Individual Differences In Cardiovascular Reactivity Research Articles

Ambulatory Blood Pressure Reactivity as a Moderator in the Association Between Daily Life Psychosocial Stress and Carotid Artery Atherosclerosis.

We examined whether associations between daily psychosocial stressor exposures and carotid artery intima-medial thickness (IMT) may be stronger among those showing larger stress-related cardiovascular reactivity (CVR) during the course of daily living. A total of 474 healthy working adults (ages 30-54 years) collected ambulatory blood pressure and recorded their daily experiences, using electronic diaries, during two 2-day periods for a week. Measures of mean momentary task strain and social conflict were used as indices of stressor exposure, and partial regression coefficients linking momentary strain and conflict with ambulatory blood pressure fluctuations were used as measures of CVR. IMT was assessed in the carotid arteries using B-mode ultrasound. After covariate adjustment, associations between mean task strain exposure and IMT were significant among those high in CVR to strain (for systolic blood pressure, p = .006, for diastolic blood pressure, p = .011) but not among those low in strain CVR. Similarly, associations involving mean conflict exposure were significant among those high in CVR to social conflict (p < .001 for systolic blood pressure, p = .001 for diastolic blood pressure) but not among low social conflict reactors. Significant moderation effects were more consistently shown for task strain than for social conflict, but the overall pattern of results was robust across two different types of statistical modeling procedures. Individual differences in CVR may moderate the effects of daily psychosocial stress on subclinical CVD among healthy employed adults. Using ecological momentary assessment to measure stress exposure as well as stress reactivity may facilitate our ability to detect these effects.

The role of working memory capacity in cardiovascular monitoring of cognitive workload

Cardiovascular measures have been found to be sensitive to task onset and offset, but are less sensitive to adjacent levels of increasing cognitive workload. A potential confound in the literature is the disregard of individual differences in cardiovascular reactivity. In particular, the individuals‘ working memory capacity (WMC) is likely to play a role in cardiovascular reactivity to workload. A total of 98 university students performed four cognitive tasks that varied in their level of workload. The operation span (OSPAN) task was used to measure the participants‘ WMC. A variety of cardiovascular measures were gathered in real time during the experiment. Derived measures of blood pressure regulation were also calculated. In line with what was hypothesized, cardiovascular measures detected workload onset and offset but did not consistently distinguish between the individual task levels. Furthermore, a significant interaction between workload levels and WMC showed that cardiovascular profile varied depending on WMC scores. In addition, WMC negatively predicted subjective ratings of task difficulty as well as task performance, with subjective estimation of task difficulty and error increasing as WMC decreased. The results suggest that WMC may play a critical role in determining how individuals react to increased cognitive workload.

Blood pressure reactivity predicts somatic reactivity to stress in daily life

The purpose of the present study was to examine whether stress-somatic symptom associations may be more pronounced among individuals whose bodies exhibit higher levels of cardiovascular reactivity to a laboratory social stress task. During an initial laboratory session, participants delivered a 5-min speech and individual differences in cardiovascular reactivity were quantified. The same participants subsequently completed a 15-day experience sampling protocol, in which daily levels of stress and somatic symptoms were assessed. Multi-level modeling was used to assess associations among laboratory cardiovascular reactivity, daily stress and somatic symptoms. Daily symptom reports included a set of commonly experienced physical symptoms reflective of general bodily dysfunction. Individuals displaying high levels of laboratory systolic blood pressure reactivity experienced more somatic symptoms on high-stress days, but this was not the case for individuals low in systolic blood pressure reactivity. The results bridge two hitherto distinct health psychology literatures showing that cardiovascular and somatic reactivity to stress are associated. Stress reactivity individual differences in one system may indicate more general differences in bodily reactivity across systems.

Interpretations of ambiguous social situations and cardiovascular responses in adolescents

Previous research has documented effects of ambiguous outcome social situations on individual differences in cardiovascular reactivity in laboratory contexts. This study tested whether interpretations of ambiguous social situations are associated with daily life cardiovascular responses using ambulatory approaches. There were 206 high school adolescents assessed on interpretations of ambiguous social situations in the laboratory who then completed ambulatory monitoring of blood pressure (BP) and heart rate (HR) for 2 days. Adolescents who perceived threat during ambiguous situations exhibited higher systolic BP when talking to others compared to occasions of not talking with anyone, whereas the opposite was true for those with low threat perception. For high-threat adolescents, higher systolic BP was found when interacting with friends, whereas for low threat adolescents, lower systolic BP was found when interacting with parents. Greater threat interpretations were also associated with elevated HR at night. Understanding how adolescents perceive social interactions may help in gauging their daily cardiovascular responses.

Adaptation to Social Adversity Is Associated With Stroke Incidence

Laboratory-based studies have suggested that individual differences in cardiovascular reactivity and stress adaptive capacity are associated with stroke incidence. We test the hypothesis that sense of coherence (SOC), a marker of social stress adaptive capacity, is associated with incident stroke in a population-based prospective cohort study. A total of 20,629 participants, aged 41 to 80 years, in the UK European Prospective Investigation into Cancer (EPIC)-Norfolk study, who had not previously experienced a stroke, completed assessments that included SOC and details of their experience of life events during adulthood. An index of adaptation was constructed from responses to questions concerning over 80,000 adverse life events. During 145,000 person-years of follow-up (mean 7.1 years), 452 participants experienced either a fatal or nonfatal stroke event. A strong (as opposed to a weak) SOC was associated with a reduced rate of stroke incidence (rate ratio 0.76; 95% CI, 0.60 to 0.96) after adjustment for age, sex, pre-existing myocardial infarction, diabetes, hypertension treatment, family history of stroke, cigarette smoking, systolic blood pressure, obesity, social class, education, hostility and depression. No sex difference in this association was observed. Measures of social adversity occurrence and impact were not associated with stroke incidence, whereas faster reported adaptation to adverse event exposure was associated with a reduced rate of stroke incidence (rate ratio 0.89; 95% CI, 0.81 to 0.98; per standard deviation change in adaptation score, adjusted for age and sex). Stress adaptive capacity is a potentially important candidate risk factor for stroke.

Is There a Functional Neural Correlate of Individual Differences in Cardiovascular Reactivity?

The present study tested whether individuals who differ in the magnitude of their blood pressure reactions to a behavioral stressor also differ in their stressor-induced patterns of functional neural activation. Sixteen participants (7 men, 9 women aged 47 to 72 years) were classified as high (n = 8) or low (n = 8) blood pressure reactors by the magnitude and temporal consistency of their systolic blood pressure (SBP) reaction to a Stroop color-word interference stressor. Both high and low SBP reactors completed this Stroop stressor while their task-related changes in blood pressure and functional neural activity were assessed in a blocked functional magnetic resonance imaging design. In both high and low SBP reactors, the Stroop-stressor engaged the anterior cingulate, orbitofrontal, insular, posterior parietal, and the dorsolateral prefrontal regions of the cortex, the thalamus, and the cerebellum. Compared with low reactors, however, high reactors not only showed a larger magnitude increase in SBP to the Stroop stressor, but also an increased activation of the posterior cingulate cortex. A behavioral stressor that is used widely in cardiovascular reactivity research, the Stroop stressor, engages brain systems that are thought to support both stressor processing and cardiovascular reactivity. Increased activation of the posterior cingulate, a brain region implicated in vigilance to the environment and evaluative emotional processes, may be a functional neural correlate of an individual's tendency to show large-magnitude (exaggerated) blood pressure reactions to behavioral stressors.

Blood pressure reactivity and marital distress in employed women.

The impact of marital distress on cardiovascular responses to an "ecologically valid" laboratory stressor (a marital conflict recall task) was examined in maritally distressed and non-distressed women. It was hypothesized that the presence of high levels of marital distress would be associated with elevated blood pressure and heart rate responses to a marital conflict task. Fifty married, employed women, aged 25-45, were recruited into high and low marital distress groups, based on total scores on the Dyadic Adjustment Scale. Subjects participated in three laboratory stress tasks: a marital conflict recall task, a work conflict recall task, and a serial subtraction task. During the marital conflict recall task, women characterized as high in marital distress exhibited higher systolic blood pressure (M = 21.4 +/- 9.1 vs. 17.3 +/- 7.7) (p < .05) and heart rate (M = 13.6 +/- 9.5 vs. 10.9 +/- 6.5) (p < .01) responses, compared with low-distress women. However, the association between marital distress and cardiovascular response was statistically significant only after aggregate responses to the control stressors were used as covariates. These data indicate that the stress associated with recalling a marital conflict was manifest in elevated blood pressure and heart rate, particularly among women characterized as experiencing high levels of distress in their marriage. Future research is needed to determine whether the blood pressure differences between women who are satisfied with their marriage, versus those that are chronically distressed are clinically meaningful. In addition, examination of the "ecological validity" of laboratory stressors suggests that a useful methodology may be to assess task responses, while controlling for nonspecific individual differences in cardiovascular reactivity.

Segregation analysis of cardiovascular reactivity to laboratory stressors.

To better understand the contribution of major gene influences to individual differences in cardiovascular reactivity, we performed a segregation analysis on blood pressure responses to two laboratory tasks, mental arithmetic and bicycle exercise. The study population consisted of 1,451 adults (age > or = 18 years) who were members of 81 Utah pedigrees. Only 864 members performed the bicycle task because persons age 60 years or older or with heart disease were excluded. Blood pressure reactivity to mental arithmetic was defined as change from resting values, and reactivity to the bicycle task was defined as the difference between maximum blood pressure during exercise and resting values adjusted for the individual's workload. Complex segregation analysis and likelihood procedures were used to test for a major gene effect controlling blood pressure reactivity to each task. Two modifiers of the penetrance, age and sex, were considered parameters in these models. We found that diastolic blood pressure (DBP) but not systolic blood pressure reactivities to the mental arithmetic and bicycle exercise tasks were controlled by major gene effects. The best-fitting model, however, differed for the two tasks. For DBP reactivity to mental arithmetic, a major codominant model with gene frequency 0.10 was the best-fitting model; for the bicycle task, the best-fitting model was a mixed recessive model with gene frequency 0.21. Sex differences in DBP reactivity were significant in both tasks: the effect of age was significant only for the mental arithmetic task. These results suggest a significant genetic component for DBP reactivity to laboratory stressors.

Individual differences in cardiac sympathetic control predict endocrine and immune responses to acute psychological stress.

Potential mechanisms coordinating individual differences in cardiovascular reactivity and endocrine and immune responses to acute psychological stress were examined. Twenty-three young, healthy women performed a mental arithmetic challenge while measures of cardiovascular, endocrine, and immune function were assessed. Results revealed that the acute stressor was associated with changes in the cardiovascular, endocrine, and immune systems. More important analyses revealed that individual differences in cardiovascular reactivity predicted stress-induced cortisol changes. Furthermore, cardiac sympathetic control, as indexed by preejection period, was specifically related to changes in natural killer cell activity. These results suggest that distinct physiological pathways are activated in response to acute psychological stress.

A multidimensional measurement model for cardiovascular reactivity: stability and cross-validation in two adult samples.

The factor structure for measures of stress-related cardiovascular reactivity was examined in 2 samples: a university campus employee sample (N = 72) and a sample of young adult twins (N = 113). In both samples, 5 noninvasive cardiovascular measures were monitored during a series of challenging laboratory tasks. We developed a 2-factor model depicting vascular and cardiac influences on responding. With confirmatory factor analysis, this model was shown to be consistent with the data across both samples, across 2 testing sessions, and across 2 sets of tasks. Latent variables measuring cardiac and vascular reactivity were highly reliable on retest as well. Individual differences in cardiovascular reactivity to mental stress may be characterized by a stable, 2-dimensional pattern of response.

Recent developments in the study of cardiovascular reactivity: contributions from psychometric theory and social psychology.

Two related ongoing research programs are described. The first examines optimal measurement strategies for assessing individual differences in cardiovascular reactivity, and the second investigates the effects of the social environment as a moderator of cardiovascular responding during psychological challenge. Models and evidence from related behavioral sciences (Psychometric Theory and Social Psychology, respectively) have provided useful guidance for this work. Relevant background and current data examining the measurement and determinants of cardiovascular reactivity are reviewed, with a focus on these multidisciplinary contributions. The implications of the work for the construct of reactivity and its possible role as a marker of disease risk are discussed.

Patterns of autonomic response during laboratory stressors.

The present study was designed to include an index reflecting the influence of parasympathetic nervous system activity on the heart, respiratory sinus arrhythmia, in addition to measures reflecting primarily sympathetic nervous system activity. The inclusion of the parasympathetic index was considered important for two reasons:(a) Past studies have suggested different patterns of autonomic response to qualitatively different laboratory stressors but have had to infer parasympathetic influences more indirectly, and (b) there is evidence that borderline hypertensives may have reduced vagal tone at rest when compared to normotensives. This last point is important for the study of individual differences in cardiovascular reactivity because excessive responsiveness in young normotensives (beta-adrenergic reactors) has been suggested as a model for studying the precursors of some types of hypertension. Fifty-one male college students were given a reaction time task, a mental arithmetic task, a cold pressor task, and graded bicycle exercise. A variety of cardiovascular and respiratory measures were collected on each subject. Results indicated significant differences in levels of respiratory sinus arrhythmia during the three tasks and the rest period, giving additional evidence for parasympathetic differences (along with sympathetic differences) in these conditions. Additionally, high beta-adrenergic reactors did not differ in mean level of respiratory sinus arrhythmia from low reactors either at rest or during the task periods. These results are discussed in the context of previous research.

Conditioned and unconditioned cardiovascular reactivity: Predictability and stability over time

Two aspects of cardiovascular reactivity are distinguished: Unconditioned Reactivity (UCR) on the one hand and Conditioned Reactivity (CR) on the other hand. Both aspects of reactivity were operationalized by the a priori classification of changes of discriminative cardiovascular responses (heart period, finger pulse amplitude, pulse transit time) observed in 50 Ss (40 experimental group Ss, 10 controls) during the course of a discriminative conditioning session. Ss who showed a distinct reaction to the unconditional stimulus (UCS: aversive auditory noise) in the acquisition phase as well as towards the conditional stimulus (CS+: green light) in the extinction phase were assigned to the CR type, Ss who displayed reactivity only in the actual confrontation with the UCS in acquisition to the UCR type. Two further types of reactivity with the common characteristics of low responsiveness to the UCS were defined. The reactivity types defined on the basis of their cardiovascular response patterns could be differentiated through independently obtained criteria. Both of the high reactivity types (CR and UCR) obtained higher anxiety scores (state and trait) than the low reactivity types. The CR type differed from the UCR type in slightly higher introversion scores and in higher state anxiety as well as in more distinct anticipatory cardiovascular activation, all prior to conditioning. In a follow-up study arranged as a replication of the extinction phase of the conditioning session 22 months apart in time, conditioned cardiovascular responses were still observed for Ss of the CR type. No such after-effects could be found for either Ss of the UCR type or for those of the low reactivity types. These results may be relevant for hypotheses regarding the participation of learning processes in the formation of individual differences in cardiovascular reactivity as a possible risk factor for cardiovascular disease.

Cardiovascular stress reactivity: A behavior-genetic perspective

Increasing attention is being given to cardiovascular reactivity as a marker and potential risk factor for disease. Individual differences in cardiovascular reactivity to laboratory stress have been assessed in hypertensive adults and matched normotensive controls, in the normotensive offspring of hypertensive parents, and in twin-family studies of normotensive adolescents and adults. Cardiovascular stress reactivity is a relatively stable characteristic of individuals, and exaggerated stress-responsivity, associated with a positive family history of essential hypertension, is demonstrable early in life. Classic twin studies document significant genetic influences on cardiovascular stress patterns, and longitudinal studies suggest that heightened reactivity to stress constitutes a risk factor for the development of sustained hypertension. The study of stress reactivity may lead to early identification of young pre-hypertensive individuals who are candidates for behavioral and other nonpharmacologic intervention efforts.

Evaluation of beta-adrenergic influences on cardiovascular and metabolic adjustments to physical and psychological stress.

ABSTRACTThis study was designed to examine the hypothesis that certain behavioral demands may tend to trigger sympathetic mechanisms which result in metabolically excessive cardiac output elevations. Oxygen consumption and cardiac output adjustments during a contrived reaction‐time shock‐avoidance task were compared to a cold pressor test in healthy young male adults. The linear cardiac output/oxygen consumption relationship generated by performance on a graded exercise task was used to assess the metabolic appropriateness of cardiac output adjustments to the reaction‐time task and cold pressor. The reaction‐time task was generally found to evoke metabolically excessive increases in cardiac output, while cardiac output adjustments to cold pressor were more consistent with changes in metabolic demands. However, the tasks were associated with similar heart rate responses, with a significant attenuation in stroke volume during cold pressor accounting for the differential alterations in cardiac output. This finding suggests a limited reliability for heart rate as an index of cardiac performance. The effects of propranolol, which was employed to evaluate the role of sympathetic influences, indicated that beta‐adrenergic mechanisms were responsible for mediating the cardiac output response to the reaction‐time task, but only partially contributed to the cold pressor response. Post‐hoc analyses of individual differences in cardiovascular reactivity to the reaction‐time task suggest that, for hyperreactive individuals, the coping responses evoked by this task may lead to tissue overperfusion with oxygen, thereby providing a stimulus for autoregulatory vascular reflexes which may be associated with the etiology of hypertensive disease.

Stability of individual differences in cardiovascular reactivity: A thirteen month follow-up

This study concerns the stability of individual differences in cardiovascular reactivity among nineteen male subjects who had participated in a similar investigation thirteen months earlier. In the previous study (Year I), subjects were presented a frustrating task in concept formation to perform at each of two experimental sessions, scheduled one week apart, and recordings of heart rate (HR) and systolic and diastolic blood pressure (SBP, DBP) obtained during periods of rest and task performance on each occasion of testing. Under the current procedure (Year II), subjects were exposed to the same experimental stressor as on year I, as well as a second cognitive task involving a difficult problem in “mental arithmetic”; HR, SBP and DBP were again recorded both at rest and while subjects performed the instructed tasks. Measures of task-related cardiovascular arousal across the two years of observation revealed reproducible individual differences with respect to the magnitude of subjects' HR and SBP, but not DBP, reactivity. Although individual differences in HR and SBP responses correlated positively, neither HR nor SBP reactivity covaried reliably with DBP changes. It was suggested that concomitant response differences in HR and SBP, as observed under these experimental conditions, may reflect an underlying dimension of individual differences in beta-adrenergic reactivity.

Stability of individual differences in cardiovascular reactivity

Examining the stability of individual differences in cardiovascular reactivity, 42 male subjects were presented a difficult cognitive task to perform at each of two experimental sessions, scheduled 1 week apart, and recordings of hear rate and systolic and diastolic blood pressure obtained during periods of rest and task performance on each occasion of testing. Measures of task-related arousal (reactivity) across the two experimental sessions revealed substantial and reliable individual differences on all three response variables, as evidenced by (1) subsets of subjects representing clearly differentiated groups of Reactors and NonReactors on each measure and (2) correlation of reactivity scores of all subjects between the first and second sessions. While individual differences in systolic blood pressure and heart rate reactivity correlated positively, magnitude of systolic and diastolic blood pressure responses did not covary reliably among subjects. It was concluded that the present data demonstrate consistency, or reproducibility, of idiosyncratic cardiovascular reactivity and suggested that the variability of relationships among response measures may reflect more basic dimensions of individual differences involving neuroregulatory mechanisms underlying cardiovascular adjustments.