Race, Parental History of Hypertension, and Patterns of Cardiovascular Reactivity in Women

This study examined the interaction of race and parental history of hypertension on patterns of cardiovascular responses among women. Two stressors were used that produce different patterns of cardiovascular reactivity: mental arithmetic, primarily a beta-adrenergic stimulus, and the cold face stimulus, which evokes alpha-adrenergic (i.e. vascular) activity. Systolic and diastolic blood pressure, heart rate, forearm blood flow, and forearm vascular resistance were assessed before, during, and after arithmetic and cold face stimulus. Both tasks produced the expected patterns of cardiovascular adjustment, although no Black-White differences occurred during arithmetic. However, Black subjects did show a slower recovery of diastolic blood pressure following arithmetic. The cold face stimulus produced significantly greater changes in systolic blood pressure in the Black than in the White women. Parental history of hypertension did not relate significantly to reactivity. The results provide limited support for the idea that Black females exhibit a greater pressor response than White females to a stimulus that produces primarily vascular rather than cardiac changes. These findings are discussed in relation to previous findings with males and with respect to their implications for the role of reactivity in Black-White differences in hypertension prevalence.     

Empirical contributions

To evaluate the possible negative association between risk for hypertension and pain sensitivity in women, 24 healthy young adult women with a parental history of hypertension and 24 without a parental history of hypertension participated in 2 laboratory sessions in which electric shock and the cold-pressor test were administered. To assess the possible role of stress-induced analgesia in blood pressure-related hypoalgesia, the sessions were identical with the exception of the fact that participants were exposed to a stressful 20-min videogame before the pain stimuli on one occasion and a nonstressful control task on the other. Women with a parental history of hypertension and high blood pressure reactivity to the videogame displayed a reduced sensitivity to electric shock on both days, suggesting that risk for hypertension is associated with reduced sensitivity to at least some pain stimuli in women. Blood pressure reactivity to stress-associated baroreceptor stimulation was not implicated as a mediator of decreased pain perception. However, other analyses revealed an effect of family history on shock pain only among women who reported relatively high anxiety, suggesting that other aspects of the stress response may be involved in this phenomenon. This research was supported by the Heart and Stroke Foundation of Quebec and an Academic Challenge grant from the state of Ohio     

Neuroendocrine and Cardiovascular Stress Reactivity in Middle-Aged Normotensive Adults with Parental History of Cardiovascular Disease

Neuroendocrine and cardiovascular stress reactivity was studied in healthy middle-aged individuals whose parental history included essential hypertension and/or myocardial infarction and a control group without parental history of cardiovascular disease. All subjects completed a rest session (1 hour) and a stress session (1 hour). The stress session included behavioral (mirror image tracing, mental arithmetic, and the Stroop color word conflict test) and physical stressors (the cold pressor test and isometric exercise). Systolic and diastolic blood pressures and heart rate were recorded at baseline before and during all stressors. Specimens for determination of urinary catecholamines and cortisol were sampled after the rest and stress sessions respectively. Generally, a parental history of hypertension but not of myocardial infarction influenced neuroendocrine and cardiovascular stress reactivity. A family history of hypertension was associated with exaggerated epinephrine, norepinephrine, and cortisol excretion during stress and with enhanced heart-rate reactivity to behavioral (mental arithmetic and mirror image tracing) but not to physical stressors (isometric exercise or the cold pressor test). We conclude that individuals with a family history of hypertension tend to display exaggerated cardiovascular and neuroendocrine reactivity to stress.     

Effects of menstrual phase and parental history of hypertension on cardiovascular response to cognitive challenge

The effects of parental history of hypertension and menstrual phase on systolic and diastolic blood pressure (SBP, DBP) and heart rate (HR) responses to two frustrating cognitive tasks were examined in 47 normotensive, young adult women. Subjects with and without a parental history of hypertension were scheduled to be tested during either the follicular (days 7-11 of a 28-day cycle) or luteal (days 17-22) phase of the menstrual cycle. During the laboratory session, HR, SBP, DBP, and self-report of affective states were measured while subjects performed two cognitive tasks (mental arithmetic and concept formation). Results indicated that the magnitude of SBP responses to the two tasks was significantly greater in subjects tested during the follicular phase than in subjects tested in the luteal phase of the menstrual cycle. No effect of parental hypertension was observed on cardiovascular response measures, though offspring of hypertensive parents reported experiencing significantly less anger during the tasks than subjects with normotensive parents.     

Assessment of Baroreceptor Reflex Function During Mental Stress and Relaxation

This paper describes a method of measuring baroreceptor cardiac reflex sensitivity noninvasively from spontaneous patterns of blood pressure and interbeat interval, and the application of this technique in psychophysiology. Baroreflex function was assessed in 24 female volunteers during relaxation and performance of the cold pressor test and a non-verbal mental arithmetic task. Blood pressure and interbeat interval were monitored continuously from the finger using the vascular unloading technique. Sequences of three or more cardiac cycles were identified over which systolic blood pressure increased progressively in conjunction with lengthening interbeat interval, or systolic blood pressure decreased as interbeat interval was reduced. The regression between systolic blood pressure and interbeat interval was computed as an index of baroreflex sensitivity. Relaxation was associated with a small prolongation of interbeat interval, whereas baroreflex sensitivity increased from 17.1 to 19.8 ms/mmHg. Baroreflex sensitivity was reduced significantly during mental arithmetic (mean 14.2 ms/mmHg) but not during the cold pressor test (mean 17.4 ms/mmHg). The difference between mental arithmetic and the cold pressor test may be related to the relative intensity of cardiac and vascular responses in the two situations. The implications of these results for the understanding of behavioural influences on haemodynamic function are discussed and the advantages of noninvasive methods are considered.     

Hypertension risk factors and cardiovascular reactivity to mental stress in young men

Hypertension risk may be associated with increased pressor response to mental stress. However, studies using family history as a predictor of reactivity have obtained mixed results. We assessed cardiovascular responses to mental arithmetic stress (a 5-min serial subtraction task) in male medical students (n = 220) at three levels of hypertension risk based on parental history and the subject's systolic blood pressure (SBP): low (SBP < 125 mm Hg and 0 or 1 hypertensive parent), moderate (resting SBP ≥ 125 mm Hg or 2 hypertensive parents), or high (resting SBP ≥ 125 mm Hg and 1 or 2 hypertensive parents). High risk men showed the greatest blood pressure responses ( + 22/ + 16 mm Hg), while moderate and low-risk groups showed correspondingly smaller responses ( + 17/ + 13 and + 14/ + 11 mm Hg, p's < 0.02). Family history alone did not predict differential reactivity. This study replicates and extends our previous work suggesting the importance of using both family history and resting blood pressure level in determining future risk for hypertension in studies of cardiovascular reactivity in relation to hypertension risk in males.     

Cardiovascular reactivity with caffeine and stress in black and white normotensive females

Forty-eight healthy, young, normotensive black and white women, half with and half without a parental history of hypertension, were studied using a double-blind, randomized design. Systolic (SBP) and diastolic (DBP) blood pressures and heart rate (HR) were recorded in response to 250 mg of caffeine vs placebo (3 mg) during rest and during a stressful mental arithmetic task. Results indicated no racial or parental history differences in response to caffeine or to stress. Surprisingly, our female subjects evidenced a small drop in SBP (1 mm Hg) and a decline in HR (5 bpm), and, as expected, they demonstrated a rise in DBP of 6 mm Hg in response to caffeine. The effects of caffeine on SBP and HR were contingent on the experimental condition such that the difference in SBP and HR between the high vs low dose of caffeine was significant only under the caffeine plus psychological stress condition. These effects were only partially consistent with those previously observed in males. Previous evidence of significantly greater DBP pressor effects when caffeine is consumed under stressful conditions was confirmed. However, in this study, the caffeine alone condition had little effect on SBP reactivity and promoted a decrease in HR reactivity. The results are discussed in relation to previous research on males, and recommendations for future research are offered.     

Parental History of Essential Hypertension, Active Coping, and Cardiovascular Reactivity

Differences in cardiovascular reactivity to stress between individuals with and without a family history of essential hypertension (EH) may be affected by stimulus characteristics and/or individual differences in behavioral response. Twenty-four male students with a parental history of EH and 24 without a parental history of EH participated in two laboratory sessions during which two “active’ (mental arithmetic and the Stroop word-color interference test) stressors and one “non-active’ (isometric hand-grip) stressor were presented. Family history subjects exhibited greater systolic blood pressure responses than non-family history subjects only to the two active stressors in Session 2, despite the fact that, overall, isometric hand-grip elicited the largest responses. High-performing Stroop subjects with a parental history of EH displayed greater heart rate responses to the task than high-performing subjects without a parental history of EH in both sessions. No group differences appeared among poor performers. The degree to which a stressor encourages active coping behavior appears to be one determinant of differences in cardiovascular response between individuals with and without a family history of EH.     

Caffeine, mental stress, and risk for hypertension: a cross-cultural replication

Separate and combined effects of caffeine and mental arithmetic stress on systolic blood pressure (SBP) and heart rate (HR) were assessed in a double-blind, placebo-controlled study. Thirty-six Chinese nationals, half with and half without a family history of hypertension, received either 0, 125, or 250 mg of caffeine in three separate experimental sessions, each preceded by a 12-hour abstention from caffeine consumption. Caffeine and mental stress elevated SBP, but caffeine did not potentiate the SBP response to mental stress. Caffeine did not affect HR. A positive family history of hypertension was associated with larger SBP elevations to the higher dose of caffeine. Family history of hypertension was associated with larger blood pressure elevations during mental stress, but only under conditions of high-level stimulation provided by the initial exposure to the stress. These results support previous findings of greater cardiovascular reactivity to laboratory stress in individuals at high risk for hypertension.     

Effects of parental history of hypertension and urbanization on blood pressure in zimbabweans

The increasing prevalence of essential hypertension is a growing public health concern for Zimbabwe and other African countries. Two important risk factors for hypertension are urbanization and parental history of hypertension. The relations among parental history of hypertension, urbanization, and blood pressures (BPs) are poorly understood. The objective of this study is to clarify these relations in a population of urbanized. African, young adults. The relation between parental history of hypertension and urbanization on resting BPs and BP responses to a menial arithmetic stressor was examined in a group of normotensive, Black medical students with (n = 36) and without (n = 34) a parental history of high BP.and with (n = 49) and without (n = 19) a parental history of urbanization. Results indicate that those with a positive parental history of high BP had higher resting BPs and greater systolic blood pressure (SBP) increases in response to laboratory stress, when compared to their negative parental history counterparts. Further, those with parents residing in urban areas had higher resting SBPs than those with parents residing in rural areas. However, no reactivity differences were apparent between the urban and rural parent groups. These data suggest that although parental history for hypertension influences both resting and reactivity BPs, parental history of urbanization may influence only resting BP. This study was supported by NIH/Fogarty International Center Grants 5T37TW3041-02, N1H-HL35195. and NIH-HL32738.     

Family history of hypertension and vasovagal symptoms during blood donation

Vasovagal reactions during blood donation were assessed in 185 individuals with and 298 individuals without a parental history of hypertension. It was predicted that individuals at genetic risk for hypertension would be less likely to faint or suffer pronounced vasovagal reactions, presumably by virtue of altered baroreflex sensitivity. A relationship between a parental history of hypertension and vasovagal responses was observed, albeit modified by blood donation experience and sex. Nurses obtaining blood from inexperienced donors without a parental history of hypertension were significantly more likely to recline the subject's chair than those obtaining blood from inexperienced donors with a parental history of hypertension or experienced donors. Questionnaire data were consistent with these findings. These results may be an interesting reflection of group differences in baroreflex sensitivity and have implications for screening potential donors.     

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.     

Baroreceptor sensitivity and effectiveness varies differentially as a function of cognitive-attentional demands

From the spontaneous sequence method, a new index of baroreceptor function has recently been proposed, the baroreflex effectiveness index (BEI). BEI quantifies the number of times the baroreflex is effective in driving the sinus node. In this study we examined how different cognitive-attentional demands modulates BEI and baroreceptor reflex sensitivity (BRS). Eighty three students performed three tasks: mental arithmetic, memory, and visual attention. Results indicate that BRS reliably decreases during mental arithmetic and increases slightly during visual attention. BEI increases during the visual attention task. The overall pressure change of the systolic blood pressure ramps decreases during tasks with respect to baseline periods and cannot explain the effect found in BEI (in effect, BEI works against this underlining influence). The modulation found in BRS and BEI as a function of cognitive demand is in accordance with the Laceys' intake/rejection theory. Specifically, it is suggested that BRS is more sensitive to internal cognitive elaboration conditions, while BEI is more sensitive to external attention conditions.     

Exaggerated Sympathetic Nervous System Response to Extended Psychological Stress in Offspring of Hypertensives

The cardiovascular responses of 24 healthy young adult males with a parental history of hypertension and 24 males without a parental history of hypertension to an extended active-coping psychological stressor were compared under three drug conditions: placebo, the beta 1-blocking agent metoprolol, and the alpha 1-blocking agent prazosin. In the placebo condition, offspring of hypertensives exhibited significantly greater heart rate, blood volume pulse, and forearm blood flow responses to the task. They also exhibited a significantly greater initial decrease in forearm vascular resistance, which, in contrast to the offspring of normotensives, was no longer significantly different from baseline levels by the end of the session. No group differences in blood pressure response were observed. Metoprolol eliminated the differences in heart rate and forearm vascular resistance responses. Prazosin eliminated the difference in blood volume pulse response and elicited a sustained group difference in forearm vascular resistance. These results implicate the sympathetic nervous system in the exaggerated cardiovascular responsivity to psychological stress in individuals with a family history of essential hypertension. They also suggest that the pattern of increasing vascular resistance in response to this stressor observed in this and other studies in this laboratory reflects alpha-adrenergic activity and not neurohumorally independent autoregulation.     

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.     

Racial differences in cardiovascular reactivity to mental arithmetic

One hypothesized mechanism for the higher rates and greater severity of essential hypertension among blacks is that this group is particularly susceptible to stress-induced beta-adrenergically mediated cardiovascular hyperreactivity. In this study, we compared the cardiovascular responses to mental arithmetic in 20 white and 17 black, young, normotensive males. Contrary to expectations, the black subjects exhibited significantly smaller changes in heart rate, and systolic and diastolic blood pressure. These findings suggest that cardiovascular reactivity to a mental stressor known to produce beta-adrenergically mediated responses may be lower in some normotensive blacks compared to their white counterparts.     

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.     

Pain sensitivity in offspring of hypertensives at rest and during baroreflex stimulation

Healthy males with a parental history of hypertension (PH+) showed reduced pain sensitivity to a constrictive thigh-cuff pressure stimulus as compared to individuals without a parental history of hypertension. The protocol included eight trials in which a thigh-cuff was inflated until the subject reported the stimulus to be painful. The PH+ group exhibited significantly lower pain sensitivity as indicated by (1) higher levels of constrictive pressure when pain was first reported and (2) lower subjective pain ratings at maximum constrictive pressure. To assess the role of baroreflex stimulation on pain sensitivity in these groups, four trials were administered concurrently with external carotid pressure stimulation. There were no significant differences in pain sensitivity in each group as a function of baroreflex stimulation. The results suggest that the hypoalgesia observed in hypertensives may predate the development of sustained elevations in blood pressure.     

Reproducible increases in blood pressure during intermittent noise exposure: underlying haemodynamic mechanisms specific to passive coping

Summary The purpose of the present study was to investigate the reproducibility of the increases in blood pressure found in our recent study on exposure to intermittent noise, to confirm the haemodynamic mechanism raising blood pressure (via an increase in peripheral vascular resistance expected to be specific to passive coping), and to assess baroreceptor cardiac reflex sensitivity in connection with the blood pressure elevation. A group of 16 young normotensive men participated in the experiment and underwent a 10-min intermittent exposure to pink noise at 100 dB (sound pressure level). The subjects also underwent three other stresses: a 1-min cold pressor test, a 3-min isometric handgrip and 3-min of mental arithmetic. The results indicated that blood pressure was elevated reproducibly for most of the noise exposure periods and that peripheral vascular resistance increased simultaneously, as expected. Baroreflex sensitivity was not suppressed. The results, as a whole, were in agreement with our recent findings for exposure to a similar type of noise and thus the reproducibility was corroborated. The mechanism raising blood pressure was similar in the cold pressor test. Conversely, during the isometric handgrip and mental arithmetic, blood pressure elevations were attributable mainly to increases in cardiac output. The implications of the opposing haemodynamic mechanisms raising blood pressure among the four stressful tasks have been discussed in relation to active versus passive coping required for each task. Differences in the magnitude of suppression observed in baroreflex sensitivity among the tasks have also been discussed in the context of defence reactions.     

The Effects of Caffeine and Stress on Blood Pressure in Individuals with and without a Family History of Hypertension

The effects of two doses of caffeine (125 mg, 250 mg) were compared to a placebo dose (3 mg) in a randomized double-blind cross-over design in 36 male caffeine users, half with and half without a family history of hypertension. Systolic blood pressure, heart rate, and respiration were recorded during rest, a mental arithmetic task, and recovery periods. I inter both resting and mental stress conditions, the two doses of caffeine on the average increased systolic pressure by 6.7 mini In compared to the placebo. The effects for the 125 me and 250 mg doses did not differ significantly. The pressor effects of caffeine and mental stress combined in an additive fashion. Systolic blood pressure levels were significantly greater in individuals with a family history of hypertension across all conditions, but not specifically in response to caffeine. The results arc comparable to those previously reported in caffeine-naive subjects.