Promoting Psychological Resilience and Well-Being in Youth With a Smartphone-Based Ecological Momentary mHealth Intervention: Secondary Analysis of a Microrandomized Trial.

Background: Ecological momentary interventions (EMIs) may be a promising tool for promoting mental well-being in youth, as they allow for targeting resilience and other protective factors in daily life. Objective: In this secondary analysis of a microrandomized trial, we explored proximal effects of a coach-guided compassion-focused smartphone-based digital training for young people applying principles and techniques of EMI (the AI4U [artificial intelligence for personalized digital mental health promotion in youth] training) on momentary outcomes of mental well-being. Methods: A convenience sample of participants aged 14 to 25 years was recruited mostly via an open-access website and completed up to 6 self-report ecological momentary assessments (EMA) per day to measure their momentary mental well-being (ie, positive affect, negative affect, and stress) during the 30-day AI4U training phase. Some EMA prompts triggered EMI components to promote their momentary resilience and well-being. Multilevel modeling was used to analyze proximal effects of initiating EMI components on outcomes assessed at the next time point, the potential moderating effect of momentary affect and stress at the time of EMI initiation, and the potential mediating effect of change in momentary resilience on the effect of EMI initiation on changes in momentary affect and stress. Results: A total of 170 individuals completed 13,059 EMA prompts and initiated 6667 EMI components. No evidence was found that momentary outcomes of mental well-being at a time point differed depending on whether an EMI component was initiated at the previous time point vs when no EMI component was initiated at the previous time point (positive affect: b=0.00, 95% CI -0.04 to 0.04; negative affect: b=-0.03, 95% CI -0.06 to 0.01; stress: b=0.01, 95% CI -0.03 to 0.05). There was no strong difference in the magnitude of this effect when momentary mental well-being at the time of EMI initiation was high vs low (positive affect: b=0.08, 95% CI 0.01 to 0.16; negative affect: b=-0.09, 95% CI -0.17 to -0.01; stress: b=0.09, 95% CI 0.01 to 0.17). Changes in momentary resilience did not mediate the effect of EMI component initiation (vs EMI component noninitiation) on changes in momentary mental well-being (positive affect: b=0.00, 95% CI -0.01 to 0.02; negative affect: b=-0.00, 95% CI -0.01 to 0.01; stress: b=0.00; 95% CI 0.00 to 0.00). Conclusions: By investigating proximal effects of EMI components, this secondary analysis analyzes proximal effects of a novel digital training using EMA, which presents an innovative approach to understanding how the digital training leads to long-term improvement of distal outcomes. The analysis contributes to research in the field of EMI by serving as a basis for future investigations on the momentary effects of EMI components, which can support the development of scalable interventions to promote mental well-being in the public.