Mindfulness as a technique
The practice of Mindfulness Meditation stems from easter Zen Buddhist, Vipassana and Yoga practices (Kabat-Zinn, 1985) and has been brought into clinical practice in the nineteen-seventies.
Hilton et al. (Hilton L, 2017) in their systematic review of mindfulness meditation intervention for chronic pain describe Mindfulness Meditation as facilitating “an attentional stance of detached observation” and being characterized by “paying attention to the present moment with openness, curiosity, and acceptance”.
The refractory nature of chronic pain and the natural desire of patients to exert some control over their pain experience, have carried the practice of Mindfulness into the lime light of clinical pain research and treatment.
Can mindfulness be an inherent trait?
Mindfulness is a technique which can be trained; however, some individuals have inherent mindfulness traits, causing their experience of pain to be in the present moment and with little emotional attributions.
Harrison et al. (Harrison, 2019) explored trait mindfulness in mindfulness meditation-naïve subjects by thermal threshold testing and functional Magnetic Resonance Imaging.
In this study, 45 healthy participants were recruited and assessed for their level of pain reactivity, pain-related psychological factors measured with the Pain Catastrophizing Scale (PCS) (Sullivan, 1995), and trait mindfulness assessed using the Five Facet Mindfulness Questionnaire (FFMQ) (Baer, 2006).
Participants underwent heat pain threshold testing using Medoc’s Pathway, calculated through a mean of both the Limits and Levels heat pain threshold results.
Resting-state functional images were captured of all participants. The precuneus cortex was selected as a default mode network node region of interest for a seed-based whole brain functional connectivity analysis.
The authors found that higher trait mindfulness was significantly correlated to higher pain thresholds, i.e. pain is first reported at a higher temperature, and that higher mindfulness was inversely correlated with the measure of pain catastrophizing. However, pain catastrophizing was not directly correlated to pain thresholds.
Analysis of the imaging data found that mindfulness was associated with the precuneus default mode network connectivity to the somatosensory cortices, but also with a weaker connectivity to the medial prefrontal cortex.
Trait mindfulness seems to be involved in both emotional and somatosensory processing and leaves its footstep in functional connectivity, as expressed by default mode network connection differences between “mindfulers” and “non-mindfulers”.
Mindfulness and Chronic pain
But how does mindfulness affect chronic pain? Wells et al. (Wells, 2021) sought to elucidate this effect on migraineurs who were treated with either Mindfulness Meditation or Headache Education for two hours each week for the duration of eight weeks.
Their study included 89 patients with varying frequency of monthly attacks. Measures that were included in this research endeavor were: monthly migraine day frequency, measures regarding headache symptoms and medication use. Several questionnaires of wellbeing, depression, and quality of life were taken.
In addition, on headache-free visit days, patients were administered series of noxious thermal stimuli, between 43 and 49 °C using the TSA-II 16*16 mm thermode, after which they rated their pain using a visual analogue scale.
Remarkably, Mindfulness Meditation did not significantly differ in number of headache days from Headache Education intervention. In contrast, other measures did seem to note down the effect of this intervention, specifically questionnaires in assessing disability, pain catastrophizing, depression, quality of life, and self-efficacy. Analysis of the quantitative sensory testing (QST) data showed that the Mindfulness intervention caused a decrease in both pain unpleasantness, as well as pain intensity, while the Headache Education group did not find this relief.
Mindfulness and endogenous pain modulation
Tsur et al. (Tsur, 2021) set out to explore the effect of mindfulness on central pain processing. The authors recruited 60 healthy volunteers who were randomized into pain-specific mindfulness, nonspecific mindfulness, and a control group.
The pain-specific mindfulness group were trained on mindfulness to pain by two series of 2.5 minutes of pain stimuli of varying intensities of both the hot pain and the cold pain range. During the first series they were requested to rate their pain of VAS scale (0 - no pain, to 10 - the most intense pain sensation imaginable), while during the second series they were only requested to be mindful to their pain sensations, without pain reporting.
The nonspecific mindfulness group were given a task of finding differences between two visual cues, two almost identical images for 5 minutes.
The control group were tasked with sketching on a blank sheet of paper for 5 minutes.
A conditioned pain modulation (CPM) paradigm, using contact heat at the intensity of VAS 5-6 (with Medoc’s TSA) as a test stimulus and a hot water bath (46 °C) as a conditioning stimulus, was performed twice at short intervals. The first CPM paradigm with a robust conditioning stimulus, while the second paradigm was performed with a less intense conditioning stimulus. The short interval between the CPM paradigms and the milder conditioning stimulus were implemented in order to mimic a “deficient” CPM in the second paradigm. The three groups; mindfulness training, sham-mindfulness training and controls were compared in their decline in CPM efficacy. CPM efficacy or magnitude is the measure of pain inhibition by the CPM protocol. The more “negative” this number, the more effective the descending pain modulation. Interestingly, only in the control group did CPM magnitude decline significantly, while in the both mindfulness groups, the CPM effect was upheld.
Does Mindfulness meditation inhibit pain through descending opioid pathways?
A different group (Zeidan, 2016) investigated the connection between mindfulness meditation and endogenous opioid-based pain inhibition. In their study, 95 healthy volunteers were recruited. The participants were randomized into 4 groups: mindfulness + naloxone, mindfulness + saline, control + naloxone, control + saline. Naloxone is an opioid receptor antagonist which is known to reverse the effects of conditioned pain modulation.
For the mindfulness group, mindfulness training consisted of 4 training days during which the participants received training and instruction of mindfulness meditation for 20 minutes.
The control group received a natural history book listening regime of 20 minutes a day for 4 days.
All participants were subjected to 10 alternating plateaus of 35 and 49 °C contact heat by the TSA-II with 12 sec. duration. Participants were requested to rate their pain intensity and pain unpleasantness on the VAS between 0 – “no pain sensation/not at all unpleasant” and 10 – “most intense pain sensation imaginable/most unpleasant sensation imaginable”.
Participants were subjected to two heat pain series prior to administration of naloxone/saline, where they rated their pain on VAS for intensity and unpleasantness. After administration, subjects received another two series of heat pain stimuli during which the mindfulness group was instructed to meditate and the control group was instructed to rest.
Remarkably, mindfulness + saline was effective in reducing pain intensity and was statistically significant in comparison with control + saline where, au contraire, pain intensity increased.
Under both conditions, mindfulness + saline and mindfulness + naloxone, there was pain reduction and no statistically significant difference was found in this pain reduction between these two conditions. Moreover, there was a statistically significant reduction under the mindfulness + naloxone condition in comparison to the control with saline and the control with naloxone condition.
Based on these findings, it may be concluded that the pain reduction experienced under the influence of mindfulness is not associated with the endogenous opioid system as is classically tested using conditioned pain modulation. It needs to be stated, however, that the paradigm which was used in this trial did not contain a conditioning stimulus, and as such, may not activate the descending inhibition through diffuse noxious inhibitory controls.
In summary, even though the mode of action of mindfulness pain relief has not fully been elucidated, it seems that those for whom mindfulness is not an inherent trait, it is certainly worthwhile trying.
References
Baer, R. A. (2006). Using self-report assessment methods to explore facets of mindfulness. Assessment, 27-45.
Harrison, R. Z. (2019). Trait mindfulness is associated with lower pain reactivity and connectivity of the default mode network. The Journal of Pain, 645-654.
Hilton L, H. S. (2017). Mindfulness meditation for chronic pain: systematic review and meta-analysis. Annals of Behavioral Medicine, 199-213.
Kabat-Zinn, J. L. (1985). The clinical use of mindfulness meditation for the self-regulation of chronic pain. Journal of behavioral medicine, 163-190.
Sullivan, M. B. (1995). The Pain Catastrophizing Scale: Development and Validation. Psychol Assess, 524-532.
Tsur, N. D. (2021). The effect of mindful attention training for pain modulation capacity: Exploring the mindfulness–pain link. Journal of clinical psychology, 896-909.
Wells, R. E. (2021). Effectiveness of mindfulness meditation vs headache education for adults with migraine: a randomized clinical trial. JAMA Internal Medicine, 317-328.
Zeidan, F. A.-N. (2016). Mindfulness-Meditation-Based Pain Relief Is Not Mediated by Endogenous Opioids. The Journal of Neuroscience, 3391–3397.