Defensiveness and perception of external inspiratory resistive loads in asthma

Respiratory modulation of intensity ratings and psychomotor response times to acoustic startle stimuli

Respiratory interoception may play an important role in the perception of respiratory symptoms in pulmonary diseases. As the respiratory cycle affects startle eye blink responses, startle modulation may be used to assess visceral-afferent signals from the respiratory system. To ascertain the potential impact of brainstem-relayed signals on cortical processes, we investigated whether this pre-attentive respiratory modulation of startle (RMS) effect is also reflected in the modulation of higher cognitive, evaluative processing of the startle stimulus. Twenty-nine healthy volunteers received 80 acoustic startle stimuli (100 or 105 dB(A); 50 ms), which were presented at end and mid inspiration and expiration, while performing a paced breathing task (0.25 Hz). Participants first responded to the startle probes by 'as fast as possible' button pushes and then rated the perceived intensity of the stimuli. Psychomotor response time was divided into 'reaction time' (RT; from stimulus onset to home button release; represents stimulus evaluation) and 'movement time' time (MT; from home button release to target button press). Intensity judgments were higher and RTs accelerated during mid expiration. No effect of respiratory cycle phase was found on eye blink responses and MTs. We conclude that respiratory cycle phase affects higher cognitive, attentional processing of startle stimuli.

Respiratory modulation of startle eye blink: a new approach to assess afferent signals from the respiratory system

Current approaches to assess interoception of respiratory functions cannot differentiate between the physiological basis of interoception, i.e. visceral-afferent signal processing, and the psychological process of attention focusing. Furthermore, they typically involve invasive procedures, e.g. induction of respiratory occlusions or the inhalation of CO₂-enriched air. The aim of this study was to test the capacity of startle methodology to reflect respiratory-related afferent signal processing, independent of invasive procedures. Forty-two healthy participants were tested in a spontaneous breathing and in a 0.25 Hz paced breathing condition. Acoustic startle noises of 105 dB(A) intensity (50 ms white noise) were presented with identical trial frequency at peak and on-going inspiration and expiration, based on a new pattern detection method, involving the online processing of the respiratory belt signal. The results show the highest startle magnitudes during on-going expiration compared with any other measurement points during the respiratory cycle, independent of whether breathing was spontaneous or paced. Afferent signals from slow adapting phasic pulmonary stretch receptors may be responsible for this effect. This study is the first to demonstrate startle modulation by respiration. These results offer the potential to apply startle methodology in the non-invasive testing of interoception-related aspects in respiratory psychophysiology.This article is part of the themed issue 'Interoception beyond homeostasis: affect, cognition and mental health'.

Repression and coping styles in asthmatic patients

The objectives of this study were to (a) determine prevalence of the dispositional repressive coping style as well as other situational coping styles in a sample of asthmatic patients and (b) to analyze the capacity of these styles to predict subsequent morbidity (emergency room visits or hospitalizations due to asthma) during a 12-month follow-up. A sample of 75 adult asthmatic patients was selected and information about sociodemographics, asthma severity, and patient's perception of illness severity was collected. Repressive coping style was defined by a combination of scores obtained on the Trait Anxiety Inventory and the Marlowe-Crowne Social Desirability Scale. Coping styles were assessed with the dispositional version of the Coping Orientation to Problems Experienced Inventory. Eighteen patients (24%) were classified as repressors. Repressor asthmatics obtained scores significantly lower on Emotion-Focused Coping compared to non-repressors (F ((1,72)) = 5.15, p = .026). Patients who perceived their asthma as severe reported to use Emotion-Focused Coping more than those who judged it as mild or moderate (F ((2,71)) = 4.83, p = .011). A higher use of Denial (an Emotion-Focused strategy of coping) explained 8% of variance of the frequency of emergency room visits during the 12-month follow-up. The prevalence of repressive coping style in the asthmatic population is similar to that registered in other populations of chronic patients, and it is also associated with the tendency to report a lower use of strategies traditionally considered as maladaptive. The use of Emotion-Focused Coping strategies seems to be related to a worse perception of the physical status, and among this group of strategies, Denial also could favor a poor clinical course in bronchial asthma.

Inaccurate perception of asthma symptoms: a cognitive-affective framework and implications for asthma treatment

Inaccurate perception of respiratory symptoms is often found in asthma patients. Typically, patients who inaccurately perceive asthma symptoms are divided into underperceivers and overperceivers. In this paper we point out that this division is problematic. We argue that little evidence exists for a trait-like stability of under- and overperception and that accuracy of respiratory symptom perception is highly variable within persons and strongly influenced by contextual information. Particularly, expectancy and affective cues appear to have a powerful influence on symptom accuracy. Based on these findings and incorporating recent work on associative learning, attention and mental representations in anxiety and symptom perception, we propose a cognitive-affective model of symptom perception in asthma. The model can act as a framework to understand both normal perception as well as under- and overperception of asthma symptoms and can guide the development of affect-related interventions to improve perceptual accuracy, asthma control and quality of life in asthma patients.

The multiple dimensions of dyspnea: review and hypotheses

Although dyspnea is a common and troubling symptom, our understanding of the neurophysiology of dyspnea is woefully incomplete. Most measurements of dyspnea treat it as a single entity. Although the multidimensional dyspnea concept has been mentioned for many decades, only recently has the concept been the subject of experimental tests. Emerging evidence has begun to favor the hypothesis that dyspnea comprises multiple dimensions or components that can be measured as different entities. Most recently, studies have begun to show that there is a separable 'affective dimension' (i.e. unpleasantness and emotional impact). Understanding of the multidimensional measurement of pain is far in advance of dyspnea, and has enabled progress in the neurophysiology of pain, including identification of separate neural structures subserving various elements of pain perception. We propose here a multidimensional model of dyspnea based on a state-of-the-art pain model, and review existing evidence in the light of this model.

The affective dimension of laboratory dyspnea: air hunger is more unpleasant than work/effort

RATIONALE

It is hypothesized that the affective dimension of dyspnea (unpleasantness, emotional response) is not strictly dependent on the intensity of dyspnea.

OBJECTIVES

We tested the hypothesis that the ratio of immediate unpleasantness (A(1)) to sensory intensity (SI) varies depending on the type of dyspnea.

METHODS

Twelve healthy subjects experienced three stimuli: stimulus 1: maximal eucapnic voluntary hyperpnea against inspiratory resistance, requiring 15 times the work of resting breathing; stimulus 2: Pet(CO(2)) 6.1 mm Hg above resting with ventilation restricted to less than spontaneous breathing; stimulus 3: Pet(CO(2)) 7.7 mm Hg above resting with ventilation further restricted. After each trial, subjects rated SI, A(1), and qualities of dyspnea on the Multidimensional Dyspnea Profile (MDP), a comprehensive instrument tested here for the first time.

MEASUREMENTS AND MAIN RESULTS

Stimulus 1 was always limited by subjects failing to meet a higher ventilation target; none signaled severe discomfort. This evoked work and effort sensations, with relatively low unpleasantness (mean A(1)/SI = 0.64). Stimulus 2, titrated to produce dyspnea ratings similar to those subjects gave during stimulus 1, evoked air hunger and produced significantly greater unpleasantness (mean A(1)/SI = 0.95). Stimulus 3, increased until air hunger was intolerable, evoked the highest intensity and unpleasantness ratings and high unpleasantness ratio (mean A(1)/SI = 1.09). When asked which they would prefer to repeat, all subjects chose stimulus 1.

CONCLUSIONS

(1) Maximal respiratory work is less unpleasant than moderately intense air hunger in this brief test; (2) unpleasantness of dyspnea can vary independently from perceived intensity, consistent with the prevailing model of pain; (3) separate dimensions of dyspnea can be measured with the MDP.

Dyspnea and symptom amplification in asthma

BACKGROUND

The severity of a patient's asthma and the intensity with which he describes his dyspnea do not correlate.

OBJECTIVES

There is an indirect relationship between airway function in asthma and the intensity of dyspnea; this relationship is found only when the measure of a patient's general tendency to exaggerate the intensity of any somatic symptom is considered simultaneously.

METHODS

Lung function, including spirometry (forced expiratory volume in 1 s, FEV(1)) and plethysmography (airway resistance, R(aw)), dyspnea (Borg scale score) and the tendency to exaggerate (the somatosensory amplification scale score, SSAS) have been quantified in 42 stable asthmatic patients.

RESULTS

There was no correlation between the Borg score and any spirometric or plethysmographic measure in these subjects. By contrast, there was a moderate correlation between the Borg score and the SSAS (r = 0.36, p = 0.03). However, when FEV(1) or R(aw) (abscissa) and Borg scores (ordinate) were converted to residuals, there was a moderate correlation between the residuals and the SSAS score (for FEV(1), r = 0.33 and p = 0.05; for R(aw), r = -0.36 and p = 0.03).

CONCLUSION

A physician may make a reasonable estimate of an asthmatic patient's lung function from the intensity of his complaint only if he - the physician - considers the patient's tendency to symptom amplify as well.

A test of the symptom amplification hypothesis in patients with asthma

The present study sought to measure the accuracy of symptom reporting in patients with asthma by calculating the difference between a subjective rating of illness severity and an objective test of lung function (forced expiratory volume in 1 second). At issue was the hypothesis that self-reported "symptom amplification" or sensory awareness accounts for differences in the accuracy of symptom reporting. Spirometric examination was performed, and psychological tests of symptom amplification, emotional distress, and neuroticism were administered. Participants consisted of 42 consecutive patients seeking medical treatment of asthma. The disparity between symptom perception (assessed by a Borg scale) and a corresponding measure of lung capacity allowed us to identify patients who overreported their symptoms (amplifiers) along with those who underreported them (minimizers). After controlling for the effects of sex and psychological distress, a self-report measure of symptom amplification explained 15% of the variability in reporting accuracy. Related constructs such as somatization and neuroticism could not explain differences in reporting ability.

Cortical substrates for the perception of dyspnea

Dyspnea is a common, unpleasant, and impairing symptom in various respiratory diseases and other diseases. Despite growing understanding of the multiple peripheral mechanisms giving rise to dyspnea, little is known about the cortical mechanisms underlying its perception. The results of neuroimaging studies have shown that distinct brain areas process the dyspneic sensation, among which the anterior insular seems to be the most important. Based on the findings of the first relevant neuroimaging studies, this review describes the cortical structures associated with the perception of dyspnea. Moreover, similarities to the perception of pain are discussed, and implications for future research are provided.

Advancing the science of perceptual accuracy in pediatric asthma and diabetes

OBJECTIVES

To review research on perceptual accuracy in pediatric asthma and diabetes and to provide recommendations for future research efforts and clinical applications of the construct in these populations.

METHODS

A literature search was conducted using Medline and PsychInfo databases as well as the bibliographies of relevant articles.

RESULTS

Children and adolescents with asthma or diabetes evidence considerable variability in perceptual accuracy and frequently make clinically relevant errors that have the potential to affect self-management behavior.

CONCLUSIONS

Recommendations for future research include studying distinct types of perceptual errors, empirically supporting the relationship between perceptual accuracy and relevant outcomes, identifying factors related to perceptual inaccuracy, and conducting longitudinal research and intervention studies. Recommendations for applying the construct in clinical practice include adopting an individualized approach to symptoms to guide patient education and management, identifying patients prone to making clinically relevant errors, and developing and implementing interventions to improve accuracy.

Negative affectivity and the influence of suggestion on asthma symptoms

OBJECTIVE

To investigate the effect of suggestion on subjective and objective asthma symptoms as a function of negative affectivity of the patients.

METHODS

Asthmatics (n=32) took puffs from three separate placebo inhalers, being described as an inert (practice) substance, a bronchoconstrictor, and a bronchodilator. Negative affectivity, social desirability, probability of medication-intake, intensity of asthma symptoms and total respiratory resistance were measured at onset. The latter three measures were repeated after each trial. Heart rate, end tidal PCO(2), and breathing behaviour were measured during each trial.

RESULTS

Asthmatics with high negative affectivity had overall more intense asthma symptoms. They also reported more airway obstruction after suggested bronchoconstriction and less after suggested bronchodilation, whereas persons with low negative affectivity did not show such variation. These effects were unrelated to social desirability. Respiratory symptoms correlated with the odds of medication intake. Neither negative affectivity nor suggestion influenced lung function and only breathing parameters under voluntary control changed as a function of suggestion.

CONCLUSION

Self-reported symptoms of asthmatics with high negative affectivity are more influenced by suggestion than those of patients with low negative affectivity.

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.

The perception of dyspnea in patients with mild asthma

BACKGROUND

Airway function, as assessed by standard spirometry, and the intensity of dyspnea reported by asthmatic patients correlate poorly.

OBJECTIVE

This study tests the following two hypotheses: (1) that measures of the tendency of a patient to somatize will reduce the variation in the report of dyspnea not explained by airway function; and (2) that plethysmography is a better tool with which to estimate the degree of dyspnea associated with asthma.

DESIGN

A prospective laboratory study carried out over one study session.

PARTICIPANTS

Forty asthmatic subjects who had withheld bronchodilator (BD) therapy overnight.

INTERVENTIONS

We performed spirometry, plethysmography, and an assessment of dyspnea (ie, modified Borg scale) on all subjects before and after they received BD therapy. Standard questionnaires pertaining to psychological state and trait were administered as well.

RESULTS

The change in specific airway conductance with BD therapy correlated with a decline in the Borg score (r = 0.47; p = 0.007). By contrast, neither spirographic measures nor measures of static lung volumes correlated. Correlation with the Borg scale score was not improved by adding indexes of either somatization or psychological state or trait.

CONCLUSION

The relief of dyspnea reported by patients with mild asthma after BD therapy is related to dilatation of the central airways.

Perception of induced bronchoconstriction in a community sample of adolescents

BACKGROUND

Poor perception of asthma symptoms has been cited as a risk factor for asthma death, yet there is no consensus as to the best way to characterize perception, and little is known about perception in normative samples. Hypoperceivers are of clinical interest because of risks of undertreatment; hyperperceivers are at risk for adverse iatrogenic effects caused by overtreatment.

OBJECTIVE

This study investigates perception of methacholine-induced bronchoconstriction in 175 adolescents.

METHODS

Breathlessness was rated after each inhalation by using the Borg scale. Perception groups were calculated on the basis of change from placebo Borg to high Borg scores (perception score at the highest methacholine dose). Subjects were called hypoperceivers if their Borg change score was greater than 1 SD below the mean for their FEV(1) group, hyperperceivers if their Borg change score was greater than 1 SD above the mean for their FEV(1) group, and accurate perceivers otherwise.

RESULTS

For subjects with an FEV(1) drop of less than 10%, accurate perceivers had a change in Borg score of 1.4 or less, and hyperperceivers had a change of greater than 1.4. For a drop in FEV(1) between 10% and 19%, hypoperceivers had a change in Borg score of less than 0.2, accurate perceivers had a change between 0.2 and 2.1, and hyperperceivers had a change of greater than 2.1. For those with an FEV(1) drop of 20% or greater, hypoperceivers had a Borg change of less than 0.2, accurate perceivers had a change between 0.2 and 2.6, and hyperperceivers had a change of greater than 2.6. No differences in age, sex, placebo Borg ratings, baseline pulmonary functions, PC(20) values, or psychologic variables were found among perception groups.

CONCLUSION

This study provides reference Borg values during methacholine challenge for 175 community adolescents.

Psychological issues in the treatment of asthmatic patients

Recently published research contends that anxiety and depression are more common in asthmatic patients than in the general population. Particular psychological profiles could even be a risk factor contributing to deaths caused by asthma. The purpose of our research was to evaluate the anxiety and depression level in a population of 80 asthmatic patients who were treated in our department, and to judge whether data collected on psychological profiles of these asthmatic patients can be of any significance when dealing with their pathology. The study consisted of 40 patients suffering from chronic viral hepatitis B or C, and 40 healthy subjects who served as a control group. Both sets of patients were homogeneous with regard to sex, age and education. All subjects were tested for anxiety and depression levels with the S.T.A.I. and Zung questionnaires. A structured questionnaire was employed to assess the daily approach to living with the disease only in asthmatic patients. The anxiety and depression levels were noticeably higher in asthmatic patients than in patients with chronic liver disease and healthy subjects. In particular, 34 asthmatic patients scored higher than the S.T.A.I. cut-off (40/80) and 27 attained the same results in the Zung questionnaire. Results from the asthmatic population and healthy subjects illustrated that women had a higher incidence of anxiety and depression compared to men, although no statistically significant relationship between sex and questionnaire results was apparent in patients with liver disease. In the year before assessment, hospitalization and emergency treatment due to asthmatic exacerbation was correlated in females with a high incidence of anxiety. Additionally, the asthmatic population's level of education is significantly related to the incidence of anxiety and depression. With higher education, incidence of depression and anxiety decreased. This result was not apparent in control groups. The results of our study were: (1) we confirmed that asthmatic pathology is associated with an increase in incidence of anxiety and depression, whose presence and seriousness should be taken into consideration in therapeutic programmes when dealing with a patient; (2) we indicated that a specific approach towards therapy is crucial when dealing with an asthmatic patient; (3) we suggested how important it is to identify categories of patients that require more care because of their psychological profile. These findings should provide for the optimal use of informational resources with important applications for educational programmes and the future treatment of the asthmatic population.

Expiratory time determined by individual anxiety levels in humans

We have previously found that individual anxiety levels influence respiratory rates in physical load and mental stress (Y. Masaoka and I. Homma. Int. J. Psychophysiol. 27: 153-159, 1997). On the basis of that study, in the present study we investigated the metabolic outputs during tests and analyzed the respiratory timing relationship between inspiration and expiration, taking into account individual anxiety levels. Disregarding anxiety levels, there were correlations between O2 consumption (VO2) and minute ventilation (VE) and between VO2 and tidal volume in the physical load test, but no correlations were observed in the noxious audio stimulation test. There was a volume-based increase in respiratory patterns in physical load; however, VE increased not only for the adjustment of metabolic needs but also for individual mental factors; anxiety participated in this increase. In the high-anxiety group, the VE-to-VO2 ratio, indicating ventilatory efficiency, increased in both tests. In the high-anxiety group, increases in respiratory rate contributed to a VE increase, and there were negative correlations between expiratory time and anxiety scores in both tests. In an awake state, the higher neural structure may dominantly affect the mechanism of respiratory rhythm generation. We focus on the relationship between expiratory time and anxiety and show diagrams of respiratory output, allowing for individual personality.