Background:
Cognitive behavioral therapy (CBT) in its basic principle has developed itself as a stand-alone, substantial method of therapy. With effective application in therapy for a range of mental health issues, the spread of CBT methods to Web-based therapy sources is evident. The development of mobile phone apps using CBT principles is increasing within the research area. Despite the move to Web-based methods of therapy, it is argued that these methods lack the same efficacy of face-to-face therapy sessions.

Objective:
The aim of this review was to assess extent research findings with regard to the effectiveness
of CBT-related mobile health (mHealth) apps. By assessing only studies employing a randomized controlled
trial design, the review aimed to determine app efficacy within the highly regarded method of
investigation.

Methods:
A comprehensive literature search was conducted across several databases. Search results were
filtered, and results were subject to strict inclusion and exclusion criteria because of the nature of the
review. Where possible, analysis of effect size was calculated and results reported.

Results:
A total of 8 studies investigating the effectiveness of mHealth CBT-related apps across a range of
mental health issues were reviewed. Three studies used the app against a control group, and 5 studies
used the app intervention against another form of treatment or intervention. A range of effect sizes were
seen across all included studies (d=−0.13 to 1.83; 0.03-1.44), with the largest effects often being seen when comparing the data from pre- to posttest for the app engaged group.

Conclusions:
The studies reviewed support the use of mHealth apps containing CBT principles for a range
of mental health issues. However, the effectiveness over longer time periods should be
assessed. Researchers and professionals should seek to collaborate effectively when creating new apps
to enhance their effectiveness as a treatment for the general public.