Stress-induced hemoconcentration of blood cells and lipids in healthy women during acute psychological stress

This study examined the effects of psychological stress on hemoconcentration in women. Hematologic and hemodynamic variables were assessed in 17 women before and after a 3-min speech task. Significant changes in hematocrit, hemoglobin levels, red and white blood cell (WBC) count, and calculated plasma volume occurred during psychological stress (all ps < .05). Significant increases were also observed for total cholesterol, triglycerides, high density lipoprotein cholesterol, low density lipoprotein cholesterol, and free fatty acid (FFA; all ps < .05) during stress. After statistically correcting for the hemoconcentration effects of decreased plasma volume during stress, only WBC count and FFA concentration remained significantly elevated during the stress task (p < .006 and p < .05, respectively). In sum, acute stress alters hemoconcentration in women, which in turn can account for most stress-induced changes in lipids.

Psychological stress and immunological responsiveness in normally cycling, follicular-stage women

Nineteen women in the follicular stage of their menstrual cycles were assessed for immunological responsiveness to a 50-min series of three psychological tasks which reliably elicit cardiovascular and neuroendocrine stress responses. Ten follicular-stage women not subjected to stress served as controls. Stress decreased lymphocyte responsiveness to PHA and PWM, percent of CD4+ cells and the ratio of CD4+/CD8+ cells. Conversely, stress increased natural killer cell number and cytolytic activity, white blood cell, lymphocyte, T and B cell count. Except for natural killer cell number, none of these changes was exhibited by controls. Most of these stress responses are similar to those reported for men and form the basis for a continuing study of the effects of reproductive hormones and stress on cardiovascular and immunological function in women.

Menopausal status influences ambulatory blood pressure levels and blood pressure changes during mental stress

BACKGROUND

Frequent and large cardiovascular and neuroendocrine responses to psychological stress are thought to enhance an individual's risk for cardiovascular diseases. Preliminary data suggest that levels of reproductive hormones affect the magnitude of stress responses, perhaps contributing to the protective effect of ovarian hormones on premenopausal women's rates of coronary heart disease.

METHODS AND RESULTS

Healthy middle-aged men and premenopausal and postmenopausal women performed a series of standardized mental and physical challenges while blood pressure, heart rate, plasma catecholamines, lipids, and lipoproteins were measured. Subjects then wore an ambulatory blood pressure monitor during two consecutive workdays. Results showed that postmenopausal women had larger mean +/- SEM stress-induced increases in systolic blood pressure (24.7 +/- 2.2 mm Hg) and diastolic blood pressure (14.3 +/- 1.0 mm Hg) compared with either premenopausal women (16.9 +/- 1.3 and 10.2 +/- 0.9 mm Hg) or men (17.7 +/- 1.5 and 10.9 +/- 1.1 mm Hg, respectively). Postmenopausal women and men had higher mean +/- SEM ambulatory diastolic blood pressure levels (75.5 +/- 3.2 and 76.4 +/- 1.8 mm Hg) than did premenopausal women (69.9 +/- 2.2 mm Hg). Large blood pressure responses during public speaking were associated with high cholesterol levels and low educational attainment.

CONCLUSIONS

Menopause is associated with enhanced stress-induced cardiovascular responses and elevated ambulatory blood pressure during the workday. These effects may contribute to the risk of cardiovascular morbidity and mortality after the menopause.

Hemodynamic adjustments to laboratory stress: the influence of gender and personality

Exaggerated cardiovascular reactivity to psychological stress is a potential pathophysiological mechanism linking behavior and cardiovascular disease. Because of the recognized gender differences in incidence of cardiovascular disease, potential gender differences in cardiovascular reactivity to laboratory stressors have been evaluated. The current study examined the cardiovascular responses of a total of 42 young women (N = 22) and men (N = 20) undergoing a laboratory protocol including the following: a nonverbal math task, a mirror tracing task, the Stroop Color-Word interference task, and an isometric handgrip task. In addition to the assessment of heart rate and blood pressure, cardiac output, stroke volume, total peripheral resistance and preejection period were assessed by impedance cardiography. A number of personality characteristics that vary in prevalence by gender were also measured to evaluate their ability to explain potential gender differences in cardiovascular responses. Results indicated that men responded with greater total peripheral resistance and systolic and diastolic blood pressure responses than did women on a subset of tasks, whereas women exhibited larger increases in heart rate on a subset of tasks. Thus, men were more likely to be "vascular" reactors, with women being more likely to be "cardiac" reactors. Personality characteristics did differ between men and women, but did not explain significant variance in the gender differences in cardiovascular responses. We conclude that additional studies should focus on experimental manipulations of potential physiological mechanisms responsible for these differences, such as reproductive hormones.

Do cardiovascular responses to laboratory stress relate to ambulatory blood pressure levels?: Yes, in some of the people, some of the time

Because the correspondence between laboratory measures of blood pressure and heart rate responses to stress and ambulatory measures is less than optimal, this study tested two hypotheses: Are ambulatory measures of blood pressure elevated during periods of perceived stress, relative to no stress? Are ambulatory blood pressures elevated during perceived stress among those individuals who exhibit elevated blood pressure and heart rate responses to laboratory stress? These questions were addressed in a sample of employed, middle-aged men and premenopausal and postmenopausal women, who vary in reproductive hormone status, and in risk for coronary heart disease. All participants performed a series of laboratory studies while their physiological parameters were monitored and then wore an ambulatory blood pressure monitor for a day and a half. This monitor recorded blood pressure every half hour during the waking hours and at the same time the participants assessed their mood states. After excluding participants who reported no variability in stress levels, those who were cardiovascular reactors to a laboratory speech task exhibited elevated ambulatory blood pressure levels during periods of perceived stress. Furthermore, in general, periods of perceived stress were associated on a within subject basis with elevated ambulatory blood pressure. These results suggest that the correspondence between laboratory and field measures of blood pressure would be improved by taking into account the environmental circumstances during the ambulatory assessments and the person characteristics of reactor-nonreactor to laboratory stress.

Can physical activity mitigate the effects of aging in middle-aged women?

BACKGROUND

Aging is associated with an increased risk of women dying from coronary heart disease as well as from all causes combined. Alterations in the major biological risk factors for early coronary heart disease and all-cause mortality are frequently seen in aging.

METHODS AND RESULTS

The present investigation tested the hypothesis that high levels of physical activity could protect against age-associated changes in biological risk factor levels. In the Healthy Women Study, 507 women were evaluated at study entry and 3 years later. Weekly physical activity level was measured at each examination via the Paffenbarger Physical Activity Questionnaire. During the 3-year period, women increased significantly in weight, blood pressure, levels of total and low-density lipoprotein cholesterol, triglycerides, and insulin and decreased significantly in levels of total high-density lipoprotein cholesterol (HDL-C) and HDL2-C.

CONCLUSIONS

Consistent with the study hypothesis, women who reported higher levels of activity at baseline had less weight gain over time. Furthermore, women who increased their activity during the 3-year interval had the smallest increases in weight and tended to have the smallest decreases in total HDL-C and HDL2-C. The changes in lipids due to activity were largely independent of changes in body weight.

Does the gender relevance of the stressor influence sex differences in psychophysiological responses?

Sex differences in psychophysiological responses to stress may be important to understanding sex differences in risk for coronary heart disease. This investigation tested the hypothesis that the gender relevance of the stressor influences the extent of sex differences in cardiovascular, neuroendocrine, and lipid responses during stress. Participants performed two tasks that were described as masculine oriented, feminine oriented, or not gender relevant. Although these descriptions influenced the participants' perceptions of the tasks, they did not influence the extent of sex differences in physiological responses in a manner consistent with the study hypothesis. Future directions for research are discussed regarding sex differences in psychophysiological responses.

T-lymphocyte reactivity during the menstrual cycle in women

Reactivity of blood lymphocytes to nonspecific mitogenic stimulation with phytohemagglutinin (PHA) was measured in nine healthy, regularly cycling women at three phases of their menstrual cycles corresponding to peak levels of estradiol (midfollicular phase), peak levels of progesterone (midluteal phase), and the lowest levels of both hormones (menstrual phase). Sampling points were verified by radioimmunoassay of estrogen, progesterone, luteinizing hormone, and follicle-stimulating hormone. There were significant increases in reactivity associated with an increasing concentration of PHA and with autologous plasma vs AB plasma. However, no differences were found in reactivity to PHA over the three menstrual cycle phases and correlational analyses indicated no relationship between counts and any of the hormones measured.

Physical activity and cardiovascular risk: a cross-sectional study of middle-aged premenopausal women

The relationship between self-reported physical activity and cardiovascular risk factors was evaluated in a population-based sample. The sample included 541 premenopausal women recruited for a study of the natural history of risk factor change associated with change in sex hormone status. Physical activity was assessed using the Paffenbarger Activity Questionnaire. Women were classified according to quartile of weekly energy expenditure into groups of 0-500, 501-999, 1,000-1,999, and 2,000 kcal or greater. Results showed that the more active the women, the lower their blood pressure and heart rate. More active women had lower cholesterol and triglycerides, and higher high-density lipoprotein (HDL) cholesterol. Tricep and suprailiac skinfolds, fasting insulin, and insulin/glucose levels were also lower among the more active women. When the analysis was repeated controlling for the effect of education and body mass index, the statistical test for linear trend remained significant except for the trend for heart rate, total cholesterol, and triglycerides. Women reporting activity of 1,000 kcal/week had higher high-density lipoprotein cholesterol and lower diastolic blood pressure, body mass index, skinfolds, fasting insulin, and fasting insulin/glucose ratios compared with women reporting lower levels of activity. Only those women who reported 2,000 kcal/week had significantly lower total cholesterol, triglycerides, and low-density lipoprotein cholesterol, and higher HDL2 cholesterol; women reporting less activity did not differ with regard to these lipids and lipoproteins. The study suggests that physical activity is associated with improved cardiovascular risk profiles among middle-aged women and that the beneficial effects of activity are seen at different levels for specific risk factors.

Influences of the normal menstrual cycle on physiologic functioning during behavioral stress

The purpose of this study was to evaluate the influence of the normal menstrual cycle on lipoprotein, cardiovascular, and neuroendocrine stress responses. Fifteen normally-cycling, healthy women participated in a series of behavioral tasks during the menstrual, follicular, and luteal phases of their menstrual cycle. These women had established menstrual cycle regularity for the three months prior to enrollment in this study, were free from menstrual cycle disturbances, biochemically confirmed that they ovulated, and displayed appropriate patterns of reproductive hormone fluctuations during the study period. Heart rate, blood pressure, low density lipoprotein-cholesterol, and total cholesterol all demonstrated significant elevations from baseline levels during tasks. No differences in the magnitude of stress responses during the three menstrual cycle phases were noted for any physiological variable. We conclude that the hormonal fluctuations that occur in healthy, normally-cycling women during the menstrual cycle do not influence the stress responses that were investigated here. Significant influences of menstrual cycle phase previously reported in the literature, albeit not in a consistent direction, may have been due to the recruitment of women with menstrual cycle irregularities, and to the failure to adequately verify menstrual cycle phase.

Dispositional optimism and recovery from coronary artery bypass surgery: the beneficial effects on physical and psychological well-being

The effect of dispositional optimism on recovery from coronary artery bypass surgery was examined in a group of 51 middle-aged men. Patients provided information at three points in time--(a) on the day before surgery, (b) 6-8 days postoperatively, and (c) 6 months postoperatively. Information was obtained relating to the patient's rate of physical recovery, mood, and postsurgical quality of life. Information was also gathered regarding the manner in which the patients attempted to cope with the stress of the surgery and its aftermath. As expected, dispositional optimism proved to be an important predictor of coping efforts and of surgical outcomes. More specifically, dispositional optimism (as assessed prior to surgery) correlated positively with manifestations of problem-focused coping and negatively with the use of denial. Dispositional optimism was also associated with a faster rate of physical recovery during the period of hospitalization and with a faster rate of return to normal life activities subsequent to discharge. Finally, there was a strong positive association between level of optimism and postsurgical quality of life at 6 months.