Vaccine-induced inflammation attenuates the vascular responses to mental stress

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.

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.

Induced Inflammatory and Oxidative Markers in Cerebral Microvasculature by Mentally Depressive Stress

Background

Cerebrovascular disease (CVD) is recognized as the leading cause of permanent disability worldwide. Depressive disorders are associated with increased incidence of CVD. The goal of this study was to establish a chronic restraint stress (CRS) model for mice and examine the effect of stress on cerebrovascular inflammation and oxidative stress responses.

Methods

A total of forty 6-week-old male C57BL/6J mice were randomly divided into the CRS and control groups. In the CRS group (n = 20), mice were placed in a well-ventilated Plexiglas tube for 6 hours per day for 28 consecutive days. On day 29, open field tests (OFT) and sucrose preference tests (SPT) were performed to assess depressive-like behaviors for the two groups (n = 10/group). Macrophage infiltration into the brain tissue upon stress was analyzed by measuring expression of macrophage marker (CD68) with immunofluorescence in both the CRS and control groups (n = 10/group). Cerebral microvasculature was isolated from the CRS and controls (n = 10/group). mRNA and protein expressions of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), vascular cell adhesion molecule-1 (VCAM-1), and macrophage chemoattractant protein-1 (MCP-1) in the brain vessels were measured by real-time PCR and Western blot (n = 10/group). Reactive oxygen species (ROS), hydrogen peroxide (H₂O₂), and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) activities were quantified by ELISA to study the oxidative profile of the brain vessels (n = 10/group). Additionally, mRNA and protein expressions of NOX subunits (gp91^phox, p47^phox, p67^phox, and p22^phox) in the cerebrovascular endothelium were analyzed by real-time PCR and Western blot (n = 10/group).

Results

CRS decreased the total distances (p < 0.05) and the time spent in the center zone in OFT (p < 0.001) and sucrose preference test ratio in SPT (p < 0.01). Positive ratio of CD68⁺ was increased with CRS in the entire region of the brain (p < 0.001), reflecting increased macrophage infiltration. CRS increased the expression of inflammatory factors and oxidative stress in the cerebral microvasculature, including TNF-α (p < 0.001), IL-1β (p < 0.05), IL-6 (p < 0.05), VCAM-1 (p < 0.01), MCP-1 (p < 0.01), ROS (p < 0.001), and H₂O₂ (p < 0.001). NADPH oxidase (NOX) was activated by CRS (p < 0.01), and mRNA and protein expressions of NOX subunits (gp91^phox, p47^phox, p67^phox, and p22^phox) in brain microvasculature were found to be increased.

Conclusions

To our knowledge, this is the first study to demonstrate that CRS induces depressive stress and causes inflammatory and oxidative stress responses in the brain microvasculature.

Frequently Interrupting Prolonged Sitting With Light Body-Weighted Resistance Activity Alters Psychobiological Responses to Acute Psychological Stress: A Randomized Crossover Trial

BACKGROUND

Uninterrupted prolonged sitting and exaggerated psychobiological reactivity to acute psychological stress are associated with increased risk of cardiovascular disease (CVD). Breaking up prolonged sitting with frequent, short bouts of light-intensity physical activity acutely lowers CVD risk markers under resting conditions.

PURPOSE

To examine whether frequent interruptions to prolonged sitting with body-weighted resistance activity can acutely lower systolic blood pressure (SBP; primary outcome) and other cardiovascular (CV), inflammatory, and cortisol (secondary outcomes) responses to acute psychological stress.

METHODS

This randomized crossover trial included 17 sedentary participants (9 men; mean ± SD age; 24.0 ± 0.5 years) who completed two conditions: (i) interrupting 4 hr of sitting with 4 min of light body-weighted resistance activity every 30-min (BREAK), and (ii) 4 hr of uninterrupted sitting (SIT). Following the BREAK and SIT intervention windows, CV, inflammatory, and cortisol markers were measured at rest, during stress tasks (8-min Paced Auditory Serial Addition Test [PASAT] and 3-min cold pressor [CP]), and 45-min recovery periods.

RESULTS

There were main effects of time for CV parameters (SBP, diastolic blood pressure, heart rate, cardiac output, and total peripheral resistance [all p < .001]), inflammatory markers (interleukin-6 [IL-6]), and cortisol (p < .05) in response to stress. Time-by-condition interaction effects revealed that in the BREAK-condition there was lower SBP during immediate recovery from the CP (mean {95% confidence interval [CI]}: 127.2 [121.3, 133.4] vs 133.4 [125.5, 141.7] mmHg; p = .020), higher concentrations of plasma IL-6 45-min post-PASAT (2.70 [1.97, 3.70] vs 1.71 [1.32, 2.22] pg/mL; p = .010), and larger (nonsignificant) salivary cortisol concentrations 8-min post-CP (6.29 [4.60, 8.58] vs 3.97 [3.16, 4.99] nmol/L; p = .079).

CONCLUSIONS

Interrupting prolonged sitting with frequent bouts of light intensity body-weighted resistance activity alters psychobiological responses to acute psychological stress. Further research should explore the longer-term implications for CVD risk.

Sedentary behaviour is associated with heightened cardiovascular, inflammatory and cortisol reactivity to acute psychological stress

BACKGROUND

Sedentary behaviour is a risk factor for cardiovascular disease (CVD), but the underlying mechanisms remain unclear. Exaggerated psychobiological responses to acute psychological stress increase CVD risk. Sedentary behaviour is associated with characteristics that can predict large psychobiological stress response patterns (e.g., elevated resting blood pressure and systemic inflammation), but it is currently unknown whether sedentary behaviour and stress reactivity are directly linked. The aim of this study was to examine associations between device-assessed sedentary behaviour and measures of stress reactivity.

METHODS

Sixty-one healthy adults wore an activPAL (thigh) and ActiGraph (wrist) for seven days to measure habitual levels of sedentary behaviour (mean ± SD = 9.96 ± 1.48 h/day) and moderate-to-vigorous physical activity (mean ± SD = 101.82 ± 42.92 min/day). Participants then underwent stress reactivity testing, where beat-to-beat cardiovascular (e.g., blood pressure, total peripheral resistance), inflammatory (plasma interleukin-6, leukocytes) and salivary cortisol measurements were taken in response to an 8-minute socially evaluative Paced Auditory Serial Addition Test.

RESULTS

Higher volumes of daily sedentary behaviour were associated with larger stress responses for diastolic blood pressure (Β=1.264, 95%CI=0.537-1.990, p = .005), total peripheral resistance (Β=40.563, 95%CI=19.310-61.812, p < .001), interleukin-6 (Β=0.219, 95%CI=0.109-0.329, p < .001) and cortisol (Β=1.844, 95%CI=1.139-2.549, p < .001). These findings emerged independent of a priori determined covariates, including daily levels of moderate-to-vigorous physical activity and adiposity.

DISCUSSION

Exaggerated stress reactivity is characteristic of high sedentary behaviour and could be a novel mechanism linking sedentary behaviour with CVD. Future work should examine the impact of reducing sedentary behaviour on measures of stress reactivity, as this may have clinical relevance for preventing CVD.

An Internet-Based Psychological Intervention With a Serious Game to Improve Vitality, Psychological and Physical Condition, and Immune Function in Healthy Male Adults: Randomized Controlled Trial

Background

Recently, internet-based cognitive behavioral therapy (ICBT) and serious gaming interventions have been suggested to enhance accessibility to interventions and engagement in psychological interventions that aim to promote health outcomes. Few studies, however, have investigated their effectiveness in the context of simulated real-life challenges.

Objective

We aimed to examine the effectivity of a guided ICBT combined with a serious gaming intervention in improving self-reported psychophysiological and immunological health endpoints in response to psychophysiological and immune-related challenges.

Methods

Sixty-nine healthy men were randomly assigned to the intervention condition, receiving ICBT combined with serious gaming for 6 weeks, or the control condition, receiving no intervention. Self-reported vitality was the primary endpoint. Other self-reported psychophysiological and immunological endpoints were assessed following various challenges, including a bacillus Calmette-Guérin vaccination evoking pro-inflammatory responses, 1 and 4 weeks after the intervention period.

Results

Although the intervention did not affect vitality-associated parameters, self-reported sleep problems (P=.027) and bodily sensations (P=.042) were lower directly after the intervention compared with controls. Furthermore, wellbeing (P=.024) was higher in the intervention group after the psychophysiological challenges. Although no significant group differences were found for the psychophysiological and immunological endpoints, the data provided preliminary support for increased immunoglobulin antibody responses at the follow-up time points (P<.05). Differential chemokine endpoints between conditions were observed at the end of the test day.

Conclusions

The present study provides some support for improving health endpoints with an innovative ICBT intervention. Future research should replicate and further extend the present findings by consistently including challenges and a wide range of immune parameters into the study design.

Trial Registration

Nederlands Trial Register NTR5610; https://www.trialregister.nl/trial/5466

Influence of Acute Multispecies and Multistrain Probiotic Supplementation on Cardiovascular Function and Reactivity to Psychological Stress in Young Adults: A Double-Blind, Randomized, Placebo-Controlled Trial

OBJECTIVE

The potential influence of probiotic supplementation on cardiovascular health and stress responsivity remains largely unexplored. Some evidence suggests the possibility that probiotics may influence blood pressure. A separate body of research suggests that exaggerated cardiovascular reactions to acute psychological stress in the laboratory predict cardiovascular morbidity and mortality. The current investigation explored the effect of acute probiotic use on (1) resting cardiovascular measures in healthy young adults and (2) cardiovascular and psychological reactions to an acute psychological stressor in the laboratory.

METHOD

Participants (N = 105, M [SD] age = 20.17 [1.26], 84.8% white) completed a 2-week, double-blind, and placebo-controlled trial of a multispecies and multistrain probiotic. Exclusion criteria included previous probiotic use, diagnosed gastrointestinal disorder, and/or current antibiotic use. At visits 1 and 2, participants completed the Paced Auditory Serial Addition Test, a widely used psychological stress task. Participants were randomly assigned to a probiotic blend or matched placebo.

RESULTS

Compared with placebo, 2-week probiotic supplementation did not affect resting measures of cardiovascular function, cardiovascular responses during or recovery from stress, or psychological reactions to acute psychological stress.

CONCLUSIONS

Contrary to expectations, short-term use of a probiotic supplement in healthy participants did not influence measures of cardiovascular function or responsivity to psychological stress. Future research is needed to determine species- and strain-specific effects of probiotics in healthy participants with various degrees of stress responsiveness, as well as in diseased populations.

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.

Mathematical detection of aortic valve opening (B point) in impedance cardiography: A comparison of three popular algorithms

The preejection period (PEP) is an index of left ventricle contractility widely used in psychophysiological research. Its computation requires detecting the moment when the aortic valve opens, which coincides with the B point in the first derivative of impedance cardiogram (ICG). Although this operation has been traditionally made via visual inspection, several algorithms based on derivative calculations have been developed to enable an automatic performance of the task. However, despite their popularity, data about their empirical validation are not always available. The present study analyzes the performance in the estimation of the aortic valve opening of three popular algorithms, by comparing their performance with the visual detection of the B point made by two independent scorers. Algorithm 1 is based on the first derivative of the ICG, Algorithm 2 on the second derivative, and Algorithm 3 on the third derivative. Algorithm 3 showed the highest accuracy rate (78.77%), followed by Algorithm 1 (24.57%) and Algorithm 2 (13.82%). In the automatic computation of PEP, Algorithm 2 resulted in significantly more missed cycles (48.57%) than Algorithm 1 (6.3%) and Algorithm 3 (3.5%). Algorithm 2 also estimated a significantly lower average PEP (70 ms), compared with the values obtained by Algorithm 1 (119 ms) and Algorithm 3 (113 ms). Our findings indicate that the algorithm based on the third derivative of the ICG performs significantly better. Nevertheless, a visual inspection of the signal proves indispensable, and this article provides a novel visual guide to facilitate the manual detection of the B point.