Mediators of Mindfulness-Based Stress Reduction (MBSR): assessing the timing and sequence of change in cancer patients.

Objective: This waitlist-controlled study examined the timing of changes during Mindfulness-Based Cancer Recovery (MBCR), and explored sequential mediated effects through enhanced mindfulness and emotion regulation (ER) in a cancer population.

Methods: Patients were recruited from the MBCR program waitlist and were either registered for immediate participation (n = 135) or waiting for the next program to begin (n = 76). Participants completed self-report measures of stress symptoms, mood disturbance, mindfulness, and ER (rumination, worry, and experiential avoidance) pre-, mid- and post-MBCR or waiting period.

Results: There was a relatively early effect of MBCR on observing, nonjudging, rumination, and worry. All other measures changed later. Early changes in present-focused nonjudgmental awareness, rumination, and worry mediated the effect of MBCR on mindfulness skills such as nonreactivity later on.

Conclusions: The constructs of mindfulness and ER may overlap and changes may be mutually facilitative during MBCR. The study informs our understanding of mindfulness and ER as mechanisms of mindfulness-based interventions.