Behavioral task-induced bronchodilation in asthma during active and passive tasks: a possible cholinergic link to psychologically induced airway changes

My Life in HRV Biofeedback Research

This paper reviews the published work of me along with my students and close colleagues on the topic of heart rate variability biofeedback (HRVB). It includes early research by Vaschillo documenting resonance characteristics of the baroreflex system that causes large oscillations in heart rate when breathing at resonance frequency, research on heart rate variability as a marker of parasympathetic stress response in asthma, and HRVB as a treatment for asthma and depression. Many questions about HRVB remain unresolved, and important questions for future research are listed.

Blood pressure reaction to negative stimuli: Insights from continuous recording and analysis

Individuals with a tendency toward abnormally enhanced cardiovascular responses to stress are at greater risk of developing essential hypertension later in life. Accurate profiling of continuous blood pressure (BP) reactions in healthy populations is crucial for understanding normal and abnormal emotional reaction patterns. To this end, we examined the continuous time course of BP reactions to aversive pictures among healthy participants. In two experiments, we showed participants negative and neutral pictures while simultaneously measuring their continuous BP and heart rate (HR) reactions. In this study, BP reactions were analyzed continuously, in contrast to previous studies, in which BP responses were averaged across blocks. To compare time points along a temporal continuum, we applied a multi-level B-spline model, which is innovative in the context of BP analysis. Additionally, HR was similarly analyzed in order to examine its correlation with BP. Both experiments revealed a similar pattern of BP reactivity and association with HR. In line with previous studies, a decline in BP and HR levels was found in response to negative pictures compared to neutral pictures. In addition, in both conditions, we found an unexpected elevation of BP toward the end of the stimuli exposure period. These findings may be explained by the recruitment of attention resources in the presence of negative stimuli, which is alleviated toward the end of the stimulation. This study highlights the importance of continuous measurement and analysis for characterizing the time course of BP reactivity to emotional stimuli.

Effects of acute psychological stress induced in laboratory on physiological responses in asthma populations: A systematic review

BACKGROUND

Psychological stress has long been suspected to have a deleterious effect on asthma, with acute psychological stress being associated with physiological responses in asthma patients.

OBJECTIVES

The purpose of this systematic review was to provide a narrative synthesis of the impact of acute laboratory psychological stress on physiological responses among asthma patients.

METHODS

An extensive search was conducted by two independent authors using Pubmed, PsycINFO, PsyArticles and the Cochrane Library electronic databases (up to September 2016). English and French articles which assessed physiological responses during or post-stress and compare them to baseline or pre-stress values were included.

RESULTS

Thirty-two studies met the inclusion criteria. Studies indicated that exposure to active stressors (e.g., arithmetic tasks) was associated with an increase in sympathetic nervous system (SNS) responses, cortisol, and inflammatory responses, but had little effect on the caliber of the bronchi. Exposure to passive stressors (e.g., watching stressful movies or pictures) was also associated with an increase in SNS responses and with mild bronchoconstriction. However, a paucity of data for passive stressors limited conclusions on other measures.

CONCLUSIONS

In patients with asthma, both active and passive stressors seem to be associated with an increased activation of the SNS. Passive stressors seem to have a more immediate, deleterious impact on the airways than active stressors, but the latter may be associated with delayed inflammatory driven an asthma exacerbation. Further studies are needed to understand the impact of acute stressors on the physiological mechanisms associated with asthma, particularly HPA and immune markers. Systematic review registration number: CRD42015026431.

Airway reactivity in response to repeated emotional film clip presentation in asthma

Emotional stimuli elicit airway constriction in individuals with asthma and in healthy individuals, but little is known about effects of repeated stimulation. We therefore explored the effect of repeated emotion induction on respiratory resistance (R_rs) using unpleasant, high-arousal surgery films and investigated effects of respiration and emotional reactivity. Twenty-six participants (13 with asthma) watched a series of 12 short, 45-s surgery films followed by 2-min recovery periods. R_rs assessed with impulse oscillometry was significantly elevated during films in both groups compared to baseline and recovered quickly after that. No habituation of airway responses occurred. R_rs was higher in participants who felt more aroused and less in control when watching the films. Changes in R_rs remained significant when controlling for changes in respiration or emotional experience. Thus, although unpleasant stimuli lead to elevated R_rs, airway obstruction is not exacerbated with repeated stimulation due to a fast return to baseline after stimulation.

Measurement of stress

This article provides information on psychological assessments based on the most influential stress theories. In understanding the stress response and its relation to disease, clinical vignettes are provided. Emphasis is placed on assessment measures for use in the general population and on providing an overview of evidence for more commonly used instruments in health care. Several advantages and disadvantages afforded by measurement approaches are also addressed (although a full examination of the extent of limitations and issues regarding assessment is beyond the scope of this article). Finally, future considerations regarding proposed research and necessary advances in measurement are discussed.

Academic exam stress and depressive mood are associated with reductions in exhaled nitric oxide in healthy individuals

Nitric oxide (NO) has beneficial effects on cardiovascular and immune health. Stress and depression have been linked to a reduction in serum NO. In this study, we examined the effect of academic exam stress on the fraction of NO in exhaled air (FeNO) and spirometric lung function in 41 healthy college students. Participants completed assessments at mid-semester as well as in the early and late phase of an academic exam period. Negative affect, depressive mood, and salivary cortisol were elevated during exams, whereas FeNO and lung function decreased. Higher depressive mood was associated with lower FeNO, whereas higher negative affect was associated higher FeNO across time. These findings provide initial evidence that depression and prolonged stress can alter FeNO and lung function in healthy individuals, which could have adverse consequences for cardiovascular, airway, and immune health.

Airway responsiveness to psychological processes in asthma and health

Psychosocial factors have been found to impact airway pathophysiology in respiratory disease with considerable consistency. Influences on airway mechanics have been studied particularly well. The goal of this article is to review the literature on airway responses to psychological stimulation, discuss potential pathways of influence, and present a well-established emotion-induction paradigm to study airway obstruction elicited by unpleasant stimuli. Observational studies have found systematic associations between lung function and daily mood changes. The laboratory-based paradigm of bronchoconstrictive suggestion has been used successfully to elicit airway obstruction in a substantial proportion of asthmatic individuals. Other studies have demonstrated modulation of airway responses to standard airway challenges with exercise, allergens, or pharmacological agents by psychological factors. Standardized emotion-induction techniques have consistently shown airway constriction during unpleasant stimulation, with surgery, blood, and injury stimuli being particularly powerful. Findings with various forms of stress induction have been more mixed. A number of methodological factors may account for variability across studies, such as choice of measurement technique, temporal association between stimulation and measurement, and the specific quality and intensity of the stimulus material, in particular the extent of implied action-orientation. Research has also begun to elucidate physiological processes associated with psychologically induced airway responses, with vagal excitation and ventilatory influences being the most likely candidate pathways, whereas the role of specific central nervous system pathways and inflammatory processes has been less studied. The technique of emotion-induction using films has the potential to become a standardized challenge paradigm for the further exploration of airway hyperresponsiveness mediated by central nervous system processes.

A computerized multidimensional measurement of mental workload via handwriting analysis

The goal of this study was to test the effect of mental workload on handwriting behavior and to identify characteristics of low versus high mental workload in handwriting. We hypothesized differences between handwriting under three different load conditions and tried to establish a profile that integrated these indicators. Fifty-six participants wrote three numerical progressions of varying difficulty on a digitizer attached to a computer so that we could evaluate their handwriting behavior. Differences were found in temporal, spatial, and angular velocity handwriting measures, but no significant differences were found for pressure measures. Using data reduction, we identified three clusters of handwriting, two of which differentiated well according to the three mental workload conditions. We concluded that handwriting behavior is affected by mental workload and that each measure provides distinct information, so that they present a comprehensive indicator of mental workload.

Stress-induced respiratory pattern changes in asthma

OBJECTIVES

To build upon prior research on stress-related breathing pattern changes in asthma. Previous research has considered a limited set of respiratory parameters and has remained equivocal. Emotions and stress are known to change the respiratory pattern. In asthma, certain breathing patterns have adverse effects on the airways and lead to symptom exacerbation.

METHODS

We studied respiration during resting conditions and an acute psychosocial stressor (a free speech and mental arithmetic task) in participants with asthma (n = 20) and healthy controls (n = 19). The respiratory pattern was recorded with respiratory inductance plethysmography. Partial pressure of end-tidal carbon dioxide (PCO(2)) was measured with capnometry before and after stress.

RESULTS

The overall minute ventilation was higher in asthma (mean [standard deviation] = 9.0 [4.0] L versus 6.8 [4.1] L, p < .05), but levels of the PCO(2) were comparable (34.6 [3.5] mm Hg versus 35.0 [3.7] mm Hg, p = .667) to healthy controls during prestress and poststress phases. Participants with asthma also showed a significant lengthening of inspiration, expiration, and the total respiratory cycle during stress compared with healthy controls (p < .05). During stress tasks, all participants showed marked increases in tidal volume, inspiratory flow, minute ventilation, tidal volume instability, ribcage contribution to tidal volume, and ribcage-abdominal asynchrony. A significant increase in tidal volume instability and a tendency toward lengthening of expiration and the total respiratory cycle were observed in quiet-sitting periods at prestress to poststress in asthma.

CONCLUSIONS

Expiratory lengthening and variable tidal volumes are characteristic for individuals with asthma during psychosocial stress. The function and possible association of these changes with symptom exacerbations require further study.

Airway response to emotion- and disease-specific films in asthma, blood phobia, and health

Earlier research found autonomic and airway reactivity in asthma patients when they were exposed to blood-injection-injury (BII) stimuli. We studied oscillatory resistance (R(os)) in asthma and BII phobia during emotional and disease-relevant films and examined whether muscle tension counteracts emotion-induced airway constriction. Fifteen asthma patients, 12 BII phobia patients, and 14 healthy controls viewed one set of negative, positive, neutral, BII-related, and asthma-related films with leg muscle tension and a second set without. R(os), ventilation, cardiovascular activity, and skin conductance were measured continuously. R(os) was higher during emotional compared to neutral films, particularly during BII material, and responses increased from healthy over asthmatic to BII phobia participants. Leg muscle tension did not abolish R(os) increases. Thus, the airways are particularly responsive to BII-relevant stimuli, which could become risk factors for asthma patients.

Comparing real-life and laboratory-induced stress reactivity on cardio-respiratory parameters: differentiation of a tonic and a phasic component

To recreate stress in laboratory conditions, the nature of the elicited physiological reactions to the presentation of mental tasks has been extensively studied. However, whether this experimental response is equivalent to real-life stress reactivity is still under debate. We investigated cardio-respiratory reactivity to a sequential protocol of different mental tasks of varying difficulties, some of them involving emotional material, and repeated the measures in a baseline and in a real-life stress situation. R-R interval (RRI), breathing frequency and volumes, and respiratory sinus arrhythmia (RSA) were computed. Baseline results showed a superior sensitivity of respiratory parameters to mental task load over RRI and RSA, no effect of task difficulty or emotional material, and a habituation response of all parameters along the protocol. Stress results showed a dual effect: first, a decreased RRI and RSA in rest values, and second, a decreased reactivity in RRI in response to mental tasks. These findings are discussed through the interaction of activation, considered to be a tonic variable, and arousal, as a phasic response.

Airway response to emotional stimuli in asthma: the role of the cholinergic pathway

In asthma, airways constrict in response to emotion and stress, but underlying mechanisms, potential extrathoracic contributions, and associations with airway pathophysiology have not been elucidated. We therefore investigated the role of the cholinergic pathway in emotion-induced airway responses in patients with asthma and the association of these responses with airway pathophysiology. Patients with asthma (n=54) and healthy participants (n=25) received either 40 microg ipratropium bromide or a placebo in a double-blind double-dummy cross-over design in two laboratory sessions with experimental emotion induction. Stimuli were preevaluated films and pictures of pleasant, unpleasant, and neutral quality. Respiratory resistance and reactance at 5 and 20 Hz were measured continuously before and during presentations, together with respiration by impedance plethysmography and end-tidal PCO2 by capnometry. In addition, measures of airway inflammation (fraction of exhaled nitric oxide), airway hyperreactivity (methacholine challenge), and reversibility of obstruction were obtained. Respiratory resistance at 5 and 20 Hz increased during unpleasant stimuli in asthma patients. This response was blocked by ipratropium bromide and was not substantially associated with asthma severity, airway inflammation, hyperreactivity and reversibility, or pattern of ventilation and PCO2. Under the placebo condition, changes in resistance during unpleasant films were positively correlated with patients' reports of psychological asthma triggers. In conclusion, airway constriction to unpleasant stimuli in asthma depends on an intact cholinergic pathway, is largely due to the central airways, and is not substantially associated with other indicators of airway pathology. Its link to the perceived psychological triggers in patients' daily lives suggests a physiological basis for emotion-induced asthma.

Airway cytokine responses to acute and repeated stress in a murine model of allergic asthma

Although stress is known to exacerbate asthma, the underlying mechanisms are unclear. Using a murine model of allergic asthma, Th1 (interleukin [IL]-2 and gamma-interferon [IFN-γ]) and Th2 (IL-4 and IL-5) airway cytokine responses and Th1:Th2 cytokine ratios to acute and repeated stress were examined in bronchoalveolar lavage fluid (BALF). Asthmatic mice showed significantly higher IL-4 level and Th2 predominance, compared with healthy mice. To acute stress, asthmatic mice significantly increased IL-4 but decreased IFN-γ levels favoring Th2 predominance, whereas healthy mice significantly decreased IL-4 level favoring Th1 predominance in BALF. To repeated stress, asthmatic mice significantly decreased IFN-γ, IL-4 and IL-5 levels overall favoring Th1 predominance, whereas healthy mice basically maintained the same response profile shown to acute stress. These findings suggest that a significant shift toward Th2 predominance in asthmatic mice under acute stress may be a mechanism underlying exacerbation of asthma.

Psychological distress and occupational asthma

PURPOSE OF REVIEW

To summarize recent findings on the psychological impact of occupational asthma, on the basis of a review of medical and psychological literature published between 1998 and 2008. For the purposes of this review, 'psychological impacts' are defined as the experience of psychological stress or distress, which refers to the experience of negative emotions (e.g., anxiety and sadness/depression). When severe and chronic, psychological distress may reach clinical levels and is referred to as a 'psychiatric disorder', which is a clinical diagnosis based on established diagnostic criteria.

RECENT FINDINGS

Only one original article assessing psychological impacts has been published in the past 10 years (in 2007). Levels of psychological distress (i.e., depression, anxiety, and cognitive dysfunction) were all in the clinical range, and rates of anxiety disorders and dysthymia (a chronic form of depression) affected approximately 35 and 23% of patients, respectively.

SUMMARY

The paucity of available literature indicates that the study of psychological factors associated with occupational asthma is still in its infancy. Though preliminary and in need of replication, the only published study to date suggests that patients with occupational asthma may be highly anxious and many are chronically depressed, a finding that is consistent with previous studies with nonoccupational asthmatics. The established link between psychological factors (e.g., depression and anxiety) and nonoccupational asthma suggests that future studies are desperately needed to more comprehensively assess the scope and severity of the psychological burden of this disease.

Negative affect, medication adherence, and asthma control in children

BACKGROUND

Negative affect including depression is known to be associated with asthma control, but whether and how it influences control in children with asthma is not understood.

OBJECTIVE

The objective of this investigation was to evaluate whether negative affect and medication nonadherence each predict decreased symptom control, and whether the relationship between negative affect and disease control is explained by children's adherence to asthma medications.

METHODS

Participants included 104 children 8 to 18 years old being treated with an inhaled corticosteroid delivered by metered-dose inhaler for asthma diagnosed by their health care providers. Children and parents independently rated asthma symptoms and completed questionnaires assessing sad and anxious affect. Electronic devices were attached to each participant's metered-dose inhaler to measure adherence. At study completion, records were collected to confirm reports of health events.

RESULTS

Both child and parent negative affect scores predicted symptom scores, whether reported by child or parent, and child negative affect scores predicted school absence because of asthma. In a lagged analysis taking into account time sequence, medication adherence predicted prednisone bursts but not subjective symptom scores. Nonadherence did not explain the relationship between negative affect and symptom scores, but parent negative affect predicted prednisone bursts even when controlling for level of adherence.

CONCLUSION

Although both negative affect and adherence were predictive of asthma control, the relationship of each to asthma control was distinctly different. Accuracy of symptom perception may be influenced by patient and parent affect characteristics.

Stress effects on lung function in asthma are mediated by changes in airway inflammation

OBJECTIVE

To examine the association of changes in current negative mood and long-term daily hassles with changes in lung function and airway inflammation in patients suffering from asthma and in healthy controls. Associations between psychological factors and asthma symptoms have been documented, but the relationship between airway inflammation and psychological factors has been largely unexplored.

METHOD

Data were analyzed from 46 asthma patients and 25 controls who completed questionnaires on current mood and daily hassles at two assessments 3 months apart. Lung function was measured by spirometry (forced expiratory volume in the first second (FEV(1))) and airway inflammation by the fraction of nitric oxide in exhaled air (FeNO). Regression analyses controlling for allergen load and air pollution (ozone) were calculated to study the association between changes in psychological factors and changes in lung function and airway inflammation, and to examine the mediational role of airway inflammation in the stress-lung function association.

RESULTS

In patients with asthma, increases in negative affect were associated with decreases in FEV(1) and increases in FeNO. For daily hassles, a reverse pattern of associations was found, with decreases in daily hassles linked to decreases in FEV(1) and increases in FeNO. Mediation analyses showed that FeNO was a significant mediator of the association of both negative affect and daily hassles with lung function changes. No significant associations were found for healthy controls.

CONCLUSION

Psychological variables are consistently associated with spirometric lung function and airway inflammation in asthma patients. For asthma patients, effects of acute negative affect must be distinguished from more chronic distress due to daily hassles.

The role of stress in asthma: insight from studies on the effect of acute and chronic stressors in models of airway inflammation

Asthma, a chronic inflammatory disease of the airways, is greatly influenced by psychosocial factors and stress. This review looks at clinical studies that have shown strong associations between psychological stress and asthma to identify potential mechanisms for these interactions. Furthermore, we review animal studies involving stress and airway inflammation or airway hyperresponsiveness, and discuss possible mechanisms of stress action in asthma. In conclusion, further research, both in humans and in animal models, into the mechanisms of stress-induced changes in asthma exacerbation are required to help better understand the complex makeup of asthma and assist in the development of therapies directed at the interplay between the nervous system and airway inflammation.

Emotions and respiratory function in asthma: a comparison of findings in everyday life and laboratory

OBJECTIVES

The present study examined the influence of emotions on the respiratory function in asthmatic and non-asthmatic individuals in everyday life and the relationship to emotion-induced respiratory changes in the laboratory.

METHODS

Affective states were induced in 10 asthmatic and 10 non-asthmatic participants by viewing affective picture series of either a pleasant, neutral, or unpleasant valence, while airway resistance (Raw) was measured with whole body plethysmography. Following this, individuals measured their mood, forced expiratory volume in the first second (FEV1), peak expiratory flow (PEF), physical activity, and medication use for 21 days with an electronic diary, which included a respiratory self-measurement device. Strong pleasant and unpleasant mood episodes were extracted from the diaries and compared with neutral affective states.

RESULTS

Asthmatic patients showed increases of Raw after unpleasant and pleasant emotional stimulation in the laboratory, which was only found after a pleasant stimulation in non-asthmatic participants. In everyday life, no group differences were obtained. Episodes of strong unpleasant mood states were associated with decreases in PEF, whereas in contrast to the laboratory assessment, pleasant mood was associated with increases in PEF. Results for FEV1 were comparable, but non-significant. Physical activity and medication use did not vary systematically between affective episodes. PEF showed no significant relationship with Raw.

CONCLUSIONS

Unpleasant mood is associated with decreased respiratory function in asthmatic patients in everyday life and in laboratory assessments, whereas effects of pleasant mood states are inconsistent. Pulmonary responses to laboratory-induced emotional conditions are not predictive of airways reactivity during daily life.

Implementation and interpretation of respiratory sinus arrhythmia measures in psychosomatic medicine: practice against better evidence?

Respiratory sinus arrhythmia (RSA) or high-frequency heart rate variability has been widely used as a noninvasive measure of cardiac vagal tone. However, their dependency on both respiration rate and tidal volume is largely ignored. Only a minority of studies published in Psychosomatic Medicine in recent years has implemented precautions for controlling respiration rate in RSA measures, and tidal volume effects were only rarely addressed. We discuss methodologic issues related to respiratory control methods and present data that demonstrate that both respiration rate and tidal volume contribute substantially to the within-individual RSA variance under conditions of variable breathing, with tidal volume contributing up to one third beyond respiration rate. Finally, we outline a respiratory control method for the time-domain index of RSA and review research pertaining to its reliability, validity, and experimental application.

Asthma self-efficacy, high frequency heart rate variability, and airflow obstruction during negative affect in daily life

BACKGROUND

Emotional stress has been considered an important asthma trigger for years, though the mechanisms by which stress may exacerbate asthma remain poorly understood. The stress-asthma morbidity association could occur through cognitive-behavioral pathways, such as decreased asthma self-efficacy and disorganized self-care, or through the more direct physiological effects of stress on autonomic (parasympathetic) nervous system activity. No study has examined how these two mechanisms may interact to contribute to greater airflow obstruction during emotional stress in daily life. This study investigated associations between peak expiratory flow rate (PEFR) and high frequency heart rate variability (HFHRV) during periods of negative affect and physical activity in daily life in patients with higher versus lower asthma self-efficacy scores.

METHODS

Fifty-three patients with mild to moderate asthma completed the Asthma Self-Efficacy Scale (ASES) and underwent a 15 h ambulatory assessment of daytime HFHRV and PEFR, while completing self-report diaries of their physical activities and affect.

RESULTS

In patients with lower asthma self-efficacy scores, increased levels of negative affect during daily life were associated with higher levels of HFHRV and decreased PEFR relative to patients with higher asthma self-efficacy scores. Increased levels of physical activity were associated with decreased levels of HFHRV irrespective of asthma self-efficacy scores.

CONCLUSIONS

Findings suggest that lower asthma self-efficacy may be associated with increased parasympathetic activity and airflow obstruction during periods of negative affect during daily life.

Airways, respiration, and respiratory sinus arrhythmia during picture viewing

Emotional stimuli can cause airway constriction; however, it is uncertain whether a dimensional or categorical model of emotion can better describe airway changes. Also, little is known about the affective modulation of respiration and vagal activity, which can influence airway tone. We studied changes in oscillatory resistance (Ros), respiration, and respiratory sinus arrhythmia (RSA) in asthmatics and controls during viewing of affective pictures eliciting anxiety, depression, disgust, happiness, contentment, erotic tension, or neutral affect. Ros, respiration, cardiac activity, and self-report were measured during picture presentations. Ros increased monotonically with picture unpleasantness mainly due to disgust pictures. RSA and respiratory timing parameters were particularly sensitive to erotic pictures. Differences between asthmatics and controls were minimal, suggesting that airway responses to unpleasant pictures are not specific to asthma.

Airflow and autonomic responses to stress and relaxation in asthma: the impact of stressor type

The impact of stress on respiratory airflow in asthmatics is unclear. Part of the uncertainty may spring from the different physiological effects of different stressors. Given their potential to elicit increases in parasympathetic vagal activity, stressful situations that present few opportunities for coping (passive coping stressors) may be particularly problematic for people with asthma. Thirty-one adult asthmatics participated in a protocol including a widely used passive coping stressor (the cold pressor test), an active coping stressor (mental arithmetic), an interview about an upsetting asthma-related incident (viewed as a potential passive coping stressor given the exposure to unpleasant memories), and progressive muscle relaxation. Repeated measurements of airflow (via peak expiratory flow), vagal tone (via heart rate variability), and other variables were obtained. The cold pressor test, asthma interview and progressive muscle relaxation produced significant decreases in airflow compared to the baseline period. The cold pressor test and progressive muscle relaxation produced significant, complementary increases in vagal tone. These results suggest that passive coping stressors and other stimuli (e.g., certain forms of relaxation) that elicit increased vagal tone may be associated with poorer asthma control, a view consistent with a significant negative correlation between the participant's mean vagal tone response to the tasks and score on a measure of asthma self-efficacy.

Probing the psychophysiology of the airways: physical activity, experienced emotion, and facially expressed emotion

This article reviews research on airway reactivity in health and asthma within a psychophysiological context, including the effects of physical activity, emotion induction, and manipulation of facial expression of emotion. Skeletal muscle activation leads to airway dilation, with vagal withdrawal being the most likely mechanism. Emotional arousal, in particular negative affect, leads to airway constriction, with evidence for a vagal pathway in depressive states and ventilatory contributions in positive affect. Laboratory-induced airway responses covary with reports of emotion-induced asthma and with lung function decline during negative mood in the field. Like physical activity, facial expression of emotion leads to airway dilation. However, these effects are small and less consistent in posed emotional expressions. The mechanisms of emotion-induced airway responses and potential benefits of emotional expression in asthma deserve further study.

Asthma exacerbations in children immediately following stressful life events: a Cox's hierarchical regression

BACKGROUND

A recent prospective study of children with asthma employing a within subject, over time analysis using dynamic logistic regression showed that severely negative life events significantly increased the risk of an acute exacerbation during the subsequent 6 week period. The timing of the maximum risk depended on the degree of chronic psychosocial stress also present. A hierarchical Cox regression analysis was undertaken to examine whether there were any immediate effects of negative life events in children without a background of high chronic stress.

METHODS

Sixty children with verified chronic asthma were followed prospectively for 18 months with continuous monitoring of asthma by daily symptom diaries and peak flow measurements, accompanied by repeated interview assessments of life events. The key outcome measures were asthma exacerbations and severely negative life events.

RESULTS

An immediate effect evident within the first 2 days following a severely negative life event increased the risk of a new asthma attack by a factor of 4.69, 95% confidence interval 2.33 to 9.44 (p<0.001) [corrected] In the period 3-10 days after a severe event there was no increased risk of an asthma attack (p = 0.5). In addition to the immediate effect, an increased risk of 1.81 (95% confidence interval 1.24 to 2.65) [corrected] was found 5-7 weeks after a severe event (p = 0.002). This is consistent with earlier findings. There was a statistically significant variation due to unobserved factors in the incidence of asthma attacks between the children.

CONCLUSION

The use of statistical methods capable of investigating short time lags showed that stressful life events significantly increase the risk of a new asthma attack immediately after the event; a more delayed increase in risk was also evident 5-7 weeks later.

Heart rate variability biofeedback increases baroreflex gain and peak expiratory flow

OBJECTIVE

We evaluated heart rate variability biofeedback as a method for increasing vagal baroreflex gain and improving pulmonary function among 54 healthy adults.

METHODS

We compared 10 sessions of biofeedback training with an uninstructed control. Cognitive and physiological effects were measured in four of the sessions.

RESULTS

We found acute increases in low-frequency and total spectrum heart rate variability, and in vagal baroreflex gain, correlated with slow breathing during biofeedback periods. Increased baseline baroreflex gain also occurred across sessions in the biofeedback group, independent of respiratory changes, and peak expiratory flow increased in this group, independently of cardiovascular changes. Biofeedback was accompanied by fewer adverse relaxation side effects than the control condition.

CONCLUSIONS

Heart rate variability biofeedback had strong long-term influences on resting baroreflex gain and pulmonary function. It should be examined as a method for treating cardiovascular and pulmonary diseases. Also, this study demonstrates neuroplasticity of the baroreflex.

The predictive value of the Toronto Alexithymia Scale among patients with asthma

OBJECTIVE

The present study examines how alexithymia, self-report of symptoms, and pulmonary function are related to each other among a sample of patients with asthma. The goal was to extend previous research showing that alexithymia may complicate treatment of asthma.

METHODS

Seventy-four participants with asthma completed the Toronto Alexithymia Scale (TAS), Asthma Symptom Checklist (ASC), Taylor Manifest Anxiety Scale (TMAS), and spirometry testing.

RESULTS

The "Difficulty identifying feelings" subscale (IDE) of the TAS was associated with increased report of emotional symptoms (panic-fear) as well as physical symptoms (fatigue) during the past week, but not pulmonary function on the day of testing. This relationship appeared to be influenced by trait anxiety. The "Difficulty communicating feelings" subscale (COM) was correlated with decreased pulmonary function, but not report of emotional or physical sensations experienced during the prior week. The "Externally oriented thinking" subscale (EOT) was not related to any of the dependent measures.

CONCLUSION

These data suggest that alexithymia may complicate optimal management of asthma and this relationship is best studied by examining the subscales of the TAS separately.

Airway response of healthy individuals to affective picture series

We studied the effects of viewing pictures in three series of homogeneous affects on respiratory resistance. Results from prior studies had been equivocal with respect to modulation of resistance by affective valence or arousal. Forty-two healthy participants viewed three series of affective slides preselected for global categories of positive, neutral and negative valence. Oscillatory resistance (R(os)), time, volume and flow parameters of respiration, cardiac interbeat-interval, respiratory sinus arrhythmia, and skin conductance were measured throughout the picture series, and individual pictures were rated in pleasure, arousal and interest. During the slide presentation, R(os) increased with decreasing picture valence. Other physiological parameters did not parallel these changes. R(os) changes were restricted to the expiratory portion of the breathing cycle, thus suggesting a contribution of upper airway sites to the response. It is concluded that R(os) is modulated by affective valence when pictures are selected in global categories of positive, neutral and negative affect. Observed airway responses are probably less informative with respect to affect-induced exacerbation in lower airway disease.

Psychological aspects of asthma

Asthma can be affected by stress, anxiety, sadness, and suggestion, as well as by environmental irritants or allergens, exercise, and infection. It also is associated with an elevated prevalence of anxiety and depressive disorders. Asthma and these psychological states and traits may mutually potentiate each other through direct psychophysiological mediation, nonadherence to medical regimen, exposure to asthma triggers, and inaccuracy of asthma symptom perception. Defensiveness is associated with inaccurate perception of airway resistance and stress-related bronchoconstriction. Asthma education programs that teach about the nature of the disease, medications, and trigger avoidance tend to reduce asthma morbidity. Other promising psychological interventions as adjuncts to medical treatment include training in symptom perception, stress management, hypnosis, yoga, and several biofeedback procedures.

Defensiveness and individual response stereotypy in asthma

OBJECTIVE

Previous literature has shown that the psychological trait of defensiveness is related to elevated sympathetic reactivity to stress and to several cardiac risk factors. The aim of this study was to examine whether these previous findings on defensiveness extend to an asthmatic population.

METHODS

Defensiveness was measured by the Marlowe-Crowne Social Desirability Scale using a quartile split: high (upper 25%) and low (bottom 75%). Twenty-two defensive and 66 nondefensive participants with asthma were exposed to laboratory tasks (initial baseline rest period, reaction time task, and a shop accident film).

RESULTS

During the tasks there was evidence of lower skin conductance levels and greater respiratory sinus arrhythmia amplitudes among defensive patients with asthma. After exposure to the tasks, defensive patients with asthma showed a decline on spirometry test measures compared with nondefensive asthmatic patients, who displayed an increase.

CONCLUSIONS

These data confirm individual response stereotypy and suggest that defensiveness may be characterized by sympathetic hypoarousal and parasympathetic hyperarousal among patients with asthma. Future studies are needed to determine whether defensiveness is a risk factor for stress-induced bronchoconstriction.

Relaxation therapy in adult asthma. Is there new evidence for its effectiveness?

Studies of relaxation training for adult asthma patients were reviewed for the period between 1980 and 2000. Six controlled and three uncontrolled studies were identified, employing a variety of methods, such as progressive relaxation, functional relaxation, autogenic training, or yoga. Most studies had low sample sizes and suffered from one or more methodological deficiencies, such as suboptimal data analysis, high dropout rates, problematic measurement procedures, or insufficient descriptions of methodology and results. Overall effects on parameters of lung function, symptoms, medication consumption, and health care use were generally negligible. Problems with the underlying rationale of relaxation therapy in asthma are discussed from a psychophysiological viewpoint. Examples are given of potential beneficial and detrimental effects of these techniques on lung function with respect to emotional processes, the musculoskeletal system, and ventilation as targets of a relaxation intervention. It remains to be demonstrated that relaxation training can significantly contribute to the standard treatment of asthma in adult patients.

Increases in total respiratory resistance during forehead temperature stimulation

We investigated the effects of forehead temperature stimulation on total respiratory resistance in healthy individuals. In two experiments involving a total of 38 participants we studied the time course and stability of the response at moderate temperature (20-23 degrees C). Small plastic bags filled with water were positioned on the forehead for a duration of 60 s. Oscillatory resistance (R(os)), heart period (HP), respiratory sinus arrhythmia (RSA), and ventilatory parameters were measured continuously. Experiment 1 showed similar phasic increases in R(os) during the first 20 s of stimulation with moderate (20-23 degrees C) as compared to cold (8-11 degrees C) temperature. Phasic increases by moderate temperature were replicated in Experiment 2 over five successive stimulation trials. Within-session stability of individual differences in response was only modest. Ventilatory adjustments did not facilitate the phasic R(os) increases. As increases were mainly due to the inspiratory component of R(os), a substantial contribution of upper airway artifacts was less likely. Increases in HP were the most pronounced responses to all stimulation conditions, while RSA did not increase significantly.

Stress and airway resistance in children with asthma

OBJECTIVE

The present study implements an experimental paradigm to examine airway reactivity to stress in children with asthma and controls.

METHOD

114 children with asthma and 30 controls (ages 9-15) participated. The protocol involved 5 min of baseline physiological measurements followed by a 5-min stressful task. Skin conductance (EDG), skin temperature, and heart rate were measured continuously. Airway resistance was measured at baseline and after the task.

RESULTS

110 children (76% of the sample) were significantly "stressed" as shown by physiological changes. Asthmatics and controls differed on overall airway resistance, F(1, 108)=12.3, P<.001. The entire sample demonstrated a trend toward increased airway resistance in response to stress, F(1,108)=3.1, P<. 08. A portion of asthmatics (22%) had increases of greater than 20% of baseline airway resistance. Changes in airway resistance in response to stress were unrelated to asthma severity, F(2,78)=2.0, ns.

CONCLUSION

Children with asthma and controls demonstrate variation in airway function in response to stress, although increases are likely more meaningful for children with asthma. Further research is needed to examine the mechanisms underlying this response.

Depression in Asthma: Prevalence and Clinical Implications

BACKGROUND: Asthma and depression are both common illnesses. Data suggest that the prevalence of asthma and asthma-related morbidity and mortality has increased in the past 2 decades. Asthma has long been considered an illness in which mood and emotions contribute to symptom exacerbation. Therefore, we reviewed the recent literature on depression in persons with asthma. DATA SOURCES: The MEDLINE (1966-1999) and PSYCHINFO (1967-1999) databases were used to find English-language articles on asthma and depression. Search terms included asthma, depression, dysthymia, and mood. DATA SYNTHESIS: This literature suggests depressive symptoms are more common in asthma patients than in the general population and perhaps even more common than in some other general medical conditions. Depression may be associated with asthma morbidity and mortality. Limited data suggest the older tricyclic antidepressants may improve both depression and asthma symptoms. However, no studies have examined the use of second-generation antidepressants in asthma patients. CONCLUSION: Depressive symptoms are common in asthma patients. However, the prevalence of depressive disorders in this population is not well determined. Future studies should focus on determining the prevalence of major depressive disorder in this population and the effect of antidepressants on mood and asthma symptoms.

Emotions and stress increase respiratory resistance in asthma

OBJECTIVES

Clinical reports suggest that various emotions and types of stress can precipitate asthmatic symptoms, but there is little experimental evidence to substantiate this claim. We studied the impact of different emotional states and stress on respiratory resistance in asthmatic and nonasthmatic individuals.

METHODS

Participants (24 asthmatic and 24 nonasthmatic patients) viewed short film sequences selected to induce anxiety, anger, depression, elation, happiness, contentment, or a neutral affective state and completed two stressful tasks, mental arithmetic to induce active coping efforts and viewing of medical slides to induce passive coping efforts. Oscillatory resistance, heart rate, blood pressure, baroreflex sensitivity, skin conductance level, respiration rate and volume, and self-reported affective state were measured throughout the session.

RESULTS

Uniform increases in oscillatory resistance were found in all emotional states compared with the neutral state and during mental arithmetic in both groups. Asthmatic patients showed stronger reactions to the medical slides than healthy control subjects, with significant increases in oscillatory resistance, blood pressure, skin conductance level, and minute volume, as well as higher levels of self-reported depression, arousal, and shortness of breath. Changes in oscillatory resistance were inconsistently correlated with other physiological indices.

CONCLUSIONS

Various emotional states and stress increase oscillatory resistance largely independently of concurrent increases in autonomic or ventilatory activity. The particular sensitivity of asthmatics to passive coping demand requires additional research.

Respiratory resistance during emotional stimulation: evidence for a nonspecific effect of experienced arousal?

We investigated the effects of phasic emotional stimuli on total respiratory resistance (TRR) in 16 nonasthmatic students. Six series of happy, neutral, and depressing affective pictures and self-referent Velten statements were presented. Each stimulus was presented for 12 s and subsequently imagined for 12 s. TRR was measured by forced oscillations throughout the stimulus series, together with ventilation, cardiac activity (including respiratory sinus arrhythmia), and facial EMGs (corrugator supercilii, orbicularis oculi, and masseter). In addition, self-reports of mood, pleasure and arousal were obtained. TRR was increased during happy and depressing stimuli compared to neutral stimuli, with stronger effects for the inspiratory component of TRR. Ventilatory parameters did not explain the changes observed in TRR. Discrimination of affective categories by facial EMG was weak. Although EMG masseter activity did not account for this result, an influence of the respiration measurement procedure on facial EMG cannot be ruled out. The TRR results are in accordance with clinical reports of asthmatic symptom aggravation due to positive or negative emotional arousal.