were positively associated.

Conclusions

The stability of the CAR profile and total cortisol secretion, but not awakening cortisol levels or the magnitude of increase, was demonstrated across two consecutive mornings of measurement in a highly-controlled environment. Awakening cortisol levels, and the magnitude of increase, may be sensitive to differences in daily activities.

Electronic supplementary material

The online version of this article (doi:10.1186/s40359-016-0107-6) contains supplementary material, which is available to authorized users.

Assessment of the cortisol awakening response: Expert consensus guidelines

The cortisol awakening response (CAR), the marked increase in cortisol secretion over the first 30-45 min after morning awakening, has been related to a wide range of psychosocial, physical and mental health parameters, making it a key variable for psychoneuroendocrinological research. The CAR is typically assessed from self-collection of saliva samples within the domestic setting. While this confers ecological validity, it lacks direct researcher oversight which can be problematic as the validity of CAR measurement critically relies on participants closely following a timed sampling schedule, beginning with the moment of awakening. Researchers assessing the CAR thus need to take important steps to maximize and monitor saliva sampling accuracy as well as consider a range of other relevant methodological factors. To promote best practice of future research in this field, the International Society of Psychoneuroendocrinology initiated an expert panel charged with (i) summarizing relevant evidence and collective experience on methodological factors affecting CAR assessment and (ii) formulating clear consensus guidelines for future research. The present report summarizes the results of this undertaking. Consensus guidelines are presented on central aspects of CAR assessment, including objective control of sampling accuracy/adherence, participant instructions, covariate accounting, sampling protocols, quantification strategies as well as reporting and interpreting of CAR data. Meeting these methodological standards in future research will create more powerful research designs, thus yielding more reliable and reproducible results and helping to further advance understanding in this evolving field of research.

Post awakening salivary cortisol secretion and trait well-being: The importance of sample timing accuracy

Indices of post awakening cortisol secretion (PACS), include the rise in cortisol (cortisol awakening response: CAR) and overall cortisol concentrations (e.g., area under the curve with reference to ground: AUCg) in the first 30-45 min. Both are commonly investigated in relation to psychosocial variables. Although sampling within the domestic setting is ecologically valid, participant non-adherence to the required timing protocol results in erroneous measurement of PACS and this may explain discrepancies in the literature linking these measures to trait well-being (TWB). We have previously shown that delays of little over 5 min (between awakening and the start of sampling) to result in erroneous CAR estimates. In this study, we report for the first time on the negative impact of sample timing inaccuracy (verified by electronic-monitoring) on the efficacy to detect significant relationships between PACS and TWB when measured in the domestic setting. Healthy females (N=49, 20.5±2.8 years) selected for differences in TWB collected saliva samples (S1-4) on 4 days at 0, 15, 30, 45 min post awakening, to determine PACS. Adherence to the sampling protocol was objectively monitored using a combination of electronic estimates of awakening (actigraphy) and sampling times (track caps). Relationships between PACS and TWB were found to depend on sample timing accuracy. Lower TWB was associated with higher post awakening cortisol AUCg in proportion to the mean sample timing accuracy (p<.005). There was no association between TWB and the CAR even taking into account sample timing accuracy. These results highlight the importance of careful electronic monitoring of participant adherence for measurement of PACS in the domestic setting. Mean sample timing inaccuracy, mainly associated with delays of >5 min between awakening and collection of sample 1 (median=8 min delay), negatively impacts on the sensitivity of analysis to detect associations between PACS and TWB.

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

BACKGROUND

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

METHODS/DESIGN

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

DISCUSSION

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

The effects of an anticipated challenge on diurnal cortisol secretion

In healthy, non-challenged individuals, the secretion of cortisol typically follows a diurnal profile characterized by a peak in the period following waking (cortisol awakening response) and a gradual decline throughout the day. In addition, cortisol secretion is increased in response to acutely stressful stimuli, particularly stressors involving social evaluation. The current study is the first to assess the impact of an anticipated acute laboratory stressor upon the typical diurnal pattern of HPA activation and relationship to acute cortisol secretion. A sample of 23 healthy young adults provided salivary cortisol samples at four time points (immediately upon awakening, 30-min post-awakening, 1200 h and before bed) on 2 consecutive days. On the second day, participants attended the laboratory and undertook an anticipated acute socially evaluative stressor immediately following provision of their 1200 h saliva sample. Heart rate, blood pressure and mood were recorded immediately before and after the stressor and at 10 and 20 min post-stressor along with additional salivary cortisol samples. Typical patterns of cortisol secretion were observed on both days and exposure to the laboratory stressor was associated with the expected increases in cortisol, heart rate, blood pressure and negative mood. However, significant differences in diurnal cortisol secretion were observed between the two days with greater secretion, in particular, during the period following awakening, evident on the day of the anticipated laboratory stressor. Furthermore, secretion of cortisol during the period following awakening was positively related to secretion during the acute reactivity periods. This is the first study to integrate a laboratory stressor into a typical day and assess its impact on indices of diurnal cortisol secretion in an ambulatory setting. The current findings support the notion that the cortisol awakening response is associated with anticipation of the upcoming day and the subsequent demands required of the individual.

Exploring day-to-day dynamics of daily stressor appraisals, physical symptoms and the cortisol awakening response

Stress is associated with the secretion of cortisol throughout the day, but less is known about the dynamic effects of stress on the cortisol awakening response (CAR). More widely, knowledge of the causal factors and functions of the CAR are also not fully understood. This study explored: (1) the effects of daily stressors on the next day CAR and; (2) the effects of the CAR on same day physical and affective outcomes. Sixty-four participants completed a daily diary, reporting on the occurrence of daily stressors and stress appraisals, physical symptoms, and affect. Cortisol was measured at 0, 15, 30, and 45 min after awakening to provide measures of the CAR on 3 consecutive work days. Stress appraisal was found to negatively predict the CAR, such that where stressors were appraised as more stressful (where perceived demands exceeded resources), the CAR increased less the following morning. Furthermore, the CAR significantly predicted same-day physical symptoms such that a lower CAR was associated with more physical symptoms. This study provides evidence for a pathway through which daily stressors may influence physical wellbeing, and highlights the importance of appraisals for future stress-based cortisol research.

Trajectories of diurnal cortisol in mothers of children with autism and other developmental disabilities: relations to health and mental health

This study used a stress biomarker, diurnal cortisol, to identify how elevated stress in mothers of children and adults with autism and other disabilities relates to their health and mental health. Based on semi-parametric, group-based trajectory analysis of 91 mothers, two distinctive cortisol trajectories emerged: blunted (63 %) or steep (37 %). Mothers in the blunted (vs. steep) trajectory had higher stress levels, lower health ratings, and 89 % of mothers of children with autism, and 53 % with other disabilities, belonged to this trajectory. Atypical cortisol awakening responses and evening rises were differentially associated with anxiety, depression, health problems and employment status. Stress-reducing interventions are needed for parents of children with autism and other disabilities that include biomarkers as indices of risk or treatment outcome.

The associations between adolescent sleep, diurnal cortisol patterns and cortisol reactivity to dexamethasone suppression test

Information on the associations between objectively measured sleep and hypothalamic-pituitary-adrenal axis function in early adolescence is scarce. We examined associations between average sleep duration and quality (sleep efficiency and wake after sleep onset) over 8 days with actigraphs and (1) diurnal cortisol patterns and (2) cortisol reactivity to a low-dose (3 μg/kg) overnight dexamethasone suppression test (DST) in a birth cohort born in 1998 (N=265 participants, mean age 12.3 years, SD=0.5). We also explored (3) if sleep duration and quality were affected the nights after the DST exposure. Cortisol was measured during 2 days, and participants were exposed to dexamethasone in the evening of first day. In boys, short sleep duration was associated with higher cortisol upon awakening and lower cortisol awakening response (CAR; P<0.05 and P<0.01). Long sleep duration in boys associated with higher CAR (P<0.02). Lower sleep quality in boys associated with lower CAR, but fell slightly short of significance (P<0.06). In girls, no significant associations were detected. Sleep quantity and quality were not associated with responses to the DST. There were no effects of DST on sleep (P>0.15 in between-subject analyses). The average sleep patterns showed associations with diurnal cortisol patterns during early adolescence, but only in boys. Sleep was not associated with cortisol reactivity to DST and the exogenous corticosteroid exposure did not affect sleep significantly.

The cortisol awakening response in toddlers and young children

The cortisol awakening response (CAR) is frequently assessed in psychoneuroendocrinological research on adult participants. However, knowledge on the development of the CAR during early life is scarce and characterized by inconsistent findings. We have recently shown that a positive CAR is readily observable in young infants under conditions of strict methodological control. However, it still remains unknown whether a significant CAR is maintained consistently throughout toddler- and childhood. Here, we report data from 150 toddlers and young children aged 12-87 months in whom salivary cortisol levels were assessed 0 and 30 min post-awakening over three non-consecutive study days. High quality of data was ensured by the use of objective measures to verify children's awakening times (wrist actigraphy) and sampling times (electronic monitoring containers). Results revealed the presence of a significant CAR (>1.5 nmol/L) in 142 (out of 150) children and on a total of 82% of study days. A marked CAR was consistently observed throughout all examined age groups (mean increase: 8.73 nmol/L). In addition, the level of cortisol on awakening was found to increase linearly with children's age (r=.17, p=.04). Overall, the current findings strongly suggest that, contrary to previous propositions, the CAR is maintained consistently throughout toddler- and childhood.

State variation in the cortisol awakening response

The cortisol awakening response (CAR) is a much studied but poorly understood aspect of the circadian pattern of cortisol secretion. A Scopus search of "cortisol" and "awakening" reveals 666 publications in this area since 1997 when it was first identified by Pruessner and colleagues as a "reliable biomarker of adrenocortical activity". The primary focus of the majority of these studies is centered on its utility as a biomarker associated with a range of psychosocial, physical and mental health variables. Such studies typically examine differences in the CAR (studied on 1 or 2 days) between healthy participants and other comparator groups of interest. Fewer studies (25 in our estimation) have examined correlates of day-to-day variation in the CAR in healthy participants, informing its role and regulation within the healthy circadian pattern of cortisol secretion. This is the first review to examine these studies which, although limited in number, offer a relatively coherent emerging story about state factors that influence the CAR and the impact of the CAR on daily functioning. Greater understanding of these issues helps illuminate the utility of the CAR as a promising biomarker in psychophysiological and epidemiological research. The review also highlights areas that require greater clarification and points to potentially fruitful areas of further research.

The cortisol awakening response in infants: ontogeny and associations with development-related variables

The cortisol awakening response (CAR) is a frequently used measure in psychoneuroendocrinological research, however, some of its more fundamental aspects still require attention. An important question in this respect concerns the ontogeny of the CAR. Data from two recent reports suggest that the CAR may only emerge relatively late during child development (≥16 months of age). However, as both enquiries did not use objective means of verifying participant adherence or infants' awakening times, it is unclear whether methodological factors may have contributed to these results. Here, we report data from a study on 33 infants aged 2-12 months with close care being taken to ensure the accuracy of sampling times by using wrist actigraphy and electronic monitoring containers. Salivary cortisol levels were assessed at 0 and 30 min post-awakening over three study days. Results revealed evidence for a significant CAR (≥2.5 nmol/L) in 32 (out of 33) infants and on a total 86.9% of study days, with a marked magnitude of the CAR across infants (mean estimated increase=12.54 nmol/L). In addition, the cortisol level on awakening and the CAR were found to be associated with different aspects of infant's physical and sleep-related development as well as with their weight and body mass index (BMI) at birth. Contrary to previous reports, the current results thus indicate that the ontogeny of the CAR occurs at an early stage of development and that it is present from as early as two months of life. The data also suggest that post-awakening cortisol secretion may undergo considerable changes during the first year of life associated with different aspects of infant development.

Do state factors moderate the relationship between depressive symptoms and morning cortisol?

To fully capitalize on the utility of morning cortisol in biosocial studies of health and well-being researchers must carefully control for potential confounds. Recent reports have highlighted wake time, workday, and anticipatory negative emotions as regulators of intra-individual variation, with the potential to obscure cortisol-trait associations if not properly controlled. The purpose of this analysis is to examine the potential for trait-factors (i.e., depressive symptoms) to interact with state fluctuations in the prediction of morning cortisol. Saliva samples were collected from 56 working women at awakening and 30 min post awakening. Samples were collected on four consecutive days-two non-workdays followed by two workdays. Confirming prior research, morning cortisol levels were higher on work days and when individuals had early wake times. However, this relationship was strongest for women with fewer depressive symptoms. Similarly, only in women with fewer depressive symptoms was workday related to higher cortisol levels, and the anticipation of high negative affect related to steeper CARs and higher cortisol levels. Findings raise the possibility that certain populations may not be as physiologically sensitive to external regulatory cues, thus affecting intra-individual differences in HPA axis activity. Implications for future biobehavioral studies of depression and studies involving non-clinical samples are discussed.

Blunted cortisol awakening response in men with first episode psychosis: relationship to parental bonding

Early life adversity has been associated with an increased risk for the development of mental health problems, including psychotic disorders, perhaps mediated by a changed regulation of the Hypothalamic Pituitary Adrenal (HPA) axis. Aim of the present study was to confirm our previous finding of an attenuated cortisol awakening response (CAR) in men with first episode psychosis (FEP) and to explore a possible link between a blunted CAR and early adversity as indicated by perceived parental bonding. Fifty-eight patients (38 men, 20 women; mean age 23.25±3.86) with a FEP and 33 healthy community controls (16 men, 17 women; mean age 22.91±3.64) participated in the study. Saliva samples for assessment of the CAR were collected immediately, 30 and 60min after awakening. Complete cortisol samples were available in a reduced sample of 56 patients (37 men) and 30 controls (13 men). Parental bonding during the first 16 years of life was assessed retrospectively with the Parental Bonding Inventory. Results showed a significantly blunted CAR in male compared to female patients, confirming our previously reported findings. We also found a lower CAR in the total FEP group compared to controls, which failed to reach significance after controlling for time of awakening. A significantly lower percentage of patients than controls reported optimal maternal parenting. Within the patient group, significantly fewer male than female patients reported optimal maternal and paternal parenting. Only in patients, unfavorable paternal parenting was related to a blunted CAR. Dysregulation of the HPA axis in male patients might be a consequence of non-optimal parenting and contribute to the less favorable course of psychosis in men compared to women.

Disordered eating behaviour is associated with blunted cortisol and cardiovascular reactions to acute psychological stress

Research suggests a potential dysregulation of the stress response in individuals with bulimia nervosa. This study measured both cardiovascular and cortisol reactions to a standardised laboratory stress task in individuals identified as showing disordered eating behaviour to determine whether dysregulation of the stress response is characteristic of the two branches of the stress response system. Female students (N=455) were screened using two validated eating disorder questionnaires. Twelve women with disordered eating, including self-induced vomiting, and 12 healthy controls were selected for laboratory stress testing. Salivary cortisol and cardiovascular activity, via Doppler imaging and semi-automatic blood pressure monitoring, were measured at resting baseline and during and after exposure to a 10-min mental arithmetic stress task. Compared to controls the disordered eating group showed blunted cortisol, cardiac output, heart rate, and stroke volume reactions to the acute stress, as well as an attenuated vasodilatory reaction. These effects could not be accounted for in terms of group differences in stress task performance, subjective task impact/engagement, age, BMI, neuroticism, cardio-respiratory fitness, or co-morbid exercise dependence. Our findings suggest that disordered eating is characterised by a dysregulation of the autonomic stress-response system. As such, they add further weight to the general contention that blunted stress reactivity is characteristic of a number of maladaptive behaviours and states.

Intraindividual stability of hair cortisol concentrations

The analysis of cortisol in human hair constitutes a promising method for the retrospective assessment of cumulative cortisol secretion over extended periods of time. An implicit assumption underlying the use of this method is that in the absence of major life changes hair cortisol concentrations show a high level of intraindividual stability, i.e. single hair cortisol assessments exhibit considerable trait-specificity and are only to a smaller extent influenced by state-dependent factors. Here, we present data from two independent studies examining patterns of intraindividual stability in hair cortisol levels. In study I, 45 participants were examined at two sampling points carried out one year apart from each other. In study II, 64 individuals provided data at three sampling points which occurred at two-month intervals. In both studies, at each time point hair was sampled and relevant psychosocial and hair-related variables were assessed. Results of both studies consistently revealed strong test-retest associations for repeated hair cortisol measurements ('r's between 0.68 and 0.79, 'p's <0.0001). Findings of structural equation modelling applied to data of study II showed that single hair cortisol assessments comprise a strong trait component, explaining between 59 and 82% of variance, and are only to a lesser extent influenced by state-related factors. Only inconsistent evidence for covariation of changes in hair cortisol concentrations and simultaneous changes in perceived stress or other relevant variables was seen across the two studies. The current findings suggest a considerable degree of intraindividual stability in hair cortisol levels which highlights the utility of this method for obtaining trait estimates of long-term cortisol secretion in psychoneuroendocrinological research.

Plasma cortisol concentrations and lifestyle in a population of outdoor workers

The aim of this study was to assess whether exposure to urban pollution in outdoor workers, may alter plasma cortisol concentrations also in relation to the effect of smoking and drinking habits. The research was carried out on 498 outdoor police workers, divided into three groups; Group A: traffic policemen (TP), Group B: drivers (D), Group C: Other duties (OD). To evaluate separately the effect of using alcohol and smoking, each group was divided into three subgroups: (1) non-smokers and non-drinkers, (2) smokers and non-drinkers, (3) non-smokers and drinkers. Our results show cortisol mean values were significantly higher in the TP group compared to the D and OD groups without significant differences between the last two groups. The results suggest that exposure to pollutants associated with urban psychosocial stress may play a more important role on plasma cortisol levels than smoking and alcohol.