Review of research into meditation for pain management
Some of the first quantitative papers published on the medical benefits of mindfulness concerned a cohort of 51 chronic pain patients who enrolled in a ten- week mindfulness meditation training program (Kabat-Zinn 1982). The dominant pain categories were lower back, neck and shoulder, and headache pain. These were patients who had not improved with traditional medical care. At ten weeks, 65% of the patients showed a reduction of greater than or equal to 33% in the mean total Pain Rating Index, and 50% showed a reduction of greater than or equal to 50%. Similar decreases were recorded on other pain indices and in the number of medical symptoms reported. Large and significant reductions in mood disturbance and psychiatric symptomatology accompanied these changes and were relatively stable on follow-up. Two years later a similar study was published (Kabat-Zinn et al. 1985), which showed statistically significant reductions in measures of present-moment pain, negative body image, inhibition of activity by pain, symptoms, mood disturbance, and psychological symptomatology, including anxiety and depression. Pain-related drug utilization decreased and activity levels and feelings of self-esteem increased. At follow-up, the improvements observed during the meditation training were maintained up to 15 months post-meditation training for all measures except present-moment pain. The majority of subjects reported continued high compliance with the meditation practice as part of their daily lives. However, these were not randomized clinical trials, but rather observational studies, and we therefore do not know how much of the improvement was part of the natural course of illness and wellness.
These early studies looking into the role meditation can play in pain management provided tantalizing evidence that benefit could be gained. Since then there has been an explosion of interest in mindfulness research generally, including studies related to chronic pain. However, there is a need for more high-quality research in this emerging field.
In 2010, Arthritis Research UK conducted a literature review looking specifically at meditation for chronic pain. The report reviewed 91 pieces of evidence, including evidence summaries, systematic reviews, and primary research. The paper concluded that: “this report identifies the lack of high quality clinical trial evidence . . . in establishing the effectiveness and underlying psychological processes of mindfulness-based interventions in the context of chronic musculoskeletal pain” (Arthritis Research UK 2010). The report also identified a lack of consensus regarding definitions, components, and processes of mindfulness meditation and the need for future research to include systematic reviews of meditation for chronic pain.
In 2013 a major systematic review and meta-analysis was conducted into meditation programs for psychological stress and well-being, which included reviewing the effectiveness of meditation for pain (Goyal et al. 2014). Meditation techniques were defined as those emphasizing mindfulness, concentration, and automatic self-transcendence. After reviewing 18,753 citations, the researchers found 47 trials to match their research criteria of randomized clinical trials with active controls for placebo effects through November 2012 from MEDLINE, PsycINFO, EMBASE, PsycArticles, Scopus, CINAHL, AMED, the Cochrane Library, and hand searches. The review reported that “The strength of evidence is moderate that mindfulness meditation programs have a small improvement in pain severity among a variety of populations when compared with a nonspecific active control” (Goyal et al. 2014, p. 119). Other findings in this review included moderate evidence of improved anxiety (effect size, 0.38 [95% CI, 0.12-0.64] at 8 weeks and 0.22 [0.02-0.43] at 3-6 months) and depression (0.30 [0.00-0.59] at 8 weeks and 0.23 [0.05-0.42] at 3-6 months).
As research into meditation for chronic pain develops, researchers are attempting to tease apart the many variables and gain a clearer understanding of how meditation can provide relief to pain sufferers. This includes gaining a deeper understanding of the role that different meditation practices have to play. In general there are two main types of meditation, drawn from Buddhism, that are utilized within meditation programs for pain. These are described as:
- 1 Attention control (Sedlmeier et al. 2012)—In the scientific literature this is most commonly described as focused awareness (FA) (also known as shama- tha in the Buddhist tradition, concentration, and attentional balance (Wallace and Shapiro 2006)). These skills have been identified as basic attentional processes and, along with training the stability and flexibility of one’s attention, the FA practitioner likely engages in cognitive reappraisal by repeatedly reinterpreting distracting events as fleeting or momentary, and doing so with acceptance (Zeidan et al. 2012).
- 2 A shift in perspective—Applied when meditation is used to help people shift the perspective from which they view their subjective experience. This is described as open monitoring (OM) (also referred to as vipashyana in the
Buddhist tradition, or decentering (Safran and Segal 1990), cognitive diffusion (Hayes et al. 1999), deautomization (Deikman 1966), and cognitive balance (Wallace and Shapiro 2006)). Some people also use the word mindfulness itself as a term to specifically describe OM approaches to awareness training. As Sedlmeier and colleagues point out in Chapter 13 of this volume, there is a need to establish consistent nomenclature across the field in order to reduce confusion. While practicing OM, the practitioner experiences the current sensory or cognitive “event” without evaluation, interpretation, or preference. This is sometimes referred to as “non-judgmental” awareness. Zen meditation is considered to be one form of OM practice (Austin 1999, p. 844).
Zeidan et al. (2012) examined a range of studies into mindfulness for pain and concluded that the OM style of meditation is more effective at reducing pain after extensive meditation training, as compared to FA. Support for this can be found in Grant and Rainville (2009), which reports that the analgesic effect in advanced meditators, performing an OM-style of attention, did not arise until around 2000 hours of practice. On the other hand, approaches combining elements of both FA and OM are effective at reducing behavioral and neural mechanisms of pain after brief mental training (Zeidan et al. 2010, 2011). These findings suggest that cognitive practices employing attentional stability (focused attention) in conjunction with non-evaluative awareness of sensory events (open monitoring) can reduce pain, even after brief mental training.
In addition to examining the different meditation types that lead to pain reduction, researchers are increasingly using neuroimaging in order to attempt to understand the different neural mechanisms involved. These studies complement the traditional use of self-report questionnaires that the early mindfulness studies relied on. Although the field is very much in its infancy and many questions remain unanswered, some studies assessing the anticipation and experience of acute experimental pain converge to show reduced pain anticipation in meditators associated with increased activation of brain regions implicated in cognitive/emotional control (rostral anterior cingulate cortex (rACC) and ventromedial-prefrontal cortex (vmPFC) (Brown and Jones 2010; Gard et al. 2011)). Brown and Jones (2010) postulated that cultivating an attitude of acceptance toward impending stimuli produces this increased cognitive and emotional control through increased cognitive flexibility. The anticipation or expectation reductions were postulated to be some of the active mechanisms of meditation-related pain relief (Gard et al. 2011).
Gard et al. (2011) also reported that pain can be modulated by mindfulness. A group of mindfulness practitioners and control participants underwent an
MRI scan during which they received unpleasant electrical stimuli during a mindfulness and a control condition. The researchers found that mindfulness practitioners, but not controls, were able to reduce pain unpleasantness by 22% and anticipatory anxiety by 29% during a mindful state. In the brain, this reduction was associated with decreased activation in the lateral prefrontal cortex and increased activation in the right posterior insula during stimulation and increased rACC activation during the anticipation of pain. The rACC is associated with the cognitive modulation of pain, cognitive control, and the regulation of emotions (Ochsner and Gross 2005; Vogt 2005).
Brown and Jones (2013) conducted EEG studies, along with self-report questionnaires, in participants on the Breathworks Mindfulness-Based Pain Management (MBPM) Program, again looking at the effect of mindfulness on pain anticipation using experimentally induced pain stimuli. Twenty-eight patients with chronic pain were assessed and randomized into an intervention group (who attended an eight-week MBPM) or a control group (treatment-as-usual), before being reassessed after eight weeks. Outcome measures included clinical pain, perceived control over pain, mental and physical health, and mindfulness. Neural activity was measured during the anticipation and experience of acute experimental pain, using electroencephalography with source reconstruction. Improvements were found in the MBPM group relative to the control group in mental health, which related to greater perceived control of pain, but not to reductions in clinical or experimental pain ratings. Anticipatory and pain- evoked event-related potentials to acute experimental pain were decreased, but sources of these event-related potentials were estimated to be in regions that modulate emotional responses rather than pain intensity. This study raises interesting questions about the role that emotions can play in the suffering associated with pain, given the participants experienced improved mental health and greater perceived control over pain, even though the actual pain intensity did not reduce to a significant degree. This study is also interesting in that the individuals participating in the study were those who lived with chronic pain, rather than healthy volunteers. The researchers concluded:
The study supports the hypothesis that mindfulness training provides a cognitive strategy for improving pain management, which has positive consequences for mental health. Our results show that this is related to maintaining activity in central executive regions responsible for emotional regulation (DLPFC) during anticipation of pain, whereas reductions in processing during pain experience were modest and restricted to regions that are known to mediate emotional responses to pain including the amygdala and anterior insula (Brown and Jones 2013, p. 243).
Although research into mindfulness for chronic pain is commanding increasing interest, Zeidan et al.’s (2012) review looking at unique brain mechanisms observes that some of the studies appear to contradict each other, showing the need to emphasize the importance of acknowledging differences in dependent measures (fMRI vs. EEG), meditation traditions, meditator experience level, and experimental directives. Clearly, more work is necessary to understand these discrepancies (Zeidan et al. 2012, p. 168). Overall, Zeidan et al. (2012, p. 170) concluded:
In this review we have surveyed the rapidly emerging field of meditation-related pain reduction. The data indicate that, like other cognitive factors that modulate pain, prefrontal and cingulate cortices are intimately involved in the modulation of pain by mindfulness meditation. Mindfulness meditation, like other cognitive manipulations, alters the contextual evaluation of pain but is likely to do so dynamically over time and experience, such that beginners reappraise events and the most advanced practitioners may refrain from elaboration/appraisal entirely. Admittedly, many of these interpretations are based on reverse inference and assumptions derived from traditional claims and require more scrutiny in future research. Nonetheless, mindfulness-related pain reduction promises to be an important tool for understanding how our awareness of sensory events occurs as well as a potentially important adjunct to current treatment options for acute and chronic pain.
For more on the evidence base of MBIs for chronic pain, see Carlson in Chapter 9 of this volume.