A synthesis of RCTs on psychological interventions fostering strengths and virtues: Evidence from 21 systematic reviews.

Research on mental health advocates the cultivation of character strengths to enhance well-being. Existing meta-analyses support positive correlations between strengths and well-being, and an increasing number of randomized controlled trials (RCTs) have assessed the effects of interventions aimed at cultivating them. This pre-registered multiple systematic review of RCTs aims to map and synthesize evidence from these trials regarding the overall impact of such interventions on strengths and well-being. Based on Peterson and Seligman's Virtues in Action model, which groups 24 character strengths under 6 virtues as latent variables, we conducted searches for each character strength (21 in total), across four specialized databases, including gray literature. The included RCTs assessed the impact of virtue-based interventions with adult participants in studies including baseline and post-intervention measures of the targeted strength and well-being. After reviewing 61,479 abstracts, 162 RCTs were included representing 15 strengths grouped into the six virtues among 33,032 participants. In contrast, the interventions with the best evidence for increasing strengths and well-being were those that enhanced kindness, humor, hope, perspective, and gratitude. Our review revealed that there is a relative paucity of RCT studies in the field and a need to include robust outcome measures. While there is relatively robust evidence of the efficacy of RCTs to enhance certain character strengths and associated well-being, there is still insufficient evidence on the efficacy of most of the 24 strengths of Peterson and Seligman's model. We discuss implications of the findings and recommend guidelines for future research.