An app responding to behavior of people to promote mental wellbeing in anxious youth

Anxiety disorders are prevalent among youth, yet access to effective treatments is limited. This study investigates the efficacy of the SMILE app, a smartphone application that delivers cognitive behavioral therapy (CBT)-based interventions to youth aged 12–21 with severe anxiety symptoms. The SMILE app uses mobile sensing technology to provide personalized interventions, addressing individual behavioral patterns. In this two-arm randomized controlled trial, 107 participants, aged 12–21 with severe anxiety symptoms, were assigned to the intervention group, using the SMILE app in combination with a mobile sensing app, or the control group, using only a mobile sensing app. The primary outcome was anxiety symptoms measured by the SCARED scale. Secondary outcomes included depression and insomnia. Assessments were conducted at baseline, post-intervention (4 weeks), and follow-up (12 weeks). Data analysis followed an intention-to-treat approach. Anxiety symptoms significantly decreased in the treatment group compared to the control group at 4 weeks (−0.48, SE = 0.17; p = 0.006, 95% CI: −0.82 to −0.14), and marginally at 12 weeks (b = −0.32, SE = 0.18; p = 0.07, 95% CI: −0.68 to 0.03). Depression symptoms also showed significant reductions (b = −0.26, SE = 0.11, p = 0.016, 95% CI: −0.48 to −0.05). No significant changes were observed for insomnia. The SMILE app shows efficacy and potential scalability as a solution for youth with severe anxiety. These findings suggest that leveraging mobile sensing to tailor intervention delivery may enhance the smartphone-based delivery of CBT for youth with severe anxiety symptoms. Clinicaltrials.gov ( NCT06748833 ). • A smartphone app reduced anxiety in youth aged 12–21 in a randomized trial. • The app also improved depression but not insomnia symptoms. • Mobile sensing allowed personalized support with low user burden. • Benefits were maintained 12 weeks after the intervention ended. • Findings show promise for scalable youth mental health care.