The effects of stress and stress hormones on human cognition: Implications for the field of brain and cognition

Corticosteroid effects on cellular physiology of limbic cells

After stress, circulating levels of stress hormones such as corticosterone are markedly increased. This will have an impact on the neurophysiology of limbic neurons that highly express corticosteroid receptors. Over the past decades several principles about the neurophysiological impact of corticosterone have emerged. First, corticosterone can quickly raise the excitability of hippocampal CA1 neurons shortly after stress exposure, via a nongenomic pathway involving mineralocorticoid receptors presumably located in the pre- as well as postsynaptic membrane. At the same time, gene-mediated actions via the glucocorticoid receptor are started which some hours later will result in enhanced calcium influx and impaired ability to induce long-term potentiation. These delayed actions are interpreted as a means to slowly normalize hippocampal activity and preserve information encoded early on after stress. Second, the full spectrum of neurophysiological actions by corticosterone is accomplished in interaction with other stress mediators, like noradrenaline. Third, these effects in the CA1 hippocampal region cannot be generalized to other brain regions such as the basolateral amygdala or paraventricular nucleus: There seems to be a highly differentiated response, which could serve to facilitate neuroendocrine/cognitive processing of some aspects of stress-related information, but attenuate other aspects. Finally, the time- and region-specific corticosteroid actions strongly depend on the individual's life history.

Long working hours and cognitive function: the Whitehall II Study

This study examined the association between long working hours and cognitive function in middle age. Data were collected in 1997-1999 (baseline) and 2002-2004 (follow-up) from a prospective study of 2,214 British civil servants who were in full-time employment at baseline and had data on cognitive tests and covariates. A battery of cognitive tests (short-term memory, Alice Heim 4-I, Mill Hill vocabulary, phonemic fluency, and semantic fluency) were measured at baseline and at follow-up. Compared with working 40 hours per week at most, working more than 55 hours per week was associated with lower scores in the vocabulary test at both baseline and follow-up. Long working hours also predicted decline in performance on the reasoning test (Alice Heim 4-I). Similar results were obtained by using working hours as a continuous variable; the associations between working hours and cognitive function were robust to adjustments for several potential confounding factors including age, sex, marital status, education, occupation, income, physical diseases, psychosocial factors, sleep disturbances, and health risk behaviors. This study shows that long working hours may have a negative effect on cognitive performance in middle age.

Early postnatal weight gain, intellectual performance, and body mass index at 7 years of age in term infants with intrauterine growth restriction

OBJECTIVE

To determine whether the postnatal growth rate of infants with intrauterine growth restriction (IUGR) is associated with later cognitive function and body mass index (BMI).

STUDY DESIGN

Infants with IUGR (<2211 g at > or =37 weeks' gestation) were identified in data from the Collaborative Perinatal Project, excluding those with diagnoses affecting cognition or growth. Wechsler Scale of Children's Intelligence (WISC) scores at age 7 years and data on postnatal growth at 16 weeks were available for 463 infants with IUGR. Linear regression relating postnatal growth and WISC score, adjusting for potential confounders, was performed for these infants. BMI at 7 years also was examined.

RESULTS

Weight gain at 16 postnatal weeks ranged from 1059 to 5119 g in the infants with IUGR, with lower achieved cognitive testing scores apparent at both extremes (ie, an inverted J-shape; P < .001). Infants gaining 1200 and 5000 g scored 15.5 and 2.4 fewer points, respectively, on the full scale compared with infants with score-maximizing growth. In contrast, BMI at 7 years was linearly related to postnatal weight gain (P < .001).

CONCLUSIONS

Growth in the first 4 postnatal months is an independent risk factor for cognitive outcome at age 7 years, with both extremes associated with negative effects.

Stress effects on working memory, explicit memory, and implicit memory for neutral and emotional stimuli in healthy men

Stress is a strong modulator of memory function. However, memory is not a unitary process and stress seems to exert different effects depending on the memory type under study. Here, we explored the impact of social stress on different aspects of human memory, including tests for explicit memory and working memory (for neutral materials), as well as implicit memory (perceptual priming, contextual priming and classical conditioning for emotional stimuli). A total of 35 young adult male students were randomly assigned to either the stress or the control group, with stress being induced by the Trier Social Stress Test (TSST). Salivary cortisol levels were assessed repeatedly throughout the experiment to validate stress effects. The results support previous evidence indicating complex effects of stress on different types of memory: A pronounced working memory deficit was associated with exposure to stress. No performance differences between groups of stressed and unstressed subjects were observed in verbal explicit memory (but note that learning and recall took place within 1 h and immediately following stress) or in implicit memory for neutral stimuli. Stress enhanced classical conditioning for negative but not positive stimuli. In addition, stress improved spatial explicit memory. These results reinforce the view that acute stress can be highly disruptive for working memory processing. They provide new evidence for the facilitating effects of stress on implicit memory for negative emotional materials. Our findings are discussed with respect to their potential relevance for psychiatric disorders, such as post traumatic stress disorder.

Mechanisms regulating the susceptibility of hematopoietic malignancies to glucocorticoid-induced apoptosis

Glucocorticoids (GCs) are commonly used in the treatment of hematopoietic malignancies owing to their ability to induce apoptosis of these cancerous cells. Whereas some types of lymphoma and leukemia respond well to this drug, others are resistant. Also, GC-resistance gradually develops upon repeated treatments ultimately leading to refractory relapsed disease. Understanding the mechanisms regulating GC-induced apoptosis is therefore uttermost important for designing novel treatment strategies that overcome GC-resistance. This review discusses updated data describing the complex regulation of the cell's susceptibility to apoptosis triggered by GCs. We address both the genomic and nongenomic effects involved in promoting the apoptotic signals as well as the resistance mechanisms opposing these signals. Eventually we address potential strategies of clinical relevance that sensitize GC-resistant lymphoma and leukemia cells to this drug. The major target is the nongenomic signal transduction machinery where the interplay between protein kinases determines the cell fate. Shifting the balance of the kinome towards a state where Glycogen synthase kinase 3alpha (GSK3alpha) is kept active, favors an apoptotic response. Accumulating data show that it is possible to therapeutically modulate GC-resistance in patients, thereby improving the response to GC therapy.

Bringing the bedside to the bench, and then to the community: a prospectus for intervention research in late-life anxiety disorders

BACKGROUND

Anxiety disorders are highly prevalent in elderly persons, and they are associated with functional impairment, poorer quality of life, and adverse long-term consequences such as cognitive decline. Intervention research in late-life anxiety disorders (LLAD) lags behind where it ought to be. Research in cognitive neuroscience, aging, and stress intersects in LLAD and provides the opportunity to develop innovative interventions to prevent chronic anxiety and its consequences in this age group.

METHODS

This paper evaluates gaps in the evidence base for treatment of LLAD and synthesizes recent research in cognitive neuroscience, basic behavioral science, stress, and aging.

RESULTS

We examine three intervention issues in LLAD: (1) prevention; (2) acute treatment; and (3) pre-empting adverse consequences. We propose combining randomized controlled trials (RCTs) with mechanistic biobehavioral methodologies as an optimal approach for developing novel, optimized, and personalized treatments. Additionally, we examine three barriers in the field of LLAD research: (1) How do we measure anxiety?; (2) How do we raise awareness?; (3) How will we ensure our research is applicable to underserved populations (particularly minority groups)?

CONCLUSIONS

This prospectus outlines approaches for intervention research that can reduce the morbidity of LLAD.

Morning cortisol Levels in preschool-aged foster children: differential effects of maltreatment type

Maltreated foster children are subjected to a range of early adverse experiences, including neglect, abuse, and multiple caregiver disruptions. Research suggests that such disturbances alter the development and subsequent functioning of the hypothalamic-pituitary-adrenocortical system. The current study was designed to investigate morning cortisol levels in 117 foster children and 60 low-income, nonmaltreated children. Maltreatment and foster care placement experiences were coded from official records. Analyses revealed that the foster children were significantly more likely than the nonmaltreated children to have low morning cortisol levels. Additionally, specific maltreatment experiences were significantly associated with the foster children's morning cortisol levels. Foster children with low morning cortisol levels experienced more severe physical neglect than the other foster children. In contrast, foster children with high morning cortisol levels experienced more severe emotional maltreatment. These results suggest that specific early adverse experiences have differential effects on the functioning of the hypothalamic-pituitary-adrenocortical system.

Pathways linking late-life depression to persistent cognitive impairment and dementia

There is a strong association between late-life depression, cognitive impairment, cerebrovascular disease, and poor cognitive outcomes, including progressive dementia, especially Alzheimer's disease. While neuroimaging evidence suggests that cerebrovascular disease plays a prominent role, it seems that depression alone may also confer substantial risk for developing Alzheimer's disease. The relationships between the prominent cerebrovascular changes, other structural abnormalities, specific forms of cognitive dysfunction, and increased risk for developing Alzheimer's disease among those with late-life depression have been difficult to reconcile. The varied findings suggest that there are likely multiple pathways to poor cognitive outcomes. We present a framework outlining multiple, non-mutually exclusive etiologic links between depression, cognitive impairment, and progressive decline, including dementia. Importantly, the model is both testable and falsifiable. Going forward, using models such as this to inform research should accelerate knowledge acquisition on the depression/dementia relationship that may be useful for dementia prevention, monitoring the impact of depression treatment on clinical status and course of illness.

Stress impairs acquisition of delay eyeblink conditioning in men and women

In rodents stress impairs delay as well as trace eyelid conditioning in females, but enhances it in males. The present study tested the effects of acute psychosocial stress exposure on classical delay eyeblink conditioning in healthy men and women. In a between subject design, participants were exposed to psychosocial stress using the Trier Social Stress Test (TSST) or a control condition which was followed by a delay eyeblink classical conditioning procedure. Stress exposure led to a significant increase in salivary cortisol and impaired acquisition of conditioned eyeblink responses (CRs). This was evident by a later first CR and an overall lower CR rate of the stress group. The stress-induced acquisition impairment was observed in both women and men. Subjects failing to show a stress-induced cortisol increase (cortisol non-responder) were not impaired in acquisition. Our findings indicate that acute stress, possibly via activation of the hypothalamus-pituitary-adrenal (HPA) axis, reduces the ability to acquire a simple conditioned motor response in humans.

Increased cortisol levels in cognitively challenging situations are beneficial in young but not older subjects

RATIONALE

Adaptation to stressful situations changes with increasing age. This is also reflected in age-related differences in effects of acute stress on, e.g., episodic memory. Less is known about age-related differences of the cognitive effects of individual stress responses to challenging situations.

OBJECTIVE

To investigate the influence of the individual cortisol response (as a marker for the individual stress level) on behavioral and neural measures during a challenging memory paradigm.

MATERIALS AND METHODS

Twenty young and 12 older subjects were scanned using functional magnetic resonance imaging during encoding and retrieval of spatial contextual information. Salivary cortisol levels were measured before and after scanning.

RESULTS

A multiple regression analysis of behavioral data showed an interaction effect of age and cortisol response on memory for the items and their spatial context during retrieval due to increased accuracy with increasing cortisol responses in young compared to old subjects. During encoding, this was reflected in a positive effect of the cortisol response on prefrontal activity in young but not in older subjects. During retrieval, there was a negative effect of the cortisol response on brain activity in the hippocampus and prefrontal regions in older but not in young subjects.

CONCLUSIONS

The data suggest an increased efficiency to encode items and their context with increasing cortisol responses in young subjects, and a decreased efficiency to retrieve information with increasing cortisol responses in older subjects. We conclude that neuroendocrine responses are differentially associated with behavioral and neural measures in cognitively challenging situations in young and older volunteers.

Emanuel Miller Lecture: early onset depressions--meanings, mechanisms and processes

BACKGROUND

Depressive syndromes in children and adolescents constitute a serious group of mental disorders with considerable risk for recurrence. A more precise understanding of aetiology is necessary to improve treatment and management.

METHODS

Three neuroactive agents are purported to be involved in the aetiology of these disorders: serotonin, brain-derived neurotrophic factor and cortisol. A literature review was conducted to determine their contributions to the emergence of unipolar depressions in the adolescent years.

RESULTS

Serotonin, brain-derived neurotrophic factor and cortisol may operate in concert within two distinct functional frameworks: atypical early epigenesis arising in the first few years of life and resulting in the formation of a vulnerable neuronal network involving in particular the amygdala and ventral prefrontal cortex. Individuals with this vulnerability are likely to show impaired mood regulation when faced with environmental demands during adolescence and over the subsequent decades; and acquired neuroendangerment, a pathological brain process leading to reduced synaptic plasticity, in particular in the hippocampus and perhaps the nucleus accumbens and ventral tegmentum. This may result in motivational, cognitive and behavioural deficits at any point in the lifespan most apparent at times of environmental demand.

CONCLUSIONS

The characteristics, course and outcome of a depressive episode may depend on the extent of the involvement of both atypical early neurogenesis and acquired neuroendangerment.

Linear and non-linear dose-response functions reveal a hormetic relationship between stress and learning

Over a century of behavioral research has shown that stress can enhance or impair learning and memory. In the present review, we have explored the complex effects of stress on cognition and propose that they are characterized by linear and non-linear dose-response functions, which together reveal a hormetic relationship between stress and learning. We suggest that stress initially enhances hippocampal function, resulting from amygdala-induced excitation of hippocampal synaptic plasticity, as well as the excitatory effects of several neuromodulators, including corticosteroids, norepinephrine, corticotropin-releasing hormone, acetylcholine and dopamine. We propose that this rapid activation of the amygdala-hippocampus brain memory system results in a linear dose-response relation between emotional strength and memory formation. More prolonged stress, however, leads to an inhibition of hippocampal function, which can be attributed to compensatory cellular responses that protect hippocampal neurons from excitotoxicity. This inhibition of hippocampal functioning in response to prolonged stress is potentially relevant to the well-described curvilinear dose-response relationship between arousal and memory. Our emphasis on the temporal features of stress-brain interactions addresses how stress can activate, as well as impair, hippocampal functioning to produce a hormetic relationship between stress and learning.

Chronic stress during paradoxical sleep deprivation increases paradoxical sleep rebound: association with prolactin plasma levels and brain serotonin content

Previous studies suggest that stress associated to sleep deprivation methods can affect the expression of sleep rebound. In order to examine this association and possible mechanisms, rats were exposed to footshock stress during or immediately after a 96-h period of paradoxical sleep deprivation (PSD) and their sleep and heart rate were recorded. Control rats (maintained in individual home cages) and paradoxical sleep-deprived (PS-deprived) rats were distributed in three conditions (1) no footshock--NF; (2) single footshock--SFS: one single footshock session at the end of the PSD period (6-8 shocks per minute; 100 ms; 2 mA; for 40 min); and (3) multiple footshock--MFS: footshock sessions with the same characteristics as described above, twice a day throughout PSD (at 7:00 h and 19:00 h) and one extra session before the recovery period. After PSD, animals were allowed to sleep freely for 72 h. Additional groups were sacrificed at the end of the sleep deprivation period for blood sampling (ACTH, corticosterone, prolactin and catecholamine levels) and brain harvesting (monoamines and metabolites). Neither SFS nor MFS produced significant alterations in the sleep patterns of control rats. All PS-deprived groups exhibited increased heart rate which could be explained by increased dopaminergic activity in the medulla. As expected, PS deprivation induced rebound of paradoxical sleep in the first day of recovery; however, PSD+MFS group showed the highest rebound (327.3% above the baseline). This group also showed intermediate levels of corticosterone and the highest levels of prolactin, which were positively correlated with the length of PS episodes. Moreover, paradoxical sleep deprivation resulted in elevation of the serotonergic turnover in the hypothalamus, which partly explained the hormonal results, and in the hippocampus, which appears to be related to adaptive responses to stress. The data are discussed in the realm of a prospective importance of paradoxical sleep for processing of traumatic events.

Stress, health and ageing: a focus on postmenopausal women

Stress influences health and disease and this might be of special relevance for ageing. The present review starts with the description of age-associated changes of the hypothalamic-pituitary-adrenal axis. In this context, the possible modulatory role of estradiol is discussed. Later, the influence of rising stress hormone levels for the ageing brain is illustrated and a few intervention strategies are outlined. At the end, the concept of allostatic load (AL) is described, which aims at a broader assessment of the impact of stress on the individual. The strengths and also the current limitations of the AL concept are highlighted.

Adaptations in endocannabinoid signaling in response to repeated homotypic stress: a novel mechanism for stress habituation

Daily life stressors are a major environmental factor contributing to precipitation and exacerbation of mental illness. Animal models using repeated homotypic stress induce anxious and depressive phenotypes and are used to study the pathophysiology of affective disorders. Here we discuss data demonstrating that repeated homotypic stress produces temporally and anatomically distinct changes in endocannabinoid signaling components within stress-responsive brain regions. We also present evidence describing the neural and behavioral correlates of these adaptations in endocannabinoid signaling. These data support a role for endocannabinoid signaling in the central nervous system response to chronic, homotypic stress, and specifically in the process of stress-response habituation. The clinical implications of these findings for the pathophysiology and treatment of affective disorders are discussed.

Psychosocial stress induces working memory impairments in an n-back paradigm

In contrast to the substantial number of studies investigating the effects of stress on declarative memory, effects of stress on working memory have received less attention. We compared working memory (numerical n-back task with single digits) in 40 men exposed either to psychosocial stress (Trier Social Stress Test (TSST)) or a control condition. Task difficulty was varied using two conditions (2-back vs. 3-back). Salivary cortisol (as a marker of hypothalamus-pituitary-adrenal (HPA) activity) and salivary alpha-amylase (sAA as a marker of sympathetic nervous system (SNS) activity) were assessed immediately before and three times after the stress or control condition. As expected stress resulted in an increase in cortisol, sAA, and negative affect. Subjects exposed to stress showed significant working memory impairments in both workload conditions. The analysis of variance indicated a main effect of stress for reaction time as well as accuracy. In addition, for reaction time a stress-block interaction occurred. Follow up tests revealed that only during the first block at each level of difficulty performance was significantly impaired by stress. Thus, the effects of stress became smaller the longer the task was performed. Results provide further evidence for impaired working memory after acute stress and illustrate the time course of this phenomenon.

Neuroticism moderates the daily relation between stressors and memory failures

The present investigation extends previous work on the relationship between daily stressors and memory failures in a naturalistic setting by examining whether this relationship varies across levels of neuroticism. A daily diary study of 333 older adults (mean age = 73.27 years, SD = 7.17) in the Veterans Affairs Normative Aging Study (see A. Spiro & R. Bossé, 2001, for additional information) was used to examine whether there were neuroticism differences in cognitive reactivity to daily stressors. Multilevel models indicated that on days when people high in neuroticism experienced stressors, particularly interpersonal stressors, they were more likely to report memory failures compared to those who were lower in neuroticism. The findings may have important implications for age-related cognitive decline.

Steroid abnormalities and the developing brain: declarative memory for emotionally arousing and neutral material in children with congenital adrenal hyperplasia

Steroid hormones modulate memory in animals and human adults. Little is known on the developmental effects of these hormones on the neural networks underlying memory. Using Congenital adrenal hyperplasia (CAH) as a naturalistic model of early steroid abnormalities, this study examines the consequences of CAH on memory and its neural correlates for emotionally arousing and neutral material in children. Seventeen patients with CAH and 17 age- and sex-matched healthy children (ages 12-14 years) completed the study. Subjects were presented positive, negative and neutral pictures. Memory recall occurred about 30min after viewing the pictures. Children with CAH showed memory deficits for negative pictures compared to healthy children (p<0.01). There were no group differences on memory performance for either positive or neutral pictures (p>0.1). In patients, 24h urinary-free cortisol levels (reflecting glucocorticoid replacement therapy) and testosterone levels were not associated with memory performance. These findings suggest that early steroid imbalances affect memory for negative material in children with CAH. Such memory impairments may result from abnormal brain organization and function following hormonal dysfunction during critical periods of development.

Functional actions of corticosteroids in the hippocampus

Corticosteroid hormones are released in high amounts after stress. The hormones enter the brain compartment and bind to high affinity mineralocorticoid receptors--particularly enriched in limbic regions--as well as to lower affinity glucocorticoid receptors which are more ubiquitous. Shortly after the stressful event, corticosteroids (in concert with specific monoamines and neuropeptides) have the potential to increase cellular excitability in subfields of the hippocampus, like the CA1 area. These effects are rapid in onset and occur via a nongenomic pathway. At the same time, however, the hormones also start slower, gene-mediated processes. These cause attenuation of excitatory information flow through the CA1 hippocampal area. Induction of long-term potentiation at that time is impaired. This may help to normalize hippocampal activity some hours after the stressful event and preserve information encoded within the context of the event. These adaptational effects of the hormones may become maladaptive if the stressful event is associated with other challenges of the network (like ischemic insults) or when stress occurs repetitively, in an uncontrollable and unpredictable manner. In that case, i) normalization of activity seems to be less efficient (particularly when other limbic areas like the amygdala nuclei are activated during stress), ii) induction of long-term potentiation is hampered at all times and iii) serotonin responses are attenuated. This may contribute to the precipitation of clinical symptoms in stress-related disorders such as major depression. A better understanding of the corticosteroid actions could lead to a more rational treatment strategy of stress-related disorders.

Biological processes in prevention and intervention: the promotion of self-regulation as a means of preventing school failure

This paper examines interrelations between biological and social influences on the development of self-regulation in young children and considers implications of these interrelations for the promotion of self-regulation and positive adaptation to school. Emotional development and processes of emotion regulation are seen as influencing and being influenced by the development of executive cognitive functions, including working memory, inhibitory control, and mental flexibility important for the effortful regulation of attention and behavior. Developing self-regulation is further understood to reflect an emerging balance between processes of emotional arousal and cognitive regulation. Early childhood educational programs that effectively link emotional and motivational arousal with activities designed to exercise and promote executive functions can be effective in enhancing self-regulation, school readiness, and school success.

Effect of cortisol levels on working memory performance in elderly subjects with Alzheimer's disease

BACKGROUND: Subjects with Alzheimer's disease (AD) have elevated cortisol levels as a result of hypothalamic-pituitary-adrenal (HPA) axis dysfunction. Acute administration of hydrocortisone has been associated with working memory (WM) performance in young adults. OBJECTIVE: To investigate whether cortisol levels are associated with WM performance in subjects with AD. METHOD: Eighty subjects were included, comprising 40 patients with mild AD and 40 healthy elderly controls. WM was assessed using the Digit Span Backward test (DSB). Saliva samples were collected to determine cortisol levels. RESULTS: AD subjects had poorer performance on the DSB than controls (p=0.002) and also presented higher levels of cortisol than control group (p=0.04). No significant correlation was observed between the DSB and cortisol levels in both groups (r= -0.29). CONCLUSION: In this study, elevated cortisol levels were not associated with poorer WM performance in patients with AD or in healthy elderly subjects.

Neuroinflammation associated with aging sensitizes the brain to the effects of infection or stress

The aging brain is characterized by a shift from the homeostatic balance of inflammatory mediators to a proinflammatory state. This increase in neuroinflammation is marked by increased numbers of activated and primed microglia, increased steady-state levels of inflammatory cytokines and decreases in anti-inflammatory molecules. These conditions sensitize the aged brain to produce an exaggerated response to the presence of an immune stimulus in the periphery or following exposure to a stressor. In the brain, proinflammatory cytokines can have profound effects on behavioral and neural processes. As the aged brain is primed to respond to inflammatory stimuli, infection or stress may produce more severe detriments in cognitive function in the aged. Typically after an immune stimulus, aged animals display prolonged sickness behaviors, increased cytokine induction and greater cognitive impairments compared to adults. Additionally, aging can also augment the central response to stressors leading to exaggerated cytokine induction and increased decrements in learning and memory. This alteration in neuroinflammation and resultant sensitization to extrinsic and intrinsic stressors can have considerable effects upon the elderly's recovery and coping during disease and stress.

Polymorphism of the 5-HT(2A) receptor gene: association with stress-related indices in healthy middle-aged adults

Past research has concentrated on the stress system and personality in order to explain the variance found in cognitive performance in old age. A growing body of research is starting to focus on genetic polymorphism as an individual difference factor to explain the observed heterogeneity in cognitive function. While the functional mechanism is still under investigation, polymorphism of the 5-HT(2A) receptor gene (-1438A/G) has been linked to certain behavioral and physiological outcomes, including cortisol secretion, the expression of certain personality traits, and memory performance. It was the goal of the present study to investigate the association between the -1438A/G polymorphism and stress hormone secretion, stress-related psychological measures, and cognitive performance in a group of adults between the ages of 50 and 65. To examine these associations, 101 middle-aged adults were recruited, completed a battery of psychological questionnaires and were administered a battery of cognitive tasks that assess frontal lobe and hippocampal function. Basal and stress-reactive salivary cortisol levels were collected, at home and in the laboratory. Analyses on psychological measures showed that participants with the GG genotype reported significantly higher levels of neuroticism compared to the AG group and higher levels of depression and more emotion-based coping strategies compared to both the AG and AA group. In terms of cortisol secretion, the AA genotype was related to a significantly higher awakening cortisol response (ACR) compared to the AG and GG group and the GG genotype group displayed a greater increase in cortisol secretion following a psychosocial stressor compared to the two other groups. On measures of cognitive performance, the AA genotype group performed significantly better on a test of declarative memory and selective attention compared to the other two groups. Together, these results suggest that carriers of the GG genotype are more susceptible to low mood and display a greater potential for an overactive stress system, which may influence cognitive function in later years.