Menstrual cycle, race and task effects on blood pressure recovery from acute stress

Serum brain-derived neurotrophic factor predicting reduction in pulse pressure after a one-hour rest in nurses working night shifts

Night shift work is associated with cardiovascular disease and central nervous system disorders in female nurses. Brain-derived neurotrophic factor (BDNF) exerts protective effects on neural and endothelial functions. This study examined the association between serum BDNF levels and pulse pressure after rest in female nurses working night shifts. In this study, blood samples were collected for BDNF measurement after a night shift when nurses had been working night shifts for three continuous weeks. Blood pressure was assessed before and after a one-hour morning rest within a week of resuming the night shift after one month without any night shift work. The pulse pressure of nurses (n = 48, age 29 ± 5 years) was significantly reduced (from 43 ± 7 to 41 ± 6 mmHg, P = 0.003) after rest, and serum BDNF were significantly and inversely correlated with pulse pressure changes (r = −0.435, P = 0.002). Higher serum BDNF was an independent factor for greater reduction in pulse pressure (95%CI = −0.609 ‒ −0.174, P = 0.001). Using a receiver operating characteristic curve analysis, serum BDNF >20.6 ng/mL predicted a pulse pressure reduction after a one-hour rest (sensitivity 66.7%, specificity 77.8%). In conclusion, higher serum BDNF predicted greater recovery of pulse pressure after a one-hour rest in female nurses after night shift work.

Susceptibility to nausea and motion sickness as a function of the menstrual cycle

PURPOSE

The present study examined whether susceptibility to nausea and other symptoms of vection-induced motion sickness vary as a function of phase of the menstrual cycle, as research findings in this area are sparse and contradictory.

DESIGN

Ninety young women (42 current users of oral contraceptives) were exposed to a rotating optokinetic drum during the peri-menses or peri-ovulatory phase of the menstrual cycle in an independent-groups, quasi-experimental design. Nausea and motion sickness symptoms were assessed using the Nausea Profile (NP) and the Subjective Symptoms of Motion Sickness (SSMS) questionnaire.

RESULTS

Among women not on oral contraceptives, reports of nausea and motion sickness by women in the peri-menses phase were more severe than reports by women in the peri-ovulatory phase. By contrast, among women taking oral contraceptives, reports of nausea and motion sickness did not differ by the same categorical phase of the menstrual cycle.

CONCLUSIONS

We speculate that fluctuating estrogen levels over the course of the menstrual cycle may influence the experience of or susceptibility to nausea and motion sickness during illusory self-motion and other nauseogenic contexts.

Blood pressure reactivity to stress is better for people who recently had penile–vaginal intercourse than for people who had other or no sexual activity

Penile-vaginal intercourse (PVI) but not other sexual behavior is associated with better psychological and physiological function. I examined the relationship of sexual behavior patterns to blood pressure (BP) and its reactivity to stress (public speaking and verbal arithmetic). For a fortnight, 24 women and 22 men used daily diaries to record PVI, masturbation, and partnered sexual behavior in the absence of PVI. Persons who reported PVI (but no other sexual activities) had better stress response (less reactivity and/or lower baseline levels) than persons reporting other or no sexual behaviors. Persons who only masturbated or had partnered sex without PVI had 14 mmHg more systolic BP reactivity than those who had PVI but not the other behaviors. Many variables were examined but failed to confound the observed relationships. The magnitude of the sexual behavior effect on BP reactivity is greater than of other factors in the literature. These findings add to the research corpus on the benefits of PVI (differentiated from other sexual activities).

Breast feeding, bottle feeding, and maternal autonomic responses to stress

OBJECTIVE

The aim of this study was to examine the effects of breast feeding on autonomic nervous system (ANS) response to stressors.

METHODS

Sympathetic and parasympathetic activities were examined before, during, and after standard laboratory stressors in women who were either exclusively breast feeding (n=14) or nonexclusively breast feeding (n=14), and in non-postpartum controls (n=15).

RESULTS

Mothers who breast fed exclusively showed greater levels of parasympathetic cardiac modulation and slower heart rate (HR) throughout the session and less HR increase and preejection period (PEP) shortening to mental arithmetic (MA) than did nonexclusive breast feeders and controls. Nonexclusive breast-feeders showed greater electrodermal reactivity to, and greater differences in skin conductance response (SCR) frequency between baseline and recovery from cold pressor (CP) than did either exclusive breast-feeders or controls. Sympathetic activity was negatively related to the number of breast feedings and positively related to bottle feedings.

CONCLUSION

Breast feeding shifts maternal ANS balance toward relatively greater parasympathetic and lesser sympathetic activity; the opposite occurs with bottle feeding. The frequency of feeding also is a critical factor in determining breast feeding effects on maternal ANS function.

Cardiovascular reactivity to mental arithmetic and cold pressorin African Americans, Caribbean Americans, and white Americans

BACKGROUND

Caribbean Americans and African Americans, two of the largest Black ethnic groups in the United States, differ in cardiovascular-disease-related mortality rates.

PURPOSE

Cardiovascular reactivity to psychological stress may be an important marker or mediator of risk for cardiovascular disease development in Blacks in the United States, yet little attention has been paid to ethnicity among Blacks in reactivity research. This study examined cardiovascular reactivity to psychological stress in African American, Caribbean American, and White American participants.

METHODS

Forty-five women and 43 men performed mental arithmetic and hand cold pressor (CP) tasks.

RESULTS

Caribbean Americans displayed larger decreases in heart period variability during mental arithmetic than White Americans (p =.02). White Americans exhibited a pre-ejection period decrease, whereas African Americans and Caribbean Americans displayed pre-ejection period increases during CP (p =.023). African Americans exhibited greater decreases in interbeat interval during CP than White Americans (p =.013). Caribbean Americans displayed greater decreases in cardiac output than White Americans during CP (p =.009). White Americans exhibited significantly greater increases in systolic blood pressure than Caribbean Americans during CP (p =.014).

CONCLUSIONS

These findings suggest that differences in reactivity to psychological stress exist among Black ethnic groups in the United States and underscore the need to consider ethnicity as a factor in reactivity research with Black Americans.

Applying latent growth curve modeling to the investigation of individual differences in cardiovascular recovery from stress

OBJECTIVE

This paper provides an introduction to latent growth curve (LGC) modeling, a modern method for analyzing data resulting from change processes such as cardiovascular recovery from stress. LGC models are superior to traditional approaches such as repeated measures analysis of variance and simple change scores.

METHODS

The basic principles of LGC modeling are introduced and applied to data from 167 men and women whose systolic blood pressure was assessed before, during, and after the cold pressor and evaluated speech stressors and who had completed the Cook-Medley Hostility Inventory.

RESULTS

The LGC models revealed that systolic blood pressure recovery follows a different nonlinear trajectory after speech relative to the cold pressor. The difference resulted not from the initial decline at the completion of the stressor, but from higher levels at the end of the stressor and slower rate of change in decline for the speech. Hostility predicted the trajectory for speech but not for cold pressor. This relationship did not differ as a function of gender, although men had larger systolic blood pressure responses than women to both stressors.

CONCLUSIONS

LGC modeling yields an understanding of the processes and predictors of change that is not attainable through traditional statistical methods. Although our application concerns cardiovascular recovery from stress, LGC modeling has many other potential applications in psychosomatic research.

Perceived racism and blood pressure: a review of the literature and conceptual and methodological critique

Racial disparities in health, including elevated rates of hypertension (HT) among Blacks, are widely recognized and a matter of serious concern. Researchers have hypothesized that social stress, and in particular exposure to racism, may account for some of the between-group differences in the prevalence of HT and a portion of the within-group variations in risk for HT. However, there have been surprisingly few empirical studies of the relationship between perceived racism and blood pressure (BP) or cardiovascular reactivity (CVR), a possible marker of mechanisms culminating in cardiovascular disease. This article reviews published literature investigating the relationship of perceived racism to HT-related variables, including self-reported history of HT, BP level, or CVR. Strengths and weaknesses of the existing research are discussed to permit the identification of research areas that may elucidate the biopsychosocial mechanisms potentially linking racism to HT. We hope to encourage investigators to invest in research on the health effects of racism because a sound and detailed knowledge base in this area is necessary to address racial disparities in health.

Hemodynamic responses to stress among black women: fitness and parental hypertension

PURPOSE

We compared hemodynamic aspects of the relationship between cardiorespiratory fitness and blood pressure changes during and after laboratory stress in young black women with or without parental history of hypertension.

METHODS

Participants were 30 normotensive, black American women having low to moderate fitness levels (i.e., VO2peak) assessed by cycle ergometry who performed standard active and passive coping laboratory stressors. Blood pressure, heart rate, stroke volume, cardiac output, total peripheral resistance (TPR), calf blood flow (CBF), and calf vascular resistance (CVR) were assessed during exposure to forehead and hand cold pressors, and mental arithmetic, as well as during recovery after the tasks.

RESULTS

Fitness was positively related to increases in either TPR or CVR during each stressor. In contrast, fitness was positively related to blunted blood pressure during or after passive stress (i.e., hand or forehead cold) and enhanced recovery of blood pressure and TPR after the active stressor (i.e., mental arithmetic); effects of fitness on the vascular responses during and after mental arithmetic were stronger among women having a negative history of parental hypertension.

CONCLUSION

The findings confirm our previous report that fitness blunts systolic blood pressure response during the hand cold pressor in young women. They also suggest that future studies of fitness and blood pressure reactivity during stress should focus on the regulation of vascular responses and their recovery after stress. Weaker effects of VO2peak after mental arithmetic in the positive history group indicate that the level of fitness required to modify recovery from mental stress among black American women may differ according to parental history of hypertension.

Impact of stress, gender and menstrual cycle on immune system: possible role of nitric oxide

Stress is a factor found to be involved in the etiology of many diseases. Gender and menstrual cycle phases are other factors affecting the predisposition of individuals for certain diseases. Results from animal and human studies suggest that the distribution of immune system cells may change at different phases of the menstrual cycle. Acute mental stress in humans alters immune variables, too. The increase in the number of natural killer (NK) cells is the most consistent finding among the immune variables, though there are controversies for the other lymphocyte groups. Nitric oxide (NO) as an immune mediator has an unsettled role whether it causes the redistribution of the immune cells, or is an end product of lymphocyte activation. This study was planned to investigate the effect of mental stress on lymphocyte subtypes and the role of NO, for men and women at different phases of the cycle. For this purpose, healthy men (n = 10) and women (n = 10), during the follicular and luteal phases underwent Stroop colour-word interference and cold pressor tests. The immune system responses before and after the tests were determined by cell counts with the flowcytometer. Menstrual cycle phase was ascertained by plasma estrogen and progesterone measurements. Stress response was evaluated by blood pressure (BP) and heart rate (HR) measurements throughout the tests and plasma cortisol and urinary metanephrine and vanillylmandelic acid (VMA) measurements before and after the tests. Plasma and urinary NO determinations were performed before and after the test was completed. All the results were analysed with the appropriate statistical methods. The luteal phase differed from the other groups due to the presence of suppressed immune response to acute stress, including decreased CD4/CD8 ratio and NK cell percentage. On the other hand, acute stress caused a shift from cellular to humoral immunity in men. As indicated by these results, individual reaction towards stress is affected by gender and menstrual cycle phase. NO appears to be a possible effector molecule for these differences.

Vagal rebound and recovery from psychological stress

OBJECTIVE

To characterize cardiovascular recovery and examine the possible relationship of vagal activity and reflexes to risk for heart disease.

METHODS

Subjects performed cold pressor and mental arithmetic tasks. Heart rate, heart period variability, and pre-ejection period were obtained for 1 minute before, during, and after each task (Experiment 1). In the second experiment, subjects performed a Stroop color-word task and a mental arithmetic task. Heart rate, heart period variability, blood pressure, and baroreflex sensitivity were obtained during the 5-minute baseline, task, and recovery periods (Experiment 2).

RESULTS

In Experiment 1, heart rate during recovery was lower than baseline despite continued pre-ejection period shortening, whereas recovery heart period variability was higher than baseline. In Experiment 2, blood pressure increased throughout the session. However, recovery heart rate after mental arithmetic was lower than baseline heart rate, and heart period variability was higher during both recovery periods than during baseline. Vagal rebound, a sharp increase in variability in the first minute of recovery, was reduced in men in Experiment 1 and in individuals with a family history of cardiovascular disease in Experiment 2 and was associated with degree of change in baroreflex sensitivity between task and rest.

CONCLUSIONS

Cardiovascular recovery from stress is associated with increased vagal modulation despite residual sympathetic activation. Vagal rebound may be involved in mechanisms resetting the baroreflex sensitivity at the onset and offset of stress. Diminished vagal rebound during recovery from stress is associated with standard risk factors for cardiovascular disease. The results support an association between attenuated vagal reflexes and risk for cardiovascular disease.