Guido L. R. Godaert

Cardiovascular and endocrine responses to experimental stress: Effects of mental effort and controllability

The objective of the study was to investigate the unique and interactive effects of the controllability of a task and mental effort required by that task on cardiovascular and endocrine reactivity, when both were manipulated independently. A 2 x 2 factorial design was used, with two levels of mental effort and two levels of control. Twenty-four healthy male subjects participated in each experimental condition. Heart rate, blood pressure, catecholamine and cortisol responses were determined. High effort lead to greater increases in heart rate, blood pressure and norepinephrine levels. Uncontrollability lead to higher cortisol, blood pressure and norepinephrine responses. In addition, there was an effort x control interaction effect on the diastolic blood pressure response. In conclusion, effort has clear sympathetic effects, whereas control influences both the sympathetic nervous system and the release of cortisol. Having control seems to be most beneficial in high effort situations, at least with respect to sympathetic reactivity.

Effects of beta-adrenergic blockade on immunologic and cardiovascular changes induced by mental stress.

BackgroundAcute mental stress evokes responses in the cardiovascular and the immune systems. In particular, the subset of natural killer (NK) cells is found to be responsive to mental stress. The role of β-adrenergic mechanisms in these processes is the subject of this investigation. Methods and ResultsHealthy male volunteers (n=31) were subjected to two consecutive mental tasks. Subjects were randomly assigned to a β-blocker (propranolol 40 mg) or a placebo group. The capsules were ingested 1 hour before the tasks. The tasks evoked sympathetic responses, as indicated by an increase in heart rate and a decrease in the preejection period. These effects were abolished under β-blockade, indicating that effective β-blockade was achieved. In the immune system, significant increases were found for the number of NK cells and NK cell activity in the placebo group; these increases were absent in the propranolol group. In addition, an increase in all lymphocyte subsets was observed in subjects who had ingested propranolol. This increase, however, was also observed in subjects who had received propranolol but had not performed the tasks, indicating that these non-subset-specific increases in lymphocytes were a side effect of the βblocker. ConclusionsMental stress induces activation of the sympathetic nervous system, with concomitant increases in the number of NK cells in the circulation. These changes were inhibited by propranolol, indicating that stress-induced increases in the number and activity of NK cells in the circulation are controlled by a β-adrenergic mechanism.

Cardiovascular and Immune Responses to Acute Psychological Stress in Young and Old Women: A Meta-Analysis

Objective To describe the relationships between cardiovascular and natural killer (NK) cell number changes on acute psychological stress in women. Method Data from eight different studies were analyzed. A total of 128 healthy female subjects, 85 younger (18-45 years) and 43 older (49-87 years), had been subjected to a speech stressor (N = 80) or a mental effort stressor (N = 48), mental arithmetic, or the Stroop test. Correlations between changes in NK cell numbers, systolic (SBP) and diastolic (DBP) blood pressure, and heart rate (HR) were computed. Meta-analysis programs were used to study correlations across studies and to examine whether correlations differed with stressors or age. Results In all studies, significant increases over baseline were observed for each variable. Across studies, the mean weighted r between changes in HR, DBP, and SBP was medium (rw = .25) to large (rw = .64). A medium to large average correlation between HR and NK changes (rw = .37) was observed, whereas average correlations of changes in NK cell numbers with blood pressure changes were small to medium (rw <or=to .23). Correlations between changes in NK cell numbers and cardiovascular variables were homogeneous across studies, whereas mutual correlations between cardiovascular variables were heterogeneous. One moderator variable showed itself: correlations between HR and DBP reactions were larger in studies with older than younger subjects. Conclusion NK cell changes and HR responses induced by acute stress in women are regulated, to some extent, by the same mechanisms. Neither the type of stressor nor age seem to be very important when considering correlations between NK cell and cardiovascular changes. This study integrates information about NK cell and cardiovascular responses in women that can be used as reference material in future studies.

The validity and reliability of the Dutch Effort-Reward Imbalance Questionnaire

The reliability and validity of the Effort-Reward Imbalance Questionnaire were tested in 775 blue- and white-collar workers in the Netherlands. Cronbachs alpha revealed sufficient internal consistency of all subscales except Need for Control. With exploratory probabilistic scaling (Mokken) analysis, the psychometric qualities of the Need for Control scale were improved. With confirmatory factor analysis, the factorial validity of the Extrinsic Effort and Reward subscales was confirmed. A model with 3 separate dimensions for reward (status control, esteem reward, and monetary gratification) proved adequate, emphasizing the importance of distinguishing subscales. The congruent validity of the subscales and a hypothesized relationship with an external construct, health functioning, were confirmed.

Cortisol secretion throughout the day, perceptions of the work environment, and negative affect

The effects of explanatory variables derived from a work stress model (the effort-reward imbalance model) on salivary cortisol were assessed. A multilevel analysis was used to distinguish the effects of single occasion and multiple occasion measurements of work stress and effect on cortisol. The single (or cross-sectional) factors include Effort-Reward Imbalance (ERI), need for control, negative affect, and other enduring factors (type of occupation, gender, and smoking). The multiple occasion measurements include momentary negative mood, Momentary Demand-Satisfaction Ratio (MD-SR), sleep quality, work load (workday versus day off), at work (versus not being at the workplace), and lunch. The effect of time of day on cortisol was controlled for before the effects of these variables were determined.Momentary negative mood but not trait negative affect was positively associated with ambulatory measured cortisol. The variables from the work stress model—effort, reward, need for control, and the multiple occasion measurements of demand and satisfaction—did not affect cortisol. As could be expected, time of day had an effect on cortisol, but a hypothesised interaction with momentary negative mood was not found. Additionally, the results show that the time course of cortisol differs between individuals and that the effect of sleep quality on cortisol can vary from person to person. This points to the necessity of continued efforts to single out sources of individual variability.The finding that variables derived from the effort-reward imbalance model are not related with cortisol does not support the hypothesis that ERI leads to short-term changes in cortisol, indicating no relation with hypothalamic-pituitary-adrenal (HPA) axis activity. On the other hand, the present results invite further qualification of negative affect as a potential determinant of HPA activity, at least, as far as can be deduced from cortisol measurements.

Vagal cardiac control throughout the day: the relative importance of effort-reward imbalance and within-day measurements of mood, demand and satisfaction

The effects of variables derived from a work stress theory (the effort-reward imbalance theory) on the power in the high frequency (HF_HRV) band of heart rate (0.14-0.40 Hz) throughout a work day, were determined using multilevel analysis. Explanatory variables were analysed at two levels: at the lowest level (within-day level), the effects of positive mood, negative mood, demand, satisfaction, demand-satisfaction ratio, and time of day were assessed. At the highest level (the subject level), the effects of sleep quality, effort, reward, effort-reward imbalance, need for control, type of work (profession), negative affectivity, gender and smoking on HF_HRV were assessed. Need for control has a negative effect on HF_HRV after controlling for time of day effects, i.e. subjects with a high need for control have a lower vagal control of the heart. In the long run, these subjects may be considered to be at increased health risk, because they have less of the health protective effects of vagal tone. The interaction between effort-reward imbalance and time of day has a positive effect on HF_HRV, i.e. the cardiac vagal control of subjects with a high effort-reward imbalance increases as the day progresses. It is discussed that this probably reflects reduced effort allocation, ensuing from disengagement from the work demands.

COPING STYLES AND HEALTH

Abstract The present study aims to clarify whether strategies that people use to handle stressful situations cluster into global coping styles and whether such coping styles would be related to subjective health parameters. In previous literature ‘coping styles’ have been treated under many labels (e.g. ways of coping, defence mechanisms, personality traits, appraisal strategies) and have been assessed by many instruments. There are, however, few studies on the relationships between these concepts and instruments. In this study 254 male high school teachers were tested with the Utrecht Coping List, the Defence Mechanism Inventory, the Life Style Index and the Internal, Powerful Others and Chance locus of control scales. In addition, the teachers filled out questionnaires on stressful events and on psychological and physical health complaints. Factor analysis showed four interpretable clusters of coping styles: two clusters with defensive strategies (‘cognitive defence’ and ‘defensive hostility’) and two clusters with coping styles (‘instrumental mastery-oriented coping’ and ‘emotion-focused coping’). The ‘instrumental mastery-oriented coping’ and ‘cognitive defence’ factor played a positive moderating role in the effect of stressful situations on subjective health parameters.

Effect of dehydroepiandrosterone administration on fatigue, well-being, and functioning in women with primary Sjögren syndrome: a randomised controlled trial

Objective: Dehydroepiandrosterone (DHEA) administration has been reported to improve fatigue, psychological distress, and physical disability. These are common features of primary Sjögren syndrome (pSS). We investigated the effects of DHEA administration on fatigue, well-being, and functioning in women with pSS. Methods: In a double-blind, randomised placebo-controlled clinical trial, 60 female patients with pSS received 200 mg oral DHEA or placebo. Primary outcome measures were general fatigue, depressive mood, mental well-being, and physical functioning. In addition, pain, sicca complaints and disease activity parameters were measured. Patients were assessed before treatment, after 3, 6, and 12 months on study medication, and 6 months after cessation of treatment. Results: Patients from both the DHEA- and placebo-treated group improved on general fatigue (p<0.001), mental well-being (p = 0.04), and depressive mood (p = 0.008). Physical functioning did not change (p = 0.44). Of the secondary outcome variables, complaints of a dry mouth diminished during treatment in both groups (p = 0.006), the erythrocyte sedimentation rate showed a decrease for the DHEA group (p = 0.02), and complaints of dry eyes improved in the placebo group (p = 0.01). The belief to have used DHEA was a stronger predictor for improvement of fatigue and well-being than the actual use of DHEA. Conclusions: Our study does not support a superior effect of DHEA over placebo in female patients with pSS. Both DHEA and placebo induce improvement of fatigue and well-being. This may suggest possibilities for cognitive behavioural interventions.

Immune responses to experimental stress: effects of mental effort and uncontrollability.

OBJECTIVE Two important determinants of physiological stress responses have been identified, uncontrollability of the stressor and amount of effort involved in coping with the stressor. In the present experiment, we tried to identify the specific contributions of effort and uncontrollability to immune system responses to stress. METHODS In a 2 x 2 design, effort and uncontrollability were manipulated independently of each other. Subjects participated in one of four experimental conditions, and their endocrine, immune, and sympathetic nervous system responses to the task were assessed. RESULTS Effort had a stimulating effect on enumerative immunological parameters (CD8 and CD16+ cells) and on natural killer cell activity. The effect occurred immediately after the stressor and was transient. Regression models indicated that this effort effect may have been mediated by activation of the sympathetic nervous system. Uncontrollability influenced in vitro production of the cytokine interleukin-6, leading to decreased production 15 and 30 minutes after the stressor. Uncontrollability also led to an increased level of cortisol, but no evidence was found that the decrease in cytokine production was mediated by cortisol release. CONCLUSION The results suggest that two major stressor characteristics, effort and uncontrollability, may have differential effects on the immune system.

INTERNAL, POWERFUL OTHERS AND CHANCE LOCUS OF CONTROL: RELATIONSHIPS WITH PERSONALITY, COPING, STRESS AND HEALTH

Abstract In this paper, the relationship was studied between the internal, powerful others and chance (IPC)-scales and a range of other psychological characteristics, self-reported life stress and health complaints. The data were gathered in a large Dutch sample consisting of different groups. The factor structure and reliability of the Dutch translation were highly comparable with those of the original version. A comparison of the IPC-scales with a Rotter derived unidimensional scale shows that the latter assesses mainly chance oriented external locus of control. Furthermore, the IPC-scales in this study are differentially related to personality traits, measurements of subjective stress and self-reported health symptoms. These relationships allow a more articulate interpretation of the scales. Salient new results are e.g. that the P-scale is more strongly related to passive coping strategies, while the C-scale is more related to psychopathological symptoms and to social inadequacy. Subjects scoring high on the I-scale evaluate life events more positively, use active coping strategies, and also express their anger more often. The results partly confirm reported findings of other authors concerning the validity of the scales, and are indicative of the usefulness and meaning of the IPC-scales.