Adaptation to social-evaluative threat: Effects of repeated acceptance and status stressors on cardiovascular reactivity

Social-evaluative threat plays a key role in research on stress, health and related psychophysiological mechanisms such as cardiovascular reactivity (CVR). Social-evaluative threats can activate two broad social motives: striving for status, achievement and influence, and/or striving for acceptance, inclusion, and connection. Prior research emphasizes threats related to status (e.g., task performance) or combined threats to status and acceptance, obscuring their independent effects. Further, because prior research has mostly utilized single stressors, it is not clear if effects of social-evaluative threats involving status and acceptance on CVR persist or adapt quickly over repeated exposures. To address these issues, 139 undergraduates (93 females) were randomly assigned to undergo two repetitions of a stressful role-played interaction with a pre-recorded antagonistic partner under one of four conditions in a factorial design: low evaluative threat, high status threat only, high acceptance threat only, or a combined threat. In a single laboratory session, systolic and diastolic blood pressure (SBP, DBP) and heart rate (HR) were recorded during baseline and two stressor exposures. Task-induced CVR demonstrated significant adaptation across exposures. Both forms of social evaluative threat produced additional CVR, and these differences between high and low social-evaluative threat were generally maintained across exposures. Hence, threats to social status and acceptance have independent and sustained effects on CVR across multiple stressor exposures, even in the context of overall adaptation of cardiovascular responses.

OLD IDEAS, NEW DIRECTIONS: RE-EXAMINING THE PREDICTIVE UTILITY OF THE HEMODYNAMIC PROFILE OF THE STRESS RESPONSE IN HEALTHY POPULATIONS

The 'reactivity hypothesis' has a long and fruitful history in health psychology and behavioural medicine, with elements of its thesis taken as core and others lost in the plethora of research on its utility as a theory of psychosomatic disease. One such thesis is that the underlying hemodynamic profile of the stress response may be particularly revealing when detailing the impact of psychological stress on the development of cardiovascular disease. This paper re-examines old ideas surrounding the hemodynamic profile of the stress response, asking why its health-predictive properties were never fully explored. Further, this paper reviews the evidence that a vascular profile of stress responding may be especially predictive of disease development, particularly in the case of hypertension. In addition, measurement of hemodynamic profile as well as its known psychosocial moderators are reviewed including how examination of patterns of cardiovascular-stress response adaptation may extend the field. This paper highlights that the extension of the reactivity hypothesis to include both hemodynamic profile and patterns of cardiovascular stress-response adaptation may hold much explanatory power in detailing the impact of how stress responding and stress tolerance promotes disease development.

Exhausted Heart Rate Responses to Repeated Psychological Stress in Women With Major Depressive Disorder

Past research links depression and blunted cardiac vagal reactivity to chronic stress. Yet, to our knowledge no experiment investigates heart rate (variability) responses to a repeated laboratory stressor in patients with depression. Repeated exposure may provide valuable information on stress reactivity in depression. Fifty-nine women (30 inpatients diagnosed with depression and 29 matched controls) underwent two consecutive runs of a mental arithmetic stress paradigm consisting of one baseline and two exposures to control, stress, and recovery phases of 5 min each, in a case-control design. Subjective stress and electrocardiography were recorded. Variance of heart rate (HR) and root mean square of successive RR interval differences (RMSSD) were analyzed using linear mixed models. Overall, physiological parameters (HR and RMSSD) and subjective stress showed a strong group effect (all p < 0.001). In both groups, subjective stress and HR increased in response to stress, but the subjective stress levels of patients with depression did not return to baseline levels after the first stressor and for the remainder of the experiment (all p < 0.004 compared to baseline). Patients' HR reactivity responded oppositely: while HR recovered after the first stress exposure, no reactivity was observed in response to the second exposure. These findings may suggest that the often-reported blunted HR/HRV response to stressors results from exhaustion rather than an incapacity to react to stress. The altered HR reactivity could indicate allostatic (over-) load in depression.

Cardiac sympathetic activity during recovery as an indicator of sympathetic activity during task performance

The goals of this research were to analyze cardiac sympathetic recovery patterns and evaluate whether sympathetic cardiac responses to a task challenge can be predicted using residual cardiac activity measured directly after the task (that is, during the recovery period). In two studies (total N = 181), we measured cardiac sympathetic activity, quantified as pre-ejection period and RB interval, during both task performance and the 2-min recovery period following the task. Additional analyses examined effects on the RZ interval. We found that sympathetic recovery from a task was rather quick: Cardiovascular recovery occurred within the first 30 s of the recovery period. Nevertheless, residual cardiac activity during the recovery period had predictive power for task-related cardiac activity. This suggests that sympathetic cardiac activity during recovery may serve as a useful indicator of task-related cardiac sympathetic activity. We discuss the implications of these findings for practical applications and the design of future studies.

Physiological indices of challenge and threat: A data-driven investigation of autonomic nervous system reactivity during an active coping stressor task

We utilized a data-driven, unsupervised machine learning approach to examine patterns of peripheral physiological responses during a motivated performance context across two large, independent data sets, each with multiple peripheral physiological measures. Results revealed that patterns of cardiovascular response commonly associated with challenge and threat states emerged as two of the predominant patterns of peripheral physiological responding within both samples, with these two patterns best differentiated by reactivity in cardiac output, pre-ejection period, interbeat interval, and total peripheral resistance. However, we also identified a third, relatively large group of apparent physiological nonresponders who exhibited minimal reactivity across all physiological measures in the motivated performance context. This group of nonresponders was best differentiated from the others by minimal increases in electrodermal activity. We discuss implications for identifying and characterizing this third group of individuals in future research on physiological patterns of challenge and threat.

Video Games and Stress: How Stress Appraisals and Game Content Affect Cardiovascular and Emotion Outcomes

Although previous studies have found that video games induce stress, studies have not typically measured all salient indicators of stress responses including stress appraisals, cardiovascular indicators, and emotion outcomes. The current study used the Biopsychosocial Model of Challenge and Threat (Blascovich and Tomaka, 1996) to determine if video games induce a cardiovascular stress response by comparing the effects of threat and challenge appraisals across two types of video games that have shown different cardiovascular outcomes. Participants received challenge or threat appraisal instructions, and played a fighting game (Mortal Kombat) or a puzzle game (Tetris). Study outcomes were heart rate variability, systolic and diastolic blood pressure, and positive and negative emotion ratings measured before, during and after gameplay. Results indicated that threat appraisal instructions increased negative emotion ratings and decreased heart rate variability, but not blood pressure, which is an essential marker for cardiovascular stress responses. Increased blood pressure and decreased heart rate variability was associated with fighting game players when compared with the puzzle game players, indicating a cardiovascular stress response; however, fighting game players also reported higher positive emotion ratings. Based on the study findings, video games do not induce stress responses like mental stressors used in previous research, demonstrating that the interactive player experience in video gaming may have more complex effects on stress outcomes. Future research should comprehensively measure biopsychosocial stress indicators and multiple emotional states over time to fully examine the relationship between video games and stress.

Assessing Performance on an Evaluated Speaking Task

Abstract. Coping with social stress involves cognitive perceptions and the activation of several physiological mechanisms. Our main purpose was to examine how psychological factors such as cognitive appraisal, and particularly self-efficacy, may affect psychophysiological reactivity to social stress and young people’s performance on an evaluated speaking task. Thirty-five university students (18 men and 17 women) were exposed to the Trier Social Stress Test (TSST) and a control condition in a counterbalanced order. Self-efficacy, several dimensions of trait anxiety related to social evaluation, and changes in state anxiety were assessed. Additionally, heart rate and heart rate variability (HRV) were analyzed by means of R-R and r-MSSD parameters, respectively. The results indicate that a positive self-assessment of their own ability to overcome a social threat was related to the predominance of vagal tone and better performance. However, cardiac reactivity was not related to the quality of the performance displayed. In addition, some dimensions of trait anxiety, such as cognitive anxiety and test evaluation anxiety, were negatively associated with self-efficacy and performance. These findings emphasize the relevance of self-efficacy, a key component of cognitive appraisal, in explaining psychophysiological reactivity to social stress. Furthermore, they highlight the importance of some personality characteristics, such as social evaluation anxiety, in explaining performance in specifically related stressful situations, regardless of autonomic activation.

Searching for a job: Cardiac responses to acute stress and the mediating role of threat appraisal in young people

Being unemployed and looking for a job has become a source of stress for many people in several European countries. However, little attention has been paid to the impact of this stressful situation on the individuals' psychophysiological stress responses. The aim of this study was to investigate the effect of being an unemployed job seeker on cognitive threat appraisal and cardiac responses to a psychosocial stressor. We exposed a group of unemployed job seekers (N = 42) and a matched group of unemployed non-job seekers (N = 40) to a standardized social stressor in form of job interview, the Trier Social Stress Test. Our results showed that unemployed job seekers manifest lower cardiac responses, along with a lower cognitive threat appraisal, compared to non-job seekers. Moreover, we observed a full mediating role of cognitive threat appraisal on the relationship between being an unemployed job seeker and cardiac responses to stress. These findings reveal that being unemployed and looking for a job has an effect on physiological responses to acute stress, as well as the importance of psychological process related to the situation. These responses might lead to negative health and motivational consequences. Theoretical and practical implications are discussed.

Preejection Period as a Sympathetic Activity Index: a Role of Confounding Factors

In previous studies, one of the systolic time intervals – preejection period (PEP) – was used as an index of sympathetic activity reflecting the cardiac contractility. However, PEP could be also influenced by several other cardiovascular variables including preload, afterload and diastolic blood pressure (DBP). The aim of this study was to assess the behavior of the PEP together with other potentially confounding cardiovascular system characteristics in healthy humans during mental and orthostatic stress (head-up tilt test – HUT). Forty-nine healthy volunteers (28 females, 21 males, mean age 18.6 years (SD=1.8 years)) participated in the study. We recorded finger arterial blood pressure by volume-clamp method (Finometer Pro, FMS, Netherlands), PEP, thoracic fluid content (TFC) – a measure of preload, and cardiac output (CO) by impedance cardiography (CardioScreen® 2000, Medis, Germany). Systemic vascular resistance (SVR) – a measure of afterload – was calculated as a ratio of mean arterial pressure and CO. We observed that during HUT, an expected decrease in TFC was accompanied by an increase of PEP, an increase of SVR and no significant change in DBP. During mental stress, we observed a decrease of PEP and an increase of TFC, SVR and DBP. Correlating a change in assessed measures (delta values) between mental stress and previous supine rest, we found that ΔPEP correlated negatively with ΔCO and positively with ΔSVR. In orthostasis, no significant correlation between ΔPEP and ΔDBP, ΔTFC, ΔCO, ΔMBP or ΔSVR was found. We conclude that despite an expected increase of sympathetic activity during both challenges, PEP behaved differently indicating an effect of other confounding factors. To interpret PEP values properly, we recommend simultaneously to measure other variables influencing this cardiovascular measure.

Using Cognitive Modeling to Study Behavior Moderators: Pre-Task Appraisal and Anxiety

We present a cognitive model of a repeated serial subtraction arithmetic task in the ACT-R cognitive architecture (Anderson & Lebiere, 1998) that is modified to demonstrate how the influence of biobehavioral effects on cognition (sometimes called behavioral moderators) can be studied through a combination of cognitive modeling experimental psychology, and physiological psychology techniques.

The effect of stress on learning in surgical skill acquisition

BACKGROUND

An excessive level of stress and anxiety in medical education can have a negative impact on learning. In particular, the interaction between attending surgeons and trainees in the operating room could induce stress on trainees that is counterproductive, especially if the teaching style or feedback is unduly harsh or critical.

AIM

To characterize the effects of stress resulting from attending-trainee interaction during surgical skill acquisition.

METHODS

Forty medical students learned to perform the FLS pattern-cutting task for the first time in one of four scenarios. In the control condition, no mentor was present. In the three experimental conditions, participants were observed, encouraged, or criticized by an expert surgeon.

RESULTS

Task performance, as well as physiological and subjective indicators of stress, were measured. Taking both speed and accuracy into account, participants who were criticized performed the worst on the task, and those who were encouraged performed best. Physiological and subjective measures indicated that the criticized participants experienced the highest level of stress and anxiety.

CONCLUSION

Even though providing constructive criticism to trainees is inevitable during the course of teaching, an exceedingly critical and negative mentoring style by attending physicians could be detrimental to trainees' acquisition of surgical skills.

Physiological responses to repeated stress in individuals with high and low trait resilience

This study examined individual differences in trait resilience in physiological recovery from, and physiological habituation to, repeated stress (i.e. public speaking). Eighty-two college students were categorized as either high (n=40) or low (n=42) on trait resilience, based on the scores of the Connor-Davidson Resilience Scale (CD-RISC). Subjective and physiological data were collected from participants across seven laboratory stages: baseline, stress anticipation 1, stress 1, post-stress 1, stress anticipation 2, stress 2, and post-stress 2. Results indicated that high-trait-resilient participants exhibited more complete heart rate (HR), systolic and diastolic blood pressure (SBP, DBP) recovery from the first and second stress anticipation exposures as compared to low-trait-resilient participants. High-trait-resilient participants demonstrated higher resting respiratory sinus arrhythmia (RSA) coupled with more complete RSA recovery from the first and second stress anticipation exposures as compared to their low-trait-resilient counterparts. Moreover, high-trait-resilient participants exhibited pronounced SBP and DBP habituation across two successive stress anticipation exposures, with greater decreases in SBP and DBP reactivity to recurrent stress anticipation as compared to the low-trait-resilient participants. These findings suggest an adaptive physiological response pattern to recurrent stress in high-trait-resilient individuals.

Nervous Facilitation in Cardiodynamic Response of Exercising Athletes to Superimposed Mental Tasks: Implications in Depressive Disorder

Introduction : Motor commands to perform exercise tasks may also induce activation of cardiovascular centres to supply the energy needs of the contracting muscles. Mental stressors per se may also influence cardiovascular homeostasis. We investigated the cardiovascular response of trained runners simultaneously engaged in mental and physical tasks to establish if aerobically trained subjects could develop, differently from untrained ones, nervous facilitation in the brain cardiovascular centre. Methods : Cardiovascular responses of 8 male middle-distance runners (MDR), simultaneously engaged in mental (colour-word interference test) and physical (cycle ergometer exercise) tasks, were compared with those of 8 untrained subjects. Heart rate, cardiac (CI) and stroke indexes were assessed by impedance cardiography while arterial blood pressures were assessed with a brachial sphygmomanometer. Results : Only in MDR simultaneous engagement in mental and physical tasks induced a significant CI increase which was higher (p<0.05) than that obtained on summing CI values from each task separately performed. Conclusion : Aerobic training, when performed together with a mental effort, induced a CI oversupply which allowed a redundant oxygen delivery to satisfy a sudden fuel demand from exercising muscles by utilizing aerobic sources of ATP, thus shifting the anaerobic threshold towards a higher work load. From data of this study it may also be indirectly stated that, in patients with major depressive disorder, the promotion of regular low-intensity exercise together with mental engagement could ameliorate the perceived physical quality of life, thus reducing their heart risk associated with physical stress.

Cardiorespiratory Information Dynamics during Mental Arithmetic and Sustained Attention

An analysis of cardiorespiratory dynamics during mental arithmetic, which induces stress, and sustained attention was conducted using information theory. The information storage and internal information of heart rate variability (HRV) were determined respectively as the self-entropy of the tachogram, and the self-entropy of the tachogram conditioned to the knowledge of respiration. The information transfer and cross information from respiration to HRV were assessed as the transfer and cross-entropy, both measures of cardiorespiratory coupling. These information-theoretic measures identified significant nonlinearities in the cardiorespiratory time series. Additionally, it was shown that, although mental stress is related to a reduction in vagal activity, no difference in cardiorespiratory coupling was found when several mental states (rest, mental stress, sustained attention) are compared. However, the self-entropy of HRV conditioned to respiration was very informative to study the predictability of RR interval series during mental tasks, and showed higher predictability during mental arithmetic compared to sustained attention or rest.

Multi-time scale perspective in analyzing cardiovascular data

Cardiovascular dynamic and variability data are commonly used in experimental protocols involving cognitive challenge. Usually, the analysis is based on a sometimes more and sometimes less well motivated single specific time resolution ranging from a few seconds to several minutes. The present paper aimed at investigating in detail the impact of different time resolutions of the cardiovascular data on the interpretation of effects. We compared three template tasks involving varying types of challenge, in order to provide a case study of specific effects and combinations of effects over different time frames and using different time resolutions. Averaged values of hemodynamic variables across an entire protocol confirmed typical findings regarding the effects of mental challenge and social observation. However, the hemodynamic response also incorporates transient variations in variables reflecting important features of the control system response. The fine-grained analysis of the transient behavior of hemodynamic variables demonstrates that information that is important for interpreting effects may be lost when only average values over the entire protocol are used as a representative of the system response. The study provides useful indications of how cardiovascular measures may be fruitfully used in experiments involving cognitive demands, allowing inferences on the physiological processes underlying the responses.

The biopsychosocial model of stress in adolescence: self-awareness of performance versus stress reactivity

Extensive research among adults supports the biopsychosocial (BPS) model of challenge and threat, which describes relationships among stress appraisals, physiological stress reactivity, and performance; however, no previous studies have examined these relationships in adolescents. Perceptions of stressors as well as physiological reactivity to stress increase during adolescence, highlighting the importance of understanding the relationships among stress appraisals, physiological reactivity, and performance during this developmental period. In this study, 79 adolescent participants reported on stress appraisals before and after a Trier Social Stress Test in which they performed a speech task. Physiological stress reactivity was defined by changes in cardiac output and total peripheral resistance from a baseline rest period to the speech task, and performance on the speech was coded using an objective rating system. We observed in adolescents only two relationships found in past adult research on the BPS model variables: (1) pre-task stress appraisal predicted post-task stress appraisal and (2) performance predicted post-task stress appraisal. Physiological reactivity during the speech was unrelated to pre- and post-task stress appraisals and to performance. We conclude that the lack of association between post-task stress appraisal and physiological stress reactivity suggests that adolescents might have low self-awareness of physiological emotional arousal. Our findings further suggest that adolescent stress appraisals are based largely on their performance during stressful situations. Developmental implications of this potential lack of awareness of one's physiological and emotional state during adolescence are discussed.

A sigh following sustained attention and mental stress: effects on respiratory variability

Normal breathing consists of considerable correlated variability (parameters of subsequent breaths are correlated) and some random variability. Emotional and attentive states alter normal breathing variability, which can be restored by a sigh. The present study aimed to investigate the effects of mental arithmetic and sustained attention on respiratory variability. In addition, the effect of a spontaneous sigh following both conditions was examined, compared to an instructed sigh and a control maneuver. Mental arithmetic and sustained attention were characterized by decreased correlated and total breathing variability, respectively. A spontaneous sigh restored correlated variability. An instructed sigh restored correlated variability following mental arithmetic, and increased total variability following sustained attention. These results suggest that a spontaneous sigh and an instructed sigh, when physiologically appropriate, restore respiratory variability influenced by stress or attention.

The influence of neuroticism, extraversion and openness on stress responses

The present research moved beyond focusing on negative dispositions to investigate the influence of positive aspects of personality, namely extraversion and openness, on stress responses including appraisals, affect and task performance. Challenge appraisals occur when stressor demands are deemed commensurate with coping resources, whereas threat appraisals occur when demands are believed to outweigh coping resources. We examined the unique influence of personality on stress responses and the mediating role of appraisals. Personality was assessed, and then participants (N = 152) were exposed to a validated math stressor. We found unique effects on stress responses for neuroticism (high threat and negative affect and low positive affect), extraversion (high positive and low negative affect) and openness (high positive and low negative effect and better performance). Mediation analyses revealed that neuroticism indirectly worsened performance, through threat appraisals, and that openness indirectly increased positive affect through lower threat. These findings highlight the importance of investigating multiple aspects of personality on stress responses and provide an avenue through which stress responses can be changed-appraisals. Only by more broad investigations can interventions be tailored appropriately for different individuals to foster stress resilience.

Alpha-adrenergic receptor gene polymorphisms and cardiovascular reactivity to stress in Black adolescents and young adults

Cardiovascular reactivity to stress and α-adrenergic receptor (α-AR) function may contribute to the development of hypertension. As Black Americans have an increased risk of hypertension, we evaluated associations between α(1A) -AR (Arg492Cys), α(2A) -AR (-1291C/G), and α(2B) -AR (Ins/Del301-303) gene variants and cardiovascular reactivity in 500 normotensive Black youth. Heart rate, preejection period, total peripheral resistance, and blood pressure were measured during cold and psychological stress. The Arg492Cys polymorphism in the α(1A) -AR gene was associated with heart rate reactivity to stress, but the association depended on sex. The -1291C/G promoter polymorphism in the α(2A) -AR gene was associated with vascular reactivity to stress; vasoconstriction increased as a linear function of the number of copies of the variant G allele. Thus, specific associations emerged between genetic variations in α-Ars and cardiovascular reactivity in young Blacks.

The effect of competition on heart rate during kart driving: A field study

Background

Both the act of competing, which can create a kind of mental stress, and participation in motor sports, which induces physical stress from intense g-forces, are known to increase heart rate dramatically. However, little is known about the specific effect of competition on heart rate during motor sports, particularly during four-wheel car driving. The goal of this preliminary study, therefore, was to investigate whether competition increases heart rate under such situations.

Findings

The participants drove an entry-level formula kart during two competitive races and during solo driving against the clock while heart rate and g-forces were measured. Analyses showed that heart rate values during the races (168.8 beats/min) were significantly higher than those during solo driving (140.9 beats/min) and rest (75.1 beats/min).

Conclusions

The results of this preliminary study indicate that competition heightens heart rate during four-wheel car driving. Kart drivers should be concerned about maintaining good health and developing physical strength.

Masked affective stimuli moderate task difficulty effects on effort-related cardiovascular response

This experiment investigated the combined effect of masked affective stimuli and task difficulty on effort-related cardiovascular response. Cardiovascular reactivity (ICG, blood pressure) was recorded during a baseline period and performance of an easy or difficult attention task in which participants were exposed to masked sad vs. happy facial expressions. As expected, participants in the sad-faces/easy and happy-faces/difficult conditions showed stronger sympathetic nervous system discharge to the heart and vasculature--shorter preejection period, higher systolic blood pressure--indicating more effort than participants in the sad-faces/difficult and happy-faces/easy conditions. Total peripheral resistance reacted similarly as preejection period and systolic blood pressure. The findings are compatible with the effects of consciously experienced affect on effort-related cardiovascular response.

Sigh rate and respiratory variability during mental load and sustained attention

Spontaneous breathing consists of substantial correlated variability: Parameters characterizing a breath are correlated with parameters characterizing previous and future breaths. On the basis of dynamic system theory, negative emotion states are predicted to reduce correlated variability whereas sustained attention is expected to reduce total respiratory variability. Both are predicted to evoke sighing. To test this, respiratory variability and sighing were assessed during a baseline, stressful mental arithmetic task, nonstressful sustained attention task, and recovery in between tasks. For respiration rate (excluding sighs), reduced total variability was found during the attention task, whereas correlated variation was reduced during mental load. Sigh rate increased during mental load and during recovery from the attention task. It is concluded that mental load and task-related attention show specific patterns in respiratory variability and sigh rate.

Take a deep breath: the relief effect of spontaneous and instructed sighs

Spontaneous sighing is related to subjective relief of negative emotional states. Whether this also applies to instructed sighing is not known. The present study aimed to investigate sEMG and respiratory variability (1) during recovery from mental stress with and without an instructed sigh; (2) before and after spontaneous sighs throughout the experiment. A spontaneous sigh was preceded by increasing sEMG and increasing random respiratory variability, and followed by decreasing sEMG and increased structured correlated respiratory variability. Following an instructed sigh, a smaller reduction in sEMG and an increase in random respiratory variability during recovery from mental stress were observed. Thus, a spontaneous sigh seemed to induce relief. An instructed sigh appeared to inhibit recovery from mental stress.

Beta-adrenergic receptor gene polymorphisms and cardiovascular reactivity to stress in Black adolescents and young adults

Cardiovascular reactivity to stress and beta-adrenergic receptor (beta-AR) function may contribute to the development of hypertension. As Black Americans have an increased risk of hypertension, we evaluated associations between beta(1)-AR (Arg389Gly) and beta(2)-AR (Arg16Gly, Gln27Glu) gene variants and cardiovascular reactivity in 500 Black youth. Heart rate, preejection period, total peripheral resistance, and blood pressure reactivity were measured during cold and psychological stress. The Arg389Gly polymorphism in the beta(1)-AR was associated with preejection period reactivity in males but not in females. The Arg16Gly polymorphism in the beta(2)-AR was associated with diastolic blood pressure reactivity only during video game stress. An association between the Gln27Glu polymorphism in the beta(2)-AR and vascular reactivity depended on sex. Thus, specific patterns of associations emerged between genetic variations in beta-ARs and cardiovascular reactivity in young Blacks.

Effects of mental stress on autonomic cardiac modulation during weightlessness

Sustained weightlessness affects all body functions, among these also cardiac autonomic control mechanisms. How this may influence neural response to central stimulation by a mental arithmetic task remains an open question. The hypothesis was tested that microgravity alters cardiovascular neural response to standardized cognitive load stimuli. Beat-to-beat heart rate, brachial blood pressure, and respiratory frequency were collected in five astronauts, taking part in three different short-duration (10 to 11 days) space missions to the International Space Station. Data recording was performed in supine position 1 mo before launch; at days 5 or 8 in space; and on days 1, 4, and 25 after landing. Heart rate variability (HRV) parameters were obtained in the frequency domain. Measurements were performed in the control condition for 10 min and during a 5-min mental arithmetic stress task, consisting of deducting 17 from a four-digit number, read by a colleague, and orally announcing the result. Our results show that over all sessions (pre-, in-, and postflight), mental stress induced an average increase in mean heart rate (Δ7 ± 1 beats/min; P = 0.03) and mean arterial pressure (Δ7 ± 1 mmHg; P = 0.006). A sympathetic excitation during mental stress was shown from HRV parameters: increase of low frequency expressed in normalized units (Δ8.3 ± 1.4; P = 0.004) and low frequency/high frequency (Δ1.6 ± 0.3; P = 0.001) and decrease of high frequency expressed in normalized units (Δ8.9 ± 1.4; P = 0.004). The total power was not influenced by mental stress. No effect of spaceflight was found on baseline heart rate, mean arterial pressure, and HRV parameters. No differences in response to mental stress were found between pre-, in-, and postflight. Our findings confirm that a mental arithmetic task in astronauts elicits sympathovagal shifts toward enhanced sympathetic modulation and reduced vagal modulation. However, these responses are not changed in space during microgravity or after spaceflight.

Gender and stress: differential psychophysiological reactivity to stress reexposure in the laboratory

Research has shown that women are more prone to the development of depression and anxiety disorders throughout their lifetimes. Stress reactivity and adaptation to repeated stressors have been linked to depression and anxiety, but studies examining gender differences in psychophysiological responses to repeated stressors are very limited. This study examined gender differences in response to initial and repeated exposure to a laboratory stressor as well as potential mechanisms for these differences. Participants viewed a Holocaust video on two occasions with a 2-day interval between sessions. Self reported negative affect and cardiovascular reactivity were recorded at both sessions. Although gender differences were not found following initial exposure, women exhibited significantly greater heart rate (HR) and negative affect (NA) reactivity to the second exposure as compared to men. Women also reported significantly greater intrusive thoughts and avoidance after the first exposure than men, but these were not found to be significant mediators. The findings indicate that women may be more vulnerable to repeated stress exposures compared to men suggesting sensitization. The implications of our findings and suggestions for future research are discussed.

Reliability of cardiovascular reactivity to stress: Internal consistency

Research on the reliability of cardiovascular reactivity has focused on temporal stability and intertask consistency with only modest results. The present study evaluated the internal consistency reliability of cardiovascular reactivity in three large samples of adolescents and young adults (N=326, 136, and 142). Impedance cardiographic and blood pressure measures were recorded at rest and during standard laboratory stress tasks (math, video game, cold pressor). The reliability of cardiovascular reactivity within tasks, as assessed by Cronbach's alpha coefficient of internal consistency, ranged from alpha=.83 to .96 for 4-min to 5-min math tasks, and alpha=.65 to .94 for 3-min video game and cold pressor tasks. Although highly reliable within tasks, cardiovascular reactivity was less reliable across tasks, even within a single testing session. Possible reasons for the discrepancy between internal consistency and intertask consistency are discussed.

Effects of social anxiety and evaluative threat on cardiovascular responses to active performance situations

This study investigated the joint influence of trait social anxiety and evaluative threat on psychological and cardiovascular responses to active coping situations. Fifty-two normotensive female students characterized as either high or low in trait social anxiety performed a mental arithmetic task and a speech task requiring persuasive behavior in a context of high or low evaluative threat. Trait social anxiety exerted a substantial influence on cardiovascular reactivity. High socially anxious individuals overall exhibited greater heart rate reactivity. For systolic and diastolic blood pressure enhanced reactivity of socially anxious individuals was confined to low evaluative threat. At high levels of evaluative threat no group differences were observed due to somewhat attenuated reactivity in high compared to low socially anxious individuals. Cognitive appraisals and affective arousal were not found to mediate the effects of social anxiety on cardiovascular reactivity. Results were attributed to differences in effort expenditure rather than experienced anxiety.

Hemodynamic profile, compensation deficit, and ambulatory blood pressure

This study hypothesized that physiologically grounded patterns of hemodynamic profile and compensation deficit would be superior to traditional blood pressure reactivity in the prediction of daily-life blood pressure. Impedance cardiography-derived measures and beat-to-beat blood pressure were monitored continuously in 45 subjects during baseline and four tasks. Ambulatory blood pressure measures were obtained combining data from one work day and one off day. The mediating effects of gender and family history of hypertension were considered. Only gender was significantly associated with hemodynamic profile. Regression analysis indicated that typical reactivity measures failed to predict everyday life blood pressure. After controlling for gender and baseline blood pressure, hemodynamic patterns during specific tasks proved to be strong predictors, overcoming limitations of previous reactivity models in predicting real-life blood pressure.

Effects of trait dominance on psychological and cardiovascular responses to social influence attempts: the role of gender and partner dominance

This study investigated the influence of trait dominance on cardiovascular reactivity to and recovery from a dyadic interaction task requiring active social influence attempts. Thirty-six male and 36 female normotensive high-school students characterized as either high or low in trait dominance engaged in a mixed-gender discussion with a high or low dominant partner. Trait dominance substantially influenced cardiovascular reactivity to the interpersonal stressor. High dominant participants displayed higher increases in systolic blood pressure (SBP) and pulse pressure (PP), but lower diastolic elevations than low dominant participants. The difference in diastolic reactivity was particularly pronounced in females. Recovery from stress was influenced by level of partner dominance. Participants interacting with a dominant partner showed delayed diastolic recovery. The observed cardiovascular effects seem to reflect greater task engagement and efficient coping in dominant subjects. Group differences in cognitive task appraisals and affective experiences are consistent with this interpretation. Differences in psychological responding were not found to mediate the relation between trait dominance and cardiovascular responses, however.

Cardiac reactivity is associated with changes in negative emotion in 24-month-olds

Despite the call for multilevel observation of negative affect, including multiple physiological systems, too little empirical research has been conducted in infants and young children, and physiology-affect associations are not consistently reported. We examined changes in heart rate, respiratory sinus arrhythmia, and preejection period in 24-month-olds across four increasingly challenging, emotion-eliciting tasks. We predicted that changes in cardiac reactivity would be systematically related to changes in negative affect. Results largely support the predictions with one important exception. With increasing distress across the tasks, HR increased and RSA decreased. However, no significant changes in PEP were observed. HR was associated with negative affect during all tasks, and changes in HR were related to changes in negative affect. PEP and negative affect were associated, but only marginally so. Within-subject analyses confirmed the predicted associations. Finally, the associations between physiology and negative affect were different for boys and girls. We discuss these results in the context of implications for future research on cardiac-affect associations in young children.

Cardiovascular reactivity and adaptation to recurrent psychological stress: Replication and extension

We analyzed the effects of evaluative observation and baseline duration on cardiovascular reactivity and adaptation to recurrent psychological stress. Cardiovascular reactivity to mental arithmetic stress was assessed in college men and women (N=224) during two pretest tasks, a test task, and a posttest task. Participants were assigned randomly in a 2 x 2 design to manipulations of baseline duration before the test task (4 min vs. 12 min) and evaluative observation during the test task (observed vs. control). Repeated exposure to stress attenuated cardiac but not vascular reactivity. Evaluative observation disrupted cardiac adaptation, resulting in a resurgence of beta-adrenergic cardiac reactivity during the test task. Cardiac adaptation resumed fully during the posttest task. Baseline duration had no effect on reactivity. The results replicate and extend previous work, and support the dual process theory of habituation and sensitization.

Acute threat to the social self: shame, social self-esteem, and cortisol activity

OBJECTIVE

Our Social Self Preservation Theory asserts that situations which threaten the "social self" (ie, one's social value or standing) elicit increased feelings of low social worth (eg, shame), decrements in social self-esteem, and increases in cortisol, a hormone released by the hypothalamic-pituitary-adrenal axis. To test our theoretical premise, cognitive, emotional, and physiological responses to the performance of laboratory stressor tasks were compared in participants who performed these tasks in the presence or absence of social-self threat.

METHODS

Pre- and poststressor emotion, self-esteem, heart rate, blood pressure, and salivary cortisol were compared in 81 participants randomly assigned to complete speech and mental arithmetic stress tasks with social evaluation present (n = 41) or absent (n = 40).

RESULTS

As hypothesized, participants in the social evaluation condition exhibited greater increases in shame and greater decrements in social self-esteem. Other psychological states (eg, anxiety, performance self-esteem) did not show differential changes as a function of the social context. Salivary cortisol increased in social evaluation condition participants but did not increase in participants who performed the same tasks in the absence of social evaluation. Cortisol increases were greater in participants who experienced greater increases in shame and greater decreases in social self-esteem under social-self threat.

CONCLUSION

Threat to the social self is an important elicitor of shame experience, decreases in social self-esteem and cortisol increases under demanding performance conditions. Cortisol changes may be specifically tied to the experience of emotions and cognitions reflecting low self-worth in this context.

Relation of cognitive appraisal to cardiovascular reactivity, affect, and task engagement

The relation of primary cognitive appraisals to cardiovascular reactivity, affect, task engagement, and perceived stress was examined in 56 men (ages 18-29). Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate, preejection period, stroke index, cardiac index, and total peripheral resistance were assessed at rest and during performance of a computerized mental arithmetic task. Extending on prior investigations, threat and challenge appraisals were assessed independently from one another and from secondary appraisals. Positive and negative affect, task engagement, and levels of perceived stress were also assessed. Results indicated that threat (R2 =.08, p =.01), challenge (R2 =.14, p =.003), and their interaction (R2 =.11, p =.006) independently predicted DBP reactivity; DBP responses were greatest among participants with a high threat/low challenge pattern of appraisal. Threat appraisals predicted greater negative affect (R2 =.32) and perceived stress (R2 =.48), whereas challenge appraisals were related to greater positive affect (R2 =.44) and task engagement (R2 =.40, ps <.0001). Greater positive affect was correlated with increased SBP and DBP reactivity, and greater levels of task engagement with increased DBP response (ps < or = .002). Results suggest that primary cognitive appraisals are more potent predictors of affect and task engagement than cardiovascular reactivity.

Sympathoadrenergic mechanisms in reduced hemodynamic stress responses after exercise

PURPOSE

This study examines the acute effects of moderate aerobic exercise on 1) hemodynamic and sympathetic activity during behavioral stress and 2) beta-adrenergic receptor responsivity in a biracial sample of 24 sedentary adults.

METHODS

Before and after exercise, blood pressure (BP), impedance-derived cardiovascular measures, and plasma norepinephrine (NE) and epinephrine (EPI) were assessed during mental arithmetic and active speech tasks, and beta-adrenergic receptor responsivity was assessed using a standard isoproterenol challenge procedure.

RESULTS

After exercise, BP, NE, and EPI responses to stress were reduced (0.0001 < P < 0.08), preejection period (PEP) was elongated (P < 0.0001), and beta(1)- and beta(2)-receptor responsivity (P < 0.02) was enhanced. Approximately 65% of the prepost exercise mean arterial pressure response difference could be accounted for by changes in sympathetic factors, with change in NE and PEP being the single best predictors.

CONCLUSIONS

Reduced BP responses to stress after acute exercise are strongly linked to a decrease in sympathetic drive, as evidenced by reduced NE responses and elongation of the PEP. Coincident with this overall dampening of the hemodynamic response to stress, increases in cardiac and vascular beta-adrenergic receptor responsivity occur. These findings may have important implications for future translational studies that seek to articulate the mechanisms through which regular aerobic exercise reduces the risks of hypertensive and coronary heart disease.

A thermodynamic model of the sympathetic and parasympathetic nervous systems

In light of the nonequilibrium thermodynamics by I. Prigogine, the autonomic nervous system as a whole may be viewed as a dissipative structure progressively assembled in the course of evolution, plastically and rhythmically interfaced between forebrain, internal and external environments, to regulate energy, matter and information exchanges. In the present paper, this hypothesis is further pursued to verify whether the two main divisions of the autonomic nervous system, the sympathetic and parasympathetic systems, may support different types of exchange with the external environment. Previous data from hypothalamic stimulation experiments, studies of locus coeruleus function and available data on behavioral functional organization indicate that (1) tight engagement with the external environment, (2) high level of energy mobilization and utilization and (3) information mainly related to exteroceptive sensory stimulation characterize a behavioral prevalence of sympathoadrenal activation. On the other hand, (1) disengagement from the external environment, (2) low levels of internal energy and (3) dominance of proprioceptive information characterize a behavioral prevalence of vagal tone. Behavioral matter exchanges such as feeding, drinking, micturition and defecation are equally absent at the extreme of sympathoadrenal and vagally driven behaviors. The autonomic nervous system as a whole is genetically determined, but the sympathoadrenal system has been mainly designed to organize the visceral apparatus for an action to be performed by the biological system in the external environment and to deal with the novelty of task and of the environment, while the functional role of the parasympathetic is to prepare the visceral apparatus for an action to be performed by the biological system on itself, for recovery and self-protection (homeostasis), and is reinforced by repetition of phylo- and ontogenetically determined patterns. The available clinical data further support this interpretation indicating that an increased sympathetic and a decreased vagal tone may represent a consistent risk factor for cardiovascular diseases.

Cardiovascular reactivity to psychological challenge: conceptual and measurement considerations

OBJECTIVE AND METHODS

This article is a selective review of recent findings bearing on the conceptualization and measurement of cardiovascular reactivity to psychological challenge, with a focus on several issues relevant to the reliability, content validity, construct validity, and criterion validity of these measures.

RESULTS AND CONCLUSIONS

With respect to reliability, use of standardized task demands and aggregated scores are associated with enhanced short-term reliability, but the long-term reliability of cardiovascular reactivity has not been sufficiently documented. With respect to content validity, existing evidence suggests that "vascular" or "cardiac" tasks may evoke responses that reflect similar distributions of individual difference, whereas associations between responses to "physical" and "psychological" tasks are modest. The evidence is not clear at present with respect to the importance of including affective or interpersonal stimuli as part of trait reactivity assessments. With respect to construct validity, existing data show that cardiovascular reactivity to psychological challenge is largely independent of standard measures of autonomic function. With respect to criterion validity, recent studies point to a number of methodological limitations that may have restricted our ability to detect lab-to-life generalizability of reactivity measures in the past. Continued progress in understanding and measuring reactivity as an individual difference dimension is essential in helping us to evaluate emerging evidence examining the relationship between reactivity and disease risk.

Consistency of hemodynamic responses to cold stress in adolescents

Laboratory research on hypertension often is performed with cold stress to elicit vasoconstriction and increases in blood pressure. Several studies have shown that cardiovascular responses to the cold pressor test predict the development of hypertension. We extended this research by comparing cardiovascular responses to a traditional forehead cold pressor test and a naturalistic whole-body cold exposure. We evaluated blood pressure and impedance cardiographic measures of cardiac output and total peripheral resistance in healthy black (n=69) and white (n=47) adolescents (mean age, 14.7 years) during forehead cold pressor (3 degrees C to 4 degrees C) and passive whole-body exposure to a cold chamber (8 degrees C to 10 degrees C). Both tasks elicited increases in vascular resistance and blood pressure, but forehead cold elicited an increase in cardiac output, whereas whole-body cold elicited a decrease in cardiac output (P<0.05). Consistent with previous research, there was a tendency toward greater vasoconstrictive reactivity to cold stress in blacks than in whites, particularly during whole-body cold exposure (P<0.05). Cardiovascular reactivity correlated significantly between tasks, but substantial intertask consistency occurred only for cardiac and vascular reactivity in male subjects (r>0.30) but not in female subjects (r<0.15). These gender differences might reflect diminished adrenergic receptor function in female subjects. We conclude that whole-body cold exposure offers a viable, relatively naturalistic alternative to traditional cold pressor tests for the assessment of cardiovascular reactivity.