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

Virtual stressors with real impact: what virtual reality-based biobehavioral research can teach us about typical and atypical stress responsivity

Stress contributes to transdiagnostic morbidity and mortality across a wide range of physical and mental health problems. VR tasks have been validated as stressors with robust effect sizes for VR-based stressors to evoke stress across the most common autonomic and adrenocortical stress biomarkers. However, meta-analytic validation of VR stressors have resulted in inconsistent logic: why should something that isn't real evoke a very real suite of stress responses? This review posits that conceptually addressing this question requires differentiating a cause, "stressor", from effects, "stress". Stress comprises a series of well-delineated perturbations in biological systems, such as autonomic and adrenocortical biomarkers in response to stressors. Despite their ubiquity, decades of literature have back-calculated stressor intensity based on the magnitude of a stress response. This causal directionality is not logical, yet remains pervasive because seemingly objective stress indices have generated a wealth of findings showing how stress gets under the skin and skull. This has created challenges for providing clear guidance and strategies to measure acute stressor intensity. Binary thinking about whether something is (not) real has stifled advances in understanding how to measure the dosage of a stressful environment. As a function of being programmed, individualizable, and titrated, virtual reality (VR) based stressors offer the field a platform for quantifying the dose of a stressor and generating reliable dose-response curves. This also raises the possibility to safely and ethically integrate psychosocial stressor administration into clinical and therapeutic settings. For example, Social Evaluative Threat experiments effectively trigger a stress response both in a laboratory setting and in built environments, while also upholding hard-fought trust and rapport with care providers. By focusing attention on the measurement of the stressor, VR paradigms can advance tangible understanding of stressors themselves and the pathways to the stress response.

EEG Evidence of Acute Stress Enhancing Inhibition Control by Increasing Attention

OBJECTIVE

Research about the impact of acute stress on inhibitory control remains a contentious topic, with no consensus reached thus far. This study aims to investigate the effects of acute stress on an individual's inhibitory control abilities and to elucidate the underlying neural mechanisms by analyzing resting state electroencephalogram (EEG) data.

METHODS

We recruited 32 male college students through participant recruitment information to undergo within-subject experiments under stress and non-stress conditions. Physiological indicators (cortisol and heart rate), self-report questionnaires, and behavioral data from the Stroop task were collected before, during, and after the experiment. Additionally, a five-minute eyes closed resting state EEG data collection was conducted during the Stroop task before.

RESULTS

(1) Acute stress led to a reduction in the conflict effect during the participants' Stroop task in individuals. (2) Stress resulted in an increase in the power of the beta in the resting state EEG. (3) Acute stress caused an increase in the duration of class D and an increase in the transition probabilities from classes C and B to class D in the microstates of the resting state EEG. (4) Acute stress leads to an increase in beta power values in individuals' resting state EEGs, which is significantly negatively correlated with the reduction of the conflict effect in the Stroop task under stress.

CONCLUSIONS

Acute stress can enhance individuals' attentional level, thereby promoting inhibitory control performance.

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 effects of acute versus repeated cannabidiol administration on trauma-relevant emotional reactivity: A double-blind, randomized, placebo-controlled trial

Despite the widespread use and perceived efficacy of cannabidiol (CBD) as an anxiolytic, few controlled studies have evaluated the effects of CBD on anxiety-relevant indications, and only one has done so in the context of trauma-related symptoms. The current study was designed to address this gap in the literature. Participants were 42 trauma-exposed individuals (Mage = 23.12 years, SDage = 6.61) who endorsed elevated stress. They were randomly assigned to take 300 mg of oral CBD or placebo daily for 1 week. Acute (i.e., following an initial 300 mg dose) and repeated (i.e., following 1 week of daily 300 mg dosing) effects of CBD were evaluated in relation to indicators of anxious arousal (i.e., anxiety, distress, heart rate) in response to idiographic trauma script presentation. The results of the current study suggest that relative to placebo, 300 mg CBD did not significantly reduce anxiety, B = 13.37, t(37) = 1.71, p = .096, d = 0.09, Bayes factor (BF10) = 0.54; distress, B = 15.20, t(37) = 1.31, p = .197, d = 0.07, BF10 = 0.51; or heart rate, B = -1.09, t(36) = -0.32, p = .755, d = 0.02, BF10 = 0.29, evoked by idiographic trauma script presentation in the context of acute or repeated administration. These data suggest that CBD may not effectively reduce trauma-relevant emotional arousal; however, more work is needed to confidently assert such claims due to the small sample size. The current study extends the groundwork for additional studies in this important area.

The benefit of retrieval practice on cued recall under stress depends on item difficulty

Retrieval practice, the act of recalling previously studied information, yields greater memory retention than repeated studying (retrieval practice effect). Retrieval practice can also protect memories against the negative effects of stress at retrieval in free recall tests. In cued-recall tests, however, retrieval practice may not provide complete protection against stress-related memory impairments. Here we ask whether these conflicting results may be explained by the relative difficulty of the study materials. Participants (59 men) first studied 40 Swahili-Portuguese word pairs. Half of the pairs were then repeatedly studied while the other half were repeatedly recalled. In each condition, half of the pairs were easy to remember (high in memorability) while the other half were more difficult to remember (low in memorability). Participants returned 1 week later for a final cued-recall test. Half of the participants underwent a stress-induction protocol (modified Socially Evaluated Cold Pressor Test) 25 min before the final test for all 40-word pairs; the other half underwent a control condition. Salivary cortisol and questionnaire responses were used to assess the efficacy of stress induction. Participants recalled more word pairs learned via retrieval practice than via repeated study, replicating previous research. More importantly, the results revealed an interaction such that stress decreased recall for easy items, but increased recall for difficult items that had been successfully retrieved during encoding (conditional analysis). The results suggest that the impact of stress on cued recall depends both on the learning strategy and on the intrinsic difficulty of the to-be-learned materials.

Effects of neuromodulation on cognitive and emotional responses to psychosocial stressors in healthy humans

Physiological and psychological stressors can exert wide-ranging effects on the human brain and behavior. Research has improved understanding of how the sympatho-adreno-medullary (SAM) and hypothalamic-pituitary-adrenocortical (HPA) axes respond to stressors and the differential responses that occur depending on stressor type. Although the physiological function of SAM and HPA responses is to promote survival and safety, exaggerated psychobiological reactivity can occur in psychiatric disorders. Exaggerated reactivity may occur more for certain types of stressors, specifically, psychosocial stressors. Understanding stressor effects and how the body regulates these responses can provide insight into ways that psychobiological reactivity can be modulated. Non-invasive neuromodulation is one way that responding to stressors may be altered; research into these interventions may provide further insights into the brain circuits that modulate stress reactivity. This review focuses on the effects of acute psychosocial stressors and how neuromodulation might be effective in altering stress reactivity. Although considerable research into stress interventions focuses on treating pathology, it is imperative to first understand these mechanisms in non-clinical populations; therefore, this review will emphasize populations with no known pathology and consider how these results may translate to those with psychiatric pathologies.

Gender operationalisation and stress measurement in research with adolescent males: a scoping review

Aim

Stress measurement in adolescent males is in its relative infancy, which is likely to influence the effectiveness of mental health services for this heterogeneous population. Although evidence suggests the prevalence of mental health difficulties increases during adolescence, the relationship between gender and stress measurement is less explored or understood. This review summarizes findings on gender operationalisation and stress measurement in research with adolescent males.

Methods

For this scoping review, six electronic databases across social and life sciences were searched using terms linked to adolescence, male, stress and research design. Articles were screened, data were extracted, and a narrative synthesis used to characterise studies by research design, adaptation of method for participants’ cultural context, operationalisation of gender, and measurement of stress.

Results

Searches identified 3259 citations, 95 met inclusion criteria and were reviewed. Findings suggest that research on psychological stress in adolescence is a developing field, but one that is currently dominated by Western studies. Furthermore, the results indicate that stress measurement research with adolescent males tends not to make adaptations relative to participants' gender, age, or context.

Conclusions

Stress research with adolescent males is lacking in scope. This review highlights the need for researchers to consider stress responses as more than a biological response, as it has been conceptualised historically. Recommendations for researchers to report research design and protocol more clearly are made to support readers to understand how stress and gender have been operationalised and measured and how this may influence research methodology. Future research should avoid conflating biological differences with gendered experience and demonstrate greater sensitivity to how gender identity may intersect with age and location to perpetuate gendered inequalities.

Music listening and stress recovery in healthy individuals: A systematic review with meta-analysis of experimental studies

Effective stress recovery is crucial to prevent the long-term consequences of stress exposure. Studies have suggested that listening to music may be beneficial for stress reduction. Thus, music listening stands to be a promising method to promote effective recovery from exposure to daily stressors. Despite this, empirical support for this opinion has been largely equivocal. As such, to clarify the current literature, we conducted a systematic review with meta-analysis of randomized, controlled experimental studies investigating the effects of music listening on stress recovery in healthy individuals. In fourteen experimental studies, participants (N = 706) were first exposed to an acute laboratory stressor, following which they were either exposed to music or a control condition. A random-effects meta-regression with robust variance estimation demonstrated a non-significant cumulative effect of music listening on stress recovery g = 0.15, 95% CI [-0.21, 0.52], t(13) = 0.92, p = 0.374. In healthy individuals, the effects of music listening on stress recovery seemed to vary depending on musical genre, who selects the music, musical tempo, and type of stress recovery outcome. However, considering the significant heterogeneity between the modest number of included studies, no definite conclusions may currently be drawn about the effects of music listening on the short-term stress recovery process of healthy individuals. Suggestions for future research are discussed.

Neuroendocrine Response and State Anxiety Due to Psychosocial Stress Decrease after a Training with Subject's Own (but Not Another) Virtual Body: An RCT Study

Previous research involving healthy participants has reported that seeing a moving virtual body from the first person perspective induces the illusion of ownership and agency over that virtual body. When a person is sitting and the virtual body runs, it is possible to measure physiological, behavioral and cognitive reactions that are comparable to those that occur during actual movement. Capitalizing on this evidence, we hypothesized that virtual training could also induce neuroendocrine effects that prompt a decreased psychosocial stress response, as occurs after physical training. While sitting, 26 healthy young adults watched a virtual avatar running for 30 min from the first person perspective (experimental group), while another 26 participants watched the virtual body from the third person perspective (control group). We found a decreased salivary alpha-amylase concentration (a biomarker for the stress response) after the virtual training among the experimental group only, as well as a decreased subjective feeling of state anxiety (but no difference in heart rate). We argue that the virtual illusion of a moving body from the first person perspective can initiate a cascade of events, from the perception of the visual illusion to physiological activation that triggers other biological effects, such as the neuroendocrine stress response.

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.

Combining mental and physical stress: Synergy or interference?

Both cognitive stressors (such as mental arithmetic tasks) and physical stressors (such as the cold pressor test, CP) are among the most widely employed tools in acute stress research, and there is growing evidence for a high degree of stimulus-response specificity, rather than uniformity, in the human stress response. However, little is known about potential synergistic or interfering effects during concurrent administration. While cognitive tasks have been hypothesized to attenuate pain perception during CP, they are also thought to enhance physiological reactivity. Conversely, physical stress might interfere with effective stress induction by cognitive challenges. To address these questions, 56 participants underwent either the CP (3-min ice-water immersion of feet) or a warm-water control condition. In half of the sample, the Paced Auditory Serial Addition Task (PASAT) was performed simultaneously (fully crossed interventions). Salivary cortisol, cardiovascular parameters, and subjective ratings as well as voice pitch (F0) were assessed. Results show that cortisol responses, self-reported pain and subjective arousal were mainly driven by cold exposure, which also led to increased F0. The PASAT incrementally enhanced cardiovascular reactions, but did not affect pain ratings nor cortisol responses to the CP. However, intra-individual concordance between elevated blood pressure and other reactivity measures was enhanced by PASAT administration during the CP. Importantly, performance decrements in the mental-arithmetic task were not associated with diminished stress responses. In conclusion, our results speak against any strong interference when administering cognitive and painful physical stressors simultaneously, pointing rather to specific additive effects, particularly regarding cardiovascular reactivity.

Cardiovascular Responses to Stress Utilizing Anticipatory Singing Tasks

Abstract. Models of psychobiological stress reactivity have a foundation in the measurement of responses to standardized stress tasks. Tasks with anticipatory phases have been proposed as an effective method of stress induction, either as a stand-alone task or replacement constituent elements for existing stressor paradigms. Tasks utilizing singing as a primary stressor have been proposed but the efficacy of these tasks have not been demonstrated while maintaining adherence to a resting/reactivity/recovery framework desirable for heart rate variability (HRV) measurement. This study examines the viability of an anticipatory sing-a-song task as a method for inducing mental stress and examines the utility of the task with specific reference to measures of cardiovascular reactivity and recovery activity, and standard protocols to examine HRV reactivity and recovery. Participants completed a dual task with a math task and an anticipation of singing component. Responses were examined according to a resting/reactivity/recovery paradigm and the findings indicate that the sing-a-song stimulus is effective in generating a stress response. Significant differences in heart rate and self-reported stress between baseline and stressor conditions were detected, with greater magnitude differences between baseline and anticipatory phases. This study has demonstrated the viability of the anticipation of singing as a standardized stressor using cardiovascular measures and has described variants of this task that may be used for repeated measures study designs.

Stress and long-term memory retrieval: a systematic review

Introduction

The experience of stressful events can alter brain structures involved in memory encoding, storage and retrieval. Here we review experimental research assessing the impact of the stress-related hormone cortisol on long-term memory retrieval.

Method

A comprehensive literature search was conducted on PubMed, Web of Science and PsycNet databases with the following terms: “stress,” “long-term memory,” and “retrieval.” Studies were included in the review if they tested samples of healthy human participants, with at least one control group, and with the onset of the stress intervention occurring after the encoding phase and shortly (up to one hour) before the final memory test.

Results

Thirteen studies were included in the qualitative synthesis (N = 962) and were classified according to the time elapsed between stress induction and memory retrieval (stress-retrieval delay), the stress-inducing protocol (stressor), the time of day in which stress induction took place, sex, and age of participants. Most studies induced stress with the Trier Social Stress Test (TSST) between 15 and 25 minutes before the final memory (mostly recall) test and showed significant increases in cortisol levels and memory impairment.

Discussion

The reviewed studies indicate that stress does impair retrieval, particularly when induced with the TSST, in the afternoon, up to 45 minutes before the onset of the final memory test, in healthy young men. These results may inform future research on the impact of stress-induced cortisol surges on memory retrieval.

Bilingual family communication and the impact of language anxiety on cortisol reactivity

OBJECTIVES

The effects of socially evaluated tasks on stress-related behavior and physiology are often studied under artificial experimental conditions, such as contrived public speaking. Less is known about these behavioral and physiological dimensions under more routine conditions, such as family interactions. Here, we tested whether language anxiety during bilingual family conversations correlated to cortisol reactivity and speech patterns and whether family members' ages moderated this effect.

METHODS

Individuals (N = 34) from Spanish-English bilingual families participated in prompted conversations in both languages with their family members and provided saliva that we assayed for cortisol. Participants responded to a survey about language anxiety, and we analyzed their conversations for code switching. We tested whether higher reported anxiety was correlated with increased cortisol reactivity and if participants' age moderated this effect.

RESULTS

Participants' reported language anxiety was not significantly correlated with cortisol reactivity after conversations in either language. However, age significantly moderated the effect of English language anxiety. Among younger individuals, higher English language anxiety was correlated with greater cortisol reactivity after the English conversations. Older individuals did not demonstrate this same pattern. Individuals who code-switched during the English conversations had higher English language anxiety than individuals who did not. Similar patterns were not observed for the Spanish conversations.

CONCLUSIONS

The physiological and verbal responses to English language anxiety may be reflective of the high pressure placed on English use among bilingual families in the U.S., and the greater cortisol reactivity of younger individuals suggests they may face more identity challenging acculturation pressure.

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.

Effect of sugar administration on cortisol responses to acute psychosocial stress

Sugar administration prior acute psychosocial stress exposure was shown to enhance subsequent salivary cortisol responses. However, this finding is based on studies that have administered high doses of glucose to male subjects after long fasting periods. Therefore, in the present study, we investigated the effect of different sugar-containing drinks on acute cortisol stress responses under experimental conditions that are commonplace in stress research and our sample included females and males. Our primary aim was to derive feasible recommendations for a standardized sugar administration in future studies. Of the 103 healthy young participants (49 females, 54 males), 72 were confronted with the Trier Social Stress Test after being randomly assigned to one of three sugar conditions (200 ml of grape juice, a 75 g glucose or a 75 g maltodextrin drink); 31 subjects served as control sample and were exposed to the TSST without sugar administration. Cortisol stress responses were significantly enhanced in the grape juice as well as the glucose group as compared to the control group. Post hoc analysis revealed that this effect seemed to be more pronounced in males than in females. We did not find a significant effect of maltodextrin. Cortisol responder rates in all three experimental groups were higher than in the control group. Our results suggest that, at least in males, the administration of 200 ml of grape juice is sufficient to facilitate HPA axis reactivity and to minimize confounding effects due to interindividual differences in energy availability while being exposed to a laboratory stress paradigm. The unexpected gender-specific effect is of potential relevance and should be scrutinized in future studies.

Mindfulness-based resilience training for aggression, stress and health in law enforcement officers: study protocol for a multisite, randomized, single-blind clinical feasibility trial

BACKGROUND

Law enforcement officers (LEOs) are exposed to significant stressors, elevating their risk for aggression and excessive use of force, as well as mental health consequences, including post-traumatic stress disorder, burnout, alcohol misuse, depression, and suicide. Mindfulness training is a promising approach with high-stress populations that has been shown effective for increasing resilience and improving negative mental health outcomes common among LEOs.

METHOD

Implemented at two sites, the proposed study is designed to establish optimal protocols and procedures for a future full-scale, multisite trial assessing effects of mindfulness-based resilience training versus an attention control (stress management education) and a no-intervention control on physiological, behavioral, and psychological outcomes. To prepare for this future clinical trial, the current study is designed to: enhance efficiency of recruitment, engagement, and retention; optimize laboratory, assessment, and data management procedures; optimize intervention training and ensure fidelity to intervention protocols; and assess participant experience and optimize outcome measures across two sites. Herein, we describe the protocol and methodology of this multisite, randomized, single-blind clinical feasibility trial.

DISCUSSION

The long-term objective of this line of research is to develop an intervention that will reduce violence and increase resilience and mental health among LEOs, as well as yield significant benefits for the communities and residents they serve.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03784846. Registered on 24 December 2018.

No effect of cold pressor test-induced arousal on attentional benefits and costs in an endogenous spatial orienting paradigm

Previous studies have shown that arousal can influence hemispatial bias, suggesting that changes in arousal affect the neural networks involved in spatial attention control. The goal of the present study was to measure the effects of increased arousal on endogenous attentional orienting. We used a Spatial Orienting Paradigm to quantify attentional benefits and costs as measures of attentional orienting and re-orienting responses and exposed participants (N = 25; Experiment 1) to a bilateral feet Cold Pressor Test (CPT) to manipulate arousal. Increases in subjective distress ratings and blood pressure confirmed the effect of CPT on arousal. Although no overall effects of CPT on reaction times in the Spatial Orienting Paradigm were detected, an exploratory analysis of sex-specific effects revealed a left-lateralised decrease in benefits and increase in costs after CPT exposure in the male subsample (N = 11). To confirm these preliminary results, we repeated the experiment in a larger sample (N = 29, all male), but found no effect of CPT on orienting, with moderate to strong evidence in favour of a model excluding all (interaction) effects of CPT exposure (all BF_Incl < 0.3). Instead, our replicated results indicate that voluntary orienting is unaffected by CPT-induced increases of arousal. In the light of previous studies, and keeping in mind the interpretative challenges of null results, we discuss how and why our findings may be specific to endogenous as opposed to exogenous orienting and how arousal could possibly lead to the previously established effects on visuospatial bias without simultaneously affecting orienting and the underlying attention control networks.

Cognitive behavioral therapy, mindfulness, and cortisol habituation: A randomized controlled trial

BACKGROUND

Hypothalamic-pituitary-adrenocortical (HPA) axis dysregulation is associated with disease and may be indexed by poor cortisol habituation (i.e., a failure to show decreased responding with repeated stressor exposure). Thus, stress management training that can enhance HPA axis habituation may benefit health. To date, the effects of Mindfulness Based Stress Reduction (MBSR) and Cognitive Behavioral Therapy (CBT) interventions on HPA axis habituation remain untested. To test the effects of MBSR and CBT on HPA axis habituation, the present study used a parallel arm randomized controlled trial.

METHODS

Healthy adults reporting moderate-to-high stress (n = 138) were randomly assigned to a 6-week MBSR intervention, a 6-week CBT intervention, or Waitlist control group. Post-intervention, participants completed a social-evaluative performance stressor during each of two laboratory visits scheduled 48-h apart. Salivary cortisol was collected pre-stressor, and 25, 35, and 60 min post-stressor onset during each visit. Final analyses included 86 participants who completed procedures up to the first laboratory visit.

RESULTS

Relative to the control condition, both MBSR and CBT groups showed greater cortisol habituation. The MBSR group exhibited marginally greater habituation than the Waitlist group in cortisol samples corresponding to the recovery time points (35 and 60 min post-stressor onset). In contrast, the CBT group showed greater habituation than the Waitlist across all sampling timepoints collected (pre-stressor, 25, 35, and 60 min post-stressor onset). Yet, the CBT group also demonstrated elevated pre-stressor cortisol during the first visit.

CONCLUSIONS

Results suggest that MBSR and CBT interventions promote greater HPA axis habituation relative to no training, but do not reduce overall cortisol output (i.e., across both visits). Observed differences between CBT and MBSR training in relation to cortisol habituation are discussed.

Effects of milk-based phospholipids on cognitive performance and subjective responses to psychosocial stress: A randomized, double-blind, placebo-controlled trial in high-perfectionist men

OBJECTIVES

The aim of this study was to examine the stress-buffering potential of phospholipid (PL) intake on cognitive performance and neuroendocrine and psychological responses under conditions of psychosocial stress in a high-stress vulnerable (perfectionist) sample.

METHODS

Fifty-four high-perfectionist men consumed a 6-wk daily intake of a bovine milk-derived PL (2.7 g/d) or placebo drink in a randomized, double-blind, placebo-controlled, parallel groups design. Working memory, executive control function, and acute physiological/subjective responses to an acute psychosocial stressor were examined before and after the 6-wk PL or placebo intake.

RESULTS

PL intake improved post-stress reaction time performance on an attention-switching task (P = 0.01). No significant attenuation of the salivary cortisol stress response was shown. PL intake significantly increased mid-stress induction energetic arousal (P = 0.03). A non-significant reduction in anticipatory subjective stress was reported after PL intake (P = 0.06). Systolic and diastolic blood pressures (P<0.04 and P = 0.01, respectively) were significantly augmented in the PL condition.

CONCLUSIONS

Dietary intake of bovine milk PLs conferred cognitive performance benefit under conditions of psychosocial stress but failed to moderate cortisol response. Moderation of subjective response to stress exposure may have underpinned this performance protection.

Anticipatory stress associated with functional magnetic resonance imaging: Implications for psychosocial stress research

Stress tasks performed during functional magnetic resonance imaging (fMRI) elicit a relatively small cortisol response compared to stress tasks completed in a traditional behavioral laboratory, which may be due to apprehension of fMRI that elicits an anticipatory stress response. The present study investigated whether anticipatory stress is greater prior to research completed in an MRI environment than in a traditional behavioral laboratory. Anticipatory stress (indexed by cortisol) was greater prior to testing in the MRI environment than traditional behavioral laboratory. Furthermore, anticipation of fMRI elicited a cortisol response commensurate with the response to the stress task in the behavioral laboratory. However, in the MRI environment, post-stress cortisol was significantly lower than baseline cortisol. Taken together, these findings suggest the stress elicited by anticipation of fMRI may lead to acute elevations in cortisol prior to scanning, which may in turn disrupt the cortisol response to stress tasks performed during scanning.

Examining habituation and sensitization across repetitive laboratory stress inductions using the MAST

Reliably eliciting acute stress repeatedly over time is of indispensable value for research into stress vulnerability and for developing interventions aimed at increasing stress resiliency. Here, we evaluated whether the Maastricht Acute Stress Test (MAST), a potent stress protocol that combines physical and psychosocial stress components, can be used to reliably elicit subjective and neuroendocrine stress responses multiple times. Sixty healthy undergraduate participants were exposed to the MAST on three occasions, with intervals of three-weeks and one-month in between sessions. Results showed no significant signs of habituation or sensitization to the MAST in terms of subjective or physiological (salivary alpha-amylase and cortisol) stress reactivity. Fifty-nine percent of the sample displayed a significant physiological stress response (i.e., cortisol) to two MAST exposures and 57% to every MAST exposure. This study demonstrates that the MAST can be used to repeatedly induce significant stress responses.

Key role of 5-HT3 receptors in the nucleus tractus solitarii in cardiovagal stress reactivity

Serotonin plays a modulatory role in central control of the autonomic nervous system (ANS). The nucleus tractus solitarii (NTS) in the medulla is an area of viscerosomatic integration innervated by both central and peripheral serotonergic fibers. Influences from different origins therefore trigger the release of serotonin into the NTS and exert multiple influences on the ANS. This major influence on the ANS is also mediated by activation of several receptors in the NTS. In particular, the NTS is the central zone with the highest density of serotonin₃ (5-HT₃) receptors. In this review, we present evidence that 5-HT₃ receptors in the NTS play a key role in one of the crucial homeostatic responses to acute and chronic stress: inhibitory modulation of the parasympathetic component of the ANS. The possible functional interactions of 5-HT₃ receptors with GABA_A and NK₁ receptors in the NTS are also discussed.