Mindfulness physical therapy, pain management, rehabilitation

Meaning and Modulation of Pain

The mind can have a powerful influence on the experience of pain. I sometimes describe the following study to patients to demonstrate the influence of attitude on pain tolerance and endogenous pain modulation. Benedetti and colleagues induced ischemic arm pain in healthy volunteers by inflating a sphygmomanometer, placed around the upper arm, to a pressure of 300 mm Hg.1 Subjects were instructed to squeeze a hand spring exerciser 12 times and to tolerate the pain for as long as possible. One group was informed the task would be painful. Conversely, a second group was told that the ischemic pain would be beneficial to the muscles and the longer the task was tolerated, the larger the beneficial effects would be. The mean pain tolerance, expressed in minutes, for the first group was 14.1 minutes whereas for the second group, told the task was beneficial, was 23.5 minutes.

Subjects performed the task 4 times on 4 nonconsecutive days. A control group underwent the activity in the absence of any drug treatment and experienced no significant variation in pain tolerance over the 4 trials. The other groups received no drug treatment on one occasion and, on the other 3, received either an opioid antagonist, naltrexone, a cannabinoid antagonist, rimonabant, or both. Results indicated that the increase in pain tolerance by the group who perceived the task beneficial was partially blocked by naltrexone alone and rimonabant alone. When the opioid and cannabinoid antagonists were administered together, the increase in pain tolerance by this group was eliminated completely. These results suggest that endogenous opioid and cannabinoid systems were co-activated when subjects expected beneficial effects from the activity and this contributed to the increase in pain tolerance.

Although I do not encourage people to view pain as beneficial as was done in this research, I do use this study to demonstrate the power of our endogenous pain modulating systems and highlight how a change in attitude can shift neurochemistry and, in this case, in a pain inhibitory direction.

1Benedetti F, et al. Pain as a reward: Changing the meaning of pain from negative to positive co-activates opioid and cannabinoid systems. Pain. 2013;154(3):361-7.