Classification of individual differences in cardiovascular responsivity: The contribution of reactor type controlling for race and gender

Classification of 150 normotensive or mildly hypertensive men and women into myocardial, vascular, or mild reactors was accomplished using a regression-based approach. The method was based on the participants’ cardiac output (CO) and total peripheral resistance (TPR) reactivity to the speech presentation task. This task purportedly can elicit both myocardial and vascular responses. Cut-scores were based on the v-intercept from the linear regression of the CO reactivitv on TPR reactivity and vice versa. A greater percentage of Black men were classified as vascular responders as compared to Black women and White participants. Groups were found to differ on cardiovascular reactivity to the speech preparation, cold pressor, and mirror tracing tasks in predictable ways, after controlling for gender and ethnicity. Groups were also differentiated by ambulatory blood pressure and hypertensive status. The study supports the classification of homogeneous groups of participants based on the relative extent to which myocardial or vascular mechanisms dominate the reactivity to stress.     

Comparison of cardiac versus vascular reactors and ethnic groups in plasma epinephrine and norepinephrine responses to stress

This study examined differences in plasma epinephrine (EPI) and norepinephrine (NOREPI) responses to stressors in 67 healthy African-American and Caucasian American men and women of the ages 18 to 49. Subjects were divided into three groups: (a) those who showed high blood pressure (BPI responses to stress associated with consistently high cardiac output (CO) increases with no substantial increases in total peripheral resistance (TPR), labeled cardiac reactors: (b) those with equally high BP increases associated with consistently higher TPR increases and lesser CO increases. labeled vascular reactors; (c) those who showed mixed hemodynamic responses or were low BP reactors. Ethnic and gender group differences in EPI and NOREPI responses were also examined. Cardiac reactors, vascular reactors and mixed + low reactors did not differ in EPI or NOREPI levels at baseline. During stressors, cardiac reactors showed greater increases in plasma EPI than vascular reactors or others during math, reaction time, and passive and active speech tasks: they also showed a weak trend toward greater NOREPI increases during these challenges as well. No differences were seen during the cold pressor: this stressor evoked the least change in EPI of all tasks, whereas the active speech elicited the greatest increases in both EPI and NOREPI of all tasks. Vascular reactors did not differ from mixed + low reactors in EPI or NOREPI reactivity, and men and women did not differ in EPI or NOREPI reactivity to any task. In contrast, Black subjects showed greater increases in NOREPI levels across all stressors compared to White subjects. These findings have implications for investigations of the role of sympathetic nervous system activity in the pathogenesis of hypertension in both African-American and Caucasian American populations.     

Hostility, emotional expression, and hemodynamic responses to laboratory stressors: Reactivity attenuating effects of a tendency to express emotion interpersonally

The present study examined the interactive effects of hostility and a predisposition towards emotional expression or suppression in interpersonal situations. We also attempted to partially replicate findings from a recent investigation which provided evidence of lower myocardial and greater vascular responses in high-hostile relative to low-hostile individuals. Undergraduate students (n = 99) participated in a protocol consisting of rest periods, speech preparation and presentation, a social-evaluative mental arithmetic task, and a stress interview. After classifying participants into high/low hostility by high/low interpersonal emotional expression groups using median-splits, high-hostile individuals showed lower HR and SBP responses to speech preparation and reported greater threat appraisal and negative affect than low-hostile participants. High-hostile interpersonal expressors and male interpersonal expressors displayed lower DBP and TPR reactivity, respectively, than high-hostile or male suppressors. High-hostile expressors also reported lower levels of positive affect than high-hostile suppressors, and expressors reported lower threat appraisals than suppressors, irrespective of hostility. Findings are discussed in terms of an absence of conflict or ambivalence over interpersonal emotional expression for high-hostile expressors and are suggestive of potential health benefits of expressing emotion interpersonally for at-risk groups.     

Establishing the validity of a novel passive stress task

Laboratory tasks used to elicit a cardiovascular stress response in the laboratory can involve either active or passive coping. However, in previous work, passive stress tasks often incorporate a distinct physical stress element, such as the handgrip or cold pressor task, meaning observed changes in cardiovascular parameters may be the result of the physical element of the stressor rather than truly reflecting psychological stress. The present study aimed to establish the validity of a psychological passive stressor; one more analogous to active tasks than those previously employed in laboratory studies. Twenty-six young, healthy adults completed a speech task in the laboratory following a resting baseline period. Twelve months later, they were invited back to the laboratory and watched the video recording of their speech. Analyses confirmed that while both tasks elicited significant SBP and DBP change (all ps < .001), only the active task was associated with HR and CO reactivity (both ps < .001), while only the passive task was associated with TPR reactivity (p = .028). Furthermore, the passive stressor was associated with a mixed hemodynamic profile, whereas the active stressor was associated with a clear myocardial profile. This study confirms that watching a video recording of oneself complete a speech task is associated with a more vascular response profile, a response associated with passive coping contexts.     

Influences on central hemodynamics in hemorrhage of beta 2-adrenergic vascular control mechanisms

Central hemodynamic responses evoked by standardized hemorrhage (exsanguination of 20 ml x kg bwt-1) were followed during 2 h in cats with intact and blocked vascular beta 2-adrenoceptors using the 'selective' beta 2-blocker, ICI 118, 551. In the first 10 min after bleeding blood pressure and cardiac output (CO) decreased and total peripheral resistance (TPR) increased by the same amount in the 'intact' and beta 2-blocked animals. Whereas blood pressure later on reached approximately the same hypotension level in both groups, other hemodynamic variables were distinctly different. In the 'intact' animals there was a gradual, partial recovery of stroke volume (SV) and CO in the face of a restoration to control of TPR. In the beta 2-blocked animals TPR continued to increase in the face of a maintained low CO and declining SV. The lower SV in the latter group was ascribed to abolition of beta 2-adrenergic restoration of plasma volume via absorption of tissue fluid into the circulation. The gradual decline of TPR in the 'intact' animals was attributed to beta 2-adrenergic dilator interaction with constrictor influences on the resistance vessels. It is concluded that beta-adrenergic vascular control mechanisms help to improve nutritional tissue blood flow during hemorrhage by increasing plasma volume, and hence venous return and CO, and by decreasing TPR. These reflex, beta 2-adrenergic circulatory events are similar to those aimed at in current shock therapy by transfusion and vasodilator treatment.     

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

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

Differential hostility profiles accompany different hemodynamic response patterns

Cardiovascular reactivity has been proposed as a mechanism by which psychosocial variables may lead lo coronary heart disease. Although reactivity as a generalized response has been linked lo psychological factors, there are specific hemodynamic profiles that underlie blood pressure reactivity. This study characterized subsets of young adults as myocardial or vascular reactors, in response to three laboratory tasks: mental arithmetic, videogame, and anger recall interview. Vascular reactors had higher diastolic blood pressure increases to all tasks, whereas reactor groups were equivalent at rest and on systolic blood pressure responses. Correlational analyses were conducted to determine whether psychological dimensions are uniquely associated with myocardial or vascular reactors' cardiovascular responses, at rest and during acute stressors. For myocardial reactors, resting systolic blood pressure was higher in hostile and suspicious individuals, whereas reactivity was linked to impulsivity. For vascular reactors, low trust, low gregariousness, and high depression were associated with diastolic reactivity to tasks. The predictive validity of hostility, distrust, sociability, and depression for cardiovascular pathology may vary with reactor type.     

Behavioral indices of threat and challenge in Hispanic adolescents and hemodynamic responses to a speech stressor.

Behavioral ratings of performance and nervousness during a speech were used to divide participants (n=54) into threat and challenge groups. Comparisons on cardiac output, Heather index, heart rate, vascular resistance, and blood pressure reactivity indicated greater myocardial responses for the challenge group. This study extends the threat-challenge literature by employing behavioral definitions of constructs and examining a Hispanic adolescent sample.     

Individual differences in adaptation of cardiovascular responses to stress

Previous research has described patterns of adaptation of cardiovascular responses across prolonged or recurring stress. However, despite important implications for the study of reactivity, relatively little research has directly examined the antecedents or consequences of this adaptation. We present data showing that neuroticism, a personality trait associated with dispositional appraisals of stress, is associated with reductions in HR, CO, and TPR responses across stress exposures. Comparisons of reactivity curves suggest blunted initial stress responses among persons with high neuroticism, and higher initial responses followed by greater decreases among persons with low neuroticism. The data also suggest an association between adaptation of cardiovascular responses and myocardial hemodynamic responding. Such findings shed new light on previous studies detecting healthful correlates of short-term stress responding, and highlight the relevance of adaptation to future cardiovascular reactivity research.     

Influences on central hemodynamics in hemorrhage of β2-adrenergic vascular control mechanisms

Central hemodynamic responses evoked by standardized hemorrhage (exsanguination of 20 ml×kg bwt^-1) were followed during 2 h in cats with intact and blocked vascular β₂-adrenoceptors using the ‘selective’β₂-blocker, ICI 118, 551. In the first 10 min after bleeding blood pressure and cardiac output (CO) decreased and total peripheral resistance (TPR) increased by the same amount in the ‘intact’ and β₂-blocked animals. Whereas blood pressure later on reached approximately the same hypotension level in both groups, other hemodynamic variables were distinctly different. In the ‘intact’ animals there was a gradual, partial recovery of stroke volume (SV) and CO in the face of a restoration to control of TPR. In the β₂-blocked animals TPR continued to increase in the face of a maintained low CO and declining SV. The lower SV in the latter group was ascribed to abolition of β₂-adrenergic restoration of plasma volume via absorption of tissue fluid into the circulation. The gradual decline of TPR in the ‘intact’ animals was attributed to β₂-adrenergic dilator interaction with constrictor influences on the resistance vessels. It is concluded that β-adrenergic vascular control mechanisms help to improve nutritional tissue blood flow during hemorrhage by increasing plasma volume, and hence venous return and CO, and by decreasing TPR. These reflex, β₂-adrenergic circulatory events are similar to those aimed at in current shock therapy by transfusion and vasodilator treatment.     

Shifting hemodynamics of blood pressure control during prolonged mental stress

The present study examined the hemodynamics underlying blood pressure elevations for evidence of a shift in the control of blood pressure during prolonged mental stress. Mean arterial pressure (MAP), cardiac output (CO), and total peripheral resistance (TPR) were measured at rest, during a 28-min mental arithmetic stress task, and during recovery, in 30 young healthy men and women. The stress task elicited a sustained increase in MAP: CO rose during the first half of the task but returned to baseline levels during the last quarter of the task, whereas TPR increased as the task progressed. When participants' hemodynamic reactions were classified as cardiac, vascular, or neither, there were more cardiac reactors early relative to late in the task, whereas there were more vascular reactors late relative to early. Thus, the sustained pressor response was initially supported mainly by cardiac mechanisms but subsequently by predominantly vascular mechanisms.     

Hydration status and cardiovascular function: effects of hydration enhancement on cardiovascular function at rest and during psychological stress.

This study examined the effects of a 3-day enhanced hydration regimen on resting cardiac function and reactivity to acute stress. Healthy volunteers (14 male, 14 female) were assigned to one of two groups: Enhanced Hydration and Normal Hydration Group. Participants in the Enhanced Group were given six 1-l bottles of water and instructed to drink two bottles a day in addition to normal fluid intake for 3 days preceding their laboratory session; no extra water was given to the Normal Group. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), cardiac output (CO), stroke volume (SV), and total peripheral resistance (TPR) were recorded during a 10-min baseline, 6-min Paced Auditory Serial Addition Test (PASAT), 5-min recovery, 5-min intermediate baseline, and 3-min Cold Pressor Test. Repeated-measures ANOVA revealed a significant Hydration GroupxTask interaction for DBP during the cold pressor (p<0.01) with the Enhanced Group exhibiting greater DBP reactivity to cold stress relative to the Normal Group. Analysis revealed significant Hydration GroupxGender interactions for SV and TPR (p<0.05) at rest and during both the PASAT and Cold Pressor Test. Females in the Enhanced Group displayed higher SV and lower TPR relative to Enhanced Group males, whereas females in the Normal Group displayed lower SV and greater TPR relative to Normal Group males. These results suggest that 3-day hydration enhancement influences blood pressure reactivity in both men and women, and that long-term hydration enhancement is related to resting gender differences in cardiac function.     

Influence of acute fluid loading on stress-induced hemoconcentration and cardiovascular reactivity

The goal of this study was to assess the possible attenuating effects of oral fluid loading on hematological and hemodynamic factors during acute psychological stress in two separate experiments: Experiment 1 assessed the effects of hypotonic fluid loading (water) and Experiment 2 assessed the effects of isotonic fluid loading (Gatorade). Twenty-eight participants were recruited for Experiment 1, and 28 participants were recruited for Experiment 2. Participants for each experiment completed two test sessions, once in a hypo-hydrated condition (following 12-h fast) and once in a fluid loaded condition (hypotonic or isotonic fluid). During each session, hematocrit (Hct), hemoglobin (Hgb), calculated plasma volume (CPV), heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), cardiac output (CO), stroke volume (SV), and total peripheral resistance (TPR) were assessed during a 10-min resting baseline period, 6-min mental arithmetic (MA) task, and a 16-min recovery period. Results for Experiment 1 revealed that the fluid load condition Hct, Hgb, and HR levels were significantly lower in comparison to the hypo-hydration condition, and that Hct, Hgb, and CPV reactivity was greater during the fluid load condition. Results for Experiment 2 revealed that Hct, Hgb, and TPR were lower and CPV, SBP, SV, and CO were higher during the fluid load condition compared to the hypo-hydration condition and that HR, CO, and TPR reactivity was greater during the fluid load condition. Finally, analytic comparisons between the two fluid types revealed that SV and CO levels were significantly greater at baseline and during MA when isotonic fluid was ingested compared to hypotonic fluid ingestion.     

Relationship quality moderates the effect of social support given by close friends on cardiovascular reactivity in women

We examined the role of the type of support provided, gender of support provider, and relationship quality in predicting how social support might influence cardiovascular reactivity during acute stress in women. A group of 88 women received either emotional, instrumental, or no support from a close female or male friend while performing a series of speech tasks. Results suggest that the effectiveness of social support for women depended primarily on the quality of the friendship (i.e., purely positive, or ambivalent). More specifically, women who interacted with a female, ambivalent friend had the largest changes in diastolic blood pressure, total peripheral resistance (TPR), and pre-ejection period compared to the other conditions. Furthermore, receiving emotional support from a purely positive friend was related to lower increases in cardiac output (CO) compared to a no-support condition. In contrast, receiving emotional support from an ambivalent friend was related to larger increases in CO and only small changes in TPR when compared to individuals in the no-support condition. These data are discussed in light of the psychosocial processes underlying social support effects in women, and the importance of a more comprehensive view of how close relationships influence cardiovascular function. This research was generously supported by Grant1 R01 MH58690-01 from the National Institute of Mental Health awarded to Bert N. Uchino.     

Cardiovascular reactivity and mental stress-induced myocardial ischemia in patients with coronary artery disease

This report evaluates the relationships of hemodynamic reactivity and determinants of myocardial oxygen demand to myocardial ischemia during mental stress in coronary artery disease patients. Thirty-nine patients and 12 controls were studied by radionuclide ventriculography during three mental tasks (arithmetic, Stroop task, and simulated public speaking). Patients were subdivided into three groups based on the severity of ischemic wall motion responses to the mental stressors. Results revealed that systolic blood pressure (SBP) levels during the mental tasks and SBP reactivity (increases) to stress were highest for the severely ischemic group, lowest for controls, with the mild-moderate ischemic and nonischemic patients in between. Severely ischemic patients started out with lower double product (heart rate x SBP) levels, and reached higher levels during the Stroop and speech tasks. There were no reliable group effects for diastolic blood pressure, heart rate, or left ventricular end-diastolic volumes. Among severely ischemic patients, the most potent task in eliciting ischemia (the speech) was associated with higher cardiovascular levels and elicited greater heart rate, double product, and ventricular volume responses. The present data indicate a relationship between cardiovascular levels and reactivity and the magnitude of ischemia induced by mental stress.     

Is blunted cardiovascular reactivity in depression mood-state dependent? A comparison of major depressive disorder remitted depression and healthy controls

Prior work has repeatedly demonstrated that people who have current major depression exhibit blunted cardiovascular reactivity to acute stressors (e.g., Salomon et al., 2009). A key question regards the psychobiological basis for these deficits, including whether such deficits are depressed mood-state dependent or whether these effects are trait-like and are observed outside of depression episodes in vulnerable individuals. To examine this issue, we assessed cardiovascular reactivity to a speech stressor task and a forehead cold pressor in 50 individuals with current major depressive disorder (MDD), 25 with remitted major depression (RMD), and 45 healthy controls. Heart rate (HR), blood pressure and impedance cardiography were assessed and analyses controlled for BMI and sex. Significant group effects were found for SBP, HR, and PEP for the speech preparation period and HR, CO, and PEP during the speech. For each of these parameters, only the MDD group exhibited attenuated reactivity as well as impaired SBP recovery. Reactivity and recovery in the RMD group more closely resembled the healthy controls. Speeches given by the MDD group were rated as less persuasive than the RMD or healthy controls' speeches. No significant differences were found for the cold pressor. Blunted cardiovascular reactivity and impaired recovery in current major depression may be mood-state dependent phenomena and may be more reflective of motivational deficits than deficits in the physiological integrity of the cardiovascular system.     

Sociotropic cognition moderates stress-induced cardiovascular responsiveness in women through effects on total peripheral resistance, but not cardiac output.

Although cardiovascular disease (CVD) remains the leading cause of mortality in women, few studies have examined the role of psychosocial factors in its development. This study examined the moderating effects of sociotropic cognition (SC), a need for social acceptance and approval, on psychosocial stress-induced cardiovascular responsiveness (CVR) and affect reactivity in women. Sixty-eight normotensive, college-aged females were randomly assigned to a low or high social threat condition. Measures of systolic, diastolic and mean arterial blood pressures (SBP, DBP and MAP, respectively), heart rate (HR), cardiac output (CO), total peripheral resistance (TPR) and negative affect were collected during rest, and under conditions of high vs. low interpersonal threat. A two-step hierarchical regression analysis was performed to predict all response variables (BPs, HR, CO, TPR and affect). Increases in SBP, DBP, MAP, TPR and negative affect were greater in the high threat than low threat condition. Changes in SBP, MAP and TPR positively covaried with SC under conditions of high interpersonal threat, but showed no significant covariation in the low threat condition. The data suggest that an excessive need for social acceptance may contribute to rises in BP through an increase in TPR, but not CO under conditions of high social threat.     

Hemodynamic profile of stress-induced anticipation and recovery.

Systolic and diastolic blood pressure, heart rate, stroke volume, cardiac output, and total peripheral resistance were measured in 100 healthy men and women with the aim of investigating hemodynamic profile during anticipation of, and recovery from, exposure to active and passive laboratory stressors. A 5-min anticipatory period preceded two tasks, both of which lasted 2.5 min. The tasks were mental arithmetic ('beta-adrenergic' stress) and the cold pressor test ('alpha-adrenergic' stress). Each task was followed by a 5-min recovery period. Blood pressure and heart rate were measured with a FinaPres 2300e, and stroke volume, cardiac output, and total peripheral resistance were computed from these parameters. Salivary cortisol was measured in relation to both tasks, and participants completed tests of state and trait anxiety, locus of control, and hostility. As expected, mental arithmetic and the cold pressor test elicited myocardial and vascular patterns of reactivity, respectively. However, contrary to expectations, anticipatory and recovery hemodynamic profile involved essentially vascular responding for both stressors. Salivary cortisol increased in response to both tasks but only weakly correlated with hemodynamic changes. None of the subjective measurements was a strong predictor of physiological reactivity. The findings suggest that stress-induced anticipatory and recovery reactivity may be generally vascular rather than myocardial. This could have important implications in light of suggestions that anticipatory and recovery responses may be better predictors of subsequent cardiovascular disease than direct stress-induced reactivity.     

Silent myocardial ischemia and cardiovascular responses to anger provocation in older adults

To determine if older, asymptomatic individuals with no prior history of coronary heart disease with exercise-induced silent myocardial ischemia (SI) during graded exercise treadmill testing exhibit exaggerated cardiovascular reactivity to anger provocation, we compared 42 SI participants and 95 controls. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) changes from baseline to three tasks & #x2014;anger recall, speech role-play, and mental arithmetic with harassment & #x2014;were assessed. Compared to controls, SI displayed greater HR responses for the speech role-play task only. The SI group was significantly older, had higher levels of fasting glucose and triglycerides, and had lower HDL-cholesterol. In multiple regression analyses, after controlling for these differences, SI was significantly associated with greater HR responses to the speech role-play. In sum, the SI group had significantly exaggerated HR responses to the speech role-play task, whereas SBP and DBP reactivity were comparable between groups. This suggests minimally enhanced cardiovascular reactivity among older SI patients that may nonetheless increase risk for cardiac events. This work was supported by National Institute on Aging (NIA) K24AG00930, NIA R29AG15112, aDepartment ofVeteran Affairs Geriatric Research, Education and Clinical Center Grant (GRECC), a VAMerit Grant, and the University of Maryland Claude D. Pepper Older Americans Independence Center (P60-AG12583). We thank Stephen Boyle for his assistance with data collection and development of the speech-role play task. We also thank Aron Siegman for his contributions to the initial conceptualization of this study. Correspondence concerning this article should be addressed to Shari R.Waldstein, Ph.D., Department of Psychology, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250.