Towards Participatory Precision Health: Systematic Review and Co-designed Guidelines For Adolescent Just-in-time Adaptive Interventions

BackgroundAdolescence and young adulthood (10-25 years) constitute a sensitive developmental period marked by rapid biological, psychological, and social changes, during which preventative health interventions can shape long-term outcomes. Mobile health (mHealth) tools offer opportunities for tailored support but often with limited adaptation to adolescents dynamic contexts, resulting in inconsistent engagement and effects. Just-in-time adaptive interventions (JITAIs), which tailor support in real time using ongoing data, are increasingly explored as precision health strategies. However, how these mechanisms are designed, implemented, and evaluated for adolescents has not been systematically reviewed. ObjectivesThis review aimed to identify and synthesize existing JITAIs developed for adolescents. It examined how adaptive mechanisms, including tailoring variables, intervention options, decision rules and decision points, are designed to respond to adolescents contexts and specific health goals. The review also evaluated methodological quality in order to guide the development of future precision health interventions. MethodsThe review methods followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Twelve databases (PubMed, Scopus, Web of Science, PsycINFO, Embase, CINAHL, IEEE Xplore, ACM Digital Library, Cochrane Central, Dimensions, WHO Global Index Medicus, Google Scholar) were searched for studies published between 2013 and February 2025. Eligible studies were peer-reviewed, involved adolescents aged 10-25 years, and reported real-time adaptive mHealth interventions consistent with JITAI design principles. Screening, data extraction, and quality appraisal (using the appropriate Joanna Briggs Institute checklists for each study design) were conducted independently by two separate reviewers, with adolescent co-authors contributing to all phases. Given heterogeneity and high risk of bias across studies, results were synthesized narratively and organized around JITAI components and their corresponding health outcomes. ResultsFrom 3,227 unique records, 64 studies (58 unique interventions) were included. Interventions targeted substance use (N=26 studies), mental health (N=19), and physical health including chronic conditions (N=13). Most applied behavioral or cognitive frameworks to guide intervention design. Tailoring mechanisms relied heavily on self-reported data, with emerging use of passive sensing and machine learning for more dynamic adaptation. Decision rules were typically threshold- or schedule-based. Methodological limitations, incomplete reporting, and inconsistent outcomes were widespread. Ethical and engagement considerations were rarely addressed beyond isolated co-design examples. ConclusionsAdolescent-focused JITAIs hold promise for addressing substance use, mental health, and physical health needs in this population, but the current evidence base is constrained by methodological weaknesses, reliance on self-report, and limited ethical transparency. We provide recommendations informed gaps in the review evidence and interpretation by adolescent co-authors. In particular, future research should prioritize microrandomized trials to disentangle adaptive components and embed participatory co-design to ensure contextual relevance. PROSPERO registrationCRD42023473117