Dowling, Nicki AMerkouris, Stephanie SYoussef, George JLubman, Dan IBagot, Kathleen LHawker, Chloe OPortogallo, Hannah JThomas, Anna CRodda, Simone2026-05-202026-05-202022-08-23JMIR Research Protocols, ISSN: 1929-0748 (Print); 1929-0748 (Online), JMIR Publications, 11(8), e38958-. doi: 10.2196/389581929-07481929-0748http://hdl.handle.net/10292/21157BACKGROUND: The presence of discrete but fluctuating precipitants, in combination with the dynamic nature of gambling episodes, calls for the development of tailored interventions delivered in real time, such as just-in-time adaptive interventions (JITAIs). JITAIs leverage mobile and wireless technologies to address dynamically changing individual needs by providing the type and amount of support required at the right time and only when needed. They have the added benefit of reaching underserved populations by providing accessible, convenient, and low-burden support. Despite these benefits, few JITAIs targeting gambling behavior are available. OBJECTIVE: This study aims to redress this gap in service provision by developing and evaluating a theoretically informed and evidence-based JITAI for people who want to reduce their gambling. Delivered via a smartphone app, GamblingLess: In-The-Moment provides tailored cognitive-behavioral and third-wave interventions targeting cognitive processes explicated by the relapse prevention model (cravings, self-efficacy, and positive outcome expectancies). It aims to reduce gambling symptom severity (distal outcome) through short-term reductions in the likelihood of gambling episodes (primary proximal outcome) by improving craving intensity, self-efficacy, or expectancies (secondary proximal outcomes). The primary aim is to explore the degree to which the delivery of a tailored intervention at a time of cognitive vulnerability reduces the probability of a subsequent gambling episode. METHODS: GamblingLess: In-The-Moment interventions are delivered to gamblers who are in a state of receptivity (available for treatment) and report a state of cognitive vulnerability via ecological momentary assessments 3 times a day. The JITAI will tailor the type, timing, and amount of support for individual needs. Using a microrandomized trial, a form of sequential factorial design, each eligible participant will be randomized to a tailored intervention condition or no intervention control condition at each ecological momentary assessment across a 28-day period. The microrandomized trial will be supplemented by a 6-month within-group follow-up evaluation to explore long-term effects on primary (gambling symptom severity) and secondary (gambling behavior, craving severity, self-efficacy, and expectancies) outcomes and an acceptability evaluation via postintervention surveys, app use and engagement indices, and semistructured interviews. In all, 200 participants will be recruited from Australia and New Zealand. RESULTS: The project was funded in June 2019, with approval from the Deakin University Human Research Ethics Committee (2020-304). Stakeholder user testing revealed high acceptability scores. The trial began on March 29, 2022, and 84 participants have been recruited (as of June 24, 2022). Results are expected to be published mid-2024. CONCLUSIONS: GamblingLess: In-The-Moment forms part of a suite of theoretically informed and evidence-based web-based and mobile gambling interventions. This trial will provide important empirical data that can be used to facilitate the JITAI's optimization to make it a more effective, efficient, and scalable tailored intervention. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry (ANZCTR) ACTRN12622000490774; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=380757&isClinicalTrial=False. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): PRR1-10.2196/38958.© Nicki A Dowling, Stephanie S Merkouris, George J Youssef, Dan I Lubman, Kathleen L Bagot, Chloe O Hawker, Hannah J Portogallo, Anna C Thomas, Simone N Rodda. Originally published in JMIR Research Protocols (https://www.researchprotocols.org), 23.08.2022. This is an open-access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in JMIR Research Protocols, is properly cited. The complete bibliographic information, a link to the original publication on https://www.researchprotocols.org, as well as this copyright and license information must be included.addictionecological momentary interventiongamblinginterventionjust-in-time adaptive interventionmHealthmicrorandomized trialmobile healthmobile phoneprotocolrelapsetreatment4203 Health Services and Systems42 Health SciencesClinical Trials and Supportive ActivitiesHealth DisparitiesClinical ResearchHealth Disparities and Racial or Ethnic Minority Health ResearchSocial Determinants of HealthBehavioral and Social Science3.1 Primary prevention interventions to modify behaviours or promote wellbeing3 Good Health and Well Being1103 Clinical Sciences1117 Public Health and Health Services4203 Health services and systems4206 Public healthJournal ArticleOpenAccess10.2196/38958