Mental stress-induced hemoconcentration: Sex differences and mechanisms

Cardiovascular reactivity to acute psychological stress is associated with generalized self-efficacy and self-efficacy outcomes during adventure challenges

Outdoor adventure challenges are commonly used to enhance self-efficacy, but the physiological mechanisms involved remain unexplored. Additionally, while studies have documented the influence of self-efficacy on stress management, general self-efficacy has yet to be fully understood in the context of cardiovascular stress reactivity (CVR). This study investigated the influence of self-efficacy beliefs on CVR during acute psychological stress tasks. Additionally, it explored whether CVR serves as a novel mechanism underlying the outcomes of outdoor adventure challenges. As part of a wider randomized controlled trial, participants (n = 55) were invited to complete a laboratory session to assess CVR to an active (paced auditory serial addition test (PASAT)) and a passive (cold pressor test (CPT)) stress task. Randomized participants (n = 33) to the experimental condition also engaged in a high ropes challenge course after the laboratory session. It was found that greater self-reported self-efficacy was associated with larger CVR during the CPT and positively associated with perceived engagement and performance during the PASAT. Secondly, participants reporting positive change in self-efficacy post-intervention were associated with greater CVR and greater CVR was associated with higher ratings of intervention engagement and perceived challenge. This study provides preliminary evidence suggesting that greater efficacy beliefs may heighten CVR to passive acute psychological stressors. Habitual stress reactivity may represent a novel mechanism involved in outdoor and adventure-based interventions. Future research should continue to explore the impact of psychological variables on stress physiology and examine CVR as a potential mechanism in adventure experiences.

Emotion regulation tendencies and cardiovascular responses to repeated acute psychological stress

Poor emotion regulation has been associated with cardiovascular disease (CVD) through maladaptive cardiovascular responses to psychological stress. However, there has been scant research examining the relationship between emotion regulation and habituation of cardiovascular responses to recurrent stress, which may be more directly applicable to the experience of stress in everyday life. The aims of the current study were to examine the associations between emotion regulation tendencies and cardiovascular stress reactivity, as well as habituation of cardiovascular reactivity across repeated stressors. A sample of 453 participants (mean (SD) age = 19.5 (1.3) years; 62 % women) completed a repeated stress paradigm, which consisted of two 10-minute baselines and two identical 4-minute stress tasks, separated by a 10-minute recovery period. Heart rate (HR) was measured continuously; systolic/diastolic blood pressures (SBP/DBP) were measured every 2 min. At the end of the visit, participants completed the Emotion Regulation Questionnaire (ERQ) and Difficulties in Emotion Regulation Scale (DERS). Results indicate that impulse control difficulties when distressed (a DERS subscale) were significantly associated with blunted SBP, DBP, and HR reactivity to both stressors, as well as impaired HR habituation across the stressors. None of the ERQ subscales (cognitive reappraisal, expressive suppression) were found to be associated with cardiovascular stress reactivity or habituation. The outcomes of this study demonstrate a potential underlying physiological pathway through which impulse control difficulties when distressed may contribute to CVD risk. This study also reveals the importance of extending traditional cardiovascular stress reactivity protocols to include multiple exposures of the same stress task.

Comparison between the Effects of Acute Physical and Psychosocial Stress on Feedback-Based Learning

Stress modulates feedback-based learning, a process that has been implicated in declining mental function in aging and mental disorders. While acute physical and psychosocial stressors have been used interchangeably in studies on feedback-based learning, the two types of stressors involve distinct physiological and psychological processes. Whether the two types of stressors differentially influence feedback processing remains unclear. The present study compared the effects of physical and psychosocial stressors on feedback-based learning. Ninety-six subjects (Mage = 19.11 years; 50 female) completed either a cold pressor task (CPT) or mental arithmetic task (MAT), as the physical or psychosocial stressor, while electrocardiography and blood pressure were measured to assess cardiovascular stress reactivity (CVR). Self-ratings on the emotional valence of the stressors were also obtained. A probabilistic learning task was given prior to and after the stressors. Accuracy in selecting positive (Go accuracy) and avoiding negative stimuli (No-go accuracy) were recorded as learning outcomes. Repeated measures ANOVA and multiple regressions were used to compare the effects of two stressors and examine the effects of CVR and valence on the learning outcomes. The results showed that although the effects of CPT and MAT on feedback processing were not different, CVR and valence influenced Go and No-go accuracy, respectively. The results suggest that stress-modulated feedback-based learning involves multiple pathways and underscore the link between CVR and reward sensitivity. The findings have clinical implications and may contribute to a better understanding of human behavioral systems.

Extraversion is associated with lower cardiovascular reactivity to acute psychological stress

BACKGROUND AND AIMS

Extraversion has been associated with positive physical health outcomes, with adaptive cardiovascular responses to stress being one potential physiological mechanism. The present study examined the influence of extraversion on both cardiovascular reactivity and cardiovascular habituation to an acute psychological stress task (Paced Auditory Serial Addition Test (PASAT)) in a sample of healthy undergraduate students.

METHODS

A sample of 467 undergraduate students completed the Big Five Inventory (BFI) to assess trait extraversion and attended a single stress testing session. The testing session included two identical stress-testing protocols, each consisting of a 10-minute baseline and 4-minute PASAT. Cardiovascular parameters including heart rate (HR), systolic/diastolic blood pressure (S/DBP) and mean arterial pressure (MAP) were recorded throughout the testing session. State measures of positive affect (PA) and negative affect (NA), as well as post task measures of self-reported stress were used to assess psychological experiences of the stress task.

RESULTS

Extraversion was significantly associated with lower self-reported stress in response to the initial stress exposure, but not the second stress exposure. Higher levels of extraversion were associated with lower SBP, DBP, MAP and HR reactivity in responses to both exposures to the stressor. However, no significant associations were observed between extraversion and cardiovascular habituation to recurring psychological stress.

CONCLUSION

Extraversion is associated with lower cardiovascular reactivity to acute psychological stress and this relationship persists upon repeated exposures to the same stressor. Cardiovascular responses to stress may indicate a potential mechanism facilitating the association between extraversion and positive physical health outcomes.

Blunted cardiovascular reactivity to psychological stress and prospective health: a systematic review

Novel research demonstrates that lower or 'blunted' cardiovascular reactions to stress are associated with a range of adverse outcomes. The aim of the current review was (1) to examine the prospective outcomes predicted by blunted cardiovascular reactivity and (2) to identify a range of blunted cardiovascular reaction levels that predict these outcomes. Electronic databases were systematically searched (Medline, PsycArticles, PsycInfo, CINAHL, PubMed, Web of Science). Studies were included if they examined the prospective influence of blunted cardiovascular reactivity to psychological stress (SBP, DBP or HR) on a negative health, behavioural or psychological outcome. A total of 23 studies were included in the review. Blunted reactivity predicted (1) adverse cardiovascular health, primarily in cardiac samples (e.g., myocardial infarction, carotid atherosclerosis) and (2) outcomes associated with motivational and behavioural dysregulation in healthy samples (e.g., obesity, smoking addiction, depression). The cardiovascular reactivity threshold levels that were predictive of adverse health outcomes ranged between -3.00-12.59 bpm (14.41% to 136.59% lower than the sample mean) and -2.4-5.00 mmhg (65.99% to 133.80% lower than sample mean), for HR and DBP respectively. We posit that blunted reactions lower than, or equal to, the ranges reported here may be utilised by clinicians and researchers to identify individuals who are at increased risk of adverse cardiovascular health outcomes, as well as outcomes associated with motivational and behavioural dysregulation.

Role for μ-opioid receptor in antidepressant effects of δ-opioid receptor agonist KNT-127

Previous pharmacological data have shown the possible existence of functional interactions between μ- (MOP), κ- (KOP), and δ-opioid receptors (DOP) in pain and mood disorders. We previously reported that MOP knockout (KO) mice exhibit a lower stress response compared with wildtype (WT) mice. Moreover, DOP agonists have been shown to exert antidepressant-like effects in numerous animal models. In the present study, the tail suspension test (TST) and forced swim test (FST) were used to examine the roles of MOP and DOP in behavioral despair. MOP-KO mice and WT mice were treated with KNT-127 (10 mg/kg), a selective DOP agonist. The results indicated a significant decrease in immobility time in the KNT-127 group compared with the saline group in all genotypes in both tests. In the saline groups, immobility time significantly decreased in MOP-KO mice compared with WT mice in both tests. In female MOP-KO mice, KNT-127 significantly decreased immobility time in the TST compared with WT mice. In male MOP-KO mice, however, no genotypic differences were found in the TST after either KNT-127 or saline treatment. Thus, at least in the FST and TST, the activation of DOP and absence of MOP had additive effects in reducing measures of behavioral despair, suggesting that effects on this behavior by DOP activation occur independently of MOP.

Sedentary behaviour, but not moderate-to-vigorous physical activity, is associated with respiratory responses to acute psychological stress

BACKGROUND

Acute psychological stress induces respiratory responses, and stress-induced respiratory changes can be used to non-invasively reflect metabolic regulation. Respiratory and cardiovascular responses to stress are both driven by sympathetic mechanisms. Higher volumes of sedentary behaviour and lower volumes of physical activity are associated with elevated sympathetic tone and larger cardiovascular responses to stress. The aim of this study was to test whether these associations translate to measures of respiratory stress reactivity.

METHODS

Daily hours of sedentary behaviour (thigh-mounted activPAL) and moderate-to-vigorous physical activity (MVPA; wrist-mounted ActiGraph) were assessed across seven days. Breath-by-breath respiratory (e.g., breathing frequency [BF], end-tidal carbon dioxide partial pressure [PetCO₂], carbon dioxide output [V̇CO₂] and respiratory exchange ratio [RER]) responses to an 8-min Paced Auditory Serial Addition Test were then measured using a Cortex MetaLyzer3B.

RESULTS

Healthy participants (N = 61, mean age ± SD = 25.7 ± 8.9 years) recorded high volumes of sedentary behaviour (9.96 ± 1.48 h/day) and MVPA (1.70 ± 0.71 h/day). In adjusted models (with the inclusion of sedentary behaviour, MVPA, and other a priori selected covariates) hours of daily sedentary behaviour were associated with baseline to stress changes in BF (Β = 0.695, 95% CI = 0.281 - 1.109, p = .014), V_T (Β = -0.042, 95% CI = -0.058 - -0.026, p = .014), PetCO₂ (Β = -0.537, 95% CI = -0.829 - -0.245, p = .014), V̇CO₂ (Β = -0.008, 95% CI = -0.014 - -0.003, p = .030), and RER (Β = -0.013, 95% CI = -0.021 - -0.005, p = .022). Daily hours of MVPA were not linked with respiratory responses to stress.

DISCUSSION

Sedentary behaviour, but not MVPA, is associated with respiratory stress reactivity. Future work should untangle the underlying mechanisms of these findings and explore the consequences for cardiometabolic disease.

Effects of anchoring sutures at diverting ileostomy after rectal cancer surgery on peritoneal adhesion at following ileostomy reversal

Purpose

During diverting ileostomy reversal for rectal cancer patients who underwent previous sphincter-saving surgery, the extent of adhesion formation around the ileostomy site affects operative and postoperative outcomes. Anchoring sutures placed at the time of the ileostomy procedure may reduce adhesions around the ileostomy. This study aimed to evaluate the effects of anchoring sutures on the degree of adhesion formation and the postoperative course at the time of ileostomy reversal.

Methods

Patients who underwent sphincter-saving surgery with diverting ileostomy for rectal cancer between January 2013 and December 2017 were enrolled. Variables including the peritoneal dhesion index (PAI) score, operation time, the length of resected small bowel, operative complications, and postoperative hospital stay were collected prospectively and compared between the anchoring group (AG) and non-anchoring group (NAG).

Results

A total of 90 patients were included in this study, with 60 and 30 patients in the AG and NAG, respectively. The AG had shorter mean operation time (46.88 ± 16.37 minutes vs. 61.53 ± 19.36 minutes, P = 0.001) and lower mean PAI score (3.02 ± 2.53 vs. 5.80 ± 2.60, P = 0.001), compared with the NAG. There was no significant difference in the incidence of postoperative complications between the AG and NAG (5.0% vs. 13.3%, respectively; P = 0.240).

Conclusion

Anchoring sutures at the formation of a diverting ileostomy could decrease the adhesion score and operation time at ileostomy reversal, thus may be effective in improving perioperative outcomes.

Adverse childhood experiences, sex, and cardiovascular habituation to repeated stress

Adverse childhood experiences (ACEs) are robustly associated with later cardiovascular disease. Alterations in cardiovascular responses to stress may be an underlying mechanism. The present study examined whether ACEs predicted habituation of cardiovascular responses across two acute laboratory stress tasks, and whether this differed between men and women. During a single laboratory visit, 453 healthy young adults completed two identical stress-inducing protocols, each involving a 10-minute baseline and 4-minute acute psychological stress task. Heart rate (HR) and systolic/diastolic blood pressure (S/DBP) were recorded throughout. Participants also completed the Adverse Childhood Experiences scale. Cardiovascular responses habituated from the first to second stress task on average across the entire sample. However, women-but not men-with higher self-reported ACEs displayed less habituation of HR and DBP, but not SBP, across the stress tasks. Results suggest that ACEs may alter the body's ability to adaptively respond to stress exposures in adulthood, specifically in women.

Effects of arousal reappraisal on the anxiety responses to stress: Breaking the cycle of negative arousal intensity and arousal interpretation

Arousal reappraisal has been shown to be an effective strategy during stress to improve anxiety. However, the exact psychological mechanism through which arousal reappraisal improves anxiety is unknown. In a large, cross-sectional study (Study 1, N = 455) participants engaged in an acute psychological stress task and rated their levels of physiological arousal, cognitive anxiety, and somatic anxiety, and whether they perceived this physiological arousal, cognitive anxiety, and somatic anxiety as helpful or hurtful (i.e., interpretation). Structural equation models supported a previously hypothesized model demonstrating that higher levels of physiological arousal were interpreted more negatively and this negative interpretation was associated with higher levels of anxiety intensity and more negative interpretations of anxiety. In an independent sample (Study 2, N = 155), participants were randomly assigned to an arousal reappraisal intervention or control condition prior to engaging in the psychological stress task. Results indicated that arousal reappraisal resulted in more positive interpretations of physiological arousal and anxiety. Results also supported a previously hypothesized model demonstrating that arousal reappraisal 'broke' the connection between physiological arousal intensity and physiological arousal interpretation. The present studies suggest that arousal reappraisal could possibly be acting through improving interpretations of physiological arousal symptoms.

Trait neuroticism does not relate to cardiovascular reactivity or habituation to repeated acute psychosocial stress

Neuroticism has been associated with adverse cardiovascular health. Adverse cardiovascular health outcomes have also been linked to cardiovascular reactivity and cardiovascular reactivity habituation to acute psychosocial stress. As such, cardiovascular stress reactivity and habituation may be a factor in the association between neuroticism and disease risk. However, studies of the relationship between neuroticism and cardiovascular reactivity have produced mixed results. Moreover, the relationships between neuroticism, cardiovascular reactivity habituation, and general affect across a repeated stress paradigm have not been examined. The present study aimed to assess the relationships between neuroticism, positive and negative affect, and cardiovascular reactivity and habituation to acute psychosocial stress in a large, demographically diverse sample. Participants (N = 426) completed two 4-min mental arithmetic stressors, each with a separate baseline, in a single laboratory session while having discrete blood pressure and heart rate measurements taken. State positive and negative affect were measured immediately following informed consent, after receiving task instructions, and after each stress task. Trait neuroticism was measured using the Big Five Inventory. Each stress task elicited significant cardiovascular changes. Trait neuroticism was not significantly associated with cardiovascular reactivity or cardiovascular reactivity habituation, within or across stress tasks (all p's > 0.12). Across the entire study protocol, neuroticism was significantly related to lower positive affect and higher negative affect (both p's < 0.001). Trait neuroticism did not relate to stress-related cardiovascular adjustments but might confer a predisposition toward high negative affect.

Mastery Imagery Ability Is Associated With Positive Anxiety and Performance During Psychological Stress

Mastery imagery (i.e., images of being in control and coping in difficult situations) is used to regulate anxiety. The ability to image this content is associated with trait confidence and anxiety, but research examining mastery imagery ability's association with confidence and anxiety in response to a stressful event is scant. The present study examined whether trait mastery imagery ability mediated the relationship between confidence and anxiety, and the subsequent associations on performance in response to an acute psychological stress. Participants (N = 130; 55% male; M_age = 19.94 years; SD = 1.07 years) completed assessments of mastery imagery ability and engaged in a standardized acute psychological stress task. Immediately prior to the task, confidence, cognitive and somatic anxiety intensity, and interpretation of anxiety symptoms regarding the task were assessed. Path analyses supported a model whereby mastery imagery ability mediated the relationship between confidence and cognitive and somatic anxiety interpretation. Greater mastery imagery ability and confidence were both directly associated with better performance on the stress task. Mastery imagery ability may help individuals experience more facilitative anxiety and perform better during stressful tasks. Improving mastery imagery ability by enhancing self-confidence may help individuals successfully cope with anxiety elicited during stressful situations.

Focusing attention on biological markers of acute stressor intensity: Empirical evidence and limitations

ARMARIO, A, J. Labad and R. Nadal. Focusing attention on biological markers of acute stressor intensity: empirical evidence and limitations. NEUROSCIENCE AND BIOBEHAVIORAL REVIEWS. The availability of biological markers that objectively quantify stress is a highly relevant issue. However, experimental evidence suggests that most physiological changes elicited by emotional stressors do not reflect their intensity and are not useful for this purpose. Thus, we review experimental evidence in animals and humans about the putative validity of neuroendocrine and sympathetic/parasympathetic variables to measure stress. Plasma levels of some hormones (e.g. ACTH, glucocorticoids, prolactin and catecholamines) have been found to reflect, at least under certain conditions, the intensity of emotional stressors in animals and probably in humans. However, the temporal resolution of hormone changes is insufficient to reflect the very dynamic psychological processes taking place while experiencing stressors. Cardiovascular parameters (e.g. heart rate and blood pressure) have much better temporal resolution but their validity as markers of stressor intensity either in animals or humans is problematic. Skin conductance and pupil dilation appear to be promising. Additional and more systematic studies are needed to demonstrate the actual validity of stress-induced physiological changes to quantify stress.

Associations between heart rate, perceived heart rate, and anxiety during acute psychological stress

Background: Acute psychological stress elicits increases in heart rate (HR) and anxiety. Theories propose associations between HR, perceived HR, and anxiety during stress. However, anxiety is often measured as a unidimensional construct which limits a comprehensive understanding of these relationships. Objectives: This research explored whether HR reactivity or perceived HR change was more closely associated with cognitive and somatic anxiety during acute psychological stress. Design: Two laboratory-based studies were conducted. Methods: In a single laboratory session, healthy male (N = 71; study 1) and female (N = 70; study 2) university students completed three laboratory psychological stress tasks (counterbalanced), each with a preceding baseline. Heart rate, perceived HR change, and cognitive and somatic anxiety intensity and interpretation of anxiety symptoms were assessed immediately following each task. Data were aggregated across tasks. Results: Actual HR change was unrelated to anxiety intensity, but was associated with more debilitative interpretations of anxiety (study 2). Perceptions of HR change were consistently associated with greater intensity of cognitive (study 1) and somatic (study 1 and 2) anxiety. Conclusions: Perceived HR rather than actual HR is more closely associated with anxiety intensity during psychological stress. The findings have implications for stress management and the clinical treatment of anxiety symptoms.

Relationship Between Haemostasis Parameters and Anxiety Under Examination Stress: A Pilot Study

This work aims to clarify how blood coagulation parameters reflect mild stress response in males and females. Healthy student volunteers of both sexes were used in this pilot study. A new global sensitive assay of haemostasis, spatial thrombodynamics, along with conventional coagulometry approach were used to evaluate of blood coagulation parameters. Psychodiagnostics scales (according to Spielberger and Taylor) are employed to evaluate anxiety as stress-induced response. We have selected exam stress, which despite being a mild stressor may nevertheless cause somatic disorders. We provide the first evidence of a statistically significant increase in initial clot growth velocity in women, but not men, in response to exam stress. The exam situation produces higher situational anxiety in female volunteers, and so they express remarkable stress-induced haemostatic responses, including plasma- and platelet-based changes. In contrast, male volunteers do not express pronounced stress-induced changes in haemostasis, and only display a decrease in plateletcrit value and an increase in prothrombin time. Mild form of stress (exam) induces changes in some blood coagulation parameters. A statistically significant remarkable increase in V_init value and some other plasma- and platelet-based parameters has been seen in female students (but not male ones) under exam stress.

Attention to Emotional Information Is Associated With Cytokine Responses to Psychological Stress

This study aimed to investigate the impact of mental stress on salivary cytokines and attention to emotional stimuli, as well as associations between stress-induced changes of immune and cognitive parameters. In a randomized order a total of 60 young adults were assigned to one of two stress conditions with varying stress intensity. High stress was induced by a socially evaluated Paced Auditory Serial Addition Test (PASAT). As a low stress task a paper-and-pencil version of PASAT was administered. Salivary cytokines were measured before, 5 min after, and 45 min after completion of the stress task, and were assayed for pro- and anti-inflammatory cytokines. Three distinct types of attention – alerting, orienting, and executive control – were measured by the modified Emotional Attention Network Test Integration (E-ANTI). IL-1β and IL-6 increased only in the high-stress group. Significant increases in IFN-α, IFN-γ, TNF-α, and IL-10 at 45 min after stress induction (all p’s < 0.05) were observed in both the high-stress and the low-stress group. Alerting attention was positively related to more pronounced increases in IFN-α and TNF-α in both groups. Further, better orienting attention after presentation of negative cues was associated with higher increases in IFN-α, TNF-α, IL-2, IL-5, and IL-10 in both groups, and higher overall levels of IFN-α, IFN-γ, and IL-12p70 in the high-stress group. There were no systematic gender differences in cytokine responses. We conclude that attention processes modulate the increases of salivary cytokines after stress exposure, and that these effects depend on stress level, particular attention network, and stimulus valence.

Acute hydrocortisone administration reduces cardiovagal baroreflex sensitivity and heart rate variability in young men

KEY POINTS

A surge in cortisol during acute physiological and pathophysiological stress may precipitate ventricular arrhythmia and myocardial infarction. Reduced cardiovagal baroreflex sensitivity and heart rate variability are observed during acute stress and are associated with an increased risk of acute cardiac events. In the present study, healthy young men received either a single iv bolus of saline (placebo) or hydrocortisone, 1 week apart, in accordance with a randomized, placebo-controlled, cross-over study design. Hydrocortisone acutely increased heart rate and blood pressure and reduced cardiovagal baroreflex sensitivity and heart rate variability in young men. These findings suggest that, by reducing cardiovagal baroreflex sensitivity and heart rate variability, acute surges in cortisol facilitate a pro-arrhythmic milieu and provide an important mechanistic link between stress and acute cardiac events ABSTRACT: Surges in cortisol concentration during acute stress may increase cardiovascular risk. To better understand the interactions between cortisol and the autonomic nervous system, we determined the acute effects of hydrocortisone administration on cardiovagal baroreflex sensitivity (BRS), heart rate variability (HRV) and cardiovascular reactivity. In a randomized, placebo-controlled, single-blinded cross-over study, 10 healthy males received either a single iv bolus of saline (placebo) or 200 mg of hydrocortisone, 1 week apart. Heart rate (HR), blood pressure (BP) and limb blood flow were monitored 3 h later, at rest and during the sequential infusion of sodium nitroprusside and phenylephrine (modified Oxford Technique), a cold pressor test and a mental arithmetic stress task. HRV was assessed using the square root of the mean of the sum of the squares of differences between successive R-R intervals (rMSSD). Hydrocortisone markedly increased serum cortisol 3 h following infusion and also compared to placebo. In addition, hydrocortisone elevated resting HR (+7 ± 4 beats min^-1 ; P < 0.001) and systolic BP (+5 ± 5 mmHg; P = 0.008); lowered cardiovagal BRS [geometric mean (95% confidence interval) 15.6 (11.1-22.1) ms/mmHg vs. 26.2 (17.4--39.5) ms/mmHg, P = 0.011] and HRV (rMSSD 59 ± 29 ms vs. 84 ± 38 ms, P = 0.004) and increased leg vasoconstrictor responses to cold pressor test (Δ leg vascular conductance -45 ± 20% vs. -23 ± 26%; P = 0.023). In young men, an acute cortisol surge is accompanied by increases in HR and BP, as well as reductions in cardiovagal BRS and HRV, potentially providing a pro-arrhythmic milieu that may precipitate ventricular arrhythmia or myocardial infarction and increase cardiovascular risk.

Increased stressor-evoked cardiovascular reactivity is associated with reduced amygdala and hippocampus volume

Exaggerated cardiovascular reactivity to acute psychological stress is associated with an increased risk of developing cardiovascular disease. The amygdala and hippocampus have been implicated in centrally mediating stressor-evoked cardiovascular reactivity. However, little is known about the associations of amygdala and hippocampus morphology with stressor-evoked cardiovascular reactivity. Forty (M_age = 19.05, SD = 0.22 years) healthy young women completed two separate testing sessions. Session 1 assessed multiple parameters of cardiovascular physiology at rest and during a validated psychological stress task (Paced Auditory Serial Addition Test), using electrocardiography, Doppler echocardiography, and blood pressure monitoring. In Session 2, 1 year later, structural MRI was conducted. Brain structural volumes were computed using automated segmentation methods. Regression analyses, following Benjamini-Hochberg correction, showed that greater heart rate and cardiac output reactivity were associated with reduced amygdala and hippocampus gray matter volume. Systolic blood pressure reactivity was associated with reduced hippocampus volume. In contrast, no associations between diastolic blood pressure, mean arterial blood pressure, stroke volume, or total peripheral resistance reactivity with amygdala or hippocampus volumes were apparent. Comparison analyses examining insula volume found no significant associations. Some indicators of greater stressor-evoked cardiovascular reactivity associate with reduced amygdala and hippocampus gray matter volume, but the mechanisms of this association warrant further study.

The Effects of Training Contingency Awareness During Attention Bias Modification on Learning and Stress Reactivity

Current attention bias modification (ABM) procedures are designed to implicitly train attention away from threatening stimuli with the hope of reducing stress reactivity and anxiety symptoms. However, the mechanisms underlying effective ABM delivery are not well understood, with awareness of the training contingency suggested as one possible factor contributing to ABM efficacy. Here, 45 high-anxious participants were trained to divert attention away from threat in two ABM sessions. They were randomly assigned to one of three training protocols: an implicit protocol, comprising two standard implicit ABM training sessions; an explicit protocol, comprising two sessions with explicit instruction as to the attention training contingency; and an implicit-explicit protocol, in which participants were not informed of the training contingency in the first ABM session and informed of it at the start of the second session. We examined learning processes and stress reactivity following a stress-induction task. Results indicate that relative to implicit instructions, explicit instructions led to stronger learning during the first training session. Following rest, the explicit and implicit groups exhibited consolidation-related improvement in performance, whereas no such improvement was noted for the implicit-explicit group. Finally, although stress reactivity was reduced after training, contingency awareness did not yield a differential effect on stress reactivity measured using both self-reports and skin conductance, within and across sessions. These results suggest that explicit ABM administration leads to greater initial learning during the training protocol while not differing from standard implicit administration in terms of off-line learning and stress reactivity.

The effects of a psychological intervention directed at optimizing immune function: study protocol for a randomized controlled trial

Background

Previous research has provided evidence for the link between psychological processes and psychophysiological health outcomes. Psychological interventions, such as face-to-face or online cognitive behavioral therapy (CBT) and serious games aimed at improving health, have shown promising results in promoting health outcomes. Few studies so far, however, have examined whether Internet-based CBT combined with serious gaming elements is effective in modulating health outcomes. Moreover, studies often did not incorporate psychophysiological or immunological challenges in order to gain insight into physiological responses to real-life challenges after psychological interventions. The overall aim of this study is to investigate the effects of a psychological intervention on self-reported and physiological health outcomes in response to immune and psychophysiological challenges.

Methods/design

In a randomized controlled trial, 60 healthy men are randomly assigned to either an experimental condition, receiving guided Internet-based (e-health) CBT combined with health-related serious gaming elements for 6 weeks, or a control condition receiving no intervention. After the psychological intervention, self-reported vitality is measured, and participants are given an immunological challenge in the form of a Mycobacterium bovis Bacillus Calmette-Guérin (BCG) vaccination. One day after the vaccination, participants are asked to perform several psychophysiological tasks in order to explore the effects of the psychological intervention on participants’ stress response following the immune challenge. To assess the delayed effects of vaccination on self-reported and physiological health outcomes, a follow-up visit is planned 4 weeks later. Total study duration is approximately 14 weeks. The primary outcome measure is self-reported vitality measured directly after the intervention. Secondary outcome measures include inflammatory and endocrine markers, as well as psychophysiological measures of heart rate and skin conductance in response to the psychophysiological tasks after the BCG vaccination.

Discussion

The innovative design features of this study – e.g., combining guided e-health CBT with health-related serious gaming elements and incorporating immunological and psychophysiological challenges – will provide valuable information on the effects of a psychological intervention on both self-reported and physiological health outcomes. This study will offer further insights into the mechanisms underlying the link between psychological factors and health outcomes and is anticipated to contribute to the optimization of health care strategies.

Trial registration

Nederlands Trial Register, NTR5610. Registered on 4 January 2016.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-1983-7) contains supplementary material, which is available to authorized users.

Anxiety symptom interpretation: A potential mechanism explaining the cardiorespiratory fitness-anxiety relationship

BACKGROUND

Higher cardiorespiratory fitness is associated with lower trait anxiety, but research has not examined whether fitness is associated with state anxiety levels and the interpretation of these symptoms. The aim of this paper was to (1) reexamine the association between cardiorespiratory fitness and general anxiety and (2) examine anxiety intensity and perceptions of these symptoms prior to an acute psychological stress task.

METHODS

Participants (N=185; 81% female; Mage=18.04, SD=0.43 years) completed a 10-minute Paced Serial Addition Test. General anxiety was assessed using the anxiety subscale of the Hospital Anxiety Depression Scale. Cognitive and somatic anxiety intensity and perceptions of symptoms was assessed immediately prior to the acute psychological stress task using the Immediate Anxiety Measures Scale. Cardiorespiratory fitness was calculated using a validated standardized formula.

RESULTS

Higher levels of cardiorespiratory fitness were associated with lower levels of general anxiety. Path analysis supported a model whereby perceptions of anxiety symptoms mediated the relationship between cardiorespiratory fitness and levels of anxiety experienced during the stress task; results remained significant after adjusting for general anxiety levels. Specifically, higher levels of cardiorespiratory fitness were positively associated with more positive perceptions of anxiety symptoms and lower levels of state anxiety.

LIMITATIONS

A standard formula rather than maximal testing was used to assess cardiorespiratory fitness, self-report questionnaires were used to assess anxiety, and the study was cross-sectional in design.

CONCLUSIONS

Results suggest a potential mechanism explaining how cardiorespiratory fitness can reduce anxiety levels.

Predisposing factors to post-operative adhesion development

BACKGROUND

Adhesion development is the most common sequelae of intra-abdominal and pelvic surgery and represents a significant, yet poorly understood, cause of morbidity among post-operative patients. It remains unclear, for example, exactly why adhesions form more frequently in certain tissues and/or patients, or at specific locations within them, as opposed to others. This review contributes to the growing knowledge pool by elucidating factors that potentially predispose to the development of adhesions. Given the strong correlation between a hypofibrinolytic state and adhesion formation, this review article will examine not only those factors that have been shown to directly predispose to adhesion development, but also those that are likely do so indirectly by means of altering the coagulation/fibrinolytic profile.

METHODS

A literature search was performed using the PubMed database for all relevant English language articles up to February 2014. All of the identified articles were reviewed with particular attention to predisposing factors to post-operative adhesion development. In addition, the reference lists of each article were reviewed to identify additional relevant articles.

RESULTS

Various factors have been shown to directly increase the risk of post-operative adhesion development; namely, certain genetic polymorphisms in the interleukin-1 receptor antagonist, increased estrogen exposure, and endometriosis. In addition, numerous factors are known to increase the risk of fibrosis, therefore likely increasing the risk of adhesion development indirectly. These factors include genetic polymorphisms in plasminogen activator inhibitor-1 and thrombin-activatable fibrinolysis inhibitor, diabetes mellitus, metabolic syndrome, hyperglycemia, obesity, depression, binge alcohol consumption, anti-Parkinsonian medications, oral hormone therapy, pregnancy, and cancer.

CONCLUSIONS

The literature reviewed in this paper will help to direct future research aimed at understanding the mechanisms that underlie the association of certain factors with adhesion development. This information will be crucial in the creation of adequate preventative and treatment strategies.

Reassessment of the cardio-respiratory stress response, using the king penguin as a model

Research in to short-term cardio-respiratory changes in animals in reaction to a psychological stressor typically describes increases in rate of oxygen consumption (V̇(O2)) and heart rate. Consequently, the broad consensus is that they represent a fundamental stressor response generalizable across adult species. However, movement levels can also change in the presence of a stressor, yet studies have not accounted for this possible confound on heart rate. Thus the direct effects of psychological stressors on the cardio-respiratory system are not resolved. We used an innovative experimental design employing accelerometers attached to king penguins (Aptenodytes patagonicus) to measure and thus account for movement levels in a sedentary yet free-to-move animal model during a repeated measures stress experiment. As with previous studies on other species, incubating king penguins (N = 6) exhibited significant increases in both V̇(O2) and heart rate when exposed to the stressor. However, movement levels, while still low, also increased in response to the stressor. Once this was accounted for by comparing periods of time during the control and stress conditions when movement levels were similar as recorded by the accelerometers, only V̇(O2) significantly increased; there was no change in heart rate. These findings offer evidence that changing movement levels have an important effect on the measured stress response and that the cardio-respiratory response per se to a psychological stressor (i.e. the response as a result of physiological changes directly attributable to the stressor) is an increase in V̇(O2) without an increase in heart rate.

Induced mild systemic inflammation is associated with impaired ability to improve cognitive task performance by practice

Elevated inflammatory levels are linked to poorer cognition, but experimental confirmation is lacking. This report examined associations between cognitive performance and inflammation induced by exercise and vaccination. Thirty-six (exercise N = 18, vaccination N = 18) healthy males completed a paced auditory serial addition test (PASAT), which is a multifaceted measure of cognitive function. The task was completed in placebo and elevated inflammation states. Improvements in PASAT performance were related to inflammation. In the exercise study, IL-6 during the first PASAT negatively correlated with PASAT improvement (p = .022). In the vaccination study, increases in C-reactive protein between PASATs correlated with reduced PASAT improvement (p < .001). Inflammation was linked to reduced improvements in cognitive performance. Further research should identify the specific cognitive functions affects and the underlying mechanisms.

Vaccine-induced inflammation attenuates the vascular responses to mental stress

Inflammation is associated with poorer vascular function, with evidence to suggest that inflammation can also impair the vascular responses to mental stress. This study examined the effects of vaccine-induced inflammation on vascular responses to mental stress in healthy participants. Eighteen male participants completed two stress sessions: an inflammation condition having received a typhoid vaccination and a control (non-inflamed) condition. Tumor necrosis factor-alpha and interleukin-6 (p's<.001) increased following vaccination, confirming modest increases in inflammation. Mental stress increased blood flow, blood pressure, heart rate, and cardiac output in both conditions (all p's<.001), but the blood flow response to stress was attenuated having received the vaccination compared to the control condition (p's<.05). These results further implicate the interaction between inflammation and the vasculature as a mechanism through which stress may trigger myocardial infarction.

The effect of acute mental stress on limb vasodilation is unrelated to total peripheral resistance

Mental stress can trigger myocardial infarction, with poor vascular responses to stress implicated as a pathway. Vascular stress reactivity can be assessed by different methods, such as total peripheral resistance (TPR) and forearm blood flow (FBF). Little is known about how these vascular assessments are linked. This was examined in two separate studies. Healthy men (Study 1: N = 29, Study 2: N = 23) completed rest and mental arithmetic (Study 1: 8 min, Study 2: 16 min). In both studies, heart rate, mean arterial pressure, and FBF increased in response to stress. In Study 1, no changes in TPR were seen, but Study 2 found stress-induced increases in TPR. FBF was not linked to TPR at any time (all ps > .05). It appears that limb vasculature and TPR responses to stress do not give the same information about impairments of the vasculature. These findings are relevant to the interpretation of prior research findings and the design of future studies on stress and vascular responses.

Eccentric-exercise induced inflammation attenuates the vascular responses to mental stress

Mental stress has been identified as a trigger of myocardial infarction (MI), with inflammation and vascular responses to mental stress independently implicated as contributing factors. This study examined whether inflammation moderates the vascular responses to mental stress. Eighteen healthy male participants completed a stress task under two counter balanced conditions. In the exercise condition, a morning bout of eccentric exercise (12×5 repetitions of unilateral eccentric knee extension at 120% intensity of concentric one repetition maximum) was used to increase levels of inflammatory-responsive cytokines during an afternoon stress session scheduled 6h later. In the control condition, participants sat and relaxed for 45min, 6h prior to the afternoon stress session. Forearm blood flow, calf blood flow (measured in the leg which completed the exercise task), blood pressure, heart rate and cardiac output were assessed at rest and in response to mental stress. As expected, interleukin-6 was higher (p=.02) 6h post exercise, i.e., at the start of the stress session, as compared to the no-exercise control condition. Mental stress increased forearm blood flow, calf blood flow, blood pressure, heart rate, and cardiac output in both conditions (p's<.001). Stress-induced calf blood flow was attenuated in the exercise condition compared to the control condition (p<.05) which was not the case for forearm blood flow. This study found that the inflammatory response to eccentric exercise attenuated the vascular responses to mental stress locally at the site of eccentric exercise-induced inflammation. The observed impairment in vascular responses to stress associated with increased levels of inflammation suggests a mechanism through which inflammation might increase the risk for MI.

Hemoconcentration and hemostasis during acute stress: interacting and independent effects

BACKGROUND

Acute psychological stress can produce significant hemoconcentration as well as prothrombotic changes in blood, both of which may have potentially harmful effects on the cardiovascular system. It is unclear whether these effects are independent or have influence on each other.

PURPOSE

This review discusses research investigating the effects of acute psychological stress on hemoconcentration and hemostasis and explores future directions for psychohematology research. Physiology, associations with cardiovascular disease, and relationships between acute psychological stress are discussed independently for hemoconcentration and hemostasis, followed by an examination of the effects of stress-hemoconcentration on hemostasis.

CONCLUSIONS

Traditional methods of adjusting for stress-hemoconcentration effects (e.g., calculated plasma volume or hematocrit level corrections) may not be appropriate when examining stress-induced changes in hemostasis. The effects of acute stress on hemostasis should be examined in conjunction with hemoconcentration.

Pentagastrin-induced hemoconcentration in healthy volunteers and patients with panic disorder: effect of pretreatment with ethinyl estradiol

Panic disorder has been associated with both an increased risk of coronary events as well as an increased risk of stroke. Hemoconcentration, with both a decrease in plasma volume and an increase in plasma viscosity, is a possible contributor to the risk of acute ischemic events. Our objectives were to demonstrate the process of hemoconcentration in response to induced panic symptoms and to assess the effect of pretreatment with ethinyl estradiol on panic-induced hemoconcentration. Fifteen male patients with panic disorder and 10 male healthy volunteers were included in a double-blind cross-over placebo-controlled design consisting of two injections of pentagastrin following randomized pretreatment with placebo and ethinyl estradiol. Plasma levels of hematocrit and hemoglobin were assessed at baseline and post-injections, and used to calculate an indirect estimation of the change in plasma volume. Pentagastrin-induced panic symptoms were associated with a mean decrease in plasma volume of 4.8% in the placebo pretreatment condition. Pretreatment with ethinyl estradiol attenuated this effect. The acute hemoconcentration observed in relation to pentagastrin-induced panic symptoms may be relevant to the increased risk of stroke and acute coronary events found in patients with panic disorder.

A general enhancement of autonomic and cortisol responses during social evaluative threat

OBJECTIVE

To examine the Social Self Preservation Theory, which predicts that stressors involving social evaluative threat (SET) characteristically activate the hypothalamic-pituitary-adrenal (HPA) axis. The idea that distinct psychosocial factors may underlie specific patterns of neuroendocrine stress responses has been a topic of recurrent debate.

METHODS

Sixty-one healthy university students (n = 31 females) performed a challenging speech task in one of three conditions that aimed to impose increasing levels of SET: performing the task alone (no social evaluation), with one evaluating observer, or with four evaluating observers. Indices of sympathetic (preejection period) and parasympathetic (heart rate variability) cardiac drive were obtained by impedance- and electrocardiography. Salivary cortisol was used to index HPA activity. Questionnaires assessed affective responses.

RESULTS

Affective responses (shame/embarrassment, anxiety, negative affect, and self-esteem), cortisol, heart rate, sympathetic and parasympathetic activation all differentiated evaluative from nonevaluative task conditions (p < .001). The largest effect sizes were observed for cardiac autonomic responses. Physiological reactivity increased in parallel with increasing audience size (p < .001). An increase in cortisol was predicted by sympathetic activation during the task (p < .001), but not by affective responses.

CONCLUSION

It would seem that SET determines the magnitude, rather than the pattern, of physiological activation. This potential to perturb broadly multiple physiological systems may help explain why social stress has been associated with a range of health outcomes. We propose a threshold-activation model as a physiological explanation for why engaging stressors, such as those involving social evaluation or uncontrollability, may seem to induce selectively cortisol release.

Hemoconcentration during a prolonged stress task: associations with hemodynamic reactivity and microvascular permeability

This study explored the association between stress-induced hemoconcentration and plasma colloid osmotic pressure, hemodynamic reactivity, and microvascular permeability during a protracted stress task in 26 healthy, young participants. Microvascular permeability was measured during rest using venous congestion plethysmography in a subsample of 13 participants. The task increased hematocrit, colloid osmotic pressure, blood pressure, and heart rate and decreased R-wave to pulse interval. Resting microvascular permeability was not correlated with hemoconcentration. Colloid osmotic pressure and diastolic blood pressure were associated with stress-induced hemoconcentration throughout the task. The association with systolic blood pressure as well as heart rate, however, was more evident during the initial 8min of the task than throughout the total task duration. These findings suggest that factors associated with hemoconcentration vary with task duration.

Blood viscosity: Effects of mental stress and relations to autonomic nervous system function and insulin sensitivity

We studied effects of mental stress on whole-blood viscosity (WBV) and blood pressure (BP), and relations between WBV and autonomic nervous system activity and insulin sensitivity. We measured WBV (rotational rheometer), plasma noradrenaline (NA), finger BP, heart rate variability (HRV) and baroreflex sensitivity (BRS; transfer technique) during hyperinsulinaemic glucose clamp and mental arithmetic stress test (MST) in 20 men with high ( > or =140/90 mmHg) and 21 men with normal (< or =115/75 mmHg) screening BP, and 10 women regardless of screening BP (all normotensive). WBV and NA increased during the MST, while HRV and BRS decreased. During the MST, WBV (all shear rates) and the response ((delta)WBV) (low shear) were higher in men with high compared to normal screening BP (p<0.05). In men, WBV correlated positively with NA and negatively with HRV, BRS and insulin sensitivity. The diastolic BP response ((delta)DBP) was independently explained by high-shear (delta)WBV (p<0.05) and (delta)NA (p<0.0001), and (delta)WBV independently by (delta)DBP (p<0.05). WBV is related to increased sympathetic activity, impaired vagal cardiac control and low insulin sensitivity in young adults. The haemorheological effect of mental stress is increased in young men with high screening BP and may be mediated by the acute increase in BP.

Complement cascade activation after an acute psychological stress task

OBJECTIVE

To examine complement cascade activation after an acute psychological stress task. Psychological stress has been implicated in the exacerbation of inflammatory disorders. Although the complement cascade is a key component of these inflammatory processes, there has been little research regarding its susceptibility to stress.

METHODS

In experiment 1, 38 healthy participants completed an 8-minute psychological stress task. Complement components were assessed from blood samples taken by venipuncture, at rest and immediately post task. In experiment 2, 40 participants undertook a similar task; blood samples were collected from a cannula at rest, immediately post task, and after 30 and 60 minutes of recovery. In experiment 3, 40 participants were exposed to both a stress and a control session. Session order was counterbalanced and, on both occasions, we received blood samples from half the participants via a cannula and the other half by repeated venipuncture.

RESULTS

In experiment 1, C3a levels increased significantly from rest to task, indicating complement cascade activation. In experiment 2, we found that both C3a and Factor Bb increased significantly from rest to task and recovered by 30 and 60 minutes. C5a rose significantly 30 minutes after completion of the stress task. In experiment 3, C3a increased in response to the mental stress task, whereas it decreased slightly during the control session. There was no significant effect of blood taking method.

CONCLUSIONS

These experiments demonstrate that the complement cascade is susceptible to acute psychological stress and suggest a potential mechanism for stress-induced inflammatory activation in individuals with inflammatory disorders.

Meningococcal A vaccination response is enhanced by acute stress in men

OBJECTIVE

To determine if acute stress experienced at the time of antigenic challenge augments the subsequent immune response.

METHODS

Sixty healthy young adults were randomized to exercise (n = 20), mental stress (n = 20) or control (n = 20) before meningococcal A+C vaccination. Antibody concentration was measured by microsphere-based antibody quantification assay at prevaccination, 4 and 20 weeks post vaccination.

RESULTS

Meningococcal serogroup A antibody responses were enhanced by exercise and mental stress in men but not women (F(2,51) = 4.00, p = .02, eta(2) = 0.135).

CONCLUSIONS

Stress-induced immune enhancement has now been demonstrated in the antibody response to thymus-independent as well as thymus-dependent vaccines. These findings indicate that this effect is not specific to T-cell involvement.

Time course and mechanisms of mental stress-induced changes and their recovery: hematocrit, colloid osmotic pressure, whole blood viscosity, coagulation times, and hemodynamic activity

The mechanisms for stress-induced changes in hematocrit and blood viscosity are unclear. Twenty-two males completed experimental (30 min baseline, 10 min mental stress, 30 min recovery) and no-stress control conditions (70 min). Hemostatic and hemodynamic activity were measured throughout. Hematocrit, colloid osmotic pressure, and blood viscosity displayed parallel patterns: a progressive increase with stress, followed by a gradual recovery. Correlational and covariance analyses indicated that the increase in hematocrit may be mediated by arterial pressure whereas recovery may be mediated by colloid osmotic pressure. Analyses also indicated that acute changes in blood viscosity may depend on hematocrit. These data suggest that stress disturbs hematocrit, colloid osmotic pressure, and blood viscosity through arterial pressure. Poststress, elevated colloid osmotic pressure may drive its own recovery and that of hematocrit and blood viscosity.

A systematic review of the effects of acute psychological stress and physical activity on haemorheology, coagulation, fibrinolysis and platelet reactivity: Implications for the pathogenesis of acute coronary syndromes

Physical activity and psychological stress are two potential triggers for the onset of acute coronary syndromes (ACS). To examine the mechanisms underlying this association, we systematically reviewed the literature to determine the effects of acute psychological stress and physical activity on haemorheology and haemostasis. Studies examining the haemorheological and haemostatic response to an acute bout of physical activity (i.e. <60 min) or laboratory psychological stress task were eligible for inclusion. The experimental evidence, although compromised by various methodological weaknesses, suggests that low and moderate intensity physical activity may be cardio-protective through beneficial effects on fibrinolytic system. High levels of physical activity, and psychological to a lesser extent, have been consistently associated with robust changes in haemorheology and haemostasis. Such findings imply that such activities may have the potential to trigger the onset of ACS, although in reality this may be limited sedentary individual and/or those with pre-existing vascular disease. In addition, the data also suggest that individuals may be at a greatest risk of stress-induced thrombogenesis in the period immediately following physical activity or psychological stress, rather than during the activity per se. In conclusion, psychological stress and physical activity may act as potential triggers for the onset of ACS via effects on haemostasis and haemorheology.

Mental stress-induced hemoconcentration and its recovery: A controlled study of time course and mechanisms

Hemoconcentration to mental stress has been implicated in acute cardiovascular events. Participants were exposed to a 30-min baseline, a 4-min stress task, and a 40-min recovery; they also undertook a 74-min no-stress control session. Hemodynamic activity was recorded and blood sampled regularly and analyzed for hematocrit, colloid osmotic pressure, and coagulation time. Hematocrit increased with stress and fully recovered after 20 min. Colloid osmotic pressure showed a similar time course. No such changes occurred in the control session. Coagulation time was not perturbed by stress. The pattern of increase in hematocrit correlated with contemporary colloid osmotic pressure and blood pressure. In recovery, only colloid osmotic pressure was strongly associated with hematocrit. The mechanisms of stress-induced hemoconcentration may differ from those responsible for recovery, which may depend primarily on colloid osmotic pressure.

The effects of the spontaneous presence of a spouse/partner and others on cardiovascular reactions to an acute psychological challenge

The presence of supportive others has been associated with attenuated cardiovascular reactivity in the laboratory. The effects of the presence of a spouse and others in a more naturalistic setting have received little attention. Blood pressure and heart rate reactions to mental stress were recorded at home in 1028 married/partnered individuals. For 112 participants, their spouse/partner was present; for 78, at least one other person was present. Women tested with a spouse/partner present showed lower magnitude systolic blood pressure and heart rate reactivity than those tested without. Individuals tested with at least one nonspousal other present also displayed attenuated reactivity. This extends the results of laboratory studies and indicates that the spontaneous presence of others is associated with a reduction in cardiovascular reactivity in an everyday environment; spouse/partner presence would appear to be especially effective for women.

Changes in plasma volume associated with mental stress ischemia in patients with coronary artery disease

Psychological stress has been shown to trigger angina and myocardial ischemia in patients with coronary artery disease. However, the mechanisms by which stress may trigger cardiac events has yet to be fully elucidated. Twenty five patients underwent radionuclide ventriculography during a multiple stress challenge. Plasma volume was assessed during rest and at the end of the stress task. Flow-mediated dilatation was also measured. Controlling for endothelial function and medications, patients with ischemia had greater reductions in plasma volume than non-ischemic patients. Reduced plasma volume may be one mechanism by which mental stress may increase the risk for acute coronary events.

Time course and mechanisms of hemoconcentration in response to mental stress

Hemoconcentration with mental stress exposure may be involved in the triggering of acute cardiovascular events. In the present study, hematocrit was measured repeatedly at baseline, during a 4 min mental stress task and during 20 min of recovery. Blood was sampled every 1-2 min throughout. Blood pressure, heart rate and R-wave to pulse interval, a measure of cardiac contractility, were measured with the same periodicity. The stress task elicited a 1.3% increase in hematocrit, which was sustained with full return to baseline level occurring only after 16 min of recovery. Between-subject correlations between hematocrit and hemodynamic activity were low. Aggregate within-subject coefficients were more impressive; the temporal profile of hematocrit correlated significantly with all hemodynamic variables. Similar within-subject analyses indicated that whereas cardiac contractility was correlated with hematocrit both during stress-related increase and subsequent recovery, blood pressure was related to hematocrit only during the increase. This suggests that stress-induced hemoconcentration may driven by different mechanisms than those which underlie its recovery.