For whom the bell (curve) tolls: cortisol rapidly affects memory retrieval by an inverted U-shaped dose-response relationship

Parenting predicts Strange Situation cortisol reactivity among children adopted internationally

The functioning of the hypothalamic pituitary adrenal (HPA) axis can be altered by adverse early experiences. Recent studies indicate that children who were adopted internationally after experiencing early institutional rearing and unstable caregiving exhibit blunted HPA reactivity to stressful situations. The present study examined whether caregiving experiences post-adoption further modulate children's HPA responses to stress. Parental sensitivity during naturalistic parent-child play interactions was assessed for 66 children (M age = 17.3 months, SD = 4.6) within a year of being adopted internationally. Approximately 8 months later, children's salivary cortisol levels were measured immediately before as well as 15 and 30 min after a series of brief separations from the mother in an unfamiliar laboratory setting. Latent growth curve modeling indicated that experiencing more parental sensitivity predicted increased cortisol reactivity to the stressor. Although half the families received an intervention designed to improve parental sensitivity, the intervention did not significantly alter children's cortisol outcomes. These findings suggest that post-adoption parental sensitivity may help normalize the HPA response to stress among children adopted internationally.

Stress-related cortisol responsivity modulates prospective memory

It is known that there is inter-individual variation in behavioural and physiological stress reactions to the same stressor. The present study aimed to examine the impact of cortisol responsivity on performance in a complex real life-like prospective memory (PM) paradigm by a re-analysis of data published previously, with a focus on the taxonomy of cognitive dimensions of PM. Twenty-one male subjects were stressed with the Socially Evaluated Cold Pressor Test (SECPT) before the planning of intentions. Another group of 20 males underwent a control procedure. Salivary cortisol was measured to assess the intensity of the biological stress response. Additionally, participants rated the subjective experience of stress on a 5-point rating scale. Stressed participants were post-hoc differentiated in high (n = 11) and low cortisol responders (n = 10). Cortisol niveau differed significantly between the two groups, whereas subjective stress ratings did not. PM performance of low cortisol responders was stable across time and the PM performance of controls declined. High cortisol responders showed a nominally weaker PM retrieval across the early trails and significantly improved only on the last trial. The data demonstrate for the first time that participants with a low cortisol responsivity may benefit from stress exposure before the planning phase of PM. PM performance of high cortisol responders shows a more inconsistent pattern, which may be interpreted in the sense of a recency effect in PM retrieval. Alternatively, high cortisol responses may have a deteriorating effect on PM retrieval, which disappeared on the last trials of the task as a result of the decrease of cortisol levels across time. Importantly, the data also demonstrate that the intensity of cortisol responses does not necessarily correspond to the intensity of the mental experience of stress.

Linking cortisol response with gene expression in fish exposed to gold nanoparticles

Fish exposure to environmental stressors (e.g. chemicals, hypoxia, temperature) induce responses enabling them to cope with alterations in their environment. A stress response involves a wide array of changes, from molecular to physiological and behavioural, set to counteract the effect of the stressor and recover homeostatic equilibrium. Among other processes, there is activation of the hypothalamus-pituitary-interrenal (HPI) axis, resulting in stimulation of the steroidogenic pathway and release of cortisol, important mediator of the adaptive response to stress. The purpose of this study was to evaluate if exposure of a marine teleost (gilthead sea bream) to gold nanoparticles (AuNP) could interfere with the HPI axis eliciting an acute stress response and how this response would be linked with alterations in the mRNA levels of target genes in the head kidney, important centre of endocrine response in fish. Fish were exposed via water, for 96h, to four concentrations (0, as control, 4, 80 and 1600μg⋅L^-1) of 40nm spherical AuNP, covered with two different types of coatings (citrate and PVP). At the end of the exposure, fish were anesthetized and blood and the head kidney sampled. Results showed that exposure to 1600μg⋅L^-1 AuNP-citrate and 80μg⋅L^-1 AuNP-PVP increased plasma cortisol levels, compared to controls, but caused no change in glucose levels. AuNP modulated the expression of target genes related to oxidative stress, cell-tissue repair, immune function and apoptosis in the head kidney of fish. The patterns of response were distinct for the two coatings tested. Unlike AuNP-citrate, AuNP-PVP elicited an inverted U-shaped response. Present findings demonstrated that AuNP were able to activate the fish HPI axis and alter a battery of related molecular markers in the head kidney.

Hypothalamic-pituitary-adrenal axis activity and cognition in major depression: The role of remission status

OBJECTIVES

Neuropsychological deficits and hypothalamic-pituitary-adrenal (HPA) axis dysfunction have been described in major depressive disorder (MDD). We conducted an exploratory study to investigate the role of remission status in the relationship between HPA axis and cognition in MDD.

METHODS

Ninety-seven MDD patients (44 remitted, 53 non-remitted) and 97 healthy controls (HC) were evaluated. We measured verbal and visual memory, working memory, processing speed, attention, and executive function. Three HPA axis measures were assessed: cortisol awakening response (CAR), diurnal cortisol slope, and cortisol suppression ratio with 0.25mg of dexamethasone (DSTR). Multiple linear regression analyses were performed to study the relationship between cortisol measures and cognition while controlling for potential confounders. We conducted an overall analysis in all participants to compare both MDD-remitted and MDD non-remitted groups with respect to HC. Another analysis including MDD patients only was used to explore a moderating effect by remission status.

RESULTS

MDD patients showed poorer cognitive performance compared with HC, without significant differences between remitters and non-remitters. Cortisol measures did not differ between remitters and non-remitters. Although most HPA axis measures were not associated with cognitive dysfunction, we found significant associations between cognitive performance in MDD-remitters and cortisol measures for visual memory, processing speed and executive function. A significant moderating effect for remission status was found between cortisol diurnal slope (but neither CAR nor DSTR) and performance in processing speed or executive function.

CONCLUSIONS

Remission status in MDD appears to moderate the association between some cognitive domains (processing speed and executive function) and HPA axis activity.

Memory under stress: from single systems to network changes

Stressful events have profound effects on learning and memory. These effects are mainly mediated by catecholamines and glucocorticoid hormones released from the adrenals during stressful encounters. It has been known for long that both catecholamines and glucocorticoids influence the functioning of the hippocampus, a critical hub for episodic memory. However, areas implicated in other forms of memory, such as the insula or the dorsal striatum, can be affected by stress as well. Beyond changes in single memory systems, acute stress triggers the reconfiguration of large scale neural networks which sets the stage for a shift from thoughtful, 'cognitive' control of learning and memory toward more reflexive, 'habitual' processes. Stress-related alterations in amygdala connectivity with the hippocampus, dorsal striatum, and prefrontal cortex seem to play a key role in this shift. The bias toward systems proficient in threat processing and the implementation of well-established routines may facilitate coping with an acute stressor. Overreliance on these reflexive systems or the inability to shift flexibly between them, however, may represent a risk factor for psychopathology in the long-run.

Hypothalamic-pituitary-adrenal axis measures and cognitive abilities in early psychosis: Are there sex differences?

INTRODUCTION

Measures of hypothalamic-pituitary-adrenal (HPA) axis activity such as increased diurnal cortisol levels or a blunted cortisol awakening response (CAR) have been associated with cognitive impairments in people with psychotic disorders. We aimed to explore whether there are sex differences in the relationship between HPA axis measures and cognition in early psychosis (EP).

METHODS

60 EP outpatients and 50 healthy subjects (HS) were assessed with the MATRICS Consensus Cognitive Battery. Saliva cortisol levels were determined at the neuropsychological assessment and on another day at 6 sampling times: awakening; 30' and 60' post-awakening; and 10:00h, 23:00h and 10:00h the day after the administration of 0.25mg of dexamethasone, which occurred at 23:00h. Three HPA axis measures were calculated: CAR, cortisol diurnal slope and cortisol suppression ratio of the dexamethasone suppression test (DST). Multiple linear regression analyses were conducted to explore the relationship between HPA axis measures and cognitive tasks while adjusting for covariates (education level, smoking, cannabis use, and cortisol levels at the cognitive assessment). Interactions between female sex, EP diagnosis and HPA axis measures were examined.

RESULTS

An increased CAR was associated with a poorer cognitive performance in EP women in processing speed and verbal memory. In contrast, a more flattened diurnal cortisol slope was associated with poorer functioning in the spatial working memory of EP women. DST suppression ratio was associated with better visual memory, without sex differences.

CONCLUSIONS

Our study suggests that there are sex differences in the relationship between HPA axis measures and cognitive abilities in EP.

A review of fundamental principles for animal models of DOHaD research: an Australian perspective

Epidemiology formed the basis of ‘the Barker hypothesis’, the concept of ‘developmental programming’ and today’s discipline of the Developmental Origins of Health and Disease (DOHaD). Animal experimentation provided proof of the underlying concepts, and continues to generate knowledge of underlying mechanisms. Interventions in humans, based on DOHaD principles, will be informed by experiments in animals. As knowledge in this discipline has accumulated, from studies of humans and other animals, the complexity of interactions between genome, environment and epigenetics, has been revealed. The vast nature of programming stimuli and breadth of effects is becoming known. As a result of our accumulating knowledge we now appreciate the impact of many variables that contribute to programmed outcomes. To guide further animal research in this field, the Australia and New Zealand DOHaD society (ANZ DOHaD) Animals Models of DOHaD Research Working Group convened at the 2nd Annual ANZ DOHaD Congress in Melbourne, Australia in April 2015. This review summarizes the contributions of animal research to the understanding of DOHaD, and makes recommendations for the design and conduct of animal experiments to maximize relevance, reproducibility and translation of knowledge into improving health and well-being.

True alignment of preclinical and clinical research to enhance success in CNS drug development: a review of the current evidence

Central nervous system pharmacological research and development has reached a critical turning point. Patients suffering from disorders afflicting the central nervous system are numerous and command significant attention from the pharmaceutical industry. However, given the numerous failures of promising drugs, many companies are no longer investing in or, indeed, are divesting from this therapeutic area. Central nervous system drug development must change in order to develop effective therapies to treat these patients. Preclinical research is a cornerstone of drug development; however, it is frequently criticised for its lack of predictive validity. Animal models and assays can be shown to be more predictive than reported and, on many occasions, the lack of thorough preclinical testing is potentially to blame for some of the clinical failures. Important factors such as translational aspects, nature of animal models, variances in acute versus chronic dosing, development of add-on therapies and understanding of the full dose-response relationship are too often neglected. Reducing the attrition rate in central nervous system drug development could be achieved by addressing these important questions before novel compounds enter the clinical phase. This review illustrates the relevance of employing these criteria to translational central nervous system research, better to ensure success in developing new drugs in this therapeutic area.

Anxiolytic Treatment Impairs Helping Behavior in Rats

Despite decades of research with humans, the biological mechanisms that motivate an individual to help others remain poorly understood. In order to investigate the roots of pro-sociality in mammals, we established the helping behavior test, a paradigm in which rats are faced with a conspecific trapped in a restrainer that can only be opened from the outside. Over the course of repeated test sessions, rats exposed to a trapped cagemate learn to open the door to the restrainer, thereby helping the trapped rat to escape (Ben-Ami Bartal et al., 2011). The discovery of this natural behavior provides a unique opportunity to probe the motivation of rodent helping behavior, leading to a deeper understanding of biological influences on human pro-sociality. To determine if an affective response motivates door-opening, rats receiving midazolam, a benzodiazepine anxiolytic, were tested in the helping behavior test. Midazolam-treated rats showed less helping behavior than saline-treated rats or rats receiving no injection. Yet, midazolam-treated rats opened a restrainer containing chocolate, highlighting the socially specific effects of the anxiolytic. To determine if midazolam interferes with helping through a sympatholytic effect, the peripherally restricted beta-adrenergic receptor antagonist nadolol was administered; nadolol did not interfere with helping. The corticosterone response of rats exposed to a trapped cagemate was measured and compared to the rats’ subsequent helping behavior. Rats with the greatest corticosterone responses showed the least helping behavior and those with the smallest responses showed the most consistent helping at the shortest latency. These results are discussed in terms of their implications for the interaction between stress and pro-social behavior. Finally, we observed that door-opening appeared to be reinforcing. A novel analytical tool was designed to interrogate the pattern of door-opening for signs that a rat’s behavior on one session influenced his behavior on the next session. Results suggest that helping a trapped rat has a greater motivational value than does chocolate. In sum, this series of experiments clearly demonstrates the fundamental role of affect in motivating pro-social behavior in rodents and the need for a helper to resonate with the affect of a victim.

Oncologists' non-verbal behavior and analog patients' recall of information

Background Information in oncological consultations is often excessive. Those patients who better recall information are more satisfied, less anxious and more adherent. Optimal recall may be enhanced by the oncologist's non-verbal communication. We tested the influence of three non-verbal behaviors, i.e. eye contact, body posture and smiling, on patients' recall of information and perceived friendliness of the oncologist. Moreover, the influence of patient characteristics on recall was examined, both directly or as a moderator of non-verbal communication. Material and methods Non-verbal communication of an oncologist was experimentally varied using video vignettes. In total 194 breast cancer patients/survivors and healthy women participated as 'analog patients', viewing a randomly selected video version while imagining themselves in the role of the patient. Directly after viewing, they evaluated the oncologist. From 24 to 48 hours later, participants' passive recall, i.e. recognition, and free recall of information provided by the oncologist were assessed. Results Participants' recognition was higher if the oncologist maintained more consistent eye contact (β = 0.17). More eye contact and smiling led to a perception of the oncologist as more friendly. Body posture and smiling did not significantly influence recall. Older age predicted significantly worse recognition (β = -0.28) and free recall (β = -0.34) of information. Conclusion Oncologists may be able to facilitate their patients' recall functioning through consistent eye contact. This seems particularly relevant for older patients, whose recall is significantly worse. These findings can be used in training, focused on how to maintain eye contact while managing computer tasks.

Effects of basal and acute cortisol on cognitive flexibility in an emotional task switching paradigm in men

The stress hormone cortisol is assumed to influence cognitive functions. While cortisol-induced alterations of declarative memory in particular are well-investigated, considerably less is known about its influence on executive functions. Moreover, most research has been focused on slow effects, and rapid non-genomic effects have not been studied. The present study sought to investigate the impact of acute cortisol administration as well as basal cortisol levels on cognitive flexibility, a core executive function, within the non-genomic time frame. Thirty-eight healthy male participants were randomly assigned to intravenously receive either cortisol or a placebo before performing a task switching paradigm with happy and angry faces as stimuli. Cortisol levels were measured at six points during the experiment. Additionally, before the experiment, basal cortisol measures for the cortisol awakening response were collected on three consecutive weekdays immediately following awakening and 30, 45, and 60min after. First and foremost, results showed a pronounced impact of acute and basal cortisol on reaction time switch costs, particularly for angry faces. In the placebo group, low basal cortisol was associated with minimal switch costs, whereas high basal cortisol was related to maximal switch costs. In contrast, after cortisol injection, basal cortisol levels showed no impact. These results show that cognitive flexibility-enhancing effects of acute cortisol administration are only seen in men with high basal cortisol levels. This result supports the context dependency of cortisol administration and shows the relevance of taking basal cortisol levels into account.

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.

From Memory Impairment to Posttraumatic Stress Disorder-Like Phenotypes: The Critical Role of an Unpredictable Second Traumatic Experience

Arousal and stress critically regulate memory formation and retention. Increasing levels of stress produce an inverted U-shaped effect on cognitive performance, including the retention of explicit memories, and experiencing a severe stress during a traumatic event may lead to posttraumatic stress disorder (PTSD). The molecular mechanisms underlying the impairing effect of a severe stress on memory and the key contribution of traumatic experiences toward the development of PTSD are still unknown. Here, using increasing footshock intensities in an inhibitory avoidance paradigm, we reproduced the inverted U-shaped curve of memory performance in rats. We then show that the inverted U profile of memory performance correlates with an inverted U profile of corticosterone level in the circulation and of brain-derived neurotrophic factor, phosphorylated tropomyosin-receptor kinase B, and methyl CpG binding protein in the dorsal hippocampus. Furthermore, training with the highest footshock intensity (traumatic experience) led to a significant elevation of hippocampal glucocorticoid receptors. Exposure to an unpredictable, but not to a predictable, highly stressful reminder shock after a first traumatic experience resulted in PTSD-like phenotypes, including increased memory of the trauma, high anxiety, threat generalization, and resistance to extinction. Systemic corticosterone injection immediately after the traumatic experience, but not 3 d later, was sufficient to produce PTSD-like phenotypes. We suggest that, although after a first traumatic experience a suppression of the corticosterone-dependent response protects against the development of an anxiety disorder, experiencing more than one trauma (multiple hits) is a critical contributor to the etiology of PTSD.

Free thyroxine levels are associated with cognitive changes in individuals with a first episode of psychosis: A prospective 1-year follow-up study

The results of previous cross-sectional studies suggest that free thyroxine (FT4) levels are associated with cognitive abilities (particularly attention/vigilance) during the early stages of psychosis. We aimed to explore whether hypothalamic-pituitary-thyroid hormones predict cognitive changes in a 1-year longitudinal study following first episodes of psychosis (FEP). We studied 36 FEP patients and a control group of 50 healthy subjects (HS). Plasma levels of thyroid-stimulating hormone (TSH) and FT4 were measured. Cognitive assessment was performed with the MATRICS Cognitive Consensus Cognitive Battery (MCCB). FEP patients were assessed twice (baseline and after 1year), whereas HS were assessed only once. We compared cognitive changes at 1year between three groups based on baseline FT4 levels: 1) lowest quartile (Q1, FT4<1.16ng/dL); 2) medium quartiles (Q2-Q3, FT4 1.16-1.54ng/dL); and 3) highest quartile (Q4, FT4>1.54ng/dL). No differences in TSH or FT4 levels were found between HS and FEP patients. All participants had FT4 levels within the normal range. HS outperformed FEP patients in all cognitive tasks. In relation to the relationship between FT4 levels and cognitive changes, a U-shaped pattern was observed: FEP patients from the middle quartiles (Q2-Q3) improved in attention/vigilance, whereas both extreme quartiles (Q1 and Q4) showed a worsening in this cognitive domain over time. Patients with lower FT4 (Q1) showed poorer baseline attention; therefore, lower baseline FT4 levels predicted a poorer prognosis in terms of attention performance. Our study suggests that baseline FT4 levels are associated with changes in attention and vigilance performance over one year in FEP patients.

Cortisol and stimulus-induced arousal level differentially impact memory for items and backgrounds

Most studies examine the effects of stress on memory for visual information test memory for entire scenes. However, arousal levels may differentially influence memory for backgrounds as opposed to items. Participants encoded scenes that included a negative-high-arousal, negative-moderate-arousal, or neutral item on a neutral background. After a 30-minute (Experiment 1) or 48-hour delay (Experiment 2), participants underwent a stressor or control task while heart rate was recorded. A recognition memory task was then given with items and backgrounds presented separately. High-arousal images had a greater detriment in background memory than moderate-arousal images. Further, though there was evidence that change in cortisol level at retrieval was associated with impaired memory for items, it was not associated with detriments in background memory. Increased heart rate was associated with impaired memory for both items and backgrounds. This suggests that the level of sympathetic and cortisol reactivity differentially affects memory for items and backgrounds.

Waterborne Risperidone Decreases Stress Response in Zebrafish

The presence of drugs and their metabolites in surface waters and municipal effluents has been reported in several studies, but its impacts on aquatic organisms are not yet well understood. This study investigated the effects of acute exposure to the antipsychotic risperidone on the stress and behavioral responses in zebrafish. It became clear that intermediate concentration of risperidone inhibited the hypothalamic-pituitary-interrenal axis and displayed anxiolytic-like effects in zebrafish. The data presented here suggest that the presence of this antipsychotic in aquatic environments can alter neuroendocrine and behavior profiles in zebrafish.

Labrador tea (Rhododendron groenlandicum) attenuates insulin resistance in a diet-induced obesity mouse model

PURPOSE

Using a diet-induced obesity (DIO) mouse model, we investigated the antidiabetic effect of Labrador tea [Rhododendron groenlandicum (Oeder) Kron and Judd], a beverage and medicinal tea used by the Cree Nations of northern Quebec.

METHODS

C57BL6 mice were divided into five groups and given standard chow (~4 % of lipids) or high-fat diet (~35 % of lipids) for 8 weeks until they became obese and insulin resistant. Treatment began by adding the plant extract at three doses (125, 250 and 500 mg/kg) to the high-fat diet for another 8 weeks. At the end of the study, insulin-sensitive tissues (liver, skeletal muscle, adipose tissue) were collected to investigate the plant's molecular mechanisms.

RESULTS

Labrador tea significantly reduced blood glucose (13 %), the response to an oral glucose tolerance test (18.2 %) and plasma insulin (65 %) while preventing hepatic steatosis (42 % reduction in hepatic triglyceride levels) in DIO mice. It stimulated insulin-dependent Akt pathway (55 %) and increased the expression of GLUT4 (53 %) in skeletal muscle. In the liver, Labrador tea stimulated the insulin-dependent Akt and the insulin-independent AMP-activated protein kinase pathways. The improvement in hepatic steatosis observed in DIO-treated mice was associated with a reduction in inflammation (through the IKK α/β) and a decrease in the hepatic content of SREBP-1 (39 %).

CONCLUSIONS

Labrador tea exerts potential antidiabetic action by improving insulin sensitivity and mitigating high-fat diet-induced obesity and hyperglycemia. They validate the safety and efficacy of this plant, a promising candidate for culturally relevant complementary treatment in Cree diabetics.

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.

Cortisol effects on flow-experience

RATIONALE

Stress affects flow-experience, but the mediating psychobiological mechanisms remain unknown. Previous studies showed an association between flow-experience and endogenous cortisol levels, suggesting an inverted, u-shaped relation between flow-experience and cortisol. However, these studies could not exclude effects of other stress factors.

OBJECTIVES

The aim of this experiment was, therefore, to test the isolated effect of cortisol on flow-experience, independent of concomitant physiological and psychological stress responses, via controlled administration of exogenous cortisol.

METHODS

Sixty-four young healthy subjects (32 males, 32 females) participated in the experiment. According to a double-blind, randomized, placebo-controlled, cross-over design, they received 20 mg oral cortisol on 1 day and placebo on the other day, respectively, with a time distance of 1 week between the experimental days. One hour after cortisol administration, participants engaged in the computer game Pacman. Pacman was delivered in five blocks of randomly differing difficulty levels. One block lasted 5 min. At the end of each block, participants rated flow-experience by the Flow Short Scale. Data was analyzed with hierarchical linear modeling. Subjects were not able to predict whether the pill they received contained cortisol or placebo.

RESULTS

Overall, results revealed a negative effect of oral 20 mg cortisol on flow-experience, with no differences between males and females.

CONCLUSIONS

This study is the first to show that exogenous cortisol in a dose corresponding to a severe stressor impairs flow-experience. The observed negative effect of high cortisol dosage on experienced flow underlines recent findings of an inverted u-shaped relationship between cortisol and flow.

Hormones as "difference makers" in cognitive and socioemotional aging processes

Aging is associated with well-recognized alterations in brain function, some of which are reflected in cognitive decline. While less appreciated, there is also considerable evidence of socioemotional changes later in life, some of which are beneficial. In this review, we examine age-related changes and individual differences in four neuroendocrine systems-cortisol, estrogen, testosterone, and oxytocin-as "difference makers" in these processes. This suite of interrelated hormonal systems actively coordinates regulatory processes in brain and behavior throughout development, and their level and function fluctuate during the aging process. Despite these facts, their specific impact in cognitive and socioemotional aging has received relatively limited study. It is known that chronically elevated levels of the stress hormone cortisol exert neurotoxic effects on the aging brain with negative impacts on cognition and socioemotional functioning. In contrast, the sex hormones estrogen and testosterone appear to have neuroprotective effects in cognitive aging, but may decrease prosociality. Higher levels of the neuropeptide oxytocin benefit socioemotional functioning, but little is known about the effects of oxytocin on cognition or about age-related changes in the oxytocin system. In this paper, we will review the role of these hormones in the context of cognitive and socioemotional aging. In particular, we address the aforementioned gap in the literature by: (1) examining both singular actions and interrelations of these four hormonal systems; (2) exploring their correlations and causal relationships with aspects of cognitive and socioemotional aging; and (3) considering multilevel internal and external influences on these hormone systems within the framework of explanatory pluralism. We conclude with a discussion of promising future research directions.

Acute stress and working memory in older people

Several studies have shown that acute stress affects working memory (WM) in young adults, but the effect in older people is understudied. As observed in other types of memory, older people may be less sensitive to acute effects of stress on WM. We performed two independent studies with healthy older men and women (from 55 to 77 years old) to investigate the effects of acute stress (Trier Social Stress Test; TSST) and cortisol on WM. In study 1 (n = 63), after the TSST women (but not men) improved their performance on Digit Span Forward (a measure of the memory span component of WM) but not on Digit Span Backward (a measure of both memory span and the executive component of WM). Furthermore, in women, cortisol levels at the moment of memory testing showed a positive association with the memory span component of WM before and after the TSST, and with the executive component of WM only before the stress task. In study 2 (n = 76), although participants showed a cortisol and salivary alpha-amylase (sAA) response to the TSST, stress did not affect performance on Letter-Number Sequencing (LNS; a task that places a high demand on the executive component of WM). Cortisol and sAA were not associated with WM. The results indicate that circulating cortisol levels at the moment of memory testing, and not the stress response, affect memory span in older women, and that stress and the increase in cortisol levels after stress do not affect the executive component of WM in older men and women. This study provides further evidence that older people may be less sensitive to stress and stress-induced cortisol response effects on memory processes.

Morning cortisol levels in schizophrenia and bipolar disorder: a meta-analysis

Increased peripheral levels of morning cortisol have been reported in people with schizophrenia (SZ) and bipolar disorder (BD), but findings are inconsistent and few studies have conducted direct comparisons of these disorders. We undertook a meta-analysis of studies examining single measures of morning cortisol (before 10 a.m.) levels in SZ or BD, compared to controls, and to each other; we also sought to examine likely moderators of any observed effects by clinical and demographic variables. Included studies were obtained via systematic searches conducted using Medline, BIOSIS Previews and Embase databases, as well as hand searching. The decision to include or exclude studies, data extraction and quality assessment was completed in duplicate by LG, SM and AS. The initial search revealed 1459 records. Subsequently, 914 were excluded on reading the abstract because they did not meet one or more of the inclusion criteria; of the remaining 545 studies screened in full, included studies were 44 comparing SZ with controls, 19 comparing BD with controls, and 7 studies directly comparing schizophrenia with bipolar disorder. Meta-analysis of SZ (N=2613, g=0.387, p=0.001) and BD (N=704, g=0.269, p=0.004) revealed moderate quality evidence of increased morning cortisol levels in each group compared to controls, but no difference between the two disorders (N=392, g=0.038, p=0.738). Subgroup analyses revealed greater effect sizes for schizophrenia samples with an established diagnosis (as opposed to 'first-episode'), those that were free of medication, and those sampled in an inpatient setting (perhaps reflecting an acute illness phase). In BD, greater morning cortisol levels were found in outpatient and non-manic participants (as opposed to those in a manic state), relative to controls. Neither age nor sex affected cortisol levels in any group. However, earlier greater increases in SZ morning cortisol were evident in samples taken before 8 a.m. (relative to those taken after 8 a.m.). Multiple meta-regression showed that medication status was significantly associated with morning cortisol levels in SZ, when the effects of assay method, sampling time and illness stage were held constant. Heightened levels of morning cortisol in SZ and BD suggest long-term pathology of the hypothalamic-pituitary-adrenal (HPA) axis that may reflect a shared process of illness development in line with current stress-vulnerability models.

Rapid cortisol enhancement of psychomotor and startle reactions to side-congruent stimuli in a focused cross-modal choice reaction time paradigm

The stress hormone cortisol has been shown to affect hemodynamic activity of human brain structures, presumably via a nongenomic mechanism. However, behavioral implications of this finding remain unknown. In a placebo-controlled, blinded, cross-over design the rapid effects of IV hydrocortisone (5mg) on cross-modal integration of simultaneous, unilateral visual and acoustic signals in a challenging startle and reaction time (RT) paradigm were studied. On two separate days 1 week apart, 24 male volunteers responded by button push to either up- or down pointing triangles presented in random sequence in the periphery of one of the visual hemi-fields. Visual targets were accompanied by unilateral acoustic startle noise bursts, presented at the same or opposite side. Saccadic latency, manual RT, and startle eye blink responses were recorded. Faster manual reactions and increased startle eye blink responses were observed 11-20 min after hydrocortisone administration when visual targets and unilateral acoustic startle noises were presented in the same sensory hemi-field, but not when presented in opposite sensory hemi-fields. Our results suggest that a nongenomic, cortisol-sensitive mechanism enhances psychomotor and startle reactions when stimuli occur in the same sensory hemi-field. Such basic cognitive effects of cortisol may serve rapid adaptation and protection against danger stimuli in stressful contexts.

Stress exposure prior to fear acquisition interacts with estradiol status to alter recall of fear extinction in humans

Classical fear acquisition and extinction are important models for the etiology and treatment of anxiety disorders such as posttraumatic stress disorder (PTSD). Women are at a higher risk for PTSD than men. Levels of circulating 17-β estradiol (E2) in women have been linked to deficits in fear extinction and extinction recall. In PTSD, fear learning coincides with acute traumatic stress. However, little is known about the possible interaction between stress exposure and hormone status on fear acquisition and extinction learning. In a 2-day, 2×3 between-subjects design with healthy participants, we examined the effects of stress (psychosocial stressor vs. control, placed 45 min prior to conditioning) and natural E2-status on differential fear conditioning, covering fear acquisition, immediate extinction (Day 1), and 24h-delayed extinction recall (Day 2). To operationalize E2-status, we compared women in the early follicular phase (EF) of their menstrual cycle (low E2, low progesterone plasma levels), women in the midcycle phase (MC, high E2, low progesterone), and men. Conditioning was indicated by differential skin conductance responses. We found an interaction between stress exposure and natural E2-status in women only: In MC-women, extinction recall on Day 2 (24h after initial extinction training) was better when fear acquisition had been preceded by stress. In EF-women, the inverse was true. We show that extinction recall of conditioned fear acquired after stress depends on estrogen status in women. Therefore, extinction-based exposure therapy in free-cycling female anxiety patients should take cycle status into account.

Cancer, coping, and cognition: a model for the role of stress reactivity in cancer-related cognitive decline

BACKGROUND

Cognitive decline and accompanying neurological changes associated with non-CNS cancer diagnosis and treatment have been increasingly identified in a subset of patients. Initially believed to be because of neurotoxic effects of chemotherapy exposure, observation of cognitive decline in patients not treated with chemotherapy, cancer-diagnosed individuals prior to treatment, and patients receiving alternative treatment modalities (surgery, endocrine therapy, and radiation) has led to the investigation of additional potential etiologies and moderating factors. Stressful experiences have long been posited as a contributor to these cognitive changes. Through reciprocal connectivity with peripheral systems, the brain maintains a dynamic circuitry to adapt to stress (allostasis). However, overuse of this system leads to dysregulation and contributes to pathophysiology (allostatic load). At this time, little research has been conducted to systematically examine the role of allostatic load in cancer-related cognitive dysfunction.

METHODS AND RESULTS

Here, we integrate theories of stress biology, neuropsychology, and coping and propose a model through which individuals with a high level of allostatic load at diagnosis may be particularly vulnerable to the neurocognitive effects of cancer.

CONCLUSIONS

Opportunities for future research to test and extend proposed mechanisms are discussed in addition to points of prevention and intervention based on individual variation in stress reactivity and coping skills.

Diazepam and fluoxetine decrease the stress response in zebrafish

The presence of pharmaceutical products in the aquatic environment has been reported in several studies. However, the impact of these drugs on living organisms is still uncharacterized. Here, we investigated the effects of acute exposure to either diazepam or fluoxetine on the stress response in Danio rerio. We showed that diazepam and fluoxetine inhibited the stress axis in zebrafish. Intermediate concentrations of diazepam suppressed the stress response as measured by cortisol levels, whereas fluoxetine inhibited cortisol increase at concentrations similar to those found in the environment. These data suggest that the presence of psychoactive drugs in aquatic ecosystems could cause neuroendocrine dysfunction in fish.

Cortisol awakening response and spatial working memory in man: a U-shaped relationship

OBJECTIVE

The association between hypothalamic-pituitary-adrenal (HPA)-axis function and cognition has long been investigated. An inverted U-shaped relationship has been described between various measures of HPA-axis function and neuropsychological performance in animals and man. Work with glucocorticoid receptor manipulation has corroborated these findings, with particular effects observed in relation to spatial working memory (SWM). As HPA-axis dysfunction is frequently found in patients with psychiatric illness, research in this area has potential implications for the treatment of the commonly observed cognitive impairment in such disorders. Here, we present the results of a pilot study examining the relationship between cortisol awakening response (CAR) and cognitive functions known to be susceptible to HPA-axis manipulation.

METHODS

Nineteen healthy male volunteers were recruited, and their CAR and performance in a task of SWM were assessed.

RESULTS

A highly significant quadratic relationship was observed between the CAR and SWM error rate (R(2)=0.63, p=0.001).

CONCLUSION

We provide novel evidence supporting the existence of an inverted U-shaped relationship between corticosteroid levels and cognitive function in humans.

Acute stress impairs the retrieval of extinction memory in humans

Extinction training is a form of inhibitory learning that allows an organism to associate a previously aversive cue with a new, safe outcome. Extinction does not erase a fear association, but instead creates a competing association that may or may not be retrieved when a cue is subsequently encountered. Characterizing the conditions under which extinction learning is expressed is important to enhancing the treatment of anxiety disorders that rely on extinction-based exposure therapy as a primary treatment technique. The ventromedial prefrontal cortex, which plays a critical role in the expression of extinction memory, has been shown to be functionally impaired after stress exposure. Further, recent work in rodents has demonstrated that exposure to stress leads to deficits in extinction retrieval, although this has yet to be tested in humans. To explore how stress might influence extinction retrieval in humans, participants underwent a differential aversive learning paradigm, in which one image was probabilistically paired with an aversive shock while the other image denoted safety. Extinction training directly followed, at which point reinforcement was omitted. A day later, participants returned to the lab and either completed an acute stress manipulation (i.e., cold pressor), or a control task, before undergoing an extinction retrieval test. Skin conductance responses and salivary cortisol concentrations were measured throughout each session as indices of fear arousal and neuroendocrine stress response, respectively. The efficacy of our stress induction was established by observing significant increases in cortisol for the stress condition only. We examined extinction retrieval by comparing conditioned responses during the last trial of extinction (day 1) with that of the first trial of re-extinction (day 2). Groups did not differ on initial fear acquisition or extinction, however, a day later participants in the stress group (n=27) demonstrated significantly lower extinction retrieval (i.e., greater fear recovery) than those in the control group (n=25). Our results suggest that acute stress impairs the retrieval of extinction learning and offers insight into why treatment strategies used in the clinic may be challenging to recruit in daily life where stress is pervasive.

Remembering under stress: different roles of autonomic arousal and glucocorticoids in memory retrieval

It is commonly assumed that stress impairs memory retrieval. Glucocorticoids, released with a delay of several minutes in response to stressful experiences, are thought to play a key role in the stress-induced retrieval impairment. Accordingly, most studies on the impact of stress on retrieval tested memory a considerable time after stressor exposure, when glucocorticoid levels were elevated. Here, we asked how stress affects memory when retrieval takes place under stress, that is, when stress is part of the retrieval situation and glucocorticoids are not yet increased at the time of testing. To contrast stress effects on ongoing and delayed memory retrieval, 72 participants learned first neutral and emotional material. Twenty-four hours later, half of the learned material was tested either in a stressful, oral examination-like testing situation or in a standard, non-stressful free recall test. Memory for the other half of the learned material was assessed 25 min after the first, stressful or non-stressful retention test. Significant increases in blood pressure and salivary cortisol confirmed the stress induction by the first, examination-like testing situation. Retrieval performance under stress was positively correlated with the blood pressure response to the stressor but unaffected by cortisol. Conversely, retrieval performance 25 min post stress was negatively correlated with the cortisol response to the stressor, particularly for emotional items. These results suggest that the same stressor may have opposite effects on ongoing and delayed memory retrieval, depending on the presence of autonomic arousal and glucocorticoids.

Academic self-concept of ability and cortisol reactivity

The present study aimed to clarify the relationship between a school-specific trait (academic self-concept of ability [ASCA]) and hormonal stress response by using a trait-compatible stressor (test). First, we determined 52 students' ASCA scores for biology and measured their salivary cortisol concentration before and after a biology test (experimental group, n=28) or a free writing task (control group, n=24). For participants who took the test, statistical analysis indicated a significant negative correlation between ASCA score and cortisol response. In contrast, the control group showed a decrease in cortisol concentrations between test times and no correlation between cortisol concentration and ASCA scores were found. These findings indicated an interaction between ASCA scores and hormonal stress response when an academic-related stressor is present. Furthermore, these variables might influence each other adversely: high cortisol concentrations during a test situation may lead to greater feelings of insecurity, resulting in low ASCA scores and awareness of these low scores may lead to a further increase in cortisol, creating a vicious cycle.

Cortisol rapidly affects amplitudes of heartbeat-evoked brain potentials--implications for the contribution of stress to an altered perception of physical sensations?

Little is known about the impact of stress and stress hormones on the processing of visceral-afferent signals. Clinical data suggest that cortisol may lower the threshold for interoceptive stimuli, while a pharmacological administration of cortisol decreases the sensitivity for physical symptoms. To clarify the role of cortisol for the processing of interoceptive signals, we investigated 16 healthy men on two occasions, once during the infusion of 4 mg of cortisol and once during the infusion of a placebo substance. Heartbeat-evoked potentials (HEP; derived from resting EEG and ECG, during open and closed eyes), which are psychophysiological indicators for the cortical processing of cardioceptive signals, were measured over 6-min periods once before, and four times after the infusion (1-7, 11-17, 21-27 and 31-37 min). We found that HEP amplitudes were higher during open than during closed eyes between 1 and 17 min after cortisol infusion. There was no effect of cortisol on heart rate. We conclude that cortisol may rapidly modulate the cortical processing of cardioceptive neural signals. These results may have relevance for the effects of stress on the development and maintenance of psychosomatic symptoms.

Stress and glucocorticoid receptor-dependent mechanisms in long-term memory: from adaptive responses to psychopathologies

A proper response against stressors is critical for survival. In mammals, the stress response is primarily mediated by secretion of glucocorticoids via the hypothalamic-pituitary-adrenocortical (HPA) axis and release of catecholamines through adrenergic neurotransmission. Activation of these pathways results in a quick physical response to the stress and, in adaptive conditions, mediates long-term changes in the brain that lead to the formation of long-term memories of the experience. These long-term memories are an essential adaptive mechanism that allows an animal to effectively face similar demands again. Indeed, a moderate stress level has a strong positive effect on memory and cognition, as a single arousing or moderately stressful event can be remembered for up to a lifetime. Conversely, exposure to extreme, traumatic, or chronic stress can have the opposite effect and cause memory loss, cognitive impairments, and stress-related psychopathologies such as anxiety disorders, depression and post-traumatic stress disorder (PTSD). While more effort has been devoted to the understanding of the negative effects of chronic stress, much less has been done thus far on the identification of the mechanisms engaged in the brain when stress promotes long-term memory formation. Understanding these mechanisms will provide critical information for use in ameliorating memory processes in both normal and pathological conditions. Here, we will review the role of glucocorticoids and glucocorticoid receptors (GRs) in memory formation and modulation. Furthermore, we will discuss recent findings on the molecular cascade of events underlying the effect of GR activation in adaptive levels of stress that leads to strong, long-lasting memories. Our recent data indicate that the positive effects of GR activation on memory consolidation critically engage the brain-derived neurotrophic factor (BDNF) pathway. We propose and will discuss the hypothesis that stress promotes the formation of strong long-term memories because the activation of hippocampal GRs after learning is coupled to the recruitment of the growth and pro-survival BDNF/cAMP response element-binding protein (CREB) pathway, which is well-know to be a general mechanism required for long-term memory formation. We will then speculate about how these results may explain the negative effects of traumatic or chronic stress on memory and cognitive functions.

Plasma cortisol in Alzheimer's disease with or without depressive symptoms

Background

Cortisol is presumed to be a risk factor for stress- and age-related disorders, such as depressive disorder and Alzheimer’s disease (AD). The aim of this study was to investigate the association of plasma cortisol concentration with AD in presence or absence of comorbid depressive symptoms.

Material/Methods

Plasma cortisol concentration was measured in 80 AD patients (35 of them with depressive symptoms), 27 elderly depressive patients without AD, and 37 elderly controls.

Results

Compared to controls, a significant increase of mean plasma cortisol was found in AD patients but not in depressive patients. Plasma cortisol was positively correlated with cognitive impairment in AD patients. We confirmed a U-shaped association between plasma cortisol and major depression and a linear association between plasma cortisol and AD without depressive symptoms. Significantly increased relative risk of disease in people with high plasma cortisol was found for AD with depressive symptoms and for AD with mild dementia.

Conclusions

Plasma cortisol reflects the degree of cognitive impairment in AD rather than the severity of comorbid depression. We confirmed that both hypercortisolemia and hypocortisolemia are associated with depressive disorder. Significant association between high plasma cortisol and AD was found, supporting the use of high plasma cortisol as a component of a panel of biochemical markers for AD with depressive symptoms as well as AD in the early stage of dementia development.