Timely intervention: Efficacy of a depression symptom monitoring smartphone app to deliver psychological intervention at time of greatest need

Arm 1: self-guided use of a smartphone app-based intervention for depression. This group is given access to the intervention materials (via app), with the instructions to complete each of the 12 x 30 minute modules in sequence. It is emphasized that the modules are designed to be paced at one per week. The treatment material consists of six modules based on 3rd Wave Cognitive and Behavioural approaches to treat negative moods and build personal resilience: (1) Acceptance and Commitment Therapy (ACT) to identify personal values (2) Cognitive Behaviour Therapy (CBT) to uncover and dispute unhelpful thinking styles and their underlying assumptions, (3) Mindfulness Based Cognitive Behavioural Therapy (MCBT) to learn to accept negative thoughts without judgment, (4) resilience building to learn to maintain healthy levels of self-esteem, optimism, and to savour acts of kindness and gratitude, (5) Behavioural Activation to increase exposure to positive situations that provide meaning and/or pleasure and, (6) Troubleshooting/Relapse prevention. Arm 2: app-enhanced use of a smartphone app-based intervention for depression. This group is also given access to the intervention materials, with the same instructions for self-guided use (i.e., complete one module per week for 12 weeks). However, they are also informed that, based on their scores on the brief app surveys (given up to four times per day, measuring current mood state), they will be invited to undertake brief, additional content (top-up activities) at times of greatest need (i.e., when their depressive mood state scores are elevated they may be recommended to complete a brief relaxation task). These top-up activities are similar to the activities they receive in the online training, but are prompted by scores deemed at risk by the app surveys. Please note, these top-up activities are additional to, rather than substitutes for, the 12 weeks of module content, and participants are encouraged to continue to progress through the 12 modules at the same pace as recommended for Arm 1 participants (regardless of how many times they may engage in top-up activities). Both groups will have access to the intervention content for 12 weeks. Adherence and usage is monitored by the app for both groups.