Age

18–any

Sex

ALL

Healthy volunteers

Not accepted

be enrolled in residential SUD treatment at MTC
meet criteria for PTSD based on the Clinician-Administered PTSD Scale for DSM-5
be 18 years of age or older
have sufficient memory of the index trauma to write about it
be sufficiently able to speak, read, and write in the English language to complete WEST therapy and study assessments.

Inability to give informed consent for any reason (e.g., cognitive impairment)
Presence of acute psychosis that would interfere with study participation
Suicide attempt within the past 3 months
History of psychiatric hospitalization within the past month
Presence of any other psychiatric instability or suicidality that would interfere with study participation
Planning to leave residential treatment before WEST could realistically be completed as determined by the investigator
Lack of access to a mobile phone after treatment discharge

Written Exposure in Substance Treatment (WEST 3.0): Randomized Controlled Trial