Nicotine and acute stress: effects of nicotine versus nicotine withdrawal on stress-induced hemoconcentration and cardiovascular reactivity

This study was designed to assess the effects of nicotine and nicotine withdrawal on stress-induced hemoconcentration and cardiovascular reactivity during acute stress in smokers. Forty-six smokers (>or=10 cigarettes per day) were tested twice, once while wearing a 21 mg nicotine patch for 12h and once while wearing a placebo patch (nicotine withdrawal). Calculated plasma volume, hemoglobin, hematocrit, HR, SBP, DBP, cardiac output, stroke volume, and total peripheral resistance were assessed during a 10-min baseline period, 6-min Paced Auditory Serial-Addition Task (PASAT), and a 2-min cold pressor (CP). No differences between conditions were found for any of the hematological measurements. Participants demonstrated greater HR and SBP increases to the PASAT during the nicotine withdrawal condition. For CP, participants showed greater HR and DBP increases and SV decreases during the nicotine withdrawal condition. Data from affective state ratings indicated that participants reported more negative affect during the psychological challenges during nicotine withdrawal conditions. Negative affective state may further lead to enhanced cardiovascular reactivity. These results demonstrate that although nicotine and nicotine withdrawal significantly have differential effects on cardiovascular functioning, the same differential condition effects do not appear to exist for stress-induced hemoconcentration.     

Cellular and mucosal immune reactions to mental and cold stress: associations with gender and cardiovascular reactivity

To examine gender differences in immune reactions to stress and relationships between immune and cardiovascular reactivity, measures of cellular and mucosal immunity and cardiovascular activity were recorded in 77 men and 78 women at rest and in response to active (mental arithmetic) and passive (cold pressor) stress tasks. Both tasks reduced CD4+ T cells and the CD4/8 ratio. Total lymphocytes, NK cells, CD8+ T cells, and secretory immunoglobulin A (sIgA) increased with active stress. Passive stress decreased sIgA. At rest, men had more NK cells, less CD4+ T cells, and fewer neutrophils than women. Mental stress increased sIgA in men but not women. Cardiovascular reactivity to active stress was associated with increases in NK cells. The data support the hypothesis that stress-related increases in lymphocytes are beta-adrenergically mediated, and suggest that the fall in CD4+ T cells may be alpha-adrenergically driven. Mechanisms underlying sIgA reactions are more difficult to determine. Men and women differed in some cell counts, but not in reactivity, although gender influenced sIgA reactions to arithmetic.     

Effect of meal content on heart rate variability and cardiovascular reactivity to mental stress

Little is known about transient effects of foods and nutrients on reactivity to mental stress. In a randomized crossover study of healthy adults (n=20), we measured heart rate variability (respiratory sinus arrhythmia), blood pressure, and other hemodynamic variables after three test meals varying in type and amount of fat. Measurements were collected at rest and during speech and cold pressor tasks. There were significant postmeal changes in resting diastolic blood pressure (-4%), cardiac output (+18%), total peripheral resistance (-17%), and interleukin-6 (-27%). Heart rate variability and hemodynamic reactivity to stress was not affected by meal content. We recommend that future studies control for time since last meal and continue to examine effects of meal content on heart rate variability.     

Reliability of cardiovascular reactivity to stress: internal consistency

Research on the reliability of cardiovascular reactivity has focused on temporal stability and intertask consistency with only modest results. The present study evaluated the internal consistency reliability of cardiovascular reactivity in three large samples of adolescents and young adults (N=326, 136, and 142). Impedance cardiographic and blood pressure measures were recorded at rest and during standard laboratory stress tasks (math, video game, cold pressor). The reliability of cardiovascular reactivity within tasks, as assessed by Cronbach's alpha coefficient of internal consistency, ranged from alpha=.83 to .96 for 4-min to 5-min math tasks, and alpha=.65 to .94 for 3-min video game and cold pressor tasks. Although highly reliable within tasks, cardiovascular reactivity was less reliable across tasks, even within a single testing session. Possible reasons for the discrepancy between internal consistency and intertask consistency are discussed.     

Neuroendocrine and cardiovascular reactivity to stress in mid-aged and older women: long-term temporal consistency of individual differences

We report long-term temporal consistency of stress-related neuroendocrine and cardiovascular variables in mid-aged and older women who performed mental math and speech stress tasks two times approximately 1 year apart. Epinephrine, norepinephrine, ACTH, cortisol, cardiac preejection period (PEP), respiratory sinus arrhythmia, heart rate (HR), blood pressure, and respiration rate were measured at baseline, after or during stressors, and 30 min posttask. Although there were exceptions, year-to-year Spearman coefficients showed mostly moderate to high consistency (rs approximately equal to .5-.8) for baseline, stressor, and posttask values. For reactivity, HR and PEP were most consistent (rs approximately equal to .65); consistency for other variables was moderate to low (rs approximately equal to .1-.4). Means of most variables changed from year to year. Results support the use of baseline, stressor, and posttask values in longitudinal studies.     

Abdominal obesity and chronic stress interact to predict blunted cardiovascular reactivity

Abdominal obesity and chronic stress have independent effects on cardiac autonomic regulation, and may also interact to influence cardiovascular reactivity. In addition to main effects, we hypothesized that abdominal obesity and chronic stress would interact and predict blunted cardiovascular reactivity. One hundred and twenty-two undergraduate students engaged in two stressful laboratory tasks while cardiovascular activity was assessed. Results indicated that higher abdominal obesity significantly predicted blunted systolic blood pressure (SBP) and mean arterial pressure (MAP) change, while chronic stress was not directly associated with any measure of cardiovascular reactivity. Furthermore, there was a significant interaction between abdominal obesity and chronic stress on SBP and MAP change such that among participants with higher chronic stress, higher abdominal obesity was significantly associated with reduced SBP and MAP reactivity. In addition, body-mass index (BMI), a measure of overall obesity, also had both main and interaction effects with chronic stress to predict blunted cardiovascular reactivity. These results suggest that abdominally obese individuals may incur difficulty in mounting appropriately-sized cardiovascular responses during acute stress, particularly when under high levels of chronic stress.     

Brief Reports: Further evidence for an association between self‐reported health and cardiovascular as well as cortisol reactions to acute psychological stress

In a recent study, the association between cardiovascular reactions to acute psychological stress and self‐reported health was examined. Participants with excellent or good self‐reported health exhibited higher cardiovascular reactivity than those who reported fair or poor health. We investigated this association in a population‐based cohort of whom 725 men and women, aged 55–60 years, participated in a standardized psychological stress test. We measured continuous blood pressure and heart rate as well as cortisol reactivity. Good subjective health was associated with higher cardiovascular and cortisol reactions to psychological stress. Results of the present study confirm those of the previously reported study showing that greater cardiovascular reactivity may not always be associated with negative health outcomes. In addition, the same holds for cortisol reactivity.     

Increased blood pressure reactions to acute mental stress are associated with 16‐year cardiovascular disease mortality

Exaggerated cardiovascular reactions to acute psychological stress may be involved in the etiology of cardiovascular pathology. The present analysis examined the association between the magnitude of systolic and diastolic blood pressure reactions to stress and cardiovascular disease mortality. Participants were 431 (229 women) from the West of Scotland Twenty‐07 Study, aged 63 years at the time of stress testing, where blood pressure was measured during resting baseline and mental arithmetic stress. Participants' vital status was tracked for the next 16 years, during which time 38 had died of cardiovascular disease. Both systolic and diastolic blood pressure reactions were positively associated with cardiovascular disease mortality. This association could reflect the long‐term erosive effects of exaggerated reactivity on the vasculature as well as its short‐term capacity to trigger acute cardiovascular events.     

Gender and stress: Differential psychophysiological reactivity to stress reexposure in the laboratory

Research has shown that women are more prone to the development of depression and anxiety disorders throughout their lifetimes. Stress reactivity and adaptation to repeated stressors have been linked to depression and anxiety, but studies examining gender differences in psychophysiological responses to repeated stressors are very limited. This study examined gender differences in response to initial and repeated exposure to a laboratory stressor as well as potential mechanisms for these differences. Participants viewed a Holocaust video on two occasions with a 2-day interval between sessions. Self reported negative affect and cardiovascular reactivity were recorded at both sessions. Although gender differences were not found following initial exposure, women exhibited significantly greater heart rate (HR) and negative affect (NA) reactivity to the second exposure as compared to men. Women also reported significantly greater intrusive thoughts and avoidance after the first exposure than men, but these were not found to be significant mediators. The findings indicate that women may be more vulnerable to repeated stress exposures compared to men suggesting sensitization. The implications of our findings and suggestions for future research are discussed.     

Type D personality is associated with low cardiovascular reactivity to acute mental stress in heart failure patients

Background

The distressed (Type D) personality is associated with adverse coronary heart disease outcomes, but the mechanisms accounting for this association remain to be elucidated. We examined whether myocardial and hemodynamic responses to mental stress are disrupted in Type D patients with chronic heart failure (HF).

Methods

Ninety-nine HF patients (mean age 65 ± 12 years; 75% men) underwent a public speech task, during which heart rate (HR) and blood pressure (BP) were recorded. Type D personality and its components negative affectivity (NA) and social inhibition (SI) were assessed with the DS14. General linear models with repeated measures and logistic regression were used to assess differences in stress response and recovery.

Results

Type D personality was associated with a reduced HR response (F_1,93 = 4.31, p < .05) independent of the use of beta adrenergic blocking agents and the presence of atrial fibrillation. There were no differences between HF patients with and without a Type D personality with respect to the BP response. Examining continuous NA and SI scores and their interaction (NA ∗ SI), revealed a significant association of NA ∗ SI with the SBP response (F_1,93 = 4.11, p < .05), independent of BP covariates. Results with respect to HR and DBP responses were comparable to the findings using the dichotomous Type D measure. No significant associations between Type D and recovery patterns were found.

Conclusion

HF patients with Type D personality may show an inadequate response to acute social stress, characterized by a blunted HR response.     

A tale of two mechanisms: A meta‐analytic approach toward understanding the autonomic basis of cardiovascular reactivity to acute psychological stress

A series of meta‐analyses was undertaken to determine the contributions of sympathetic and parasympathetic activation to cardiovascular stress reactivity. A literature search yielded 186 studies of sufficient quality that measured indices of sympathetic (n = 113) and/or parasympathetic activity (n = 73). A range of psychological stressors perturbed blood pressure and heart rate. There were comparable aggregate effects for sympathetic activation, as indexed by increased plasma epinephrine and norepinephrine, and shortened pre‐ejection period and parasympathetic deactivation, as indexed by heart rate variability measures. Effect sizes varied with stress task, sex, and age. In contrast to alpha‐adrenergic blockade, beta‐blockade attenuated cardiovascular reactivity. Cardiovascular reactivity to acute psychological stress would appear to reflect both beta‐adrenergic activation and vagal withdrawal to a largely equal extent.     

Aerobic exercise training and cardiovascular reactivity to psychological stress in sedentary young normotensive men and women

Forty-five (22 women) sedentary young (18-30 years old) nonsmoking normotensive volunteers engaged in either 6 weeks of aerobic training (AT), weight training (WT), or a no-treatment (NT) condition to determine whether AT lowers systolic (SBP) and diastolic (DBP) blood pressure, heart rate (HR), and rate-pressure product (RPP) during rest, psychological stress, and recovery periods. Estimated VO(2)max increased for the AT (32.1+/-1.1 to 38.4+/-1.0 ml.kg(-1).min(-1)). A smaller increase for the WT (30.5+/-1.1 to 33.8+/-1.0) was likely due to increased leg strength, and VO(2)max did not change for the NT (32.5+/-1.1 to 32.9+/-1.0). Heart rate and RPP levels were lower during psychological stress and recovery after training for AT relative to the WT and NT. Overall SBP was also lower in the AT relative to the NT but not the WT. In conclusion, aerobic training lowered cardiovascular activity levels during psychological stress and recovery in healthy young adults, implying a protective role against age-related increases in coronary heart disease for individuals who adopt aerobic exercise early in life and maintain the behavior across the life span.     

Heterogeneity in the social networks of young and older adults: prediction of mental health and cardiovascular reactivity during acute stress

We examined the utility of a broad framework that separated positive, negative, and ambivalent social network members. One hundred thirty-three young and older participants completed the social relationships index, measures of mental health, and a cardiovascular reactivity protocol. Results replicated prior research on the beneficial influence of positive (supportive) ties on psychological outcomes. More important, analyses also revealed that the number of ambivalent network ties predicted age-related differences in depression and sympathetic control of heart rate reactivity during stress. The statistical interactions between age and ambivalent ties on cardiovascular responses during stress were not changed when statistically controlling for other social network categories, demographic variables, and various personality factors. These data suggest that social network ambivalence was a relatively unique predictor of cardiovascular reactivity and highlight the utility of separating the variance due to positive, negative, and ambivalent network ties. Implications for the study of social relationships, physiological processes, and health outcomes are also discussed.     

The circadian variation of cardiovascular stress levels and reactivity: Relationships to individual differences in morningness/eveningness

Two studies assessed the circadian variation of cardiovascular responses to stress in healthy and coronary artery disease (CAD) populations. In within-subjects designs, stressors were administered to healthy male subjects and male CAD patients both in the morning and afternoon, and subjects were classified as either morning or evening types using the Morningness-Eveningness Questionnaire (Horne & Östberg, 1976, International Journal of Chronobiology, 4, 97–110). No consistent circadian variation in blood pressure or heart rate responses was observed in the aggregate sample of either healthy subjects or CAD patients. However, there were significant interactions between circadian type and time of day. In both populations, morning, subjects exhibited higher cardiovascular levels during the morning session, and evening subjects exhibited higher levels during the afternoon session. Analyses of cardiovascular reactivity revealed less consistent evidence for this interaction. Self-reports of stress revealed interactions between time of day and and morningness/eveningness only in CAD sample. In CAD patients, preliminary analysis of myocardial wall function, an index of myocardial ischemia, did not reveal a significant interaction between morningness/eveningness and time of day, perhaps due to small sample size. The presence of differing circadian patterns in stress response based on individual differences in morningness/eveningness is discussed in teerms of its methodological implications for psychophysiological research and in terms of the role of stress as an acute trigger of CAD.     

Gender differences in cardiovascular and natural killer cell reactivity to acute stress following a hassling task

To determine the influence of increased ambient stress load on subsequent cardiovascular and natural killer (NK) cell reactivity to acute stress, 30 men and women were exposed to a 5-min mental arithmetic (MA) stressor. Half the participants experienced a bureaucratic hassle designed to increase ambient stress load prior to the MA task, and the other half experienced the MA task without this pretreatment. Hassle group x gender effects suggested that hassled men had greater heart rate increases to the MA task than did hassled women, and hassled men had greater NK reactivity to the MA task than did any other group.     

Correspondence between laboratory and ambulatory measures of cardiovascular reactivity: a multilevel modeling approach

We examined the correspondence between laboratory measures of cardiovascular reactivity (CVR) and within-person changes in cardiovascular activity during the challenges of daily life, after adjustment for posture, activity, and other effects. Healthy adults (n = 335) were administered laboratory measures of CVR along with 6 days of ambulatory blood pressure monitoring and electronic diary reports. Compared with low reactors, high laboratory systolic blood pressure (SBP) reactors showed larger increases in SBP during periods of high task demand or low decisional control in daily life. High diastolic blood pressure (DBP) reactors showed larger increases in ambulatory DBP during situations rated as both low control and high demand. This multilevel modeling approach may enhance our ability to detect the correspondence between laboratory and ambulatory measures of CVR, and to identify the circumstances under which it may be most clearly observed.     

Cardiovascular reactivity and adaptation to recurrent psychological stress: replication and extension

We analyzed the effects of evaluative observation and baseline duration on cardiovascular reactivity and adaptation to recurrent psychological stress. Cardiovascular reactivity to mental arithmetic stress was assessed in college men and women (N=224) during two pretest tasks, a test task, and a posttest task. Participants were assigned randomly in a 2 x 2 design to manipulations of baseline duration before the test task (4 min vs. 12 min) and evaluative observation during the test task (observed vs. control). Repeated exposure to stress attenuated cardiac but not vascular reactivity. Evaluative observation disrupted cardiac adaptation, resulting in a resurgence of beta-adrenergic cardiac reactivity during the test task. Cardiac adaptation resumed fully during the posttest task. Baseline duration had no effect on reactivity. The results replicate and extend previous work, and support the dual process theory of habituation and sensitization.     

Zinc and copper supplementation in acute diarrhea in children: a double-blind randomized controlled trial

Background  

Diarrhea causes an estimated 2.5 million child deaths in developing countries each year, 35% of which are due to acute diarrhea. Zinc and copper stores in the body are known to be depleted during acute diarrhea. Our objectives were to evaluate the efficacy of zinc and copper supplementation when given with standard treatment to children with acute watery or bloody diarrhea.     

The effect of dietary soy supplementation compared to estrogen and placebo on menopausal symptoms: A randomized controlled trial

Objectives

To compare the effects of daily ingestion of dietary soy supplementation, low-dose hormone therapy (HT) and placebo on psychological, somatic and urogenital symptoms in postmenopausal women.

Study design

A double-blind, randomized, controlled trial. Sixty healthy, symptomatic, postmenopausal women of 40–60 years of age were allocated to use dietary soy supplementation (containing 90 mg of isoflavone) or HT (1 mg estradiol and 0.5 mg norethisterone acetate) or placebo. Main outcome measures: the Menopause Rating Scale (MRS) was used to assess menopausal symptoms at baseline and after 16 weeks of treatment. Intention-to-treat analyses were performed using the chi-square test, Fisher's exact test, the Kruskal–Wallis non-parametric test and analysis of variance (ANOVA).

Results

No statistically significant differences were found between the groups with respect to baseline clinical and sociodemographic characteristics. The psychological, somatic and urogenital symptoms analyzed in the MRS improved during treatment in all the groups, except for urogenital symptoms in the placebo group in which no significant changes were detected. Comparison between groups revealed a statistically significant improvement in somatic symptoms (hot flashes and muscle pain) in the users of HT (−45.6%) and dietary soy supplementation (−49.8%). Urogenital symptoms (vaginal dryness) improved significantly in HT users (−38.6%) and in users of the dietary soy supplementation (−31.2%). There was no statistically significant difference between the groups with respect to overall MRS score or to scores obtained in the psychological symptoms subscale.

Conclusion

Dietary soy supplementation may constitute an effective alternative therapy for somatic and urogenital symptoms of the menopause.