Abstract: This pilot study evaluated ACT Vet, a smartphone-delivered Acceptance and Commitment Therapy (ACT) application (app) designed for UK Armed Forces veterans experiencing post-traumatic stress disorder (PTSD) and gambling harm. The app, co-designed with veterans and experts, delivers a structured, self-guided programme to build upon psychological flexibility through the core ACT components. The app included ACT modules, breathing exercises, reflection prompts, and support signposting. Outcome measures were collected across five time points. A total of 250 people completed screening, with 79 eligible veterans and 35 starting the intervention. Of these, 24 completed sufficient data for analysis.
Key Findings:
• Psychological flexibility significantly increased.
• PTSD symptoms significantly reduced.
• Scores on gambling urges halved.
• Mediation analysis showed that increased psychological flexibility reduced gambling urges by firstly reducing negative PTSD symptoms.
• Secondary outcomes showed improvements in alcohol use, quality of life, suicidality, and loneliness.
• App usability was rated highly.
Qualitative interviews highlighted the app’s simplicity, helpful structure, and calming features. Veterans valued its ease of access and support during distressing moments. Suggestions for improvement included clearer task tracking and more diverse imagery. ACT Vet is a promising digital tool for veterans with PTSD and gambling harm, with early evidence of feasibility, engagement, and clinical benefit. A full Randomised Controlled Trial is now recommended, alongside continued development and exploration of NHS and thirdsector integration.