Outcome Expectancies, Effects, and Mechanisms of Brief Training in Mindfulness Meditation vs. Loving-Kindness...

This study investigated the analgesic effects of a single session of mindfulness meditation (MM) and loving-kindness meditation (LKM) relative to a control. A total of 100 adults with chronic or current problematic pain completed a survey and were randomized to a 20-minute MM, LKM, or audiobook control. Co-primary outcomes of pain intensity and unpleasantness and mediators of mindfulness and self-compassion were assessed pre- and posttraining. Expectancies were assessed pretraining. Pain type (chronic vs current problematic) was a covariate. Relative to the control, higher expectancies were reported for MM and LKM (P < .001). MM (d = 0.41, P = .032) and LKM (d = 0.38, P = .027) had medium effects on pain intensity, with greater decreases than control (d = 0.05, P = .768). All conditions had small effects on unpleasantness. Mindful observing increased more within MM (d = 0.52, P = .022) and the control (d = 0.50, P = .011) than LKM (d = 0.12, P = .50); self-compassion increased more in LKM (d = 0.36, P = .042) than MM (d = 0.27, P = .201) and the control (d = 0.22, P = .249). The mediation models were nonsignificant. Pain type was a nonsignificant covariate. Overall, MM and LKM were associated with positive expectancies and small-medium pain intensity reductions, which did not differ by pain type. Although MM and LKM were associated with changes in theorized mediators, these changes did not underlie improvement.