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Category: Project

Description: This study is a quantitative synthesis of meta-analytic evidence for the effectiveness of very broadly defined positive psychological interventions (PPIs), i.e. interventions that enhance wellbeing through pathways consistent with positive psychology theory. The definition covers a wide range of PPIs including single and multi-element PPI programs as well as mindfulness, mind-body, and physical exercise-based interventions. A mega-analysis of meta-analyses of studies which evaluated PPIs defined in this way was registered with Prospero (CRD42020160217) and conducted. Five databases were searched. 198 meta-analyses involving 4,063 primary studies and 501,335 participants were selected for review. Using AMSTAR-2 criteria, selected meta-analyses were found to be of moderate or high quality. At post-intervention, PPIs had a significant small to medium effect on wellbeing, g = 0.34 [0.29, 0.39], QoL, g = 0.41 [0.37, 0.45], strengths, g = 0.42 [0.39, 0.45], depression, g = 0.42 [0.37, 0.47], anxiety, g = 0.41 [0.34, 0.48], and stress, g = 0.42 [0.36, 0.48]. Gains were partially maintained at 7.5 months follow-up. Mind-body PPIs such as yoga and tai chi were particularly effective. Individuals who engaged in longer, face-to-face programs benefited most. Larger effect sizes occurred in meta-analyses of trials with inactive rather than active control groups and in meta-analyses of lower methodological quality. This mega-analysis shows that PPIs have an extensive evidence base supporting their effectiveness, especially longer, face-to-face PPI programs that incorporate mind-body interventions. Further mega-analytic research on PPI change mechanisms is required.