Respiratory Training vs Interoceptive Exposure in the Treatment of Transdiagnostic Pathological Anxiety


Purpose of the Research: The primary aim of the proposed study is to conduct a randomized parallel-group 3-arm clinical trial comparing two mechanistically distinct interventions for pathological anxiety – (1) Interoceptive Exposure (IE) utilizing graduated exposure to somatic cues (respiratory, cardiac, vestibular) with the primary aim of reducing fear responding to the presence of interoceptive perturbations; (2) Capnometry-Guided Respiratory Intervention (CGRI) aimed at raising end-tidal CO2 levels thereby lowering hyperventilation-induced respiratory alkalosis and its associated fear-eliciting somatic reactions; and (3) Psycho-education about anxiety and its effects (PsyEd), which will serve as a credible control comparator.

Full Title of Study: “Respiratory Training vs Interoceptive Exposure in the Treatment of Transdiagnostic Pathological Anxiety: A Randomized Clinical Trial”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: Single (Outcomes Assessor)
  • Study Primary Completion Date: May 2025

Detailed Description

Anxiety sensitivity – the tendency to perceive anxiety as threatening – is a widely recognized risk factor for the development of panic disorder and other anxiety-related psychopathology. Interoceptive exposure therapy consisting of repeated exposure to interoceptive cues using respiratory provocation challenges such as hyperventilation and inhalation of various concentrations of CO2-enriched air have shown promise in reducing AS and are often included in cognitive-behavioral treatments of panic disorder with or without agoraphobia.However, some patients are unwilling to undergo exposure-based treatments, while others who do show only partial response or subsequent relapse. Alternatively, low end-tidal CO2 (ETCO2), which is an accompanying feature of hyperventilation, has been associated with a variety of anxiety disorders, including panic disorder and social phobia. More recently, researchers have examined the efficacy of capnometry-guided respiratory intervention (CGRI) as a method for increasing ETCO2 and thereby reducing hyperventilation-induced anxiety/panic symptoms. Promising preliminary efficacy studies have shown that CGRI results in decreased panic symptom frequency and severity at a rate comparable to that of cognitive therapy. A recent uncontrolled proof-of-concept study showed that CGRI led to significant reductions in trauma symptoms in a sample of patients meeting DSM-5 criteria for PTSD. However, neither IE or CGRI has been adequately evaluated in the treatment of anxiety disorders other than panic disorder with or without agoraphobia.


  • Behavioral: Interoceptive Exposure
    • See: Arm/group descriptions
  • Device: Capnometry-Guided Respiratory Intervention
    • See: Arm/group descriptions
  • Behavioral: Psycho-Education
    • See: Arm/group descriptions

Arms, Groups and Cohorts

  • Experimental: Interoceptive Exposure (IE)
    • Participants assigned to the interoceptive exposure condition will receive twice-weekly 90-minute in-person treatment sessions for four weeks. This treatment will include education about anxiety and factors that maintain anxiety symptoms. In addition, participants will be asked to perform exercises designed to activate potentially distressing – but harmless – bodily sensations that are commonly associated with stress and anxiety. Participants will also be encouraged to practice these exercises daily at home.
  • Experimental: Capnometry-Guided Respiratory Intervention (CGRI)
    • If assigned to this condition, participants will be expected to complete twice-daily 17-minute tablet-assisted breathing exercises at home for four weeks. They will also receive brief phone check-ins with their study therapist weekly to review progress and troubleshoot any problems they may be experiencing. Last, these participants will have access to a paced-breathing app that provides audio recordings to maintain specified breathing rates for up to 10 minutes.
  • Active Comparator: Psycho-Education (PsyEd)
    • If assigned to this condition, participants will undergo one 90-minute video conferencing session with a therapist. During this session, they will be provided information about the nature and causes of anxiety-related disorders and learn tips for coping with anxiety symptoms when they arise. At the end of this session, participants will receive handouts that will help reinforce what they’ve learned.

Clinical Trial Outcome Measures

Primary Measures

  • Overall Anxiety Severity and Impairment Scale
    • Time Frame: Pre-Treatment (Week 0), Post-treatment (Week 5), 2-Month Follow-Up (Week 13)
    • Change from baseline in self-reported transdiagnostic anxiety symptoms (range = 0 – 20, with higher scores indexing more symptoms).
  • Computerized Hamilton Anxiety Scale
    • Time Frame: Pre-Treatment (Week 0), Post-treatment (Week 5), 2-Month Follow-Up (Week 13)
    • Change from baseline in anxiety symptom severity. Each item is assessed both in terms of frequency and severity. Scores on these probes are summed and divided by the number of response options. Higher scores index higher severity.

Secondary Measures

  • Sheehan Disability Scale
    • Time Frame: Pre-Treatment (Week 0), Weekly Assessments (Weeks 1 – 4), Post-treatment (Week 5), 2-Month Follow-Up (Week 13)
    • Change from baseline in overall disability (range = 0 – 30, with higher scores indexing more disability).
  • PROMIS – Global Health (Mental Health Subdomain)
    • Time Frame: Pre-Treatment (Week 0), Weekly Assessments (Weeks 1 – 4), Post-treatment (Week 5), 2-Month Follow-Up (Week 13)
    • Change from baseline in quality of life (range = 4 – 20, with higher scores indexing higher quality of life).
  • Anxiety Sensitivity Composite Measure
    • Time Frame: Pre-Treatment (Week 0), Weekly Assessments (Weeks 1 – 4), Post-treatment (Week 5), 2-Month Follow-Up (Week 13)
    • This composite measure will incorporate scores on the Anxiety Sensitivity Index-3 (ASI-3), Body Sensations Questionnaire (BSQ), and Texas Multi-Factor Anxiety Sensitivity Scale (TMASS). Scores on each of these individual measures will be transformed into z scores and then averaged to derive this composite index. We will measure change from baseline in anxiety sensitivity.
  • Modified DIAMOND
    • Time Frame: Pre-Treatment (Week 0), 2-Month Follow-Up (Week 13)
    • Change from baseline in DIAMOND Diagnostic Interview + Health Anxiety Questionnaire scores.

Participating in This Clinical Trial

Inclusion Criteria

1. Clinically elevated anxiety as indicated by an eight or higher on the Overall Anxiety Severity and Impairment Scale (OASIS). 2. Meets DSM-5 criteria for one or more of the following anxiety or trauma-related disorders as their "primary" mental disorder:

  • Generalized Anxiety Disorder – Panic Disorder – Health Anxiety – Agoraphobia – Social Anxiety Disorder – Posttraumatic Stress Disorder – Acute Stress Disorder – Adjustment Disorder with primary anxious mood 3. No current use of psychotropic medications or stable on current medications for at least 3 months 4. Age 18+. 5. Able to arrange transportation to our laboratory for study appointments. Exclusion Criteria:

1. No history of medical conditions that would contraindicate participation in fear-provocation or respiratory challenges, including:

  • Cardiovascular or respiratory disorders – High blood pressure – Epilepsy – Strokes – Seizures – History of fainting – Pregnant or lactating 2. Not currently receiving other psychological treatment for anxiety. 3. No history of a suicide attempt within the past 6 months. 4. No history of psychosis within the past 6 months. 5. No history of alcohol or substance use disorder (with the exception of nicotine) within the past 3 months. 6. Does not endorse COVID-19 symptoms during the screening phase.

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: N/A

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • University of Texas at Austin
  • Collaborator
    • Freespira, Inc.
  • Provider of Information About this Clinical Study
    • Principal Investigator: Michael J. Telch, Professor of Psychology – University of Texas at Austin
  • Overall Contact(s)
    • Michael J Telch, PhD, 512-814-5480,


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