Standalone smartphone CBT-based Ecological Momentary Interventions to increase mental health - a narrative review

Introduction: A growing number of psychological interventions are delivered via smartphone with the aim to increase the efficacy and effectiveness of these treatments and provide scalable access to interventions for improving mental health. Most of the scientifically tested apps are based on cognitive behavioural therapy principles which are considered as a gold standard for the treatment of many mental health problems. Objective: This review aimed to investigate standalone smartphone-based ‘ecological momentary interventions’ (EMIs) to improve mental health, that were built based on principles derived from cognitive behavioural therapy (CBT). Methods: We searched MEDLINE, PsycINFO, Embase and PubMed databases for peer-reviewed studies published between 1st January 2007 and 15th January 2020. We included studies with a focus on standalone app-based approaches to improve mental health and their feasibility, and/or efficacy and/or effectiveness. Both within- and between-group designs and studies with both healthy and clinical samples were included. Blended interventions, e.g., app-based treatments in combination with psychotherapy, were not included. Selected studies were evaluated in terms of their design, i.e., choice of the control condition, sample characteristics, EMI content, EMI delivery characteristics, feasibility, efficacy and effectiveness. The latter was defined in terms of improvement in primary outcomes used in the studies. Results: A total of 26 studies were selected. The results show that EMIs based on CBT principles can be successfully delivered, significantly increase well-being among users, and reduce mental health symptoms. Standalone EMIs were rated as helpful (m=70.8%), and outcomes were satisfying by users (m=72.6%). Conclusions: Study quality was heterogeneous, and feasibility was often not reported in the reviewed studies, hence limiting the conclusions that can be drawn from the existing data. Together, the studies show that EMIs may help increase mental health and thus support individuals in their daily life. Such EMIs provide readily available, scalable and evidence-based mental health support. These characteristics appear crucial in the context of a global crisis, such as the COVID-19 pandemic, but may also help reduce personal and economic costs of mental health impairment beyond this situation or in the context of potential future pandemics.