Mechanisms of Written Exposure Therapy in Residential SUD Treatment

The goal of this clinical trial is to learn how Written Exposure Therapy (WET), a brief treatment for PTSD, works among individuals with substance use disorders (SUD) engaged in residential SUD treatment and how biology may influence treatment. The main questions it aims to answer are:

• Does WET improve PTSD and substance use outcomes among individuals with SUD+PTSD?
• Does WET improve physiological responses and craving to trauma cues?
• Do sex hormones influence changes physiological responses and craving during treatment among women?

Participants will:

• Complete WET or a neutral writing in addition to their residential SUD treatment
• Complete two laboratory sessions before and after treatment
• Complete follow-up surveys and interviews at 1- and 3-months post-treatment

Study Overview

• Status: Not yet recruiting
• Conditions: Substance Use Disorder (SUD); PTSD - Post Traumatic Stress Disorder
• Intervention / Treatment: Behavioral: Written Exposure Therapy; Behavioral: Neutral Writing

• Study Type: Interventional
• Enrollment (Estimated): 108
• Phase: Not Applicable

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. ability to understand and sign informed consent
2. ability to write in English;
3. age between 18-55 (average age of menopause in the US)
4. [women only] naturally cycling (i.e., regular cycles, not on gonadal-related hormones)
5. current diagnosis of a moderate or severe DSM-5 SUD
6. current diagnosis of DSM-5 PTSD
7. sufficient memory of the trauma to write about the event
8. at least 5 business days left in their residential treatment episode (to allow for 5 treatment sessions).

Exclusion Criteria:

1. presence of a psychiatric or medical condition that would interfere with participation (e.g., severe, uncontrolled psychosis)
2. prescription of a PRN benzodiazepine
3. current PTSD treatment

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: WET; This arm will receive Written Exposure Therapy in addition to residential SUD treatment.	Behavioral: Written Exposure Therapy; Written Exposure Therapy (WET) is a five-session manualized treatment for PTSD. At the first session, psychoeducation about common reactions to trauma and PTSD are presented followed by a 30-minute written exposure. Following the exposure, a 10-minute check-in is completed, and individuals are instructed not to avoid any thoughts/feelings/ images related to the trauma between sessions. All subsequent sessions follow this structure: check-in on avoidance and feedback on writing, written exposure, and brief check-in post-writing about the writing process.
Other: Neutral Writing; This arm will receive five sessions of neutral writing in addition to residential SUD treatment.	Behavioral: Neutral Writing; Participants will complete five writing prompts that are not intended to provoke emotional responses. Examples of these prompts include writing about the food they ate the day prior or what they did yesterday. Participants will be instructed to not discuss their thoughts and feelings regarding these topics. Neutral writing will provide control for time and clinician contact.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
PTSD Symptom Severity	The PTSD Checklist for DSM-5 (PCL-5) is a 20-item self-report measure of symptoms of PTSD as defined by the DSM-5. Participants are instructed to keep in mind the identified worst event when responding to the items. Items are summed to create a total score which ranges from 0-80; a total score cut-off of 33 is recommended for identifying probable PTSD.	Baseline, Immediately after intervention, 1- and 3-Month Post-Discharge
Days of Substance Use	The Timeline Follow-Back (TLFB) method will be used to assess past 30-day substance use frequency and quantity. The TLFB will be administered by phone at 1-month and 3-month post-discharge. Days of use at Baseline will ask about the 30 days prior to entering treatment.	Baseline, 1- and 3-Month Post-Discharge
Heart Rate (HR)	Biopac MP150 for Windows will be used to collect electrocardiogram (ECG) data at a sampling rate of 1000 Hz. ECG is measured using three disposable Ag/AgCl electrodes and data are processed using MindWare software. HR will be derived by spectral analysis of 1-min epochs with a Hamming windowing function and log transformed. HR will be measured continuously during the trauma-cue reactivity paradigm (primary outcome), and during WET treatment sessions (secondary outcome). Average HR in beats per minute will be calculated during the trauma-cue (primary) and for each 30-minute writing session (secondary).	Baseline, Intervention Sessions, Immediately after intervention
Skin Conductance Response (SCR)	Biopac MP150 for Windows will be used to collect electrodermal activity (EDA) data at a sampling rate of 1000 Hz. EDA is measured using two finger electrodes and data are processed using MindWare software. EDA will be measured continuously during the trauma-cue reactivity paradigm (primary outcome), and during WET treatment sessions (secondary outcome). SCR will be calculated as the maximum SC amplitude during the trauma-cue adjusted for the average SC amplitude during the final 30-seconds of the rest phase (primary outcome). SCR during each WET session (secondary outcome) will be calculated as the maximum EDA amplitude during the written exposure, adjusted for baseline amplitude.	Baseline, Intervention Sessions, Immediately after intervention
High-Frequency Heart Rate Variability (HF-HRV)	Biopac MP150 for Windows will be used to collect electrocardiogram (ECG) data at a sampling rate of 1000 Hz. ECG is measured using three disposable Ag/AgCl electrodes and data are processed using MindWare software. HF-HRV will be derived by spectral analysis of 1-min epochs with a Hamming windowing function and log transformed. HF-HRV will be derived from ECG R-R intervals (inter-beat interval). Standard recommendations for the high frequency band settings (0.12- 0.40 Hz) will be used. HF-HRV will be measured during the trauma-cue reactivity paradigm (primary outcome), and during WET treatment sessions (secondary outcome). Average HF-HRV will be calculated during the trauma-cue (primary) and for each 30-minute writing session (secondary).	Baseline, Intervention Sessions, Immediately after intervention
Trauma-Reactive Craving	The Craving Scale is a 3-item validated measure of substance use craving. It uses a scale of 0-9 to assess: (1) the strength of craving in the past 24 hours, (2) the likelihood of use in an environment they have used in before, and (3) strength of cued craving. Craving will be assessed at all time points. Craving before and after the trauma-cue reactivity paradigm will be assessed and trauma-reactive craving will be the change in craving pre/post-trauma-cue (primary outcome). During the WET Intervention Sessions, substance use craving pre- and post- writing will be assessed and trauma-reactive craving will be calculated as post-writing craving adjusted for pre-writing craving (secondary outcome).	Baseline, Intervention Sessions, Immediately after intervention, 1- and 3-Month Post-Discharge Follow-ups

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Consequences of Substance Use	The Short Inventory of Problems - Revised (SIP-R) is a 17-item self-report of adverse consequences associated with drug or alcohol use in four domains: physical, social, intrapersonal, interpersonal, and impulse control. Items are rated on a scale of 0 (Never) to 3 (Daily or Almost Daily) representing the frequency of each consequence. A total score is calculated by summing all items, with higher scores reflecting greater consequences.	Baseline, Immediately after intervention, 1- and 3-Month Post-Discharge

Collaborators and Investigators

• Sponsor: Mclean Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): December 1, 2029
• Study Completion (Estimated): March 1, 2030

Study Registration Dates

• First Submitted: January 28, 2026
• First Submitted That Met QC Criteria: February 4, 2026
• First Posted (Actual): February 9, 2026

Study Record Updates

• Last Update Posted (Actual): February 9, 2026
• Last Update Submitted That Met QC Criteria: February 4, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: fear extinction; Substance Use Disorder; Written Exposure Therapy; PTSD treatment; treatment mechanisms
• Additional Relevant MeSH Terms: Trauma and Stressor Related Disorders; Mental Disorders; Chemically-Induced Disorders; Stress Disorders, Traumatic; Substance-Related Disorders; Combat Disorders
• Other Study ID Numbers: 2025P003371

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No