Study protocol: A micro-randomized trial for a just-in-time adaptive intervention to manage problem anger after trauma (Shift)

Acta Psychol (Amst). 2026 Mar 21;265:106703. doi: 10.1016/j.actpsy.2026.106703. Online ahead of print.

ABSTRACT

BACKGROUND: Problem anger after experiencing trauma is a common mental health issue. Shift is a new cognitive-behavioral based app, co-designed with users and experts, that works by prompting users to report their current anger state, and delivering personalized support to manage anger accordingly.

OBJECTIVE: The aim of this study is to investigate whether prompting users to engage with Shift modules tailored to their in-the-moment anger state, as compared to no prompt, reduces near-term anger intensity. We also aim to investigate whether this effect is moderated by the anger state, or days in the study. Finally, we aim to evaluate the acceptability of the intervention.

STUDY DESIGN: A micro-randomized trial will be implemented with 65 adults with problem anger and a history of trauma exposure. For 30 days, four times a day, each participant will be prompted to self-report their current anger state and will be micro-randomized to be shown a Shift module tailored to their in-the-moment anger state. Post intervention surveys, and app use and engagement indices will be analyzed to evaluate the acceptability of the intervention. Self-report assessments of anger intensity will be analyzed to optimize decision rules for a just-in-time adaptive intervention (JITAI) to manage problem anger.

SIGNIFICANCE: This will be the first digital trial using micro-randomization to optimize a JITAI for problem anger in a population who have experienced trauma, and one of the few micro-randomized trials to optimize digital mental health tools to manage emotional dysregulation.

REGISTRATION: Australia and New Zealand Clinical Trials Registry ACTRN12624001400550.

PMID:41865715 | DOI:10.1016/j.actpsy.2026.106703