Contents lists available at ScienceDirect Behaviour Research and Therapy journal homepage: www.elsevier.com/locate/brat A randomized controlled trial of three smartphone apps for enhancing public mental health David Bakker a,* , Nikolaos Kazantzis a,b , Debra Rickwood c , Nikki Rickard a,d a School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Australia b Cognitive Behaviour Therapy Research Unit, Monash University, Australia c Psychology Department, Faculty of Health, University of Canberra, Australia d Centre for Positive Psychology, University of Melbourne, Australia ARTICLE INFO Keywords: Technology Anxiety Depression Cognitive behavioural therapy Randomized controlled trial Mobile ABSTRACT Many smartphone applications (apps) for mental health (MHapps) are available to the public. However, few have been the subject of a randomized controlled trial (RCT), and the change processes that are hypothesized to mediate claimed effects have not been previously studied. This RCT compared the efficacy of three publicly available MHapps to a waitlist control condition in a community sample, in which no MHapp was provided. The three MHapps included cognitive behavioural therapy (CBT) toolkit app MoodKit, mood tracking app MoodPrism, and CBT strategy app MoodMission. Participants were randomly allocated to each condition, completed a baseline assessment, downloaded their allocated MHapp, and completed a second assessment 30 days later, with n = 226 included in final analyses (81% female; M age = 34 years). Compared to the control condition, all MHapp groups experienced increases in mental wellbeing, MoodKit and MoodMission groups experienced decreases in depression, and no groups experienced effects on anxiety. Mediated regressions re- vealed that increasing coping self-efficacy, rather than emotional self-awareness or mental health literacy, was the underlying process contributing to effects on mental health for all three MHapps. MHapps appear to be an effective solution for improving public mental health, notably by improving users' confidence in their ability to cope. 1. Introduction Depression and anxiety disorders are highly prevalent, with de- pression being the leading cause of global disease burden and disability (World Health Organization, 2017). However, treatment access is generally poor. While 18.1% of adults in the United States experience an anxiety disorder every year, only 36.9% received treatment (Kessler, Chiu, Demler, Merikangas, & Walters, 2005), and 4.3% are diagnosed with a Major Depressive Episode, with 65.3% receiving treatment (Ahrnsbrak, Bose, Hedden, Lipari, & Park-Lee, 2017). Self-guided preventative interventions, classified under the broad term “low-intensity interventions”, use fewer economic and clinical resources which are predominantly self-guided and can be used for preventative purposes (Bennett-Levy, Richards, & Farrand, 2010). Ex- amples include workbooks, websites, and digital therapies, which can be efficient and effective when core dimensions in psychopathology common to both anxiety and depression are targeted (Barlow et al., 2017). Self-guided interventions are part of a stepped-care approach, which prioritizes “high intensity” psychological interventions (e.g. psychotherapy and psychoactive medications) for those with the greatest distress and clinical need, and “low intensity interventions” for those who may not require one-on-one clinician support (van Straten, Hill, Richards, & Cuijpers, 2015). However, emotional disorders con- tinue to have high prevalence and represent significant public health and global economic burden (Whiteford et al., 2013). Low-intensity interventions show promise (Williams & Martinez, 2008), but new modes of delivery including those that do not require clinician support are required to increase their accessibility. Thus, smartphone applica- tions (apps) for mental health (MHapps) represent a compelling new delivery mode for self-guided psychological interventions in prevention and stepped-care. MHapps have a number of advantages over traditional intervention paradigms, including financial affordability, anonymity, context and geographic flexibility, and ease of feedback data collection for the in- tervention developers (Vogl, Ratnaike, Ivancic, Rowley, & Chandy, 2016). However, as more MHapps become available to the public, so https://doi.org/10.1016/j.brat.2018.08.003 Received 7 February 2018; Received in revised form 5 August 2018; Accepted 10 August 2018 * Corresponding author. E-mail address: david.bakker@monash.edu (D. Bakker). Behaviour Research and Therapy 109 (2018) 75–83 Available online 11 August 2018 0005-7967/ © 2018 Elsevier Ltd. All rights reserved. T