Mediators of a Mindfulness-Based Intervention for Younger Breast Cancer Survivors: Effects on Depressive Symptoms.

OBJECTIVE: Depression is associated with poor outcomes in breast cancer patients, with higher prevalence among younger women. While mindfulness-based interventions (MBIs) have demonstrated therapeutic effects, the mechanisms of intervention effects are poorly understood. We investigated whether rumination, self-kindness, intrusive thoughts about cancer, cancer-related worry, or meaning and peace mediated intervention effects of a MBI, Mindful Awareness Practices (MAPs), on depressive symptoms. Additionally, we explored the same variables as mediators of a psychoeducation program, Survivorship Education (SE).

METHODS: Women diagnosed with Stage 0-III breast cancer at age < 50 were randomized to 6 weeks of MAPs (n = 85), SE (n = 81), or wait-list control (WLC; n = 81). During pre-, post-intervention, and 6-month follow-up (FU), we assessed depressive symptoms, rumination, self-kindness, intrusive thoughts, worry, and meaning and peace.

RESULTS: MAPs and SE significantly reduced depressive symptoms at post-intervention, and reductions remained through 6-month FU for MAPs. Models revealed that reductions in rumination (β = -0.68, 95% CI [-1.64, -0.07]) and intrusive thoughts (β = 1.17, 95% CI [-2.17, -0.37]) and improvements in self-kindness (β = -1.09, 95% CI [-2.37, -0.28]) and meaning and peace (β = -1.09, 95% CI [-3.16, -0.56]) mediated MAPs' effects at all time points. Reductions in worry (β = -1.34, 95% CI [-2.47, -0.45]) mediated effects at post-intervention only. Worry and intrusive thoughts mediated SE effects at post-intervention and 6-month FU, respectively.

CONCLUSIONS: Findings identified depression-relevant mediators of MAPs' effects, expanding the understanding of MBI mechanisms. Results highlight pathways that could be leveraged to optimize intervention outcomes.