The cortisol awakening response is related to executive function in older age

The Cortisol Awakening Response: Regulation and Functional Significance

In healthy individuals, the majority of cortisol secretion occurs within several hours surrounding morning awakening. A highly studied component of this secretory period is the cortisol awakening response (CAR), the rapid increase in cortisol levels across the first 30 to 45 minutes after morning awakening. This strong cortisol burst at the start of the active phase has been proposed to be functional in preparing the organism for the challenges of the upcoming day. Here, we review evidence on key regulatory and functional processes of the CAR and develop an integrative model of its functional role. Specifically, we propose that, in healthy individuals, the CAR is closely regulated by an intricate dual-control system, which draws upon key circadian, environmental, and neurocognitive processes to best predict the daily need for cortisol-related action. Fine-tuned CAR expression, in turn, is then assumed to induce potent glucocorticoid action via rapid nongenomic and slower genomic pathways (eg, affecting circadian clock gene expression) to support and modulate daily activity through relevant metabolic, immunological, and neurocognitive systems. We propose that this concerted action is adaptive in mediating two main functions: a primary process to mobilize resources to meet activity-related demands and a secondary process to help the organism counterregulate adverse prior-day emotional experiences.

Feelings of tense and risk of incident dementia: A prospective study of 482,360 individuals

BACKGROUND

The relationship between feelings of tense, as a significant emotional distress, and dementia remains unclear. This study aimed to evaluate the association between feelings of tense and dementia.

METHODS

In UK Biobank, feelings of tense were measured with a standard item. The primary outcome was all cause of dementia (ACD) and its subtypes (Alzheimer's disease (AD), vascular dementia (VD), and other dementia). Cox regression models analyzed the association between feelings of tense and dementia risk, while linear regression examined the correlation with neuroimaging outcomes. The potential association and joint effects of AD and tenseness were evaluated based on the established genetic risk score (GRS).

RESULTS

During a median follow-up of 12.7 years among 482,360 participants, 7331 dementia cases were identified. Individuals with feelings of tense had a significantly increased risk of ACD (HR, 1.194; 95 % CI: 1.115-1.278), VD (HR, 1.164; 95 % CI: 1.007-1.346), and other dementia (HR, 1.181; 95 % CI: 1.081-1.289), but not AD in multi-adjusted models. This association persisted across various sensitivity analyses and exhibited some heterogeneity in subgroup analyses. Furthermore, feelings of tense are associated with total brain volume shrinkage, higher white matter hyperintensities, and decreased partial subcortical volume, particularly in the hippocampus. No interaction between tenseness and AD genetic susceptibility was observed (P for interaction =0.346).

LIMITATIONS

Our study only considered feelings of tense measured at a one-time point.

CONCLUSIONS

Our findings demonstrate a significant association between feeling of tense and elevated dementia risk, indicating that tenseness could serve as a modifiable psychological determinant for dementia.

Sleep and dreaming in the light of reactive and predictive homeostasis

Dreams are often viewed as fascinating but irrelevant mental epihenomena of the sleeping mind with questionable functional relevance. Despite long hours of oneiric activity, and high individual differences in dream recall, dreams are lost into oblivion. Here, we conceptualize dreaming and dream amnesia as inherent aspects of the reactive and predictive homeostatic functions of sleep. Mental activity during sleep conforms to the interplay of restorative processes and future anticipation, and particularly during the second half of the night, it unfolds as a special form of non-constrained, self-referent, and future-oriented cognitive process. Awakening facilitates constrained, goal-directed prospection that competes for shared neural resources with dream production and dream recall, and contributes to dream amnesia. We present the neurophysiological aspects of reactive and predictive homeostasis during sleep, highlighting the putative role of cortisol in predictive homeostasis and forgetting dreams. The theoretical and methodological aspects of our proposal are discussed in relation to the study of dreaming, dream recall, and sleep-related cognitive processes.

Modifiable risk factors of dementia linked to excitation-inhibition imbalance

Recent evidence identifies 12 potentially modifiable risk factors for dementia to which 40% of dementia cases are attributed. While the recognition of these risk factors has paved the way for the development of new prevention measures, the link between these risk factors and the underlying pathophysiology of dementia is yet not well understood. A growing number of recent clinical and preclinical studies support a role of Excitation-Inhibition (E-I) imbalance in the pathophysiology of dementia. In this review, we aim to propose a conceptual model on the links between the modifiable risk factors and the E-I imbalance in dementia. This model, which aims to address the current gap in the literature, is based on 12 mediating common mechanisms: the hypothalamic-pituitary-adrenal (HPA) axis dysfunction, neuroinflammation, oxidative stress, mitochondrial dysfunction, cerebral hypo-perfusion, blood-brain barrier (BBB) dysfunction, beta-amyloid deposition, elevated homocysteine level, impaired neurogenesis, tau tangles, GABAergic dysfunction, and glutamatergic dysfunction. We believe this model serves as a framework for future studies in this field and facilitates future research on dementia prevention, discovery of new biomarkers, and developing new interventions.

The effect of pilates training on hormonal and psychophysical function in older women

BACKGROUND

DHEA-S and cortisol and their ratio are important determinants of some physiological and psychological function during aging. The present study aimed to determine the effect of eight weeks of pilates training on diurnal salivary cortisol, dehydroepiandrosterone sulfate (DHEA-S), and cortisol to DHEA-S ratio, cardiorespiratory fitness (CF), and psychological function in older women.

METHODS

Twenty-seven healthy older women (aged 60-65 years) participated in the study voluntarily and were divided into two groups of pilates training (N.=15) and control (N.=12), randomly. Before and after the experiment, salivary samples (at wake up and 30-min postawakening, midday, 5 p.m., and 9 p.m.) were taken and the participants completed the questionnaires. Cognitive function was assessed by the MMSE questionnaire. Pilates training was performed three times weekly, in non-consecutive days.

RESULTS

Pilates training increased V̇O2max (48%, P<0.001) and cognitive function (73%, P<0.001) and decreased BMI (16%, P=0.042), anxiety (53%, P<0.001) and depression (67%, P<0.001) compared to the control group. Also, in pilates training group, mean cortisol (16%, P=0.039), CAR (24%, P=0.010), fall after peak of cortisol (15%, P=0.50), morning DHEA-S (43%, P<0.001) and mean DHEA-S (34%, P=0.002) increased compared to the control group.

CONCLUSIONS

This study suggests that pilates training could improve mental and physical function which was accompanied by changes of diurnal cortisol and DHEA as one of the possible effective factors.

The cortisol awakening response and the late positive potentials evoked by unpleasant emotional pictures in healthy adults

The cortisol awakening response (CAR) refers to a sharp rise in cortisol concentrations within the 45 min following morning awakening. Alterations in CAR have been associated with various internalizing symptoms and brain function. The current study aimed to investigate the association between CAR and neural activity in response to unpleasant emotional pictures. A total of 46 healthy adults (22.55 years ± 1.69) collected saliva samples at 0, 30, and 45 min post-awakening on two days to assess the CAR. In the afternoon after CAR measurement on the first day, electroencephalograms were recorded when the participants completed a passive viewing task. The results showed that a greater CAR was associated with a decreased late positive potential difference score between unpleasant and neutral stimuli. This finding indicates that a larger CAR may be associated with decreased attentional engagement to unpleasant emotional information in healthy adults.

Resilience and vulnerability factors influence the cortisol awakening response in individuals vulnerable to suicide

Suicide is a global health issue. Dysregulated hypothalamic-pituitary-adrenal (HPA) axis activity, as measured by cortisol levels, has been identified as one potential risk factor. Evidence is emerging to suggest that different psychological factors may be associated with increased resilience and vulnerability in this context. The current study investigated whether trait resilience, social support, socially prescribed perfectionism, trait worry and trait impulsivity influenced the cortisol awakening response (CAR) over a 7-day study in individuals vulnerable to suicide. 142 participants with a history of suicidal attempt or ideation (suicide vulnerability group; n = 95) and with no suicide risk history (control group; n = 47) were recruited. Participants completed baseline questionnaires before commencing a 7-day study where they provided cortisol samples immediately upon waking, at 15 min, 30 min and 45 min on 7 consecutive days. Higher worry, socially prescribed perfectionism and impulsivity, lower resilience and social support were found in the suicide vulnerability group compared to the control group. Lower levels of resilience, higher levels of socially prescribed perfectionism, worry and impulsivity were associated with significantly lower total CAR. Suicide group membership was also found to have an indirect effect on total CAR via trait worry. The current findings show for the first time, that these well-known psychological risk factors for suicide are associated with smaller total cortisol awakening responses. Researchers ought to elucidate the precise causal mechanisms linking these traits, CAR and suicide risk in order to develop interventions to help build resilience in vulnerable populations.

Role of Cortisol and Testosterone in Risky Decision-Making: Deciphering Male Decision-Making in the Iowa Gambling Task

Despite the widely observed high risk-taking behaviors in males, studies using the Iowa gambling task (IGT) have suggested that males choose safe long-term rewards over risky short-term rewards. The role of sex and stress hormones in male decision-making is examined in the initial uncertainty and the latter risk phase of the IGT. The task was tested at peak hormone activity, with breath counting to facilitate cortisol regulation and its cognitive benefits. Results from IGT decision-making before and after counting with saliva samples from two all-male groups (breath vs. number counting) indicated that cortisol declined independent of counting. IGT decision-making showed phase-specific malleability: alteration in the uncertainty phase and stability in the risk phase. Working memory showed alteration, whereas inhibition task performance remained stable, potentially aligning with the phase-specific demands of working memory and inhibition. The results of hierarchical regression for the uncertainty and risk trials indicated that testosterone improved the model fit, cortisol was detrimental for decision-making in uncertainty, and decision-making in the risk trials was benefitted by testosterone. Cortisol regulation accentuated hormones' phase-specific effects on decision-making. Aligned with the dual-hormone hypothesis, sex, and stress hormones might jointly regulate male long-term decision-making in the IGT.

Diurnal cortisol secretion and health-related quality of life in healthy older people

Several studies have demonstrated that a dysregulated hypothalamic-pituitary-adrenal (HPA) axis is related to worse health status (e.g., depression, posttraumatic stress, or diabetes, among others). However, less is known about the association between the individual's perception of their own health status and HPA-axis functioning in healthy older people. The aim of the present study was to examine the relationship between HPA-axis functioning and health-related quality of life (HRQoL) in healthy older people. To do this, 140 healthy older people (69 men and 71 women) from 56 to 76 years old collected eight saliva samples on two consecutive weekdays to measure the diurnal cortisol cycle (i.e. awakening cortisol levels, cortisol awakening response (CAR), overall morning cortisol levels, change in the cortisol levels during the day, and bedtime cortisol levels). In addition, they completed the SF-36 questionnaire to obtain a measure of HRQoL (i.e. reflecting physical and mental functional health status). Results showed that higher awakening and bedtime cortisol levels and the CAR were associated with a better perception of both physical and mental health. In addition, the wake-to-bed cortisol slope was only positively related to physical health. No sex differences were found. These findings suggest that the awakening and bedtime cortisol levels and the CAR are the most relevant indices of diurnal cortisol secretion for understanding the relationship between HPA-axis functioning and HRQoL status in older people.

Circadian fluctuations in glucocorticoid level predict perceptual discrimination sensitivity

Slow neurobiological rhythms, such as the circadian secretion of glucocorticoid (GC) hormones, modulate a variety of body functions. Whether and how endocrine fluctuations also exert an influence on perceptual abilities is largely uncharted. Here, we show that phasic increases in GC availability prove beneficial to auditory discrimination. In an age-varying sample of N = 68 healthy human participants, we characterize the covariation of saliva cortisol with perceptual sensitivity in an auditory pitch discrimination task at five time points across the sleep-wake cycle. First, momentary saliva cortisol levels were captured well by the time relative to wake-up and overall sleep duration. Second, within individuals, higher cortisol levels just prior to behavioral testing predicted better pitch discrimination ability, expressed as a steepened psychometric curve. This effect of GCs held under a set of statistical controls. Our results pave the way for more in-depth studies on neuroendocrinological determinants of sensory encoding and perception.

An inverted U-shaped relationship between cortisol awakening response and same-day error monitoring function in healthy males

The cortisol awakening response (CAR) is thought to provide an energetic "boost" for the coming day and has been shown to be associated with prefrontal dependent function. The aim of the current study was to examine the relationship between the CAR and same-day neural activity following an error response task. Forty-six healthy males (22.25 years ± 1.98) collected saliva samples at 0, 30 and 45 min post-awakening to measure the CAR, and on the same afternoon event-related potential activity during error processing was measured. Although no association was observed between CAR and post-error behavior, a significant quadratic relationship was observed between CAR and Error-related Negativity (ERN) amplitude, and this association remained while controlling for confounding factors. This finding suggested the existence of an inverted U-shaped relationship between CAR and the same-day error-monitoring function in healthy males.

Therapeutic implications of hypothalamic-pituitaryadrenal-axis modulation in Alzheimer's disease: A narrative review of pharmacological and lifestyle interventions

With disease-modifying treatments for Alzheimer's disease (AD) still elusive, the search for alternative intervention strategies has intensified. Growing evidence suggests that dysfunction in hypothalamic-pituitaryadrenal-axis (HPAA) activity may contribute to the development of AD pathology. The HPAA, may therefore offer a novel target for therapeutic action. This review summarises and critically evaluates animal and human studies investigating the effects of pharmacological and non-pharmacological intervention on HPAA modulation alongside cognitive performance. The interventions discussed include glucocorticoid receptor antagonists and 11β-hydroxysteroid dehydrogenase inhibitors as well as lifestyle treatments such as physical activity, diet, sleep and contemplative practices. Pharmacological HPAA modulators improve pathology and cognitive deficit in animal AD models, but human pharmacological trials are yet to provide definitive support for such benefits. Lifestyle interventions may offer promising strategies for HPAA modification and cognitive health, but several methodological caveats across these studies were identified. Directions for future research in AD studies are proposed.

Biomarking Trait Resilience With Salivary Cortisol in Chinese Undergraduates

This study aimed to examine the relationship between trait resilience and salivary cortisol in a group of Chinese undergraduates. The Chinese versions of the Brief Resilience Scale and a measure of optimism, the revised Life Orientation Test were administered to 49 Chinese undergraduates who provided self-collected saliva samples six times per day (immediately after waking; 0.5, 3, 6, and 12 h thereafter; and at bedtime) over 3 consecutive weekdays. The cortisol data were aggregated across the 3 days to examine the association between resilience and components of the diurnal rhythm of cortisol using multiple regression. The results showed that higher resilience was associated with a stronger cortisol response to awakening and a steeper diurnal decline in cortisol from waking to bedtime. Resilience was positively associated with cortisol output over the course of the day but this relationship was not significant (p = 0.065). This pattern of diurnal rhythm is consistent with that typically observed in better adjusted individuals. Generated by an intensive protocol with compliance objectively monitored, these findings clearly indicate the important role of the hypothalamic-pituitary-adrenocortical axis in health and adjustment and contribute to the growing literature on resilience and cortisol in humans.

The Association Between Hair Cortisol, Hair Cortisone, and Cognitive Function in a Population-Based Cohort of Older Adults: Results From The Irish Longitudinal Study on Ageing

Experimental evidence to date largely supports an association between the stress hormone cortisol and cognitive performance. Older adults, in particular, may be vulnerable to the neurotoxic effects of prolonged increases in cortisol; however, the assessment of chronic hormone levels has previously been challenging. Hair cortisol analysis has advantages over other cortisol metrics for this purpose as it facilitates the assessment of total hormone secretion over several months. Cortisol and cortisone were measured in the scalp hair of 1,876 older adults from The Irish Longitudinal Study on Ageing. Participants underwent a battery of cognitive tests assessing global function, memory, executive function, and processing speed. After adjustment for hair characteristics, demographics, metabolic risk factors, cardiovascular conditions, and depression, regression analysis revealed an inverse relationship of hair glucocorticoids to immediate (cortisol: β = -.12, p = .032; cortisone: β = -.021, p = .036) and delayed (cortisol: β = -.13, p = .003; cortisone: β = -.23, p = .006) word recall performance. They were also associated with more errors on the Mini-Mental State Examination (cortisol: incidence rate ratio (IRR) = 1.06, p = .008; cortisone: IRR = 1.14, p = .002) and Montreal Cognitive Assessment (cortisone: IRR = 1.06, p = .015). Higher hair glucocorticoids are inversely associated with memory and global cognition in a population-based sample of older adults. Future work should explore the prognostic significance of these findings.

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.

Association of the HPA axis response to upcoming competition and shooting outcomes in elite junior shooting players

Successful shooting performance in competition is reliant on several factors such as shooting techniques and competition-associated psychological stresses. This study examined the hypothalamus-pituitary-adrenal (HPA) axis response to upcoming competition and its association with shooting outcomes in elite junior shooting players. The cortisol awakening response (CAR) and dehydroepiandrosterone (DHEA) secretion after awakening were measured for two consecutive days (the day before and on the day of competition for the selection of national shooting team members) in 19 junior men and 21 junior women players, and the shooting scores of the individual players were obtained. The total cortisol secretion during the CAR period (CARauc) increased, but total DHEA secretion during the post-awakening period (Dauc_awk) decreased on the day of competition, compared with one day before competition. The CARauc was higher in women than in men players, whereas Dauc_awk was higher in men than in women players across the two consecutive days. Cortisol and DHEA levels were comparable between low-scored (below the mean scores for air pistol or air rifle players) and high-scored players one day before competition. However, the CARauc on the day of competition was higher and the variations in the CARauc and molar CARauc/Dauc_awk ratios across the two consecutive days were greater in low-scored than in high-scored men and women players. These results indicated that upcoming competition involves alterations of the CAR and DHEA secretion after the awakening period, and greater HPA response to the upcoming competition was adversely associated with shooting scores in junior shooting athletes.Lay summaryAn important upcoming competition was perceived as a strong stressor on awakening that induced alteration in CAR and DHEA secretion after the awakening period in elite shooting players. This study observed that, irrespective of their age and period of shooting practice, the HPA axis function on the day of competition was associated with shooting outcomes in elite shooting players.

Poor inhibition of personally-relevant facial expressions of sadness and anger predicts an elevated cortisol response following awakening six months later

Failure to inhibit interference from distracting emotional stimuli may obstruct an individual's ability to regulate their behavioural and emotional responses to environmental stressors. Few studies have examined the longitudinal association between cognitive inhibition and regulation of the hypothalamic-pituitary-adrenal axis (HPA) in the natural environment. Seventy-nine healthy adults underwent two assessments 6 months apart. Participants' ability to suppress interference from distracting emotional stimuli was assessed using a negative affective priming task that included both generic and personally-relevant (i.e., participants' intimate partners) facial expressions of emotion. Poorer inhibition of personally-relevant sad and angry faces, but not generic stimuli, significantly predicted an increased cortisol awakening response (CAR) six months later. Moreover, poor inhibition of personally-relevant sad faces mediated the relation between chronic stress and an elevated CAR. Difficulties inhibiting personally-relevant emotional information may represent a key mechanism in understanding how environmental stress influences HPA functioning.

The effects of stress on cardiovascular disease and Alzheimer's disease: Physical exercise as a counteract measure

AD is a complicated multi-systemic neurological disorder that involves different biological pathways. Several risk factors have been identified, including chronic stress. Chronic stress produces an alteration in the activity of the hypothalamic pituitary adrenal (HPA) system, and the autonomic nervous system (ANS), which over time increase the risk of AD and also the incidence of cardiovascular disease (CVD) and risk factors, such as hypertension, obesity and type 2 diabetes, associated with cognitive impairment and AD. Considering the multi-factorial etiology of AD, understanding the complex interrelationships between different risk factors is of potential interest for designing adequate strategies for preventing, delaying the onset or slowing down the progression of this devastating disease. Thus, in this review we will explore the general mechanisms and evidence linking stress, cardiovascular disease and AD, and discuss the potential benefits of physical activity for AD by counteracting the negative effects of chronic stress, CVD and risk factors.

Normalized Cortisol Reactivity Predicts Future Neuropsychological Functioning in Children With Mild/Moderate Asthma

Cortisol reactivity to adrenocorticotropic hormone (ACTH) has been associated with neuropsychological processes including attention and memory in children with asthma. While cortisol reactivity to a psychological stressor is often considered a measure of current neuroendocrine functioning, this study examines the association of the cortisol reactivity and subsequent neuropsychological functioning. Using prospective data from the Childhood Asthma Management Program (CAMP), we explored the predictive ability of cortisol reactivity to ACTH and children's later attention and memory using traditional and an alternative cortisol reactivity (normalized cortisol) measures. Cortisol reactivity was assessed at study entry and 1-year follow-up, and neuropsychological functioning was assessed at 3-year follow-up. Cortisol reactivity was assessed through plasma cortisol concentrations collected at baseline (CORTBASELINE) and 30 min post-ACTH challenge (CORTPOST-A CTH). An alternative measure of cortisol reactivity was developed through post-ACTH stimulation cortisol, normalized by cortisol by baseline (CORTNORM -ACTH). CORT B ASELINE positively predicted year 3 attention, while CORTNORM -ACTH negatively predicted attention, suggesting convergence of cortisol variables in prediction of neuropsychological function. Year 1 CORTACTH positively predicted child memory at year 3; Year 1 CORTNORM-ACTH negatively predicted year 3 sustained attentions. These findings demonstrate that HPA reactivity, including the application of normalized cortisol reactivity, can predict subsequent neuropsychological functioning of children with mild to moderate asthma.

The relationship between loneliness and cognition in healthy older men and women: The role of cortisol

Loneliness has been associated with an increased risk of cognitive decline and dementia in older people, as well as a dysregulation of Hypothalamic-Pituitary-Adrenal (HPA) axis functioning. In addition, it has been suggested that women are more vulnerable to the negative effects of loneliness on health. Our aim was to analyze the effect of HPA-axis functioning as a mediator in the relationship between loneliness and cognitive function, and interactions depending on sex, in healthy older people. To do so, 86 healthy older people (52.3% female) from 60 to 80 years old (M = 67.44, SD = 4.37) completed the revised UCLA loneliness scale. A neuropsychological battery was administered to assess global cognition, processing speed, attention and executive function, working memory, and verbal memory immediate and delayed recall. Saliva samples were provided on two consecutive weekdays to obtain awakening and bedtime cortisol levels, the diurnal cortisol slope (DCS), and the area under the curve with respect to the ground (AUCg). Our results showed that loneliness was not directly associated with cognitive performance. Furthermore, loneliness was related to higher bedtime cortisol levels, but not to awakening cortisol, the DCS, or the AUCg. In addition, loneliness was associated with worse performance on attention and processing speed, executive function, and verbal memory immediate recall, via bedtime cortisol levels. Therefore, we suggest that HPA-axis functioning is one of the biological mechanisms that mediate the relationship between loneliness and poorer cognitive function. No sex differences were observed in these associations.

Associations between cortisol awakening response and resting electroencephalograph asymmetry

The cortisol awakening response (CAR), a rapid cortisol rise in the morning after awakening, has been proposed to provide energy to cope with daily demands and suggested to be associated with brain functions. Electroencephalogram (EEG) asymmetry studies have implicated asymmetric cortical activation, especially in frontal cortex, in approach-withdrawal motivation. In this study, we examined the relationship between the CAR and lateralized cortical activity under rest in 55 university male students. Saliva samples were collected at 0, 15, 30 and 60 min after awakening on the two consecutive workdays. The lateralized cortical activity at frontocentral sites was examined by alpha asymmetry score. The results showed that a higher CAR was positively associated with alpha asymmetry score, which indicated that the higher CAR is linked with more left-sided cortical activity at frontocentral sites under resting state. This association still existed even after controlling psychological and sleep quality variables. These results suggested that appropriately mobilizing energy resource storage after awakening revealed as CAR might be associated with goal-directed approach tendencies before any eventual stressful situation, characteristic of more left than right resting-state frontocentral cortical activity.

Dysregulation of the hypothalamic pituitary adrenal (HPA) axis and cognitive capability at older ages: individual participant meta-analysis of five cohorts

Evidence on the association between functioning of the hypothalamic pituitary adrenal (HPA) axis and cognitive capability at older ages is mixed. We undertook a systematic review (until October 2016) and individual participant data (IPD) meta-analysis to test if dysregulation of the HPA axis is associated with worse cognitive capability. Five cohort studies were included in the IPD meta-analysis of diurnal cortisol patterns with crystallised and fluid cognitive ability. Higher night time cortisol was associated with worse fluid ability (standardised coefficient per SD increase −0.063, 95% CI −0.124, −0.002, P = 0.04; I² = 79.9%; age and gender adjusted). A larger diurnal drop was associated with better fluid ability (standardised coefficient per SD increase 0.037, 95% CI 0.008, 0.065, P = 0.01; I² = 49.2%; age and gender adjusted). A bigger cortisol awakening response (CAR) was weakly associated with better fluid (P = 0.09; I² = 0.0%; age and gender adjusted) and crystallised (P = 0.10; I² = 0.0%; age and gender adjusted) ability. There is weak evidence that a greater diurnal decline of the HPA axis and a larger CAR are associated with improvements in cognition at older ages. As associations are cross-sectional, we cannot rule out reverse causation.

Exercise, the diurnal cycle of cortisol and cognitive impairment in older adults

Exercise has been shown to reduce the risk of developing Mild Cognitive Impairment and Alzheimer's disease as well as to improve cognition in healthy and cognitively impaired individuals. However, the mechanisms of these benefits are not well understood. The stress hypothesis suggests that the cognitive benefits attributed to exercise may partially be mediated by changes in the cortisol secretion pattern. Chronic stress may increase the risk of AD and exacerbate the cognitive deficits and brain pathology characteristic of the condition while physical activity has been shown to attenuate most of stress consequences and risk factors for AD. Initially, research on the effects of cortisol on cognition and physical activity focused on cortisol levels at one time point but the circadian pattern of cortisol secretion is complex and it is still unclear which aspects are most closely associated with cognitive function. Thus, the aim of this review was to analyze the exercise/stress/cognition hypothesis focusing on the effects of the diurnal cycle of cortisol on cognitive function and physical activity in older adults with and without cognitive impairment.

Stress-induced corticosterone secretion covaries with working memory in aging

A substantial literature details the relationship between age-related changes to the hypothalamic-pituitary-adrenal axis and deterioration of mnemonic functions that depend on the hippocampus. The relationship between adrenocortical status and other forms of memory that depend on the prefrontal cortex is less well understood in the context of advanced age. Here, we characterized performance of young adult and aged F344 rats on a prefrontal cortex-dependent working memory task and subsequently measured corticosterone (CORT) levels over the diurnal cycle and during exposure to an acute stressor. Our analyses revealed that aged rats with better working memory mounted a greater CORT response during acute stress exposure than either young adults or age-matched rats with impaired working memory. We also observed that age-related elevation of basal CORT levels is not associated with working memory performance. Jointly, these data reveal that the hypothalamic-pituitary-adrenal axis-mediated response to acute stress is positively associated with working memory in aging.

The cortisol awakening response predicts response inhibition in the afternoon of the same day

The cortisol awakening response (CAR) is the rapid increase of cortisol levels 30-45 min after awakening in the morning. Numerous studies have indicated the relationship between the CAR and cognition. However, little is known about daily variation in the CAR and cognitive function in healthy adults. The aim of the present study was to investigate whether the CAR predicted the response inhibition function on the same day in both behaviour and the dynamic time course of brain processing. The saliva samples of 47 healthy men were collected at three time points: immediately on awakening, 30 min and 45 min post-awakening in the morning. Participants performed a Go/NoGo task while electroencephalograms (EEG) were recorded in the afternoon of the same day. The results showed that a greater CAR was associated with a stronger N2. In the sub-group of CAR responders (n = 33) the CAR was negatively related to the false alarm rate of NoGo-trials. Our findings suggested that the CAR was predictive of the function of response inhibition in both the earlier cognitive step (i.e., conflict monitoring) and the behavioural performance of response inhibition on the same day in healthy men.

Elevated cortisol awakening response associated with early life stress and impaired executive function in healthy adult males

Experiencing early life stress (ELS) and subsequent dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis may play a role in the aetiology of mental health disorders. However, the exact mechanisms linking HPA-axis dysregulation with the development of psychopathology have not been fully delineated. Progress in this area is hampered by the complex and often conflicting associations found between markers of HPA-axis function and risk factors for mental health disorders such as impaired executive function (EF) and ELS. This study investigated the association of the cortisol awakening response (CAR) with ELS and EF in a healthy adult male population (n=109, aged 21-63). As previous inconsistencies in CAR and ELS association studies may be the result of not considering ELS-related factors such as cumulative exposure, type of stressor and developmental timing of ELS, these were also investigated. The main findings were that the CAR was significantly elevated in individuals reporting ELS compared to those reporting no ELS (p=0.007) and that an elevated CAR predicted poorer problem solving/planning (p=0.046). Cumulative exposure, type of stressor and developmental timing of ELS were also found to impact significantly on the CAR. These results suggest that ELS is associated with chronic changes in HPA-axis function and that these changes may be associated with impairments in problem solving/planning. Future work should investigate further the neurobiological mechanisms linking ELS, the CAR and EF and their role in conferring risk for the development of mental health disorders.

Moderating Effects of Cortisol on Neural-Cognitive Association in Cognitively Normal Elderly Subjects

Cortisol homeostasis is important for healthy brain and cognitive aging. The aim of the current study is to investigate the role of serum cortisol levels in the relationship between regional brain volumes and cognitive processing speed in a group of cognitively normal elderly subjects. Forty-one healthy elderly participants were from a parallel longitudinal study. The reported data in this study reflects baseline measurements. Whole-brain anatomical scanning was performed using a 3.0 Tesla Philips Medical Systems Achieva scanner. Cognitive processing speed was assessed by the digit-symbol and symbol search tests, from the Chinese version of the Wechsler Adult Intelligence Scale—third edition (WAIS-III). Serum cortisol levels (sampled in the late morning) were measured by ELISA kits. Whole-brain regression analysis revealed that serum cortisol levels positively predicted the white matter volumes (WMV) of the right thalamus, the gray matter volumes (GMV) of the left thalamus and right cerebellar tonsil, and negatively predicted the WMV and GMV of the left middle temporal gyrus (MTG) in 41 healthy elderly participants. Furthermore, serum cortisol significantly moderated the relationship between the GMV of the left MTG and processing speed, as well as the GMV of the left thalamus and processing speed. This study provided the first piece of evidence supporting serum cortisol levels in moderating the relationship between regional brain volumes and processing speed in healthy elderly subjects. This observation enriches our understanding of the role of cortisol in brain morphology and cognitive functioning.

Does the diurnal cycle of cortisol explain the relationship between physical performance and cognitive function in older adults?

Background

Regular physical activity is a promising strategy to treat and prevent cognitive decline. The mechanisms that mediate these benefits are not fully clear but physical activity is thought to attenuate the harmful effects of chronic psychological stress and hypercortisolism on cognition. However, the circadian pattern of cortisol secretion is complex and it is not known which aspects are most closely associated with increased cognitive function and better physical performance. This is the first study to simultaneously measure cognitive function, the diurnal cycle of salivary cortisol and physical performance in older adults, without cognitive impairment (n = 30) and with amnestic Mild Cognitive Impairment (aMCI) (n = 30).

Results

Regression analysis showed that better cognitive function was associated with better physical performance. A greater variance in cortisol levels across the day from morning to evening was associated with better cognitive function and physical performance.

Conclusions

The results support the idea that a more dynamic cortisol secretion pattern is associated with better cognitive function and physical performance even in the presence of cognitive impairment, but our results could not confirm a mediating role in this relationship.

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.

Memory performance is related to the cortisol awakening response in older people, but not to the diurnal cortisol slope

There are large individual differences in age-related cognitive decline. Hypothalamic-pituitary-adrenal axis (HPA-axis) functioning has been suggested as one of the mechanisms underlying these differences. This study aimed to investigate the relationships between the diurnal cortisol cycle, measured as the cortisol awakening response (CAR), and the diurnal cortisol slope (DCS) and the memory performance of healthy older people. To do so, we assessed the verbal, visual, and working memory performance of 64 participants (32 men) from 57 to 76 years old who also provided 14 saliva samples on two consecutive weekdays to determine their diurnal cortisol cycle. The CAR was linearly and negatively associated with verbal (significantly) and visual (marginally) memory domains, but not with working memory. Sex did not moderate these relationships. Furthermore, no associations were found between the DCS and any of the three memory domains assessed. Our results indicate that the two components of the diurnal cortisol cycle have different relationships with memory performance, with the CAR being more relevant than DCS in understanding the link from HPA-axis activity and regulation to different types of memory. These results suggest that the CAR is related to memory domains dependent on hippocampal functioning (i.e., declarative memory), but not to those that are more dependent on prefrontal cortex functioning (i.e., working memory).

Cortisol awakening response and cognitive performance in hypertensive and normotensive older people

Healthy older people with a cortisol awakening response (CAR) of decreased magnitude show worse frontal cortex-related cognitive performance. Systemic hypertension has been related to a CAR of decreased magnitude. Additionally, worse executive function and processing speed have been observed in older people with systemic hypertension. This is the first study to examine the relationship between the CAR (measured with six saliva samples at home on two consecutive weekdays) and cognitive performance, in both hypertensive (n=26) and normotensive (n=28) older people (from 56 to 78years old). Hypertensive participants showed lower morning cortisol secretion, and they also woke up earlier. No differences in CAR were observed. A CAR of decreased magnitude was related to worse executive function in both hypertensive and normotensive participants, but to slower processing speed only in normotensive participants. Being treated with antihypertensive for a longer period of time was related to a CAR of increased magnitude and better performance on executive function. Our findings suggest that earlier awakening time in hypertensive older people might underlie the lower overall morning cortisol secretion observed in previous studies. Additionally, this study confirms that a dysregulation of the CAR is related to worse executive function, and it extends this association to hypertensive older people. Finally, it is worth noting that hypertension may moderate the relationship between CAR and processing speed.

Cortisol Awakening Response and Walking Speed in Older People

In older people, less diurnal variability in cortisol levels has been consistently related to worse physical performance, especially to slower walking speed (WS). The cortisol awakening response (CAR) is a discrete component of the hypothalamic-pituitary-adrenal axis that has been related to several health problems, such as cardiovascular disease and/or worse performance on executive function and memory. The relationship between the CAR and physical performance in older people is poorly understood. In this study, in 86 older people (mean age = 64.42, SD = 3.93), we investigated the relationship between the CAR and WS, a commonly used measure of physical performance in the older population that has also been related to health problems, such as cardiovascular disease and executive function performance in older people. Additionally, we studied whether the relationship between the CAR and WS was independent from cortisol levels on awakening and several possible confounders. Results showed that a CAR of reduced magnitude (measured with 3 samples each day, for two consecutive days, and calculated as the area under the curve with respect to the increase), but not cortisol levels on awakening, was related to slower WS. In addition, this relationship was independent from cortisol levels on awakening. It is possible that a CAR of reduced magnitude would contribute to less diurnal cortisol variability, affecting physical performance. Additionally, it is possible that a CAR of reduced magnitude affects WS through a possible negative effect on executive function, or that the association between the CAR and WS is due to the fact that both are related to similar health problems and to changes in cognitive performance in older people.

The cortisol awakening response and cognition across the adult lifespan

Although the hippocampus is thought to play a central role in the regulation of the cortisol awakening response (CAR), results from past studies examining the relationship between the CAR and hippocampal-mediated memory and cognition have been mixed. Inconsistent findings may be due to the use of cortisol samples collected on only 1-2days since reduced sampling can permit unstable situational factors to bias results. We used cortisol assessments from 10 consecutive days to test the relationship of the CAR to episodic memory, working memory, and processing speed in a sample of healthy young, middle-aged, and older adults (age range: 23-79years; N=56). We tested if the relationship between the CAR and cognition would depend upon age and also tested if other cortisol measures, specifically waking cortisol, diurnal cortisol output (i.e., area under the curve) and diurnal cortisol slope (linear and quadratic), would be related to cognition. We found that a more positive CAR slope was related to better episodic memory and that this relationship did not depend upon age. The CAR was not significantly related to working memory. The relationship of the CAR to processing speed was not significant when using a CAR measure that corrected for non-compliant cortisol sampling. We also found that higher waking cortisol was significantly related to better working memory, but not episodic memory or processing speed. Neither diurnal cortisol output nor diurnal linear cortisol slope was significantly related to cognitive functioning. Future work should investigate the mechanisms underpinning the relationship of the cortisol awakening process to cognitive functioning.

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.

The cortisol awakening response is associated with performance of a serial sequence reaction time task

There is emerging evidence of a relationship between the cortisol awakening response (CAR) and the neural mechanisms underlying learning and memory. The aim of this study was to determine whether the CAR is associated with acquisition, retention and overnight consolidation or improvement of a serial sequence reaction time task. Salivary samples were collected at 0, 15, 30 and 45 min after awakening in 39 healthy adults on 2 consecutive days. The serial sequence reaction time task was repeated each afternoon. Participants completed the perceived stress scale and provided salivary samples prior to testing for cortisol assessment. While the magnitude of the CAR (Z score) was not associated with either baseline performance or the timed improvement during task acquisition of the serial sequence task, a positive correlation was observed with reaction times during the stable performance phase on day 1 (r=0.373, p=0.019). Residuals derived from the relationship between baseline and stable phase reaction times on day 1 were used as a surrogate for the degree of learning: these residuals were also correlated with the CAR mean increase on day 1 (r=0.357, p=0.048). Task performance on day 2 was not associated with the CAR obtained on this same day. No association was observed between the perceived stress score, cortisol at testing or task performance. These data indicate that a smaller CAR in healthy adults is associated with a greater degree of learning and faster performance of a serial sequence reaction time task. These results support recognition of the CAR as an important factor contributing to cognitive performance throughout the day.

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.

A study of cognitive functions in female elderly patients with osteoporosis: a multi-center cross-sectional study

OBJECTIVES

To investigate changes of cognitive performances in female elderly patients with osteoporosis and to determine whether any impairments can be attributed to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis.

METHODS

This cross-sectional study included 277 postmenopausal women, who were divided into an osteoporosis patients group (n = 170) and an age, gender and educational history matching control group (n = 107). All the subjects completed a set of neuropsychological tests for the elderly for cognitive assessment, which included measures of executive function, episodic memory, attention and processing speed, semantic memory, and visuospatial construction. Blood biomarkers for osteoporosis, as well as diurnal rhythms of cortisol levels were used as cognitive performance correlation parameters in linear multivariate regression analyses.

RESULTS

Individuals with osteoporosis had poorer cognitive scores (P < 0.001). When dividing the osteoporosis patients according to their Mini-Mental State Examination scores into mild cognitive impairment (MCI) and normal cognitive (NC) performance groups, Auditory Verbal Learning trial 1-5 scores were lower (P = 0.006) and Trail Making Test-A scores were higher (P = 0.05) in the MCI compared to the NC group. Further comparison of the MCI and NC groups revealed that declarative memory was inversely associated with cortisol levels (P < 0.001), but this association became marginal when 25-hydroxy vitamin D was included in the linear multivariate regression analyses (P = 0.06).

CONCLUSIONS

Patients with osteoporosis are prone to cognitive impairments especially declarative memory deficits. The cognitive impairment may be the result of HPA axis dysregulation but 25-hydroxy vitamin D serum concentrations might be compensatory or even a potent contributing factor.

High cortisol awakening response is associated with impaired error monitoring and decreased post-error adjustment

The cortisol awakening response (CAR), a rapid increase in cortisol levels following morning awakening, is an important aspect of hypothalamic-pituitary-adrenocortical axis activity. Alterations in the CAR have been linked to a variety of mental disorders and cognitive function. However, little is known regarding the relationship between the CAR and error processing, a phenomenon that is vital for cognitive control and behavioral adaptation. Using high-temporal resolution measures of event-related potentials (ERPs) combined with behavioral assessment of error processing, we investigated whether and how the CAR is associated with two key components of error processing: error detection and subsequent behavioral adjustment. Sixty university students performed a Go/No-go task while their ERPs were recorded. Saliva samples were collected at 0, 15, 30 and 60 min after awakening on the two consecutive days following ERP data collection. The results showed that a higher CAR was associated with slowed latency of the error-related negativity (ERN) and a higher post-error miss rate. The CAR was not associated with other behavioral measures such as the false alarm rate and the post-correct miss rate. These findings suggest that high CAR is a biological factor linked to impairments of multiple steps of error processing in healthy populations, specifically, the automatic detection of error and post-error behavioral adjustment. A common underlying neural mechanism of physiological and cognitive control may be crucial for engaging in both CAR and error processing.

The cortisol awakening response predicts same morning executive function: results from a 50-day case study

A relationship between individual differences in trait estimates of the cortisol-awakening response (CAR) and indices of executive function (EF) has been reported. However, it is difficult to determine causality from such studies. The aim of the present study was to capitalise upon state variation in both variables to seek stronger support for causality by examining daily co-variation. A 50 days researcher-participant case study was employed, ensuring careful adherence to the sampling protocol. A 24-year-old healthy male collected saliva samples and completed an attention-switching index of EF on the morning of each study day. Subsidiary control measures included wake time, sleep duration, morning fatigue, and amount of prior day exercise and alcohol consumption. As the CAR preceded daily measurement of EF, we hypothesised that, over time, a greater than average CAR would predict better than average EF. This was confirmed by mixed regression modelling of variation in cortisol concentrations, which indicated that the greater the increase in cortisol concentrations from 0 to 30 min post-awakening (CAR) the better was subsequent EF performance at 45 min post-awakening (t = 2.29, p = 0.024). This effect was independent of all potential confounding measures. Results are discussed in terms of implications for the understanding of the relationship between the CAR and the cognitive function, and the previously suggested role of the CAR in "boosting" an individual's performance for the day ahead.

The effect of progressive muscle relaxation on daily cortisol secretion

Abbreviated progressive muscle relaxation (APMR) is a much used stress-management technique. Its efficacy relevant to placebo control is already established in the literature and the primary aim of the present study was to ascertain whether its proven impact on psychological stress measures is matched by a decrease in prevailing levels of the stress-associated hormone cortisol, using accurate and robust measurement based on multiple sampling of full diurnal cortisol secretion profiles. First-year university students can face significant stress in adjustment to academic demands and immersion in a novel social network and provided a convenient study population. One hundred and one first-year students completed APMR with prevailing stress levels assessed a week before and after intervention. Both cortisol and self-report measures were significantly reduced post-intervention by 8% and 10%, respectively. The efficacy of the intervention was independent of, and not modulated by neuroticism, gender, age and smoking status. We also demonstrated that cortisol reduction was unlikely to have been a consequence of adaptation to any initial cortisol elevation prompted by the challenge of the demanding saliva collection protocol. We conclude that the efficacy of APMR in this population extends to reduction in biologically expressed stress levels as well as levels based solely on self-report.

Day differences in the cortisol awakening response predict day differences in synaptic plasticity in the brain

The cortisol awakening response (CAR) is the most prominent, dynamic and variable part of the circadian pattern of cortisol secretion. Despite this, its precise purpose is unknown. Aberrant patterns of the CAR are associated with impaired physical and mental health and reduced cognitive function, suggesting that it may have a pervasive role or roles. It has been suggested that the CAR primes the brain for the expected demands of the day but the mechanisms underlying this process are unknown. We examined temporal covariation of the CAR and rapid transcranial magnetic stimulation (rTMS)-induced long term depression (LTD)-like responses in the motor cortex. Plasticity was evaluated across 180 measures from five time points on four sessions across nine healthy researcher participants, mean age 25 ± 2.5 years. Plasticity estimates were obtained in the afternoon after measurement of the CAR on 4 days, at least 3 days apart. As both CAR magnitude and rTMS-induced responses are variable across days, we hypothesized that days with larger than individual average CARs would be associated with a greater than individual average plasticity response. This was confirmed by mixed regression modelling where variation in the CAR predicted variation in rTMS-induced responses (df: 1, 148.24; F: 10.41; p = 0.002). As the magnitude of the CAR is regulated by the "master" circadian CLOCK, and synaptic plasticity is known to be modulated by peripheral "slave" CLOCK genes, we suggest that the CAR may be a mediator between the master and peripheral circadian systems to entrain daily levels of synaptic plasticity.

Increased cortisol levels in hair of recent Ecstasy/MDMA users

Previous research has revealed an acute 8-fold increase in salivary cortisol following self-administrated Ecstasy/MDMA in dance clubbers. It is currently not known to what extent repeated usage impacts upon activity of the hypothalamic-pituitary-adrenal axis over a more prolonged period of time. This study investigated the integrated cortisol levels in 3-month hair samples from recent Ecstasy/MDMA users and non-user controls. One hundred and one unpaid participants (53 males, 48 females; mean age 21.75 years) completed the University of East London recreational drug use questionnaire, modified to cover the past 3-months of usage. They comprised 32 light recent Ecstasy/MDMA users (1-4 times in last 3 months), 23 recent heavy MDMA users (+5 times in last 3 months), and 54 non-user controls. Volunteers provided 3 cm hair samples for cortisol analysis. Hair cortisol levels were observed to be significantly higher in recent heavy MDMA users (mean = 55.0 ± 80.1 pg/mg), compared to recent light MDMA users (19.4 ± 16.0 pg/mg; p=0.015), and to non-users (13.8 ± 6.1 pg/mg; p<0.001). Hence the regular use of Ecstasy/MDMA was associated with almost 4-fold raised hair cortisol levels, in comparison with non-user controls. The present results are consistent with the bio-energetic stress model for Ecstasy/MDMA, which predicts that repeated stimulant drug use may increase cortisol production acutely, and result in greater deposits of the hormone in hair. These data may also help explain the neurocognitive, psychiatric, and other psychobiological problems of some abstinent users. Future study design and directions for research concerning the psychoneuroendocrinological impact of MDMA are also discussed.

The relation of the cortisol awakening response and prospective memory functioning in young children

Recent research suggests that the cortisol awakening response (CAR) is linked to cognitive functions depending on hippocampal and frontal cortex circuits and may possibly be modulated by prospective memory (PM). However, the link between the CAR and PM abilities has not been investigated so far. Addressing this open issue, we report data from 97 children aged 37-87 months. Salivary cortisol levels were assessed 0 and 30 min post-awakening over three study days. Thereby a valid CAR measurement was ensured by using objective measures of awakening and sampling times. A game-like task served as behavioral measure of PM performance. Bayesian analysis revealed a positive association between children's PM performance and the CAR, with better PM performance being related to a greater CAR. This association persisted after controlling for age. Overall, the current finding supports the prediction that PM functioning may be linked to the CAR, possibly as both the CAR and PM rely on a common neurophysiological basis.

Causes and consequences of age-related steroid hormone changes: insights gained from nonhuman primates

Similar to humans, rhesus macaques (Macaca mulatta) are large, long-lived diurnal primates, and show similar age-related changes in the secretion of many steroid hormones, including oestradiol, testosterone, cortisol and dehydroepiandrosterone (DHEA). Consequently, they represent a pragmatic animal model in which to examine the mechanisms by which these steroidal changes contribute to perturbed sleep-wake cycles and cognitive decline in the elderly. Using remote serial blood sampling, we have found the circulating levels of DHEA sulphate, as well as oestradiol and testosterone, decline markedly in old monkeys. Furthermore, using the real-time polymerase chain reaction, we have shown that the genes for the enzymes associated with the conversion of DHEA to oestradiol and testosterone (3β-hydroxysteroid dehydrogenase, 17β-hydroxysteroid dehydrogenase, and aromatase) are highly expressed in brain areas associated with cognition and behaviour, including the hippocampus, prefrontal cortex and amygdala. Taken together, these findings suggest that the administration of supplementary DHEA in the elderly may have therapeutic potential for cognitive and behavioural disorders, although with fewer negative side effects outside of the central nervous system. To test this, we have developed a novel steroid supplementation paradigm for use in old animals; this involves the oral administration of DHEA and testosterone at physiologically relevant times of the day to mimic the circadian hormone patterns observed in young adults. We are currently evaluating the efficacy of this steroid supplementation paradigm with respect to reversing age-associated disorders, including perturbed sleep-wake cycles and cognitive decline, as well as an impaired immune response.

Delays of 5-15 min between awakening and the start of saliva sampling matter in assessment of the cortisol awakening response

Linking psychosocial measures to the cortisol awakening response (CAR) demands accurate saliva sampling times. Monitoring adherence to the saliva sampling protocol requires electronic monitoring of both awakening and sampling times since self-reported times are inaccurate. Delays greater than 15 min between awakening and commencement of saliva sampling reduce CAR magnitude. Less delay has been judged tolerable but remains unexplored for different magnitude measures, and for timing of the CAR peak. Study 1: Fifty healthy females (21 ± 4 years) were instructed to collect saliva on four days at 0, 15, 30 and 45 min post-awakening (samples 1-4). Both self-reported awakening and sampling times were electronically monitored using actigraphy and track caps. Self-reported awakening was later than actigraph estimated awakening (median difference of 4 min). Estimates of CAR magnitude were significantly greater on non-adherent days (delay of 5-15 min) compared to adherent days (delay<5 min). On non-adherent compared to adherent days cortisol on average peaked earlier, at sample 3 rather than at sample 4. Study 2: Accurately timed cortisol values were obtained in an intensive investigation of 10 participants who collected saliva on 2 days every 5 min for 30 min post-awakening. Cortisol did not significantly increase until 10 min post-awakening, suggesting a time lag may be typical between awakening and observation of a cortisol increase. We conclude that moderate delays between awakening and collection of saliva samples previously considered tolerable result in erroneous estimation of CAR magnitude and timing of the peak. These results are attributed to an approximate 10 min time lag between awakening and the start of the cortisol rise. The absence of this latent period in calculations leads to overestimation of the CAR magnitude on moderately non-adherent sampling days. These findings, if more universally generalizable, will further theoretical understanding of the physiology of the CAR, but are methodologically challenging for researchers since self-reported awakening times are not accurate enough to override the concerns raised. However accurate electronic measurement of adherence to protocol would enable sampling delays to be taken into account in computing CAR estimates.

Age-dependent and gender-dependent regulation of hypothalamic-adrenocorticotropic-adrenal axis

Tightly regulated output of glucocorticoids is critical to maintaining immune competence, the structure of neurons, muscle, and bone, blood pressure, glucose homeostasis, work capacity, and vitality in the human and experimental animal. Age, sex steroids, gender, stress, body composition, and disease govern glucocorticoid availability through incompletely understood mechanisms. According to an ensemble concept of neuroendocrine regulation, successful stress adaptations require repeated incremental signaling adjustments among hypothalamic corticotropin-releasing hormone and arginine vasopressin, pituitary adrenocorticotropic hormone, and adrenal corticosteroids. Signals are transduced via (positive) feedforward and (negative) feedback effects. Age and gonadal steroids strongly modulate stress-adaptive glucocorticoid secretion by such interlinked pathways.