Heart Rate Reactivity, Behavior Pattern, and Parental Hypertension as Predictors of Cardiovascular Activity During Cognitive Challenge

Hemodynamic responses were studied during work on serial subtraction and digits backwards tasks in 99 healthy male undergraduates jointly classified as high or low heart rate reactors, Type A or Type B behavior pattern, and as having positive or negative parental history of hypertension. Heart rate, systolic blood pressure, and diastolic blood pressure were recorded, and rate pressure product was calculated at rest and during the tasks. High heart rate reactors to a cold pressor task responded with relatively higher heart rate and rate pressure product during both cognitive tasks than low heart rate reactors. Type A subjects defined by Jenkins Activity Survey did not differ from Type Bs on any of these physiological variables, although behavioral evidence demonstrated greater effort and superior performance by the Type As. Subjects with a positive parental history of hypertension manifested greater systolic and diastolic pressures and rate pressure product responses to the cognitive challenge than those lacking such parental history. These results indicate that the individual difference variables of heart rate reactivity and parental history of hypertension predicted different hemodynamic response patterns to behavioral challenge.     

What do Arithmetic Stress Tests Measure? Protocol Variations and Cardiovascular Responses

Three studies tested the effects of the following design/protocol variations in mental arithmetic: 1) Order of task, 2) vocal versus written delivery of responses, 3) effects of different types of superimposed noise distractors, and 4) varying types of mental arithmetic challenges. All studies used the same basic protocol with 20-min adaptation, 5-min task, and 3-min recovery periods; dependent cardiovascular variables were systolic and diastolic blood pressure and heart rate; in Study 2 respiration rate and respiratory amplitude were also assessed. Findings showed that vocal delivery enhanced subjective distress, lowered performance, and enhanced diastolic blood pressure responses. Noise distraction augmented distress but did not affect task performance. Variable noise distraction augmented systolic blood pressure and heart rate responses but only when math equations were presented on a video screen. Autonomic response adaptation was apparent from first to second tasks but not thereafter. The built-in replications strengthened these findings.     

The stability of cardiovascular reactivity: Effects of task-type and family history over a 3-year interval

Although there are now more than one-half dozen published studies examining the longitudinal stability of cardiovascular reactivity, methodological limitations leave several important issues unexplored. In this investigation, 126 disease-free participants completed a laboratory protocol containing physical (hand-grip), cognitive (mental arithmetic), and speech (anger recall interview) tasks at the beginning and end of a 3-year interval. In addition, we collected information regarding family history of hypertension. As expected, blood pressure and heart rate reactivity was statistically reproducible across the 3-year time interval, but coefficients were moderate at best (rs =.37 diastolic blood pressure [DBP], .25 systolic blood pressure [SBP], & .22 heart rate [HR]). In addition, participants with a positive family history of hypertension showed greater stability of systolic reactivity. We conclude that (a) the long-term reproducibility of reactivity is strongly affected by the number of measurements, and (b) family history and task-type may have modest effectson the reproducibility ofcardiovascular reactivity.     

Cardiovascular Responses to Mental Arithmetic and Handgrip During Different Conditions of Postural Change

Twenty healthy male subjects, aged 18–29 yrs, were studied during three sequences of four different postural trials-sitting, sitting to standing, standing, and standing to sitting. The first sequence was a baseline, without other stimulation. In the remaining two, subjects performed a mental arithmetic task and an isometric handgrip task during each trial (counterbalanced). Systolic blood pressure, diastolic blood pressure, heart rate, and skin conductance were recorded during the trials. The physiological responses to the two tasks were shown to vary as a function of the specific postural trial. Systolic and diastolic blood pressure were generally more sensitive to these effects than heart rate or skin conductance. The two tasks facilitated increases in blood pressure during the sitting to standing trials, especially during the standing phase. The increases in blood pressure were comparable to those reported previously for voluntary control and biofeedback procedures. Mental and physical strategies are effective in increasing blood pressure during postural change and may be useful in the management of orthostatic hypotension.     

Family history of hypertension,gender, and cardiovascular reactivity and stereotypy during stress

Thirty subjects with a family history of hypertension and 28 subjects without such a history performed a Stroop Color-Word Interference task, a mental arithmetic task (serial subtraction of sevens), and a shock avoidance task (repeating digits backward while expecting to be shocked for mistakes). Systolic and diastolic blood pressure and pulse rate were recorded while subjects anticipated, undertook, and recovered from the shock avoidance task and undertook and recovered from the Stroop and mental arithmetic tasks. It was found that compared to nonfamily history subjects, family history subjects manifested reliably greater cardiovascular reactivity during each task and in anticipation of the shock avoidance task. These results are congruent with the notion that excessive sympathetic nervous system reactivity—possibly genetically determined—is involved in the development of some form(s) of essential hypertension. Further, the results indicated that family history subjects manifested greater consistency, or stereotypy, of cardiovascular response across the experimental tasks than nonfamily history subjects. The possible role of cardiovascular stereotypy in the development of essential hypertension is also discussed.This investigation was supported by University of Kansas General Research Allocation 3115-xO-0038 to B. Kent Houston.     

Physiologic responses to cognitive challenge during pregnancy: effects of task and repeat testing.

Physiological responses to stress during pregnancy are believed to influence birth outcomes. Researchers have studied pregnant women in laboratory stressor paradigms to investigate these associations, yet normative data on cardiovascular and respiratory responses to laboratory challenge during pregnancy are not yet established. To begin to establish such normative data, this study examined the effects of task and repeat stressor exposure on reactivity in third-trimester pregnant women. Thirty-one healthy pregnant women (mean age=27 years; range 18-36) between the 33rd and 39th week of pregnancy, were instrumented for continuous electrocardiography, blood pressure (BP), and respiration data. Subjects rested quietly for a 5-min baseline and then performed both a mental arithmetic stressor and a Stroop color-word-matching task, each 5 min in length and each followed by a 5-min recovery period. The order of the tasks was counterbalanced. After each 5-min period, subjects rated the period on a 10-point stress scale. Averaged across task type and challenge period, systolic and diastolic BP and respiration rate increased significantly in response to cognitive challenge, but heart rate (HR) did not. When data were examined for task and period effects, the following results emerged: the Stroop task elicited significantly greater systolic BP and HR reactivity than the arithmetic task, yet subjects rated the arithmetic task as more stressful. Averaged across task type, subjects showed greater systolic BP reactivity during the second challenge period compared to the first. Finally, women's BP tended to drift upward and did not return to baseline during the first recovery period. These findings indicate that averaging data across tasks and periods can obscure the time course of response patterns that may be important in the study of associations between maternal stress and perinatal development, as well as in other research on reactivity to repeat stress exposure.     

Cardiovascular Responses of Adolescents During a Naturally Occurring Stressor and Their Behavioral and Psychophysiological Predictors

The present investigation examined the behavioral and psychophysiological characteristics of 23 adolescents who differed in levels of blood pressure and heart rate prior to and following a naturally occurring stressor–giving a required five-minute speech in a high school English class. Measured characteristics were Type A behavior, hostility and anger, trait anxiety, family history of hypertension, and blood pressure and heart rate responses to three standardized laboratory stressors (serial subtraction, star-tracing, and handgrip tasks). Results showed that anxious adolescents achieved elevated levels of systolic blood pressure and heart rate during public speaking relative to the next English class, whereas angry adolescents achieved elevated levels of diastolic blood pressure. Those adolescents who exhibited exaggerated increases in the cardiovascular measures while performing laboratory tasks also achieved elevated levels of blood pressure and/or heart rate during the naturally occurring stressor, but the strength of the relationships varied across tasks and physiological parameters. These findings should be viewed as tentative because of the uniqueness and size of the sample.     

Cardiovascular reactivity assessment: effects of choice of difficulty on laboratory task responses.

This laboratory study of cardiovascular reactivity was designed to examine how a choice of difficulty element in a mental arithmetic task would affect cardiovascular responses. 20 healthy male subjects were tested on a computer-controlled mental arithmetic task, designed to standardize performance across subjects by keeping constant the proportion of correct responses. This was achieved by automatic adjustment of problem difficulty according to ongoing performance. Subjects were led to believe that they could take either a 'difficult' or an 'easy' version of the mental arithmetic task and were asked to make a choice; in fact, all subjects were given the same task. Subjects who chose the 'difficult' mental arithmetic task (N = 10) showed significantly greater increases in myocardial contractility, cardiac output and systolic blood pressure during task performance than those who chose 'easy' (N = 10). However, subjects who chose 'difficult' were presented with more difficult problems presumably due to their exerting greater levels of effort during the task. The differences in cardiovascular responses associated with choice of difficulty were absent during testing on four subsequent tasks which did not incorporate any choice options (reaction-time, speech, mirror trace, cold pressor). These findings are interpreted as being provocative, rather than in any way conclusive. Nevertheless, they are suggestive of the possibility that choice of difficulty in laboratory tasks may be one strategy for improving the ecological validity of laboratory reactivity assessment procedures.     

Effects of menstrual phase and parental history of hypertension on cardiovascular response to cognitive challenge

The effects of parental history of hypertension and menstrual phase on systolic and diastolic blood pressure (SBP, DBP) and heart rate (HR) responses to two frustrating cognitive tasks were examined in 47 normotensive, young adult women. Subjects with and without a parental history of hypertension were scheduled to be tested during either the follicular (days 7-11 of a 28-day cycle) or luteal (days 17-22) phase of the menstrual cycle. During the laboratory session, HR, SBP, DBP, and self-report of affective states were measured while subjects performed two cognitive tasks (mental arithmetic and concept formation). Results indicated that the magnitude of SBP responses to the two tasks was significantly greater in subjects tested during the follicular phase than in subjects tested in the luteal phase of the menstrual cycle. No effect of parental hypertension was observed on cardiovascular response measures, though offspring of hypertensive parents reported experiencing significantly less anger during the tasks than subjects with normotensive parents.     

Psychophysiological Reactivity in Cardiac Transplant Recipients

To assess the contribution of the heart's autonomic innervation to reactivity to psychological stressors, hemodynamic responsiveness of the denervated human heart was examined in two studies. In Study 1, cardiac output measured by thermodilution. heart rate, and systolic and diastolic blood pressure responses to a 4-min mental arithmetic task were studied in 7 cardiac transplant patients during routine post-transplant cardiac catheterization. In Study II, 6 cardiac transplant patients, 5 normal controls, and 5 renal transplant patients participated in a 78-min psychophysiological stress protocol during which heart rate, systolic and diastolic pressure, and cardiac output (measured noninvasively by impedance cardiography) as well as serum epinephrine and norepinephrine were measured at baseline and while subjects performed mental arithmetic and reaction time tasks. In Study I, transplant patients showed significant increases, relative to baseline, in heart rate, systolic blood pressure, and cardiac output in response to mental arithmetic. The diastolic blood pressure response was marginally significant. In Study II, mental arithmetic produced significant reactivity in systolic blood pressure and marginally significant increases in heart rate and diastolic blood pressure in cardiac transplant patients. Reaction time produced only marginally significant diastolic blood pressure reactivity. Hemodynamic reactivity of the cardiac transplant group generally was lower than that of the two innervated groups, which generally were similar to each other. Although the small number of subjects makes conclusions tentative, these data suggest that: 1) Cardiac transplant patients are capable of significant reactivity to psychological stressors despite the absence of innervation of the heart, and 2) reactivity to these stressors is diminished relative to innervated control subjects. In the absence of cardiac innervation, reactivity is due to the vascular system and cardiac effects mediated by humoral factors.     

Cardiovascular reactivity and family history of hypertension: a meta-analysis

A regression-based meta-analysis examined the degree to which the effects of a family history of hypertension on cardiovascular reactivity are moderated by the magnitude of cardiovascular responses elicited in challenge/task conditions. Mean change scores for negative family history groups were regressed on mean change scores for positive family history groups. The slopes of separate regression lines obtained for systolic and diastolic blood pressure and heart rate were significantly less than 1.0 and the y-intercepts for these regression lines were significantly greater than zero. This pattern indicates that family history differences in cardiovascular reactivity to stress are greatest in situations that elicit the smallest baseline-stressor change scores in non-family-history groups.     

The role of affect and rumination in cardiovascular recovery from stress

This study examined the psychological processes that may impede or facilitate cardiovascular recovery. It was hypothesized that cardiovascular recovery would be hampered by negative affect and rumination, and facilitated by positive affect. In an experimental study, stress was elicited by exposing participants (N = 110) to a mental arithmetic task with harassment. After the stress task, affective levels were manipulated via a movie scene with negative, neutral, or positive emotional valence, or without an affect manipulation (control condition). During the entire experiment, heart rate and systolic and diastolic blood pressure levels were measured continuously. Results indicated that blood pressure recovery was hampered by the negative affect manipulation and by rumination. However, the positive affect manipulation did not facilitate blood pressure recovery. No effects were found on heart rate recovery. In sum, the findings emphasize the importance of negative affect and rumination in stress recovery.     

Stability of individual differences in cellular immune responses to two different laboratory tasks

To explore the stability of immune reactivity across laboratory tasks, we correlated enumerative and functional lymphocyte responses to a speech task and a mental arithmetic task, delivered on the same occasion of testing in 31 healthy undergraduates. Both tasks were associated with an increase in peripheral CD8+ and CD56+ cell populations, and a decrease in proliferative response to phytohemagglutinin (PHA) and ratio of CD4:CD8 cells. Intertask correlations were significant for the magnitude of change in proliferative responses at two different concentrations of PHA, r = 0.76, p < .0001 and r = 0.46, p < .05, and in numbers of circulating CD56+ cells, r = 0.46, p < .005. Concomitant heart rate and systolic blood pressure responses also correlated significantly over the two experimental tasks (heart rate: r = 0.52 and systolic blood pressure: r = 0.58. ps < .0005). These data provide initial evidence that interindividual variability of some cellular immune responses is moderately reproducible across different stimulus conditions, providing further evidence that it may denote a stable individual difference.     

Family history of cardiovascular disease is associated with cardiovascular responses to stress in healthy young men and women.

Heightened cardiovascular stress responsivity is associated with cardiovascular disease, but the origins of heightened responsivity are unclear. The present study investigated whether disturbances in cardiovascular responsivity were evident in individuals with a family history of cardiovascular disease risk. Data were collected from 60 women and 31 men with an average age of 21.4 years. Family history of cardiovascular disease risk was defined by the presence of coronary heart disease, hypertension, diabetes or high cholesterol in participants' parents and grandparents; 75 participants had positive, and 16 had negative family histories. Systolic and diastolic blood pressure (BP), heart rate and heart rate variability were measured continuously for 5 min periods at baseline, during two mental stress tasks (Stroop and speech task) and at 10-15 min, 25-30 min and 40-45 min post-stress. Individuals with a positive family history exhibited significantly greater diastolic BP reactivity and poorer systolic and diastolic BP recovery from the stressors in comparison with family history negative individuals. In addition, female participants with a positive family history had heightened heart rate and heart rate variability reactivity to stressors. These effects were independent of baseline cardiovascular activity, body mass index, waist to hip ratio and smoking status. Family history of hypertension alone was not associated with stress responsivity. The findings indicate that a family history of cardiovascular disease risk influences stress responsivity which may in turn contribute to risk of future cardiovascular disorders.     

Secretory immunoglobulin A and cardiovascular activity during mental arithmetic and paced breathing.

The role of the autonomic nervous system in secretory immunoglobulin A (sIgA) responses to laboratory challenge was explored in a study in which sIgA and cardiovascular activity were recorded at rest and during mental arithmetic and paced breathing. These tasks were selected to preferentially engage the sympathetic and parasympathetic nervous systems, respectively. Mental arithmetic elicited a mixed pattern of increased alpha- and beta-adrenergic activity and a reduction in parasympathetic activity; diastolic blood pressure, total peripheral resistance, and systolic blood pressure increased, preejection period shortened, and heart rate variability decreased. In contrast, paced breathing primarily elicited an increase in parasympathetic activity; heart rate variability increased. Mental arithmetic also provoked an increase in sIgA concentration but no change in saliva volume, whereas paced breathing affected neither sIgA concentration nor saliva volume. These data suggest that sIgA responses to laboratory challenges are mediated by sympathetic rather than parasympathetic processes.     

Cardiovascular Effects of Mental Arithmetic in Type A and Type B Females

The cardiovascular responsivity of women demonstrating the Type A coronary-prone behavior pattern was investigated by presenting female Type A and Type B subjects with a challenging mental arithmetic task. Female subjects responded to the task with elevations in heart rate, blood pressure, and forearm blood flow, but did not show the active vasodilatation in the forearm vasculature seen in males in an earlier study. Type A females as a group were not hyperresponsive compared to Type B. However, measures of Type A behavior interacted with family history of hypertension such that, in the subgroup with a positive family history, the Type A behavior pattern was associated with larger cardiovascular responses. The results suggest that sex differences could be present in the expression of the cardiovascular concomitants of Type A behavior. Both gender and family history of cardiovascular disease may represent additional dimensions in the understanding of the pathological mechanisms linking Type A behavior and coronary disease.     

Parental History of Essential Hypertension, Active Coping, and Cardiovascular Reactivity

Differences in cardiovascular reactivity to stress between individuals with and without a family history of essential hypertension (EH) may be affected by stimulus characteristics and/or individual differences in behavioral response. Twenty-four male students with a parental history of EH and 24 without a parental history of EH participated in two laboratory sessions during which two “active’ (mental arithmetic and the Stroop word-color interference test) stressors and one “non-active’ (isometric hand-grip) stressor were presented. Family history subjects exhibited greater systolic blood pressure responses than non-family history subjects only to the two active stressors in Session 2, despite the fact that, overall, isometric hand-grip elicited the largest responses. High-performing Stroop subjects with a parental history of EH displayed greater heart rate responses to the task than high-performing subjects without a parental history of EH in both sessions. No group differences appeared among poor performers. The degree to which a stressor encourages active coping behavior appears to be one determinant of differences in cardiovascular response between individuals with and without a family history of EH.     

Cardiovascular and Metabolic Activity at Rest and During Psychological and Physical Challenge in Normotensives and Subjects With Mildly Elevated Blood Pressure

Heart rate, systolic and diastolic blood pressure, and respiratory and metabolic activity were recorded prior to and during mental arithmetic and a video game task in 20 young men with mildly elevated casual systolic blood pressures. Twenty-five unambiguously normotensive young men were tested under the same protocol. For pretask baseline physiological activity, group differences emerged for all cardiovascular and metabolic variables; thus the elevated blood pressure group displayed not only higher resting cardiovascular levels than normotensive subjects, but higher levels of metabolic activity too. With regard to change in physiological activity from rest to task, the group with mildly elevated blood pressure showed reliably larger increases in heart rate to the mental arithmetic task than the normotensive subjects. These effects, however, were not paralleled by group differences in metabolic activity increase. Physiological measures were also taken prior to and during graded dynamic exercise. The subsequent calculation of individual heart rate-oxygen consumption exercise regression lines allowed the comparison of actual and predicted heart rates during psychological challenge. The subjects with mildly elevated blood pressure displayed significantly greater discrepancies between actual and predicted heart rate values than normotensives during the psychological tasks in general and menta¹ arithmetic in particular. Group differences in physiological activity during exercise largely reflected the pattern seen at rest. A possible exception here was systolic blood pressure. Not only were systolic blood pressure levels higher throughout the exercise phase for mildly elevated blood pressure subjects, but this group evidenced more of an increase from rest to exercise than the normotensives.     

Are Cardiovascular Responses to Behavioral Stressors a Stable Individual Difference Variable in Childhood?

The present paper reports two studies which address the extent to which cardiovascular responses to behavioral stress can be conceptualised as a stable individual difference variable in children. In the first study, eighth grade girls (mean age = 14.2 yrs) who had participated in a study of the familial aggregation of cardiovascular responses to behavioral stress were asked to repeat the assessment protocol when they were in (he ninth grade (mean age = 15.1 yrs). Results showed that mean task-induced increases in diastolic blood pressure and heart rate during serial subtraction, mirror image tracing, and isometric handgrip tasks were reliable across test sessions, particularly due to the reliable increases exhibited during the mirror image tracing task. In the second study, fifth grade boys (mean age = 10.4 yrs) who had participated in a previous experiment (Matthews & Jennings, 1984) of cardiovascular responses during a video game were tested in the ninth grade (mean age - 14.0 yrs) in the protocol used in Study 1. Results showed that mean tusk-induced increases in diastolic blood pressure and heart rate during video games were related to mean task-induced increases during serial subtraction, mirror image tracing, and isometric handgrip tasks over three years Liter. The association for heart rate increases during the video game and isometric handgrip task was particularly impressive. These results suggest that task-induced diastolic blood pressure and heart rate responses of children are stable over substantial periods of time and amiss important developmental transitions, and generalize across tasks requiring qualitatively different behavioral responses. Nonetheless, future research is needed in adults and children to further identify factors which influence the stability and generalizability of cardiovascular responses to behavioral stress.     

Race, Parental History of Hypertension, and Patterns of Cardiovascular Reactivity in Women

This study examined the interaction of race and parental history of hypertension on patterns of cardiovascular responses among women. Two stressors were used that produce different patterns of cardiovascular reactivity: mental arithmetic, primarily a beta-adrenergic stimulus, and the cold face stimulus, which evokes alpha-adrenergic (i.e. vascular) activity. Systolic and diastolic blood pressure, heart rate, forearm blood flow, and forearm vascular resistance were assessed before, during, and after arithmetic and cold face stimulus. Both tasks produced the expected patterns of cardiovascular adjustment, although no Black-White differences occurred during arithmetic. However, Black subjects did show a slower recovery of diastolic blood pressure following arithmetic. The cold face stimulus produced significantly greater changes in systolic blood pressure in the Black than in the White women. Parental history of hypertension did not relate significantly to reactivity. The results provide limited support for the idea that Black females exhibit a greater pressor response than White females to a stimulus that produces primarily vascular rather than cardiac changes. These findings are discussed in relation to previous findings with males and with respect to their implications for the role of reactivity in Black-White differences in hypertension prevalence.