Mindfulness-Meditation-Based Pain Relief Is Not Mediated by Endogenous Opioids

Abstract

Mindfulness meditation, a cognitive practice premised on sustaining nonjudgmental awareness of arising sensory events, reliably attenuates pain. Mindfulness meditation activates multiple brain regions that contain a high expression of opioid receptors. However, it is unknown whether mindfulness-meditation-based analgesia is mediated by endogenous opioids. The present double-blind, randomized study examined behavioral pain responses in healthy human volunteers during mindfulness meditation and a nonmanipulation control condition in response to noxious heat and intravenous administration of the opioid antagonist naloxone (0.15 mg/kg bolus + 0.1 mg/kg/h infusion) or saline placebo. Meditation during saline infusion significantly reduced pain intensity and unpleasantness ratings when compared to the control + saline group. However, naloxone infusion failed to reverse meditation-induced analgesia. There were no significant differences in pain intensity or pain unpleasantness reductions between the meditation + naloxone and the meditation + saline groups. Furthermore, mindfulness meditation during naloxone produced significantly greater reductions in pain intensity and unpleasantness than the control groups. These findings demonstrate that mindfulness meditation does not rely on endogenous opioidergic mechanisms to reduce pain.

Significance statement: Endogenous opioids have been repeatedly shown to be involved in the cognitive inhibition of pain. Mindfulness meditation, a practice premised on directing nonjudgmental attention to arising sensory events, reduces pain by engaging mechanisms supporting the cognitive control of pain. However, it remains unknown if mindfulness-meditation-based analgesia is mediated by opioids, an important consideration for using meditation to treat chronic pain. To address this question, the present study examined pain reports during meditation in response to noxious heat and administration of the opioid antagonist naloxone and placebo saline. The results demonstrate that meditation-based pain relief does not require endogenous opioids. Therefore, the treatment of chronic pain may be more effective with meditation due to a lack of cross-tolerance with opiate-based medications.

Keywords: cognitive; mindfulness meditation; naloxone; opioid; pain.

Figure 1.

Psychophysical pain intensity ratings (±95% confidence intervals). Meditation during saline (meditation + saline) infusion significantly (p < 0.001) reduced pain intensity and unpleasantness ratings compared with rest and the control and saline (control + saline) group. Importantly, naloxone failed to reverse meditation-induced analgesia. Meditation during naloxone administration (meditation + naloxone) significantly (p < 0.001) reduced pain intensity ratings compared with rest, the control + saline group, and the control and naloxone (control + naloxone) groups. There were no significant differences in pain intensity reductions (p = 0.69) between the meditation + saline and the meditation + naloxone groups.

Figure 2.

Psychophysical pain unpleasantness ratings (±95% confidence intervals). Meditation during saline (meditation + saline) infusion significantly (p < 0.001) reduced pain unpleasantness compared with rest and the control and saline (control + saline) group. Naloxone did not reverse meditation-induced pain relief. Meditation during naloxone administration (meditation + naloxone) significantly (p < 0.001) reduced pain unpleasantness ratings compared with rest, the control + saline group and the control and naloxone (control + naloxone) groups. There were also no significant differences in pain intensity reductions (p = 0.75) between the meditation + saline and the meditation + naloxone groups.