A Pilot Participatory Program Evaluation of a Virtual Trauma Support Program for Autistic Adults

The goal of this single-group clinical trial is to learn about the initial efficacy and feasibility of telehealth-delivered Written Exposure Therapy (WET) for autistic adults with traumatic stress symptoms. The main questions the investigators aim to answer are: * Do symptoms of posttraumatic stress disorder (PTSD) and co-occurring mental health concerns decrease after receiving WET? * Do biobehavioral health outcomes, including objective (Fitbit indicators of activity, sleep, and heart rate) and subjectively-reported health variables (e.g., sleep, pain, health-related quality of life), improve after receiving WET? * How do autistic adults experience WET, and how can this program be modified and enhance in the future in collaboration with autistic adults? Participants will complete the following as part of the study, which is completed entirely over telehealth. * Participants will first complete an initial assessment, involving brief measures of cognition and autistic traits, as well as interviews and questionnaires about PTSD, mental health, and physical health. If eligible, participants will proceed to the following steps: * Eligible participants will then start wearing a Fitbit, to be used for the duration of the study. * Participants will then participate in 5 weekly virtual visits involving the WET protocol, including weekly brief assessment of PTSD and mental and physical health. * Then, participants will complete a sixth virtual visit the following week where PTSD, mental and physical health, and treatment feedback are assessed. * Lastly, participants will complete virtual visits 1 and 6 months later involving re-assessment of PTSD and mental and physical health. Therefore, this is a pre-post single group design, where all participants will receive WET to establish initial efficacy and feasibility. Investigators will also consult with an autistic advisory board throughout the project, and make adaptations as recommended in consultation with autistic adults. The goal is to better understand the initial efficacy and feasibility of WET for supporting autistic adults who have experienced trauma.

Inclusion Criteria: * Autistic * Age 18 years or over * Has experienced trauma and reports clinically significant symptoms of traumatic stress (clinically elevated score on either Posttraumatic Symptom Checklist (PCL-5) or Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (SCID-5), and/or other self-report/interview evidence of significant traumatic stress symptoms for which participant wants support/program * Comfortable speaking and writing in English * Full Scale Intelligence Quotient (FSIQ) score \>= 65 (given written nature of Written Exposure Therapy) on the Wechsler Abbreviated Scale of Intelligence-Second Edition (WASI-2) * Access to device with internet access for telehealth visits Exclusion Criteria: * Participant is not Autistic * Participant is unable to understand English * Participant is currently receiving trauma-focused therapeutic services * Participant does not have access to internet connected device for telehealth visits * Participant receives Full Scale Intelligence Quotient (FSIQ) score \< 65 on the Wechsler Abbreviated Scale of Intelligence-Second Edition (WASI-2) * If there are significant safety concerns for any participant (e.g., imminent risk of harm to self or other) the Principal Investigator may determine whether it is not in the adult's best interest to be enrolled given that this study does not provide care/services relating to active risk.