Differentiation between the sensory and affective aspects of histamine-induced bronchoconstriction in asthma

Severity and phenotypes of dyspnea in asthma: Impact of comorbidities

BACKGROUND

Dyspnea is a common but non-specific symptom of asthma, which in particular may be related to anxiety and hyperventilation syndrome, two frequent comorbidities of asthma.

METHODS

We conducted a prospective multicentric cohort study in dyspneic asthmatic adults. Dyspnea was assessed using the Multidimensional Dyspnea Profile questionnaire. We described the sensory (QS) and affective (A2) domains of dyspnea and investigated the effect of poor asthma control, hyperventilation and anxiety on each dimension at baseline and after 6 months.

RESULTS

We included 142 patients (65.5% women, age: 52 years). Dyspnea was severe and predominated on its sensory domain (median QS: 27/50; A2: 15/50). Uncontrolled asthma (ACQ≥1.5), hyperventilation symptoms (Nijmegen≥23) and anxiety (HAD-A≥10) were present in 75%, 45.7% and 39% of cases, respectively. Hyperventilation symptoms were associated with higher QS and A2 scores: QS at 28.4(10.7) vs. 21.7(12.8) (p = 0.001) and A2 at 24(14) vs. 11.3(11) (p < 0.001) in patients with vs. without hyperventilation symptoms. Anxiety was only associated with increased A2 (27(12.3) vs. 10.9(11), p < 0.001). At 6 months, QS and A2 decreased of 7 and 3 points, respectively, in relation with changes in ACQ-6 and Nijmegen scores as well as the HAD-A score for A2.

CONCLUSION

In breathless asthmatics, dyspnea is severe and worsened but differentially modulated by hyperventilation symptoms and anxiety. A multidimensional phenotyping of dyspnea in asthmatics could be useful to understand its origins and personalize treatment.

Effects of emotional contexts on respiratory attention task performance

Negative emotions have been found associated with high prevalence of respiratory disease and increased subjective feelings of dyspnea, while positive emotional stimulus has been suggested to alleviate dyspneic feelings. However, the extent to which different emotional contexts affect individuals' respiratory interoceptive attention was not clear. Therefore, the purpose of this study was to investigate the influences of emotional contexts on respiratory interoceptive accuracy, and the relationships between respiratory interoceptive accuracy and negative emotions as well as respiratory symptoms. Fifty-six healthy participants completed the self-reported questionnaires of depression, anxiety, and respiratory symptoms. During the experiment, the participants were instructed to watch one neutral and one positive affective picture series and mentally count the number of perceived occlusions (reported at the end of the trials). The Wilcoxon Signed-Rank test and Spearman's correlations were used to examine the effect of the emotional pictures and to explore the relationships between the level of emotional status or respiratory symptoms and respiratory interoceptive task performance. The significance level was set at p < 0.05. Our results did not show a significant difference in participants' occlusion counting task performance between the neutral and positive emotional context. However, Spearman's Rho correlation analysis revealed that depression level was negatively correlated with accuracy of the task performance in the neutral emotional context, and this relationship diminished in the positive emotional context. In summary, our study demonstrated that negative emotional status, especially depression, may lead to decreased respiratory interoceptive accuracy. Future studies are recommended to test the effect of positive emotional context on respiratory interoceptive task performance in individuals with clinical depression and anxiety.

Breathing control, brain, and bodily self-consciousness: Toward immersive digiceuticals to alleviate respiratory suffering

Breathing is peculiar among autonomic functions through several characteristics. It generates a very rich afferent traffic from an array of structures belonging to the respiratory system to various areas of the brain. It is intimately associated with bodily movements. It bears particular relationships with consciousness as its efferent motor control can be automatic or voluntary. In this review within the scope of "respiratory neurophysiology" or "respiratory neuroscience", we describe the physiological organisation of breathing control. We then review findings linking breathing and bodily self-consciousness through respiratory manipulations using virtual reality (VR). After discussing the currently admitted neurophysiological model for dyspnea, as well as a new Bayesian model applied to breathing control, we propose that visuo-respiratory paradigms -as developed in cognitive neuroscience- will foster insights into some of the basic mechanisms of the human respiratory system and will also lead to the development of immersive VR-based digital health tools (i.e. digiceuticals).

Dissociating breathlessness symptoms from mood in asthma

It is poorly understood why asthma symptoms are often discordant with objective medical tests. Differences in interoception (perception of internal bodily processes) may help explain symptom discordance, which may be further influenced by mood and attention. We explored inter-relationships between interoception, mood and attention in 63 individuals with asthma and 30 controls. Questionnaires, a breathing-related interoception task, two attention tasks, and standard clinical assessments were performed. Questionnaires were analysed using exploratory factor analysis, and linear regression examined relationships between measures. K-means clustering also defined asthma subgroups. Two concordant asthma subgroups (symptoms related appropriately to pathophysiology, normal mood) and one discordant subgroup (moderate symptoms, minor pathophysiology, low mood) were found. In all participants, negative mood correlated with decreased interoceptive ability and faster reaction times in an attention task. Our findings suggest that interpreting bodily sensations relates to mood, and this effect may be heightened in subgroups of individuals with asthma.

Subcortical gray matter volumes in asthma: associations with asthma duration, control, and anxiety

Asthma as a chronic inflammatory disease can be expected to affect central nervous system structures but little is known about subcortical structures in asthma and their potential association with illness-specific outcomes and anxiety. A total of 40 young adults (20 with asthma and 20 gender- and age-matched controls) underwent high-resolution T1-weighted MRI scan, viewed short distressing film clips, and filled in questionnaires about anxious and depressed mood, as well as asthma history, control, and catastrophizing thoughts about asthma, for those with asthma. The structural scans were processed in FSL's FIRST program to delineate subcortical structures of interest: amygdala, hippocampus, putamen, pallidum, caudate nucleus, nucleus accumbens, and thalamus. Findings showed no general reduction in subcortical gray matter volumes in asthma compared to controls. Asthma duration, asthma control, and catastrophizing of asthma and asthma attacks were negatively associated with volumes of putamen and pallidum, and to a weaker extent thalamus and amygdala, while controlling for gender, age, and corticosteroid inhaler use. In addition, stronger anxiety in response to distressing films was associated with lower volume of the pallidum, whereas general anxious and depressed mood was unrelated to subcortical structures. Thus, although there are no subcortical structural differences between young adults with asthma and healthy controls, longer asthma history, suboptimal management, and illness-related anxiety are reflected in lower gray matter volumes of subcortical structures, further emphasizing the importance of maintaining optimal asthma control.

Symptoms and perception of airway obstruction in asthmatic patients: Clinical implications for use of reliever medications

BACKGROUND

Asthma causes the unpleasant sensation of breathlessness (dyspnea) caused by airway obstruction. Patients with poor perception of airway obstruction are at risk of delay in seeking medical attention and undertreatment, which can lead to avoidable deaths. Conversely, those with heightened perception are at risk of overtreatment and iatrogenic adverse effects with reliever medications, anxiety, and unnecessary use of health care resources.

OBJECTIVE

We sought to review evidence about symptom misperception in asthmatic patients and how to identify and manage affected patients, particularly with regard to reliever medications.

METHODS

We conducted a systematic literature search for studies of perception of airway function in asthmatic patients. We searched the OVID (Medline and Medline [R] in process [PubMed]), Embase, and Adisearch/Odyssey databases, restricting our search to human studies published in English from 1990-2018, with no restrictions on age, sex, or racial origin.

RESULTS

We found that both underperception and overperception assessed during induced bronchoconstriction or bronchodilation or during changes in airway resistance were common across all age groups and that aging, disease severity, smoking, sex, ethnicity, psychologic factors, and medication are all associated with differences in perception. Importantly, airway inflammation was associated with impaired perception and a history of severe or near-fatal asthma. We also identified knowledge gaps, such as whether an individual patient's perception varies over time and the influence perception has on patients' use of reliever medication.

CONCLUSION

We found that abnormal perception of airway obstruction has important clinical implications for the management of patients with asthma.

Posttraumatic stress disorder following asthma attack: the role of agency beliefs in mediating psychiatric morbidity

BACKGROUND

The link between serious illness and subsequent posttraumatic stress disorder (PTSD) and psychiatric comorbidity has been established. In populations with asthma, however, few studies have investigated this link, or what psychological mechanisms mediate it. Healthcare guidance for chronic conditions, and PTSD literature, highlight "agency beliefs" as a direction for investigation.

AIMS

To determine the prevalence of PTSD following asthma attack, and investigate whether agency beliefs mediate PTSD and comorbid psychiatric symptoms in this population.

METHOD

We recruited 110 adults with asthma from online peer support forums. Participants completed the Asthma Symptom Checklist, PTSD Checklist, GHQ-28, General Self-Efficacy scale, and Multidimensional Health Locus of Control scale.

RESULTS

20% of our sample met criteria for PTSD. Regression results indicated that higher asthma severity significantly predicted PTSD and psychiatric co-morbidity. Lower self-efficacy significantly predicted PTSD symptoms while controlling for asthma severity, however Locus of Control (LoC) did not improve the model further. Self-efficacy, but not LoC, significantly partially mediated the effect of asthma severity on PTSD severity and psychiatric co-morbidity.

CONCLUSIONS

PTSD and other psychiatric symptoms in asthma populations are mediated in part by self-efficacy. Safeguarding and improving self-efficacy in this population is an important area for future research and intervention.

Dyspnea and emotional states in health and disease

Anxiety and depression can increase the intensity of dyspnea out of proportion to the impairment in cardiorespiratory function and may contribute to the degree of disability associated with dyspnea. The effect of anxiety/depression on the sensory and affective components of reported dyspnea in patients with respiratory disorders might be of particular importance in improving the accuracy of the diagnostic process. However, the exact cause-relationship between dyspnea and anxiety/depression are unclear. A multidimensional model of dyspnea subsuming sensory components (i.e. intensity and quality) and affective components has recently been proposed. Affective responses drive patients to seek treatment which can cause them to alter their lifestyle to avoid dyspnea. Brain imaging techniques help identify distinct cortical structures involved in processing the discrete components of dyspnea.

Predicting asthma treatment outcome at diagnosis: the role of symptom perception during a histamine challenge test

OBJECTIVE

In asthma, many treatment decisions are dependent upon patient perception/patient report of asthma symptoms. Discrepancies between patient perception of asthma symptoms and objective indicators of pathophysiology are widespread and can hinder asthma treatment. Early detection of problems in asthma symptom perception may be a first step to help these patients. We investigated the predictive value of symptom perception during a histamine challenge test (HCT) at asthma diagnosis for patient-rated outcome of asthma treatment 3 months later.

METHODS

In a prospective observational study, persons with asthma (N = 60) showing bronchial hyperresponsiveness in a HCT completed questions on asthma symptoms and negative affectivity (NA). The HCT was extended with an ambiguous situation suggesting asthma symptoms despite physiological recovery. Lung function (forced expiratory volume in 1 second (FEV(1))) and symptom ratings were measured during the test (after each histamine dosage), and we constructed several measures of asthma symptom perception based on FEV(1) and symptom ratings. Three months later, 30 participants completed questionnaires on asthma control and asthma-related quality of life.

RESULTS

Symptoms reported during HCT predicted worse asthma control and quality of life 3 months later. The prospective association between symptoms during HCT and asthma control remained significant when controlling for NA and baseline lung function. These effects were strongest for symptoms during ambiguous situations.

CONCLUSIONS

Higher symptom levels at the start of the HCT and during recovery may reflect a tendency to inaccurately perceive asthma symptoms in ambiguous situations. Assessing symptoms during diagnostic challenge tests can help predict problems with asthma treatment.

Dyspnoea and the brain

Chronic dyspnoea is a devastating symptom that debilitates millions of people worldwide. It causes a large burden on both patient and carer, and significant costs to society and health services. Treatment options are limited. Much effort has been directed at optimising lung function and improving exercise capacity, however, the brain mechanisms underlying dyspnoea perception have received less attention. In this review, we focus on cognitive and affective aspects of dyspnoea and discuss how novel neuroimaging methods can provide quantitative measures of these subjective sensations. We draw parallels with the more advanced field of chronic pain, and explain some of the challenges faced when imaging dyspnoea. To date, brain mechanisms of dyspnoea have been investigated in a handful of studies by a limited number of authors. These have found consistent activation in the insular cortex, the anterior cingulate cortex and the amygdala. Novel neuroimaging methods and an improved understanding of perceptual mechanisms underlying dyspnoea now position us to transform dyspnoea research. Future research should investigate how brain regions associated with dyspnoea interact, as well as accurately correlate this neuronal activation with reliable behavioural measures. A better understanding of the brain processes underlying dyspnoea perception will lead to new therapies that will improve quality of life for a very large group of patients.

Dyspnea-related anxiety: The Dutch version of the Breathlessness Beliefs Questionnaire

Dyspnea-related anxiety may lead to reduced quality of life and functional disability through fearful avoidance of dyspnea-evoking activity. We describe the validation of a generic - diagnosis-independent - instrument assessing dyspnea-related anxiety. A total of 187 patients with respiratory diseases completed the Breathlessness Beliefs Questionnaire (BBQ), a 17-item questionnaire adapted from the Tampa Scale for Kinesiophobia (TSK), a measure of how harmful pain patients think painful movement is and to what extent they think activity should be avoided. Measures of negative and positive affectivity (PANAS), anxiety and depression (HADS), functional status (PFSDQ), and health-related quality of life (CRDQ) were also completed. Principal component analysis and item-total correlations suggested a reliable (reduced) 11-item BBQ (Cronbach's alpha = .85) with two factors converging with the TSK factors: a 'somatic focus' factor assessing the harmfulness of dyspnea and the underlying pathology and an 'activity avoidance' factor assessing beliefs that activity should be avoided. Correlational analyses support the construct validity of the BBQ: higher scores on the BBQ are associated with reduced health-related quality of life and functional status. Associations between 'somatic focus' and negative affectivity and anxiety and between 'activity avoidance' and positive affectivity and depression further supported the validity of the BBQ and its subscales. The BBQ is a valid, short, and useful instrument to assess respiratory patients' beliefs about the harmfulness of their disease and physical activities. Further research is needed to document to what extent BBQ scores are related to daily life activities and symptoms.

The impact of affective states on the perception of dyspnea in patients with chronic obstructive pulmonary disease

Dyspnea is the cardinal symptom of chronic obstructive pulmonary disease (COPD). Affective states can profoundly impact upon the perception of dyspnea, but little is known about this relationship in patients with COPD. We, therefore, examined the impact of viewing positive versus negative affective picture series on perceived dyspnea during two cycle ergometer exercise tests (CEET) in 30 patients with COPD. Whereas cardiopulmonary measures indicated comparable exercise intensity during both CEETs, parallel viewing of negative affective pictures resulted in increased dyspnea ratings compared to positive affective pictures. Regression analyses showed that only during positive picture viewing increases in the affective unpleasantness of dyspnea, but not in the sensory intensity of dyspnea, during CEETs were predictive of greater dyspnea during everyday activities and reduced health-related quality of life. The results suggest that negative affective states increase perceived dyspnea in patients with COPD and underline the importance of targeting the affect-dyspnea-relationship in this patient group.

Repeated breathlessness experiences induced by hypercapnia: differential effects on intensity and unpleasantness

BACKGROUND

The present study investigated the effect of repeated hypercapnic challenges on the sensory (intensity [I]) and affective (unpleasantness [U]) dimensions of breathlessness.

METHODS

Three subsequent rebreathing trials (Read, 1968) were administered to healthy men and women (n = 39). The I and U of breathlessness were rated every 20 s during the baseline, rebreathing, and recovery phases. Breathing behavior (fractional end-tidal CO(2) [Fetco(2)] and minute ventilation [Ve]) was monitored continuously. Intraindividual linear regression slopes for Fetco(2) and Ve] were calculated and standardized, separately for both rating dimensions.

RESULTS

Both the absolute magnitude and the slope of the I of breathlessness were higher compared to U (p < 0.05). Across-trial habituation of the peak I and U of breathlessness occurred in both genders (p < 0.001), but habituation was larger for the U than for the I (p = 0.05).

CONCLUSIONS

The findings show that the sensory and affective dimensions of breathlessness can meaningfully be distinguished during hypercapnic challenges and that repeated exposures have different effects on both dimensions.

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.

Reduced perception of dyspnea and pain after right insular cortex lesions

RATIONALE

The perception of dyspnea and pain show many similarities. Initial imaging studies suggested an important role of the insular cortex for the perception of both sensations. However, little is known about the cortical processing of dyspnea.

OBJECTIVES

This study investigated the influence of lesions of the insular cortex on the perception of dyspnea and pain.

METHODS

Dyspnea was induced by resistive loaded breathing in four patients with right-hemispheric insular cortex lesions, as assessed with computer tomography or magnetic resonance imaging, and four matched healthy control subjects. Pain was induced by a cold-pressor test. Perceived intensity and unpleasantness of both sensations were rated on visual analog scales.

MEASUREMENTS AND MAIN RESULTS

In contrast to healthy control subjects, patients with lesions demonstrated reduced perceptual sensitivity for dyspnea, in particular for the unpleasantness of dyspnea (P < 0.05). This was paralleled by reduced sensitivity for pain in patients with lesions, as reflected by smaller ratings of intensity and unpleasantness, higher sensory pain-thresholds, and, in particular, higher affect-related pain tolerance times (P < 0.05).

CONCLUSIONS

The results suggest that lesions of the right insular cortex are associated with reduced sensitivity for the perception of dyspnea and pain, in particular for their perceived unpleasantness. This underlines the importance of the insular cortex for the perception of both sensations.

Differing reports of asthma symptoms in African Americans and Caucasians

OBJECTIVE

This pilot study explores the reported symptoms in African Americans and Caucasians with asthma.

METHODS

Asthma patients in an inner-city pulmonary clinic were given a brief questionnaire of asthma symptoms and the BORG scale, followed by spirometry.

RESULTS

African Americans were less likely to report nocturnal awakenings (67% vs. 100%; p = 0.037), complain of dyspnea (33% vs. 75%; p = 0.038), or experience chest pain (13% vs. 75%; p = 0.002) than Caucasians.

CONCLUSIONS

This is the first study to demonstrate that there are clinically significant differences in the reporting of asthma symptoms between African Americans and Caucasians.

Distractive Auditory Stimuli Reduce the Unpleasantness of Dyspnea During Exercise in Patients With COPD

BACKGROUND

Dyspnea is the primary symptom limiting exercise in patients with COPD. Recent research has demonstrated that psychological factors can substantially influence the perception of dyspnea, but little is known about the modulation of perceived intensity or unpleasantness of dyspnea by attentional distraction. Therefore, we examined the impact of distractive auditory stimuli on the perception of exercise-induced dyspnea and the affective state in patients with COPD during 6-min walking tests (6MWTs).

METHODS

Twenty patients with mild-to-severe COPD (mean FEV1, 55.9% predicted) underwent two 6MWTs. Under one exercise condition, distractive auditory stimuli were presented with headphones, while the other condition was performed without auditory distraction. Lung function (FEV1), heart rate (HR), pulse oximetric saturation (SpO2), perceived intensity of dyspnea (ie, visual analog scale for perceived intensity of dyspnea [VAS-I]), and perceived unpleasantness of dyspnea (visual analog scale for perceived unpleasantness of dyspnea [VAS-U]) were measured before and after exercise. In addition, the global level of dyspnea (Borg score), positive affectivity (PA), and negative affectivity were assessed after both conditions.

RESULTS

A similar exercise level during both conditions was confirmed by comparable results in FEV1, HR, SpO2, and distances walked. During auditory distraction, Borg scores and increases in VAS-U were smaller, while PA was higher compared to the nondistraction condition (p<0.05). VAS-I did not show differences across conditions.

CONCLUSIONS

Distractive auditory stimuli decrease the global level of exercise-induced dyspnea in patients with COPD by reducing the perceived unpleasantness of dyspnea and lead to an additional increase in PA. Auditory distraction might therefore serve as an intervention for the reduction of dyspnea during exercise in this patient group.