New research provides novel insight into how mindfulness alters pain-related activity in the brain, in findings that point to more targeted pain management.
In a randomized trial, more than 100 healthy individuals were assigned to an 8-week mindfulness-based stress reduction (MBSR) program, a health improvement program (HEP) of the same length, or a waiting list.
Scanning participants' brains during a heat-based stimulus pain task showed those who completed the MBSR had a reduction in a brain signature linked to the sensory intensity of pain.
"Our finding supports the idea that for new practitioners, mindfulness training directly affects how sensory signals from the body are converted into a brain response," lead investigator Joseph Wielgosz, PhD, of the Center for Healthy Minds, University of Wisconsin-Madison, said in a release.
Further analysis in long-term meditation practitioners showed the total time spent on intensive retreats was associated with neural changes associated with the perceived stress of pain.
"Just like an experienced athlete plays a sport differently than a first-timer, experienced mindfulness practitioners seem to use their mental 'muscles' differently in response to pain than first-time meditators," Wielgosz noted.
The findings were published online July 28 in the American Journal of Psychiatry.
A Complex Condition
Wielgosz told Medscape Medical News that pain is "complex," with multiple stages and several phases between the time signals are sent from pain receptors and the experience of pain.
"The way that mindfulness affects pain processing has more to do with the way the brain interprets pain signals."
The investigators note that understanding the neurocognitive mechanisms underlying the efficacy of nonpharmacologic pain interventions is a "high-priority objective for improving pain treatment."
Evidence from brief laboratory interventions and cross-sectional studies suggests that mindfulness training is associated with alterations in both sensory processing and cognitive-emotional regulatory networks, the investigators note.
"However, no such study has yet been conducted on a standardized, full- length, and widely used clinical intervention, such as MBSR," they add.
Thermal Pain Task
The randomized, active-control trial included 115 healthy, meditation-naive individuals (61.7% women; average age, 48.3 years). Just over half (58%) had a graduate degree and their mean score on the Hollingshead index was 58.3, indicting a higher socioeconomic status.
All were randomly assigned to an 8-week MBSR course, an 8-week HEP course as an active control group, or a waiting-list control group with no intervention.
The MBSR involved instruction and practice in continuous focused attention on the breath, bodily sensations, and mental content while in seated postures, walking, and doing yoga.
The HEP matched the MBSR in terms of its length, structure, and nonspecific therapeutic elements, which included a supportive group atmosphere, expert instruction, and positive expectancy for benefit.
To examine the interventions' effect on the pain experience, participants underwent a pain task in which they had 20 thermal stimuli applied to the inside of the left wrist for 12 seconds, including 8 seconds at peak temperature.
The stimuli were separated by a distractor task and intervals for cued anticipation, recovery, and subjective ratings of intensity and unpleasantness on a scale of 0-20.
During the task, participants underwent MRI to assess the neurologic pain signature (NPS) and the stimulus intensity independent pain signature-1 (SIIPS-1) within the brain.
The NPS is activated by various types of pain stimuli, while responding minimally or not at all to "emotionally evocative stimuli" relating to pain or to placebo treatment, the researchers note.
In contrast, the SIIPS-1 is activated in response to aspects of pain unrelated to the stimulus itself. It incorporates a "broader range of cognitive and emotional modulatory circuits," including those related to expectancy and cognitive processes to modulate the pain experience.
Results showed that in all groups, age was significantly negatively associated with both NPS (P = .001) and SIIPS-1 response (P < .001), although not subjective pain reports, and was subsequently included in all analyses of neural signatures.
Persons in the MBSR group had a significant decrease in the NPS compared with those in the HEP group (P = .05), and from pre- to postintervention assessments (P = .023).
Those in the MBSR group also had "marginal" decreases in the NPS vs the waiting list group (P = .096), and in the SIIPS-1 relative to both the HEP (P = .089) and waiting-list groups (P = .087).
In subjective pain ratings, the MBSR group showed a marginal decrease compared with the waiting-list group (P = .078), and from the pre-to postintervention assessments (P = .028).
The HEP group also had marginal decreases in pain unpleasantness vs the waiting-list group (P = .043), and from the pre- to postintervention assessments for pain intensity (P = .046) and unpleasantness (P = .007).
The researchers also assessed 30 long-term meditators who had undertaken at least 3 years of formal experience with meditation, including participating in multiple intensive retreats and ongoing daily practice, and compared them with meditation-naive individuals.
Long-term meditators reported significantly less pain intensity and unpleasantness than those who had not undergone the training (P < .001).
In addition, a higher number of practice hours during a retreat was linked to a greater reduction in pain ratings. This association remained even after adjustment for gender and respiration rate.
However, the number of daily practice hours was not significantly associated with pain ratings among long-term meditators.
Although there were no average differences in neural signature responses between long-term meditators and individuals who were naive to the technique, there was an inverse relationship between hours on retreat and SIIPS-1 response (P = .027).
'We're Seeing the Biology Change'
Commenting for Medscape Medical News, Fadel Zeidan, PhD, associate professor of anesthesiology, University of California, San Diego, said that in attenuating the experience of pain, mindfulness engages "very novel" mechanisms.
However, the "most remarkable thing about this study" is that the pain effect occurred when the participants were not meditating, "which gives rise to the notion that mental training is just like physical training," said Zeidan, who was not involved with the research.
He noted that the notion was not appreciated previously, "because we weren't able to see the changes," as they were based on self-report alone.
However, combining those reports with brain imaging and other objective methods means that "we're actually seeing the biology change," Zeidan said.
He added that mindfulness is different from other techniques for modulating the pain experience, because it is self-facilitated.
"People can learn this technique, ideally, for free online. They can learn the recipe, and it's one of the only techniques out there that can be used immediately to assuage one's own pain," he said.
"There's nothing else out there on this planet that could immediately reduce one's own pain. You have to wait 45 minutes for Tylenol, distraction can only work for so long, and you can't really placebo yourself," Zeidan added.
The study was funded by a National Center for Complementary and Alternative Medicine grant, NIMH grants, a Fetzer Institute grant, and a John Templeton Foundation grant, as well as a core grant to the Waisman Center from the National Institute of Child Health and Human Development to Albee Messing. Wielgosz and Zeidan have reported no relevant financial relationships. Disclosures for the co-investigators are listed in the original article.
Am J Psychiatry. Published online July 28, 2022. Abstract
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Cite this: Mindfulness 'Changes the Biology' of Pain - Medscape - Aug 15, 2022.