Individual differences in heart rate response during behavioral challenge

Maternal Sensitivity Modulates Child's Parasympathetic Mode and Buffers Sympathetic Activity in a Free Play Situation

Background

Behavioral and physiological (self-)regulation in early life is crucial for the understanding of childhood development and adjustment. The autonomic nervous system (ANS) is a main player in the regulative system and should therefore be modulated by the quality of interactive behavior of the caregiver. We experimentally investigated the ANS response of 18–36-month-old children in response to the quality of maternal behavior during a mother–child-interacting paradigm.

Method

Eighty mothers and their children came to our laboratory and took part in an experimental paradigm, consisting of three episodes: a resting phase (E1), a structured play phase (E2), and a free play situation (E3) between mothers and their child. Children’s and mother’s heart rate (HR), the sympathetic nervous system (SNS) activity via the pre-ejection period (PEP) and the left ventricular ejection time (LVET), and the parasympathetic nervous system (PNS) activity via the respiratory sinus arrhythmia (RSA) were continuously measured by an electrocardiogram. Maternal sensitivity of interactive behavior was assessed by using the Emotional Availability (EA) Scales.

Results

Children of mothers with insensitive behavior had a significantly lower RSA at baseline, showed a lack of RSA withdrawal during structured and free play, and had shorter LVET across all episodes compared to children of sensitive mothers.

Conclusion

Our findings depict the influence of low-quality maternal interaction on the child’s ANS regulation, in calm and more stressful play situations. The overall higher SNS mode with impaired PNS reactivity may negatively influence child’s ANS homoeostasis, which may result in a long-term impact on mental and physical wellbeing. Further, the maternal sensitivity may function as a buffer for the stress response of their child. These results could serve as a basis for the development of appropriate psychoeducational programs for mothers of low sensitivity in their interaction with the child.

Automatic Assessment of Loneliness in Older Adults Using Speech Analysis on Responses to Daily Life Questions

Loneliness is a perceived state of social and emotional isolation that has been associated with a wide range of adverse health effects in older adults. Automatically assessing loneliness by passively monitoring daily behaviors could potentially contribute to early detection and intervention for mitigating loneliness. Speech data has been successfully used for inferring changes in emotional states and mental health conditions, but its association with loneliness in older adults remains unexplored. In this study, we developed a tablet-based application and collected speech responses of 57 older adults to daily life questions regarding, for example, one's feelings and future travel plans. From audio data of these speech responses, we automatically extracted speech features characterizing acoustic, prosodic, and linguistic aspects, and investigated their associations with self-rated scores of the UCLA Loneliness Scale. Consequently, we found that with increasing loneliness scores, speech responses tended to have less inflections, longer pauses, reduced second formant frequencies, reduced variances of the speech spectrum, more filler words, and fewer positive words. The cross-validation results showed that regression and binary-classification models using speech features could estimate loneliness scores with an R 2 of 0.57 and detect individuals with high loneliness scores with 95.6% accuracy, respectively. Our study provides the first empirical results suggesting the possibility of using speech data that can be collected in everyday life for the automatic assessments of loneliness in older adults, which could help develop monitoring technologies for early detection and intervention for mitigating loneliness.

Reduced caregiving quality measured during the strange situation procedure increases child's autonomic nervous system stress response

BACKGROUND

Dysfunctional maternal behavior has been shown to lead to disturbances in infant's regulatory capacities and alterations in vagal reactivity. We aim to investigate the autonomic nervous system (ANS) response of the child during the strange situation procedure (SSP) in relation to the quality of maternal behavior.

METHODS

Twelve month after birth, 163 mother-child-dyads were investigated during the SSP. Heart rate (HR) and both, the parasympathetic branch (PNS) via the respiratory sinus arrhythmia (RSA) and the sympathetic branch (SNS) via the left ventricular ejection time (LVET) of the ANS were continuously determined during the SSP using electrocardiogram (ECG) and impedance cardiogram (ICG) measures. Maternal behavior was assessed by using the AMBIANCE measure.

RESULTS

The ANS response in infants of mothers with disruptive behavior compared to infants of non-disruptive mothers was significantly altered during the SSP: HR increased especially when infants of disruptive mothers were alone with the stranger (F (1, 161) = 4.15, p = .04) with a significant vagal withdrawal when being in contact with the stranger despite of presence of the mother (F (1, 161) = 5.11, p = .03) and a significant increase in vagal tone during final reunion (F (1, 161) = 3.76, p = .05). HR increase was mainly based on a decrease in LVET (F (1, 161) = 4.08, p = .05) with a maximum infant's HR when the stranger came into the room instead of the mother.

CONCLUSION

Both, SNS and PNS branches of the child are significantly altered in terms of an ANS imbalance, especially during contract to a stranger, in relation to dysfunctional maternal behavior. Our findings suggest the importance of supporting high quality caregiving that enables the infant to adapt adequately to stressful interpersonal situations which is likely to promote later health.

Individual differences in cardiorespiratory measures of mental workload: An investigation of negative affectivity and cognitive avoidant coping in pilot candidates

Cardiorespiratory measures provide useful information in addition to well-established self-report measures when monitoring operator capacity. The purpose of our study was to refine the assessment of operator load by considering individual differences in personality and their associations with cardiorespiratory activation. Physiological and self-report measures were analyzed in 115 pilot candidates at rest and while performing a multiple task covering perceptual speed, spatial orientation, and working memory. In the total sample and particularly in individuals with a general tendency to worry a lot, a cognitive avoidant coping style was associated with a smaller task-related increase in heart rate. Negative affectivity was found to moderate the association between cardiac and self-reported arousal. Given that physiological and self-report measures of mental workload are usually combined when evaluating operator load (e.g., in pilot selection and training), our findings suggest that integrating individual differences may reduce unexplained variance and increase the validity of workload assessments.

Loneliness and cognitive function in the older adult: a systematic review

BACKGROUND

Loneliness is a significant concern among the elderly, particularly in societies with rapid growth in aging populations. Loneliness may influence cognitive function, but the exact nature of the association between loneliness and cognitive function is poorly understood. The purpose of this systematic review was to synthesize current findings on the association between loneliness and cognitive function in older adults.

METHOD

A comprehensive, electronic review of the literature was performed. Criteria for inclusion were original quantitative or qualitative research, report written in English, human participants with a mean age ≥ 60 years, and published from January 2000 through July 2013. The total number of studies included in this systematic review was ten.

RESULTS

Main findings from the ten studies largely indicate that loneliness is significantly and negatively correlated with cognitive function, specifically in domains of global cognitive function or general cognitive ability, intelligence quotient (IQ), processing speed, immediate recall, and delayed recall. However, some initial correlations were not significant after controlling for a wide range of demographic and psychosocial risk factors thought to influence loneliness.

CONCLUSIONS

Greater loneliness is associated with lower cognitive function. Although preliminary evidence is promising, additional studies are necessary to determine the causality and biological mechanisms underlying the relationship between loneliness and cognitive function. Findings should be verified in culturally diverse populations in different ages and settings using biobehavioral approaches.

The genetic and environmental etiology of sympathetic and parasympathetic activity in children

The present study examines the genetic and environmental etiology of the associations among respiratory sinus arrhythmia (RSA), heart rate (HR), skin conductance level (SCL), and non-specific skin conductance responses (NS-SCR)-measures that purportedly index the parasympathetic and sympathetic branches of the autonomic nervous system. The sample was drawn from a cohort of 1,219 preadolescent twins (aged 9-10). Multivariate analyses of the data were conducted using structural equation modeling. Almost all genetic and environmental influences on the measures acted through two latent factors. The first latent factor was largely responsible for the variance in heart rate, SCL and NS-SCR, reflecting sympathetic activity, and its proportions of variance due to genetic and shared environmental influences were 27 and 28% in males, and 31 and 41% in females, respectively. The second latent factor accounted for the variance in RSA and heart rate, reflecting parasympathetic activity; genetic and shared environmental factors explained 27 and 23% of the variance in males, respectively, and 35 and 18% of the variance in females. Measurement-specific genetic effects accounted for 14-27% of the total variance in RSA and SCL, and measurement-specific shared environmental effects accounted for 10-12% in SCL. In general, the validity of separate sympathetic and parasympathetic constructs was supported.

Development of a multi-channel exploratory battery for psychophysiological assessment: the Stress Profile

OBJECTIVE

As the expanding field of psychophysiology is currently demanding applied methodologies to be used in the clinic, this study aimed to develop a practical multi-channel exploratory battery for psychophysiological evaluation of stress (the Psychophysiological Stress Profile; PSP). The PSP records 6 psychophysiological variables and it is designed to be mainly used in the daily clinic. Moreover, the PSP was intended to be 'the method' to obtain normative and individual psychophysiological patterns, providing relevant information for the therapeutic process.

METHODS

Two hundred and three subjects were evaluated with the PSP in two different contexts: the natural environment and the laboratory. Factorial analysis was applied to obtain psychophysiological profiles. These profiles are based on the covariation among different system responses. The Burt and Tucker Congruence Coefficient was used to compare factorial structures.

RESULTS

A 3-factor structure was obtained in both contexts, Congruence Coefficient indicates that these factorial structures are very similar, indicating the existence of a unique and consistent psychophysiological pattern that characterizes the sample.

CONCLUSIONS

The identified factorial structure shows relevant activation patterns, offering a comprehensive view of the subject's functioning. The structure is consistent through samples and can be considered as normative data for the studied population. PSP has turned out to be a quick and easy-to-use psychophysiological battery that has shown adequate internal consistency for all the recorded variables. In this way, the PSP methodology shows its practical value and usefulness in the assessment process.

Loneliness and pathways to disease

Social isolation predicts morbidity and mortality from cancer, cardiovascular disease, and a host of other causes. The mechanisms by which the social world impacts on health are poorly understood, in part because of lack of specificity in the conceptualization and operationalization of relevant aspects of social relationships and physiological processes. Perceived social isolation, commonly termed loneliness, may represent a link between the epidemiological and biological levels of analysis. Research is presented that investigates loneliness as a social factor of importance in three predisease pathways: health behaviors, excessive stress reactivity, and inadequate or inefficient physiological repair and maintenance processes. Empirical evidence of autonomic, endocrine, and immune functioning suggests that the physiological effects of loneliness unfold over a relatively long time period. For cancer patients, interventions should be aimed at providing instrumental support for the immediate demands of the disease.

Autonomic reactivity and psychopathology in middle childhood

BACKGROUND

Better indicators are needed for identifying children with early signs of developmental psychopathology.

AIMS

To identify measures of autonomic nervous system reactivity that discriminate children with internalising and externalising behavioural symptoms.

METHOD

A cross-sectional study of 122 children aged 6--7 years examined sympathetic and parasympathetic reactivity to standardised field-laboratory stressors as predictors of parent- and teacher-reported mental health symptoms.

RESULTS

Measures of autonomic reactivity discriminated between children with internalising behaviour problems, externalising behaviour problems and neither. Internalisers showed high reactivity relative to low-symptom children, principally in the parasympathetic branch, while externalisers showed low reactivity, in both autonomic branches.

CONCLUSIONS

School-age children with mental health symptoms showed a pattern of autonomic dimorphism in their reactivity to standardised challenges. This observation may be of use in early identification of children with presyndromal psychopathology.

Selective reduction in CD2 expression on CD2bright/CD8+ lymphocytes from cynomolgus monkeys (Macaca fascicularis) in response to acute stress

Numerous reports have demonstrated a link between stressful stimuli and immune suppression. However, the cellular mechanisms by which stress impairs immune function are largely unknown. We have examined the effects of an acute stressor on the T cell population, specifically, the number and phenotype of T cells in a nonhuman primate model. In nonstressed adult monkeys, we found differences in the level of expression of CD2 on T cells, revealing two distinct subsets of T cells, CD2dim and CD2bright cells, with CD2bright cells predominately coexpressing CD8. In response to acute stress, we observed a significant loss in the number and percent of CD2bright/CD8+ cells, with percent of CD2bright cells returning to pre-stress values within 24 h.

Autonomic, neuroendocrine, and immune responses to psychological stress: the reactivity hypothesis

We examined the effects of brief psychological stressors on cardiovascular, neuroendocrine, and cellular immune response in 22 older women to investigate the common effects of stress across systems. Results revealed that psychological stressors heightened cardiac sympathetic activation, elevated plasma catecholamine concentrations, and affected the cellular immune response (ps < 0.05). In a replication and extension, 27 women caring for a spouse with a progressive dementia (high chronic stress) and 37 controls category matched for age and family income (low chronic stress) performed the 12-min laboratory stressor. Measures were taken before (low acute stress) and immediately following (high acute stress) exposure to the laboratory stressors as well as 30 min after termination of the stressor (recovery period). Acute stress again heightened cardiac sympathetic activation, elevated plasma catecholamine concentrations, and affected cellular immune responses (ps < 0.05), whereas chronic stress was associated with higher reports of negative affect, enhanced cardiac sympathetic activation, elevated blood pressure and plasma levels of ACTH, and diminished production of interleukin-1 beta (ps < 0.05). Correlational analyses in both studies further suggested that individuals who showed the greatest stress-related changes in HPA activation also exhibited the greatest diminution in cellular immune response.

The effects of blood pressure resting level and lability on cardiovascular reactions to laboratory stress

Evidence that individuals with elevated resting blood pressures display excessive cardiovascular reactions to laboratory stress is regarded as implicating excessive reactivity in the pathogenesis of hypertension. However, it remains possible that this relationship is artifactual, in that resting blood pressure levels and cardiovascular reactions might both reflect intrinsic cardiovascular lability. To examine this possibility, blood pressure and heart rate were measured at rest and in response to an active laboratory stressor in 1259 men. Systolic blood pressure and heart rate reactions to the stressor were predicted by resting blood pressure. Although cardiovascular lability showed some association with both reactivity and resting blood pressure level, the resting blood pressure level-reactivity relationship survived statistical adjustment for such associations. Accordingly, the excessive cardiovascular reactions characteristic of individuals with elevated resting blood pressure would not appear to be explainable, to any substantial extent, by lability effects.

Illusions, arithmetic, and the bidirectional modulation of vagal control of the heart

Behavioral contexts can evoke a variety of autonomic modes of response, characterized by reciprocal, coactive, or independent changes in the autonomic divisions. The present study investigated the modes of autonomic response to visual illusion and mental arithmetic tasks, by the use of noninvasive measures of sympathetic (pre-ejection period; PEP) and parasympathetic (respiratory sinus arrhythmia; RSA) cardiac control. As previously demonstrated, mental arithmetic was associated with a reciprocal pattern of sympathetic activation and vagal withdrawal. The illusion task, however, yielded a distinct mode of vagal activation in the absence of sympathetic change. Responses within tasks were reliable. In contrast to the general intertask consistency reported for stress tasks that yield similar autonomic modes of response, however, neither PEP nor RSA responses were correlated across the illusion and arithmetic tasks. This may be attributable to the dissimilar modes of autonomic control evoked by these tasks. The distinct modes of autonomic response to arithmetic and illusions emphasize the importance of a bivariate model of autonomic control, and may offer important experimental tools for psychophysiological studies of autonomic control.

Heterogeneity in neuroendocrine and immune responses to brief psychological stressors as a function of autonomic cardiac activation

Human responses to brief psychological stressors are characterized by changes and large individual differences in autonomic, neuroendocrine, and immune function. The authors examined the effects of brief psychological stressors on cardiovascular, neuroendocrine, and cellular immune response in 22 older women to investigate the common effects of stress across systems. They also used interindividual variation in heart rate reactivity, cardiac sympathetic reactivity (as indexed by preejection period reactivity in their reactivity paradigm), and cardiac vagal reactivity (as indexed by respiratory sinus arrhythmia reactivity) to explore the heterogeneity in human responses to brief psychological stressors. The results revealed that brief psychological stressors heightened cardiac activation, elevated plasma catecholamine concentrations, and affected the cellular immune response. It was also found that individuals characterized by high, relative to low, cardiac sympathetic reactivity showed higher stress-related changes in adrenocorticotropic hormone and cortisol plasma levels but comparable changes in epinephrine and norepinephrine concentrations. These data suggest that the effects of psychological stressors on cardiovascular and cellular immune response are governed by coordinated regulatory mechanism(s) and that going beyond the simple notion of heart rate reactivity to examine neural substrates may shed light on the interrelationships among and the regulatory mechanisms for the autonomic, endocrine, and immune responses to stressors.

Autonomic cardiac control. III. Psychological stress and cardiac response in autonomic space as revealed by pharmacological blockades

Behavioral contexts can evoke a variety of autonomic modes of response, characterized by reciprocal, coactive, or independent changes in the autonomic divisions. In the present study, we investigated the reactive autonomic control of the heart in response to psychological stressors, using quantitative methods for analyzing single and double autonomic blockades, and through the use of noninvasive indices based on heart period variability and systolic time intervals. Analysis of the effects of pharmacological blockades revealed an overall pattern of increased sympathetic and decreased parasympathetic control of the heart during speech stress, mental arithmetic, and a reaction-time task. Unlike the classical reciprocal sympathetic-parasympathetic response to orthostatic challenge, however, the responses of the autonomic branches to stress were uncorrelated. This reflected notable individual differences in the mode of autonomic response to stress, which had considerable stability across stress tasks. The putative noninvasive indices of sympathetic (preejection period) and parasympathetic (respiratory sinus arrhythmia) control changed in accord with the results of pharmacological blockades. Together, these results emphasize the substantial individual differences in the mode of autonomic response to stress, the advantages of a quantitative approach to analyzing blockade data, and the importance of validity estimates of blockade data.

Individual differences in the autonomic origins of heart rate reactivity: the psychometrics of respiratory sinus arrhythmia and preejection period

Heart rate reactivity has been conceptualized, at least implicitly, as a unidimensional construct ranging from low to high, reflecting individual differences in adrenergic reactivity to daily stressors. However, an individual's classification as high in heart rate reactivity ignores possible individual differences in the autonomic origins of this reactivity. Sixty-eight women were exposed to orthostatic and speech stressors to determine the psychometric properties (postural stability, convergent and discriminant validity) of heart rate, preejection period, and respiratory sinus arrhythmia. Results revealed that (a) basal, stress, simple reactivity (stress - baseline), and residualized change indices of heart rate, preejection period, and respiratory sinus arrhythmia were stable across postures and (b) heart rate reactivity was significantly related to preejection period and respiratory sinus arrhythmia reactivity, whereas the latter two measures were unrelated. Reactivity classifications may therefore be significantly improved by attention to concurrent estimates of the activity of both autonomic branches.

The effects of an acute psychological stressor on cardiovascular, endocrine, and cellular immune response: a prospective study of individuals high and low in heart rate reactivity

High and low reactors were preselected on the basis of their heart rate reactivity to a speech stressor in a prescreening session. In the main study, subjects were exposed to a mental arithmetic plus noise stressor. Cardiovascular activity was recorded during baseline and stressor, and blood was drawn prior to and following the stressor for endocrine and immune assays. Results revealed that the stressor decreased the blastogenic response to concanavalin A and increased natural killer cell numbers and cytotoxicity, absolute numbers of CD8+ T-lymphocytes, norepinephrine and epinephrine levels, heart rate, and blood pressure responses. In addition, cortisol and natural killer cell cytotoxicity responses to the stressor differentiated individuals high versus low in heart rate reactivity. These results suggest that the interactions among the autonomic nervous system, endocrine system, and immune system are not only amenable to psychophysiological analysis but that such analyses may play an important role in illuminating underlying mechanisms.

Social neuroscience: autonomic, neuroendocrine, and immune responses to stress

The immune system is influenced by central nervous system processes that are shaped by social and psychological factors. Considerations of social factors, intrapersonal process, and autonomic psychophysiology therefore may contribute to a fuller understanding of both immune and brain function. Research reviewed here (a) examines the socioemotional factors that contribute to, or moderate, responses to brief and chronic stressors, (b) determines whether or not stable individual differences in heart rate reactivity predict neuroendocrine and immune responses to a brief psychological stressor and to an influenza virus vaccine, and (c) investigates the autonomic origins of individual differences in low and high heart rate reactivity and their relationship to neuroendocrine and immune responses to chronic and acute stressors. Among our findings are: (a) acute psychological stressors activate the sympathetic adrenomedullary system across individuals and affect immune function; and (b) individuals characterized by high sympathetic cardiac reactivity to acute psychological stressors also show a relative activation of the hypothalamic pituitary adrenocortical system and altered immune function.

Symptom-specific psychophysiological responses in chronic pain patients

Symptom-specific psychophysiological responding was assessed in 20 chronic back pain patients, 20 patients suffering from temporomandibular pain and dysfunction, and 20 matched healthy controls. Surface EMG from the lower and upper back, the masseter, and the biceps muscles, and heart rate and skin conductance level were continuously recorded during adaptation, resting baseline, and stressful and neutral imagery phases. Univariate and multivariate analyses of variance were performed on raw data as well as data corrected for autocorrelation. The results showed significantly higher EMG reactivity which was lateralized to the left side at the patients' site of pain but not distal sites. This hyperreactivity was observed only during stressful imagery. The healthy controls displayed a significantly higher response in heart rate, but skin conductance level was not significantly different. The results are interpreted as indicative of idiosyncratic muscular response patterns to personally relevant situations at the site of pain in patients suffering from chronic muscular pain.

Heart rate reactivity in attention deficit disorder subgroups

Beat-to-beat heart rate (HR) was analyzed for 9 contiguous seconds in a warned reaction time (RT) paradigm. Imperative stimuli were tones of three intensity levels (55, 78, and 100 db); a visual warning signal occurred 5 sec before tone onset. Baseline and reward conditions were run. Normal controls were contrasted with three Attention Deficit Disorder (ADD) subgroups: ADD-only, ADD with hyperactivity (ADDH), ADD with hyperactivity and aggression (ADDHA). The ADD subgroups were predicted to show less deceleration in HR because of their problem sustaining readiness to respond. Significant sex x group differences in HR levels and change scores were found. Overall, girls had higher HR levels than boys and the ADD-only group (boys and girls) had lower HRs than the other ADD groups. But, the ADD-only boys had more marked deceleration to the warning signal and acceleration to the tones than the other ADD boys, whereas the ADD-only girls were no more reactive than the ADDH and ADDHA girls. Control girls had the highest HR levels and were the most reactive to stimuli. Control boys and ADD-only boys had similar HR levels and reaction patterns. ADD-only girls appear to be underaroused, whereas ADD-only boys do not. Results suggest that cardiac measures can provide external validation of disruptive and nondisruptive ADD subtypes.

Effect of a six-month aerobic exercise training program on cardiovascular responsivity in healthy middle-aged adults

The purpose of this study was to determine the effects of a six month aerobic exercise training regimen on cardiovascular responsivity to mental arithmetic in healthy middle-aged men and women. Subjects were randomly assigned to a moderate intensity exercise intervention or to an assessment-only control group. Before and after the intervention subjects' heart rates and blood pressures were measured doing a mental arithmetic task (N = 83). Other physiological and psychosocial measures included the Type A structured interview and a maximal exercise treadmill test. Validated adherence to the exercise regimen exceeded 75% and there were significant increases in aerobic capacity in those subjects receiving exercise training. Exercise did not significantly reduce cardiovascular responsivity to the stress task. Type A behavior did not interact with reactivity across exercisers or controls nor was it significantly correlated with adherence. The results are discussed with respect to factors that have been previously reported to potentially influence the exercise/reactivity relationship.

Generalization of cardiovascular response: supportive evidence for the reactivity hypothesis

Cardiovascular responses were monitored while 36 subjects completed a battery of laboratory stressors comprising mental arithmetic, a reaction time task, a speech task, and the forehead cold pressor. Inter-task consistency was assessed for each of 6 physiological parameters for all task pairings. Considerable inter-task consistency for reactivity scores was seen among the psychological stressors for all variables. The question of such consistency between the cold pressor and the psychological tasks was then addressed. The pattern of consistency was not as clear-cut in this case. For systolic blood pressure and pre-ejection period, reactivity scores to the cold pressor did not correlate with those to any of the psychological tasks. In contrast, cardiac output and total peripheral resistance responses showed considerable consistency. The importance of determining the nature of the relationship between psychological and physical stressors is discussed.

Children's cardiovascular reactivity: stability of racial differences and relation to subsequent blood pressure over a one-year period

After measuring blood pressure and heart rate at rest and during a video game procedure in 477 children enrolled in 3rd grade, 434 (91%) children had these measurements repeated a year later in 4th grade. Black children demonstrated greater blood pressure and heart rate reactivity than White children in both years, and an increase in heart rate reactivity from 3rd to 4th grade. Gender effects were inconsistent. Systolic and diastolic blood pressures during the video game were more highly correlated from year-to-year than were the resting measures. Regression analysis indicated that systolic reactivity was significantly related to subsequent systolic pressure at rest, particularly among Black girls. Diastolic reactivity was associated with subsequent resting diastolic pressure only among White children. Associations between reactivity and future blood pressure were independent of initial resting blood pressure. This study suggests that cardiovascular reactivity to psychological stress may be one important factor in future level of blood pressure and that the increased heart rate reactivity of Black children may be associated with the prevalence of hypertension among Black adults.

Postural effects on blood pressure reactivity: implications for studies of laboratory-field generalization

This study was designed as an in-laboratory evaluation of the significance of postural blood pressure (BP) adjustments in the investigation of laboratory-field generalization. Blood pressure responses were monitored while 20 subjects completed a mental arithmetic task in two postures, seated and standing. Baseline data were also collected in each posture. The standing challenge was regarded as a laboratory representation of real-world standing challenges. Reactivity scores for the seated stressor were calculated as seated task level minus seated baseline level. For the standing stressor, they were calculated in two ways; standing task level minus standing baseline, and standing task level minus seated baseline. It was hypothesized that the standing reactivity scores calculated from standing baselines (i.e. from the same-posture baselines) would be more highly correlated with seated reactivity than would the standing reactivity scores calculated using sitting baselines. This was not found to be the case for either SBP or DBP. Absolute task SBP levels were very similar in both postures, while they were significantly different for DBP, with standing task levels being higher. It was concluded that ignoring posture will not mask SBP reactivity associations between laboratory and field, but that it may do so for DBP, particularly in future studies as our overall understanding of laboratory-field generalization increases.

Temporal stability of the hemodynamics of cardiovascular reactivity

Cardiovascular responses to a competitive reaction-time task were monitored in 13 male subjects tested twice, 3 months apart. The temporal stability of blood pressure responses was in line with previous reports. However, in this study impedance cardiography permitted the investigation of the hemodynamic adjustments underlying the observed blood pressure responses. Analyses revealed that cardiac output and total peripheral resistance responses displayed temporal stability, indicating that subjects' blood pressure responses on the two occasions were the result of similar hemodynamic responses. These data thus extend the literature by demonstrating that the hemodynamic response pattern itself represents a stable individual difference variable.

Cardiovascular responses to behavioral stressors: laboratory-field generalization and inter-task consistency

Blood pressure and heart rate responses were monitored while 30 medical, dental or graduate students completed four laboratory tasks. On a second day, subjects wore an ambulatory blood pressure monitor, and during this day they completed the real-world challenge of presenting their research in front of a small audience. Heart rate and blood pressures correlated significantly between all four laboratory tasks for both absolute levels and reactivity scores (calculated as task level minus pre-task baseline level). However, while heart rate and blood pressure absolute levels for each task correlated significantly with those attained during the real-world stressor, correlation coefficients obtained when similarly comparing reactivity scores were uniformly non-significant. Laboratory-field generalization was thus evident only for absolute values. Consideration was then given to the fact that the laboratory tasks were undertaken in a seated position, while subjects stood during the real-world task. Activity diaries completed by subjects during the time they wore the ambulatory monitor were examined to search for readings that could be regarded as standing baselines. Such values were obtained for 12 of the subjects. Real-world reactivity scores were recalculated using these standing baselines, and compared again with reactivity scores during the laboratory tasks. Marked increases in correlation coefficients were obtained for systolic and diastolic pressure, but not for heart rate.