title: How do mindfulness-based cognitive therapy and mindfulness-based stress reduction improve mental health and wellbeing? A systematic review and meta-analysis of mediation studies.
abstract: Given the extensive evidence base for the efficacy of mindfulness-based stress reduction (MBSR) and mindfulness-based cognitive therapy (MBCT), researchers have started to explore the mechanisms underlying their therapeutic effects on psychological outcomes, using methods of mediation analysis. No known studies have systematically reviewed and statistically integrated mediation studies in this field. The present study aimed to systematically review mediation studies in the literature on mindfulness-based interventions (MBIs), to identify potential psychological mechanisms underlying MBCT and MBSR's effects on psychological functioning and wellbeing, and evaluate the strength and consistency of evidence for each mechanism. For the identified mechanisms with sufficient evidence, quantitative synthesis using two-stage meta-analytic structural equation modelling (TSSEM) was used to examine whether these mechanisms mediate the impact of MBIs on clinical outcomes. This review identified strong, consistent evidence for cognitive and emotional reactivity, moderate and consistent evidence for mindfulness, rumination, and worry, and preliminary but insufficient evidence for self-compassion and psychological flexibility as mechanisms underlying MBIs. TSSEM demonstrated evidence for mindfulness, rumination and worry as significant mediators of the effects of MBIs on mental health outcomes. Most reviewed mediation studies have several key methodological shortcomings which preclude robust conclusions regarding mediation. However, they provide important groundwork on which future studies could build.
authors.affiliation: School of Psychology, University of Sussex, Falmer, East Sussex, BN1 9QH, UK; Sussex Mindfulness Centre, Research and Development Directorate, Hove, BN3 7HZ, UK.
authors.forename: Jenny
authors.initials: J
authors.lastname: Gu
authors.affiliation: Sussex Mindfulness Centre, Research and Development Directorate, Hove, BN3 7HZ, UK; Sussex Partnership NHS Foundation Trust, Hove, BN3 7HZ, UK.
authors.forename: Clara
authors.initials: C
authors.lastname: Strauss
authors.affiliation: School of Psychology, University of Sussex, Falmer, East Sussex, BN1 9QH, UK.
authors.forename: Rod
authors.initials: R
authors.lastname: Bond
authors.affiliation: School of Psychology, University of Sussex, Falmer, East Sussex, BN1 9QH, UK; Sussex Mindfulness Centre, Research and Development Directorate, Hove, BN3 7HZ, UK. Electronic address: kate.cavanagh@sussex.ac.uk.
authors.forename: Kate
authors.initials: K
authors.lastname: Cavanagh
mesh_terms: D006801:Humans; D008603:Mental Health; D064866:Mindfulness; D013315:Stress, Psychological / Q000517:prevention & control / Q000628:therapy*; D016896:Treatment Outcome; D015928:Cognitive Behavioral Therapy
keywords: Mechanisms; Mediation; Mental health; Meta-analysis; Mindfulness; Structural equation modelling