Laboratory reactivity assessment: effects of casual blood pressure status and choice of task difficulty

The Psychophysiological Differentiation of Actual, Imagined, and Recollected Mirth

Heart rate and galvanic skin response measures were recorded from 23 participants (10 men and 13 women) while mirth was elicited through use of imagination (Imagined Mirth), through recollection (Recollected Mirth), or through an experimental manipulation (Actual Mirth). An analysis of variance indicated significant differences for heart rate, F(2, 22) = 4.716, p = .0210, and for galvanic skin response, F(2, 22) = 4.779, p = .0201 among the three methods. Consistent with the hypotheses forwarded, both Imagined and Recollected Mirth generated significantly greater changes in psychophysiology than Actual Mirth. However, there were no significant differences found between Imagined and Recollected Mirth. The implications of these findings on current and future research are discussed.

Concurrent tobacco and khat use is associated with blunted cardiovascular stress response and enhanced negative mood: a cross-sectional investigation

OBJECTIVES

Khat (Catha edulis), an amphetamine-like plant, is widely used in East Africa and the Arabian Peninsula and is becoming a growing problem in other parts of the world. The concurrent use of tobacco and khat is highly prevalent and represents a public health challenge. We examined for the first time associations of the concurrent use of tobacco and khat with psychophysiological responses to acute stress in two sites in Yemen.

METHODS

Participants (N = 308; 135 women) included three groups: users of khat and tobacco, users of khat alone, and a control group (nonsmokers/nonusers of khat). These individuals completed a laboratory session in which blood pressures (BP), heart rate, and mood measures were assessed during rest and in response to acute stress.

RESULTS

Concurrent use of khat and tobacco was associated with attenuated systolic BP, diastolic BP, and heart rate responses to laboratory stress (ps < 0.05) and with increased negative affect relative to the control group (ps < 0.05).

CONCLUSIONS

Results demonstrated blunted cardiovascular responses to stress and enhanced negative affect in concurrent khat and tobacco users. These findings extend previous studies with other substances and suggest that adverse effects of khat use may lie in its association with the use of tobacco.

The heart contracts to reward: monetary incentives and preejection period

Wright's (1996) integration of motivational intensity theory (Brehm & Self, 1989) and Obrist's (1981) active coping approach predict that cardiovascular reactivity in active coping depends on the importance of success when task difficulty is unclear. Despite the support for this perspective, one of the basic hypotheses-the mediation of these effects by beta-adrenergic activity-has not been tested yet. To close this gap, participants worked on a delayed-matching-to-sample task and could earn either 1, 15, or 30 Swiss Francs for a successful performance. Results showed that preejection period reactivity-an indicator of beta-adrenergic impact on the heart-increased with increasing incentive value. Thus, this experiment closes a gap in the support of Wright's model by demonstrating that beta-adrenergic reactivity is associated with incentive value under conditions of unclear difficulty.

Task difficulty effects on cardiac activity

An experiment with 64 participants manipulated task difficulty and assessed cardiac reactivity in active coping over four levels of demand. Participants performed a memory task while preejection period, heart rate, and blood pressure were assessed. In accordance with the theoretical predictions of R. A. Wright's (1996) integration of motivational intensity theory (J. W. Brehm & E. A. Self, 1989) with Obrist's active coping approach (P. A. Obrist, 1981), preejection period and systolic blood pressure reactivity increased with task difficulty across the first three difficulty levels. On the fourth difficulty level-where success was impossible-reactivity of both preejection period and systolic blood pressure were low. These findings provide the first clear evidence for the notion of Wright's integrative model that energy mobilization in active coping is mediated by beta-adrenergic impact on the heart.

Violence exposure and optimism predict task-induced changes in blood pressure and pulse rate in a normotensive sample of inner-city black youth

OBJECTIVE

This investigation examined the association of violence exposure (home and neighborhood) and optimism to task-induced changes in systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse rate (PR).

METHODS

Drawn from a larger investigation, the convenience sample for this study consisted of 172 normotensive black youth (mean age = 11.5 years, standard deviation = 1.3). Violence exposure and optimism were self-reported by participants, and task-induced changes in SBP, DBP, and PR were measured with an automated monitor during two sequentially administered digit-forward and digit-backward tasks.

RESULTS

Hierarchical regression analyses revealed that violence exposure was inversely related to task-induced changes in SBP (p = .010) and DBP (p = .005). Optimism was not an independent predictor of blood pressure or PR changes (p-s > .32). The final step of these hierarchical analyses indicated that the effects of violence exposure and optimism interacted to predict task-induced changes in SBP (p = .013) and PR (p = .003). Follow-up regression analyses indicated that violence exposure was inversely related to task-induced changes in SBP among participants high in optimism and was positively associated with PR reactivity in participants low in optimism.

CONCLUSIONS

The youth in this study have intact mechanisms for buffering blood pressure responses to violence exposure, especially those who are more optimistic about their future-a person factor whose moderating effects might wane with advancing age.

Temporal stability of ambulatory stroke volume and cardiac output measured by impedance cardiography

Recently, devices have become available that allow non-invasive measurement of stroke volume and cardiac output through ambulatory thorax impedance recording. If such recordings have adequate temporal stability, they offer great potential to further our understanding of how repeated or chronic cardiovascular activation in response to naturalistic events may contribute to cardiovascular disease. In this study, 24 h ambulatory impedance-derived systolic time intervals, stroke volume and cardiac output were measured in 65 healthy subjects across an average time span of 3 years and 4 months. Stability was computed separately for sleep and daytime recordings. To avoid confounding by differences in posture and physical activity across measurement days, temporal stability was computed using sitting activities only. During the day intraclass correlations were moderate for stroke volume (.29-.46) and cardiac output (.33-.46) and good for systolic time intervals (.55-.81). When test-retest comparison was limited to two comparable days (two work days or two leisure days), correlations for both SV (.42-.46) and CO (.43-.50) improved.

CONCLUSION

Moderate long-term temporal stability is found for individual differences in ambulatory stroke volume and cardiac output measured by impedance cardiography.

Is the Advanced Trauma Life Support simulation exam more stressful for the surgeon than emergency department trauma care?

BACKGROUND

Stress affects surgeons both during training and during professional activity.

OBJECTIVE

To compare stress levels affecting surgical residents during the simulated initial assessment and management in the Advanced Trauma Life Support practical exam vs initial assessment and management of trauma patients in the emergency room.

METHOD

Eighteen surgical residents were evaluated under basal conditions, during the Advanced Trauma Life Support simulation, and during emergency room initial care. Heart rate, systolic arterial pressure, and diastolic arterial pressure were measured. The Student t test was used to test for differences between means, with statistical significance declared when P < .05.

RESULTS

Heart rate and systolic arterial pressure were increased at the beginning and at the end of Advanced Trauma Life Support simulation and emergency room initial care. Diastolic arterial pressure was only increased at the end of the Advanced Trauma Life Support simulation. Comparing values obtained during the Advanced Trauma Life Support simulation with those obtained during emergency room initial care, heart rate and systolic arterial pressure were significantly higher during the Advanced Trauma Life Support simulation both at the beginning and end of the test events. However, diastolic arterial pressure was only significantly higher for Advanced Trauma Life Support simulation compared emergency room at the end of the procedures. These results suggest that the simulation in the practical exam portion of the Advanced Trauma Life Support course is more stressful for the resident surgeon than is the actual initial assessment and care of trauma patients in an emergency room.

Program running versus problem solving: Mental task effect on tonic heart rate

It was hypothesized that mental tasks that involve program running (RUN tasks) would cause a greater tonic heart rate (HR) increase than tasks that require the search for problem solutions (EDIT tasks). Three experiments using verbal, numeric, and graphic material were run to compare tasks matched for difficulty but differing in qualitative demands (RUN vs. EDIT tasks). As predicted, filling in missing letters in words caused a larger HR increase than finding words that were logical continuations of a series of words (Experiment 1) and performing arithmetic operations caused a greater HR increase than logical completion of a series of digits (Experiment 2). In Experiment 3, two of three tasks that demanded counting of graphic elements caused a larger HR increase than a task that required logical completion of a series of graphic elements. Experiments 1 and 2 also showed that RUN tasks evoked greater phasic HR acceleration than EDIT tasks.

Cardiovascular reactivity during public speaking as a function of personality variables

An experiment was conducted to assess the effects of a real-life stressor (public speaking) upon cardiovascular reactivity (CVR). Changes in blood pressure and heart rate from baseline to task were measured in a sample of 86 men and women. The purpose was to examine the effects of individual differences (Type A personality, hostility and gender) on CVR. Participants gave a 6-min oral presentation during which they were evaluated by their professor and with classmates as the audience. Results indicated that all participants had marked CVR during public speaking. There were differences in reactivity patterns between men and women, but personality did not play a role except for high hostile men. It is suggested that intense stressors may result in high levels of CVR independent of personality variables that moderate reactivity at lower levels of stress.

Hemodynamic responses during psychological stress: Implications for studying disease processes

Investigation of the physiological correlates of psychological stress is of interest in relation to the putative impact of stress in the etiology of cardiovascular disease. Although the assessment of blood pressure and heart rate responses to psychological stress has been very informative, the addition of cardiac output measurement has added a further dimension to this research field. In recent studies, a more complete hemodynamic picture of the stress response has been documented in terms of cardiac output and systemic vascular resistance components of blood pressure changes. Different stressors have been shown to produce similar blood pressure increases due to quite different hemodynamic mechanisms. Furthermore, when faced with the same stressor, different individuals may exhibit pressor responses that are very different hemodynamically. There is growing evidence that these hemodynamic response patterns to psychological stress are stable individual traits. Response stability is a prerequisite for considering how stress-related hemodynamic changes may be implicated in the pathophysiology of cardiovascular diseases. Observations that hemodynamic response patterns in individuals at higher risk for the development of hypertension differ from those of lower risk individuals show that specific patterns of hemodynamic response are associated with disease processes. Although it is as yet unclear whether they represent markers or mechanisms. Overall. hemodynamic studies appear to he helping to refine our understanding of how stress can impact cardiovascular disease processes.

Physiological determinants of hyperreactivity to stress in borderline hypertension

Blood pressure hyperreactivity during stress is characteristic of borderline hypertension in white men. The present study evaluated the hemodynamic basis of this hyperreactivity and assessed its physiological basis in terms of sympathetic nervous system function. Cardiovascular adjustments to an aversive reaction time test were compared with those of the forehead cold pressor test, representing stressors that elicit active behavioral responses in contrast to passive tolerance of aversive stimulation. As anticipated, blood pressure increases were greater in 12 borderline hypertensive men compared with 21 age-matched normotensive men during the active reaction time stressor but not during the passive cold pressor test. The pressor hyperreactivity in borderline hypertensives was associated with excessive rises in plasma epinephrine and norepinephrine, leading to greater increases in cardiac output, despite evidence that the cardiac beta-adrenergic receptors in these subjects were downregulated compared with those of normotensive subjects. During the cold pressor test, borderline hypertension was associated with greater increases in systemic vascular resistance, which, in the presence of normal baroreceptor reflex function, led to an attenuation of cardiac output, thus producing no greater net effect on blood pressure than seen in normotensive subjects. Evidence of vascular hypertrophy in the borderline hypertensive subjects was considered to account for their vascular hyperreactivity to cold pressor stimulation. Collectively, the observations in this study further support the view that the early stages of hypertension in white men are characterized by sympathetic nervous system hyperreactivity, but only in association with tasks that elicit active behavioral coping responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of vocalization on cardiovascular and electrodermal responses during mental arithmetic

This study assessed the contribution of vocalization to autonomic responses during mental arithmetic. Specifically this study compared the autonomic responses of subjects during aloud and silent phases of repeated mental arithmetic tasks. The results were consistent for both tasks. As expected, heart rate and skin conductance responses were elevated during the aloud phases. Preejection period and cardiac output reactions, however, were greater during the silent phases. Furthermore, stroke volume declined during the aloud phases, but was maintained near resting levels during the silent phases. There were no phase effects for systolic pressure, diastolic pressure, or total peripheral resistance. The pattern of autonomic responses between aloud and silent phases of mental arithmetic suggest that the relationship between vocalization and autonomic response is not unidirectional but varies depending on the physiological parameter under investigation.