Potential treatment mechanisms in a mindfulness-based intervention for people with progressive multiple sclerosis.

Objectives: To explore putative mediators of a mindfulness-based intervention to decrease distress in people with multiple sclerosis (MS) and to explore the patients' perspectives on this intervention.

Design: We used an explanatory mixed methods design incorporating quantitative data from a pilot randomized control trial and a qualitative interview study with people who completed the mindfulness intervention.

Methods: People with MS (n = 40) completed standardized measures of distress (outcome), and acceptance, decentring, self-compassion, and self-efficacy (potential mediators). Semi-structured interviews (n = 15) of patients' experiences of the mindfulness intervention were analysed deductively and inductively.

Results: Decentring post-intervention explained 13% of the 3-month change in distress and between 27% and 31% of concurrent changes in distress. Acceptance changed only slightly, and as a result, the indirect effect accounts for only 2% of future distress and between 3% and 11% of concurrent distress. Qualitative data showed that acceptance and self-compassion needed more time to develop, whereas decentring could be implemented readily after being introduced in the sessions. Self-efficacy also had a large mediating effect. Participants in their interviews talked about group dynamics and prior expectations as essential elements that determine their engagement with the course and their level of satisfaction.

Conclusions: Mindfulness interventions for people with a chronic progressive condition may benefit from focusing on helping them to accept daily challenges and teach them to recognize their thoughts and feelings, allowing time for acceptance and self-compassion to develop. Group dynamics also play a fundamental role in the success of the mindfulness interventions. Statement of Contribution What is already known on this subject? Mindfulness courses improve psychological well-being for people with chronic conditions. Mindfulness courses have been successful in improving psychological well-being and symptom management for people with multiple sclerosis but we do not know how these courses work. What does this study add? Decentering and self-efficacy appear to be key mechanisms leading to reduced distress. Acceptance and self-compassion may need more time and practice to develop. Group dynamics and expectations of the mindfulness courses were also important elements of mindfulness.