My Best Self in the Past or Future: A Randomized Controlled Trial Examining Adherence, Engagement, Age and Mental Health in a Mobile-based BPS Intervention

This study examined the specific and generic mechanisms of change in a. Best Possible Self (BPS) intervention delivered by an app. The effect of temporal frame, adherence, engagement and age on the effectiveness of the intervention was examined. Method. A total of 290 participants were randomized across three conditions: the Best Possible Self (BPS), the Best Past Self and Best Possible Self (BPAS/BPS) or an active control condition. Mental health was assessed at baseline (T0), one week after the start of the intervention (T1), two weeks immediately after the intervention (T2) and at a four-week follow-up (T3). Adherence was indicated by daily app use, and engagement was measured at T1 and T2. Results. Four hypotheses were tested: (1) ANCOVAs showed that the BPS condition had some beneficial effects on mental health, whereas the BPAS/BPS condition was not more effective than the control condition; (2) regression analyses showed that engagement, but not adherence, was a significant predictor of app effectiveness; (3) mediation analysis showed that the BPS condition was more engaging than the BPAS/BPS condition which explained the positive effect on life satisfaction, (4) moderated mediation analyses showed that visualizing the best possible self in the past was not more effective for older participants, nor did age influence engagement levels. Conclusion. Visualizing a BPS using an app might be an efficient way to improve the mental health of many on a small scale. The app should be designed to be engaging.