Brief Use of Behavioral Activation Features Predicts Benefits of Self-help App on Depression Symptoms: Secondary Analysis of a Selective Prevention Trial in Young People

Objective: To explore which CBT self-help app usage predicted depression during a selective prevention trial. Method: A recent controlled trial (ECoWeB-PREVENT) randomised young people aged 16- 22, at increased risk for depression because of elevated worry/rumination, negative appraisals, and/or rejection sensitivity but without past or current history of major depression, to apps that provided self-monitoring, self-monitoring plus CBT self-help, or self-monitoring plus emotional competency self-help. Self-help included coping strategies for moment-by- moment use (Tools) and self-learning/planning exercises (Challenges). On the primary outcome (depression, PHQ-9) at 3-months follow-up (primary endpoint), only the CBT app outperformed self-monitoring. In this secondary analysis, only data from participants who used the CBT or self-monitoring apps at least once was analysed to test what app use predicted change in depression from baseline to 3 months. Results: Of the original 1262 participants (79% female), 558 were included (CBT, baseline, n = 273, PHQ-9: M=7.48, SD=3.9; 3-months, N =163, PHQ-9: M =8.83, SD=4.92; Self- monitoring, baseline, n=285, PHQ-9: M=7.45, SD=4.26; 3-months, N=183, PHQ-9: M=7.48, SD=3.9). Neither total app use, self-monitoring, nor use of Tools predicted change in depression (all p’s >.05). Frequency of use of Challenges predicted lower depression symptoms and caseness at three months (β =-0.28, 95%CI -0.53 to -0.03, p =.029). Specifically, use of Behavioral Activation Challenges mediated the effects of the CBT app on depression over 3-months (β =-0.59, 95% CI: -1.13 to -0.05, p =.03). Conclusions: Brief psychoeducation about behavioral activation principles in an app may protect young people from depression over 3-months, even when only used once.