Mindfulness-based stress reduction (MBSR) enhances short-term psychological health in clinical and non-clinical samples, whereas studies examining long-term effects are scarce. This study examined whether the effects of a 7-week MBSR programme on mental health persisted at 2- and 4-year follow-up and explored possible mechanisms of effect.
In a two-site randomised controlled trial, 288 medical and psychology students were allocated to an MBSR intervention (n = 144) or a no-treatment control group (n = 144). During the 4-year follow-up period, the MBSR group was offered 90-min booster sessions semi-annually. The primary outcome measures were mental distress (General Health Questionnaire (GHQ)) and subjective well-being (SWB); these were measured at baseline (T0) and post-intervention follow-up at 1 month (T1), 2 years (T1) and again at 4 years (T3). Secondary outcomes included coping, mindfulness and meditation practice.
At 4-year follow-up, the MBSR group showed significantly better scores on mental distress, mindfulness, avoidance coping and problem-focused coping (Cohen’s d = 0.23–0.42). Meditation practice positively predicted long-term mindfulness scores. Short-term effects in mindfulness scores mediated long-term intervention effects in mental distress and coping. However, reversed mediation was also observed (i.e. changes in outcome mediating long-term mindfulness scores), and this indicates that initial changes in outcome and mindfulness are intrinsically intertwined and may both influence long-term effects. Small post-intervention effects on well-being and seeking social support did not persist at follow-up.
MBSR fostered enduring effects on mental distress and coping in medical and psychology students 4 years post-intervention.