Circulating levels of glucocorticoid hormones in WHHL and NZW rabbits: circadian cycle and response to repeated social encounter.

Social environment influences the progression of atherosclerosis in an important experimental model of disease, the Watanabe Heritable Hyperlipidemic rabbit (WHHL). Although the hypothalamic-pituitary-adrenocortical (HPA) system is likely to play an important role in the behavioral modulation of disease, relatively little is known about the glucocorticoid responses in these animals, or in other strains of rabbits. The purpose of the present study was to: (1) evaluate the rabbit glucocorticoid circadian rhythm, (2) compare plasma cortisol and corticosterone responses to social stress, and (3) examine strain differences (i.e., WHHL vs. New Zealand White (NZW)) in rabbit glucocorticoid responses to assess whether WHHLs have an aberrant HPA system. It was found that male rabbits secrete both corticosterone and cortisol in a circadian rhythm that peaks in the afternoon and reaches a nadir at 0600 h, i.e., approximately 12 h out-of-phase with the human glucocorticoid rhythm. Both glucocorticoids responded similarly to social stress induced by repeated daily 4 h pairings with another male rabbit; after 10 days of pairings, glucorticoid values were significantly correlated with the amount of defensive agonistic behavior exhibited. Finally, there were no significant strain differences in glucocorticoid circadian rhythms, baselines, or responses to social stress. These data suggest that glucocorticoid responses (i.e., circadian rhythms, responses to social stress) in the WHHL are similar to glucocorticoid responses in standard laboratory white rabbits.

Cardiovascular responsivity to stress in adolescents with and without persistently elevated blood pressure.

OBJECTIVES: The goal of this study was to compare the cardiovascular responses to behavioural stressors of three groups of adolescents who differed in blood pressure status across assessments. DESIGN: Casual blood pressure of adolescents who were identified as having elevated blood pressure during a school screen was re-evaluated in the laboratory. The adolescents were classified into two groups: (i) those with consistently elevated blood pressure across school and laboratory assessments and (i) those with labile blood pressure whose blood pressure in the laboratory was below 130/80 mmHg. A comparison group of adolescents with consistently normal blood pressure was also included. METHODS: Cardiovascular parameters were assessed during rest and during two behavioural stressors, the evaluated speaking task and the mirror tracing task. RESULTS: Adolescents with elevated blood pressure were more vascularly responsive across stressors than adolescents with labile blood pressure, who, in turn, were more reactive than adolescents with normal blood pressure. CONCLUSIONS: These results suggest that vascular reactivity to behavioural stressors may be useful in predicting risk of hypertension because of its sensitivity in distinguishing adolescents with consistently elevated blood pressure from those with labile blood pressure and those with normal blood pressure.

Health psychology: psychosocial and biobehavioral aspects of chronic disease management.

Psychosocial factors appear to impact upon the development and progression of such chronic diseases as coronary heart disease, cancer, and HIV/AIDS. Similarly, psychosocial interventions have been shown to improve the quality of life of patients with established disease and seem to influence biological processes thought to ameliorate disease progression. Small-scale studies are useful for specifying the conditions under which psychosocial factors may or may not impact quality of life, biological factors, and disease progression. They are also useful for informing us about the conditions under which psychosocial interventions can serve as adjuvants (e.g. adherence training) to medical treatments. Only large-scale clinical trials, however, can determine the extent to which these psychosocial interventions may impact morbidity and mortality.

Piecewise latent growth curve modeling of systolic blood pressure reactivity and recovery from the cold pressor test.

Latent growth curve methodology was used to model systolic blood pressure reactivity and recovery from the cold pressor test. A piecewise regression approach permitted the separate but simultaneous modeling of the two components (reactivity and recovery) of the stress process. Data came from a study of 99 participants classified on the basis of gender, ethnicity, and family history of hypertension. Their systolic blood pressure was assessed at rest, during the cold pressor test, and during a task recovery period. A measure of task appraisal and readings from ambulatory blood pressure monitoring during a workday were also examined. The article illustrates a step-by-step approach to modeling reactivity and recovery. Results indicated that both reactivity and recovery were associated with subsequent systolic blood pressure at work.

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 y-intercept from the linear regression of the CO reactivity 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 homogenous groups of participants based on the relative extent to which myocardial or vascular mechanisms dominate the reactivity to stress.

Cardiovascular and perceptual effects of reporting pain during the foot and forehead cold pressor tests.

In research involving the cold pressor test, a tacit presumption is often made that reporting pain during stimulation is not in itself reactive. This study examined whether, for the foot and forehead cold pressor tests, activities involved in reporting pain may affect (a) the evoked pattern of cardiovascular response, and (b) the magnitude of self-perceived pain. In 40 normotensive college men, increases in systolic blood pressure were greater during test sessions that included verbal ratings of pain, as compared to sessions in which pain was not reported. In contrast to its effect on physiological activation, reporting pain did not significantly alter the participant's perception of the painfulness of the lest, on recollection shortly after the test. We conclude, therefore, that reporting pain during the cold pressor test may impose significant additional demands on the cardiovascular system, but it does not interfere significantly with the processing of nociceptive information.

Influence of ethnicity and gender on cardiovascular responses to active coping and inhibitory-passive coping challenges.

OBJECTIVE: The goal of this study was to evaluate how black and white men and women responded physiologically to specific laboratory challenges. METHODS: Hemodynamic responses to an active coping (evaluated speaking) and two inhibitory-passive coping (mirror tracing, cold pressor) tasks were examined in 138 black and white men and women. RESULTS: Significant ethnicity by gender interactions occurred for the evaluated speaking task. Black men responded with lower blood pressure, cardiac output or heart rate, or both, than black women, white men, and white women, who did not differ from each other. Black men, relative to the other subgroups, also reported more inhibitory-passive coping, hostility, and pessimism, and less social support. Whites also responded with greater increases in systolic blood pressure during mirror tracing than blacks. CONCLUSIONS: These findings indicate that black-white differences in physiological responsivity obtained for men may have limited generalizability for women. The results also suggest that environmental and social factors rather than genetic or constitutional factors may play a role in black-white reactivity differences.

Stimulus dimensions of the cold pressor test and the associated patterns of cardiovascular response.

Hemodynamics of the cold pressor response in relation to its pain and nonpain stimulus components were investigated in normotensive college men using the foot and forehead cold pressor tasks. Mechanisms of pain- and non-pain-related increases in blood pressure were analyzed as residual effects of concurrent changes in total peripheral resistance and cardiac output. The identified partial relationships suggested that the response pattern associated with pain included positive change both in cardiac output and in total peripheral resistance, whereas the nonpain-related response was limited to an increase in total peripheral resistance. Analyses of individual differences in cardiovascular responses to pain further indicated that pain-related increments in blood pressure were mediated by a steeper rise in total peripheral resistance, an increase in heart rate, and an apparent increase in preload. At baseline, high reactors to pain manifested relatively elevated total peripheral resistance, diminished cardiac output, and an indication of a reduced inotropic state, suggesting that altered basal homeostasis may discriminate normotensive individuals displaying heightened cardiovascular reactivity to aversive cold stimulation.

Differential patterns of dynamic cardiovascular regulation as a function of task.

In cardiovascular reactivity studies, interpretations of the processes supporting the blood pressure response may become problematic when systolic blood pressure, diastolic blood pressure, and heart rate all increase in response to a behavioral challenge. Therefore, in addition to evaluating these cardiovascular responses, this study examined cardiac output, total peripheral resistance and systolic time intervals derived from impedance cardiogram, electrocardiogram and phonocardiogram recordings during a speech stressor, a mirror tracing task, and a foot cold pressor test. All of the behavioral stressors elicited increases in blood pressure and heart rate, with the largest changes occurring during the overt speech. Based on the examination of the response patterns of the underlying hemodynamic variables it would appear that, in both men and women, the blood pressure increase during the speech preparation period was supported by increased cardiac output; the speech itself resulted in a mixed pattern of increased cardiac output and total peripheral resistance; whereas, the mirror tracing and cold pressor tasks produced increased total peripheral resistance. Although men and women produced similar response patterns to the behavioral challenges, sex differences in the estimates of myocardial contractility were observed during rest. These results provide evidence that different behavioral stressors can produce a distinct yet integrated pattern of responses, whose differences may be revealed, when impedance cardiography is used, to derive sufficient response measures for assessing dynamic cardiovascular processes.

The cold pressor test: vascular and myocardial response patterns and their stability.

The purposes of the present study were to compare the cardiovascular response patterns evoked by three versions of the cold pressor test (either forehead stimulation or hand or foot immersion) and to determine the reproducibility of the responses over a 2-week interval. Blood pressure, heart rate, stroke volume, cardiac output, total peripheral resistance, and systolic time intervals were obtained during rest and during the cold pressor test in 42 young men. Across conditions, the pressor response was supported by peripheral resistance increases with concomitant stroke volume decreases. Although the response patterns were generally similar across sites, exceptions were apparent for heart rate. Forehead stimulation was characterized by no significant change in heart rate, whereas limb (hand or foot) immersion was associated with significant heart rate acceleration. The responses elicited by the three cold pressor test conditions were reliable and showed little evidence of attenuation over the test-retest interval.

The stability of cardiovascular parameters under different behavioral challenges: one-year follow-up.

The stability of myocardial, peripheral vascular and systolic time-interval measures was assessed over a one-year period in a sample of ten healthy normotensive men. Subjects participated in three laboratory sessions, the first two of which were two weeks apart, and the third approximately one year later. Measures were sampled during the preparation and delivery of a speech, a mirror star tracing task, and the forehead cold pressor test. The results of intraclass correlations computed between the mean of the first two sessions and the third showed that baseline and task levels were highly reproducible across all tasks and most parameters over the one year interval. Results also showed that the long term stability of delta is largely task-dependent.

Patterns and stability of cardiovascular responses to variations of the cold pressor test.

Test-retest reliabilities and patterns of heart rate and blood pressure responses were examined using variations in the cold pressor test in 113 normotensive white college men. Comparisons were made of stimulus site (forehead vs. foot) and bodily posture (seated vs. supine) across four separate groups of men. The stability of cardiovascular responses was examined over a 2-week-test-retest interval. Different cardiovascular response patterns emerged as a function of stimulation site and posture. Systolic and diastolic blood pressure increases were accompanied by bradycardia in the forehead cold pressor task but by tachycardia in the foot cold pressor task. Systolic blood pressure increases were larger for foot than for forehead stimulation. Heart rate increases were larger for supine than for seated men. Effects on response were independent of postural differences at baseline, and there were no stimulation site by posture interactions. The cardiovascular responses to stimulation did not attenuate across sessions in any experimental condition but were more reliable for foot than for forehead stimulation and for supine than for seated posture. Short-term stability for changes to the task approached that for baseline and task and was higher than has been reported elsewhere.

Myocardial and peripheral vascular responses to behavioral challenges and their stability in black and white Americans.

The purpose of this study was to assess the short term stability of myocardial and peripheral vascular responses to behavioral challenges, and to compare the response patterns of Black and White men. Blood pressure and heart rate, as well as stroke volume, cardiac output, total peripheral resistance, and systolic time interval measures derived from the impedance cardiogram were obtained in 12 Black and 12 White men. These measures were taken prior to and during an evaluative speech stressor, a mirror star tracing task, and a forehead cold pressor test presented during two laboratory sessions scheduled two weeks apart. In general, total peripheral resistance and impedance-derived baseline measures showed acceptable reproducibility (G greater than .85). With a few exceptions, adequate reliability was also demonstrated for change (delta) scores. All tasks raised blood pressure responses above resting levels. Blacks demonstrated significantly greater increases in total peripheral resistance responses across tasks. Whites but not Blacks also revealed increases above baseline in cardiac output and contractility as estimated by the Heather Index. These findings are consistent with the view that Blacks show greater vascular responsiveness than Whites across a variety of tasks, but reveal less myocardial responsiveness.

Influence of age, sex, and family on Type A and hostile attitudes and behaviors.

We describe the influence of age, sex, and family on Type A and hostility indices that have been related to rates of coronary heart disease (CHD). The sample consisted of 120 girls and 95 boys (ages 6 to 18 years) and 141 women and 120 men (ages 31 to 62 years) from 142 families residing in an upper middle class community. Results showed little familial aggregation of Type A and hostility. Adults had higher Structured Interview (SI) Potential for Hostility ratings than did children, whereas children had higher Minnesota Multiphasic Personality Inventory (MMPI)-derived Hostility scores and SI Anger-In ratings than did adults. Male adults and male children had higher SI Potential for Hostility ratings and MMPI-derived Hostility scores than did their female counterparts. The heightened hostility of males may account, in part, for their heightened risk of CHD relative to females'.

The reliability and specificity of delta versus residualized change as measures of cardiovascular reactivity to behavioral challenges.

The statistical parameters that influence the reliability of delta and residualized change were examined in the context of the assessment of cardiovascular reactivity. A comparison of the relative reliabilities of these two quantification methods was performed using systolic blood pressure, diastolic blood pressure, and heart rate data from two samples of 134 and 109 subjects observed during baseline and either two or four behavioral challenges. The results indicated that both delta and residualized change scores can yield reliable measures of blood pressure and heart rate reactivity to behavioral challenges, and that their reliabilities will be comparable under the conditions observed in laboratory reactivity studies. Correlations between baseline and delta did not indicate that these two measures were systematically related. Finally, delta scores are more appropriate than residuals when assessing the generalizability of responses across a variety of tasks.

Blood pressure reactivity and perception of pain during the forehead cold pressor test.

The relationship between blood pressure reactivity and the perception of pain was examined during a series of three forehead cold pressor tests given every other day to a group of 18 male college students. Subjects classified as high reactors on the basis of peak increases in mean blood pressure during cold pressor tests perceived the cold pressor stimulus as more painful than subjects classified as low reactors. The propensity to rate the cold pressor stimulus as painful was positively correlated with the individual level of blood pressure reactivity (baseline-free partial r = .62). Intra-individual correlations between pain and blood pressure responses were unrelated to subjects' reactivity status. Across the 3-min test, correlations between pain and blood pressure reactivity (with the effects of baseline blood pressure levels partialled out) were significant only during periods when levels of responses were relatively high. The heart rate responses were unrelated to pain ratings. Generalizability theory was applied to the analysis of temporal stability of cold pressor reactions. Both blood pressure and pain responses were highly reproducible across three sessions, appearing to express stable individual differences. The efficacy of 800 mg oral ibuprofen in controlling the cold pressor pain was also tested. Analgesic activity of the drug during the cold pressor test could not be demonstrated.

Race and blood pressure status influences cardiovascular responses to challenge.

The influence of race and blood pressure status on cardiovascular responses to three challenges (interview, video game and cold pressor) was investigated in 50 healthy normotensive and 30 unmedicated mild-to-moderate hypertensive black and white men, aged 25-44 years old. Group differences were obtained for two tasks. The interview evoked race and blood pressure status differences: higher heart rate responses were elicited from normotensives compared with hypertensives and larger diastolic blood pressure (DBP) responses were elicited from whites compared with blacks. For the video game, black hypertensives displayed larger DBP responses than white hypertensives and greater systolic blood pressure and DBP responses than black normotensives. The video game heart rate response of white normotensives exceeded that of black normotensives and white hypertensives. These findings suggest that cardiovascular responses to challenge are affected by race and blood pressure status. The blood pressure hyperresponsiveness of black hypertensives compared with black normotensives to a psychological challenge (video game) provides generality to previous research conducted only on whites.

Effects of parent presence on children's reactions to injections: behavioral, physiological, and subjective aspects.

Observed 47 children ranging in age from 13 months to 7 years 9 months receiving injections as part of a regular visit to a pediatric clinic. Twenty-three children were randomly assigned to a condition with parent (mainly mothers) present and 24 to a condition with parent absent. During the medical procedure, the child's reactions were observed via videotape (for later behavioral coding) and physiological recording (to measure heart rates). Following the injection, data were collected on the child's preference of condition (either parent present or parent absent) for future injections. Older children (but not younger ones) showed significantly more behavioral distress when the parent was present. However, the oldest children's preference of condition for future injections was overwhelmingly that of parent present (86%).

Premenopausal and postmenopausal women differ in their cardiovascular and neuroendocrine responses to behavioral stressors.

Middle-aged (45-51 years) women performed four tasks while their heart rate, blood pressure, and plasma catecholamines were measured. The tasks were serial subtraction, mirror image tracing, speech, and postural tilt. The speech task was considered to be particularly relevant to women because of its emphasis on social skills. Fifteen premenopausal women reported menstruating regularly and were tested in the early follicular phase. Sixteen postmenopausal women reported not menstruating for at least 12 months and their hormonal status was verified by serum levels of follicle-stimulating hormone. Results showed that postmenopausal women exhibited greater increases from baseline in heart rate during all tasks, relative to premenopausal women, with a particularly pronounced increase during the speech task. Postmenopausal women exhibited greater increases from baseline in systolic blood pressure and epinephrine, relative to premenopausal women, during the speech task only. Explanations for the stressor-specific effect of menopausal status were discussed. The results suggest that reproductive hormones may interact with stressor characteristics to determine middle-aged women's physiological responses to stress.

Associations of blood pressure with self-report measures of anger and hostility among black and white men and women.

This study examined associations between blood pressure (BP) and dispositional variables pertaining to anger and hostility. Black and White 25- to 44-year old male and female normotensives and unmedicated mild to moderate hypertensives completed four reliable self-report scales--the Cook-Medley Hostility (Ho) Scale, the Trait Anger subscale of the State-Trait Anger Scale (STAS-T), and the Cognitive Anger and Somatic Anger subscales of the Cognitive-Somatic Anger Scale--plus the Framingham Anger Scale and the Harburg Anger Scale. They also engaged in three laboratory tasks--Type A Structured Interview (SI), a video game, and a cold pressor task--that elicit cardiovascular reactivity. Ambulatory BP readings at home and at work were also obtained from most subjects. Blacks had significantly higher Ho and lower STAS-T scores than did Whites. Women reported higher levels of somatic anger than did men. White women showed significant positive correlations between STAS-T and systolic BP (SBP) and diastolic BP (DBP) both at rest in the laboratory and during the SI. Black women revealed significant positive relationships between STAS-T and SBP and DBP at rest in the laboratory and at work as well as with DBP during the cold pressor test. For Black men, cognitive anger and DBP at rest were positively related. In contrast, White men revealed significant negative correlations between Ho scores and SBP at rest and during the video game; these men also showed significant negative relationships between somatic anger and SBP and DBP reactivity during the cold pressor test. Women, but not men, showed significant positive relationships between all four anger measures and ambulatory BP at work. Whereas main effects relating anger and cardiovascular measures were not apparent as a function of race, Blacks demonstrated significantly greater SBP and DBP reactivity than Whites during the cold pressor test, with the converse occurring during the SI. Men demonstrated significantly greater DBP reactivity than women during the video game. The present findings indicate that self-reports on anger/hostility measures and cardiovascular responses to behavioral tasks differ as a function of race but that relationships between anger and BP regulation need to take into account possible race-sex interactions and selection of anger/hostility measures.