Indicated Stress Prevention Addressing Adolescents with High Stress Levels Based on Principles of Acceptance and Commitment Therapy: A Randomized Controlled Trial

<b><i>Introduction:</i></b> Stress affects many adolescents and is associated with physical and mental health symptoms that can have a negative impact on normative development. However, there are very few evidence-based, specific treatment approaches. The aim of the study was to investigate an eight-session group intervention using components of Acceptance and Commitment Therapy (ACT) enriched with elements of CBT (psychoeducation, problem solving) and art therapy, compared to a waitlist control (WLC) group, regarding its efficacy in reducing stress and associated symptoms. <b><i>Methods:</i></b> We conducted a randomized controlled trial in eight cohorts. Eligible participants were 13–18 years old with elevated stress levels. Via block-randomization (<i>n</i> = 70), participants were allocated to receive ACT (<i>n</i> = 38) or WLC (<i>n</i> = 32) and subsequent ACT. We used a multimodal assessment (self-reports, interviews, ecological momentary assessment, physiological markers) before treatment (T1), after the training of the ACT group (T2) and after subsequent training in the WLC group (T3). Primary outcome was perceived stress at T2 assessed with the Perceived Stress Scale. The trial was preregistered at the German Clinical Trials Register (ID: DRKS00012778). <b><i>Results:</i></b> Results showed significantly lower levels of perceived stress in the ACT group at T2, illustrating superiority of ACT compared to WLC with a medium to large effect size (<i>d</i> = 0.77). Furthermore, the training was effective in the reduction of symptoms of school burnout and physical symptoms associated with stress. <b><i>Conclusion:</i></b> Indicated prevention, especially when based on the principles of ACT and CBT, seems efficient in significantly decreasing stress in adolescents with increased stress.