NCT05467683 · Jasper A. Smits
CO2 Reactivity as a Biomarker of Non-Response to Exposure-Based Therapy
What this study is about
Anxiety-, obsessive-compulsive and trauma- and stressor-related disorders reflect a significant public health problem.
View original scientific description
Anxiety-, obsessive-compulsive and trauma- and stressor-related disorders reflect a significant public health problem.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- 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 criteria
- 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)
Where
- Boston, Massachusetts
- Austin, Texas
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jun 10, 2026 · Source of record for eligibility and locations