Mindfulness-based stress reduction (MBSR) for fibromyalgia patients: The role of pain cognitions as mechanisms of change.

Fibromyalgia (FM) is a pain condition characterized by physical and psychological difficulties. This randomized controlled trial aimed to evaluate the effects of a mindfulness-based stress reduction (MBSR) on FM patients and identify the role of two pain cognitions: psychological inflexibility in pain (PIPS) and pain catastrophizing (PCS), as mechanisms of change. 95 FM patients (Mean ± SD: 49.18 ± 13.26 years) were randomly assigned to MBSR group therapy (n = 49) or a waitlist (WL) control group (n = 46). An adapted MBSR protocol for FM was employed. A series of measures were taken, covering FM symptoms, depression, perceived stress (PSS), PIPS and PCS. Three measurements were conducted: pre-intervention, post-intervention and 6-months follow up. Compared to WL controls, the MBSR group showed greater improvements in FM symptoms (F(1,78) = 2.81, p < 0.05), PSS (F(1,78) = 4.38, p < 0.05) and Depression (F(1,78) = 21.12, p < 0.001), with mostly medium effect sizes. Improvements in PSS (F(2,68) = 7.75, p < 0.05) and depression (F(2,68) = 15.68, p < 0.05) remained stable over six months. The effect of MBSR on FM and PSS was mediated by one's reported change in PIPS. The effect of MBSR on depression was mediated by one's reported change in PCS. These results reveal the significant therapeutic potential of MBSR for FM patients, due to the emphasis on non-judging and acceptance of negative inner states. Furthermore, this research identified two important pain-related cognitions as mechanisms of change, suggesting that MBSR contributes to cognitive change, which enables the reduction of physical and psychological distress. NCT04304664. • Mindfulness-based therapy improves FM symptoms, perceived stress and depression. • Psychological Inflexibility in Pain and Pain Catastrophizing are important mechanisms of change in MBSR for FM. • A tailor-made MBSR protocol for FM was developed for this trial, in order to meet patients' specific needs and challenges.