Are Current Theories of Panic Falsifiable?

Breathwork Interventions for Adults with Clinically Diagnosed Anxiety Disorders: A Scoping Review

Anxiety disorders are the most common group of mental disorders, but they are often underrecognized and undertreated in primary care. Dysfunctional breathing is a hallmark of anxiety disorders; however, mainstays of treatments do not tackle breathing in patients suffering anxiety. This scoping review aims to identify the nature and extent of the available research literature on the efficacy of breathwork interventions for adults with clinically diagnosed anxiety disorders using the DSM-5 classification system. Using the PRISMA extension for scoping reviews, a search of PubMed, Embase, and Scopus was conducted using terms related to anxiety disorders and breathwork interventions. Only clinical studies using breathwork (without the combination of other interventions) and performed on adult patients diagnosed with an anxiety disorder using the DSM-5 classification system were included. From 1081 articles identified across three databases, sixteen were included for the review. A range of breathwork interventions yielded significant improvements in anxiety symptoms in patients clinically diagnosed with anxiety disorders. The results around the role of hyperventilation in treatment of anxiety were contradictory in few of the examined studies. This evidence-based review supports the clinical utility of breathwork interventions and discusses effective treatment options and protocols that are feasible and accessible to patients suffering anxiety. Current gaps in knowledge for future research directions have also been identified.

Respiratory psychophysiology and COVID-19: A research agenda

After multiple waves of the COVID-19 pandemic, it has become clear that the impact of SARS-CoV-2 will carry on for years to come. Acutely infected patients show a broad range of disease severity, depending on virus variant, vaccination status, age and the presence of underlying medical and physical conditions, including obesity. Additionally, a large number of patients who have been infected with the virus present with post-COVID syndrome. In September 2020, the International Society for the Advancement of Respiratory Psychophysiology organized a virtual interest meeting on 'Respiratory research in the age of COVID-19', which aimed to discuss how research in respiratory psychophysiology could contribute to a better understanding of psychophysiological interactions in COVID-19. In the resulting current paper, we propose an interdisciplinary research agenda discussing selected research questions on acute and long-term neurobiological, physiological and psychological outcomes and mechanisms related to respiration and the airways in COVID-19, as well as research questions on comorbidity and potential treatment options, such as physical rehabilitation.

A network analysis of panic symptoms in relation to depression and anxiety sensitivity in patients with panic disorder

BACKGROUND

Panic disorder is an anxiety disorder presenting panic attacks as a defining feature, with cognitive and behavioral symptoms that are associated with the panic attacks. Recently, the use of network analysis is increasing to determine the symptoms and mutual reinforcing patterns that conceptualize a mental disorder. This study aimed to improve our understanding of panic disorder by estimating a network structure of its symptoms.

METHOD

Data from 257 patients diagnosed with panic disorder who visited the outpatient psychiatric clinic from 2018 to 2020 were collected. Panic attacks, cognitive and behavioral symptoms concerning the panic attacks, depression, and anxiety sensitivity dimensions such as fear of cardiovascular symptom, fear of publicly observable anxiety reaction, fear of respiratory symptom, and fear of cognitive dyscontrol were computed. Bootstrapping was applied to estimate the 95% confidence intervals for each edges.

RESULTS

The resulting network indicated fear of cognitive dyscontrol, impairment in social functioning, phobic avoidance of situations, and panic-focused anticipatory anxiety to be central symptoms in panic disorder. Interestingly, panic attacks and distress during panic did not emerge as central. Depression was strongly linked to fear of cognitive dyscontrol.

LIMITATIONS

The sample size limits network comparison tests between those with comorbid depression or agoraphobia. In addition, the cross-sectional design limits the opportunity to draw causal conclusions regarding the symptoms.

CONCLUSIONS

These results have implications in etiology of panic disorder and support the efficaciousness of Cognitive Behavioral Therapy. Future network analyses may employ longitudinal designs to investigate causal relationships between the symptoms.

Body Reprogramming: Reframing the Fibromyalgia narrative and providing an integrative therapeutic model

We propose a theory known as the Hyland model to help conceptualise Fibromyalgia within a complex adaptive control system. A fundamental assumption is that symptom generating mechanisms are causally connected, forming a network that has emergent properties. An illness narrative has been developed which has a ‘goodness of fit’ with the lived experience of those with Fibromyalgia. The theory guides management within the clinical setting and incorporates current evidence-based therapeutic strategies, within a multi-modal intervention described as ‘Body Reprogramming’. This intervention focuses on non-pharmacological and lifestyle-based considerations. The theoretical framework also helps explain why modest therapeutic effects are gained from current pharmacological options.

Psychotherapy: A World of Meanings

Despite a wealth of findings that psychotherapy is an effective psychological intervention, the principal mechanisms of psychotherapy change are still in debate. It has been suggested that all forms of psychotherapy provide a context which enables clients to transform the meaning of their experiences and symptoms in such a way as to help clients feel better, and function more adaptively. However, psychotherapy is not the only health care intervention that has been associated with "meaning": the reason why placebo has effects has also been proposed to be a "meaning response." Thus, it has been argued that the meaning of treatments has a central impact on beneficial (and by extension, negative) health-related responses. In light of the strong empirical support of a contextual understanding of psychotherapy and its effects, the aim of this conceptual analysis is to examine the role of meaning and its transformation in psychotherapy-in general-and within three different, commonly used psychotherapy modalities.

Panic Disorder Comorbidity with Medical Conditions and Treatment Implications

Panic disorder (PD) is unique among the anxiety disorders in that panic symptoms are primarily of a physical nature. Consequently, comorbidity with medical illness is significant. This review examines the association between PD and medical illness. We identify shared pathophysiological and psychological correlates and illustrate how physiological activation in panic sufferers underlies their symptom experience in the context of the fight-or-flight response and beyond a situation-specific response pattern. We then review evidence for bodily symptom perception accuracy in PD. Prevalence of comorbidity for PD and medical illness is presented, with a focus on respiratory and cardiovascular illness, irritable bowel syndrome, and diabetes, followed by an outline for potential pathways of a bidirectional association. We conclude by illustrating commonalities in mediating mechanistic pathways and moderating risk factors across medical illnesses, and we discuss implications for diagnosis and treatment of both types of conditions.

Low pre-treatment end-tidal CO2 predicts dropout from cognitive-behavioral therapy for anxiety and related disorders

Recent clinical trial research suggests that baseline low end-tidal CO₂ (ETCO₂, the biological marker of hyperventilation) may predict poorer response to cognitive-behavioral therapy (CBT) for anxiety-related disorders. The present study examined the predictive value of baseline ETCO₂ among patients treated for such disorders in a naturalistic clinical setting. Sixty-nine adults with a primary diagnosis of a DSM-5 anxiety disorder, obsessive-compulsive disorder, or posttraumatic stress disorder completed a 4-min assessment of resting ETCO₂, and respiration rate (the first minute was analyzed). Lower ETCO₂ was not associated with a diagnosis of panic disorder, and was associated with lower subjective distress ratings on certain measures. Baseline ETCO₂ significantly predicted treatment dropout: those meeting cutoff criteria for hypocapnia were more than twice as likely to drop out of treatment, and ETCO₂ significantly predicted dropout beyond other pre-treatment variables. Weekly measurement suggested that the lower-ETCO₂ patients who dropped out were not responding well to treatment prior to dropout. The present results, along with previous clinical trial data, suggest that lower pre-treatment ETCO₂ is a negative prognostic indicator for CBT for anxiety-related disorders. It is suggested that patients with lower ETCO₂ might benefit from additional intervention that targets respiratory abnormality.

Effects of therapeutic relationship, expectancy, and credibility in breathing therapies for anxiety

The authors investigated the effects of the quality of the therapeutic alliance, expectancy of improvement, and credibility of treatment on the outcome of two breathing therapies for anxiety and panic. Data were collected during a randomized clinical trial evaluating the efficacy of two theoretically opposing, end-tidal pCO2 feedback-assisted breathing therapies for patients experiencing anxiety attacks. In this study, five weekly individual breathing therapy sessions were administered for the patients who were experiencing anxiety attacks as symptoms of various anxiety disorders. The outcome of this trial indicated that regardless of the opposing breathing instructions (raise or lower pCO2) used in the two breathing therapies, patients in both treatment groups improved equally after treatment. Nonspecific factors rather than the different directions of pCO2 changes could have played a role in the improvement. Regression analyses showed that for both therapies patient-rated therapeutic alliance was predictive of improvement at the 1-month follow-up, and that patient-rated confidence that the therapy would produce improvement, an aspect of its credibility, accounted for almost half of the variance in improvement at the 6-month follow-up. Thus, two factors usually considered nonspecific were identified to be potent predictors of treatment outcome.

Taking an RDoC lens to the study of panic disorder: A commentary on Hamm et al. and other thoughts on RDoC

The Research Domain Criteria (RDoC) initiative put forth by the National Institute of Mental Health represents an exciting new framework in which to study psychopathology. The article by Hamm et al. (2016) is an interesting application of an "RDoC lens" toward a program of research on panic disorder. This commentary highlights the many strengths of the Hamm et al. (2016) study-most notably the article's application of a well-studied animal model of anxiety (Fanselow's, , threat imminence model) to humans, utilization of an interesting behavioral paradigm (as an analog for avoidance behaviors in panic disorder), and using RDoC to examine predictors of treatment response. This commentary also discusses several questions about RDoC that arise out of Hamm et al. For example, (a) How should participants be selected for RDoC studies? (b) Are RDoC constructs risk factors (and risk factors for what)? (c) Besides Hamm et al.'s, approach, how else can RDoC be used in treatment studies? In sum, Hamm et al. is a very good example of an RDoC study, and in this early phase of the initiative, more examples for how the approach plays out are needed.

Responses to voluntary hyperventilation in children with separation anxiety disorder: implications for the link to panic disorder

BACKGROUND

Biological theories on respiratory regulation have linked separation anxiety disorder (SAD) to panic disorder (PD). We tested if SAD children show similarly increased anxious and psychophysiological responding to voluntary hyperventilation and compromised recovery thereafter as has been observed in PD patients.

METHODS

Participants were 49 children (5-14 years old) with SAD, 21 clinical controls with other anxiety disorders, and 39 healthy controls. We assessed cardiac sympathetic and parasympathetic, respiratory (including pCO2), electrodermal, electromyographic, and self-report variables during baseline, paced hyperventilation, and recovery.

RESULTS

SAD children did not react with increased anxiety or panic symptoms and did not show signs of slowed recovery. However, during hyperventilation they exhibited elevated reactivity in respiratory variability, heart rate, and musculus corrugator supercilii activity indicating difficulty with respiratory regulation.

CONCLUSIONS

Reactions to hyperventilation are much less pronounced in children with SAD than in PD patients. SAD children showed voluntary breathing regulation deficits.

The weight of cognitions in panic: the link between misinterpretations and panic attacks

In cognitive theory it is hypothesized that panic attacks are provoked by catastrophic misinterpretations of bodily sensations. The aim of the present study was to investigate the ability of associated word pairs referring to catastrophic thinking (e.g. palpitations-heart attack) in producing panic attacks. Patients with PD (n = 20), patients with mixed anxiety disorders (n = 20), and a healthy control group (n = 30) participated in the present study. To enhance ecological validity we first conducted a stimulus validation experiment. Subsequently, nine suitable panic and neutral word pairs were presented in block to the participants. Anxiety levels were assessed before and after the presentation. PD patients were more anxious when reading these word pairs, compared to neutral word pairs. However, none of the participants experienced a panic attack upon reading the word pairs. From the present results it seems that catastrophic thinking is rather related to the anticipatory anxiety for panic attacks, but not necessarily with the occurrence of the panic attacks themselves.

Hypersensitivity to hypercapnia: definition/(s)

Empirical evidence indicates that panic disorder (PD) patients experience hypersensitivity to hypercapnia, a condition in which the blood level of carbon dioxide exceeds the normal value. The importance of this research line is substantial and indeed, hypercapnic hypersensitivity has been advanced as a possible endophenotype of panic. Definitions of "hypersensitivity," however, have varied. The purpose of this brief review is to delineate and critique different definitions of hypercapnic hypersensitivity. Several definitions - panic attack rate, panic symptoms including dyspnea, subjective anxiety, and respiratory disturbance - are explored. The review concludes that although no ideal definition has emerged, marked anxiety post-hypercapnia has substantial support as a putative trait marker of PD. The term "subjective hypersensitivity" (Coryell et al., 2001) is re-introduced to denote pronounced anxiety post-hypercapnia and recommended for use along with its previous definition: increased self-reported anxiety measured on a continuous visual analog scale, already widely in use. Due to the well-established link between panic and respiration, definitional candidates focusing on aberrant respiratory response - less investigated as trait markers of PD in high risk studies - warrant scrutiny as well. Several reasons why definitional clarity might be beneficial are presented, along with ideas for future research.

An evidence-based causal model of panic disorder

Recently, Fava and Morton (2009) described what they termed a 'causal model' of panic disorder (Causal modeling of panic disorder theories, Clinical Psychology Review, 29, 623-637). We examined several critical tenets of this proposed model, and offer significant revisions. Our revised causal model includes elements that have received empirical support, and exclude those with known limitations in explaining the etiology and treatment of panic disorder. Chief among these revisions are (1) an increased emphasis on anxiety sensitivity, (2) elimination of the more general psychodynamic conceptualization in favor of empirically supported findings regarding early attachment, and (3) placing biological and psychophysiological reactions as outcomes of false alarm threat, rather than causal mechanisms of panic.

Catastrophic misinterpretations as a predictor of symptom change during treatment for panic disorder

OBJECTIVE

Cognitive models of panic disorder suggest that change in catastrophic misinterpretations of bodily sensations will predict symptom reduction. To examine change processes, we used a repeated measures design to evaluate whether the trajectory of change in misinterpretations over the course of 12-week cognitive behavior therapy is related to the trajectory of change in a variety of panic-relevant outcomes.

METHOD

Participants had a primary diagnosis of panic disorder (N = 43; 70% female; mean age = 40.14 years). Race or ethnicity was reported as 91% Caucasian, 5% African American, 2.3% biracial, and 2.3% "other." Change in catastrophic misinterpretations (assessed with the Brief Body Sensations Interpretation Questionnaire; Clark et al., 1997) was used to predict a variety of treatment outcomes, including overall panic symptom severity (assessed with the Panic Disorder Severity Scale [PDSS]; Shear et al., 1997), panic attack frequency (assessed with the relevant PDSS item), panic-related distress/apprehension (assessed by a latent factor, including peak anxiety in response to a panic-relevant stressor-a straw breathing task), and avoidance (assessed by a latent factor, which included the Fear Questionnaire-Agoraphobic Avoidance subscale; Marks & Mathews, 1979).

RESULTS

Bivariate latent difference score modeling indicated that, as expected, change in catastrophic misinterpretations predicted subsequent reductions in overall symptom severity, panic attack frequency, distress/apprehension, and avoidance behavior. However, change in the various symptom domains was not typically a significant predictor of later interpretation change (except for the distress/apprehension factor).

CONCLUSIONS

These results provide considerable support for the cognitive model of panic and speak to the temporal sequence of change processes during therapy.

Respiratory and cognitive mediators of treatment change in panic disorder: evidence for intervention specificity

OBJECTIVE

There are numerous theories of panic disorder, each proposing a unique pathway of change leading to treatment success. However, little is known about whether improvements in proposed mediators are indeed associated with treatment outcomes and whether these mediators are specific to particular treatment modalities. Our purpose in this study was to analyze pathways of change in theoretically distinct interventions using longitudinal, moderated mediation analyses.

METHOD

Forty-one patients with panic disorder and agoraphobia were randomly assigned to receive 4 weeks of training aimed at altering either respiration (capnometry-assisted respiratory training) or panic-related cognitions (cognitive training). Changes in respiration (PCO₂, respiration rate), symptom appraisal, and a modality-nonspecific mediator (perceived control) were considered as possible mediators.

RESULTS

The reductions in panic symptom severity and panic-related cognitions and the improvements in perceived control were significant and comparable in both treatment groups. Capnometry-assisted respiratory training, but not cognitive training, led to corrections from initially hypocapnic to normocapnic levels. Moderated mediation and temporal analyses suggested that in capnometry-assisted respiratory training, PCO₂ unidirectionally mediated and preceded changes in symptom appraisal and perceived control and was unidirectionally associated with changes in panic symptom severity. In cognitive training, reductions in symptom appraisal were bidirectionally associated with perceived control and panic symptom severity. In addition, perceived control was bidirectionally related to panic symptom severity in both treatment conditions.

CONCLUSION

The findings suggest that reductions in panic symptom severity can be achieved through different pathways, consistent with the underlying models.

Temporal stability and coherence of anxiety, dyspnea, and physiological variables in panic disorder

Twenty-five panic disorder (PD) patients, 19 social phobics (SP), and 20 healthy controls (HC) sat quietly for 15 min, rating their anxiety and dyspnea every 30s while respiratory, cardiovascular, and electrodermal responses were recorded. No panic attacks were reported. For self-reported anxiety and dyspnea, within-subject variability over time was higher in PD than in SP or HC. In PD within-subject correlations across 30-s epochs were significant for (a) self-reported anxiety versus dyspnea, end-tidal pCO2, minute volume, duty cycle, skin conductance level, and interbeat interval, and for (b) dyspnea versus end-tidal pCO2, minute volume, tidal volume, and inspiratory flow rate. Several positive or negative correlations were greater in PD than in other groups. Thus in PD, experienced anxiety and dyspnea are temporally unstable but are correlated with each other and with fluctuations in respiratory and autonomic variables, even in the absence of panic attacks.

The psychophysiology of blood-injection-injury phobia: looking beyond the diphasic response paradigm

Blood-injection-injury (BII) phobia is an anxiety disorder that may be accompanied by vasovagal fainting during confrontation with the feared stimuli. The underlying pattern of autonomic regulation has been characterized as a diphasic response, with initial increases in heart rate and blood pressure that are typical of a fight-flight response, and subsequent drops in blood pressure and/or heart rate that may precipitate vasovagal fainting. Tensing skeletal muscles of the arms, legs, and trunk (applied tension) has been proposed as a technique to cope with this dysregulation. This review critically examines the empirical basis for the diphasic response and its treatment by applied tension in BII phobia. An alternative perspective on the psychophysiology of BII phobia and vasovagal fainting is offered by focusing on hypocapnia that leads to cerebral blood flow reductions, a perspective supported by research on neurocardiogenic and orthostatically-induced syncope. The evidence may indicate a role for respiration-focused coping techniques in BII phobia.

Hyperventilation in panic disorder and asthma: empirical evidence and clinical strategies

Sustained or spontaneous hyperventilation has been associated with a variety of physical symptoms and has been linked to a number of organic illnesses and mental disorders. Theories of panic disorder hold that hyperventilation either produces feared symptoms of hypocapnia or protects against feared suffocation symptoms of hypercapnia. Although the evidence for both theories is inconclusive, findings from observational, experimental, and therapeutic studies suggest an important role of low carbon dioxide (CO2) levels in this disorder. Similarly, hypocapnia and associated hyperpnia are linked to bronchoconstriction, symptom exacerbation, and lower quality of life in patients with asthma. Raising CO2 levels by means of therapeutic capnometry has proven beneficial effects in both disorders, and the reversing of hyperventilation has emerged as a potent mediator for reductions in panic symptom severity and treatment success.

Health anxiety and fear of fear in panic disorder and agoraphobia vs. social phobia: a prospective longitudinal study

BACKGROUND

This study is aimed to evaluate the role of two vulnerability factors, health anxiety and fear of fear, in the prediction of the onset of panic disorder/agoraphobia (PDA) relative to a comparison anxiety disorder.

METHODS

Young women, aged between 18 and 24 years, were investigated at baseline and, 17 months later, using the Anxiety Disorders Interview Schedule-Lifetime and measures of health anxiety and fear of bodily sensations (subscale disease phobia of the Whiteley Index, and total score of the Body Sensations Questionnaire). First, 22 women with current PDA were compared to 81 women with current social phobia and 1,283 controls. Second, 24 women with an incidence of PDA were compared to 60 women with an incidence of social phobia and 1,036 controls.

RESULTS

Multiple logistic regression analyses adjusted for history of physical diseases, somatic symptoms, and other psychological disorders revealed that (a) fear of bodily sensations was elevated for women with PDA vs. controls as well as women with social phobia, and (b) health anxiety (and history of physical diseases) was elevated in women who developed PDA vs. controls and vs. women who developed social phobia.

CONCLUSIONS

These results suggest that health anxiety, as well as history of physical diseases, may be specific vulnerability factors for the onset of PDA relative to social phobia. Whereas fear of bodily sensations was not found to be a risk factor for the onset of panic disorder/agoraphobia, it was a specific marker of existing PDA relative to social phobia.

Diversity of effective treatments of panic attacks: what do they have in common?

By comparing efficacious psychological therapies of different kinds, inferences about common effective treatment mechanisms can be made. We selected six therapies for review on the basis of the diversity of their theoretical rationales and evidence for superior efficacy: psychoanalytic psychotherapy, hypercapnic breathing training, hypocapnic breathing training, reprocessing with and without eye-movement desensitization, muscle relaxation, and cognitive behavior therapy. The likely common element of all these therapies is that they reduce the immediate expectancy of a panic attack, disrupting the vicious circle of fearing fear. Modifying expectation is usually regarded as a placebo mechanism in psychotherapy, but may be a specific treatment mechanism for panic. The fact that this is seldom the rationale communicated to the patient creates a moral dilemma: Is it ethical for therapists to mislead patients to help them? Pragmatic justification of a successful practice is a way out of this dilemma. Therapies should be evaluated that deal with expectations directly by promoting positive thinking or by fostering non-expectancy.

Change point analysis for longitudinal physiological data: detection of cardio-respiratory changes preceding panic attacks

Statistical methods for detecting changes in longitudinal time series of psychophysiological data are limited. ANOVA and mixed models are not designed to detect the existence, timing, or duration of unknown changes in such data. Change point (CP) analysis was developed to detect distinct changes in time series data. Preliminary reports using CP analysis for fMRI data are promising. Here, we illustrate the application of CP analysis for detecting discrete changes in ambulatory, peripheral physiological data leading up to naturally occurring panic attacks (PAs). The CP method was successful in detecting cardio-respiratory changes that preceded the onset of reported PAs. Furthermore, the changes were unique to the pre-PA period, and were not detected in matched non-PA control periods. The efficacy of our CP method was further validated by detecting patterns of change that were consistent with prominent respiratory theories of panic positing a relation between aberrant respiration and panic etiology.

Emotions beyond the laboratory: theoretical fundaments, study design, and analytic strategies for advanced ambulatory assessment

Questionnaire and interview assessment can provide reliable data on attitudes and self-perceptions on emotion, and experimental laboratory assessment can examine functional relations between stimuli and reactions under controlled conditions. On the other hand, ambulatory assessment is less constrained and provides naturalistic data on emotion in daily life, with the potential to (1) assure external validity of laboratory findings, (2) provide normative data on prevalence, quality and intensity of real-life emotion and associated processes, (3) characterize previously unidentified emotional phenomena, and (4) model real-life stimuli for representative laboratory research design. Technological innovations now allow for detailed ambulatory study of emotion across domains of subjective experience, overt behavior and physiology. However, methodological challenges abound that may compromise attempts to characterize biobehavioral aspects of emotion in the real world. For example, emotional effects can be masked by social engagement, mental and physical workloads, as well as by food intake and circadian and quasi-random variation in metabolic activity. The complexity of data streams and multitude of factors that influence them require a high degree of context specification for meaningful data interpretation. We consider possible solutions to typical and often overlooked issues related to ambulatory emotion research, including aspects of study design decisions, recording devices and channels, electronic diary implementation, and data analysis.

Do blood phobia patients hyperventilate during exposure by breathing faster, deeper, or both?

BACKGROUND

Recently we found that patients with blood-injection-injury (BII) phobia tend to hyperventilate when exposed to feared stimuli. Hyperventilation results from increases in minute ventilation above levels required by metabolic demand and can result from increases in either frequency or depth of breathing, or a combination of both.

METHOD

In order to determine which of these factors contributed most to hyperventilation in BII phobia we analyzed breathing patterns of BII phobia patients (N=12) and non-anxious controls (N=14), recorded with respiratory inductance plethysmography. Participants viewed ten film clips of either an emotionally positive, negative, or neutral quality, as well as surgery and asthma-relevant clips. During five film clips (one from each category) they also tensed their leg muscles.

RESULTS

Minute ventilation was markedly increased in blood phobia patients compared to other groups during surgery films. Also, tidal volume and irregularity of tidal volume showed strong increases, while respiration rate was not affected. Leg muscle tension increased ventilation in general but far below the extent brought about by hyperventilation in BII phobia. Patients who were breathing deeper during exposure reported stronger symptoms of dizziness, light-headedness and faintness. In general, patients showed a higher rate of spontaneous sighs throughout all film presentations, but not at baseline.

CONCLUSION

Thus, hyperventilation in blood phobia is produced by excessively deep and irregular breathing and may contribute to fainting responses. Behavioral interventions for BII phobia could benefit from attention to this aspect of dysfunctional breathing.

Psychophysiological reactions to two levels of voluntary hyperventilation in panic disorder

Panic disorder (PD) patients usually react with more self-reported distress to voluntary hyperventilation (HV) than do comparison groups. Less consistently PD patients manifest physiological differences such as more irregular breathing and slower normalization of lowered end-tidal pCO(2) after HV. To test whether physiological differences before, during, or after HV would be more evident after more intense HV, we designed a study in which 16 PD patients and 16 non-anxious controls hyperventilated for 3 min to 25 mmHg, and another 19 PD patients and another 17 controls to 20 mmHg. Patients reacted to HV to 20 mmHg but not to 25 mmHg with more self-reported symptoms than controls. However, at neither HV intensity were previous findings of irregular breathing and slow normalization of pCO(2) replicated. In general, differences between patients and controls in response to HV were in the cognitive-language rather than in the physiological realm.

An Internet-based investigation of the catastrophic misinterpretation model of panic disorder

The catastrophic misinterpretation (CM) model of panic disorder proposes that spontaneous panic attacks are the result of interpretation of harmless autonomic arousal as precursors to physical (e.g., heart attack) or psychological (e.g., insanity) emergency. Mixed research findings to date have provided equivocal support. The body sensations interpretation questionnaire-modified was administered via Internet to investigate core assumptions of the model among 30 people with panic disorder (PD), 28 with social anxiety disorder (SAD), and 30 non-anxious controls. The PD group gave more harm-related interpretations of ambiguous internal stimuli than both other groups, and this tendency to interpret ambiguous stimuli catastrophically was not also apparent for external/general events. Furthermore, people with PD rated harm and anxiety outcomes as more catastrophic than non-anxious controls. Results substantially support the CM model although a modification is proposed.

Hyperventilation symptoms are linked to a lower perceived health in asthma patients

BACKGROUND

Hyperventilation symptoms are among the sensations asthma patients tend to report during exacerbations of their disease. However, little is known about their importance for the patients' perceived well-being.

METHOD

We therefore studied the association of reported hyperventilation symptoms (Asthma Symptom Checklist) with perceived physical and mental health (36-item Short-form Health Survey) in a sample of primary care asthma patients (N = 190). We also studied the potential role of perceived control of asthma (Perceived Control of Asthma Questionnaire) in mediating any association between these variables.

RESULTS

In hierarchical multiple regression analyses controlling for demographics, asthma severity, and other asthma symptoms (obstruction, congestion, panic-fear, irritation, and fatigue), hyperventilation symptoms were significantly associated with both physical and mental health status. This association was partially mediated by perceived control of asthma.

CONCLUSION

It is possible that hypocapnia creates symptoms that asthma patients cannot control by using their antiasthmatic medication, thus compromising their perceived control over the management of their asthma, and consequently their perceived health. Behavioral interventions should address the problem of hyperventilation in asthma.

Muscle relaxation therapy for anxiety disorders: it works but how?

Muscle relaxation therapy (MRT) has continued to play an important role in the modern treatment of anxiety disorders. Abbreviations of the original progressive MRT protocol [Jacobson, E. (1938). Progressive relaxation (2nd ed.). Chicago: University of Chicago Press] have been found to be effective in panic disorder (PD) and generalized anxiety disorder (GAD). This review describes the most common MRT techniques, summarizes recent evidence of their effectiveness in treating anxiety, and explains their rationale and physiological basis. We conclude that although GAD and PD patients may exhibit elevated muscle tension and abnormal autonomic and respiratory measures during laboratory baseline assessments, the available evidence does not allow us to conclude that physiological activation decreases over the course of MRT in GAD and PD patients, even when patients report becoming less anxious. Better-designed studies will be required to identify the mechanisms of MRT and to advance clinical practice.

Acquired lightheadedness in response to odors after hyperventilation

OBJECTIVE

This study aimed to investigate whether lightheadedness in response to odors could be acquired through previous associations with hyperventilation-induced hypocapnia.

METHODS

Diluted ammonia and acetic acid served as conditional odor cues (CSs) in a differential associative learning paradigm. Hyperventilation-induced hypocapnia (unconditional stimulus [US]) was used to induce lightheadedness. In a training phase, participants (n = 28) performed three hypocapnic and three normocapnic overbreathing trials of 60 seconds each. One odor was consistently paired with the hypocapnic overbreathing (CS+); the other (control) odor was paired with normocapnic overbreathing (CS-). In the test phase, each odor was presented once during spontaneous breathing and once during normocapnic overventilation. Lightheadedness was assessed online during each breathing trial, which was followed by an extensive hyperventilation symptom checklist. Fractional end-tidal CO2, breathing frequency, and inspiratory volume were measured throughout the experiment.

RESULTS

In the test phase, participants experienced lightheadedness more quickly in response to the odor that had been paired with hypocapnic overbreathing compared with the control odor. They also scored higher on the symptom "feeling unreal."

CONCLUSION

Lightheadedness in response to odors can be acquired easily. The present results may help to elucidate the paradox that both avoidance and exposure to chemicals seem to be effective in reducing symptoms in idiopathic environmental illness.

Physiological markers for anxiety: Panic disorder and phobias

Physiological activation is a cardinal symptom of anxiety, although physiological measurement is still not used for psychiatric diagnosis. An ambulatory study of phobics who were afraid of highway driving showed a concordance between self-reported anxiety during driving, autonomic activation, hypocapnia, and sighing respiration. Patients with panic attacks do not exhibit autonomic activation when they are quietly sitting and not having panic attacks, but do have the same respiratory abnormalities as driving phobics, suggesting that these abnormalities could be a marker for panic disorder. Such abnormalities are compatible with both the false suffocation alarm (D. Klein) and hyperventilation (R. Ley) theories of panic. Hypocapnia, however, is often absent during full-blown panic attacks. Since activation functions as preparation for physical activity, it may not occur when a patient has learned that avoidance of fear by flight or fight is futile. We developed a capnometry feedback assisted breathing training therapy for panic disorder designed to reduce hyperventilation and making breathing regular. Without feedback, conventional therapeutic breathing instructions may actually increase hyperventilation by increasing dyspnea. Five weekly therapy sessions accompanied by daily home practice with a capnometer produced marked clinical improvement compared to changes in an untreated group. Improvement was sustained over a 12-month follow-up period. The therapist avoided any statements or procedures designed to alter cognitions. Improvement occurred regardless of whether patients initially reported mostly respiratory or non-respiratory symptoms during their attacks. There is evidence that modifying any of the three systems comprising a fear network can be therapeutic, as exemplified by cognitive therapy modifying thoughts, exposure therapy modifying avoidance, and breathing training procedures modifying pCO(2).

Voluntary hyperventilation in the treatment of panic disorder—functions of hyperventilation, their implications for breathing training, and recommendations for standardization

Hyperventilation has numerous theoretical and empirical links to anxiety and panic. Voluntary hyperventilation (VH) tests have been applied experimentally to understand psychological and physiological mechanisms that produce and maintain anxiety, and therapeutically in the treatment of anxiety disorders. From the theoretical perspective of hyperventilation theories of anxiety, VH is useful diagnostically to the clinician and educationally to the patient. From the theoretical perspective of cognitive-behavior therapy, VH is a way to expose patients with panic disorder to sensations associated with panic and to activate catastrophic cognitions that need restructuring. Here we review panic disorder treatment studies using breathing training that have included VH. We differentiate the roles of VH in diagnosis, education about symptoms, training of breathing strategies, interoceptive exposure, and outcome measurement--discussing methodological issues specific to these roles and VH test reliability and validity. We propose how VH procedures might be standardized in future studies.

Blood, Breath, Fears Redux, and Panic Attacks: Comment on Roth, Wilhelm, and Pettit (2005)

This article discusses the hyperventilation theory (HVT) of panic attacks (PAs) proposed by R. Ley in the context of criticisms raised by W. T. Roth, F. H. Wilhelm, and D. Pettit. Their interpretation of HVT is flawed by misunderstanding, misinterpretation, and oversimplification of the complex psychophysiological principles on which current HVT is based. Consequently, the "propositions" they derive are inappropriate. Further, Roth et al. disregarded/overlooked: (a) differences among types of PAs, (b) abundant empirical evidence that PA patients are distinguished by presence or absence of prominent respiratory symptoms (e.g., overbreathing), and (c) Ley's (1992b) classification of PAs based on 10 psychophysiological distinctions. The review by Roth et al. falls short of standards required to falsify HVT. Current HVT of PAs is tenable and testable.