Towards a mechanistic understanding of mindfulness-based stress reduction (MBSR) using an RCT neuroimaging approach: Effects on regulating own stress in social and non-social situations

•It is not fully understood if emotion regulation (ER) effects of MBSR generalize to social settings.•In a randomized controlled trial we investigated MBSR effects using a self and social emotion regulation fMRI task.•Behaviorally, we corroborated effects on emotion regulation when regulating self but not when regulating others.•At the brain level, regulating self was accompanied by changes in parietal and insular cortices, while social emotion regulation was accompanied by changes in precuneus and parietal regions.•Cognitive reappraisal and acceptance are two emotion regulation mechanisms of MBSR in self, but not in social regulation settings.