Changes in respiration mediate changes in fear of bodily sensations in panic disorder

The duration discrimination respiratory task: A new test to measure respiratory interoceptive accuracy

Interoception, which refers to the perception of body's internal state, is implicated in emotional processes and psychopathological disorders. Over the last decades, different tools have been developed to measure interoceptive accuracy, or the ability to accurately perceive physiological signals. Most of these tools have focused on cardiac interoception, but respiratory interoception has been less investigated due to the more complex and less portable equipment required. In this study, we suggest a new duration discrimination respiratory (DDR) task that does not require complex equipment. Using an adaptive staircase procedure, this task aims to determine an individual's ability to detect exhalation longer than their resting reference duration. One hundred and twenty-three healthy subjects completed the DDR task, an interoceptive task of heart rate discrimination, and filled out questionnaires on interoceptive awareness (Multidimensional Assessment of Interoceptive Awareness), alexithymia (Toronto Alexithymia Scale [TAS]), affects (Positive and Negative Affect Scale [PANAS]), and anamnestic. Results demonstrated a good internal consistency (Cronbach's alpha = .93) of the DDR task. On average, subjects needed 99.22% (SD = 36.38) of their reference exhalation time in addition to reference exhalation to detect a prolonged exhalation. Higher self-reported fitness levels, not counting during the DDR task and lower difficulty in describing feelings (TAS subscale), predicted higher respiratory discrimination duration. In conclusion, this study demonstrates the utility of the DDR task as a valid measure of interoception.

Biofeedback Training to Increase P co2 in Asthma With Elevated Anxiety: A One-Stop Treatment of Both Conditions?

OBJECTIVE

Anxiety is highly prevalent in individuals with asthma. Asthma symptoms and medication can exacerbate anxiety, and vice versa. Unfortunately, treatments of comorbid anxiety and asthma are largely lacking. A problematic feature common to both conditions is hyperventilation. It adversely affects lung function and symptoms in asthma and anxiety. We examined whether a treatment to reduce hyperventilation, shown to improve asthma symptoms, also improves anxiety in asthma patients with high anxiety.

METHOD

One hundred twenty English- or Spanish-speaking adult patients with asthma were randomly assigned to either Capnometry-Assisted Respiratory Training (CART) to raise P co2 or feedback to slow respiratory rate (SLOW). Although anxiety was not an inclusion criterion, 21.7% met clinically relevant anxiety levels on the Hospital Anxiety and Depression Scale (HADS). Anxiety (HADS-A) and depression (HADS-D) scales, anxiety sensitivity (Anxiety Sensitivity Index [ASI]), and negative affect (Negative Affect Scale of the Positive Affect Negative Affect Schedule) were assessed at baseline, posttreatment, 1-month follow-up, and 6-month follow-up.

RESULTS

In this secondary analysis, asthma patients with high baseline anxiety showed greater reductions in ASI and PANAS-N in CART than in SLOW ( p values ≤ .005, Cohen d values ≥ 0.58). Furthermore, at 6-month follow-up, these patients also had lower ASI, PANAS-N, and HADS-D in CART than in SLOW ( p values ≤ .012, Cohen d values ≥ 0.54). Patients with low baseline anxiety did not have differential outcomes in CART than in SLOW.

CONCLUSIONS

For asthma patients with high anxiety, our brief training designed to raise P co2 resulted in significant and sustained reductions in anxiety sensitivity and negative affect compared with slow-breathing training. The findings lend support for P co2 as a potential physiological target for anxiety reduction in asthma.

TRIAL REGISTRATION

Clinicaltrials.gov Identifier: NCT00975273 .

Recent insights into respiratory modulation of brain activity offer new perspectives on cognition and emotion

Over the past six years, a rapidly growing number of studies have shown that respiration exerts a significant influence on sensory, affective, and cognitive processes. At the same time, an increasing amount of experimental evidence indicates that this influence occurs via modulation of neural oscillations and their synchronization between brain areas. In this article, we review the relevant findings and discuss whether they might inform our understanding of a variety of disorders that have been associated with abnormal patterns of respiration. We review literature on the role of respiration in chronic obstructive pulmonary disease (COPD), anxiety (panic attacks), and autism spectrum disorder (ASD), and we conclude that the new insights into respiratory modulation of neuronal activity may help understand the relationship between respiratory abnormalities and cognitive and affective deficits.

Acceptability of capnography-assisted respiratory therapy: a new mind-body intervention for COPD

Dyspnoea self-management is often suboptimal for patients with COPD. Many patients with COPD experience chronic dyspnoea as distressing and disabling, especially during physical activities. Breathing therapy is a behavioural intervention that targets reducing the distress and impact of dyspnoea on exertion in daily living. Using a qualitative design, we conducted interviews with 14 patients after they participated in a novel mind-body breathing therapy intervention adjunct, capnography-assisted respiratory therapy (CART), combined with outpatient pulmonary rehabilitation. Comprehensive CART consisted of patient-centred biofeedback, tailored breathing exercises, a home exercise programme and motivational interviewing counselling. We assessed participants' perceptions and reported experiences to gauge the acceptability of CART and refine CART based on feedback. Constant comparative analysis was used to identify commonalities and themes. We identified three main themes relating to the acceptability and reported benefits of CART: (1) self-regulating breathing; (2) impact on health; and (3) patient satisfaction. Our findings were used to refine and optimise CART (i.e. its intensity, timing and format) for COPD. By addressing dysfunctional breathing behaviours and dysregulated interoception, CART offers a promising new paradigm for relieving dyspnoea and related anxiety in patients with COPD.

Investigation of a Capnometry Guided Respiratory Intervention in the Treatment of Posttraumatic Stress Disorder

Evidence‐based treatments for posttraumatic stress disorder (PTSD), including psychotherapies and medications, have high dropout and nonresponse rates, suggesting that more acceptable and effective treatments for PTSD are needed. Capnometry Guided Respiratory Intervention (CGRI) is a digital therapeutic effective in panic disorder that measures and displays end-tidal carbon dioxide (EtCO₂) and respiratory rate (RR) in real-time within a structured breathing protocol and may have benefit in PTSD by moderating breathing and EtCO₂ levels. We conducted a single-arm study of a CGRI system, Freespira®, to treat symptoms of PTSD. Participants with PTSD (n = 55) were treated for four weeks with twice-daily, 17-min at-home CGRI sessions using a sensor and tablet with pre-loaded software. PTSD and associated symptoms were assessed at baseline, end-of treatment, 2-months and 6-months post-treatment. Primary efficacy outcome was 50% of participants having ≥ 6-point decrease in Clinician Administered PTSD Scale (CAPS-5) score at 2-month follow up. Tolerability, usability, safety, adherence and patient satisfaction were assessed. CGRI was well tolerated, with 88% [95% CI 74–96%] having ≥ 6-point decrease in CAPS-5 scores at 2-months post-treatment follow up. Mean CAPS-5 scores decreased from 49.5 [s.d. = 9.2] at baseline to 27.1 [s.d. = 17.8] at 2-months post-treatment follow up. Respiratory rate decreased and EtCO₂ levels increased. Associated mental and physical health symptoms also improved. This CGRI intervention was safe, acceptable, and well-tolerated in improving symptoms in this study in PTSD. Further study against an appropriate comparator is warranted.

Trial registration Clinicaltrials.gov NCT#03039231.

Further Exploration of Treatment Response in Latinos with Comorbid Asthma and Panic Disorder: A Brief Report of HRV and ETCO2 as Potential Mediators of Treatment Response

Heart rate variability (HRV) and end tidal CO2 (ETCO2) in relation to treatment response have not been studied in Latino populations or in comorbid asthma and panic disorder (PD). An extension of previously published research, the current study explored psychophysiological variables as possible mediators of treatment response. Latino treatment completers (N = 32) in the Bronx with asthma-PD received either Cognitive-Behavioral Psychophysiological Therapy (CBPT) or Music Relaxation Therapy (MRT). CBPT included HRV-biofeedback (HRVB); in-the-moment heart rate data to help an individual learn to influence his/her own heart rate. The sample was primarily female (93.8%) and Puerto Rican (81.25%). Treatment groups did not differ on demographics, except for less education in CBPT. The Panic Disorder Severity Scale (PDSS) and Asthma Control Questionnaire (ACQ) assessed changes in symptoms. HRV and ETCO2 were measured at four of eight therapy sessions. Baseline ETCO2 and changes in HRV from first to last of psychophysiology sessions were investigated as mediators of change on ACQ and PDSS. Mixed model analyses indicated in the CPBT group, changes in both asthma control and PD severity were not mediated by changes in HRV. In the CBPT and MRT groups combined, changes in PD severity were not mediated by baseline ETCO2. These findings may be due to the brevity of HRVB in CBPT, multiple treatment components, ETCO2 not directly targeted, and/or unique physiological pathways in Latinos with asthma-PD.

Habituation or Normalization? Experiential and Respiratory Recovery From Voluntary Hyperventilation in Treated Versus Untreated Patients With Panic Disorder

Psychophysiological theories postulate respiratory dysregulation as a mechanism contributing to panic disorder (PD). Additionally, symptomatic and respiratory recovery from voluntary hyperventilation (HVT-recovery) have been shown to lag in PD and it is unclear if HVT-recovery normalizes with treatment. Thirty-seven panic disorder patients were randomized to hypoventilation therapy (TX, n = 20) or waitlist control (WL, n = 17) (Meuret et al., 2008). In a secondary analysis, their HVT-recovery was analyzed at pre- and post-TX/WL, compared to 29 healthy controls (HC). HVT included three phases: 5-min baseline, 3-min hyperventilation, and 8-min recovery. HVT-elicited symptom severity and anxiety were rated following each phase, and end-tidal PCO₂ and respiratory rate (RR) were recorded throughout. Treatment, compared to WL, was highly effective in reducing PD pathology (d=2.21, Meuret et al., 2008). At pre-TX/WL, PD demonstrated delayed HVT-recovery PCO₂ and higher RR. Treated patients demonstrated normalization of HVT-recovery for PCO₂ and RR; however, improvements of HVT-recovery for symptom severity and anxiety did not differ between TX and WL. Results replicate pretreatment HVT respiratory recovery abnormalities in PD and further demonstrate normalization, comparable to HC, following successful treatment. The results provide support for respiratory dysregulation as a feature of PD and demonstrate the utility of HVT respiratory recovery as treatment outcome measure for respiration-based PD therapy.

Randomized clinical trial of capnometry-assisted respiratory training in veterans with posttraumatic stress disorder hyperarousal

OBJECTIVE

To investigate whether capnometry-assisted antihyperventilation respiratory training, successful in treating panic, and sleep hygiene instructions would reduce posttraumatic stress disorder (PTSD) hyperarousal symptoms in U.S. military veterans.

METHOD

We conducted a parallel, nonblinded clinical trial and randomized 80 veterans with PTSD hyperarousal into treatment or wait list. Primary treatment outcomes from baseline to 1st follow-up were analyzed using mixed modeling. Baseline physiological measures were compared between the PTSD hyperarousal group and a no-PTSD group (n = 68).

RESULTS

Baseline respiration rate but not partial-pressure of end-tidal carbon dioxide (PCO₂) was higher in the PTSD hyperarousal group than in the no-PTSD group during 3 min of quiet sitting, indicating no difference in baseline hyperventilation. There was no significant effect of the intervention on PTSD hyperarousal symptoms or hyperventilation compared to wait list, but treatment did lower respiratory rate.

CONCLUSION

This intervention did not reduce PTSD hyperarousal symptoms, perhaps due to differences between underlying mechanisms of PTSD hyperarousal and panic disorder or to differences between veteran and civilian populations. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Toward a personalized therapy for panic disorder: preliminary considerations from a work in progress

Although several treatment options for panic disorder (PD) are available, the best intervention for each individual patient remains uncertain and the use of a more personalized therapeutic approach in PD is required. In clinical practice, clinicians combine general scientific information and personal experience in the decision-making process to choose a tailored treatment for each patient. In this sense, clinicians already use a somehow personalized medicine strategy. However, the influence of their interpretative personal models may lead to bias related to personal convictions, not sufficiently grounded on scientific evidence. Hence, an effort to give some advice based on the science of personalized medicine could have positive effects on clinicians' decisions. Based on a narrative review of meta-analyses, systematic reviews, and experimental studies, we proposed a first-step attempt of evidence-based personalized therapy for PD. We focused on some phenomenological profiles, encompassing symptoms during/outside panic attacks, related patterns of physiological functions, and some aspects of physical health, which might be worth considering when developing treatment plans for patients with PD. We considered respiratory, cardiac, vestibular, and derealization/depersonalization profiles, with related implications for treatment. Given the extensiveness of the topic, we considered only medications and some somatic interventions. Our proposal should be considered neither exhaustive nor conclusive, as it is meant as a very preliminary step toward a future, robust evidence-based personalized therapy for PD. Clearly much more work is needed to achieve this goal, and recent technological advances, such as wearable devices, big data platforms, and the application of machine learning techniques, may help obtain reliable findings. We believe that combining the efforts of different research groups in this work in progress can lead to largely shared conclusions in the near future.

Mediators of Change in Capnometry Guided Respiratory Intervention for Panic Disorder

Capnometry guided respiratory interventions have shown promising results in the treatment of panic disorder, but mechanisms of change are not yet well-understood. The current study examined changes in end-tidal carbon dioxide (ETCO₂), anxiety sensitivity, and perceived control as mediators of panic symptom change. Sixty-nine adults with panic disorder received 4 weeks of respiratory training, and panic symptom severity and potential mediators were assessed at Pre-treatment, Mid-treatment, Post-treatment, 2-month follow-up, and 12-month follow-up. Multilevel mediation analyses showed that changes in perceived control significantly mediated changes in panic disorder severity and that for individuals who were hypocapnic at pre-treatment, ETCO₂ was a significant mediator of symptom outcome. Findings provide further evidence that changes in perceived control, and improvements in respiratory dysregulation for hypocapnic individuals specifically, underlie symptom improvement from capnometry guided respiratory intervention for panic disorder.

A Multisite Benchmarking Trial of Capnometry Guided Respiratory Intervention for Panic Disorder in Naturalistic Treatment Settings

Panic disorder (PD) is associated with hyperventilation. The efficacy of a brief respiratory feedback program for PD has been established. The aim of the present study was to expand these results by testing a similar program with more clinically representative patients and settings. Sixty-nine adults with PD received 4 weeks of Capnometry Guided Respiratory Intervention (CGRI) using Freespira, which provides feedback of end-tidal CO₂ (P_ETCO₂) and respiration rate (RR), in four non-academic clinical settings. This intervention is delivered via home use following initial training by a clinician and provides remote monitoring of client adherence and progress by the clinician. Outcomes were assessed post-treatment and at 2- and 12-month follow-up. CGRI was associated with an intent-to-treat response rate of 83% and a remission rate of 54%, and large decreases in panic severity. Similar decreases were found in functional impairment and in global illness severity. Gains were largely sustained at follow-up. P_ETCO₂ moved from the slightly hypocapnic range to the normocapnic range. Benchmarking analyses against a previously-published controlled trial showed very similar outcomes, despite substantial differences in sample composition and treatment settings. The present study confirms prior clinical results and lends further support to the viability of CGRI in the treatment of PD.

Hypoventilation Therapy Alleviates Panic by Repeated Induction of Dyspnea

BACKGROUND

Previous research has shown that hypoventilation therapy reduces panic symptoms in part by increasing basal partial pressure of carbon dioxide (PCO₂) levels. We tested an additional pathway by which hypoventilation therapy could exert its therapeutic effects: through repeated interoceptive exposure to sensations of dyspnea.

METHODS

A total of 35 patients with panic disorder were trained to perform exercises to raise their end-tidal PCO₂ levels using a portable capnometry device. Anxiety, dyspnea, end-tidal PCO₂, and respiratory rate were assessed during each exercise across 4 weeks of training. Mixed-model analysis examined whether within-exercise levels of dyspnea were predictive of reduction of panicogenic cognitions.

RESULTS

As expected, within-exercise anxiety and respiratory rate decreased over time. Unexpectedly, PCO₂ dropped significantly from the beginning to the end of exercise, with these drops becoming progressively smaller across weeks. Dyspnea increased and remained consistently above basal levels across weeks. As hypothesized, greater dyspnea was related to significantly lower panicogenic cognitions over time even after controlling for anxiety and PCO₂. Additional exploratory analyses showed that within-exercise increases in dyspnea were related to within-exercise increases in anxiety but were not related to within-exercise increases in PCO₂.

CONCLUSIONS

In support of the interoceptive exposure model, we found that greater dyspnea during hypoventilation exercises resulted in lower panicogenic cognitions even after the effect of PCO₂ was taken into account. The findings offer an additional important target in panic treatment.

Changes in Saving Cognitions Mediate Hoarding Symptom Change in Cognitive-Behavioral Therapy for Hoarding Disorder

Cognitive-behavioral therapy (CBT) is an empirically-supported treatment for hoarding disorder (HD). However, meta-analytic studies suggest that CBT is only modestly effective, and a significant number of individuals with HD remain symptomatic following treatment. To inform the development of more effective and targeted treatments, it will be important to clarify the mechanisms of treatment response in CBT for HD. To this end, the current study examined whether change in maladaptive saving beliefs mediated symptom change in CBT for HD. Sixty-two patients with primary HD completed measures of maladaptive saving cognitions and hoarding severity at pre-, mid-, and post-CBT. Results showed that change in saving cognitions mediated change in all three domains of HD symptoms (i.e., acquiring, difficulty discarding, and excessive clutter), suggesting that cognitive change may be a mechanism of treatment response in CBT. The findings indicate that cognitive change may have an impact on treatment outcomes, and are discussed in terms of cognitive-behavioral theory of HD and potential ways in which to enhance belief change in treatment.

Empirically supported psychological treatments and the Research Domain Criteria (RDoC)

BACKGROUND

The Research Domain Criteria (RDoC) has been developed as an alternative approach to studying psychiatric disorders. The RDoC constructs and units of analysis, from genes up through paradigms, are intended to describe a hierarchy of priority measurements. Several of these have been investigated in the context of empirically-supported treatments, as either moderators or mediators of outcome.

METHOD

This review considers the available research on the moderating and mediating role of genes, molecules, circuits and physiology in cognitive-behavior therapy (CBT) outcome studies for negative valence system conditions.

FINDINGS

Based on the review, research has aspired to identify candidate genes, molecules, circuits and physiological moderators or mediators of treatment, but no definitive tests have been conducted. Instead, several candidate variables have been found that deserve further investigation.

LIMITATIONS

The available research is based on diagnoses from the DSM, whereas the RDoC initiative endeavors to determine empirically valid taxonomic signs.

CONCLUSIONS

The results of this review are discussed in the joint context of developments in empirically-supported psychological therapy and the specific aims of the RDoC initiative, and conclude with recommendations for future research.

Psychological treatment of comorbid asthma and panic disorder in Latino adults: Results from a randomized controlled trial

Confusion between panic and asthma symptoms can result in serious self-management errors. A cognitive behavior psychophysiological therapy (CBPT) intervention was culturally adapted for Latinos consisting of CBT for panic disorder (PD), asthma education, differentiation between panic and asthma symptoms, and heart rate variability biofeedback. An RCT compared CBPT to music and relaxation therapy (MRT), which included listening to relaxing music and paced breathing at resting respiration rates. Fifty-three Latino (primarily Puerto Rican) adults with asthma and PD were randomly assigned to CBPT or MRT for 8 weekly sessions. Both groups showed improvements in PD severity, asthma control, and several other anxiety and asthma outcome measures from baseline to post-treatment and 3-month follow-up. CBPT showed an advantage over MRT for improvement in adherence to inhaled corticosteroids. Improvements in PD severity were mediated by anxiety sensitivity in CBPT and by depression in MRT, although earlier levels of these mediators did not predict subsequent improvements. Attrition was high (40%) in both groups, albeit comparable to CBT studies targeting anxiety in Latinos. Additional strategies are needed to improve retention in this high-risk population. Both CBPT and MRT may be efficacious interventions for comorbid asthma-PD, and CBPT may offer additional benefits for improving medication adherence.

Commentary on Kim et al., Effects of therapeutic relationship, expectancy, and credibility in breathing therapies for anxiety

Kim and colleagues (2015) explored influences on clinical outcomes related to nonspecific therapeutic factors, addressing the importance of client expectancy and development of the therapeutic alliance. In the process, however, the authors carry forward conclusions from their prior research on treatment of panic that two opposing breathing retraining protocols are equally effective. Neither the experimental design nor the sample size of the current or previous study warrants reaching those conclusions. This commentary examines the findings of the current and previous studies and points to consistent trends that suggest that breathing retraining of panic patients may be enhanced by protocols aimed at raising exhaled CO2.

Low baseline pCO2 predicts poorer outcome from behavioral treatment: evidence from a mixed anxiety disorders sample

Low levels of end-tidal partial pressure of carbon dioxide (pCO2)-the amount of carbon dioxide measured from expired air-are commonly found in individuals with anxiety disorders but have not been examined as predictors of outcome from anxiety treatment. The current study examined pre-treatment baseline pCO2 as a predictor of outcome from cognitive behavioral therapy (CBT) and acceptance and commitment therapy (ACT) for anxiety disorders. Sixty-one individuals with a Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) defined principal anxiety disorder diagnosis completed 12 sessions of either CBT or ACT. Baseline pCO2 was measured prior to entering treatment. Self-reported anxiety symptoms and quality of life were assessed at pre-treatment, post-treatment, and 6- and 12-month follow-up from baseline. Low baseline pCO2 was associated with higher anxiety symptoms and lower quality of life across follow-up timepoints, above and beyond baseline symptom severity. These results suggest that low baseline pCO2 predicts poorer outcome from CBT and ACT for anxiety and may warrant treatment that directly addresses respiratory dysregulation.

Phosphate levels as a possible state marker in panic disorder: preliminary study of a feasible laboratory measure for routine clinical practice

OBJECTIVE

Low serum phosphate level is considered one of the metabolic adaptations to the respiratory alkalosis induced by hyperventilation associated with panic disorder. The aim of this study was to assess phosphatemia as a possible state marker for panic disorder.

METHODS

Sixteen panic disorder patients underwent clinical assessment with a semi-structured interview, a set of rating scales and the self-rated State and Trait Anxiety Inventory (STAI), as well as extraction of venous blood samples at baseline and after 12 weeks of pharmacological treatment. Ten healthy volunteers of similar sex, age and educational level filled out the STAI and gave blood samples at baseline and 12 weeks later.

RESULTS

The median (25th-75th percentiles) of phosphate levels (mg/dl) was 2.68 (2.22-3.18) among patients and 4.13 (3.74-4.70) among healthy volunteers respectively (P < 0.001). Seven (44%) patients and no healthy volunteers presented low serum phosphate (<2.50 mg/dl) at baseline; this patient abnormality was corrected in all cases after successful treatment. At baseline, the age-adjusted correlation between phosphate levels and state-anxiety was -0.66 (P < 0.001) among all 26 participants and -0.51 (P = 0.05) among the 16 panic disorder patients.

CONCLUSIONS

Measurement of phosphate levels could be easily introduced into clinical practice as a possible marker for chronic hyperventilation in panic disorder, although further investigations with larger sample sizes are necessary to characterize panic disorder patients with low versus normal phosphate levels.

Breathing Retraining for Individuals Who Fear Respiratory Sensations: Examination of Safety Behavior and Coping Aid Hypotheses

Cognitive behavioral theorists have suggested that breathing retraining may be used as a safety behavior. Safety behaviors are acts aimed at preventing or minimizing feared catastrophe and may maintain pathologic anxiety by hindering resolution of maladaptive cognitive processes. An opposing position is that breathing retraining is an effective coping aid. This study examined the safety behavior and coping aid hypotheses as they apply to breathing retraining. Individuals high in fear of respiratory sensations were randomly assigned to a psychoeducation control condition (EDU; n = 27) or a psychoeducation plus breathing retraining condition (EDU+BR; n = 30). As compared to psychoeducation alone, the addition of breathing retraining neither limited improvement of cognitive processes (e.g., anxiety sensitivity) nor added to the gains observed on measures of coping (e.g., perceived control). The findings are evaluated in light of the available literature regarding breathing retraining and the safety behavior and coping aid hypotheses.

A psychophysiological investigation of threat and reward sensitivity in individuals with panic disorder and/or major depressive disorder

Heightened sensitivity to threat and reduced sensitivity to reward are potential mechanisms of dysfunction in anxiety and depressive disorders, respectively. However, few studies have simultaneously examined whether these mechanisms are unique or common to these disorders. In this study, sensitivity to predictable and unpredictable threat (measured by startle response during threat anticipation) and sensitivity to reward (measured by frontal electroencephalographic [EEG] asymmetry during reward anticipation) were assessed in 4 groups (N = 191): those with (1) panic disorder (PD) without a lifetime history of depression, (2) major depression (MDD) without a lifetime history of an anxiety disorder, (3) comorbid PD and MDD, and (4) controls. General distress/negative temperament (NT) was also assessed via self-report. Results indicated that PD (with or without comorbid MDD) was uniquely associated with heightened startle to predictable and unpredictable threat, and MDD (with or without comorbid PD) was uniquely associated with reduced frontal EEG asymmetry. Both psychophysiological measures of threat and reward sensitivity were stable on retest approximately 9 days later in a subsample of participants. Whereas the comorbid group did not respond differently on the tasks relative to the PD-only and MDD-only groups, they did report greater NT than these 2 groups (which did not differ from each other). Results suggest that heightened sensitivity to threat and reduced sensitivity to reward may be specific components of PD and MDD, respectively. In addition, relative to noncomorbid depression and PD, comorbid MDD and PD may be characterized by heightened NT, but not abnormal levels of these "specific" components.

Hypoventilation training for asthma: a case illustration

Hyperventilation-induced hypocapnia is common among asthma patients. This case study illustrates both methodology and results from a patient undergoing training in capnometry-assisted respiratory training (CART). CART is a 4-week training aimed at normalizing basal and acute levels of end-tidal carbon dioxide (PCO(2)) using a portable capnometer. In the presented case, basal levels of PCO(2) increased from hypocapnic to normocapnic range over the course of treatment. Improvements were accompanied by improvements in lung function and reductions in diurnal lung function variability. Improvements remained stable throughout follow-up.

Coping skills and exposure therapy in panic disorder and agoraphobia: latest advances and future directions

Although cognitive-behavioral treatments for panic disorder have demonstrated efficacy, a considerable number of patients terminate treatment prematurely or remain symtpomatic. Cognitive and biobehavioral coping skills are taught to improve exposure therapy outcomes but evidence for an additive effect is largely lacking. Current methodologies used to study the augmenting effects of coping skills test the degree to which the delivery of coping skills enhances outcomes. However, they do not assess the degree to which acquisition of coping skills and their application during exposure therapy augment outcomes. We examine the extant evidence on the role of traditional coping skills in augmenting exposure for panic disorder, discuss the limitations of existing research, and offer recommendations for methodological advances.

Does fear reactivity during exposure predict panic symptom reduction?

OBJECTIVE

Fear reactivity during exposure is a commonly used indicator of learning and overall therapy outcome. The objective of this study was to assess the predictive value of fear reactivity during exposure using multimodal indicators and an advanced analytical design. We also investigated the degree to which treatment condition (cognitive training vs. respiratory skill training) moderated fear reactivity and therapeutic outcome.

METHOD

Thirty-four patients with panic disorder and agoraphobia completed a total of 123 in-vivo exposure sessions, comprising 3 weekly sessions and a 4th session 2 months following therapy completion. Sessions varied in length and phobic stimuli. Cardiorespiratory physiology (heart rate, carbon dioxide partial pressure [PCO2], respiration rate) and experiential symptoms (panic symptoms and anxiety) were assessed repeatedly throughout exposure sessions, in addition to weekly assessments of panic cognitions, avoidance, and functioning.

RESULTS

Panic symptomatology decreased substantially in both treatment conditions during therapy and follow-up. Significant cardiorespiratory and experiential reactivity was observed during all exposures, characterized by activation followed by reduction. Greater within-session activation of anxiety and panic symptoms was inversely related to improvement in panic symptoms severity, but neither physiological activation nor within- or between-session reduction of either physiological or experiential variables was predictive of outcome. No moderating effects of treatment condition were found.

CONCLUSIONS

Fear activation and reduction during exposure are weak predictors of corrective learning and fear extinction. Clinical implications for exposure therapy and directions for future research are discussed.

Medically unexplained dyspnea: partly moderated by dysfunctional (thoracic dominant) breathing pattern

BACKGROUND

Dysfunctional breathing (DB) may contribute to disproportionate dyspnea and other medically unexplained symptoms. The extent of dysfunctional breathing is often evaluated using the Nijmegen Questionnaire (NQ) or by the presence of abnormal breathing patterns. The NQ was originally devised to evaluate one form of dysfunctional breathing - hyperventilation syndrome. However, the symptoms identified by the NQ are not primarily due to hypocapnia and may be due to other causes including breathing pattern dysfunction.

OBJECTIVES

The relationships between breathing pattern abnormalities and the various categories of NQ symptoms including respiratory or dyspnea symptoms have not been investigated. This study investigates these relationships.

METHOD

62 patients with medically unexplained complaints, that seemed to be associated with tension and breathing dysfunction, were referred, or self-referred, for breathing and relaxation therapy. Dysfunctional breathing symptoms and breathing patterns were assessed at the beginning and end of treatments using the NQ for assessment of DB symptoms, and the Manual Assessment of Respiratory Motion (MARM) to quantify the extent of thoracic dominant breathing. Subscales for the NQ were created in 4 categories, tension, central neurovascular, peripheral neurovascular and dyspnea. Relationships between the NQ (sum scores and subscales) and the MARM were explored.

RESULTS

Mean NQ scores were elevated and mean MARM values for thoracic breathing were also elevated. There was a small correlation pre-treatment between MARM and NQ (r=0.26, p<0.05), but classification of subjects as normal/abnormal on both measurements agreed in 74% (p < 0.001) of patients. From the sub scores of NQ only the respiratory or 'dyspnea' items correlated with the MARM values. Dyspnea was only elevated for subjects with abnormal MARM. After treatment, both MARM and NQ returned to normal values (p< 0.0001). Changes in NQ were largest for subjects with abnormal MARM pre-treatment. There was a large interaction between the change in the NQ sub score dyspnea and initial MARM values. (p<0.001).

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.

Catastrophic Appraisal and Perceived Control as Moderators of Treatment Response in Panic Disorder

The purpose of this study was to examine the moderating effects of cognitive risk factors in two mechanistically-distinct interventions. Forty-one patients with panic disorder and agoraphobia were randomly assigned to receive training aimed at altering respiration (Capnometry-assisted respiratory training, CART) or symptom appraisal (cognitive skill training, CT). Using a mixed effects regression model, we assessed whether reductions in panic symptom severity (PDSS) were moderated by the variables of interest. While improvement in PDSS did not differ among treatment modalities, moderating effects emerged. Individuals with greater initial levels of misappraisal showed smaller reduction in PDSS when receiving CT, but larger reduction when receiving CART. Greater lack of perceived control was predictive of worse outcome in CART, but better outcome in CT. Better homework compliance was related to greater reductions in PDSS irrespective of condition. The findings illustrate the complexity of moderating influences within and between distinct interventions.

Relationships between measures of dysfunctional breathing in a population with concerns about their breathing

BACKGROUND

Dysfunctional breathing (DB) is implicated in physical and psychological health, however evaluation is hampered by lack of rigorous definition and clearly defined measures. Screening tools for DB include biochemical measures such as end-tidal CO(2), biomechanical measures such assessments of breathing pattern, breathing symptom questionnaires and tests of breathing function such as breath holding time.

AIM

This study investigates whether screening tools for dysfunctional breathing measure distinct or associated aspects of breathing functionality.

METHOD

84 self-referred or practitioner-referred individuals with concerns about their breathing were assessed using screening tools proposed to identify DB. Correlations between these measures were determined.

RESULTS

Significant correlations where found within categories of measures however correlations between variables in different categories were generally not significant. No measures were found to correlate with carbon dioxide levels.

CONCLUSION

DB cannot be simply defined. For practical purposes DB is probably best characterised as a multi-dimensional construct with at least 3 dimensions, biochemical, biomechanical and breathing related symptoms. Comprehensive evaluation of breathing dysfunction should include measures of breathing symptoms, breathing pattern, resting CO(2) and also include functional measures such a breath holding time and response of breathing to physical and psychological challenges including stress testing with CO(2) monitoring.

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.

Physical activity, lung function, and shortness of breath in the daily life of individuals with asthma

BACKGROUND

The effects of physical activity on asthma have been explored extensively. Exercise can trigger later bronchoconstriction in many patients, and deconditioning due to a sedentary lifestyle may be the consequence. However, the immediate effect of physical activity in asthma and health is bronchodilation. To date, little is known about the association between physical activity and lung function in the daily life of asthma patients.

METHODS

We studied 20 individuals with asthma and 20 control subjects using an electronic diary of activities and spirometry (peak expiratory flow [PEF], FEV(1)). Participants rated their shortness of breath and their intensity of physical and social activity for the preceding 30 min. Assessments were made over the course of 3 weeks, tid (morning, afternoon, evening/night).

RESULTS

Stronger physical activity was concurrently associated with significantly higher lung function. In contrast, it also showed a positive concurrent association with shortness of breath. In prospective cross-lag analyses, lower PEF and FEV(1) earlier in the day predicted lower physical and social activity levels later in the day, but shortness of breath did not.

CONCLUSION

The findings show that detrimental effects observed in exercise-induced bronchoconstriction cannot be generalized to physical activity in daily lives of individuals with asthma. Nevertheless, people with asthma still feel more shortness of breath when being more physically active. They adjust their activity levels throughout the day according to their earlier lung function, but this does not fully explain the concurrent positive association of physical activity and lung function.

Respiratory manifestations of panic disorder: causes, consequences and therapeutic implications

Multiple respiratory abnormalities can be found in anxiety disorders, especially in panic disorder (PD). Individuals with PD experience unexpected panic attacks, characterized by anxiety and fear, resulting in a number of autonomic and respiratory symptoms. Respiratory stimulation is a common event during panic attacks. The respiratory abnormality most often reported in PD patients is increased CO2 sensitivity, which has given rise to the hypothesis of fundamental abnormalities in the physiological mechanisms that control breathing in PD. There is evidence that PD patients with dominant respiratory symptoms are more sensitive to respiratory tests than are those who do not manifest such symptoms, and that the former group constitutes a distinct subtype. Patients with PD tend to hyperventilate and to panic in response to respiratory stimulants such as CO2, triggering the activation of a hypersensitive fear network. Although respiratory physiology seems to remain normal in these subjects, recent evidence supports the idea that they present subclinical abnormalities in respiration and in other functions related to body homeostasis. The fear network, composed of the hippocampus, the medial prefrontal cortex, the amygdala and its brain stem projections, might be oversensitive in PD patients. This theory might explain why medication and cognitive-behavioral therapy are both clearly effective. Our aim was to review the relationship between respiration and PD, addressing the respiratory subtype of PD and the hyperventilation syndrome, with a focus on respiratory challenge tests, as well as on the current mechanistic concepts and the pharmacological implications of this relationship.

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.

Mediators in the dissonance eating disorder prevention program

Previous research has supported thin-ideal internalization as a partial mediator of the effects of the dissonance eating disorder prevention program. The current study replicated previous findings and examined an additional mediator, body dissatisfaction, hypothesized to account for partial intervention effects. As a secondary goal, we developed a more rigorous and accurate test of mediation that accounted for the temporal, causal interplay between mediator and outcome, and controlled for "reverse mediation". Results from a sample of 71 high-risk females (M age = 19.8, SD = 1.3) who participated in a four-week dissonance intervention supported thin-ideal internalization as a partial mediator of the effects of the dissonance intervention on bulimic symptoms, even after controlling for body dissatisfaction as a second mediator. Furthermore, results supported body dissatisfaction as a partial mediator for bulimic symptoms after controlling for thin-ideal internalization. Significant "reverse mediation" effects suggested the reciprocal influence of some risk factors for bulimia nervosa and bulimic symptoms. These results contribute to our understanding of the mediators in the dissonance intervention, which can help refine eating disorder prevention programs.