Posted 12.15.2015 | by AMRA

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Pain is a common and often complex medical complaint. Previous studies demonstrate the possible pain-reducing effects of mindfulness-based interventions, but little is known about how these interventions actually work. Is mindful awareness their “active ingredient,” or is it slowed breathing, or even just the expectancy of a benefit?

Zeidan et al. [The Journal of Neuroscience] compared the changes in pain sensitivity resulting from a genuine mindfulness intervention with the changes resulting from a sham mindfulness intervention and two other control conditions. Participants rated their subjective pain in response to an unpleasant heat stimulus while undergoing functional Magnetic Resonance Imaging (fMRI). They also completed the Freiburg Mindfulness Inventory prior to initial training and at the end of their final fMRI session.

A racially diverse cohort of 75 healthy, meditation-naive young adult men and women were randomly assigned to either mindfulness meditation, a sham mindfulness meditation, placebo conditioning, or listening to an audio book. Genuine mindfulness meditation training consisted of four 20-minute sessions involving a breath-focused sitting meditation along with didactic instruction in non-judgmental attention. Sham meditation training involved four 20-minute sessions of alleged “mindfulness meditation” that consisted of merely sitting upright and taking a deep breath every few minutes without any didactic instruction.

Placebo conditioning involved four 20-minute conditioning sessions in which an alleged “analgesic cream” (in actuality, only petrolatum jelly) was applied to the skin and participants were exposed to a series of heat stimuli that were covertly and progressively lowered in temperature over the course of the sessions. Control participants listen to four 20-minute audio recordings from a book.

In a separate final assessment session after training completion, all the participants underwent fMRI scanning while exposed to an unpleasant heat stimulus. This was done both before and after using the techniques (e.g., real or sham meditation or placebo) they had trained on. Participants rated their pain intensity and unpleasantness in response to the heat stimulus on a 10-point scale.

Mindfulness meditation produced significantly greater decreases in pain intensity (-27%) than sham meditation (-8%) or placebo (-11%), as well as significantly greater decreases in pain unpleasantness (-44%) than sham meditation (-27%) or placebo (-13%). The control group, in contrast, experienced increased pain intensity (+14%) and unpleasantness (+18%). Mindfulness meditators increased their mindfulness scores by 16%, a significantly greater increase than either the controls (2%), sham meditators (.03%) or the placebo group (3%).

Brain imaging results showed that mindfulness participants had significantly greater left dorsolateral prefrontal cortex, thalamus, and periaqueductal gray matter deactivation and significantly greater anterior cingulate cortex, bilateral anterior insula, and putamen activation than controls, sham meditators, and placebo users. These differences reflect a deactivation of low-level sensory and pain processing areas, and increased activation of areas related to the cognitive control of pain.

Mindfulness meditation also significantly reduced global cerebral blood flow (-21%) compared to sham meditation (-7%), placebo (-2%) or the control condition (-4%). Sham meditation pain reduction was significantly correlated with lowered respiration rate, whereas mindfulness pain relief was not, suggesting that sham meditation reduces pain via the relaxation response, whereas mindfulness meditation reduces pain via cognitive control.

This elegantly designed study demonstrates that mindfulness-based acute pain reduction is both greater than and distinct from placebo-based or relaxation-based acute pain reduction. Mindfulness meditation’s unique, distinctive pattern of brain activation strengthens the case that mindfulness itself is an active ingredient over and above any relaxation or expectancy components.

Reference:

Zeidan, F., Emerson, N. M., Farris, S. R., Ray, J. N., Jung, Y., McHaffie, J. G., & Coghill, R. C. (2015). Mindfulness meditation-based pain relief employs different neural mechanisms than placebo and sham mindfulness meditation-induced analgesia. The Journal of Neuroscience, 35(46), 15307-15325.

[Link to abstract]