Dynamics of telomerase activity in response to acute psychological stress

Telomerase activity plays an essential role in cell survival, by lengthening telomeres and promoting cell growth and longevity. It is now possible to quantify the low levels of telomerase activity in human leukocytes. Low basal telomerase activity has been related to chronic stress in people and to chronic glucocorticoid exposure in vitro. Here we test whether leukocyte telomerase activity changes under acute psychological stress. We exposed 44 elderly women, including 22 high stress dementia caregivers and 22 matched low stress controls, to a brief laboratory psychological stressor, while examining changes in telomerase activity of peripheral blood mononuclear cells (PBMCs). At baseline, caregivers had lower telomerase activity levels than controls, but during stress telomerase activity increased similarly in both groups. Across the entire sample, subsequent telomerase activity increased by 18% one hour after the end of the stressor (p<0.01). The increase in telomerase activity was independent of changes in numbers or percentages of monocytes, lymphocytes, and specific T cell types, although we cannot fully rule out some potential contribution from immune cell redistribution in the change in telomerase activity. Telomerase activity increases were associated with greater cortisol increases in response to the stressor. Lastly, psychological response to the tasks (greater threat perception) was also related to greater telomerase activity increases in controls. These findings uncover novel relationships of dynamic telomerase activity with exposure to an acute stressor, and with two classic aspects of the stress response - perceived psychological stress and neuroendocrine (cortisol) responses to the stressor.

Depression gets old fast: do stress and depression accelerate cell aging?

Depression has been likened to a state of "accelerated aging," and depressed individuals have a higher incidence of various diseases of aging, such as cardiovascular and cerebrovascular diseases, metabolic syndrome, and dementia. Chronic exposure to certain interlinked biochemical pathways that mediate stress-related depression may contribute to "accelerated aging," cell damage, and certain comorbid medical illnesses. Biochemical mediators explored in this theoretical review include the hypothalamic-pituitary-adrenal axis (e.g., hyper- or hypoactivation of glucocorticoid receptors), neurosteroids, such as dehydroepiandrosterone and allopregnanolone, brain-derived neurotrophic factor, excitotoxicity, oxidative and inflammatory stress, and disturbances of the telomere/telomerase maintenance system. A better appreciation of the role of these mediators in depressive illness could lead to refined models of depression, to a re-conceptualization of depression as a whole body disease rather than just a "mental illness," and to the rational development of new classes of medications to treat depression and its related medical comorbidities.

Association of marine omega-3 fatty acid levels with telomeric aging in patients with coronary heart disease

CONTEXT

Increased dietary intake of marine omega-3 fatty acids is associated with prolonged survival in patients with coronary heart disease. However, the mechanisms underlying this protective effect are poorly understood.

OBJECTIVE

To investigate the association of omega-3 fatty acid blood levels with temporal changes in telomere length, an emerging marker of biological age.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study of 608 ambulatory outpatients in California with stable coronary artery disease recruited from the Heart and Soul Study between September 2000 and December 2002 and followed up to January 2009 (median, 6.0 years; range, 5.0-8.1 years).

MAIN OUTCOME MEASURES

We measured leukocyte telomere length at baseline and again after 5 years of follow-up. Multivariable linear and logistic regression models were used to investigate the association of baseline levels of omega-3 fatty acids (docosahexaenoic acid [DHA] and eicosapentaenoic acid [EPA]) with subsequent change in telomere length.

RESULTS

Individuals in the lowest quartile of DHA+EPA experienced the fastest rate of telomere shortening (0.13 telomere-to-single-copy gene ratio [T/S] units over 5 years; 95% confidence interval [CI], 0.09-0.17), whereas those in the highest quartile experienced the slowest rate of telomere shortening (0.05 T/S units over 5 years; 95% CI, 0.02-0.08; P < .001 for linear trend across quartiles). Levels of DHA+EPA were associated with less telomere shortening before (unadjusted beta coefficient x 10(-3) = 0.06; 95% CI, 0.02-0.10) and after (adjusted beta coefficient x 10(-3) = 0.05; 95% CI, 0.01-0.08) sequential adjustment for established risk factors and potential confounders. Each 1-SD increase in DHA+EPA levels was associated with a 32% reduction in the odds of telomere shortening (adjusted odds ratio, 0.68; 95% CI, 0.47-0.98).

CONCLUSION

Among this cohort of patients with coronary artery disease, there was an inverse relationship between baseline blood levels of marine omega-3 fatty acids and the rate of telomere shortening over 5 years.

Black sheep get the blues: a psychobiological model of social rejection and depression

Major life events involving social rejection are strongly associated with onset of depression. To account for this relation, we propose a psychobiological model in which rejection-related stressors elicit a distinct and integrated set of cognitive, emotional, and biological changes that may evoke depression. In this model, social rejection events activate brain regions involved in processing negative affect and rejection-related distress (e.g., anterior insula, dorsal anterior cingulate cortex). They also elicit negative self-referential cognitions (e.g., "I'm undesirable," "Other people don't like me") and related self-conscious emotions (e.g., shame, humiliation). Downstream biological consequences include upregulation of the hypothalamic-pituitary-adrenal axis, sympathetic-adrenal-medullary axis, and inflammatory response. Pro-inflammatory cytokines play an important role in this process because they induce a constellation of depressotypic behaviors called sickness behaviors. Although these changes can be short-lived, sustained inflammation may occur via glucocorticoid resistance, catecholamines, sympathetic innervation of immune organs, and immune cell aging. This response also may be moderated by several factors, including prior life stress, prior depression, and genes implicated in stress reactivity.

Glucocorticoids. Mood, memory, and mechanisms

Elevated circulating levels of glucocorticoids are associated with psychiatric symptoms across several different conditions. It remains unknown if this hormonal abnormality is a cause or an effect of the psychiatric conditions. For example, the hypercortisolemia observed in a subset of patients with depression may have a direct impact on the symptoms of depression, but it is also possible that the hypercortisolemia merely reflects the stress associated with depression. Further, rather than causing depression, hypercortisolemia could represent a homeostatic attempt to overcome glucocorticoid resistance. Each of these possibilities will be considered, and correlational and causal evidence will be reviewed. This article will focus on the relationships between glucocorticoids and psychiatric symptoms in Cushing's syndrome, major depression, and steroid psychosis/steroid dementia, as well as the effects of exogenously administered glucocorticoids in normal volunteers. Similarities and differences in the relationship of glucocorticoid hormones to psychiatric symptoms in these conditions will be reviewed. Possible mediators of glucocorticoid effects on the brain and behavior, as well as possible "pro-aging" effects of glucocorticoids in certain cells of the body, will be reviewed. The article concludes with a conceptual model of glucocorticoid actions in the brain that may lead to novel therapeutic opportunities.

Pessimism correlates with leukocyte telomere shortness and elevated interleukin-6 in post-menopausal women

The combination of less positive and more negative expectations for the future (i.e., lower optimism and higher pessimism) increases risk for disease and early mortality. We tested the possibility that expectancies might influence health outcomes by altering the rate of biological aging, specifically of the immune system (immunosenescence). However, no studies to date have examined associations between optimism or pessimism and indicators of immunosenescence such as leukocyte telomere length (TL) and interleukin-6 (IL-6) levels. We investigated whether dispositional tendencies towards optimism and pessimism were associated with TL and IL-6 in a sample of 36 healthy post-menopausal women. Multiple regression analyses where optimism and pessimism were entered simultaneously, and chronological age and caregiver status were controlled, indicated that pessimism was independently associated with shorter TL (beta=-.68, p=.001) and higher IL-6 concentrations (beta=.50, p=.02). In contrast, optimism was not independently associated with either measure of immunosenescence. These findings suggest that dispositional pessimism may increase IL-6 and accelerate rate of telomere shortening. Mechanistic causal relationships between these parameters need to be investigated.

Telomeres in a Life-Span Perspective

In order to more fully understand associations between psychological stress and health, it is helpful for researchers to identify “psychobiomarkers,” or biological measures that are regulated in part by psychological function and that predict longevity. Telomere length appears to be such a measure. Telomeres, the protective caps at the tips of chromosomes, shorten with age, and this shortening predicts disease and longevity. Leukocyte telomere length may be best viewed through a life-span approach, as it reflects in part the cumulative number of cell divisions that have occurred and the long-term biochemical environment. Recently, a critical mass of studies demonstrated that telomeres appear to shorten with chronic stress, although the mechanisms are unknown. This paper reviews what appear to be malleable determinants of rate of telomere attrition, focusing on early life chronic stressors and metabolic adversity (poor nutrition during development, and obesity). The next generation of research will benefit from experimental and longitudinal models integrating genetic variation, social environments, life experience, and health behaviors.

Psychological and metabolic stress: a recipe for accelerated cellular aging?

Chronic stress can affect human health through a myriad of behavioral and biochemical pathways. Tauhis review focuses on some key hormonal and metabolic pathways that appear important today. In modern society, we are faced with excessive psychological stress, as well as an epidemic of overeating, and the two together appear to have synergistic effects. Chronic stress can lead to overeating, co-elevation of cortisol and insulin, and suppression of certain anabolic hormones. This state of metabolic stress in turn promotes abdominal adiposity. Both the direct stress response and the accumulation of visceral fat can promote a milieu of systemic inflammation and oxidative stress. This biochemical environment appears to be conducive to several cell aging mechanisms, mainly dampening telomerase and leading to telomere length (TL) shortening and cell senescence. Immune cell telomere shortness is linked with many chronic disease states and earlier mortality. In this way, chronic stress may influence a variety of diseases through a biochemical cascade leading to immune cell senescence. Certain psychological temperaments at high risk of this stress cascade (mainly anxiety prone), gene-environment interactions, and potential interventions for interrupting the stress-aging cascade are discussed.

Neurobiological and neuropsychiatric effects of dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEAS)

DHEA and DHEAS are steroids synthesized in human adrenals, but their function is unclear. In addition to adrenal synthesis, evidence also indicates that DHEA and DHEAS are synthesized in the brain, further suggesting a role of these hormones in brain function and development. Despite intensifying research into the biology of DHEA and DHEAS, many questions concerning their mechanisms of action and their potential involvement in neuropsychiatric illnesses remain unanswered. We review and distill the preclinical and clinical data on DHEA and DHEAS, focusing on (i) biological actions and putative mechanisms of action, (ii) differences in endogenous circulating concentrations in normal subjects and patients with neuropsychiatric diseases, and (iii) the therapeutic potential of DHEA in treating these conditions. Biological actions of DHEA and DHEAS include neuroprotection, neurite growth, and antagonistic effects on oxidants and glucocorticoids. Accumulating data suggest abnormal DHEA and/or DHEAS concentrations in several neuropsychiatric conditions. The evidence that DHEA and DHEAS may be fruitful targets for pharmacotherapy in some conditions is reviewed.

The rate of leukocyte telomere shortening predicts mortality from cardiovascular disease in elderly men

Telomere length (TL) has been proposed as a marker of mitotic cell age and as a general index of human organismic aging. Short absolute leukocyte telomere length has been linked to cardiovascular-related morbidity and mortality. Our aim was to test whether the rate of change in leukocyte TL is related to mortality in a healthy elderly cohort. We examined a subsample of 236 randomly selected Caucasian participants from the MacArthur Health Aging Study (aged 70 to 79 years). DNA samples from baseline and 2.5 years later were assayed for mean TL of leukocytes. Percent change in TL was calculated as a measure of TL change (TLC). Associations between TL and TLC with 12-year overall and cardiovascular mortality were assessed. Over the 2.5 year period, 46% of the study participants showed maintenance of mean bulk TL, whereas 30% showed telomere shortening, and, unexpectedly, 24% showed telomere lengthening. For women, short baseline TL was related to greater mortality from cardiovascular disease (OR = 2.3; 95% CI: 1.0 - 5.3). For men, TLC (specifically shortening), but not baseline TL, was related to greater cardiovascular mortality, OR = 3.0 (95% CI: 1.1 - 8.2). This is the first demonstration that rate of telomere length change (TLC) predicts mortality and thus may be a useful prognostic factor for longevity.

Positive affect uniquely predicts lower risk of mortality in people with diabetes

OBJECTIVE

To determine whether positive affect predicts mortality among people with diabetes and among a comparison group of people with no chronic health conditions.

DESIGN

Longitudinal cohort study.

MAIN OUTCOME MEASURE

Mortality.

RESULTS

Positive affect was significantly associated with lower risk of all-cause mortality in people with diabetes (N = 715). Enjoyed life was associated with lower risk of mortality over and above the effects of negative affect or other significant predictors of mortality. In a comparison sample without chronic illness (N = 2,673), positive affect was not associated with mortality. However, when the analysis was restricted to those over the age of 65, specific positive affects, in particular hopeful and enjoyed life were significantly associated with lower risk of mortality, again independent of negative affect. Enjoyed life remained significantly predictive of lower risk of mortality in the older sample when other predictors of mortality were statistically controlled. Positive affect was particularly protective among those over the age of 65 who reported higher levels of stress.

CONCLUSION

These findings are discussed in light of possible stress-buffering functions of positive affect.

Why egalitarianism might be good for your health: physiological thriving during stressful intergroup encounters

We compared how evaluations by out-group members and evaluations by in-group members affected participants' stress responses--their neuroendocrine reactivity, cognitive appraisals, and observed anxiety--and how participants' implicit racial bias moderated these responses. Specifically, White participants completed measures of racial bias prior to the experiment. During the experiment, participants performed speech and serial subtraction tasks in front of White or Black interviewers. Several saliva samples were obtained, and they were assayed for catabolic ("breaking down") and anabolic ("building up") hormones. Interviewers' race and participants' racial bias interacted in predicting stress responses. When interviewers were Black, lower racial bias was linked with more salutary stress responses: lower threat appraisals, less anxiety, and increased levels of anabolic hormones. When interviewers were White, no effect was found for threat appraisals or anabolic hormones, and the reverse effect was observed for anxiety. Egalitarianism may have physical and psychological benefits for people living in a diverse society.

Stress, eating and the reward system

An increasing number of people report concerns about the amount of stress in their life. At the same time obesity is an escalating health problem worldwide. Evidence is accumulating rapidly that stress related chronic stimulation of the hypothalamic-pituitary-adrenal (HPA) axis and resulting excess glucocorticoid exposure may play a potential role in the development of visceral obesity. Since adequate regulation of energy and food intake under stress is important for survival, it is not surprising that the HPA axis is not only the 'conductor' of an appropriate stress response, but is also tightly intertwined with the endocrine regulation of appetite. Here we attempt to link animal and human literatures to tease apart how different types of psychological stress affect eating. We propose a theoretical model of Reward Based Stress Eating. This model emphasizes the role of cortisol and reward circuitry on motivating calorically dense food intake, and elucidating potential neuroendocrine mediators in the relationship between stress and eating. The addiction literature suggests that the brain reward circuitry may be a key player in stress-induced food intake. Stress as well as palatable food can stimulate endogenous opioid release. In turn, opioid release appears to be part of an organisms' powerful defense mechanism protecting from the detrimental effects of stress by decreasing activity of the HPA axis and thus attenuating the stress response. Repeated stimulation of the reward pathways through either stress induced HPA stimulation, intake of highly palatable food or both, may lead to neurobiological adaptations that promote the compulsive nature of overeating. Cortisol may influence the reward value of food via neuroendocrine/peptide mediators such as leptin, insulin and neuropeptide Y (NPY). Whereas glucocorticoids are antagonized by insulin and leptin acutely, under chronic stress, that finely balanced system is dysregulated, possibly contributing to increased food intake and visceral fat accumulation. While these mechanisms are only starting to be elucidated in humans, it appears the obesity epidemic may be exacerbated by the preponderance of chronic stress, unsuccessful attempts at food restriction, and their independent and possibly synergistic effects on increasing the reward value of highly palatable food.

Cell aging in relation to stress arousal and cardiovascular disease risk factors

We previously reported that psychological stress is linked to and possibly accelerates cellular aging, as reflected by lower PBMC telomerase and shortened telomeres. Psychological stress is a major risk factor for cardiovascular disease (CVD), with multiple behavioral and physiological mediators. Telomere shortness has been associated with CVD, but the relationship between low telomerase activity, a potential precursor to telomere shortening, and CVD risk factors has not been examined in humans. Here we examine whether telomere length and telomerase in leukocytes are associated with physiological signs of stress arousal and CVD risk factors in 62 healthy women. Low telomerase activity in leukocytes was associated with exaggerated autonomic reactivity to acute mental stress and elevated nocturnal epinephrine. Further, low telomerase activity was associated with the major risk factors for CVD -smoking, poor lipid profile, high systolic blood pressure, high fasting glucose, greater abdominal adiposity-as well as to a composite Metabolic Syndrome variable. Telomere length was related only to elevated stress hormones (catecholamines and cortisol). Thus, we propose that low leukocyte telomerase constitutes an early marker of CVD risk, possibly preceding shortened telomeres, that results in part from chronic stress arousal. Possible cellular mechanisms by which low telomerase may link stress and traditional risk factors to CVD are discussed. These findings may implicate telomerase as a novel and important mediator of the effects of psychological stress on physical health and disease.

Accelerated telomere shortening in response to life stress

Numerous studies demonstrate links between chronic stress and indices of poor health, including risk factors for cardiovascular disease and poorer immune function. Nevertheless, the exact mechanisms of how stress gets "under the skin" remain elusive. We investigated the hypothesis that stress impacts health by modulating the rate of cellular aging. Here we provide evidence that psychological stress--both perceived stress and chronicity of stress--is significantly associated with higher oxidative stress, lower telomerase activity, and shorter telomere length, which are known determinants of cell senescence and longevity, in peripheral blood mononuclear cells from healthy premenopausal women. Women with the highest levels of perceived stress have telomeres shorter on average by the equivalent of at least one decade of additional aging compared to low stress women. These findings have implications for understanding how, at the cellular level, stress may promote earlier onset of age-related diseases.

Flattened cortisol rhythms in metastatic breast cancer patients

Allostatic load, the physiological accumulation of the effects of chronic stressors, has been associated with multiple adverse health outcomes. Flattened diurnal cortisol rhythmicity is one of the prototypes of allostatic load, and has been shown to predict shorter survival among women with metastatic breast cancer. The current study compared diurnal cortisol slope in 17 breast cancer patients and 31 controls, and tested associations with variables previously found to be related to cortisol regulation, i.e, abdominal adiposity, perceived stress, social support, and explicit memory. Women with metastatic breast cancer had significantly flatter diurnal cortisol rhythms than did healthy controls. Patients with greater disease severity showed higher mean cortisol levels, smaller waist circumference, and a tendency toward flatter diurnal cortisol rhythms. There were no relations between cortisol slope and psychological or cognitive functioning among patients. In contrast, controls with flatter rhythms showed the expected allostatic load profile of larger waist circumference, poorer performance on explicit memory tasks, lower perceived social support, and a tendency toward higher perceived stress. These findings suggest that the cortisol diurnal slope may have important but different correlates in healthy women versus those with breast cancer.

Sex differences in stress responses: social rejection versus achievement stress

BACKGROUND

Sex differences in stress responses may be one mechanism underlying gender differences in depression. We hypothesized that men and women would show different adrenocortical responses to different stressors. In particular, we predicted that women would show greater responses to social rejection stressors, whereas men would demonstrate greater responses to achievement stressors.

METHODS

Following a rest session in which they habituated to the laboratory, 50 healthy volunteers (24 men and 26 women, mean age 19.1, SD = 1.13) were randomly assigned to achievement or rejection stress conditions. The achievement condition involved a mathematical and a verbal challenge; the rejection condition involved two social interaction challenges. Self-reported affect and salivary cortisol were measured throughout each stress session (baseline, stress, and poststress periods).

RESULTS

There were no sex differences in mood ratings following the stressors; however, cortisol responses showed the predicted gender by condition by time interaction. Men showed significantly greater cortisol responses to the achievement challenges, but women showed greater cortisol responses to the social rejection challenges.

CONCLUSIONS

Women appear more physiologically reactive to social rejection challenges, but men react more to achievement challenges. Women's greater reactivity to rejection stress may contribute to the increased rates of affective disorders in women.

Stress hormone-related psychopathology: pathophysiological and treatment implications

Stress is commonly associated with a variety of psychiatric conditions, including major depression, and with chronic medical conditions, including diabetes and insulin resistance. Whether stress causes these conditions is uncertain, but plausible mechanisms exist by which such effects might occur. To the extent stress-induced hormonal alterations (e.g., chronically elevated cortisol levels and lowered dehydroepiandrosterone [DHEA] levels) contribute to psychiatric and medical disease states, manipulations that normalize these hormonal aberrations should prove therapeutic. In this review, we discuss mechanisms by which hormonal imbalance (discussed in the frameworks of "allostatic load" and "anabolic balance") might contribute to illness. We then review certain clinical manifestations of such hormonal imbalances and discuss pharmacological and behavioural treatment strategies aimed at normalizing hormonal output and lessening psychiatric and physical pathology.

Relationship of subjective and objective social status with psychological and physiological functioning: preliminary data in healthy white women

This preliminary study compared the associations between objective and subjective socioeconomic status (SES) with psychological and physical variables among 157 healthy White women, 59 of whom subsequently participated in a laboratory stress study. Compared with objective indicators, subjective social status was more consistently and strongly related to psychological functioning and health-related factors (self-rated health, heart rate, sleep latency, body fat distribution, and cortisol habituation to repeated stress). Most associations remained significant even after controlling for objective social status and negative affectivity. Results suggest that, in this sample with a moderately restricted range on SES and health, psychological perceptions of social status may be contributing to the SES-health gradient.

Relationship of subjective and objective social status with psychological and physiological functioning: preliminary data in healthy white women

This preliminary study compared the associations between objective and subjective socioeconomic status (SES) with psychological and physical variables among 157 healthy White women, 59 of whom subsequently participated in a laboratory stress study. Compared with objective indicators, subjective social status was more consistently and strongly related to psychological functioning and health-related factors (self-rated health, heart rate, sleep latency, body fat distribution, and cortisol habituation to repeated stress). Most associations remained significant even after controlling for objective social status and negative affectivity. Results suggest that, in this sample with a moderately restricted range on SES and health, psychological perceptions of social status may be contributing to the SES-health gradient.

Stress and body shape: stress-induced cortisol secretion is consistently greater among women with central fat

OBJECTIVE

Excessive central fat puts one at greater risk of disease. In animal studies, stress-induced cortisol secretion has been shown to increase central fat. The objective of this study was to assess whether women with central fat distribution (as indicated by a high waist-to-hip ratio [WHR]), across a range of body mass indexes, display consistently heightened cortisol reactivity to repeated laboratory stressors.

METHODS

Fifty-nine healthy premenopausal women, 30 with a high WHR and 29 with a low WHR, were exposed to consecutive laboratory sessions over 4 days (three stress sessions and one rest session). During these sessions, cortisol and psychological responses were assessed.

RESULTS

Women with a high WHR evaluated the laboratory challenges as more threatening, performed more poorly on them, and reported more chronic stress. These women secreted significantly more cortisol during the first stress session than women with a low WHR. Furthermore, lean women with a high WHR lacked habituation to stress in that they continued to secrete significantly more cortisol in response to now familiar challenges (days 2 and 3) than lean women with a low WHR.

CONCLUSIONS

Central fat distribution is related to greater psychological vulnerability to stress and cortisol reactivity. This may be especially true among lean women, who did not habituate to repeated stress. The current cross-sectional findings support the hypothesis that stress-induced cortisol secretion may contribute to central fat and demonstrate a link between psychological stress and risk for disease.