The goal of this clinical trial is to test if Written Exposure Therapy (WET) works well in a group setting in patients with post-traumatic stress disorder (PTSD).

The main questions it aims to answer are:

• Does group WET lead to a reduction in symptoms of PTSD?
• Is group WET better at reducing the number of patients that drop out of treatment in comparison to group Cognitive Processing Therapy (CPT)?

Participants will:

• Attend 6 weekly sessions of group WET that will be delivered online by two therapists (psychologist and social worker)
• Complete questionnaires relating to their symptoms at different points throughout the treatment

Researchers will evaluate change in PTSD symptoms over time for people who participate in group WET. They will also compare the results of group WET to the results of group CPT to see if group WET shows a similar reduction in symptoms of PTSD and fewer treatment drop-outs.

The primary objective of this study is to evaluate the effectiveness of group WET (G-WET) in reducing symptoms of PTSD in an outpatient hospital setting. In order to do so, we will evaluate outcomes of G-WET from pre- to post-treatment and at one month follow-up. We will also compare outcomes of G-WET to published benchmarks of individual WET outcomes and to a representative cohort of individuals who participate in group CPT at our clinic. A secondary aim of the study is to evaluate attendance and drop-out rates for group WET. In order to achieve this, we will recruit a sample of 63 individuals between the ages of 18 and 65 to participate in a group WET 6-session protocol (1 orientation session and 5 WET sessions) from an outpatient anxiety and related disorders clinic waitlist for group CPT. Participants will complete measures assessing PTSD, related symptoms (e.g., depression, anxiety) and group cohesion at pre-treatment, post-treatment, and 1-month follow-up. Attendance and drop-out rates will also be recorded. We hypothesize that group WET will be associated with significant reductions in PTSD symptoms and related symptoms and low dropout rates (i.e., less than 10%). We also hypothesize that outcomes for group WET will be comparable to those for group CPT and published individual WET benchmarks.

Inclusion Criteria:

• Between the ages of 18 and older
• Diagnosis of PTSD
• Able to provide written informed consent and can read and write in English

Exclusion Criteria:

• Diagnosis of an active severe substance use disorder (SUD)
• Diagnosis of a psychotic disorder (schizophrenia, schizoaffective disorder, etc.)
• Untreated active psychotic, manic or hypomanic symptoms
• Has attempted suicide in the 2 months prior to beginning treatment
• Has engaged in high-risk self-harm (e.g., cutting, burning, asphyxiation) in the 2 months prior to beginning treatment
• Has completed CPT in the past
• Has completed another active PTSD treatment, such as Prolonged Exposure or EMDR within the last year