PTSD is prevalent among young people, and is distressing and impairing. Face-to-face trauma-focussed CBT (TFCBT) is an effective short-term therapy for PTSD in young people. The researchers previously developed Cognitive Therapy for PTSD (CT-PTSD) in children and young people, and have shown in 2 published RCTs that it is efficacious when delivered face-to-face. However, most young people with PTSD do not receive effective, evidence-based treatments. This is in part due to under-capacity in NHS CAMHS, and in part due to the burden and inconvenience to young people in attending face-to-face appointments in a clinic. In this project the researchers propose to make CT for PTSD widely available to young people by delivering the therapy via the internet, with therapist support. The rationale for this approach is that (1) young people will engage with internet-delivered therapy, and online therapies for other disorders such as depression have demonstrated efficacy in clinical trials; (2) effective online therapies for adults with PTSD have been developed and evaluated; (3) no online treatments for young people with PTSD have yet been developed.

An uncontrolled case series will be run with N=6 young patients. Young people who are referred to the South London and Maudsley NHS Foundation Trust CAMHS service, and who meet the eligibility criteria, will be invited to take part in the case series. After both the young person and their carer or parent have provided informed consent (or assent), they will complete several baseline assessment measures. These measures will be completed at a face-to-face meeting in the Tier 4 National and Specialist Trauma, Anxiety and Depression (TAD) NHS clinic, and online. The young person and family will meet the young person's therapist face-to-face at this initial assessment meeting. After assessment, the young person that will be treated remotely using iCT for up to 12 weeks.

This treatment will include regular (at least weekly) telephone contact with the therapist, and other contact with the therapist during the week using a messaging function within the iCT App. The young person will be asked to complete a mood rating and a brief 8-item questionnaire about PTSD symptoms once a week during treatment: this mirrors what happens during standard face-to-face care in the TAD NHS clinic. At mid treatment, the young person will be asked to complete one additional 25-item questionnaire about thoughts related to trauma. Risk monitoring including monitoring of adverse events will be carried out during weekly phone calls.

Post treatment, the young person will attend the TAD NHS clinic for a face-to-face clinical interview and will complete a questionnaire pack online. At this meeting, the young person will complete feedback ratings on the acceptability of the design of online treatment modules using 4 simple 0-10 scales (about the overall design appeal, ease-of-use, comprehension, and likelihood of recommending the program to a friend with similar problems). The young person will be interviewed about their experience of using the iCT program (an "exit interview"). Acceptability of the questionnaire battery will be assessed by asking young people to complete an end-of-treatment rating using a 0-100 scale. The young people's parents or carers will also take part in a clinical interview about the young person, will complete a questionnaire pack online, and will be invited to take part in an interview about their experience as a parent or carer of using the iCT program.

N=6 young people will be treated as part of this case series. Young people's and their parents' qualitative feedback on the acceptability of the iCT programme will be reported using data from the exit interviews and from the acceptability rating scales. Averse events during therapy will also be reported. Reliable Clinical Change on a standardised questionnaire of PTSD symptoms (the CPSS-5) will be reported as a preliminary signal of clinical effect. Reliable Clinical Improvement is shown by a reduction of 8 points on the CPSS-5. Acceptability of the outcome measures will be gauged by scrutinising completion rates.