Stimulus-Specific Patterns of Cardiovascular Reactivity in Type A and B Subjects: Evidence for Enhanced Vagal Reactivity in Type B

Recent evidence suggests that the differences in cardiovascular reactivity between individuals exhibiting the Type A behavior pattern and those that do not are not limited to excessive betaadrenergic reactivity in Type A's. Research also suggests the possibility of a tendency for enhanced alpha-adrenergically and vagally mediated cardiovascular reactivity in Type B's. In the present study, Type A and Type B subjects were exposed to stressor stimuli known to elicit either betaadrenergic or alpha-adrenergic and vagal responses in the cardiovascular system. Heart rate, blood pressure, and forearm blood flow and vascular resistance responses were measured. The two Types did not differ in response to the beta-adrenergic stimulus (mental arithmetic). However, the alpha-adrenergic/vagal stimulus (cold face stimulus) produced more prolonged heart rate and blood flow responses in Type B subjects. Results suggest that Type B's show hyperreactivity (compared to Type A) when alpha-adrenergic or vagal cardiovascular responses are elicited. The nature of this hyperreactivity suggests possible mechanisms for reduced cardiovascular disease risk in Type B individuals.     

The Effects of Menstrual Cycle Phase on Cardiovascular and Pulmonary Responses to Behavioral and Exercise Stress

The present study was designed to compare the differential cardiopulmonary and hemodynamic responses of Type A and B women to an exercise and a psychological stressor. In addition, the effects of menstrual cycle phase on the resting and response levels of a wide range of physiological variables were explored. Thirty-two women participated in a progressive exercise stress test and a threat of shock video game during both the luteal and follicular phases of the menstrual cycle. Half of these subjects expressed the coronary-prone behavior pattern referred to as Type A, as assessed by the Jenkins Activity Survey. The remaining women were relatively free of these behaviors (Type B). Heart rate, oxygen consumption, carbon dioxide production, minute ventilation, and end-tidal carbon dioxide were monitored and recorded on a breath-by-breath basis. Systolic and diastolic blood pressure measures were taken at 2-min intervals. Results indicated similar baseline, exercise, and behavioral stress responses among Type A and B women. The stress responses were also the same between the follicular and luteal phases for all measured physiological variables. However, resting levels of heart rate, metabolism, and ventilation were all elevated at rest during the luteal phase. A regression analysis based on the exercise heart rate and oxygen consumption data demonstrated that a majority of subjects exhibited heart rate responses in excess of that expected during the psychological stressor. These data are discussed with special reference to possible mechanisms of the pathophysiology of cardiovascular disease.     

Interactive effects of type A personality and psychological and physical stressors on human cardiovascular functions

The first part of this study examined the relationship(s) between Type A behavior scores and heart rate, blood pressure and impedance derived cardiovascular measures in response to discrete stressors during a standardized psychophysiological assessment. Expts. 2A and 2B considered cardiovascular responses to dynamic exercise stress alone and in combination with psychological and cold pressor tests. Gender and stroke volume changes during the psychological stress correlated 0.45 (P less than 0.02) with Type A score. Subscale scores of Job Involvement correlated 0.78 (P less than 0.02) with stroke volume, total systemic resistance and heart rate during the psychological stressor, and systolic blood pressure during the cold pressor task. The combined effects of psychological stress and dynamic exercise on systolic and diastolic blood pressure were significantly greater than the individual effects of these stressors. The use of impedance cardiography in measuring cardiovascular variables that correlate with Type A behavior, during psychophysiological assessments, may further elucidate our understanding of Type A behavior in addition to providing information about how stress interacts with aerobic exercise.     

Ambulatory blood pressure monitoring and laboratory reactivity in type A behavior and components

Type A coronary-prone behavior has been characterized previously by cardiovascular hyperreactivity to laboratory stressors. The objectives of this study were: 1) to determine whether cardiovascular patterns under more naturalistic circumstances in the field were altered in Type A subjects, and 2) to determine whether these field patterns paralleled cardiovascular patterns to a series of stressors in the laboratory. Thirty-three healthy Type A and B men underwent 24-hr ambulatory blood pressure and heart rate monitoring during a normal day of activities. These subjects were also tested in the laboratory for blood pressure and heart rate responses to a series of stressor tasks: 1) cognitive (mental arithmetic), 2) perceptual motor (reaction time), and 3) physical (handgrip). Type A behavior and stylistic components were rated by structured interview. All studies were conducted double blindly. Type A subjects demonstrated greater cardiovascular reactivity to the laboratory cognitive stressor, but there was a mixture of differences between As and Bs in variability of ambulatory blood pressure and heart rate during different periods of the day. Yet, there were no differences in average blood pressure levels. The components of verbal competition and loudness of voice were positively associated with elevated average blood pressure and variability in the field, respectively, but not with laboratory hyperreactivity. Thus, this study confirmed laboratory-induced cardiovascular hyperreactivity in Type A behavior but, within its limitations, did not find a similarity between laboratory and field cardiovascular response patterns in these behavioral groups. The ambulatory blood pressure monitoring findings in the component groups may have prognostic significance and deserve further study.     

Heart Rate and Oxygen Consumption during Mental Arithmetic,a Video Game,and Graded Exercise: Further Evidence of Metabolically-Exaggerated Cardiac Adjustments?

Heart rate, plus various metabolic and ventilatory indices, were monitored while 20 young male subjects were exposed to a video game and a stressful mental arithmetic task. Measurements were also made while subjects undertook graded isotonic exercise. All measures changed as a function of psychological challenge, and during exercise physiological activity increased as an orderly function of workload. For each subject, heart rate was plotted against oxygen consumption over the various exercise loads. For the majority of subjects the analogous data points for the video game and mental arithmetic lay reliably above the exercise heart rate-oxygen consumption regression lines. When these regression lines were used to predict heart rate values during psychological challenge, the predicted values were significantly less than the values actually recorded for both tasks; although the discrepancy between predicted and actual values was on average greater with mental arithmetic, the difference was not statistically reliable. Pre-stressor baseline conditions were also associated with heart rate levels greater than predicted, albeit to a lesser extent. Finally, while both stressors produced heart rate adjustments additional to expectancies, inter-task consistency was low.     

Differential β- and α-adrenergic activation during psychological stress

The responsivity of several cardiovascular indices to a computerized mental arithmetic stress and a cold pressor stress were investigated in 22 healthy adult subjects. The major findings were that the largely β-adrenergically driven T-wave amplitude, pre-ejection period, R-wave to pulse interval, and left ventricular ejection time values responded only to mental arithmetic; a significant decrease in cardiac output and increase in peripheral resistance were elicited during the cold pressor test; inter-beat-interval and subjective stress ratings responded significantly to both stresses compared to baseline levels, but more intensely to mental arithmetic than the cold pressor test; blood pressure, stroke volume and the maximum of the first derivative of the raw impedance signal responded unspecifically to both stresses. These findings support the idea that cardiovascular responses to psychological challenge depend on the level of cognitive processing required for the task. In addition, the superfluity of multiple variable measurements to study cardiovascular reactivity in such situations is discussed.     

Heart Rate and Oxygen Consumption during Mental Arithmetic, a Video Game, and Graded Static Exercise

Heart rate, oxygen consumption, and respiratory activity were recorded while 18 young male subjects performed a stressful mental arithmetic task and played a video game. Measurements were also taken while subjects undertook a graded static leg lifting exercise. Physiological activity increased as an orderly function of exercise workload. For each subject, heart rate was plotted against oxygen consumption over the various exercise loads. Knowing oxygen consumption during the psychological tasks, these regression equations allowed the prediction of heart rate, and thus the computation of “additional” heart rate as the difference between actual and predicted heart rate. Overall predicted heart rate values were significantly less than the values actually recorded during the psychological tasks. However, whereas mental arithmetic was associated with “additional” heart rates of the same order as those observed in earlier research using graded dynamic exercise, the video game elicited decidedly less “additional” heart rate in the present case. The explanation for this lay in the regression lines; static exercise was characterized by heart rate-oxygen consumption regressions which were much steeper in terms of slope, as well as somewhat lower in terms of intercept, than those observed with graded dynamic exercise.     

Comparative effects of two beta-blockers on cardiovascular reactivity and type A behavior in hypertensives

This study compared the effects of beta-blockers differing in degree of central nervous system penetration on Type A behavior and cardiovascular reactivity to mental stress. Forty-six male hypertensives were assigned randomly to receive either highly lipophilic and nonselective propranolol, hydrophilic and cardioselective atenolol, the diuretic hydrochlorothiazide, or placebo. Subjects were administered parallel forms of the Structured Interview (SI) and performed mental arithmetic and a cognitive task prior to and after 6 weeks of therapy. Results indicated that diuretic and placebo subjects (subsequently combined into a single control group) did not differ and that both beta-blockers reduced heart rate but not blood pressure reactivity to mental stress (p less than 0.02), an effect that was strongest during the mental arithmetic test. Analysis of SI components indicated a reduction only in explosive speech for beta-blockers versus controls (p less than 0.05). For global SI classifications, seven out of 12 subjects (58%) receiving propranolol, three of 12 (25%) receiving atenolol, and four of 22 control subjects (18%) became less Type A (p less than 0.05). These data do not replicate results of a prior study obtained with atenolol and suggest that only a subset of hypertensive individuals show reduced Type A behavior with propranolol. Central nervous system mechanisms may be important in producing these effects.     

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.     

Psychological stress and metabolic control in patients with type I diabetes mellitus

Acute psychological stress is believed to cause disturbances of metabolic control in patients with Type I diabetes. To examine the validity of this assumption, we subjected nine healthy persons (mean [+/- SEM] blood glucose level, 74 +/- 2 mg per deciliter), nine patients with Type I diabetes who had normoglycemia (130 +/- 10 mg per deciliter), and nine diabetic patients with hyperglycemia (444 +/- 17 mg per deciliter) to two acute psychological stresses: mental arithmetic and public speaking. Subjects in the three groups were matched for age, weight, sex, and socioeconomic status. For all subjects, the mean increase in heart rate was 20 beats per minute while they were doing mental arithmetic and 25 beats per minute while they were speaking publicly (P less than 0.001). In all three groups, systolic and diastolic pressure rose markedly, the plasma epinephrine level increased by 50 to 150 pg per milliliter, and the norepinephrine level by 100 to 200 pg per milliliter under both stress conditions (P less than 0.001). The plasma cortisol level rose significantly after public speaking in all groups. Neither stress induced changes in circulating levels of glucose, ketones, free fatty acids, glucagon, or growth hormone. Thus, sudden, short-lived psychological stimuli causing marked cardiovascular responses and moderate elevations in plasma concentrations of catecholamines and cortisol are unlikely to disturb metabolic control in patients with Type I diabetes.     

Acute Emotional and Cardiovascular Effects of Stressful Mental Work During Aerobic Exercise

The acute effects of engaging in challenging mental work during a single session of aerobic exercise were examined on measures of subjective mood and cardiovascular function. Fifty-seven female subjects were randomly assigned to participate in either a 10-min aerobic exercise condition or a no-exercise control condition. Half of the subjects in each group performed digits backward problems during this time period, and no mental stressors were presented to the other subjects. The results indicated that the exercise and mental stress conditions had additive effects on subjective anxiety levels and on cardiovascular responses during exercise. Both exercise and mental stress increased heart rate. In addition, exercise had anti-anxiety and vasodilative effects, but both of these influences were attenuated by opposing main effects for mental stress exposure. No effects were found for exercise on measures of cardiovascular reactivity to a later digits backward stressor. The results are consistent with previous research in suggesting that exposure to mental stressors during aerobic exercise provides no acute psychological benefits but attenuates some of the mood improvements and vasodilative effects of the exercise activity.     

Exercise training in healthy type A middle-aged men: effects on behavioral and cardiovascular responses

Thirty-six healthy Type A men (means = 44.4 years) were randomly assigned to either an aerobic exercise training group or a strength and flexibility training group. Subjects completed a comprehensive psychological assessment battery before and after the exercise programs consisting of behavioral, psychometric, and psychophysiological testing. The behavioral assessment consisted of repeated Type A interviews that were videotaped for subsequent component analyses. The psychometric testing included two self-report questionnaires to assess Type A behavior. The psychophysiological test consisted of a standard behavioral challenge, a mental arithmetic task, performed while cardiovascular responses were monitored. Aerobic exercise (AE) training consisted of 12 weeks of continuous walking or jogging at an intensity of at least 70% of subjects' initial maximal oxygen consumption (VO2max) as determined by an initial treadmill test. Strength and flexibility (SF) training consisted of 12 weeks of circuit Nautilus training with no aerobic exercise. After 12 weeks of exercise, the AE group increased their VO2max by 15%, while the SF group did not change. Both groups experienced decreases in overt behavioral manifestations of the Type A behavior pattern and self-reported Type A traits. However, the AE group showed an attenuation of heart rate, systolic and diastolic blood pressure, and estimated myocardial oxygen consumption (MVO2) during the task and had lower blood pressure, heart rate, and (MVO2) during recovery. In contrast, the SF group showed a significant reduction only in DBP during the task, which was likely due to habituation. These results support the use of aerobic exercise as a method for reducing cardiovascular risk among healthy Type A men.     

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.     

Adrenocorticotropin responses to interpersonal stress: effects of overt anger expression style and defensiveness.

This study evaluated the influence of overt anger expression style and defensiveness on the hypothalamic-pituitary-adrenocortical (HPA) responses to acute psychological stress. These personality traits are thought to modulate the stress cardiovascular response and influence disease risk, however, little is known about their influence on HPA responses. Forty-six young, healthy male volunteers worked on counterbalanced extended public-speaking and mental arithmetic. The sample was dichotomitized into groups low vs. high in anger-out, using Spielberger's Anger-Expression Inventory, and in defensiveness, using the Marlowe-Crown Social Desirability Scale. Serum cortisol and adrenocorticotropic hormone (ACTH) concentrations were measured before and after performing each task. Heart rate (HR) and blood pressures (BP) were obtained continuously in 2-min intervals before, during and after the tasks. Public speaking produced greater adrenocortical and cardiovascular stress responses than mental arithmetic, and the greatest increases in ACTH occurred in subjects high in anger-out and defensiveness. These preliminary findings provide evidence that a mismatch between traits of preferred anger expression style and defensive style produces pronounced adrenocorticotropic responses during socially salient stress.     

Psychophysiological Response Patterns to Single, Double, and Triple Stressors

Synergistic activation elicited by multiple stressors as compared to single stressors has received little attention in the literature. In the present study, mental arithmetic, cold pressor, and physical exercise tasks were administered to 54 male subjects alone and in all possible simultaneous combinations. The dependent variables measured were heart rate, cardiac output, RZ-time, blood pressure, respiration rate, tidal volume, respiratory minute volume, oxygen uptake, oxygen equivalent, self-report data of psychological and somatic tension, pain ratings during the cold pressor test, and performance on mental arithmetic. Results for physiological variables indicate synergistic effects for stressor combinations as compared to single stressors, depending on the respective combination or variable. Contrary to this finding, psychological variables revealed ceiling and depressor effects. Response patterns to the different stressors showed only moderate similarity and exhibited stimulus-specific effects. Heart rate, diastolic blood pressure, and respiration rate were most appropriate in describing various response patterns.     

Cardiovascular reactivity, Type A behavior, and coronary heart disease: Comparisons between myocardial infarction patients and controls during laboratory-induced stress

Cardiovascular responses to a series of laboratory stressors were examined in middle-aged Type A and Type B men. The subjects were 30 patients with diagnosed myocardial infarction (NYHA Class 1) and 26 age-matched healthy controls. All subjects were nonsmokers in the normotensive range, and none were on medication. Blood pressure, heart rate, forearm blood flow and resistance, and impedance cardiography-determined response variables were obtained during performance and recovery periods of both mental and physical tasks. The patients showed elevated reactivity in systolic blood pressure and cardiac output and prolonged systolic lime ratio during mental stress tasks and elevated total peripheral resistance and lower cardiac output and stroke volume during physical tasks, as compared with control subjects. Thus, the difference in blood pressure reactivity between patients and controls appeared to be primarily dependent on the vascular component during physical tasks, whereas the mental tasks promoted a hemodynamic response pattern more consistent with beta adrenergic activation. Type A men, irrespective of coronary status, showed larger systolic and diastolic blood pressure response to both mental and physical stress than did Type B men.     

Cardiovascular responses in Type A and Type B men to a series of stressors

Fifty-six healthy adult males were administered the Type A Structured Interview and assessed as exhibiting either Type A (N=42) or Type B (N=14) behavior pattern. They were monitored for systolic (SBP) and diastolic blood pressure (DBP) and heart rate (HR) responses during a series of six challenging tasks: Mental Arithmetic, Hypothesis Testing, Reaction Time, Video Game, Handgrip, and Cold Pressor. The results indicated that Type A subjects exhibited greater cardiovascular responses than did Type B subjects during some (Hypothesis Testing, Reaction Time, Video Game and Mental Arithmetic) but not all (Handgrip and Cold Pressor) of the tasks. These results are discussed in terms of previously reported findings on conditions that do and do not produce differences in Type A/B cardiovascular stress responses. This research was supported by USPHS Grant MH-31269. We would like to thank Drs. Steve Manuck, David Krantz, Ted Dembroski, Curt Sandman, David Hothersall, and Gifford Weary for their helpful comments on an earlier draft of this paper.     

Cardiovascular activity during mental stress following vigorous exercise in sportsmen and inactive men

Thirty-six competitive sportsmen and 36 inactive men participated in a two-session experiment. Session 1 involved exercise to exhaustion so as to assess maximal oxygen consumption (V?o_{2 max}. In Session 2, both groups were randomized into three experimental conditions: 20 min of exercise at high intensity (70%V?o_{2 max}) or moderate intensity (50% V˙o_{2 max}) or a light exercise control. Following 30 min of recovery, all subjects performed mental arithmetic and public speech tasks in a counterbalanced order. Cardiovascular, electrodermal, respiratory, and subjective variables were recorded. Sportsmen had higher V˙o_{2 max}, lower body fat, and lower resting heart rate (HR) than inactive men. A postexercise hypotensive response was observed among subjects in the 70% and 50% V˙o_{2 max} conditions, accompanied by baroreceptor reflex inhibition in the 70% condition. Systolic pressure was lower during mental arithmetic and during recovery from the speech task in the high-intensity than in the control group. Diastolic pressure was lower following mental arithmetic in the high-intensity group. No differences in HR reactivity, electrodermal, or respiratory parameters were observed, but baroreceptor reflex sensitivity was inhibited during mental arithmetic. The results are discussed in relation to previous reports of suppressed cardiovascular reactivity to mental stress tests following vigorous exercise and the role of stress-related processes in the antihypertensive response to physical training.     

Consequence of Social Isolation on Blood Pressure,Cardiovascular Reactivity and Design in Spontaneously Hypertensive Rats

Spontaneously hypertensive rats (SHR), which inherently display exaggerated cardiovascular defence reactions to environmental stimuli (Hallbäck and Folkow 1974), and normotensive control rats (NCR) were kept isolated after they were weaned to reduce such environmental influences which normally induce psychological activation. Mean arterial pressure was followed until 7 months of age, when the cardiovascular defence reactions to acute mental stress were compared and an analysis of cardiovascular design was made. The isolated SHR but not the isolated NCR, had significantly lower pressures than their unisolated controls. Likewise, judged by the relative weight of the left ventricle and the hemodynamically evaluated design of the hindquarter resistance vessels, the structural cardiovascular adaptation was about proportionally less pronounced in isolated than in control SHR. However, their cardiovascular responses to acute “psychological stress” were equally intense, and clearly exaggerated when compared with NCR. Thus, a prolonged reduction of excitatory environmental influences implies a relatively less pronounced development of hypertension in SHR, even though an inherent hyperreactivity concerning neurohormonal pressor responses to alerting stimuli is present. These findings stress the importance of interacting intrinsic-hereditary and extrinsic neurogenic influences for the initiation of primary hypertension.     

The thrill of victory: Blood-pressure variability and the Type A behavior pattern

Winning and losing were predicted to be more significant in determining cardiovascular responses for Type A's than for Type B's. Twenty-four healthy, preclinical medical students (12 Type A and 12 Type B) were randomly assigned to be winners or losers at a competitive reaction-time task. Type A winners were different from all other subjects in maintaining initially high systolic blood-pressure levels. Rather than showing a pattern consistent with unusual stress, the Type A losers appeared to slow down in their reaction time and lose interest in the competition. It is suggested that the continued stimulation that Type A's get from successfully competing for rewards may be more important in cardiovascular terms than the stress of losing—at least for males. It is also suggested that activation of the Type A behavior pattern may be more elective than it is usually considered to be.