Government officials, physicians, and the public are increasingly aware of a need to move away from using opiate drugs to treat chronic pain. More and more, doctors are searching for ways to help patients manage pain with non-pharmacological interventions. In line with this trend, new findings now support the use of mindfulness to treat chronic low back pain.
In a clinical trial published March 22 in the Journal of the American Medical Association (JAMA), subjects who underwent mindfulness training for eight weeks were more likely to report improvements in pain, lasting up to a year, compared to people who received whatever other care they chose. The study was led by Daniel Cherkin, Group Health Research Institute, Seattle, US, and Judith Turner, University of Washington, also in Seattle.
A second study, published March 16 in the Journal of Neuroscience and led by Fadel Zeidan, Wake Forest School of Medicine, Winston-Salem, North Carolina, US, and Robert Coghill, now at Cincinnati Children’s Hospital, Ohio, US, hints at how mindfulness might reduce pain. The researchers showed in healthy subjects that meditation reduced acute pain independent of endogenous opioids, which account for the vast majority of other brain-based manipulations—such as the placebo effect or conditioned pain modulation.
A non-pharmacological intervention for back pain
Despite intense investigation of mindfulness in recent years, few large randomized clinical trials of mindfulness for pain have been conducted previously. A trial published in JAMA Internal Medicine in March found that mindfulness was effective at improving short-term function, and in providing some long-term pain relief, in chronic low back pain patients over age 65 compared to controls who received a healthy aging education program (Morone et al., 2016).
The current trial included adults aged 20 to 70 (an average age of 50) who had experienced chronic low back pain with no discernible underlying cause for at least three months before the study began. The investigators followed nearly 300 subjects—who were mostly women and white—for a year. Subjects were randomized to receive usual care alone or the addition of either a standard eight-week program of Mindfulness-Based Stress Reduction (MBSR) or eight weeks of cognitive-behavioral therapy (CBT). With MBSR, practitioners bring attention to the present moment without judgment, whereas CBT consists of talk therapy with a psychologist aimed at reframing one’s situation. “The comparison included one type of mind-based approach—CBT—that has already been studied and found effective,” Cherkin said (Ehde et al., 2014).
Six months after the training, compared to the group receiving usual care, more patients receiving CBT or MBSR saw at least a 30 percent reduction—deemed clinically relevant—in self-ratings of “pain bothersomeness”; only about 26 percent of patients receiving usual care compared to nearly 45 percent with MBSR or CBT saw the improvement. More patients receiving MBSR or CBT also saw clinically relevant improvements in functional limitation measured by the Roland Disability Questionnaire (RDQ)—about 60 percent of those with MBSR or CBT compared to only 44 percent of control subjects. Subjects randomized to MBSR were more likely than those receiving usual care to show improvements on the RDQ (relative risk 1.37) and in pain bothersomeness (relative risk 1.64). Strikingly, the improvements were still evident a year after the interventions. These therapies, Cherkin said, can “change how we think about and react to pain—they give you the skills to do that.”
David Seminowicz, who studies pain and mindfulness at the University of Maryland, Baltimore, US, who was not involved in either new study, said the trial provides “the best evidence currently out there for MBSR as an intervention for chronic pain. This is a well-done study by a group that does careful work. And the results are clear: MBSR and CBT were superior to usual care” for managing chronic low back pain, he said.
Only about half the subjects randomized to either the MBSR or CBT groups attended at least six of the eight sessions. The study used an “intent to treat” design, one commonly used in clinical trials, whereby subjects are included in the analysis regardless of how much of a drug or intervention they undertake. “We could speculate that, had we had better participation, we might have seen even better improvements,” Cherkin said. Seminowicz said that in using intent to treat, “the authors did exactly what you’re supposed to do for such a trial,” but that “it would be really interesting to see if the people who complied with the intervention did a lot better” than those who did not attend many sessions.
Cherkin said that although the improvements with MBSR were not large, they are clinically important. “Most people didn’t get enormously better with MBSR, and some people would have gotten better anyway. But with a tough problem like back pain that lasts for years, for which people have tried a lot of things that haven’t worked,” MBSR provides a new option to make pain more manageable, he said.
The mindfulness mechanism
In the second study, Zeidan and colleagues built on previous work investigating how meditation might relieve acute pain in healthy people (Zeidan et al., 2015; Zeidan et al., 2011). Some of the 78 subjects—mostly white men and women with an average age of 27—underwent just four days of training in mindfulness meditation for 20 minutes per day, during which they were instructed to continually focus on the physical sensation of breath while acknowledging intruding thoughts without judgment. Control subjects listened to a history book on tape for the same time period.
During the experiment, subjects trained in mindfulness were instructed to meditate while researchers applied a hot probe to the back of their right calf, whereas control subjects were instructed to close their eyes and relax. The meditators rated the pain intensity and unpleasantness significantly lower during meditation than they had during a baseline measurement before training—down 21 percent and 36 percent, respectively. Control subjects, in contrast, reported increased pain intensity (up 21 percent) and unpleasantness (up 18 percent) compared to their baseline.
Next, the researchers wanted to test whether endogenous opioids were responsible for the pain reduction seen in meditators. In previous work, Zeidan said, “We showed that meditation recruits brain areas that contain high levels of opioid receptors,” perhaps indicating a role for opioids, and yet “meditation also deactivated the PAG [periaqueductal gray], a region critical in facilitating opioidergic descending inhibition of pain. So on one hand, it looked like opioids were responsible, but on the other hand, it didn’t.”
In the current study, half the subjects in each group received an injection of saline, while the other half received a large dose of naloxone, an opioid receptor antagonist, to block any endogenous opioid actions. When the heat stimuli were applied, pain ratings were not significantly changed compared to subjects receiving saline; that is, meditators experienced reduced pain intensity (24 percent lower) and unpleasantness (33 percent lower) compared to their baseline regardless of whether they received saline or naloxone. Control subjects’ pain ratings were also indistinguishable between those receiving saline or naloxone. Importantly, the result demonstrated that endogenous opioids were not required for the mindfulness-associated analgesia.
“The results they present are convincing in that naloxone alone was not sufficient to block acute effects of meditation-based analgesia,” Seminowicz said. But the finding cannot entirely rule out a role for endogenous opioids. “It’s one thing to say opioids are not required for this acute effect to occur, and another thing to say that they’re not part of what contributes to the overall analgesia provided by mindfulness meditation,” Seminowicz said. Indeed, the authors suggest that other descending modulatory systems could be involved—perhaps serotoninergic, for example—which might or might not interact with opioidergic systems.
“In the area of pain research that’s focused on the brain, when we see pain analgesia,” Seminowicz said, “we overwhelmingly look at descending modulation—there must be something shutting down pain systems at the brainstem level. But the other possibility, which is harder to investigate, is that higher circuits involved in actually creating the experience of pain could be altered in some way.” Perhaps with mindfulness and other cognitive manipulations, “the pain becomes perhaps not as meaningful, not as intense,” Seminowicz said.
Based on his previous imaging studies of mindfulness and acute pain, Zeidan hypothesizes that mindfulness meditation dampens signals from the thalamus to the cortex, perhaps reshaping the experience of pain. “That is a reasonable and testable hypothesis, so I hope to see them follow up on that,” Seminowicz said.
Different studies, different aims
The two new studies differ significantly while both addressing important questions about mindfulness: Is it effective for pain, and how does it produce analgesia? The clinical trial in JAMA showed that mindfulness is effective for chronic low back pain. As for how it worked in that chronic pain population, researchers can only speculate at this point. Zeidan’s study of acute pain in healthy people showed that mindfulness produced analgesia without the need for endogenous opioids, but what that says about how the technique works in chronic pain patients remains unclear. “There is quite a leap from the brains of healthy subjects to those with chronic pain, where we know that changes are occurring on multiple levels. We don’t know how that affects things like descending modulation,” Seminowicz said.
Zeidan agreed, saying that he would love to one day carry out imaging and other studies of mindfulness in chronic pain patients, but that this study is a start toward understanding how meditation alters pain signals in the healthy brain. “First, we want to understand the mechanisms so that we can tailor the treatment to patients in the future,” Zeidan said.
One barrier to using mindfulness as a treatment for chronic pain is that it requires active effort on the part of patients. Cherkin acknowledges that mindfulness will not work for everyone, and that a prerequisite for participation in the clinical trial was a willingness to undergo the training, so the treatment is “restricted to people open to that idea,” he said. While it may be easier to take a pill or rely on a doctor to solve the problem, chronic pain does not seem to be solved by such simple solutions, he added.
Another difference between the studies was the time course of the intervention: eight weeks in the clinical trial versus four days of training in Zeidan’s study. With the four-day training regimen used in his study, Zeidan hopes to move closer to a “pill form” of meditation that patients might find more palatable than extended training. “We are accumulating evidence that meditation’s effects on pain can be realized with very short training,” he said. A fast-acting, non-pharmacological, inexpensive treatment for chronic pain? That might be a pill everyone can swallow.
Stephani Sutherland, PhD, is a neuroscientist, yogi, and freelance writer in Southern California.
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