Delayed response and lack of habituation in plasma interleukin-6 to acute mental stress in men

When virtual reality becomes psychoneuroendocrine reality: A stress(or) review

This review article was awarded the Dirk Hellhammer award from ISPNE in 2023. It explores the dynamic relationship between stressors and stress from a historical view as well as a vision towards the future of stress research via virtual reality (VR). We introduce the concept of a "syncytium," a permeable boundary that blurs the distinction between stress and stressor, in order to understand why the field of stress biology continues to inadequately measure stress alone as a proxy for the force of external stressors. Using Virtual Reality (VR) as an illustrative example to explicate the black box of stressors, we examine the distinction between 'immersion' and 'presence' as analogous terms for stressor and stress, respectively. We argue that the conventional psychological approaches to stress measurement and appraisal theory unfortunately fall short in quantifying the force of the stressor, leading to reverse causality fallacies. Further, the concept of affordances is introduced as an ecological or holistic tool to measure and design a stressor's force, bridging the gap between the external environment and an individual's physiological response to stress. Affordances also serve to ameliorate shortcomings in stress appraisal by integrating ecological interdependencies. By combining VR and psychobiological measures, this paper aims to unravel the complexity of the stressor-stress syncytium, highlighting the necessity of assessing both the internal and external facets to gain a holistic understanding of stress physiology and shift away from reverse causality reasoning. We find that the utility of VR extends beyond presence to include affordance-based measures of immersion, which can effectively model stressor force. Future research should prioritize the development of tools that can measure both immersion and presence, thereby providing a more comprehensive understanding of how external stressors interact with individual psychological states.

The association between changes in clinical pain severity and IL-6 reactivity among patients undergoing total knee Arthroplasty: The moderating role of change in insomnia

Knee osteoarthritis (KOA) is linked to an enhanced release of interleukin-6 (IL-6). Increased levels of IL-6 are associated with greater pain and insomnia. While total knee arthroplasty (TKA) typically results in the reduction of pain, for a subgroup of patients, pain does not improve. Understanding patients' propensity to upregulate IL-6 may provide insight into variation in the clinical success of TKA for improving pain, and insomnia may play an important modulatory role. We investigated the association between pre- and post-surgical changes in clinical pain and IL-6 reactivity, and whether change in insomnia moderated this association. Patients (n = 39) with KOA came in-person before and 3-months after TKA. At both visits, patients completed validated measures of clinical pain and insomnia, as well as underwent quantitative sensory testing (QST). Blood samples were collected to analyze IL-expression both before and after QST procedures to assess changes in IL-6 in response to QST (IL-6 reactivity). Patients were categorized into two groups based on change in clinical pain from pre- to post-surgery: 1) pain decreased > 2 points (pain improved) and 2) pain did not decrease > 2 points (pain did not improve). Based on this definition, 49 % of patients had improved pain at 3-months. Among patients with improved pain, IL-6 reactivity significantly decreased from pre- to post-surgery, whereas there was no significant change in IL-6 reactivity among those whose pain did not improve. There was also a significant interaction between pain status and change in insomnia, such that among patients whose insomnia decreased over time, improved pain was significantly associated with a reduction in IL-6 reactivity. However, among patients whose insomnia increased over time, pain status and change in IL-6 reactivity were not significantly associated. Our findings suggest that the resolution of clinical pain after TKA may be associated with discernible alterations in pro-inflammatory responses that can be measured under controlled laboratory conditions, and this association may be moderated by perioperative changes in insomnia. Randomized controlled trials which carefully characterize the phenotypic features of patients are needed to understand how and for whom behavioral interventions may be beneficial in modulating inflammation, pain, and insomnia.

Exploration of possible sex bias in acute social stress research: a semi-systematic review

Stress can have a significant impact on the daily lives of individuals and can increase vulnerability to a number of medical conditions. This study aims to estimate the ratio of male to female participants in acute social stress research in healthy individuals. We examined original research articles published over the last 20 years. Each article was screened to determine the total number of female and male participants. We extracted data from 124 articles involving a total of 9539 participants. A total of 4221 (44.2%) participants were female, 5056 (53.0%) were male and 262 (2.7%) were unreported. Articles incorporating only females were significantly underrepresented compared to articles incorporating only males. Forty articles (63.5%) which presented data from both females and males, failed to analyse and interpret the results by sex, a significant methodological limitation. In conclusion, in the literature published over the last 20 years, female participants are significantly underrepresented. In the studies where females are represented, severe methodological limitations are apparent. Researchers should be conscious of sexual dimorphism, menstrual phase and use of hormonal contraception, which may impact the interpretation of their results.

Preoperative depression and anxiety as predictors of postoperative C-reactive protein levels in patients undergoing cardiac surgery: a prospective observational study

AIM OF THE STUDY

In patients undergoing cardiac surgery, preoperative depressive and anxiety symptoms and increased postoperative C-reactive protein (CRP) levels have been associated with adverse outcomes. We tested the hypothesis that preoperative depressive and anxiety symptoms predict elevated in-hospital CRP levels after cardiac surgery.

METHODS

The study participants were 96 consecutive patients (mean age [SD], 67.6 [10.3] years, 78.1% men) from a single cardiac surgery centre who underwent either isolated coronary artery bypass grafting (CABG) (n = 34), isolated valve surgery (n = 29), combined procedures (including different combinations of CABG, valve surgery, aortic surgery, and others) (n = 30), or other cardiac surgical procedures (n = 3). Participants self-rated depressive and anxiety symptoms using the Patient Health Questionnaire (PHQ-9) and the General Anxiety Disorder (GAD-7) questionnaire before undergoing elective surgery. CRP levels were measured every 24 h up to 10 days post-surgery. Linear mixed (random effects) regression analysis examined the association between preoperative depressive and anxiety symptoms and CRP levels over time, adjusting for pre-surgery CRP levels, demographics, cardiovascular risk factors, medications, and surgery-related variables.

RESULTS

Before surgery, 32.2% of patients had clinically relevant depressive symptoms (PHQ-9 score ≥5) and 32.2% of patients had clinically relevant anxiety symptoms (GAD-7 score ≥5). More severe depressive symptoms (estimate [95% CI]: 0.081 [0.023, 0.139], p = 0.007) and more severe anxiety symptoms (0.059 [0.005, 0.113], p = 0.032) predicted CRP levels over 10 days, independent of covariates. Furthermore, CRP levels were higher in patients with than in those without clinically relevant depressive symptoms (0.697 [0.204, 1.191], p = 0.006) and were predicted by both more severe somatic (0.132 [0.035, 0.229], p = 0.008) and cognitive (0.128 [0.014, 0.242], p = 0.029) depressive symptoms.

CONCLUSIONS

Preoperative depressive and anxiety symptoms were independent predictors of elevated CRP levels up to 10 days post-surgery. Such a mechanism may help explain the increased morbidity and mortality risk in patients with depression and anxiety who undergo cardiac surgery.

Neuroimmune mechanisms in fear and panic pathophysiology

Panic disorder (PD) is unique among anxiety disorders in that the emotional symptoms (e.g., fear and anxiety) associated with panic are strongly linked to body sensations indicative of threats to physiological homeostasis. For example, panic attacks often present with feelings of suffocation that evoke hyperventilation, breathlessness, or air hunger. Due to the somatic underpinnings of PD, a major focus has been placed on interoceptive signaling and it is recognized that dysfunctional body-to-brain communication pathways promote the initiation and maintenance of PD symptomatology. While body-to-brain signaling can occur via several pathways, immune and humoral pathways play an important role in communicating bodily physiological state to the brain. Accumulating evidence suggests that neuroimmune mediators play a role in fear and panic-associated disorders, although this has not been systematically investigated. Currently, our understanding of the role of immune mechanisms in the etiology and maintenance of PD remains limited. In the current review, we attempt to summarize findings that support a role of immune dysregulation in PD symptomology. We compile evidence from human studies and panic-relevant rodent paradigms that indicate a role of systemic and brain immune signaling in the regulation of fear and panic-relevant behavior and physiology. Specifically, we discuss how immune signaling can contribute to maladaptive body-to-brain communication and conditioned fear that are relevant to spontaneous and conditioned symptoms of PD and identify putative avenues warranting future investigation.

Stress- and drug-induced neuroimmune signaling as a therapeutic target for comorbid anxiety and substance use disorders

Stress and substance use disorders remain two of the most highly prevalent psychiatric conditions and are often comorbid. While individually these conditions have a debilitating impact on the patient and a high cost to society, the symptomology and treatment outcomes are further exacerbated when they occur together. As such, there are few effective treatment options for these patients, and recent investigation has sought to determine the neural processes underlying the co-occurrence of these disorders to identify novel treatment targets. One such mechanism that has been linked to stress- and addiction-related conditions is neuroimmune signaling. Increases in inflammatory factors across the brain have been heavily implicated in the etiology of these disorders, and this review seeks to determine the nature of this relationship. According to the "dual-hit" hypothesis, also referred to as neuroimmune priming, prior exposure to either stress or drugs of abuse can sensitize the neuroimmune system to be hyperresponsive when exposed to these insults in the future. This review completes an examination of the literature surrounding stress-induced increases in inflammation across clinical and preclinical studies along with a summarization of the evidence regarding drug-induced alterations in inflammatory factors. These changes in neuroimmune profiles are also discussed within the context of their impact on the neural circuitry responsible for stress responsiveness and addictive behaviors. Further, this review explores the connection between neuroimmune signaling and susceptibility to these conditions and highlights the anti-inflammatory pharmacotherapies that may be used for the treatment of stress and substance use disorders.

Leave Me Alone With Your Symptoms! Social Exclusion at the Workplace Mediates the Relationship of Employee's Mental Illness and Sick Leave

Although a substantial part of employees suffers from a mental illness, the work situation of this population still is understudied. Previous research suggests that people with a mental illness experience discrimination in the workplace, which is known to have detrimental effects on health. Building on the stereotype content model and allostatic load theory, the present study investigated whether employees with a mental illness become socially excluded at the workplace and therefore show more days of sick leave. Overall, 86 employees diagnosed with a mental disorder were interviewed and completed online-surveys. Path analyses supported the hypotheses, yielding a serial mediation: The interview-rated severity of the mental disorder had an indirect effect on the days of sick leave, mediated by the symptomatic burden and the social exclusion at the workplace. In the light of the costs associated with absenteeism the present paper highlights the harmfulness of discrimination. Organizations and especially supervisors need to be attentive for signs of exclusion within their teams and try to counteract as early as possible.

Associations between perceived discrimination and immune cell composition in the Jackson Heart Study

African American adults suffer disproportionately from several non-communicable and infectious diseases. Among numerous contributing factors, perceived discrimination is considered a stressor for members of historically marginalized groups that contributes to health risk, although biological pathways are incompletely understood. Previous studies have reported associations between stress and both an up-regulation of non-specific (innate) inflammation and down-regulation of specific (adaptive) immunity. While associations between perceived discrimination and markers of inflammation have been explored, it is unclear if this is part of an overall shift that also includes down-regulated adaptive immunity. Relying on a large cross-section of African American adults (n = 3,319) from the Jackson Heart Study (JHS) in Jackson, Mississippi, we tested whether perceived everyday and lifetime discrimination as well as perceived burden from lifetime discrimination were associated with counts of neutrophils (innate), monocytes (innate), lymphocytes (adaptive), and the neutrophil-to-lymphocyte ratio (NLR), derived from complete white blood cell counts with differential. In addition, DNA methylation (DNAm) was measured on the EPIC array in a sub-sample (n = 1,023) of participants, allowing estimation of CD4T, CD8T and B lymphocyte proportions. Unexpectedly, high lifetime discrimination compared to low was significantly associated with lower neutrophils (b : -0.14, [95% CI: -0.24, -0.04]) and a lower NLR (b : -0.15, [95% CI: -0.25, -0.05]) after controlling for confounders. However, high perceived burden from lifetime discrimination was significantly associated with higher neutrophils (b : 0.17, [95% CI: 0.05, 0.30]) and a higher NLR (b : 0.16, [95% CI: 0.03, 0.29]). High perceived burden was also associated with lower lymphocytes among older men, which our analysis suggested might have been attributable to differences in CD4T cells. These findings highlight immune function as a potentially important pathway linking perceived discrimination to health outcomes.

Stressed in afterthought: Neuroendocrine effects of social self-threat during physical effort are counteracted by performance feedback after stress exposure

Social self-threat during physical stress, such as exposure to the cold pressor test and isometric handgrip test, has been shown to induce activation of the HPA axis, in addition to autonomic responses. However, previous research has suggested that dysfunctional post-event processing may play a major role in neuroendocrine reactivity at initial as well as subsequent social stress exposure. In the present study, we investigated how the interplay of context (i.e. performance feedback) with state (i.e., self-esteem) as well as trait-like factors (i.e., ruminative tendencies) affects stress responses to repeated, short bouts of physical activity. On two sessions, 1 week apart, 53 participants (27 women) performed an isometric handgrip task for 3 min, during which they were exposed to social-evaluative threat. In addition, participants received fake feedback on their performance immediately after the task, labeling it as either 'above' (positive) or 'below average' (negative). In addition to neuroendocrine (cortisol), cardiovascular (heart rate, blood pressure) and subjective stress reactivity, performance-related and social dimensions of state self-esteem were assessed before and after stress induction. Substantial increases in cardiovascular parameters were found on both days, regardless of feedback condition. However, positive feedback led to significantly diminished neuroendocrine responses on day 1, whereas baseline cortisol on session 2 was significantly higher in the negative feedback group. Conversely, social self-esteem decreased after stress induction on both days only for participants who had received negative feedback. Changes in self-esteem reported on day 1 were associated with increased baseline cortisol at the second session, while interindividual differences in self-reported (trait) rumination were associated with cortisol reactivity at session 1. Taken together, the results suggest that effects of social evaluation during short periods of physical stress rely on post-event processing and might be counteracted by positive appraisal directly after stress exposure. Post-hoc framing (in terms of success vs. failure) may predict subsequent stress-related hormonal effects better than task demands per se, which should be considered as a potential moderator in future acute stress research, but might also be relevant to many practical applications in fields ranging from sports/performance to health psychology.

Increased Concentrations of Circulating Interleukins following Non-Invasive Vagus Nerve Stimulation: Results from a Randomized, Sham-Controlled, Crossover Study in Healthy Subjects

OBJECTIVE

The vagus nerve constitutes the main component of the parasympathetic nervous system and plays an important role in the regulation of neuro-immune responses. Invasive stimulation of the vagus nerve produces anti-inflammatory effects; however, data on humoral immune responses of transcutaneous vagus nerve stimulation (tVNS) are rare. Therefore, the present study investigated changes in serum cytokine concentrations of interleukin-1β (IL-1β), IL-6, IL-8, and tumor necrosis factor α (TNFα) following a short-term, non-invasive stimulation of the vagus nerve.

METHODS

Whole blood samples were collected before and after a short-lived application of active tVNS at the inner tragus as well as sham stimulation of the earlobe. Cytokine serum concentrations were determined in two healthy cohorts of younger (n = 20) and older participants (n = 19). Differences between active and sham conditions were analyzed using linear mixed models and post hoc F tests after applying Yeo-Johnson power transformations. This trial was part of a larger study registered on ClinicalTrials.gov (NCT05007743).

RESULTS

In the young cohort, IL-6 and IL-1β concentrations were significantly increased after active stimulation, whereas they were slightly decreased after sham stimulation (IL-6: p = 0.012; IL-1β: p = 0.012). Likewise, in the older cohort, IL-1β and IL-8 concentrations were significantly elevated after active stimulation and reduced after sham application (IL-8: p = 0.007; IL-1β: p = 0.001). In contrast, circulating TNFα concentrations did not change significantly in either group.

CONCLUSION

Our results show that active tVNS led to an immediate increase in the serum concentrations of certain pro-inflammatory cytokines such as IL-1β, IL-6, and/or IL-8 in two independent cohorts of healthy study participants.

Systemic inflammation as a driver of health disparities among sexually-diverse and gender-diverse individuals

Sexually-diverse individuals (those who seek sexual or romantic relationships with the same and/or multiple genders) and gender-diverse individuals (those whose gender identity and/or expression differs from their birth-assigned sex/gender) have disproportionately high physical health problems, but the underlying biological causes for these health disparities remain unclear. Building on the minority stress model linking social stigmatization to health outcomes, we argue that systemic inflammation (the body's primary response to both physical and psychological threats, indicated by inflammatory markers such as C-reactive protein and proinflammatory cytokines) is a primary biobehavioral pathway linking sexual and gender stigma to physical health outcomes. Expectations and experiences of social threat (i.e., rejection, shame, and isolation) are widespread and chronic among sexually-diverse and gender-diverse individuals, and social threats are particularly potent drivers of inflammation. We review research suggesting that framing "minority stress" in terms of social safety versus threat, and attending specifically to the inflammatory consequences of these experiences, can advance our understanding of the biobehavioral consequences of sexual and gender stigma and can promote the development of health promoting interventions for this population.

The repeated Montreal Imaging Stress Test (rMIST): Testing habituation, sensitization, and anticipation effects to repeated stress induction

BACKGROUND

A psychosocial task that can induce comparable levels of stress repeatedly is fundamental to effectively study changes in stress reactivity over time or as a result of an intervention. However, existing tasks have struggled to provide consistent stress responses across repeated trials.

AIM

The goal was to assess the efficacy of two different designs of the repeated Montreal Imaging Stress Test (rMIST) in reproducing the same pattern of reactivity over two separate sessions.

METHODS

In two different studies, stress was induced using the rMIST on two separate sessions, one week apart. Each study used a different task design. In the first study (53 participants [45 women]; mean age=24.16 [SD=3.29]), the rMIST consisted of a single-longer stress exposure, while the second study (30 participants [27 women]; mean age=21.81 [SD=2.09]) consisted of several shorter stress exposures per session. Self-reported (i.e perceived stress [PS] and negative affect [NA]), physiological (i.e heart rate [HR], root mean square of successive differences [RMSSD]) and hormonal (i.e. salivary cortisol) measures of stress were used.

RESULTS

Stress reactivity was comparable across the two repeated stress sessions in both studies. However, baseline HR in the second session increased relative to the first session in the first study, and there was no cortisol response. Additionally, there was a decrease in HR and HRV reactivity within the session on the second study, suggesting a habituation effect not between but within the session itself.

CONCLUSION

The rMIST overcomes some of the challenges associated with repeated stress induction. However, an anticipation effect and a lack of cortisol response indicate that further adjustments to the task are necessary. Finally, task design is important for repeated stress reactivity.

[Accelerated telomere erosion in schizophrenia: A literature review]

Schizophrenia is associated with a weighted average of 14.5 years of potential life lost according to a recent meta-analysis. This is partly explained by high rates of suicide and a high prevalence of non-psychiatric comorbidity (cardiovascular diseases, diabetes, cancers…). However, all these causes could not fully explain the loss of life expectancy in people suffering from schizophrenia. Life expectancy has been strongly correlated with telomere length (TL). Telomeres are noncoding structures consisting of DNA TTAGGG tandem repeats and associated proteins located at the end of the chromosomes. Their role is to help preserve genome stability by protecting chromosomal ends from the loss of genetic material. The progressive loss of telomeric material during cell divisions has led researchers to consider telomeres as molecular clocks that measure the number of divisions left until cellular death. The fact that both shorter telomeres and schizophrenia have been associated with a decrease in life expectancy has fueled the interest in the study of TL in schizophrenia. In this article, after a detailed review of the literature on the relationships between telomere length and schizophrenia, we discuss the different pathophysiological mechanisms which might explain this association. Based on this analysis, in the last part of the article we discuss potential research, therapeutic and prevention prospects. To date, the majority of the studies and meta-analyses found a decrease in TL in subjects with schizophrenia compared to control subjects. Conversely, all the studies exploring the TL in subjects suffering from first episode psychosis (FEP) have shown no significant difference from TL in control subjects. This suggests that excessive shortening of telomeres occurs during the course of the disease, thus it seems more probable that schizophrenia (or processes associated with it) affects TL rather than telomere erosion being a cause of the disorder. Several pathophysiological, non-mutually exclusive mechanisms have been proposed to explain the observed data. A first hypothesis to explain the acceleration of the physiological process of telomere erosion in schizophrenia is the activation of inflammation processes and oxidative stress as a consequence of schizophrenia per se. However, it seems more probable that reduced TL may be a result of cumulative exposure to chronic stress related to schizophrenia. Indeed, in healthy individuals a growing body of evidence has linked chronic stress to accelerated shortening of TL. This might explain why telomere erosion is too small to be detected in FEP patients who are younger and have a shorter duration of illness than subjects with schizophrenia. Based on these both explanations, telomere alterations may be considered as a biomarker of illness progression and might be useful for illness staging. Identifying processes associated with TL reduction might improve our understanding of the increased mortality and morbidity in schizophrenia, improve reliability of diagnosis, and hopefully suggest means for prevention and/or treatment. Treatments that prevent exposure and/or vulnerability to stressful life events that ameliorate schizophrenia may also prevent or decelerate telomere erosion. In this perspective, engaging subjects suffering from schizophrenia in a healthy diet and regular activity could be both promising strategies to protect telomere maintenance and improve health span at old age. In addition, the inflammatory process and oxidative stress involved in the physiopathology in at least a subgroup of subjects with schizophrenia could also be responsible for telomere erosion. Thus, an efficient anti-inflammatory therapeutic approach that targets these specific pathways could be of interest in this subgroup to limit telomere erosion. Mindfulness-based stress reduction (MBSR) therapies have been shown to reduce telomere erosion by increasing telomerase activity, although these psychological therapies should be used carefully in psychosis. Finally, advancing our understanding of the relationship between stress, inflammation and TL is of great interest for psychiatric research and for understanding stress effects in this population.

Evaluation of a remote, internet-delivered version of the Trier Social Stress Test

The Trier Social Stress Test (TSST) is a widely used, reliable, and ecologically valid method for inducing acute stress under controlled conditions. Traditionally, the TSST is administered with staff physically present with participants, which limits the participant populations that can be exposed to the TSST. We describe an adaptation of the TSST to remote, online delivery over video-conferencing, which we call the internet-delivered Trier Social Stress Test (iTSST). This adaption has participants use wearable, self-administered ECG monitors received and returned via mail. Fifty participants were recruited to take part in a pilot study evaluating stress-reduction interventions and completed the iTSST at two occasions separated by approximately 12 weeks. Perceived stress and heart rate variability (HRV) were measured during both administrations of the iTSST. Forty-one participants completed both assessments and were included in the set of analyses. Both administrations were characterized by an increase in self-reported stress and reduction in self-reported relaxation from the resting phase to the speech task, which returned to baseline during recovery. In terms of HRV, we observed a significant parasympathetic response to the iTSST in 90% of participants, evidenced by a decrease in RMSSD and increase in heart rate from resting to the speech task, which recovered during the recovery phase. In terms of repeatability, there was little evidence of habituation and the iTSST elicited a stress response during both the initial administration and the 12-week follow-up. While the utility is limited by the lack of a measure of sympathetic and HPA-axis activity, the iTSST represents a promising research tool when physically interacting with participants is not feasible.

Could Physical Activity Have any Role in Cardiovascular Disease Prevention in Prisoners? A Systematic Review

More than 10.74 million people are currently held in penal institutions worldwide. Moreover, there is also evidence that the percentage of elder and female prisoners has been consistently growing. Cardiovascular diseases are the leading cause of death worldwide. Exercise training and physical activity help to prevent both primary and secondary cardiovascular events. Data on the influence of physical activity on the well-being in prison population is scarce. Here, we discussed, in a systematic review, the general health conditions and the cardiovascular risk profile in the prisoners compared to the general population and evaluated whether or not exercise could be a valuable tool in preventing these diseases in inmates. We performed a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement: 769 were initially identified, and a total of 24 studies were finally included. Nine studies evaluated the health conditions in prisoners, five studies evaluated the incidence of cardiovascular disease (CVD) and coronary heart disease (CHD) in the prison population, and 10 studies evaluated the feasibility and the effectiveness of exercise programs in prisoners. Sports-educational programs can benefit prison inmates. It appears that supervised exercise training is an effective coping strategy to deal with incarceration. Moreover, it seems the sports programs might be a useful tool in improving physical and mental health of prisoners as well as in decreasing cardiovascular risk factors.

Impact of Acute and Chronic Stress on Thrombosis in Healthy Individuals and Cardiovascular Disease Patients

Psychological stress induces different alterations in the organism in order to maintain homeostasis, including changes in hematopoiesis and hemostasis. In particular, stress-induced hyper activation of the autonomic nervous system and hypothalamic–pituitary–adrenal axis can trigger cellular and molecular alterations in platelets, coagulation factors, endothelial function, redox balance, and sterile inflammatory response. For this reason, mental stress is reported to enhance the risk of cardiovascular disease (CVD). However, contrasting results are often found in the literature considering differences in the response to acute or chronic stress and the health condition of the population analyzed. Since thrombosis is the most common underlying pathology of CVDs, the comprehension of the mechanisms at the basis of the association between stress and this pathology is highly valuable. The aim of this work is to give a comprehensive review of the studies focused on the role of acute and chronic stress in both healthy individuals and CVD patients, focusing on the cellular and molecular mechanisms underlying the relationship between stress and thrombosis.

IL-6 Response to Psychosocial Stress Predicts 12-month Changes in Cardiometabolic Biomarkers in Perimenopausal Women

OBJECTIVE

Cardiometabolic diseases are the number one cause of mortality, accounting for over one third of all deaths in the United States. Cardiometabolic risk further increases with psychosocial stress exposure and during menopausal transition in women. Because disease risk and stress burden are associated with aberrant immune signaling, we hypothesized that responses of interleukin-6 (IL-6) to psychosocial stress may predict longitudinal cardiometabolic outcomes in perimenopausal women.

METHODS

We conducted post hoc analyses in 151 perimenopausal or early postmenopausal women participants in a previously completed study. At study onset, participants underwent the Trier Social Stress Test (TSST), and plasma IL-6 was measured repeatedly before and during the 1 hour post-TSST. Subsequently, participants were randomly assigned to either hormonal treatment (HT) or placebo and followed for 12 months to determine longitudinal changes in cardiometabolic biomarkers.

RESULTS

Greater IL-6 reactivity to stress, measured with baseline-adjusted area under the curve, predicted 12-month decrease in flow-mediated dilatation of the brachial artery (P = 0.0005), a measure of endothelial-dependent vascular function, but not in endothelial-independent function measured with nitroglycerin-mediated dilatation (P = 0.17). Greater baseline IL-6 levels predicted 12-month increase in insulin resistance based on the homeostatic model assessment of insulin resistance score (P = 0.0045) and in the number of criteria met for metabolic syndrome (P = 0.0008). These predictions were not moderated by HT.

CONCLUSIONS

Greater baseline IL-6 levels as well as its reactivity to stress may predict worsening in distinct cardiometabolic biomarkers as women transition to menopause. Interleukin-6 reactivity predicts decline in endothelial-dependent vascular function, whereas baseline IL-6 presages accumulation of metabolic risk.

Evaluation of the Effectiveness of One- and Multi-Session Exposure-Based Treatments in Reducing Biological and Psychological Responses to Rat Phobia Among Students

BACKGROUND

Animal phobia is one of the most common forms of specific phobias. This anxiety disorder challenges the medical student working with animal models. Regarding this, the present study was conducted to investigate the effectiveness of one- and multi-session cognitive exposure-based treatments in students with rat phobia.

METHODS

For the purpose of the study, a total of 40 female students with rat phobia were allocated into two groups of one- and multi-session cognitive exposure-based treatments. The data were collected using psychological measures, including state anxiety, rat phobia, and disgust questionnaires, which were completed in three stages, including the baseline, pre-treatment, and post-treatment. The gene expression levels of pro-inflammatory cytokines (ie, interleukin-1 [IL-1], nuclear factor-kappaB [NF-κB], and tumor necrosis factor-alpha [TNFα]) associated with acute stress, as well as the serum levels of IL-6 and cortisol, were determined using reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) methods. This study was registered at the Iranian Registry of Clinical Trials (IRCT20171123037602N1).

RESULTS

According to the results, both treatments yielded a significant reduction in almost all psychological measures and biological variables, except for IL-6. Rat phobia was the only variable that showed a statistically greater reduction in the multi-session treatment group. Furthermore, rat phobia and disgust reduction were maintained in both groups to the same extent during follow-up.

CONCLUSION

The findings of the present study were indicative of the incidence of habituation in psychological and biological factors following exposure therapy. Both one- and multi-session treatments reduced the factors associated with rat phobia almost to the same degree. As a result of the high levels of disgust, anxiety-related biological factors remained high in four students despite observing a significant reduction in their fear. This led to passive avoidance in this group. The OST enabled the students to handle rats in less than half a day. Accordingly, it could be applied as a half-day workshop for students in medical universities to avoid the incidence of associated anxiety-related disorders in this group.

Temperament traits moderate the relationship between Childhood Trauma and Interleukin 1β profile in young adults

Early life stressors, such as childhood trauma, have been associated to alterations in immune response that can last until adulthood. In this context, interleukin 1β (IL-1β) emerges as a pro-inflammatory cytokine with a pivotal role. Also, considering the temperament differences in stress susceptibility, and even immune dysfunction, studies investigating the complex interaction between these factors are scarce. Thus, the aim of the present study was to evaluate the moderating role of temperament traits in the relationship between childhood trauma and serum IL-1β levels. This cross-sectional study consisted of 325 individuals, men and women, aged 18-35, enrolled from a population-based study in the city of Pelotas, Southern Brazil. Our main results indicate that higher serum levels of IL-1β were associated with trauma severity (p < 0.01), and the variance of anger could explain 29% of IL-1β increase in individuals who suffered severe trauma (p < 0.05). The effect of anger was considerably stronger in men than in women (46% and 25%, respectively). Moreover, the variance of sensitivity also explained 15% of IL-1β increase (p < 0.05) as well as the variance of volition explained 11% of IL-1β decrease (p < 0.05) in individuals who suffered severe trauma in the general population. Our results indicate that emotional individual differences can moderate the impact of childhood trauma on low-grade inflammation in young adults.

Sex Differences in Interleukin-6 Responses Over Time Following Laboratory Pain Testing Among Patients With Knee Osteoarthritis

Epidemiological studies suggest that women are not only at a higher risk for developing knee osteoarthritis (KOA), but also report greater symptom severity compared to men. One potential underlying mechanism of these sex differences may be exaggerated inflammatory responses to pain among women compared to men. The present study examined sex differences in interleukin-6 (IL-6) response over time following experimental pain testing. We hypothesized that women, when compared to men, would show greater IL-6 reactivity when exposed to acute pain in a human laboratory setting. Eighty-four participants (36 men and 48 women) with KOA scheduled for total knee arthroplasty underwent a quantitative sensory testing (QST) battery. A total of seven IL-6 measurements were taken, twice at baseline, once immediately after QST, and every 30 minutes up to 2 hours after QST. Consistent with our hypothesis, women, when compared to men, showed accelerated increases in IL-6 levels following laboratory-evoked pain, even after controlling for body mass index, marital status, clinical pain, evoked pain sensitivity, and situational pain catastrophizing. Given that KOA is a chronic condition, and individuals with KOA frequently experience pain, these sex differences in IL-6 reactivity may contribute to the maintenance and/or exacerbation of KOA symptoms. PERSPECTIVES: The present study demonstrates that women, when compared to men, exhibit greater IL-6 reactivity after exposure to laboratory-evoked pain. Such sex differences may explain the mechanisms underlying women's higher chronic pain risk and pain perception, as well as provide further insight in developing personalized pain interventions.

Childhood Physical Neglect Is Associated With Exaggerated Systemic and Intracellular Inflammatory Responses to Repeated Psychosocial Stress in Adulthood

Experiences of child maltreatment are associated with a host of adverse mental and physical health outcomes in adulthood. Altered reactivity to psychosocial stress exposure may partially explain known associations between early experiences of maltreatment and later life health. The present study focuses on examining whether experiences of child maltreatment are associated with physiological reactions to initial and repeated psychosocial stress in adulthood. To this end, 44 healthy adults (52% male, aged 18-65) completed the Childhood Trauma Questionnaire to provide information about exposure to child maltreatment and completed the Trier Social Stress Test (TSST) on 2 consecutive days. Peripheral blood was collected prior to as well as 30 and 120 min following the TSST on each day. Plasma Interleukin-6 (IL-6) and gene expression of IL-6, IL-1β, nuclear factor-kB (NF-kB), and inhibitor of kB (IkB) were measured from each blood sample. Total CTQ scores were unrelated to plasma IL-6 and gene expression (ps > .10) but a history of childhood physical neglect was associated with increased interleukin-1β (β =.35; p =.02; R² =.19) and nuclear factor-kB (β =.30; p =.046; R² =.13) expression following initial stress. Following repeated exposure to the TSST, childhood physical neglect was associated with increased plasma IL-6 reactivity (β =.34; p =.02; R² =.16) and increased expression of nuclear factor-kB (β =.31; p =.04; R² =.08). Finally, childhood physical neglect was associated with decreased habituation following repeated exposure to the TSST. Other CTQ subscales were not related to plasma IL-6 and gene expression when considered individually. Results from this study are suggestive of a unique effect of childhood physical neglect on the physiological stress response following initial and repeated exposure to a common psychosocial stressor. This provides important directions for future research because the effect of childhood physical neglect on long-term neglect are not well understood and in need of further investigation.

Inflammatory Biomarkers are Correlated with Some Forms of Regressive Autism Spectrum Disorder

Background: Several studies have tried to investigate the role of inflammatory biomarkers in Autism Spectrum Disorder (ASD), and their correlations with clinical phenotypes. Despite the growing research in this topic, existing data are mostly contradictory. Methods: Eighty-five ASD preschoolers were assessed for developmental level, adaptive functioning, gastrointestinal (GI), socio-communicative and psychopathological symptoms. Plasma levels of leptin, resistin, plasminogen activator inhibitor-1 (PAI-1), macrophage chemoattractant protein-1 (CCL2), tumor necrosis factor-alfa (TNF-α), and interleukin-6 (IL-6) were correlated with clinical scores and were compared among different ASD subgroups according to the presence or absence of: (i) GI symptoms, (ii) regressive onset of autism. Results: Proinflammatory cytokines (TNF-α, IL-6 and CCL2) were lower than those reported in previous studies in children with systemic inflammatory conditions. GI symptoms were not correlated with levels of inflammatory biomarkers except for resistin that was lower in ASD-GI children (p = 0.032). Resistin and PAI-1 levels were significantly higher in the group with “regression plus a developmental delay” onset (Reg+DD group) compared to groups without regression or with regression without a developmental delay (p < 0.01 for all). Conclusions: Our results did not highlight the presence of any systemic inflammatory state in ASD subjects neither disentangling children with/without GI symptoms. The Reg + DD group significantly differed from others in some plasmatic values, but these differences failed to discriminate the subgroups as possible distinct ASD endo-phenotypes.

Objectively Measured Social Integration Is Associated With an Immune Risk Phenotype Following Marital Separation

Background

Close relationships play an integral role in human development, and robust evidence links marital separation and divorce to poor health outcomes. Social integration may play a key role in this association. In many ways, the study of marital separation and divorce provides an ideal model system for a more complete understanding of the association between life stress and physical health.

Purpose

The current study investigated associations among objectively measured social integration, psychological distress, and biomarkers of immune health in recently separated adults (N = 49).

Methods

We collected four measures of immune functioning-interleukin-6, C-reactive protein, and antibody titers to latent cytomegalovirus and Epstein-Barr virus-that were combined to yield a viral-Immune Risk Profile. To assess how variability in social integration is associated with immunological correlates following the end of a marriage, we incorporated observational ecological momentary assessment data using a novel methodology (the Electronically Activated Recorder).

Results

We found that objectively measured social behaviors are associated with concurrent viral-Immune Risk Profile scores over and above the effects of psychological distress and that psychological distress may be linked to biomarkers of immune health through social integration.

Conclusions

This research expands current knowledge of biomarkers of immune health after divorce and separation and includes a new methodology for objective measures of social engagement.

The Relationship Between Circulating Interleukin-6 Levels and Future Health Service Use in Dementia Caregivers

OBJECTIVE

Older adults are among the most frequent users of emergency departments (EDs). Nonspecific symptoms, such as fatigue and widespread pain, are among the most common symptoms in patients admitted at the ED. Interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) are inflammation biomarkers associated with chronic stress (i.e., dementia caregiving) and nonspecific symptoms. This study aimed to determine whether IL-6 and TNF-α were prospectively associated with ED risk in dementia caregivers (CGs).

METHODS

Participants were 85 dementia CGs, who reported during three assessments (3, 9, and 15 months after enrollment) if they had visited an ED for any reason. Cox proportional hazards models were used to examine the relations between resting circulating levels of IL-6 and TNF-α obtained at enrollment and subsequent risk for an ED visit, adjusting for age, sex, use of ED 1 month before enrollment, physical and mental health well-being, body mass index, and CG demands.

RESULTS

(log) IL-6 significantly predicted ED visits during the 15-month follow-up (B = 1.96, SE = 0.82, p = .017). For every (log) picogram per milliliter increase in IL-6, the risk of visiting an ED was 7.10 times greater. TNF-α was not associated with subsequent ED visits. Exploratory analyses suggested that CGs with levels of IL-6 above the 80th percentile and experiencing high CG demands were at highest risk of an ED visit.

CONCLUSIONS

IL-6 levels and CG demands may be useful for predicting vulnerability for future ED visits. Although further studies should be conducted to replicate and extend these findings, interventions that successfully modify inflammation markers, including the underlying pathophysiology related to stress and/or comorbid illnesses, may be useful in preventing costly and detrimental outcomes in this population.

Stress and inflammation - The need to address the gap in the transition between acute and chronic stress effects

Stress responses help us navigate our environment and respond appropriately to threats. Stress systems communicate threats to the entire organism, and as such, also stimulate inflammatory mechanisms. This modulation might serve protective functions in the short term, but sustained low-grade inflammation has severe long-term health consequences. While we have reached a reasonable level of understanding of acute, as well as chronic stress effects on inflammatory mechanisms, there is a significant gap in our understanding of the transitional phase between acute and chronic stress. The purpose of this review is to first summarize current knowledge of our understanding of acute stress effects on inflammation, as well as of chronic stress effects on inflammation, and to then analyze the state of knowledge about the transitional phase between acute and chronic stress. Research discussed here shows that we are beginning to understand the early phase of repeated acute stress, but lack information on longer term exposure to repeated acute stress experiences. More research is needed to bridge this important gap und our conceptualization and understanding of the stress and health relationship.

Investigating the Optimal Baseline Positioning to Maximize Cognitive Experimental Outcome

In emotional and cognitive research, the baseline is commonly used for standardization purposes in order to have a reference for the identification of the activation. Since no previous studies have investigated which moment of the experiment could be considered optimal for baseline evaluation, we designed an experimental protocol to analyze which time interval could be considered more effective in highlighting differences between the baseline state and the cognitive effort exhibited during tasks (specifically, reaction and working memory tasks). Several indexes were extracted from EEG signals during the visualization of the considered baseline stimuli and the execution of tasks. From our results, as regards to the considered Global Field Power (GFP) indexes (Attention and Memorization indexes), the last baseline stimulus seems to be the best one to highlight the difference in cognitive workload between the individual baseline condition and the two cognitive tasks. Instead, in terms of Engagement index (EI), the difference between Reaction Task (RT) and the individual baseline condition seems to be best highlighted by the relaxing video right after performed tasks. In conclusion, the best baseline position to maximize the differences in cognitive workload may vary among the considered indexes because of confounding effects and individual differences, but further analyses are required to validate this result.

Old Friends, immunoregulation, and stress resilience

There is a considerable body of evidence indicating that chronic adverse experience, especially chronic psychosocial stress/trauma, represents a major risk factor for the development of many somatic and affective disorders, including inflammatory bowel disease (IBD) and posttraumatic stress disorder (PTSD). However, the mechanisms underlying the development of chronic stress-associated disorders are still in large part unknown, and current treatment and prevention strategies lack efficacy and reliability. A greater understanding of mechanisms involved in the development and persistence of chronic stress-induced disorders may lead to novel approaches to prevention and treatment of these disorders. In this review, we provide evidence indicating that increases in immune (re-)activity and inflammation, potentially promoted by a reduced exposure to immunoregulatory microorganisms ("Old Friends") in today's modern society, may be causal factors in mediating the vulnerability to development and persistence of stress-related pathologies. Moreover, we discuss strategies to increase immunoregulatory processes and attenuate inflammation, as for instance contact with immunoregulatory Old Friends, which appears to be a promising strategy to promote stress resilience and to prevent/treat chronic stress-related disorders.

Associations of Personality Traits With Chronic Low-Grade Inflammation in a Swiss Community Sample

Objective: Among the major dimensions of personality, high Neuroticism and low Conscientiousness have frequently been linked to worse health-related behaviors and poor health outcomes. However, studies on the association between personality traits and biomarkers of chronic low-grade inflammation reflecting increased morbidity and mortality risk are sparse; therefore, the aim of this study was to explore this association. Methods: A population-based Swiss sample of 2,182 persons (40-82 years, 42% men) completed a comprehensive personality questionnaire (NEO Five-Factor Inventory-Revised). Circulating levels of inflammatory markers, including C-reactive protein, interleukin (IL)-1β, IL-6, tumor necrosis factor-α, and levels of the "cardioprotective" adipo(cyto)kine adiponectin were also determined. Analyses controlled for sociodemographic factors, traditional cardiovascular risk factors and lifetime psychiatric disorders using a validated semi-structured psychiatric interview. The role of gender as a moderator of the personality-inflammation link was additionally explored. Results: Controlling for all covariates, higher Extraversion (β = 0.092, 95%CI 0.004-0.180) was positively associated with higher IL-6 levels, and higher Conscientiousness (β = -0.095, 95%CI -0.180-[-0.009]) were significantly associated with lower IL-6 levels (all p-values < 0.05). Neuroticism and Agreeableness showed no significant association with any inflammatory biomarker. The associations between personality traits and inflammatory markers were not moderated by gender. Conclusions: Conscientiousness seems to be inversely related to chronic low-grade inflammation as measured by IL-6 levels, compatible with protection from the cardiovascular risk. The opposite may apply to Extraversion. Further research is needed to better understand the underlying mechanisms and their impact for health outcomes in the community.

Biopsychosocial approach to understanding resilience: Stress habituation and where to intervene

BACKGROUND

Resilience in the face of adversity is a human experience that leads to better health, both mentally and physically. We briefly review its historical origins rooted in ecological biology and its adoption into health care. Resilience is the common response to adversity or potential traumatic events. Individual differences in emotion regulation and coping skills as well as social capital and one's physical environment influence a person's ability to achieve resilience.

PROPOSED MECHANISM

One potential biopsychosocial measure of resilience includes stress habituation to repeated stress as demonstrated in the laboratory, possibly providing a tool to observe mastery of resilience training in the clinic. Evidence-based interventions at the individual and small group level (eg, family, classroom) have successfully shown development of resilient behaviours and improved mental and physical health outcomes. However, the role of social context and public policy clearly influence an individual's ability to be resilient.

CONCLUSIONS

Despite the current limited evidence of the effectiveness of resilience building interventions, clinicians, researchers, and other health care professions have an obligation to become advocates for laws and policies that support the most vulnerable, and least resilient, in our society to attain resilience for their health. This salutary effect will enable them to become socially as well as economically productive members of the community at large. It is not possible to remove stress or adversity from life, but we can influence the development of regulatory flexibility and decrease the sociocultural factors linked to the nonresilient experience, thus mitigating adversity's long-term effects on health.

Exploring the multidimensional complex systems structure of the stress response and its relation to health and sleep outcomes

To gain a comprehensive understanding of the multidimensional complex systems structure of the stress response and related health outcomes, we utilized network analysis in a sample of 328 healthy participants in two steps. In a first step, we focused on associations between measures of basal hypothalamic-pituitary-adrenal axis functioning and subjective stress perceptions. In a second step, we linked these diverse stress-related measures to biomarkers and self-reports of health and sleep. Overall, measures clustered depending on their method of assessment, with high correlations between different saliva-based indices of diurnal cortisol regulation, between cortisol and cortisone levels in hair, between different biological health indicators (systemic inflammatory activity and body mass index), between state (experience sampling) and trait (questionnaire-based) self-reports of stress and wellbeing, and between different self-reports of sleep. Bridges between clusters suggested that if individuals perceive stress throughout their daily lives this is reflected in their total salivary cortisol output possibly contributing to long-term cortisol accumulation in hair. Likewise, earlier awakening time may contribute to cortisol accumulation in hair via an influence on awakening cortisol processes. Our results show that while meaningful connections between measures exist, stress is a highly complex construct composed of numerous aspects. We argue that network analysis is an integrative statistical approach to address the multidimensionality of the stress response and its effects on the brain and body. This may help uncover pathways to stress-related disease and serve to identify starting points for prevention and therapeutic intervention.

Gender differences in longitudinal relationships between depression and anxiety symptoms and inflammation in the health and retirement study

Depression and anxiety have been linked to elevated inflammation in cross-sectional and longitudinal studies. Yet, in terms of longitudinal studies, findings are inconsistent regarding whether depression predicts worsening inflammation or vice versa, and anxiety has been infrequently examined. Further, we know little about longitudinal relationships between inflammation and specific symptom profiles of depression and anxiety. The current study examined longitudinal associations between depression and anxiety symptoms and inflammation in 13,775 people (59% women, average age = 67) participating in the Health and Retirement Study - a population-based study focused on older adults. High sensitivity C-reactive protein and depression and anxiety symptoms were measured at two time-points separated by four years. We used cross-lagged panel models to examine bidirectional relationships, and tested interactions with gender. We found that depressive symptoms predicted increasing inflammation for men, but not for women, and inflammation predicted worsening depression for women, but not for men. These gender differences were driven by somatic symptoms. Specifically, somatic symptoms predicted increasing inflammation for men only and were predicted by inflammation for women only. Regardless of gender, inflammation predicted worsening dysphoric symptoms of depression, and lack of positive affect predicted increasing inflammation over time. Anxiety was not associated with inflammation longitudinally. These findings indicate bidirectional relationships between depressive symptoms and inflammation, but not between anxiety symptoms and inflammation, and that the direction of these effects may differ by gender and type of depressive symptom.

Timing matters: the interval between acute stressors within chronic mild stress modifies behavioral and physiologic stress responses in male rats

Chronic mild stress can lead to negative health outcomes. Frequency, duration, and intensity of acute stressors can affect health-related processes. We tested whether the temporal pattern of daily acute stressors (clustered or dispersed across the day) affects depression-related physiology. We used a rodent model to keep stressor frequency, duration, and intensity constant, and experimentally manipulated the temporal pattern of acute stressors delivered during the active phase of the day. Adult male Sprague-Dawley rats were exposed to one of three chronic mild stress groups: Clustered: stressors that occurred within 1 hour of each other (n = 21), Dispersed: stressors that were spread out across the active phase (n = 21), and Control: no stressors presented (n = 21). Acute mild stressors included noise, strobe lights, novel cage, cage tilt, wet bedding, and water immersion. Depression-related outcomes included: sucrose preference, body weight, circulating glucocorticoid (corticosterone) concentration after a novel acute stressor and during basal morning and evening times, and endotoxin-induced circulating interleukin-6 concentrations. Compared to control rats, those in the Clustered group gained less weight, consumed less sucrose, had a blunted acute corticosterone response, and an accentuated acute interleukin-6 response. Rats in the Dispersed group had an attenuated corticosterone decline during the active period and after an acute stressor compared to the Control group. During a chronic mild stress experience, the temporal distribution of daily acute stressors affected health-related physiologic processes. Regular exposure to daily stressors in rapid succession may predict more depression-related symptoms, whereas exposure to stressors dispersed throughout the day may predict diminished glucocorticoid negative feedback.

The very low-frequency band of heart rate variability represents the slow recovery component after a mental stress task

The very low-frequency (VLF) band of heart rate variability (HRV) has different characteristics compared with other HRV components. Here we investigated differences in HRV changes after a mental stress task. After the task, the high-frequency (HF) band and ratio of high- to low-frequency bands (LF/HF) immediately returned to baseline. We evaluated the characteristics of VLF band changes after a mental stress task. We hypothesized that the VLF band decreases during the Stroop color word task and there would be a delayed recovery for 2 h after the task (i.e., the VLF change would exhibit a “slow recovery”).

Nineteen healthy, young subjects were instructed to rest for 10 min, followed by a Stroop color word task for 20 min. After the task, the subjects were instructed to rest for 120 min. For all subjects, R-R interval data were collected; analysis was performed for VLF, HF, and LF/HF ratio. HRV during the rest time and each 15-min interval of the recovery time were compared. An analysis of the covariance was performed to adjust for the HF band and LF/HF ratio as confounding variables of the VLF component.

HF and VLF bands significantly decreased and the LF/HF ratio significantly increased during the task compared with those during rest time. During recovery, the VLF band was significantly decreased compared with the rest time. After the task, the HF band and LF/HF ratio immediately returned to baseline and were not significantly different from the resting values. After adjusting for HF and LF/HF ratio, the VLF band had significantly decreased compared with that during rest.

The VLF band is the “slow recovery” component and the HF band and LF/HF ratio are the “quick recovery” components of HRV. This VLF characteristic may clarify the unexplained association of the VLF band in cardiovascular disease prevention.

The effects of acute psychological stress on circulating and stimulated inflammatory markers: A systematic review and meta-analysis

Inflammatory reactivity to acute laboratory stress is thought to reflect individual differences in responsivity to environmental stressors and may confer future health risk. To characterize this response, we conducted a meta-analysis of 34 studies that measured circulating inflammatory markers and 15 studies that measured stimulated production of inflammatory markers before and after exposure to laboratory challenge. Results showed significant stress-related increases in circulating interleukin (IL)-1β (d=0.66, p<0.001), IL-6 (d=0.35, p<0.001), IL-10 (d=0.69, p<0.001), and tumor necrosis factor(TNF)-α (d=0.28, p<0.001), but not IL-1ra, IL-2, interferon-γ, or C-reactive protein. There were sufficient data to assess the time course of IL-6, IL-1β, and TNF-α reactivity. IL-6 increased from baseline to measures taken 40-50, 60-75, 90, and 120min following stress, with the largest effect at 90min post-stress (d=0.70, p<0.001). IL-1β increased from baseline to 20-30, 40-50, and 60-70min following stress, with the largest effect between 40 and 50min post-stress (d=0.73, p=0.02). For TNF-α, there was a significant increase from baseline to 31-50min post stress (d=0.44, p=0.01), but not at later times. There was no difference in magnitude of IL-6 reactivity as a function of type of stress (social-evaluative versus other). For stimulated inflammatory markers, results showed stress-related increases in IL-1β when measured 20-120min post-stress (d=1.09, p<0.001), and in IL-4 and interferon-γ when measured 0-10min post stressor (d=-0.42, p<0.001 and d=0.47, p<0.001). These results extend findings from a prior meta-analysis (Steptoe et al., 2007) to show reliable increases in circulating IL-6, IL-1β, IL-10 and TNF-α and stimulated IL-1β, IL-4 and interferon-γ in response to acute stress. It is possible that these responses contribute to associations between exposure to life challenges and vulnerability to inflammatory disease.

Cytokines in Endocrine Dysfunction of Plasma Cell Disorders

Monoclonal gammopathies (MG) are classically associated with lytic bone lesions, hypercalcemia, anemia, and renal insufficiency. However, in some cases, symptoms of endocrine dysfunction are more prominent than these classical signs and misdiagnosis can thus be possible. This concerns especially the situation where the presence of M-protein is limited and the serum protein electrophoresis (sPEP) appears normal. To understand the origin of the endocrine symptoms associated with MG, we overview here the current knowledge on the complexity of interactions between cytokines and the endocrine system in MG and discuss the perspectives for both the diagnosis and treatments for this class of diseases. We also illustrate the role of major cytokines and growth factors such as IL-6, IL-1β, TNF-α, and VEGF in the endocrine system, as these tumor-relevant signaling molecules not only help the clonal expansion and invasion of the tumor cells but also influence cellular metabolism through autocrine, paracrine, and endocrine mechanisms. We further discuss the broader impact of these tumor environment-derived molecules and proinflammatory state on systemic hormone signaling. The diagnostic challenges and clinical work-up are illustrated from the point of view of an endocrinologist.

Meta-analytical assessment of the effects of protocol variations on cortisol responses to the Trier Social Stress Test

BACKGROUND

The Trier Social Stress Test (TSST) is one of the most widely used laboratory stress tests. Exposure to this psychosocial stressor has been shown to stimulate an acute cortisol stress response in the majority of healthy individuals, while deviations from the typical pattern, i.e., cortisol reactivity dysfunctions have been linked to an ever-increasing number of negative health outcomes. However, significant variability between labs exists in strength of observed cortisol responses in healthy individuals. This variability raises the question of how to distinguish across labs between cortisol stress response patterns that reflect health risk from those that are due to methodological differences. Thus, we propose a systematic review and meta-analysis that aims at quantifying the effects of methodological variation in study and TSST protocol elements on cortisol stress responses in healthy individuals.

METHODS

Literature searches were conducted using standard databases for English language with key words including Trier Social Stress Test, TSST, Cortisol, and Laboratory Stressor among others. 186 studies met our inclusion criteria of healthy human participants without systemic immunological or endocrine dysfunction and provided sufficient information to compute a total of 237 sub-sample effect sizes.

RESULTS AND DISCUSSION

With regard to study protocol variations that may risk confounding baseline cortisol values and thus influence subsequent reactivity measures, meta-analytical examination revealed that acclimation periods pre-TSST below 30 or perhaps even 15min may suffice, at least as long as no interfering activities, i.e., questionnaires, are taking place during that timeframe. Assessing the effects of TSST protocol variations on cortisol response strength, several observations are noteworthy. First, shortening speech preparation time did not change cortisol responses in any way, nor did including questionnaires during that period show an effect. As such, our findings suggest that speech preparation time is one TSST element that can be used to reduce the burden for participants as well as laboratory logistics. Secondly, having an all female panel and instructing panel members to show negative instead of neutral behavior towards the participants both were associated with considerably reduced cortisol stress response strengths. Thirdly, several variables of interest, such as content of the speech task or gender match between active panel member and participant, were problematic to evaluate due to the large number of studies not reporting those details. This calls for future studies to report more details regarding potentially relevant protocol specifications.

HPA-axis and inflammatory reactivity to acute stress is related with basal HPA-axis activity

INTRODUCTION

Inflammation is drawing attention as pathway between psychosocial stress and health, and basal HPA axis activity has been suggested to exert a consistent regulatory influence on peripheral inflammation. Here we studied the relationship between basal HPA axis activity and inflammatory and HPA axis acute stress reactivity.

METHODS

We recruited 48 healthy individuals and collected saliva for diurnal cortisol sampling at 6 points. Participants were previously exposed to the Trier Social Stress Test (TSST) on two consecutive days. Plasma interleukin-6 (IL-6) and salivary cortisol reactivity to acute stress were measured, and their relationships with basal HPA axis activity were analyzed.

RESULTS

Steeper cortisol awakening response (CAR) linear increase was related with stronger cortisol stress reactivity (γ=0.015; p=0.042) and marginally significantly with greater habituation (γ=0.01; p=0.066). Greater curvilinearity of CAR was related with stronger cortisol reactivity (γ=-0.014; p=0.021) and greater cortisol habituation (γ=-0.011; p=0.006). Steeper daily linear decline was related with significant or marginally significantly stronger cortisol and IL-6 reactivity (cortisol: γ=-0.0004; p=0.06; IL-6: γ=-0.028; p=0.031) and greater habituation (cortisol: γ=-0.002; p=0.009, IL-6: γ=-0.015; p=0.033). Greater curvilinearity of daily decline was related with stronger IL-6 reactivity (γ=0.002; p=0.024) and also greater cortisol and IL-6 habituation (cortisol: γ=0.00009; p=0.03, IL-6: γ=0.001; p=0.024).

CONCLUSIONS

Patterns of basal HPA axis activity that are related with healthier outcomes were found to be related with stronger initial cortisol and IL-6 reactivity and greater habituation. This is an important step in understanding the long-term health implications of acute stress responsiveness, and future studies should employ longitudinal designs to identify the direction of these relationships.

Stronger hypothalamus-pituitary-adrenal axis habituation predicts lesser sensitization of inflammatory response to repeated acute stress exposures in healthy young adults

Effective adjustment of the stress systems to repeated stress is regarded as an adaptive response of the organism facing environmental threats. Given the intertwined relationship between the stress systems and the inflammatory system, it could be expected that inflammatory processes should adapt to repeated stress as well. However, only little is known about adaptational processes of the different components of the immune system in response to repeated stress, and how these might be related to adaptational processes of the hypothalamus-pituitary-adrenal (HPA) axis. We here examined N=22 healthy participants (mean age 23years, 50% female) and exposed them to a standardized laboratory stressor twice, 24h apart. Plasma interleukin 6 (IL-6), salivary cortisol and psychometric parameters were assessed repeatedly up to 120min post stress. Results revealed a significant day by time interaction for cortisol (F=5.06; p=0.013) and IL-6 (F=4.42; p=0.041), indicating habituation of HPA axis and sensitization of inflammatory stress responses. Cortisol habituation and inflammatory sensitization were inversely related when controlling for sex (r=-0.44; p=0.044). Explorative analyses revealed significant associations between the IL-6 response on the second exposure with perceived stress (r=0.58; p=0.004), vital exhaustion (r=0.57; p=0.009), depression (r=0.47; p=0.026) and purpose in life (r=-0.50; p=0.04). These findings may help to increase understanding of the still only rudimentary understood interplay of adaptational processes of endocrine and immune responses to repeated stress and might indicate a link between inflammatory disinhibition and psychological indicators of well-being.

The Trier Social Stress Test: Principles and practice

Researchers interested in the neurobiology of the acute stress response in humans require a valid and reliable acute stressor that can be used under experimental conditions. The Trier Social Stress Test (TSST) provides such a testing platform. It induces stress by requiring participants to make an interview-style presentation, followed by a surprise mental arithmetic test, in front of an interview panel who do not provide feedback or encouragement. In this review, we outline the methodology of the TSST, and discuss key findings under conditions of health and stress-related disorder. The TSST has unveiled differences in males and females, as well as different age groups, in their neurobiological response to acute stress. The TSST has also deepened our understanding of how genotype may moderate the cognitive neurobiology of acute stress, and exciting new inroads have been made in understanding epigenetic contributions to the biological regulation of the acute stress response using the TSST. A number of innovative adaptations have been developed which allow for the TSST to be used in group settings, with children, in combination with brain imaging, and with virtual committees. Future applications may incorporate the emerging links between the gut microbiome and the stress response. Future research should also maximise use of behavioural data generated by the TSST. Alternative acute stress paradigms may have utility over the TSST in certain situations, such as those that require repeat testing. Nonetheless, we expect that the TSST remains the gold standard for examining the cognitive neurobiology of acute stress in humans.

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The TSST is the human experimental gold standard for evaluating the neurobiology of acute stress.

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The HPA axis response to the TSST is higher in males and lower in older adults.

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Genotype and epigenetic factors moderate the neurobiological response to the TSST.

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Multiple adaptations of the TSST are available for different testing contexts.

Cardiovascular, hemodynamic, neuroendocrine, and inflammatory markers in women with and without vasomotor symptoms

OBJECTIVE

Vasomotor symptoms (VMS) may be associated with an increased risk of cardiovascular disease. One candidate mechanism may involve alterations in physiological responses to stress. The current study therefore examined the relationship between self-reported VMS bother and cardiovascular, hemodynamic, neuroendocrine, and inflammatory responses to an acute psychosocial stress protocol.

METHODS

One hundred eighty-six women in the menopausal transition or early postmenopausal stage (age 45-60 y) provided the data for this article. Subjective hot flash and night sweat bother were assessed using the Greene Climacteric Scale. Women also underwent a stressor battery involving a speech and a mental arithmetic task while cardiovascular, hemodynamic, neuroendocrine, and inflammatory responses were assessed. Repeated measures regression analyses were used to examine the relationship between self-reported VMS and physiologic responses to the stressor.

RESULTS

In multivariate analyses adjusting for potential confounders, self-reported hot flash bother was associated with lower overall cardiac index and stroke volume index and higher overall vascular resistance index and levels of the inflammatory cytokine interleukin-6. Hot flash bother also tended to be associated with higher overall cortisol levels and higher baseline levels of plasma norepinephrine. Night sweat bother, on the other hand, was associated with higher overall cortisol levels and tended to be associated with higher interleukin-6.

CONCLUSIONS

Self-reported VMS bother is associated with an unfavorable hemodynamic and neuroendocrine profile characterized by increased hypothalamic-pituitary-adrenal axis and central sympathetic activation, inflammation, and vasoconstriction. Further research investigating this profile in relation to VMS, and the potential health implications of this association, is warranted.

Sex differences in the association between stressor-evoked interleukin-6 reactivity and C-reactive protein

Individuals differ consistently in the magnitude of their inflammatory responses to acute stressors, with females often showing larger responses than males. While the clinical significance of these individual differences remains unclear, it may be that greater inflammatory responses relate to increased systemic inflammation and thereby risk for chronic inflammatory disease. Here, we examined whether acute stressor-evoked interleukin (IL)-6 responses associate with resting levels of C-reactive protein (CRP), a marker of systemic inflammation, and whether this association differs by sex. Subjects were 57 healthy midlife adults (30-51years; 33% female; 68% white). Blood was drawn before and 30-min after two mental stress tasks: a multisource interference task and a Stroop color word task. Hierarchical regressions controlling for age, sex, race, and BMI tested whether stressor-evoked IL-6 responses were associated with resting CRP and whether this association differed by sex. Results indicated that sex and stressor-evoked IL-6 responses interacted to predict CRP (ΔR²=0.08, B=-1.33, β=-0.39, p=0.02). In males, larger stressor-evoked IL-6 responses associated with higher CRP, whereas in females, stressor-evoked IL-6 responses showed a non-significant negative association with CRP. These findings indicate that inflammatory responses to acute stressors associate with resting levels of CRP; however, this association differs by sex. Previous literature suggests that there are sex differences in stressor-evoked IL-6 responses, but this is the first study to show sex differences in the relationship between acute inflammatory responses and systemic inflammation. The contribution of these sex differences to inflammatory disease risk warrants further investigation.

Associations between cytokines, endocrine stress response, and gastrointestinal symptoms in autism spectrum disorder

Many children and adolescents with autism spectrum disorder (ASD) have significant gastrointestinal (GI) symptoms, but the etiology is currently unknown. Some individuals with ASD show altered reactivity to stress and altered immune markers relative to typically-developing individuals, particularly stress-responsive cytokines including tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6). Acute and chronic stress is associated with the onset and exacerbation of GI symptoms in those without ASD. The present study examined whether GI symptoms in ASD were associated with increases in cortisol, a stress-associated endocrine marker, and TNF-α and IL-6 in response to stress. As hypothesized, a greater amount of lower GI tract symptoms were significantly associated with post-stress cortisol concentration. The relationship between cortisol response to stress and GI functioning was greater for children who had a history of regressive autism. Exploratory analyses revealed significant correlations between cortisol response, intelligence, and inappropriate speech. In contrast, symptoms of the lower GI tract were not associated with levels of TNF-α or IL-6. Significant correlations were found, however, between TNF-α and IL-6 and irritability, socialization, and intelligence. These findings suggest that individuals with ASD and symptoms of the lower GI tract may have an increased response to stress, but this effect is not associated with concomitant changes in TNF-α and IL-6. The relationship between cortisol stress response and lower GI tract symptoms in children with regressive autism, as well as the relationships between cortisol, IL-6, and intelligence in ASD, warrant further investigation.

Post-menopausal Women Exhibit Greater Interleukin-6 Responses to Mental Stress Than Older Men

BACKGROUND

Acute stress triggers innate immune responses and elevation in circulating cytokines including interleukin-6 (IL-6). The effect of sex on IL-6 responses remains unclear due to important limitations of previous studies.

PURPOSE

The purpose of this study was to examine sex differences in IL-6 responses to mental stress in a healthy, older (post-menopausal) sample accounting for several moderating factors.

METHODS

Five hundred six participants (62.9 ± 5.60 years, 55 % male) underwent 10 min of mental stress consisting of mirror tracing and Stroop task. Blood was sampled at baseline, after stress, and 45 and 75 min post-stress, and assayed using a high sensitivity kit. IL-6 reactivity was computed as the mean difference between baseline and 45 min and between baseline and 75 min post-stress. Main effects and interactions were examined using ANCOVA models.

RESULTS

There was a main effect of time for the IL-6 response (F 3,1512 = 201.57, p = <.0001) and a sex by time interaction (F 3,1512 = 17.07, p = <.001). In multivariate adjusted analyses, IL-6 reactivity was significantly greater in females at 45 min (M = 0.37 ± 0.04 vs. 0.20 ± 0.03 pg/mL, p = .01) and at 75 min (M = 0.57 ± 0.05 vs. 0.31 ± 0.05 pg/mL, p = .004) post-stress compared to males. Results were independent of age, adiposity, socioeconomic position, depression, smoking and alcohol consumption, physical activity, statin use, testing time, task appraisals, hormone replacement, and baseline IL-6. Other significant predictors of IL-6 reactivity were lower household wealth, afternoon testing, and baseline IL-6.

CONCLUSIONS

Healthy, post-menopausal females exhibit substantially greater IL-6 responses to acute stress. Inflammatory responses if sustained over time may have clinical implications for the development and maintenance of inflammatory-related conditions prevalent in older women.

The effect of experimentally induced sedentariness on mood and psychobiological responses to mental stress

BACKGROUND

Evidence suggests a link between sedentary behaviours and depressive symptoms. Mechanisms underlying this relationship are not understood, but inflammatory processes may be involved. Autonomic and inflammatory responses to stress may be heightened in sedentary individuals contributing to risk, but no study has experimentally investigated this.

AIMS

To examine the effect of sedentary time on mood and stress responses using an experimental design.

METHOD

Forty-three individuals were assigned to a free-living sedentary condition and to a control condition (usual activity) in a cross-over, randomised fashion and were tested in a psychophysiology laboratory after spending 2 weeks in each condition. Participants completed mood questionnaires (General Health Questionnaire and Profile of Mood States) and wore a motion sensor for 4 weeks.

RESULTS

Sedentary time increased by an average of 32 min/day (P = 0.01) during the experimental condition compared with control. Being sedentary resulted in increases in negative mood independent of changes in moderate to vigorous physical activity (ΔGHQ = 6.23, ΔPOMS = 2.80). Mood disturbances were associated with greater stress-induced inflammatory interleukin-6 (IL-6) responses (β = 0.37).

CONCLUSIONS

Two weeks of exposure to greater free-living sedentary time resulted in mood disturbances independent of reduction in physical activity. Stress-induced IL-6 responses were associated with changes in mood.

Stress responses to repeated exposure to a combined physical and social evaluative laboratory stressor in young healthy males

Repeated exposure to homotypic laboratory psychosocial stressors typically instigates rapid habituation in hypothalamic-pituitary-adrenal (HPA) axis-mediated stress responses in humans. However, emerging evidence suggests the combination of physical stress and social evaluative threat may be sufficient to attenuate this response habituation. Neuroendocrine, cardiovascular and subjective stress responses following repeated exposure to a combined physical and social evaluative stress protocol were assessed to examine the habituation response dynamic in this context. The speech task of the Trier social stress test (TSST; Kirschbaum et al., 1993) and the socially evaluated cold pressor task (SECPT; Schwabe et al., 2008) were administered in a combined stressor protocol. Salivary cortisol, cardiovascular and subjective stress responses to a non-stress control and repeat stressor exposure separated by six weeks were examined in males (N=24) in a crossover manner. Stressor exposure resulted in significant elevations in all stress parameters. In contrast to the commonly reported habituation in cortisol response, a comparable post-stress response was demonstrated. Cortisol, heart rate and subjective stress responses were also characterised by a heightened response in anticipation to repeated stress exposure. Blood pressure responses were comparatively uniform across repeated exposures. Findings suggest a combined physical and social evaluative stressor is a potentially useful method for study designs that require repeated presentation of a homotypic stressor.

Depression and the Link with Cardiovascular Disease

This review provides an outline of the association between major depressive disorder (MDD) and coronary heart disease (CHD). Much is known about the two individual clinical conditions; however, it is not until recently, biological mechanisms have been uncovered that link both MDD and CHD. The activation of stress pathways have been implicated as a neurochemical mechanism that links MDD and CHD. Depression is known to be associated with poorer outcomes of CHD. Psychological factors, such as major depression and stress, are now known as risk factors for developing CHD, which is as important and is independent of classic risk factors, such as hypertension, diabetes mellitus, and cigarette smoking. Both conditions have great socioeconomic importance given that depression and CHD are likely to be two of the three leading causes of global burden of disease. Better understanding of the common causal pathways will help us delineate more appropriate treatments.