Objectives The objective of this study was to evaluate the perceived scope of effect across users of a web-based cognitive-behavioral therapeutic (CBT) mobile application for treatment of anxiety and mild depression (N=4711). In addition, the study sought to determine the potential preliminary effectiveness of the application in delivering self-administered CBT.

Method Participants (N=4711) were recruited from the users of the mobile application and were divided into three groups according to the length of use of the application. There was a significant difference in the scope of perceived outcomes between the first and the second group: Cohen's d= 0.56, 95%CI[0.49-0.62] and between first and third group Cohen's d= 0.80, 95%CI[0.72-0.88]. No significant differences were detected between second and third groups. The fact that many users spontaneously referred to a high level of psychological benefits in open questions suggests subjects perceived these as a notable benefit of using the method.

Results Participants in group one experienced a limited scope of effect compared to the medium and long-standing users in groups two and three. Subjects in these groups reported perceiving tangible changes in a wider range of areas as a result of usage, particularly regarding reduced sympthoms of depression and anxiety. This study also explores the evidence base and novel research opportunities connected to the application. Collected data provides useful insights into how subjects typically interact with this application, a specific feature of which is that it can dynamically adapt to user's goals and needs.

Conclusions The application appear to offer potential as an engaging and effective way to deliver CBT. The effect sizes should be interpreted cautiously in light of the motivated, self-selected sample. Nevertheless, it may provide a convenient method for accessing support, especially in Russia, where a very low proportion of individuals with depression and anxiety disorders receive adequate care due to a range of obstacles that prevent or limit access to treatment.