Enhancement of Meditation Analgesia by Opioid Antagonist in Experienced Meditators
Long-term meditation practice does not rely on endogenous opioids to reduce pain, and naloxone's blockade of opioid receptors enhanced meditation analgesia; pain ratings during meditation were significantly lower under n aloxone than under saline.
Abstract
<jats:title>ABSTRACT</jats:title> <jats:sec> <jats:title>Objective</jats:title> <jats:p>Studies have consistently shown that long-term meditation practice is associated with reduced pain, but the neural mechanisms by which long-term meditation practice reduces pain remain unclear. This study tested endogenous opioid involvement in meditation analgesia associated with long-term meditation practice.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Electrical pain was induced with randomized, double-blind, cross-over administration of the opioid antagonist naloxone (0.15-mg/kg bolus dose, then 0.2-mg/kg per hour infusion dose) with 32 healthy, experienced meditation practitioners and a standardized open monitoring meditation.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Under saline, pain ratings were significantly lower during meditation (pain intensity: 6.41 ± 1.32; pain unpleasantness: 3.98 ± 2.17) than at baseline (pain intensity: 6.86 ±1.04, <jats:italic toggle="yes">t</jats:italic>(31) = 2.476, <jats:italic toggle="yes">p</jats:italic> = .019, Cohen's <jats:italic toggle="yes">d</jats:italic> = 0.46; pain unpleasantness: 4.96 ±1.75, <jats:italic toggle="yes">t</jats:italic>(31) = 3.746, <jats:italic toggle="yes">p</jats:italic> = .001, Cohen's <jats:italic toggle="yes">d</jats:italic> = 0.68), confirming the presence of meditation analgesia. Comparing saline and naloxone revealed significantly lower pain intensity (<jats:italic toggle="yes">t</jats:italic>(31) = 3.12, <jats:italic toggle="yes">p</jats:italic> = .004, <jats:italic toggle="yes">d</jats:italic> = 0.56), and pain unpleasantness (<jats:italic toggle="yes">t</jats:italic>(31) = 3.47, <jats:italic toggle="yes">p</jats:italic> = .002, <jats:italic toggle="yes">d</jats:italic> = 0.62), during meditation under naloxone (pain intensity: 5.53 ± 1.54; pain unpleasantness: 2.95 ± 1.88) than under saline (pain intensity: 6.41 ± 1.32; pain unpleasantness: 3.98 ± 2.17). Naloxone not only failed to eliminate meditation analgesia but also made meditation analgesia stronger.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Long-term meditation practice does not rely on endogenous opioids to reduce pain. Naloxone's blockade of opioid receptors <jats:italic toggle="yes">enhanced</jats:italic> meditation analgesia; pain ratings during meditation were significantly lower under naloxone than under saline. Possible biological mechanisms by which naloxone-induced opioid receptor blockade enhances meditation analgesia are discussed.</jats:p> </jats:sec>