Personality change through mindfulness-based interventions: A preregistered systematic review and meta-analysis

Mindfulness-based interventions (MBIs) lead to improvements in mental health, and also increase trait mindfulness. Yet, trait mindfulness shows definitional and empirical overlaps with the personality dimension of neuroticism which is linked to mental health and is malleable through interventions as well. This meta-analysis examined whether previously reported associations between increases in self-reported trait mindfulness and mental health in MBIs, as well as in non-MBIs and treatment-as-usual (TAU) and waitlist controls, are mediated through concomitant changes in neuroticism on the between-study level. Data of 45 intervention studies (39 randomized controlled trials; total N = 2913) were investigated with three-level meta-analysis and the causal steps approach. Change in neuroticism mediated change in trait mindfulness and fully accounted for its mediational effects on mental health. Similar associative patterns were found for the active and TAU and waitlist control groups as well. Accounting for small-study effects did not alter this pattern of results. The findings highlight the relevance of neuroticism for intervention research and may explain previously observed apparent effects of trait mindfulness in non-MBIs and TAU and waitlist controls on mental health. The construct of trait mindfulness may need conceptual reconsideration and resharpening, and the investigation of personality change should be intensified in intervention research. Plain language summary Mindfulness-based interventions (MBIs) may not only improve mental health, but also the extent individuals are mindful in their daily lives (i.e., trait mindfulness). Previous research suggested that this increase in trait mindfulness explains the beneficial effects of MBIs on mental health. Paradoxically, other active, non-MBI, treatments increase trait mindfulness as well. The present research presents evidence that MBIs and other active treatments also decrease the tendency to experience negative emotionality and interpret stimuli in a more negative way (i.e., the personality trait of neuroticism). Neuroticism has close links with mental health. Changes in this more general personality trait thus may alternatively account for the beneficial effects of MBIs (and other active treatments), rather than increases in trait mindfulness in particular. This may explain otherwise paradoxical observations and highlights problems with the construct and measurement of trait mindfulness. Neuroticism may