Abstract
Background: Technological advancements make it possible to deliver depression interventions via smartphone applications ("Apps"), including those that deliver content "just-in-time" (e.g., in response to acute negative mood states). This study examined whether an app-based just-in-time intervention (ImproveYourMood+) decreased depressive symptoms, and whether the following features were related to symptom improvement: micro-intervention content, mood monitoring, and just-in-time prompts to use content.Methods: Participants (n = 235) from the general population who self-identified as wanting to improve their negative mood were randomised to a waitlist control group (n = 55) or one of three intervention groups: MoodTracker (monitoring-only, n = 58), ImproveYourMood (monitoring and content; n = 62), or ImproveYourMood+ (monitoring, content, and prompts; n = 60). The active intervention phase was 3 weeks. Depressive and anxiety symptoms, and negative automatic thoughts were assessed at baseline, immediately post-intervention, and one month following post-intervention.Results: Linear mixed modelling revealed greater declines over time in depressive and anxiety symptoms and negative automatic thoughts for the ImproveYourMood group (standardized mean differences [SMDs] ranged from .32 to .40) and improves for the ImproveYourMood+ group for negative automatic thoughts (SMDs ≥ .37) compared to the waitlist control group. No between-group differences were observed between the MoodTracker and control groups (SMDs = .04-.23). User experience appeared to be superior in more comprehensive/multi-modal versions.Limitations: The study employed a naturalistic design, whereby participants self-selected to utilise the program, did not complete eligibility assessments, and did not receive compensation. The study therefore attained considerable drop-out rate (~50% by the follow-up timepoints), potentially reflecting the usage patterns of real-world mental health apps.Conclusions: The findings suggest that micro-interventions can be an effective way to reduce depressive symptoms both in the moment and 1-2 months later. Integration of micro-interventions with full treatment programs is a viable next step in micro-intervention research. [ABSTRACT FROM AUTHOR]