NCT04770584 · The University of Texas Health Science Center, Houston
Fear and Avoidance in PTSD Patients
What this study is about
The purpose of this research study is to study how the brain learns to avoid certain stimuli or situations using an experimental paradigm. The big goal is to measure brain responses and subject's feelings and expectations when they are learning to actively avoid experimental stimuli, and how fear extinction learning and monetary cost can change how and when subjects are to avoid.
View original scientific description
The purpose of this research study is to study how the brain learns to avoid certain stimuli or situations using an experimental paradigm. The big goal is to measure brain responses and subject's feelings and expectations when they are learning to actively avoid experimental stimuli, and how fear extinction learning and monetary cost can change how and when subjects are to avoid.
Interventions
BEHAVIORAL
Fear Conditioning
Participants will be administered increasing intensities of mild electric shock via electrodes connected to the foot. New Biopac stimulators that can deliver higher shock intensity, provided participants agreement will be used to assure adequate conditioning levels. Stimulation is measures in milliamps (mA), and each delivered stimulation will be 0.5 seconds long (500 milliseconds). To colored (blue, red, \& yellow) light stimuli (CS). The light stimulus is followed by a shock or no shock depending on color.
OTHER
Avoidance conditioning
Via button pressing. Only one stimulus-CS will enable control over experiencing the shock: the participant can press the button during the first 2 seconds of the light presentation to avoid the shock.
OTHER
Pavlovian fear extinction learning
After avoidance conditioning, the CS+ associated with avoidance responding appears with no button to press and no shock is administered.
OTHER
Willingness to pay to avoid shock
On the next day, participants receive a monetary stipend to use to pay to guarantee that they are not to receive any shocks if they press a button from the CS+. This and all previously described experimental phases noted above will occur inside of the fMRI scanner.
Primary outcome measures
Skin Conductance Response (SCR)
Time frame: Experimental Day 1, Experimental Day 2
Skin Conductance Response (SCR) assesses the stress/seat level, or level of anxiety in a particular moment, or in response to a specific cue. SCR will be reported in microsiemens.
Functional MRI (fMRI) responses
Time frame: Experimental Day 1, Experimental Day 2
fMRI data, including blood-oxygen-level-dependent (BOLD) responses, is used in neuroimaging studies assess neural correlate activations and observe the increase/decrease in activation of a particular brain area in response to a specific cue.
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
- 18 - 70 years of age
- Female or Male
- SCID diagnosis consistent with no current psychiatric disorders, and no current PTSD
- History of trauma exposure
- SCID diagnosis consistent with no current psychiatric disorders ("Axis I" disorders).
- No history of trauma exposure
- Willing and able to provide informed consent.
Exclusion criteria
- for ALL subjects:
- History of neurologic disease (e.g. tic disorder)
- Current significant suicidal ideation, plan or intent or suicidal behavior in past 6 months based on CSSRS or Self-injurious behavior that involves suicidal intent, requires medical attention, or occurs daily
- History of seizure or significant head trauma
- History of the serious/significant psychiatric diagnosis ("Axis I" disorders)
- Use of neuroleptics within one year prior to study
- Current substance use (assessed by urine toxicology; positive urine toxicology screen for any substance, with the exception of THC). Per PI judgement and approval: if urine toxicology is positive for a substance, participant may be eligible to proceed with study provided their urine toxicology (or saliva test for THC) is negative at experimental visit(s)
- Pregnancy (to be ruled out by urine ß-HCG)
- Metallic implants or devices contraindicating magnetic resonance imaging
- High risk of adverse emotional or behavioral reaction, and/or an inability to understand study procedures or the informed consent process Additional exclusion criteria for Trauma-exposed healthy controls (TEHC) group and Healthy controls (HC) group:
- Current psychiatric diagnosis ("Axis I" diagnoses)
Where
- Houston, Texas
Collaborators
National Institute of Mental Health (NIMH)
Related conditions & keywords
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 May 5, 2026 · Source of record for eligibility and locations