Cardiovascular reactivity and the course of immune response to an acute psychological stressor

Impact of Federal, State, and Local Housing Policies on Disparities in Cardiovascular Disease in Black/African American Men and Women: From Policy to Pathways to Biology

Racist and discriminatory federal, state, and local housing policies significantly contribute to disparities in cardiovascular disease incidence and mortality for individuals that self-identify as Black or African American. Here we highlight three key housing policies - "redlining," zoning, and the construction of highways - which have wrought a powerful, sustained, and destructive impact on cardiovascular health in Black/African American communities. Redlining and highway construction policies have restricted access to quality health care, increased exposure to carcinogens such as PM_2.5, and increased exposure to extreme heat. At the root of these policy decisions are longstanding, toxic societal factors including racism, segregation, and discrimination, which also serve to perpetuate racial inequities in cardiovascular health. Here, we review these societal and structural factors and then link them with biological processes such as telomere shortening, allostatic load, oxidative stress, and tissue inflammation. Lastly, we focus on the impact of inflammation on the immune system and the molecular mechanisms by which the inflamed immune microenvironment promotes the formation of atherosclerotic plaques. We propose that racial residential segregation and discrimination increases tissue inflammation and cytokine production, resulting in dysregulated immune signaling, which promotes plaque formation and cardiovascular disease. This framework has the power to link structural racism not only to cardiovascular disease, but also to cancer.

Immune cell dynamics in response to an acute laboratory stressor: a within-person between-group analysis of the biological impact of early life adversity

Early life adversity (ELA) is a risk factor for early onset morbidities and mortality, a relationship that may be driven in part by immune system dysregulation. One mechanism of dysregulation that has yet to be fully examined in the context of ELA is alterations to immune cell dynamics in response to acute stress. Using a within-person between-group experimental design, we investigated stress-induced changes in immune cell populations, and how these changes may be altered in individuals with a history of ELA. Participants were young adults (N = 34, aged 18-25 years, 53% female, 47% with a history of ELA). Complete immune cell counts were measured at four time-points over a 5-hour window across two sessions (Trier Social Stress Test [TSST] vs. no-stress) separated by a week. Across all participants, total white blood cells increased over time (F(3,84)=38.97, p < .001) with a greater increase in response to the TSST compared to the no-stress condition at 240 minutes post-test (b = 0.43±.19; t(179)=2.22, p = .027). This pattern was mirrored by neutrophil counts. Lymphocyte counts were initially depressed by TSST exposure (b =-205±.67; t(184)=-3.07, p = .002) but recovered above baseline. ELA status was associated with higher stress-induced immune cell counts, a difference likely driven by increases in neutrophils (F(1,22)=4.45, p = .046). Overall, these results indicate differential immune cell dynamics in response to acute stress in individuals with a history of ELA. This points to altered immune system functioning in the context of stress, a finding that may be driving increased morbidity and mortality risk for ELA-exposed individuals.

What moderates salivary markers of inflammation reactivity to stress? A descriptive report and meta-regression

As the assessment of salivary markers of inflammation gains popularity in stress research, understanding factors that influence these markers' reactivity to stress is important. A recent meta-analysis synthesized literature on changes in salivary markers of inflammation in response to acute stressors in adults. As a supplement to this, we present pre-registered moderator analyses of salivary markers of inflammation responses to acute stress. Analyses included data from 27 studies (35 unique study samples). Outcomes were Cohen's d effect sizes for salivary biomarkers interleukin-1 beta (IL-1β), IL-6, IL-10, and tumor necrosis factor-alpha (TNF-α), from pre- to post-stress. Moderators included: college education levels of the study sample; percent of the study sample that identified as African-American; body mass index (BMI); use of a resting baseline saliva sample; and use of a social evaluative stressor. Descriptive results on saliva sample timing were also examined. Biomarkers peaked 0-60 minutes after the end of the stressor. Before removing influential outliers, no moderators of salivary inflammation reactivity emerged, though not all moderators could be tested due to missing data. After removing one influential outlier study, higher study sample average BMI was associated with greater salivary IL-1β reactivity to stress (b = 0.41, p=.007). For every 1-unit increase in study sample average BMI, effect sizes for IL-1β increased by 0.41 units. These findings suggest BMI may be important to examine when assessing salivary markers of inflammation in response to stress. As this field expands, it is important to replicate these results and consider the role of other moderators of salivary markers of inflammation reactivity to stress.

Environmental risk factors and cardiovascular diseases: a comprehensive review

Noncommunicable diseases (NCDs) are fatal for more than 38 million people each year and are thus the main contributors to the global burden of disease accounting for 70% of mortality. The majority of these deaths are caused by cardiovascular disease. The risk of NCDs is strongly associated with exposure to environmental stressors such as pollutants in the air, noise exposure, artificial light at night and climate change, including heat extremes, desert storms and wildfires. In addition to the traditional risk factors for cardiovascular disease such as diabetes, arterial hypertension, smoking, hypercholesterolemia and genetic predisposition, there is a growing body of evidence showing that physicochemical factors in the environment contribute significantly to the high NCD numbers. Furthermore, urbanization is associated with accumulation and intensification of these stressors. This comprehensive expert review will summarize the epidemiology and pathophysiology of environmental stressors with a focus on cardiovascular NCDs. We will also discuss solutions and mitigation measures to lower the impact of environmental risk factors with focus on cardiovascular disease.

Transportation noise pollution and cardiovascular disease

Epidemiological studies have found that transportation noise increases the risk of cardiovascular morbidity and mortality, with high-quality evidence for ischaemic heart disease. According to the WHO, ≥1.6 million healthy life-years are lost annually from traffic-related noise in Western Europe. Traffic noise at night causes fragmentation and shortening of sleep, elevation of stress hormone levels, and increased oxidative stress in the vasculature and the brain. These factors can promote vascular dysfunction, inflammation and hypertension, thereby elevating the risk of cardiovascular disease. In this Review, we focus on the indirect, non-auditory cardiovascular health effects of transportation noise. We provide an updated overview of epidemiological research on the effects of transportation noise on cardiovascular risk factors and disease, discuss the mechanistic insights from the latest clinical and experimental studies, and propose new risk markers to address noise-induced cardiovascular effects in the general population. We also explain, in detail, the potential effects of noise on alterations of gene networks, epigenetic pathways, gut microbiota, circadian rhythm, signal transduction along the neuronal-cardiovascular axis, oxidative stress, inflammation and metabolism. Lastly, we describe current and future noise-mitigation strategies and evaluate the status of the existing evidence on noise as a cardiovascular risk factor.

Oxidative stress and inflammation contribute to traffic noise-induced vascular and cerebral dysfunction via uncoupling of nitric oxide synthases

Environmental pollution and non-chemical stressors such as mental stress or traffic noise exposure are increasingly accepted as health risk factors with substantial contribution to chronic noncommunicable diseases (e.g. cardiovascular, metabolic and mental). Whereas the mechanisms of air pollution-mediated adverse health effects are well characterized, the mechanisms of traffic noise exposure are not completely understood, despite convincing clinical and epidemiological evidence for a significant contribution of environmental noise to overall mortality and disability. The initial mechanism of noise-induced cardiovascular, metabolic and mental disease is well defined by the „noise reaction model“ and consists of neuronal activation involving the hypothalamic-pituitary-adrenal (HPA) axis as well as the sympathetic nervous system, followed by a classical stress response via cortisol and catecholamines. Stress pathways are initiated by noise-induced annoyance and sleep deprivation/fragmentation. This review highlights the down-stream pathophysiology of noise-induced mental stress, which is based on an induction of inflammation and oxidative stress. We highlight the sources of reactive oxygen species (ROS) involved and the known targets for noise-induced oxidative damage. Part of the review emphasizes noise-triggered uncoupling/dysregulation of endothelial and neuronal nitric oxide synthase (eNOS and nNOS) and its central role for vascular dysfunction.

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Exposure to (traffic) noise causes non-auditory (indirect) cardiovascular and cerebral health harms via neuronal activation.

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Noise activates the HPA axis and sympathetic nervous system increasing levels of stress hormones, vasoconstrictors and ROS.

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Noise induces inflammation and stimulates several ROS sources leading to cerebral and cardiovascular oxidative damage.

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Noise leads to eNOS and nNOS uncoupling contributing to cardiometabolic disease and cognitive impairment.

Environmental noise induces the release of stress hormones and inflammatory signaling molecules leading to oxidative stress and vascular dysfunction-Signatures of the internal exposome

Environmental noise is a well-recognized health risk and part of the external exposome-the World Health Organization estimates that 1 million healthy life years are lost annually in Western Europe alone due to noise-related complications, including increased incidence of hypertension, heart failure, myocardial infarction, and stroke. Previous data suggest that noise works through two paired pathways in a proposed reaction model for noise exposure. As a nonspecific stressor, chronic low-level noise exposure can cause a disruption of sleep and communication leading to annoyance and subsequent sympathetic and endocrine stress responses leading to increased blood pressure, heart rate, stress hormone levels, and in particular more oxidative stress, being responsible for vascular dysfunction and representing changes of the internal exposome. Chronic stress generates cardiovascular risk factors on its own such as increased blood pressure, blood viscosity, blood glucose, and activation of blood coagulation. To this end, persistent chronic noise exposure increases cardiometabolic diseases, including arterial hypertension, coronary artery disease, arrhythmia, heart failure, diabetes mellitus type 2, and stroke. The present review discusses the mechanisms of the nonauditory noise-induced cardiovascular and metabolic consequences, focusing on mental stress signaling pathways, activation of the hypothalamic-pituitary-adrenocortical axis and sympathetic nervous system, the association of these activations with inflammation, and the subsequent onset of oxidative stress and vascular dysfunction. © 2019 BioFactors, 45 (4):495-506, 2019.

Perceived discrimination and cardiovascular health disparities: a multisystem review and health neuroscience perspective

There are distinct racial disparities in cardiovascular disease (CVD) risk, with Black individuals at much greater risk than White individuals. Although many factors contribute to these disparities, recent attention has focused on the role of discrimination as a stress-related factor that contributes to racial disparities in CVD. As such, it is important to understand the mechanisms by which discrimination might affect CVD. Recent studies have examined these mechanisms by focusing on neurobiological mediators of CVD risk. Given this increase in studies, a systematic review of perceived discrimination and neurobiological mediators of CVD risk is warranted. Our review uses a multisystem approach to review studies on the relationship between perceived discrimination and (1) cardiovascular responses to stress, (2) hypothalamic-pituitary-adrenocortical axis function, and (3) the immune system, as well as (4) the brain systems thought to regulate these parameters of peripheral physiology. In addition to summarizing existing evidence, our review integrates these findings into a conceptual model describing multidirectional pathways linking perceived discrimination with a CVD risk.

Neuroimmunomodulation in depression: a review of inflammatory cytokines involved in this process

Depression is a debilitating mental disease that affects a large number of people globally; however the pathophysiological mechanisms of this disease remain incompletely understood. Some studies have shown that depression is associated with inflammatory activity, and the mode of action of several antidepressants appears to involve immunomodulation. In this case, the induction of a pro-inflammatory state in healthy or depressive subjects induces a 'sickness behaviour' resembling depressive symptomatology. Potential mechanisms of pro-inflammatory cytokines are effects on monoamine levels, disruption of the hypothalamic-pituitary-adrenal axis, activation of the pathological microglial cells, such as the macrophages and alterations in neuroplasticity and brain functions. Thus, this review will highlight the role of inflammation in depression, the possible mechanisms involved, and also explore effective treatments that act on the immune system.

Change in the health of tsunami-exposed mothers three years after the natural disaster

BACKGROUND

Women's experiences with secondary stressors resulting from natural disasters, such as increased economic insecurity, expanded caregiving responsibilities and disrupted family life, may contribute to women's mental and physical health problems.

AIMS

The present study investigates change and stability in post-tsunami depressive symptoms and perceived physical health of tsunami-exposed mothers over three and a half years.

METHODS

Using data from 160 tsunami-affected mothers, the present study uses structural equation modelling to investigate (1) change, stability, cross-lagged reciprocal influences of mental and physical health and (2) the meditation effect of negative life events on the relationship between tsunami exposure and post-tsunami depressive symptoms and perceived physical health of tsunami-exposed mothers from 2005 to 2008.

RESULTS

Tsunami exposure contributed to depressive symptoms among mothers independently of pre-tsunami family adversities. Average depressive symptoms showed a decline whereas poor physical health showed an increase over this period. The results also revealed an interrelated health process between depression and physical health over time. Continuity of health problems were mediated by secondary stressors that also exerted an additive effect on later health problems.

CONCLUSIONS

Post-disaster intervention and recovery programmes should focus not only on mothers' exposure to natural disasters, but also their pre- and post-natural disaster adversities. They should reach disaster-exposed mothers directly and have an integrated health approach to disrupt continuities of health problems.

Decrease of CD4(+)FOXP3(+) T regulatory cells in the peripheral blood of human subjects undergoing a mental stressor

We have previously shown that acute psychological stress alerts the adaptive immune response causing an increase in antigen-experienced effector T cells in the peripheral blood. T regulatory cells (Tregs) play a central role in maintaining self-tolerance and controlling autoimmune responses. Here, we analyzed for the first time the behaviour of Tregs in the context of a stress-induced activation of the adaptive immune response. 31 healthy young males underwent a brief laboratory stressor and, in a crossover design, served as their own unstressed controls. We quantified effects of acute stress on CD4(+)FOXP3(+) T regulatory cells and other T cell subpopulations using flow cytometry. In addition, the expression of Treg-related effector molecules and stress hormone receptors were analyzed in the subjects' peripheral T cells. We confirmed our previous observation of a stress-induced decrease in CD45RA(+)CCR7(+) "naïve" and CD45RA(-)CCR7+ "central memory" T cells while CD45RA(-)-CCR7(-) "memory effector" and CD45RA(+)CCR7(-) "terminally differentiated" effector T cells remained stable or increased. Importantly, we found acute psychological stress to cause a concomitant decrease in CD4(+)FOXP3(+) Tregs and in CD4(+) T cells expressing Treg-related effector molecules cytotoxic T-lymphocyte antigen-4 (CTLA-4) and latency associated peptide (LAP). Finally, we observed beta(1)-adrenergic and glucorticoid alpha receptors to be overexpressed in Tregs, suggesting that these molecules might mediate stress-related effects on Tregs. In conclusion, inhibiting components of the adaptive immune response, like Tregs, are down-regulated during a stress-induced activation of the adaptive immune response. In situations of chronic stress, this scenario might result in an exacerbation of inflammatory conditions such as autoimmune diseases.

Perioperative pain, psychological distress, and immune function in men undergoing prostatectomy for cancer of the prostate

Prostate cancer is a leading malignancy in men, and prostatectomy is widely used for its treatment. Psychological distress and pain are commonly experienced in the perioperative period, and both can contribute to suppression of the immune response to cancer. This study evaluated perioperative pain, psychological distress, and immune function in men undergoing prostatectomy. Men were evaluated prior to surgery, 1 and 2 days postoperatively and 4-6 weeks postoperatively. Compared to cancer-free men, the prostatectomy group reported increased perceived stress, depression, confusion, and anxiety prior to surgery. During the 2 postoperative days, mood disturbance and anxiety persisted and were accompanied by mild elevations in pain and reduced vigor. At 4-6 weeks postoperative, mood, pain, and immune function were similar to those of the cancer-free group; however, the prostatectomy group continued to report significant elevations in anxiety. Natural killer cell activity (NKCA) was significantly reduced on Day 1 after prostatectomy, but by postoperative Day 2, NKCA returned to a level similar to that of the cancer-free group. The reduction in NKCA was not accompanied by changes in circulating immune cells, demonstrating that this reduction represented a functional change in NKCA. No correlations between immune variables and pain or psychological variables were found, suggesting that the postoperative reduction in NKCA was likely the result of the physical stress of the surgical experience. Suppression of immune defenses during the critical postoperative period can place cancer patients at risk for nascent tumor seeding. Additional interventions are needed to reduce this risk.

Previous trauma exposure and PTSD symptoms as predictors of subjective and biological response to stress

OBJECTIVE

The immediate and long-term effects of traumatic exposure and subsequent posttraumatic stress reactions in people in high-risk occupations are well-documented. What is less evident is the impact of this traumatic exposure and subsequent traumatic stress symptoms on workers' response to acute stress situations. This study aimed to examine the association between prior traumatic exposure related to policing, current posttraumatic stress symptoms and biological markers of stress, and subjective appraisal of stress before, during, and after exposure to acutely stressful stimuli.

METHOD

A stressful policing situation was created through the use of a video simulator room. Participants' responses to the simulated emergency were evaluated by monitoring heart rate, collecting salivatory samples for cortisol analysis, and repeated administration of a subjective measure of anxiety.

RESULTS

Biological indicators of stress, as measured by cortisol level and heart rate, were not associated with previous trauma exposure or trauma symptoms; however, biological response was associated with subjective anxiety. Vulnerability to psychological stress responses during an acute stress situation was also associated with lower levels of social support, previous traumatic exposures, and preexisting symptoms of traumatic stress. The importance of these factors became more pronounced as time progressed after the event.

CONCLUSION

Previous trauma exposure did not put individuals at increased risk of biological distress during an acute stress situation. However, previous trauma and reduced social supports were associated with continuing psychological distress, confirming previous research and raising concerns about the cumulative negative effects of traumatic exposure on psychological health in emergency responders.

Regulation of lymphocytes redistribution via autonomic nervous activity during stochastic learning

Several studies reported that redistribution of lymphocyte subsets, especially CD3-CD16+CD56+ natural killer (NK) cells, was elicited by acute psychological stress tasks. It is known that lymphocyte redistribution was regulated based on active or passive emotional coping strategies, which can be elicited dependent on controllability of a stressor. Controllability can be evaluated gradually by learning of a contingency between actions and outcomes. Therefore, lymphocyte redistribution can be determined by learning of the contingency. To examine this issue, we used a stochastic learning task as an acute stress task and divided twenty healthy participants into reinforcement or yoked groups. Between the two groups, only whether they could learn the contingency was manipulated. As a result, patterns of changes in the NK cell numbers differed between the groups; NK cells remarkably increased at first and then gradually decreased to the baseline in the reinforcement group while the yoked group showed a moderate but sustained increase of NK cells. These patterns of changes in the NK cells were completely parallel with changes of the cardiovascular parameters but not with secretion of catecholamines. The present results suggest that cardiovascular and immune reactivity can be modulated along with progresses of adaptation for an acute stressor.

Randomized clinical trial examining the effect of music therapy in stress response to day surgery

Background

Music therapy could reduce stress and the stress response. The aim of this study was to investigate the role of music therapy in alleviating stress during day surgery.

Methods

Sixty patients undergoing day surgery were randomized to one of three groups, each containing 20 patients. Before and during surgery, patients in group 1 listened to new age music and those in group 2 listened to a choice of music from one of four styles. Patients in group 3 (control group) heard the normal sounds of the operating theatre. Plasma levels of cortisol and subpopulations of lymphocytes were evaluated before, during and after operation.

Results

Plasma cortisol levels decreased during operation in both groups of patients who listened to music, but increased in the control group. Postoperative cortisol levels were significantly higher in group 1 than in group 2 (mean(s.d.) 14·21(6·96) versus 8·63(2·72) ng/dl respectively; P &lt; 0·050). Levels of natural killer lymphocytes decreased during surgery in groups 1 and 2, but increased in controls. Intraoperative levels of natural killer cells were significantly lower in group 1 than in group 3 (mean(s.d.) 212·2(89·3) versus 329·1(167·8) cells/µl; P &lt; 0·050).

Conclusion

Perioperative music therapy changed the neurohormonal and immune stress response to day surgery, especially when the type of music was selected by the patient.

The role of stress in asthma: insight from studies on the effect of acute and chronic stressors in models of airway inflammation

Asthma, a chronic inflammatory disease of the airways, is greatly influenced by psychosocial factors and stress. This review looks at clinical studies that have shown strong associations between psychological stress and asthma to identify potential mechanisms for these interactions. Furthermore, we review animal studies involving stress and airway inflammation or airway hyperresponsiveness, and discuss possible mechanisms of stress action in asthma. In conclusion, further research, both in humans and in animal models, into the mechanisms of stress-induced changes in asthma exacerbation are required to help better understand the complex makeup of asthma and assist in the development of therapies directed at the interplay between the nervous system and airway inflammation.

Lymphocyte subsets, cardiovascular measures and anxiety state before and after a professional examination

Controversies exist regarding the impact of psychological stress on the functioning of the immune system in humans. The aim of the present study, therefore, was to evaluate whether the condition of a pre-exam stress may or not modify resting lymphocyte subsets, as well as blood pressure and heart rate. About 22 medical residents of both sexes not suffering from any medical or psychiatric disorder were included in the study. Anxiety levels were measured by means of the Hamilton rating scale for anxiety (HRSA) and anxiety traits by means of the panic-agoraphobic spectrum self-report (PAS-SR) version and the obsessive-compulsive spectrum self-report (OBS-SR) version. The results showed that systolic blood pressure and heart rate increased significantly just before sitting an examination (t(1)) in all subjects, as compared with a calm situation (t(2)), in parallel with the increase in the HRSA total score, while no significant difference was observed in lymphocyte subsets at the two assessment times. However, men had a higher number of CD4+ cells than women at t(1) and t(2), while women showed a higher heart rate at t(1). In addition, significant correlations between CD4+ lymphocyte count and heart rate at t(1) or HRSA at t(2) were detected. These findings indicate that the acute stress determined by sitting for examination provokes changes in autonomic nervous system parameters, such as blood pressure and heart rate, as well as in the subjective feeling of anxiety, as shown by the increased HRSA total scores, which were not paralleled by modifications of lymphocyte subsets. However, individual differences, related to both sex and personality traits yet to be identified, seem to have an impact in shaping the stress response.

Effect of coping on endocrinoimmune functions in different stress situations

The objective of this study was to examine the effects of coping strategies on the endocrine and immune functions in different stress situations. Thirty-eight medical students were enrolled in this study. Cell-mediated immune function was measured using the lymphocyte proliferative response to phytohemagglutinin (PHA) and interleukin-2 (IL-2) production during the nonexamination period and during the preexamination period. Endocrine functions were assessed by measuring the plasma levels of norepinephrine, adrenocorticotropic hormone (ACTH) and cortisol. The Global Assessment of Recent Stress (GARS) scale, the Stress Response Inventory, the anxiety, depression, and somatization subscales of the Symptom Checklist-90-revised, the Way of Coping-revised, the Toronto Alexithymia Scale and the Anger Expression Scale were used as psychometric measures. The subjects with higher levels of total GARS scores showed significantly higher IL-2 production during the nonexam period than those with lower levels of total GARS scores. During the same period, IL-2 production in the less positive reappraisal group was significantly higher than in the more positive reappraisal group. Lymphocyte proliferation in the group seeking less social support was also significantly higher than in the group seeking more social support. However, no significant association was found between the coping strategies and each of the hormone levels. These results suggest that positive reappraisal and seeking social support can be associated with the alteration of immune function during a chronic stress period. In particular, positive reappraisal is likely to reverse the stress-induced immune responses. This study did not find that neuroendocrine function such as the sympathetic-adrenal medullary axis or the hypothalamic-pituitary-adrenal axis is playing a mediating role in the relationship between coping and immunity.

L-Theanine reduces psychological and physiological stress responses

L-Theanine is an amino acid contained in green tea leaves which is known to block the binding of L-glutamic acid to glutamate receptors in the brain. Because the characteristics of L-Theanine suggest that it may influence psychological and physiological states under stress, the present study examined these possible effects in a laboratory setting using a mental arithmetic task as an acute stressor. Twelve participants underwent four separate trials: one in which they took L-Theanine at the start of an experimental procedure, one in which they took L-Theanine midway, and two control trials in which they either took a placebo or nothing. The experimental sessions were performed by double-blind, and the order of them was counterbalanced. The results showed that L-Theanine intake resulted in a reduction in the heart rate (HR) and salivary immunoglobulin A (s-IgA) responses to an acute stress task relative to the placebo control condition. Moreover, analyses of heart rate variability indicated that the reductions in HR and s-IgA were likely attributable to an attenuation of sympathetic nervous activation. Thus, it was suggested that the oral intake of L-Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation.

Gender difference in basal and stress levels of peripheral blood leukocytes in laboratory rats

The aim of the present study was to investigate gender differences in numbers and function of blood immune cells in stressed and non-stressed laboratory rats. Psychosocial stress in adult male or female rats was induced by social confrontation of an intruder rat with a resident opponent for 2 h. Behavioral analysis indicated that intruders of both sexes were clearly defeated and had markedly higher plasma corticosterone concentrations than unstressed home cage controls at the end of the confrontation. Lower numbers of CD4, CD8, and B cells as well as a reduced proliferative response of lymphocytes to ConA were observed in stressed groups of either sex. However, some important gender differences were also observed. Stressed males had higher granulocyte numbers than controls, while granulocyte numbers remained unchanged in stressed females. Similarly, stressed males had higher phagocytic activity than stressed females. Second, there was a gender difference in some basal values. Female controls had lower NK cell numbers than control males. Interestingly, NK numbers in stressed males decreased considerably, reaching the same low levels as in (stressed and control) females. In addition, females exhibited higher basal corticosterone concentrations than males. To summarise, these data do not indicate a superior blood cellular immune function in female rats, neither for the control nor the stress condition. However, the data clearly suggest that male and female rats should not be considered as a uniform group with respect to their immunological response to stress.

Changes in family financial circumstances and the physical health of married and recently divorced mothers

This study investigates how divorce followed by single parenthood undermines the long-term physical health of rural mothers using four waves of survey data collected in Iowa, USA from 336 married and 80 divorced mothers during a 10-year period. Findings generally support the hypothesized pathways in that single-parenthood creates financial difficulties for rural mothers. Furthermore, this financial adversity is linked to self-assessed physical health trajectories that then contribute to change in morbidity. This reflects the developmental course of morbidity during the middle years. Methodologically, this extends existing research on the association between women's marital status and well being by explicitly examining individual trajectories of change in family financial strain and physical health, as well as by examining the dynamic association between both during the middle years.

Acute psychological stress alerts the adaptive immune response: Stress-induced mobilization of effector T cells

Influences of psychological stress on the acquired immune system have not consequently been investigated. We found acute psychological stress to cause an increase in CD56+ and CCR5+ effector T cells in the peripheral blood of healthy human subjects (N=22), while skin-homing CLA+ T cells decreased. At the same time, we observed a stress-induced decrease in CD45RA+/CCR7+ naive and CD45RA-/CCR7+ central memory T cells, while CD45RA-/CCR7- effector memory and CD45RA+/CCR7- terminally differentiated T cells increased. This T cell redistribution translated into an increase in T cells expressing perforin/granzyme B and in Epstein-Barr virus-specific, cytomegalovirus-specific and influenza virus-specific CD8+ T cells. Thus, acute stress seems to promote the retention of less mature T cells within lymphoid tissue or skin while effector-type T cells are mobilized into the blood in order to be able to rapidly migrate into peripheral tissues.

Gendered trajectories of work control and health outcomes in the middle years: a perspective from the rural Midwest

OBJECTIVE

The objective was to investigate whether increasing health heterogeneity during the middle years is attributed, at least in part, to the influence of varying levels of, and changes in, work control of the current midlife cohort.

METHOD

The study used four waves of data collected from 372 employed rural women and 320 employed men of the midlife cohort during a 10-year period. Variables included self-reported work control, stressful nonwork life events, and mental and physical health. The analyses used latent growth curve modeling.

RESULTS

The results partially supported the hypothesized pathways. For middle-aged men, work control directly influences health outcomes, whereas for middle-aged women work control indirectly influences health outcomes through the occurrence of stressful life events.

DISCUSSION

Through understanding these processes, work can be better designed to promote positive health outcomes, minimize negative health outcomes, and allow for better formulation and more effective implementation of health promotional programs.

Relations of plasma ACTH and cortisol levels with the distribution and function of peripheral blood cells in response to a behavioral challenge in breast cancer: an empirical exploration by means of statistical modeling

This study explores by means of statistical modeling the relations between adrenocorticotrophin hormone (ACTH) and cortisol levels and distribution and function of peripheral blood cells in response to an acute stressor consisting of a standardized speech task in breast cancer patients with axillary lymph node metastases and distant metastases. As a control group age-matched women participated in this study. The preliminary findings show that the effect of ACTH on immunoreactivity is related to the health of the doctor. In node-positive breast cancer patients and healthy women, ACTH has a modest positive effect on T lymphocyte percentages and on pokeweed-induced proliferation at baseline and in response to the speech task. In contrast, in breast cancer patients with distant metastases, ACTH has a negative effect on T lymphocyte and function at baseline and in response to the stressor. Interestingly, neither ACTH nor cortisol levels were related to natural killer (NK) cell percentages and natural killer cell activity (NKCA). In addition, it appeared that cortisol had a positive effect on CD3 cell percentages when the health of the donor was taken into account. This effect was most distinct on CD3 cells measured at baseline. If replicated on a larger scale, these findings may indicate that the hypothalamic pituitary adrenal axis plays a role in the adaptation of the host defenses in reaction to acute stress, particularly those involving T lymphocytes. Moreover, these findings may suggest that the health of the donor may be an important effect modification factor in the relations between neuroendocrines and immunoreactivity.

Temporal variation of acute stress responses in sympathetic nervous and immune systems

Sympathetic nervous activity plays a prominent role in acute stress responses in the immune system, enhancement of innate immunity and suppression of specific immunity. The present study was conducted to examine the temporal characteristics of such immune responses to acute stress and to determine their association with sympathetic activity in detail. For this purpose, 15 female undergraduates engaged in a continuous mental arithmetic task for 14 min, and we collected their blood samples for immune indices (CD3+ T cells, CD4+ T cells, NK cells) each 3 min during the task and saliva samples before and after the task. Our results showed that the proportion of Natural Killer cells (NK cells) increased even 2 min after initiation of the task, whereas proportions of CD3+ and CD4+ lymphocytes decreased 8 min after initiation of the task. Moreover, we found significant correlations between cardiovascular activity and the variations of immune indices.

Psychophysiological Reactivity under Mental Stress in Atopic Dermatitis

BACKGROUND

An association of mental stress with atopic dermatitis is widely accepted. However, no long-term evaluation of psychophysiological reactivity over the course of disease has yet been performed.

OBJECTIVE

We examined whether atopic dermatitis patients have an increased psychophysiological reactivity compared to healthy controls and in between acute and disease-free phases, and whether they differ in psychological state and trait variables.

METHODS

Fifteen patients with atopic dermatitis underwent a stress test during acute exacerbation and after symptom improvement and were compared to matched controls.

RESULTS

Psychophysiological responses to stress were not stronger in the patient group than in the controls. Nevertheless, the patients had a higher heart rate and lower vagal activity throughout the resting and stress phases at both examination times. The patients showed significantly higher anxiety, depression and emotional excitability, and self-ratings of inactivity clearly distinguished acute phases from remission.

CONCLUSION

There is an increased vegetative excitability level in patients with atopic dermatitis, which cannot be attributed solely to increased disease activity.

Heart rate variability

BACKGROUND

The authors conducted a study to evaluate the sensitivity of heart rate variability, or HRV, in quantifying the cardiocirculatory reaction to dental stress compared with other clinical parameters more frequently used in clinical practice.

METHODS

Twenty-five healthy subjects (15 men and 10 women aged 19 through 73 years) who underwent dental extractions were enrolled in the study. The authors measured systolic blood pressure, or SBP; diastolic blood pressure, or DBP; heart rate, or HR; and HRV at baseline, immediately after local anesthetic was administered, during the dental extraction and five minutes after the dental extraction. Time domain measures of HRV were based on interbeat intervals and were obtained by using standard deviations of the R-R intervals, which were calculated during a five-minute period in a continuous electrocardiographic record.

RESULTS

Analysis of variance for repeated measures showed no time-related difference between the four study periods with regard to SBP and DBP. However, HR values were significantly different in three of the four periods, and HRV values were significantly different in all four testing periods. Furthermore, HRV values exhibited greater variability in the maximum changes recorded during dental extractions compared with HR values (0 to 80 milliseconds versus 0 to 31 beats/minute, respectively).

CONCLUSIONS

HRV is a highly sensitive parameter for quantifying the sympathetic drive to the heart during a cardiovascular reaction to a dental operation.

CLINICAL IMPLICATIONS

Clinicians may find that HRV evaluation is useful in monitoring patients with heart disease to detect early signs of cardiac impairment related to local, high sympathetic activity and to prevent cardiovascular emergencies.

Alternative modalities for asthma that reduce stress and modify mood states: evidence for underlying psychobiologic mechanisms

OBJECTIVE

To review the evidence supporting a role for psychological interventions in the treatment of asthma, with particular emphasis on underlying psychobiological mechanisms.

DATA SOURCES

Independent literature searches on MEDLINE, PREMEDLINE, Cochrane Library, and PSYCHINFO from their respective inception to 2003 were performed. Separate searches were performed for psychological stress and asthma, psychoneuroimmunology and asthma, stress management, relaxation, asthma, complementary and alternative medicine and asthma, and immune function and psychological intervention. The search was not limited based on language of publication.

STUDY SELECTION

Supportive evidence from overlapping research was included based on the expert opinion of the author and through discussions with consultants in the field.

RESULTS

This review first discusses human and animal studies focused on psychological stress and the effects of stress on the neuroendocrine and immune system, emphasizing the implication of these effects on asthma. Second, studies that evaluated the influence of stress reduction modalities on neuroendocrine and immune function were examined. Existing evidence from human clinical studies that explored the role of psychological interventions for asthma is reexamined in this context.

CONCLUSIONS

A growing appreciation of the interactions among behavioral, neural, endocrine, and immune processes suggests possible mechanisms through which psychological interventions for asthma may be operating. This review provides a framework in which we can begin to see links among these systems that might provide new insights to guide future explorations.

Psychological stress and the human immune system: a meta-analytic study of 30 years of inquiry

The present report meta-analyzes more than 300 empirical articles describing a relationship between psychological stress and parameters of the immune system in human participants. Acute stressors (lasting minutes) were associated with potentially adaptive upregulation of some parameters of natural immunity and downregulation of some functions of specific immunity. Brief naturalistic stressors (such as exams) tended to suppress cellular immunity while preserving humoral immunity. Chronic stressors were associated with suppression of both cellular and humoral measures. Effects of event sequences varied according to the kind of event (trauma vs. loss). Subjective reports of stress generally did not associate with immune change. In some cases, physical vulnerability as a function of age or disease also increased vulnerability to immune change during stressors.

Psychological stress and the human immune system: a meta-analytic study of 30 years of inquiry

The present report meta-analyzes more than 300 empirical articles describing a relationship between psychological stress and parameters of the immune system in human participants. Acute stressors (lasting minutes) were associated with potentially adaptive upregulation of some parameters of natural immunity and downregulation of some functions of specific immunity. Brief naturalistic stressors (such as exams) tended to suppress cellular immunity while preserving humoral immunity. Chronic stressors were associated with suppression of both cellular and humoral measures. Effects of event sequences varied according to the kind of event (trauma vs. loss). Subjective reports of stress generally did not associate with immune change. In some cases, physical vulnerability as a function of age or disease also increased vulnerability to immune change during stressors.

Sex differences in immune responses and immune reactivity to stress in adolescents

The immune system is the body's major defense mechanism against disease. However, psychosocial factors, such as stress, can modulate various immune responses. Although they have been examined in adult humans and other animals, sex differences in immune responses and immune reactivity to stress have rarely been examined in adolescents, particularly comparing healthy and asthmatic adolescents. In 151 healthy and asthmatic high school adolescents (91 females and 60 males), natural killer cell (NK) cytotoxicity, polymorphonuclear leukocyte (PMN) superoxide release, lymphocyte proliferative responses, and CD subsets were measured twice: once during mid-semester and again during final examinations. There was little difference in these measures between healthy and asthmatic adolescents. Similarly, only sex difference was noted in NK cytotoxicity at a 25:1 effector-to-target cell ratio, with males showing significantly higher responses than females. For PMN superoxide release, females significantly increased their responses during final examinations, whereas males demonstrated no changes. For lymphocyte proliferative responses, both females and males increased their responses during final examinations, but the magnitude of increase was much greater in males. Furthermore, racial comparisons indicated that African American adolescents (n = 16), as compared with Caucasian adolescents (n = 128), had significantly higher responses in PMN superoxide release to N-Formyl-Met-Leu-Phe (FMLP) activation during mid-semester and lymphocyte proliferative responses at both time points. Nevertheless, the overall findings indicate limited differences in immune responses and immune reactivity to stress in adolescents between males and females, healthy and asthmatic adolescents, and Caucasians and African Americans. However, further investigations with larger samples are warranted.

Effects of acute stress, relaxation, and a neurogenic inflammatory stimulus on interleukin-6 in humans

Effects of three experimental manipulations: mental stress, relaxation, and a nociceptive inflammatory stimulus, capsaicin, on levels of interleukin-6 (IL-6) were examined. Fifty subjects were pre-trained in relaxation and then randomized to a stress (Stroop test), relaxation (tape), or control (video) manipulation. Subjects participated in an evening reactivity session including 20 min of stress, relaxation, or control followed by a capsaicin injection in the forearm. Cardiovascular variables and levels of IL-6 were measured before and after the manipulation, and at regular intervals up to 60 min post-capsaicin. Group assignment did not differentially affect change in IL-6 over time, either before or after capsaicin. Small but significant increases in IL-6 were seen at 60 min post-capsaicin. These findings suggest that an acute stress manipulation does not modulate IL-6 within this time frame. Although IL-6 did increase following a neurogenic inflammatory stimulus, it did so subsequent to the maximum flare, suggesting that flare mechanisms are independent of IL-6.

Stable individual differences in physiological response to stressors: implications for stress-elicited changes in immune related health

Stress reactivity refers to a stable individual difference in response to stressors. This article addresses three questions about reactivity: (1) Are cardiovascular, endocrine, and immune responses to acute laboratory stressors stable over time and across stressor tasks? (2) Are cardiovascular, endocrine, and immune reactors the same people? and (3) Are reactive people more vulnerable to stressor-induced effects on susceptibility to infectious disease? We conclude that for many individual indicators of physiological responsiveness to stressors there is moderate stability over time and across stressor tasks indicating the possible existence of underlying dispositional characteristics; the commonality of immune and cardiovascular and hormonal responses to stress depend on the nature of regulation of the immune response being assessed; reactivity appears to have implications for vulnerability to stressor-associated disease risk (stress-by-reactivity interaction) in the natural environment, but the exact nature of this vulnerability is not as yet entirely clear.

Opposing effects of short- and long-term stress on airway inflammation

Between 20% and 35% of subjects with asthma experience asthma exacerbations during periods of stress. The biological mechanisms underlying these exacerbations are not clearly understood, and the role of psychologic factors in the pathophysiology of asthma remains controversial. We investigated the ability of psychologic stress to modulate airway inflammation and airway hyperresponsiveness (AHR) to methacholine in a murine model of asthma. Animals were exposed to a stressor daily for 3 (short-term stress) or 7 (long-term stress) days. After allergen challenge, AHR was assessed through plethysmography, and bronchoalveolar lavage cells were counted as a measure of inflammation. After short-term stress, inflammatory cell number was decreased compared with unstressed animals, whereas levels of interleukin (IL)-6, IL-9, and IL-13 were increased. Administration of a corticosteroid receptor antagonist, before stress, prevented the decrease in inflammatory cell numbers. In contrast, animals stressed for 7 consecutive days showed a significant increase in inflammatory cell numbers, which was independent of the glucocorticoid response, but no change in cytokine levels. AHR was not altered in stressed animals. Our results indicate that repeated exposure to stress over the long term engages different mechanisms than short-term stress and can exacerbate the chronic inflammatory responses of the airway.

Acute psychological stress induces a prolonged suppression of the production of reactive oxygen species by phagocytes

Possible effects of psychological stress on the function of phagocytic cells have thus far hardly been investigated. In this study, we examined the phagocytic production of reactive oxygen species (ROS) in 10 healthy subjects undergoing a brief mental stressor. In a crossover design, the same subjects served as their own unstressed controls on a second experimental date. The acute laboratory stress resulted in a suppressed circadian rhythm of ROS production and in a decreased overall formation of ROS throughout the day. Especially under conditions of chronic stress, this finding may be of importance for the host's defense against infectious diseases.

The effects of acute psychological stress on lymphocyte adhesion molecule expression and density in cardiac versus vascular reactors

This study examined the effects of acute psychological stress on lymphocyte subsets and their differential changes according to their cell adhesion molecule expression in cardiac versus vascular reactors. We classified 49 subjects into cardiac or vascular reactors based on the participants' cardiac output or total peripheral resistance reactivity to a speech presentation task. Analysis demonstrated that there were no significant differences in lymphocyte counts or adhesion molecule expression between cardiac and vascular reactors at rest. Cardiac reactors showed a significant decrease of surface density of CD62L on mixed lymphocytes (p <.001) as well as on CD4 (p <.01) and CD8 T-cells (p <.001). There was also a disproportionate increase in the number of CD62L(-) T cells compared to CD62L(+) T cells only in cardiac reactors (p <.001). There were no significant effects of the stressor observed in vascular responders. The findings replicate previous studies demonstrating associations between cardiovascular and immune responses to acute stress and extends those findings by suggesting that the relationship is more significant in individuals who increase their blood pressure primarily through a cardiac mechanism.

Catecholamines inhibit the antigen-presenting capability of epidermal Langerhans cells

The sympathetic nervous system modulates immune function at a number of levels. Within the epidermis, APCs (Langerhans cells (LC)) are frequently anatomically associated with peripheral nerves. Furthermore, some neuropeptides have been shown to regulate LC Ag-presenting function. We explored the expression of adrenergic receptors (AR) in murine LC and assessed their functional role on Ag presentation and modulation of cutaneous immune responses. Both purified LC and the LC-like cell lines XS52-4D and XS106 expressed mRNA for the ARs alpha(1A) and beta(2). XS106 cells and purified LC also expressed beta(1)-AR mRNA. Treatment of murine epidermal cell preparations with epinephrine (EPI) or norepinephrine inhibited Ag presentation in vitro. Furthermore, pretreatment of epidermal cells with EPI or norepinephrine in vitro suppressed the ability of these cells to present Ag for elicitation of delayed-type hypersensitivity in previously immunized mice. This effect was blocked by use of the beta(2)-adrenergic antagonist ICI 118,551 but not by the alpha-antagonist phentolamine. Local intradermal injection of EPI inhibited the induction of contact hypersensitivity to epicutaneously administered haptens. Surprisingly, injection of EPI at a distant site also suppressed induction of contact hypersensitivity. Thus, catecholamines may have both local and systemic effects. We conclude that specific ARs are expressed on LC and that signaling through these receptors can decrease epidermal immune reactions.

Temporal stability of acute stress-induced changes in leukocyte subsets and cellular adhesion molecules in older adults

This study investigated the temporal stability of enumerative immune and catecholamine responses to acute psychosocial stress in 67 Alzheimer's caregivers ages 56-82 years (45 women and 22 men) who were required to prepare and deliver two 3-min speeches on three occasions at 2-week and 6-week intervals. All leukocyte subsets and adhesion molecules (CD62L and CD11a) changed significantly from rest to postspeak at each of the three testing sessions (p's <.0005). Responses showed moderate to high temporal stability across baseline and absolute task values (r's =.65-.96). Reliability was predictably lower for both forms of change scores (r's = -.16-.64). The level of temporal stability achieved is comparable to that seen previously in younger adults, indicating that acute psychosocial stress produces reliable changes in circulating leukocytes and cell adhesion molecules in older adults.

Environmental stress mediates changes in neuroimmunological interactions

Combinations of environmental stress coordinately increase toxicological assaults on health, dependent on the genetics of the exposed organism. Multiple gene variances between individuals influence the risks associated with environmental exposures, and environmental stress presents in multiple forms including chemical, physical, and psychological stresses. Combined chemical, physical, and psychological stresses are suggested as exacerbating the initiation and/or duration of illnesses, and many of the detrimental outcomes on health are posited to relate to changes in neuroendocrine immune circuitry. However, most human epidemiological or experimental animal studies have not considered the combination of chemical, physical, and psychological stress on health status. Current consideration is being given to "real world" exposures for assessment of health risk, but this mainly relates to evaluation of chemical mixtures. In addition to concomitant chemical exposures having agonistic and/or antagonistic interactions, the physical and psychological status of the individual can influence exposure outcomes. An individual's psychosocial environment is likely to be important in epidemiological investigations. Neuroimmunology is a burgeoning discipline, and neurotoxicology and immunotoxicology studies should consider the bidirectional regulatory mechanisms between these organ systems and the potential long-term influences of psychological stress. This mini-review discusses some intriguing data from animal and human studies, which address the regulatory pathways between the neural, endocrine, and immune systems, with emphasis on psychological stress.

Acute psychological stress simultaneously alters hormone levels, recruitment of lymphocyte subsets, and production of reactive oxygen species

Very little is known about the effects of acute psychological stress on the production of reactive oxygen species (ROS) by human phagocytic cells and the interplay between subjectively perceived stress, mediating hormones, variations in the number of peripheral leukocytes and ROS production. We measured psychological reactions, cardiovascular parameters, plasma catecholamines, plasma prolactin and cortisol as well as peripheral lymphocyte subsets in 13 experimental subjects undergoing a brief psychological stressor, and production of ROS, as indicated by chemiluminescence (CL), in stressed subjects and in healthy controls. The stressor elevated anger (p<0.01) and cardiovascular activation (p<0.01). There were significant changes in plasma levels of cortisol (p<0.01) and prolactin (p<0.001). During psychological stress natural killer (NK) cells (p<0.01) and CD8/CD38 cells (p<0.05) increased and returned to baseline only 25 minutes later. Significant changes in the number of naive CD4+/CD45RA+ (p<0.01) and antigen-experienced CD8+/CD45RO+ T cells (p<0.05) occurred. Subjects with stronger cardiovascular reaction showed higher stress-related plasma levels of norepinephrine (p<0.05) and were mainly responsible for the increase in NK cells. We observed a significantly reduced production of ROS following the stress test (p<0.05). Our results show that psychological stress is expressed simultaneously on psychological, hormonal and immunological levels of the organism. We show the existence of a circadian rhythm leading to a pronounced increase in CL during the morning hours. This first study taking this circadian rhythm in account revealed a significant suppressive effect of stress on ROS production.

Reactivity and vulnerability to stress-associated risk for upper respiratory illness

OBJECTIVE

We tested the hypothesis that the greater a person's laboratory stress-elicited elevation in cortisol, the greater the life stress-related risk for upper respiratory infection (URI). We also tested the prediction that the greater the laboratory stress-elicited rise in natural killer cell (NK) cytotoxicity, the smaller the life stress-related URI risk. Finally, we explored whether sympathetic nervous system (SNS) and enumerative immune reactivities to laboratory stress moderate the relation between life stress and URI.

METHODS

At baseline, 115 healthy subjects were administered a negative stressful life events checklist and were tested to assess their SNS (blood pressure, heart rate, and catecholamines), HPA (cortisol), and immune (NK cell cytotoxicity and lymphocyte subsets) reactivities to laboratory speech tasks administered 2 weeks apart. Responses were averaged across the two laboratory assessments to create reactivity scores. After these assessments were completed, participants were followed weekly for 12 consecutive weeks. At each follow-up they completed a measure of perceived stress experienced over the last week. They were also instructed to contact the study coordinator if they had a cold or flu at any time during follow-up. A health care worker verified reported illnesses.

RESULTS

In a traditional prospective analysis, high cortisol reactors with high levels of life events had a greater incidence of verified URI than did high reactors with low levels of life events and low reactors irrespective of their life event scores. Using hierarchical linear modeling, CD8(+) number, Natural Killer (NK) cell number, and NK cell cytotoxicity, each interacted with weekly perceived stress levels in predicting concurrent occurrences of self-reported URIs. For these outcomes, low immune reactors were more likely to experience an URI during high stress than low stress weeks. High immune reactors did not exhibit differences in weekly URIs as a function of weekly stress level. The SNS reactivity markers did not moderate the association of stress and URI incidence in either analysis.

CONCLUSIONS

Acute HPA and immune responses to laboratory stressors are markers of how vulnerable people are to the increased risk for URI associated with stressors in the natural environment.

Cumulative abuse experiences, physical health and health behaviors

PURPOSE

Our purpose was to investigate the complex relationship between a range of lifetime abuse experiences with current physical health and health behaviors.

METHODS

Between October 1998 and May 1999, interviews were conducted with 557 ethnically diverse women seen at two urban primary care centers. Seven forms of abuse were measured: childhood physical and sexual abuse, past physical and sexual intimate partner violence (IPV), and recent emotional, physical, and sexual IPV. Severity was measured for six of these forms. Multiple non-specific physical symptoms were measured with a modified PRIME-MD, and four health behaviors were ascertained.

RESULTS

Approximately 10% of women never experiencing abuse reported multiple non-specific physical symptoms, compared with 25.8% to 78.4% of women reporting a range of abuse experiences. Increases in recent IPV, past IPV, child abuse, and economic hardship were associated with increases in reported symptoms. Women who experienced IPV were more likely to report smoking cigarettes, binge drinking, and having poor nutritional habits.

CONCLUSIONS

Recent IPV is associated with physical symptoms and risky health behaviors beyond the effects of child abuse, past IPV, and economic disadvantage. Understanding a person's IPV experiences may inform interventions for health behaviors, such as smoking cessation programs.

Psychoneuroimmunology and psychosomatic medicine: back to the future

OBJECTIVE

Although psychological modulation of immune function is now a well-established phenomenon, much of the relevant literature has been published within the last decade. This article speculates on future directions for psychoneuroimmunology research, after reviewing the history of the field.

METHODS

This review focuses on human psychoneuroimmunology studies published since 1939, particularly those that have appeared in Psychosomatic Medicine. Studies were clustered according to key themes, including stressor duration and characteristics (laboratory stressors, time-limited naturalistic stressors, or chronic stress), as well as the influences of psychopathology, personality, and interpersonal relationships; the responsiveness of the immune system to behavioral interventions is also addressed. Additionally, we describe trends in populations studied and the changing nature of immunological assessments. The final section focuses on health outcomes and future directions for the field.

RESULTS

There are now sufficient data to conclude that immune modulation by psychosocial stressors or interventions can lead to actual health changes, with the strongest direct evidence to date in infectious disease and wound healing. Furthermore, recent medical literature has highlighted a spectrum of diseases whose onset and course may be influenced by proinflammatory cytokines, from cardiovascular disease to frailty and functional decline; proinflammatory cytokine production can be directly stimulated by negative emotions and stressful experiences and indirectly stimulated by chronic or recurring infections. Accordingly, distress-related immune dysregulation may be one core mechanism behind a diverse set of health risks associated with negative emotions.

CONCLUSIONS

We suggest that psychoneuroimmunology may have broad implications for the basic biological sciences and medicine.

Bad is Stronger than Good

The greater power of bad events over good ones is found in everyday events, major life events (e.g., trauma), close relationship outcomes, social network patterns, interpersonal interactions, and learning processes. Bad emotions, bad parents, and bad feedback have more impact than good ones, and bad information is processed more thoroughly than good. The self is more motivated to avoid bad self-definitions than to pursue good ones. Bad impressions and bad stereotypes are quicker to form and more resistant to disconfirmation than good ones. Various explanations such as diagnosticity and salience help explain some findings, but the greater power of bad events is still found when such variables are controlled. Hardly any exceptions (indicating greater power of good) can be found. Taken together, these findings suggest that bad is stronger than good, as a general principle across a broad range of psychological phenomena.

Prolonged alpha-adrenergic stimulation causes changes in leukocyte distribution and lymphocyte apoptosis in the rat

We have previously shown in the rat model that acutely or chronically increased peripheral catecholamines lead to suppression of lymphocyte responsiveness via alpha(2)-adrenoceptor activation. Here we investigated the effects of alpha-adrenergic treatment on total leukocyte numbers and proportions of leukocyte subsets in peripheral blood and lymphoid tissues. It was found that a 12-h treatment with subcutaneously implanted tablets, one containing norepinephrine (NE) and one propranolol, leads to an increase in total blood leukocyte counts, due to a pronounced increase in granulocytes. In contrast, the numbers of all classes of lymphocytes other than NK cells were decreased. This decrease in blood lymphocytes is apparently not due to redistribution, since in the thymus, spleen, mesenteric and peripheral lymph nodes, the total numbers of lymphocytes were decreased as well, without any changes in subpopulations. Analogous results were obtained with rats adrenalectomized before the catecholamine treatment. Animals that received the alpha-adrenergic treatment displayed significantly more apoptotic cells in the lymphoid organs, as determined by the TUNEL technique. In the spleen, the enhanced rate of apoptosis was confined to the white pulp; red pulp areas exhibited significantly fewer apoptotic cells. Thus, an increased alpha-adrenergic tone in rats led to a general loss of lymphocytes due to lymphocyte directed apoptosis that was independent of glucocorticoids.

Cortisol mediates redistribution of CD8+ but not of CD56+ cells after the psychological stress of public speaking

The present study investigated the question if a pharmacological blockade of cortisol release with stress affects lymphocyte redistribution in healthy volunteers. It was expected that the well known increases in the number of CD8+ (T-suppressor/cytotoxic cells) and CD56+ (natural killer cells) after stress would not be downregulated in the absence of an appropriate cortisol response, since redistribution is markedly influenced by glucocorticoids. In a double blind design, forty healthy male volunteers were exposed to a brief psychological stressor (public speaking) and received a single oral dose of dexamethasone [DEX] (N=20) or placebo (N=20) the evening before the main experiment. Ratings on emotional states and blood samples for determination of hormones, CD8+, and CD56+ cell counts were obtained at different time points during the experiment. Stress of public speaking led to highly significant increases in catecholamine and cortisol concentrations, to subjective discomfort and, most pronounced, to high increases in the number of CD8+ and CD56+ cells. DEX neither influenced baseline levels of mood, catecholamines and cell numbers nor stress induced responses of mood and catecholamines. However, during the whole experiment cortisol concentrations were suppressed in the DEX-condition and the number of CD8+, but not CD56+, cells remained elevated at the end of the session, while in the placebo condition the numbers of these cells were decreased to baseline levels. The data demonstrate that cortisol seems to play an important role in stress induced redistribution patterns of CD8+ but not CD56+ cells. This, however, can be explained by different migration processes between those cells (e.g. different targets of migration) and, therefore, different glucocorticoid influences on target tissues.

The relationship of depression and stressors to immunological assays: a meta-analytic review

This is a broad meta-analysis of the relations of both depression and stressors to immunological assays. The number of study samples (greater than 180) and measures (greater than 40) is much more extensive than any so far. Analyses are done by both fixed and random effects. By a fixed-effects analysis, both major depression and naturally occurring acute stressors are associated with (1) an overall leukocytosis, (2) mild reductions in absolute NK-cell counts and relative T-cell proportions, (3) marginal increases in CD4/CD8 ratios, and (4) moderate decreases in T- and NK-cell function. However, the degree of heterogeneity of the studies' results raises questions about their robustness. Therefore, we also did the first random effects analysis to estimate what is likely to appear in future studies. For depression, the analysis showed the immunological correlates included (1) an overall leukocytosis, manifesting as a relative neutrophilia and lymphoenia; (2) increased CD4/CD8 ratios; (3) increased circulating haptoglobin, PGE(2), and IL-6 levels; (4) reduced NK-cell cytotoxicity; and (5) reduced lymphocyte proliferative response to mitogen. For stressors, the random effects analysis showed that future studies are likely to find the following effects: (1) an overall leukocytosis, manifesting as an absolute lymphocytosis; (2) alterations in cytotoxic lymphocyte levels, CD4/CD8 ratios, and natural killer cell cytotoxicity with the direction of change depending on the chronicity of the stressor; (3) a relative reduction of T-cell levels; (3) increased EBV antibody titers; (4) reduced lymphocyte proliferative response and proportion of IL-2r bearing cells following mitogenic stimulation; and (5) increased leukocyte adhesiveness. The random-effects analysis revealed that for both major depression and naturally occurring stressors the following effects are shared: leukocytosis, increased CD4/CD8 ratios, reduced proliferative response to mitogen, and reduced NK cell cytotoxicity. The implications for these findings for disease susceptibility and the pathophysiology of these conditions is discussed.