Verbal-autonomic response dissociations as traits?

Dissociations between subjective and physiological responses to stress are of central interest in coping research. However, little is known about their stability across situations and time. Two experimental sessions - separated by 1 year - were conducted to examine cross-situational consistency and longterm-stability of HR-derived and SCL-derived dissociation scores. In year 1, a speech stressor, the cold pressor and a video stressor (viewing of the speech video) were applied. In year 2, mental arithmetics, anagrams and a torture video were presented. Thirty-five students participated and HR, SCL and negative affect were recorded. For each stressor, standardized changes in negative affect were subtracted from changes in autonomic reactivity (HR and SCL, respectively). Dissociation scores were relatively consistent across the stressors with HR-derived scores exceeding SCL-derived scores. Longterm-stability proved acceptable (r=.61, P<.001 for HR-derived and r=.40, P<.05 for SCL-derived scores). In sum, verbal-autonomic response dissociations show considerable cross-situational and temporal stability and thus might be considered as traits.     

A comparative validation of sympathetic reactivity in children and adults

This study provides comparative data on cardiac reactivity to common laboratory tasks in preschool children (ages 4.5-5.5 years) and young adults. We used a series of tasks (an emotionally evocative video, interview, reaction time task, and cold forehead pressor) to examine whether pre-ejection period, a common estimate of sympathetic cardiac activity in adults, provides a comparable measure of sympathetic reactivity to these tasks in preschool children. Our results demonstrate that the cardiac reactivity (pre-ejection period, respiratory sinus arrhythmia, and heart period) to such tasks in children and young adults is similar, but with smaller sympathetic reactivity in children. The consistency of the reactivity across tasks within individuals and consistency of reactivity across children and young adults suggests that pre-ejection period is a reasonable estimate of sympathetic activity in children.     

Predicting Home and Work Blood Pressure Measurements from Resting Baselines and Laboratory Reactivity in Black and White Americans

The relationship between blood pressure in the laboratory (both at rest and in response to laboratory tasks) and ambulatory blood pressure at home and at work was evaluated. One hundred nineteen normotensive and unmedicated mild-moderate hypertensive black and white females and males participated in laboratory blood pressure monitoring at rest and during four challenging tasks (structured interview, video game, bicycle exercise, and cold pressor test) as well as ambulatory blood pressure monitoring while at home and at work. Baseline blood pressure taken while subjects were at rest was the strongest predictor of ambulatory systolic blood pressure (r = .64) and diastolic blood pressure (r = .77) at work. Among reactivity tasks the strongest predictors of ambulatory blood pressure in the total population were the structured interview and the video game (both psychological tasks) followed by the cold pressor test. Racial comparisons, however, determined that the cold pressor test predicted diastolic blood pressure significantly better for blacks (r = .73) than for whites (r = .40), suggesting a possible difference in blood pressure regulation.     

Secretory immunoglobulin A and cardiovascular reactions to mental arithmetic and cold pressor

Secretory immunoglobulin A (sIgA) in saliva and cardiovascular reactions to mental arithmetic and cold pressor tasks were recorded in 16 healthy young men on two sessions, 4 weeks apart. Both tasks elicited significant increases in sIgA secretion rate, reflecting increases in both salivary volume and sIgA concentration. Whereas mental arithmetic elicited a mixed pattern of alpha- and beta-adrenergic cardiovascular reactions, the pattern of reactions to cold pressor was predominantly alpha-adrenergic. Task levels of sIgA secretion rate, sIgA concentration, and saliva volume showed moderate to high test–retest reliability ( r = .52–.83), although test-retest correlations were less impressive for change scores ( r =−.19–.53). The pattern of correlations between change in sIgA secretion rate and cardiovascular reactivity variables was inconsistent.     

Generalization of cardiovascular response: supportive evidence for the reactivity hypothesis.

Cardiovascular responses were monitored while 36 subjects completed a battery of laboratory stressors comprising mental arithmetic, a reaction time task, a speech task, and the forehead cold pressor. Inter-task consistency was assessed for each of 6 physiological parameters for all task pairings. Considerable inter-task consistency for reactivity scores was seen among the psychological stressors for all variables. The question of such consistency between the cold pressor and the psychological tasks was then addressed. The pattern of consistency was not as clear-cut in this case. For systolic blood pressure and pre-ejection period, reactivity scores to the cold pressor did not correlate with those to any of the psychological tasks. In contrast, cardiac output and total peripheral resistance responses showed considerable consistency. The importance of determining the nature of the relationship between psychological and physical stressors is discussed.     

Temporal consistency of individual differences in cardiac response to a video game

Three experiments are reported which examined the temporal stability of cardiac reactions to a video game of the 'space invaders' genre. Experiment 1 also addressed the matter of inter-task consistency; in addition to the video game, subjects were presented with an unsignalled reaction time task and led to believe that relatively quick reactions attracted financial reward, while slower ones brought either a burst of loud noise or withdrawal of money previously earned. Forty-two male subjects were tested on both tasks on two occasions, a week apart. Of the two tasks, the video game elicited the greater reactivity. In addition, individual variations in reactivity showed striking temporal stability for both tasks. However, inter-task consistency was much less marked; in fact, a significant inter-task correlation was obtained only on the first occasion of testing. It is probable that limited consistency here was in some measure due to the ineffectiveness of our reaction time task in eliciting substantial reactivity. Finally, reactivity was independent of baseline heart rate level. In experiment 2, three extreme high and three extreme low cardiac reactors were selected from an initial sample of 23 male subjects, on the basis of reactivity during an initial session with the video game, and subsequently studied during four further sessions. Once more, impressive stability of heart rate reactivity was apparent over sessions. In experiment 3, we examined the reliability of individual variations in cardiac reactivity in women and the issue of whether temporal stability is constrained by menstrual cycle effects. Twenty-four females were tested on the video game both preovulatory and postovulatory, with half being tested first during the preovulatory phase and half being tested first during the postovulatory phase. Again, the most striking finding was the marked stability of individual variations in cardiac reactivity over both time and menstrual cycle phase.     

Hemodynamic profile of stress-induced anticipation and recovery.

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

For Distinguished Early Career Contribution to Psychophysiology: Award Address, 1988

This program of experiments examined heart rate responses to mental arithmetic and a video game. Attention first focused on their metabolic relevance. Comparison with heart rate/oxygen consumption regression equations generated from isotonic exercise data revealed that the heart rate increases of certain individuals were considerably in excess of those necessitated by contemporary metabolic demand. Both temporal and intertask consistency of reaction were explored, and supportive evidence was obtained. The relationship between laboratory and real-world reactions was investigated, and preliminary evidence found suggesting that in-laboratory responses are indicative of responses to more naturalistic stressors. Finally, twin studies examining the genetic and environmental determinants of individual differences in heart rate change during the tasks revealed a substantial genetic component for these responses.     

Pediatric impedance cardiography: temporal stability and intertask consistency

The pathogenic processes responsible for cardiovascular disease have their origins in childhood. Although children's measures of heart rate and blood pressure have been found to be reliable, the reliability of impedance cardiography derived measures have not been evaluated. Thirty-three children, ages 8-11 participated in two sessions. Stressors included serial subtraction, isometric handgrip, and mirror-image tracing. Results indicated the impedance measures showed moderately high temporal stability (average scores r(avg) = .74; difference scores r(avg) = .53) and intertask consistency (average scores r(avg)= .78; difference scores r(avg)= .53). Blood pressure demonstrated the lowest reliability; Heather index, preejection period, and stroke volume demonstrated the highest. These findings suggest children's cardiovascular reactivity to laboratory stressors can be reliably and consistently assessed using impedance cardiography.     

Autonomic characteristics of defensive hostility: reactivity and recovery to active and passive stressors.

The autonomic characteristics of hostility and defensiveness were assessed in 55 male undergraduates based on composite Cook Medley Hostility (Chost) and Marlowe Crowne Social Desirability (MC) scores to create 4 groups: Defensive Hostile (DH; high MC, high Chost), High Hostile (HH; low MC, high Chost), Defensive (Def; high MC, low Chost) and Low Hostile (LH; low MC, low Chost). All subjects engaged in a video game (VG) and hand cold pressor (CP) task. Cardiovascular responses in DH subjects were predicted to show enhanced sympathetic alpha and beta-adrenergic activity and the least vagal control compared to others across tasks. DH and LH men showed significant heart rate reactivity to the CP task compared to HH men. LH men showed significant reductions in high frequency power (vagal assessment) to the tasks compared to HH men. Future studies may employ harassment techniques and include the factors of gender and ethnicity in their assessments.     

1-Year stability and prediction of cardiovascular functioning at rest and during laboratory stressors in youth with family histories of essential hypertension

Blood pressure (BP). heart rate, cardiac index, and total peripheral resistance index were measured at rest and in response to postural change, forehead cold stimulation, and a video game challenge in a sample of 128 White and 155 African-American normotensive youth with family histories of essential hypertension (EH). These measurements were readministered 1 year later (12.5 +/- 3.2 months). Moderate temporal stability was observed for all resting and absolute stress responses. Reliability estimates for reactivity change scores were lower, although some were within acceptable ranges. African-American youth exhibited greater BP and peripheral resistance index reactivity to forehead cold on both evaluations. After controlling for various anthropometric and demographic parameters and the pertinent previous year's resting cardiovascular (CV) parameter, mean video game systolic blood pressure (SBP) responses were predictive of resting SBP whereas absolute forehead cold and video game diastolic responses predicted resting diastolic blood pressure (DBP) 1 year later. Mean video game DBP responses were also predictive of resting peripheral resistance index after controlling for significant demographic and anthropometric measures. CV reactivity is discussed with regard to possible value in prediction of changes in resting BP and cardiac structure prior lo establishment of EH.     

Laboratory stress testing to assess real-life cardiovascular reactivity

Thirty-six normotensive adults received laboratory stress testing (mental arithmetic, short-term memory, isometric handgrip, cold pressor tests) and 24-hour ambulatory blood pressure monitoring on two work days separated by a month. Laboratory and ambulatory measures of cardiovascular reactivity had low test-retest reliability. Increases in blood pressure during the memory and cold pressor tests were related to measures of reactivity obtained outside the laboratory (waking blood pressure variability, responses to home and work environments). However, the portion of ambulatory reactivity accounted for by laboratory reactivity was small. In the best case (r = 0.43), cold pressor diastolic pressure explained only 19% of diastolic pressure variability in the natural environment. Laboratory-ambulatory disagreement in reactivity was related to interindividual variability in physical activity on the day of ambulatory monitoring.     

Quantifying rapid changes in cardiovascular state with a moving ensemble average

MEAP, the moving ensemble analysis pipeline, is a new open‐source tool designed to perform multisubject preprocessing and analysis of cardiovascular data, including electrocardiogram (ECG), impedance cardiogram (ICG), and continuous blood pressure (BP). In addition to traditional ensemble averaging, MEAP implements a moving ensemble averaging method that allows for the continuous estimation of indices related to cardiovascular state, including cardiac output, preejection period, heart rate variability, and total peripheral resistance, among others. Here, we define the moving ensemble technique mathematically, highlighting its differences from fixed‐window ensemble averaging. We describe MEAP's interface and features for signal processing, artifact correction, and cardiovascular‐based fMRI analysis. We demonstrate the accuracy of MEAP's novel B point detection algorithm on a large collection of hand‐labeled ICG waveforms. As a proof of concept, two subjects completed a series of four physical and cognitive tasks (cold pressor, Valsalva maneuver, video game, random dot kinetogram) on 3 separate days while ECG, ICG, and BP were recorded. Critically, the moving ensemble method reliably captures the rapid cyclical cardiovascular changes related to the baroreflex during the Valsalva maneuver and the classic cold pressor response. Cardiovascular measures were seen to vary considerably within repetitions of the same cognitive task for each individual, suggesting that a carefully designed paradigm could be used to capture fast‐acting event‐related changes in cardiovascular state.     

Effects of anger/hostility, defensiveness, gender, and family history of hypertension on cardiovascular reactivity

In this study, we examined the combined effects of anger/hostility and defensiveness on reactivity to three stressors (math, handgrip, cold pressor) and how these effects are moderated by gender and family history of hypertension. The subjects were 209 college students. Low compared with high Spielberger anger-out scores were associated with greater diastolic blood pressure (DBP) reactivity in low-but not high-defensive women with a negative family history. High compared with low hostility scores were associated with greater heart rate reactivity in low-defensive men with an opposite effect in high-defensive men. Gender, family history, and defensiveness each affected differential DBP reactivity to the three tasks. Combined study of biological factors and coping styles can improve our understanding of cardiovascular reactivity and disease.     

The Relation Between Rhythmic Cardiovascular Variability and Reactivity to Orthostatic, Cognitive, and Cold Pressor Stress

Two groups of normotensive, male subjects having either a positive or negative parental history of essential hypertension were exposed to passive body tilt from horizontal to a 70° head-up posture, while systolic and diastolic blood pressure, heart period, and respiration amplitude were sampled on a beat-by-beat basis. Subjects also performed mental arithmetic and cold pressor tasks, and cardiovascular reactivity was expressed as change from baseline levels. The body tilt data were analyzed by cross-spectral analysis focusing on two frequency bands, one between .06-.1 Hz, and the other at the predominant breathing frequency. The two groups did not differ significantly in their basal levels of physiological activity or in their response to the tasks. Cross-spectral analysis identified tilt induced changes in the power spectra and coherence spectra within the two frequency bands. These changes differed between the two frequency bands and among the various physiological response systems investigated. Larger rhythmic oscillations in heart period within both frequency bands predicted greater cardiovascular reactivity to the mental arithmetic task but not the cold pressor task. The results are discussed in terms of neural control mechanisms (e.g., vagal tone) implicated in the dynamic regulation of cardiovascular function during psychophysiological states such as stress.     

Cardiovascular recovery from stress predicts longitudinal changes in blood pressure

Cardiovascular reactivity and recovery were examined as predictors of blood pressure changes over 3 years. Blood pressure and heart rate readings were obtained from 73 men and women aged 18-20 years during cold pressor, mental arithmetic, tourniquet ischemia, cycle exercise and step exercise tasks. Regression analyses indicated that after adjustment for initial blood pressure, initial age, initial body-mass index, sex, parental history of hypertension, and length of follow-up, heightened heart rate reactivity to mental arithmetic was associated with increased follow-up systolic blood pressure (DeltaR(2)=0.04, P<0.05). Systolic blood pressure recovery from cold pressor and tourniquet ischemia were also positively related to follow-up systolic blood pressure (DeltaR(2)=0.04 and 0.04, respectively, P<0.05) and remained so even after adjustment for the corresponding cardiovascular reactivity measures. These findings suggest that cardiovascular reactivity and recovery measures are modest predictors of longitudinal changes in blood pressure.     

Longitudinal association of cardiovascular reactivity and blood pressure in Samoan adolescents

OBJECTIVE: The longitudinal association between blood pressure (BP) reactivity to a video game and resting BP 3 to 4 years later was investigated in 83 Samoan adolescents from American and (Western) Samoa as part of a multidisciplinary study of cardiovascular disease (CVD) risk in modern Samoans. METHODS: Participants ranged in age from 11 to 14 years at baseline, in 1992 to 1993, and 14 to 18 years at follow-up in 1996. Video game BP reactivity was defined as the residual score of the regression of the maximum BP during the video game on the minimum resting BP before the video game. The predictive effect of baseline video game BP reactivity on follow-up resting BP was tested using regression models with baseline resting BP, baseline body mass index (BMI), and age as covariates. RESULTS: Systolic BP reactivity to the video game at baseline was significantly, p=.04, and independently associated with resting systolic BP 3 to 4 years later. Samoan adolescents who had higher systolic BP reactivity scores at baseline had significantly higher resting systolic BP at follow-up after adjustment for the significant effects of baseline resting systolic BP, age, and BMI. There were no interactions between sex and reactivity or between residence, American Samoa or (Western) Samoa, and reactivity in the models, indicating that the effects of systolic BP reactivity in early adolescence on later adolescent resting systolic BP were similar in the entire study sample. CONCLUSIONS: Video game cardiovascular reactivity seems to assess aspects of psychophysiological arousal and prospective CVD risk in Samoan adolescents of both sexes residing in both Samoas, and may be useful for understanding the role of psychosocial stress and health in modernizing societies.     

The stress interview as a tool for examining physiological reactivity

Most studies of cardiovascular reactivity utilize tasks that are highly standardized and controlled. However, there is some concern whether the information obtained from these tasks is relevant to understanding the cardiovascular responses to behavioral stimuli encountered in real life. Historically, various forms of a stress interview have been used to examine physiological concomitants of emotional arousal. However, these tools fell into disuse because of ethical concerns, their intensive time requirements, and the perception that the interviews could not be standardized. We have developed a short (16-minute) interview that is not aversive or threatening. In studies on 24 normotensives and 19 hypertensives, the interview elicited greater blood pressure elevations than those elicited by mathematical calculations or cold pressor (p less than 0.0001). The interview increased systolic and diastolic pressures by 38/32 mm Hg in hypertensives and 31/24 mm Hg in normotensives. The variance in BP elicited by this interview is not appreciably greater than that found in highly structured tasks such as mathematical calculations. The test-retest stability of the interview is comparable to that of resting baseline blood pressure and is superior to that of mathematical calculations or cold pressor. Techniques such as the interview may be at least as useful as highly standardized tasks and possibly more valid as models for examining cardiovascular reactivity.     

Cardiovascular recovery from acute laboratory stress: reliability and concurrent validity

OBJECTIVE: We assessed the value of laboratory measures of cardiovascular recovery across four criteria: reliability across multiple tasks, reliability across a 3-year time interval, ability to predict daily ambulatory blood pressure, and interrelationships with coronary risk factors and psychosocial variables. METHODS: Three hundred twenty-nine healthy adults (mean age = 27.1 years) completed a two-part protocol consisting of 1 day of laboratory testing and 1 day of ambulatory monitoring. The laboratory protocol included a 15-minute baseline assessment followed by three 5-minute laboratory challenges (mental arithmetic, speech, and handgrip). Five-minute recovery periods followed each exercise. One hundred twenty-five participants returned after 3 years to repeat the protocol. RESULTS: When aggregated across tasks, cardiovascular recovery showed acceptable levels of internal consistency (alpha values = 0.7) and proved relatively stable across time (r values = 0.22-0.35). Recovery values statistically improved the prediction of daily ambulatory readings above baseline and stress reactivity laboratory values (p values < .001) but were largely unrelated to coronary risk factors or psychosocial measures. CONCLUSION: These results suggest that cardiovascular recovery from acute laboratory stress can be treated as a stable individual difference variable that can -improve standard laboratory-based predictor models of ambulatory readings.     

An alternative approach for achieving cardiovascular baseline: viewing an aquatic video.

Due to the importance of baseline and recovery levels in the computation of reactivity, two studies were conducted to determine an alternative method to traditional rest for achieving baseline and recovery levels of cardiovascular measurements. Watching a relaxing, aquatic video was compared with a traditional resting baseline to determine the better method for achieving low baseline levels. In addition, watching the video was compared with traditional rest during 5-min post-task recovery periods. Systolic (SBP) and diastolic blood pressure (DBP) decreased more during the baseline period when subjects viewed the video than when subjects rested quietly. Similarly, subjects displayed greater recovery following the mental tasks when they watched a video than when they merely sat quietly. It is recommended that researchers standardize baseline procedures by showing a relaxing video before administering tasks for the assessment of cardiovascular reactivity.