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CO2 Reactivity as a Biomarker for Exposure-Based Therapy Non-Response

This study is looking for 600 adults, aged 18-70, who have been diagnosed with panic disorder, social anxiety disorder, generalized anxiety disorder, obsessive-compulsive disorder, or post-traumatic stress disorder. The goal is to see if a simple test called a CO2 challenge can predict whether someone will benefit from Exposure-Based Therapy (EBT). EBT involves 12 weekly, one-hour sessions. Researchers want to find out if this CO2 test can help doctors decide if EBT is the right treatment for you. The study is currently unclear on its recruitment status.

Study design
This interventional study plans to enroll 600 participants. It will assess CO2 reactivity before participants receive Exposure-Based Therapy.
What's involved
You would participate in 12 one-hour Exposure-Based Therapy sessions over 12 weeks. There will also be a CO2 reactivity assessment before treatment.
Compensation
Not stated in the trial record.
Follow-up
The primary endpoint, non-response to exposure-based therapy, is measured at Week 13 (post-treatment).

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT05467683

CO2 Reactivity as a Biomarker of Non-Response to Exposure-Based Therapy

Recruiting
NAAges 18–70InterventionalTreatment
Jasper A. Smits
~600 participants
Updated 2026-06-10 on ClinicalTrials.gov
What's tested:Exposure-Based Therapy

At a glance

Recruiting sites
2 of 2 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Non-response to exposure-based therapy
Measured over Week 13 (post-treatment)

Conditions

Obsessive-Compulsive Disorder
Post Traumatic Stress Disorder
Generalized Anxiety Disorder
Social Anxiety Disorder
Panic Disorder

Explore related trials

Generalized Anxiety DisorderObsessive Compulsive DisorderPanic DisorderPost-Traumatic Stress DisorderSocial Anxiety Disorder

Where it's being run

2 sites across 2 states
Massachusetts1
Texas1

Study leadership

  • Jasper Smits, Ph.D. · PRINCIPAL_INVESTIGATOR · The University of Texas at Austin
  • Michael Otto, Ph.D. · PRINCIPAL_INVESTIGATOR · Boston University

Who to contact

Michael Otto, Ph.D.
[email protected]
617-353-9610
Email the study team

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Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

A primary DSM-5 diagnosis of panic disorder (with or without an agoraphobia diagnosis), social anxiety disorder, generalized anxiety disorder, obsessive-compulsive disorder, or post-traumatic stress disorder as assessed by the Structured Clinical Interview for the DSM-5 (SCID-5)
A score of 8 or greater on the Overall Anxiety Severity and Impairment Scale (OASIS)
Ages 18 to 70
Willingness and ability to provide informed consent and comply with the requirements of the study protocol.
Proficiency in English (because assessment instruments have only been validated in English)

Exclusion

A lifetime history of bipolar or psychotic disorders, substance use disorders (other than nicotine) or eating disorder in the past 6 months; serious cognitive impairment.
Active suicidal ideation with at least some intent to act with or without specific plan (a rating of 4 for suicidal ideation on the Columbia-Suicide Severity Rating Scale) or suicidal behaviors (actual attempt, interrupted attempt, aborted or self-interrupted attempt, or preparatory acts or behavior) within the past 6 months.
Medical conditions contraindicating CO2 inhalation or hyperventilation challenge (e.g., cardiac arrhythmia, cardiac failure, asthma, lung fibrosis, high blood pressure, epilepsy, or stroke).
Pregnancy or lactation
Ongoing psychotherapy directed toward the primary disorder.
Pharmacological treatment started within 8 weeks prior to the screen (patients "stable" on their medication regimen will be included and their medication status will be included as a variable in the model)

What this trial measures

  • Non-response to exposure-based therapyWeek 13 (post-treatment)

    Participants will be classified as non-responders if their Clinical Global Impression - Global Improvement (CGI-I) score is 3 or above OR if their Overall Anxiety Severity and Impairment Scale (OASIS) score has not improved by at least 4 points.