Stress and cardiovascular disease. Nat Rev Cardiol. 2012;9:360-370. [PMID: 22473079 DOI: 10.1038/nrcardio.2012.45]

Brain Physiology and Pathophysiology in Mental Stress

Exposure to various forms of stress is a common daily occurrence in the lives of most individuals, with both positive and negative effects on brain function. The impact of stress is strongly influenced by the type and duration of the stressor. In its acute form, stress may be a necessary adaptive mechanism for survival and with only transient changes within the brain. However, severe and/or prolonged stress causes overactivation and dysregulation of the hypothalamic pituitary adrenal (HPA) axis thus inflicting detrimental changes in the brain structure and function. Therefore, chronic stress is often considered a negative modulator of the cognitive functions including the learning and memory processes. Exposure to long-lasting stress diminishes health and increases vulnerability to mental disorders. In addition, stress exacerbates functional changes associated with various brain disorders including Alzheimer’s disease and Parkinson’s disease. The primary purpose of this paper is to provide an overview for neuroscientists who are seeking a concise account of the effects of stress on learning and memory and associated signal transduction mechanisms. This review discusses chronic mental stress and its detrimental effects on various aspects of brain functions including learning and memory, synaptic plasticity, and cognition-related signaling enabled via key signal transduction molecules.

Relationship of depression, stress and endothelial function in stable angina patients

Endothelial dysfunction has been considered as one of potential mechanisms by which depression and stress might contribute to the development of coronary artery disease (CAD). Recent studies suggest that circulating endothelial progenitor cells (EPCs) and brachial artery flow-mediated dilation (FMD) are related to endothelial function and progression of CAD. We investigated the relationships between the level of circulating CD34/KDR(+) EPCs and CD133/KDR(+) EPCs, brachial FMD, and scores of depression and stress measured with the Depression Anxiety Stress Scales in 288 stable angina patients without major psychiatric disorders. As defined by the ≥75th percentile, 100 (35%) subjects had high depression score (≥8), and 84 (29%) subjects had high stress score (≥10). Subjects with high depression or stress score had significantly lower FMD (1.86±0.14 vs. 3.63±0.17%, p<0.001; 2.05±0.18 vs. 3.48±0.17%, p<0.001) and percentage of circulating CD34/KDR(+) EPCs (0.97±0.11 vs. 1.94±0.17%, p<0.001; 1.09±0.13 vs. 1.68±0.16%, p=0.005), but not CD133/KDR(+) EPCs (0.52±0.04 vs. 0.66±0.06%, p=0.057; 0.61±0.05 vs. 0.59±0.05%, p=0.833), as compared with subjects with normal depression or stress score. Multivariate regression analysis indicated that high depression score (OR 1.09, 95% CI: 1.04-1.15, p<0.001), but not stress score or percentage of circulating EPCs, independently predicted impaired brachial FMD. In conclusions, our results demonstrated that in stable angina patients without major psychiatric disorders, a high depression or stress score was related to attenuated brachial FMD and depletion of circulating EPCs. However, only the depression score, but not the stress score or the level of EPCs, was an independent predictor for decreased brachial FMD.

Perceived organizational justice as a predictor of long-term sickness absence due to diagnosed mental disorders: results from the prospective longitudinal Finnish Public Sector Study

Organizational justice perceptions have been suggested to be associated with symptoms of mental health but the nature of the association is unknown due to reporting bias (measurement error related to response style and reversed causality). In this study, we used prospective design and long-term (>9 days) sickness absence with psychiatric diagnosis as the outcome measure. Participants were 21,221 Finnish public sector employees (the participation rate at baseline in 2000-2002 68%), who responded to repeated surveys of procedural and interactional justice in 2000-2004 along with register data on sickness absence with a diagnosis of depression or anxiety disorders (822 cases). Results from logistic regression analyses showed that a one-unit increase in self-reported and work-unit level co-worker assessed interactional justice was associated with a 25-32% lower odds of sickness absence due to anxiety disorders. These associations were robust to adjustments for a variety of potential individual-level confounders including chronic disease (adjusted OR for self-reported interactional justice 0.77, 95% CI 0.65-0.91) and were replicated using co-worker assessed justice. Only weak evidence of reversed causality was found. The results suggest that low organizational justice is a risk factor for sickness absence due to anxiety disorders.

Associations of job strain and lifestyle risk factors with risk of coronary artery disease: a meta-analysis of individual participant data

BACKGROUND

It is unclear whether a healthy lifestyle mitigates the adverse effects of job strain on coronary artery disease. We examined the associations of job strain and lifestyle risk factors with the risk of coronary artery disease.

METHODS

We pooled individual-level data from 7 cohort studies comprising 102 128 men and women who were free of existing coronary artery disease at baseline (1985-2000). Questionnaires were used to measure job strain (yes v. no) and 4 lifestyle risk factors: current smoking, physical inactivity, heavy drinking and obesity. We grouped participants into 3 lifestyle categories: healthy (no lifestyle risk factors), moderately unhealthy (1 risk factor) and unhealthy (2-4 risk factors). The primary outcome was incident coronary artery disease (defined as first nonfatal myocardial infarction or cardiac-related death).

RESULTS

There were 1086 incident events in 743,948 person-years at risk during a mean follow-up of 7.3 years. The risk of coronary artery disease among people who had an unhealthy lifestyle compared with those who had a healthy lifestyle (hazard ratio [HR] 2.55, 95% confidence interval [CI] 2.18-2.98; population attributable risk 26.4%) was higher than the risk among participants who had job strain compared with those who had no job strain (HR 1.25, 95% CI 1.06-1.47; population attributable risk 3.8%). The 10-year incidence of coronary artery disease among participants with job strain and a healthy lifestyle (14.7 per 1000) was 53% lower than the incidence among those with job strain and an unhealthy lifestyle (31.2 per 1000).

INTERPRETATION

The risk of coronary artery disease was highest among participants who reported job strain and an unhealthy lifestyle; those with job strain and a healthy lifestyle had half the rate of disease. A healthy lifestyle may substantially reduce disease risk among people with job strain.

The corpulent phenotype-how the brain maximizes survival in stressful environments

The reactivity of the stress system may change during the life course. In many—but not all—humans the stress reactivity decreases, once the individual is chronically exposed to a stressful and unsafe environment (e.g., poverty, work with high demands, unhappy martial relationship). Such an adaptation is referred to as habituation. Stress habituation allows alleviating the burden of chronic stress, particularly cardiovascular morbidity and mortality. Interestingly, two recent experiments demonstrated low stress reactivity during a mental or psychosocial challenge in subjects with a high body mass. In this focused review we attempt to integrate these experimental findings in a larger context. Are these data compatible with data sets showing a prolonged life expectancy in corpulent people? From the perspective of neuroenergetics, we here raise the question whether “obesity” is unhealthy at all. Is the corpulent phenotype possibly the result of “adaptive phenotypic plasticity” allowing optimized survival in stressful environments?

Low socioeconomic status and psychological distress as synergistic predictors of mortality from stroke and coronary heart disease

BACKGROUND

The purpose of this study was to test whether lower socioeconomic status (SES) augments the effect of psychological distress on mortality from stroke or coronary heart disease (CHD).

METHODS

We prospectively linked data from 66,500 participants 35 years or older in the Health Survey for England, selected using stratified random sampling from 1994 to 2004, and free of cardiovascular disease and cancer at baseline, with mortality records. The median follow-up time was 7.9 years. SES was indexed by occupational class, and psychological distress was assessed using the 12-item General Health Questionnaire (GHQ-12).

RESULTS

After adjustment for demographic and clinical variables, both psychological distress and low SES were associated with increased mortality: the hazard ratios (HR) for one-category increase in low SES (three categories in total) were 1.15 for stroke-death (95% confidence interval [CI] = 1.00-1.31, p = .043) and 1.24 for CHD-death (95% CI = 1.09-1.41, p = .001); the HR for one-category increase in GHQ-12 (three categories in total) was 1.18 for stroke-death (95% CI = 1.07-1.30, p = .001) and 1.24 for CHD-death (95% CI = 1.13-1.36, p < .001). In stratified analyses, the strongest associations were found in the lowest SES categories: the HR for GHQ-12 toward stroke-death was 1.15 in high-SES participants (95% CI = 0.97-1.37, p = .107) and 1.31 in low-SES ones (95% CI = 1.13-1.51, p < .001); the HR for GHQ-12 toward CHD-death was 1.10 in high-SES participants (95% CI = 0.97-1.25, p = .129) and 1.33 in low-SES ones (95% CI = 1.19-1.48, p < .001).

CONCLUSIONS

People in low socioeconomic circumstances are more vulnerable to the adverse effect of psychological distress. This pattern should be taken into account when evaluating the association between psychosocial variables and health outcomes.

Working conditions in mid-life and mental health in older ages

This article illustrates the importance of previous working conditions during mid-life (between 40 and 55) for mental health among older retired men and women (60 or older) across 13 European countries. We link information on health from the second wave (2006-2007) of the Survey of Health, Ageing and Retirement in Europe (SHARE) with information on respondents' working life collected retrospectively in the SHARELIFE interview (2008-2009). To measure working conditions, we rely on core assumptions of existing theoretical models of work stress (the demand-control-support and the effort-reward imbalance model) and distinguish four types of unhealthy working conditions: (1) a stressful psychosocial work environment (as assessed by the two work stress models) (2) a disadvantaged occupational position throughout the whole period of mid-life, (3) experience of involuntary job loss, and (4) exposure to job instability. Health after labour market exit is measured using depressive symptoms, as measured by the EURO-D depression scale. Main results show that men and women who experienced psychosocial stress at work or had low occupational positions during mid-life had significantly higher probabilities of high depressive symptoms during retirement. Additionally, men with unstable working careers and an involuntary job loss were at higher risks to report high depressive symptoms in later life. These associations remain significant after controlling for workers' health and social position prior mid-life. These findings support the assumption that mental health of retirees who experienced poor working conditions during mid-life is impaired.

Vessels of Stone: Lenin's "circulatory disturbance of the brain"

Many have wondered what might have become of the totalitarian state Lenin founded on merciless terror, had he not died so young. He was 52 and at the height of his power when he had his first stroke. Six months later he had another and then a third stroke three months after that. He died 3 months shy of his 54th birthday with cerebral arteries so calcified that when tapped with tweezers at the time of his autopsy, they sounded like stone. The reason for his premature atherosclerosis has yet to be explained. He had a family history of cardiovascular disease and, therefore, is suspected of having had an inherited lipid disorder. Stress too might have had a role in the progression of his atherosclerosis. However, neither would explain the extent of the calcification of his cerebral arteries identified at post mortem examination. A recently described variant of the NT5E mutation might explain such calcification, as well as Lenin's family history of cardiovascular disease, and his premature cerebrovascular attacks.

Stress and cardiovascular disease: an update on current knowledge

Considerable progress has been made during the past decade in research on cardiovascular effects of stress. Early-life stressors, such as childhood abuse and early socioeconomic adversity, are linked to increased cardiovascular morbidity in adulthood. Our updated meta-analyses of prospective studies published until 2011 show a 1.5-fold (95% confidence interval 1.2-1.9) increased risk of coronary heart disease among adults experiencing social isolation and a 1.3-fold (1.2-1.5) excess risk for workplace stress; adverse metabolic changes are one of the underlying plausible mechanisms. Stress, anger, and depressed mood can act as acute triggers of major cardiac events; the pooled relative risk of acute coronary syndrome onset being preceded by stress is 2.5 (1.8-3.5) in case-crossover studies. Stress is also implicated in the prognosis of cardiovascular disease and in the development of stress (takotsubo) cardiomyopathy. A major challenge over the next decade is to incorporate stress processes into the mainstream of cardiovascular pathophysiological research and understanding.

Effort-reward-imbalance in healthy teachers is associated with higher LPS-stimulated production and lower glucocorticoid sensitivity of interleukin-6 in vitro

BACKGROUND

According to the effort-reward-imbalance (ERI) model, a lack of reciprocity between costs and gains at work increases the risk for adverse health outcomes. Inflammation has been shown to play a crucial role in a variety of stress-related diseases and alterations in immune system glucocorticoid sensitivity may help to explain the increased risk for cardiovascular disease (CVD) and depression related to chronic work stress.

METHODS

Changes in lipopolysaccharide (LPS)-induced interleukin (IL)-6 production and inhibition of IL-6 production by dexamethasone in reaction to the Trier Social Stress Test (TSST) were assessed in forty-six healthy school teachers to test whether chronic work stress is accompanied by alterations in inflammatory activity and glucocorticoid sensitivity of the innate immune system.

RESULTS

High ERI was associated with an increase in pro-inflammatory potential, reflected in elevated IL-6 production before and after stress and with a lower capacity of dexamethasone to suppress IL-6 production in vitro over all measurement time points. ERI was not associated with stress-related changes in GC sensitivity.

CONCLUSION

The present findings suggest a less effective anti-inflammatory regulation by glucocorticoids in teachers suffering from chronic work stress.

Psychosocial stress and cardiovascular disease risk: the role of physical activity

Chronic stress and depression are associated with increased risk of cardiovascular disease and poorer prognosis, and physical (in)activity may be a key underlying biobehavioral mechanism. Physical activity has antidepressant effects, and physically fitter, more active individuals seem to be more biologically resilient to psychosocial stressors. This article will present data from a series of population cohort studies and laboratory-based psychophysiological studies to explore the role of physical activity as a protective factor against the effects of psychosocial stress on cardiovascular disease. These mechanisms may improve the treatment and prevention of stress-related illnesses and, thus, has important implications for public health and clinical care of high-risk patients.

Job strain as a risk factor for coronary heart disease: a collaborative meta-analysis of individual participant data

BACKGROUND

Published work assessing psychosocial stress (job strain) as a risk factor for coronary heart disease is inconsistent and subject to publication bias and reverse causation bias. We analysed the relation between job strain and coronary heart disease with a meta-analysis of published and unpublished studies.

METHODS

We used individual records from 13 European cohort studies (1985-2006) of men and women without coronary heart disease who were employed at time of baseline assessment. We measured job strain with questions from validated job-content and demand-control questionnaires. We extracted data in two stages such that acquisition and harmonisation of job strain measure and covariables occurred before linkage to records for coronary heart disease. We defined incident coronary heart disease as the first non-fatal myocardial infarction or coronary death.

FINDINGS

30,214 (15%) of 197,473 participants reported job strain. In 1·49 million person-years at risk (mean follow-up 7·5 years [SD 1·7]), we recorded 2358 events of incident coronary heart disease. After adjustment for sex and age, the hazard ratio for job strain versus no job strain was 1·23 (95% CI 1·10-1·37). This effect estimate was higher in published (1·43, 1·15-1·77) than unpublished (1·16, 1·02-1·32) studies. Hazard ratios were likewise raised in analyses addressing reverse causality by exclusion of events of coronary heart disease that occurred in the first 3 years (1·31, 1·15-1·48) and 5 years (1·30, 1·13-1·50) of follow-up. We noted an association between job strain and coronary heart disease for sex, age groups, socioeconomic strata, and region, and after adjustments for socioeconomic status, and lifestyle and conventional risk factors. The population attributable risk for job strain was 3·4%.

INTERPRETATION

Our findings suggest that prevention of workplace stress might decrease disease incidence; however, this strategy would have a much smaller effect than would tackling of standard risk factors, such as smoking.

FUNDING

Finnish Work Environment Fund, the Academy of Finland, the Swedish Research Council for Working Life and Social Research, the German Social Accident Insurance, the Danish National Research Centre for the Working Environment, the BUPA Foundation, the Ministry of Social Affairs and Employment, the Medical Research Council, the Wellcome Trust, and the US National Institutes of Health.

Depressive symptoms and psychosocial stress at work among older employees in three continents

Background

To assess whether an association of psychosocial stress at work with depressive symptoms among older employees is evident in a set of comparable empirical studies from Europe, North America and Asia.

Methods

Cross-sectional and longitudinal multivariate regression analyses of data from 4 cohort studies with elder workers (2004 and 2006) testing associations of psychosocial stress at work (‘effort-reward imbalance’; ‘low control’) with depressive symptoms.

Results

Cross-sectional analyses from 17 countries with 14.236 participants reveal elevated odds ratios of depressive symptoms among people experiencing high work stress compared to those with low or no work stress. Adjusted odds ratios vary from 1.64 (95% CI 1.02-2.63) in Japan to 1.97 (95% CI 1.75-2.23) in Europe and 2.28 (95% CI 1.59-3.28) in the USA. Odds ratios from additional longitudinal analyses (in 13 countries) controlling for baseline depression are smaller, but remain in part significant.

Conclusion

Findings indicate that psychosocial stress at work might be a relevant risk factor for depressive symptoms among older employees across countries and continents. This observation may call for global policy efforts to improve quality of work in view of a rapidly aging workforce, in particular in times of economic globalization.

Copy number variation in the mouse genome: implications for the mouse as a model organism for human disease

Individuals within a species have genetic differences which ultimately result in the spectrum of phenotypic variation that we observe. Genetic variation exists at the nucleotide level in the form of single nucleotide polymorphisms (SNPs), and at a structural level as inversions, deletions and amplifications of larger stretches of nucleotides. Profiling of human and mouse genomes has identified numerous genomic segmental copy number variations (CNVs) throughout these genomes. Since inbred mice are widely used laboratory models for the study of both normal and disease biology, it is crucial that we understand the full scope of genetic variation, including CNVs, within these animals. These genetic differences can inform us about the history of a population or species, enlighten us on gene function, and guide our selection of a model system for the study of human disease.