A synthesis of meta-analyses of mindfulness-based interventions in pain.

ABSTRACT: Mindfulness interventions have become popular in recent decades, with many trials, systematic reviews, and meta-analyses of the impact of mindfulness-based interventions (MBIs) on pain. Although many meta-analyses provide support for MBIs, the results are more mixed than they at first appear. The aim of this umbrella review was to determine the strength of evidence for MBIs by synthesizing available meta-analyses in pain. We conducted a systematic search in 5 databases and extracted data from published meta-analyses as the unit of analysis. For each outcome, we reported the range of effect sizes observed across studies and identified the largest meta-analysis as the "representative" study. We separately analysed effect sizes for different pain conditions, different types of MBIs, different control groups, and different outcomes. We identified 21 meta-analyses that included 127 unique studies. According to Assessment of Multiple Systematic Review ratings, the meta-analyses ranged from very strong to weak. Overall, there was an impact of MBIs on pain severity, anxiety, and depression but not pain interference or disability. When conditions were considered in isolation, only fibromyalgia and headache benefited significantly from MBIs. Mindfulness-based interventions were more efficacious for pain severity than passive control conditions but not active control conditions. Only pain severity and anxiety were affected by MBIs at follow-up. Overall, our results suggest that individual meta-analyses of MBIs may have overestimated the efficacy of MBIs in a range of conditions. Mindfulness-based interventions likely have a role in pain management but should not be considered a panacea.

Inventory of Personal Factors Influencing Conditioned Pain Modulation in Healthy People: A Systematic Literature Review.

BACKGROUND: Conditioned pain modulation (CPM) is believed to play an important role in the development and exacerbation of chronic pain, because dysfunction of CPM is associated with a shift in balance between pain facilitation and pain inhibition. In many patients with central sensitization, CPM is less efficacious. Besides that, efficacy of CPM is highly variable in healthy people. Consequently, it seems that several individual variables may influence CPM. A systematic review examining personal factors influencing CPM was conducted. METHODS: This systematic review follows the PRISMA guidelines. "Pubmed" and "Web of Science" were searched using different synonyms of CPM. Full-text clinical reports addressing the influence of personal factors on CPM in healthy adults were included. Checklists for RCTs and case-control studies provided by the Dutch Institute for Healthcare Improvement (CBO) and the Dutch Cochrane Centre were utilized to assess methodological quality. Levels of evidence and strength of conclusion were assigned using the CBO guidelines. RESULTS: Forty-six articles were identified that reported the influence of personal factors on CPM. Quality assessment revealed 10 studies with a methodological quality less than 50% wherefore they were excluded (21.8%), resulting in a general total methodological quality score of 72.5%. Overall younger adult age, male gender, ovulatory phase, positive expectations, attention to the conditioning stimulus, and carrier of the 5-HTTLPR long allele result in better CPM. CONCLUSION: It is advised for future studies to take these factors into account. Further research regarding the influence of oral contraceptives, catastrophizing, information about conditioning stimulation, distraction, physical activity, and genetics on CPM magnitude is required.

Pain in patients with chronic fatigue syndrome: time for specific pain treatment?

BACKGROUND: Besides chronic fatigue, patients with chronic fatigue syndrome (CFS) have debilitating widespread pain. Yet pain from CFS is often ignored by clinicians and researchers. OBJECTIVES: To examine whether pain is a unique feature of CFS, or does it share the same underlying mechanisms as other CFS symptoms? Second, it is examined whether effective treatments for pain from CFS are currently available. STUDY DESIGN: Narrative review covering the scientific literature up through December 2011. SETTING: Several universities. RESULTS: From the available literature, it is concluded that musculoskeletal factors are unlikely to account for pain from CFS. Pain seems to be one out of many symptoms related to central sensitization from CFS. This idea is supported by the findings of generalized hyperalgesia (including widespread increased responsiveness to painful stimuli) and dysfunctional endogenous analgesia in response to noxious thermal stimuli. Pain catastrophizing and depression partly account for pain from CFS. Pain increases during exercise is probably due to the lack of endogenous analgesia and activation of several genes in response to exercise in CFS. There is currently no evidence in support for the efficacy of complementary medicine in the treatment of pain from CFS. Intensive education about the biology of pain from CFS (within the framework of central sensitization) has positive short-term effects for patients with CFS, and fatigue-targeting cognitive behavioral therapy appears to be effective for pain from CFS as well. LIMITATIONS: The role of the deficient hypothalamus-pituitary-adrenal axis in relation to pain from CFS, as well as the interactions with immune (dys)functioning require further study. CONCLUSION: Recent research has increased our understanding of pain from CFS, including its treatment. It is advocated to optimize current CFS treatment protocols by targeting the underlying mechanism for those patients having severe pain.

Distraction from pain and executive functioning: an experimental investigation of the role of inhibition, task switching and working memory.

Although many studies have investigated the effectiveness of distraction as a method of pain control, the cognitive processes by which attentional re-direction is achieved, remain unclear. In this study the role of executive functioning abilities (inhibition, task switching and working memory) in the effectiveness of distraction is investigated. We hypothesized that the effectiveness of distraction in terms of pain reduction would be larger in participants with better executive functioning abilities. Ninety-one undergraduate students first performed executive functioning tasks, and subsequently participated in a cold pressor task (CPT). Participants were randomly assigned to (1) a distraction group, in which an attention-demanding tone-detection task was performed during the CPT, or (2) a control group, in which no distraction task was performed. Participants in the distraction group reported significantly less pain during the CPT, but the pain experience was not influenced by executive functioning abilities. However, the performance on the distraction task improved with better inhibition abilities, indicating that inhibition abilities might be important in focussing on a task despite the pain.

The role of motivation in distracting attention away from pain: an experimental study.

Research on the effectiveness of distraction as a method of pain control is inconclusive. One mechanism pertains to the motivational relevance of distraction tasks. In this study the motivation to engage in a distraction task during pain was experimentally manipulated. Undergraduate students (N=73) participated in a cold pressor test (CPT) and were randomly assigned to three groups: a distraction-only group performed a tone-detection task during the CPT, a motivated-distraction group performed the same task and received a monetary reward for good task performance, and a control group did not perform the tone-detection task. Results indicated that engagement in the distraction task was better in the motivated-distraction group in comparison with the distraction-only group. Participants in both distraction groups experienced less pain compared to the control group. There were no overall differences in pain intensity between the two distraction groups. The effect of distraction was influenced by the level of catastrophic thinking about pain. For low catastrophizers, both distraction groups reported less pain as compared to the non-distracted control group. This was not the case for high catastrophizers. For high catastrophizers it mattered whether the distraction task was motivationally relevant: high catastrophizers reported less intense pain in the motivated-distraction group, as compared to the non-distracted control group. We conclude that increasing the motivational relevance of the distraction task may increase the effects of distraction, especially for those who catastrophize about pain.

Differentiating orienting and defensive responses to concealed information: the role of verbalization.

Using physiological measures, concealed information can be validly assessed. Orienting theory has been proposed to account for concealed information testing. As orienting is characterized by heart rate deceleration, one would expect this type of heart rate response to concealed information. However, with some exceptions, an initial heart rate acceleration to concealed information is typically observed. In the present paper, we examine the role of verbalization to explain the mixed pattern of heart rate changes. Using a within-subjects design, 30 participants were asked to either remain silent or to give an overt verbal response ("yes"/"no") to concealed autobiographical and control information. The results indicate that verbalization accounts for the initial heart rate acceleration. In line with the orienting theory, initial heart rate deceleration is observed when participants remained silent.

Hyperventilation in patients with chronic fatigue syndrome: the role of coping strategies.

Hyperventilation has been suggested as a concomitant and possible maintaining factor that may contribute to the symptom pattern of chronic fatigue syndrome (CFS). Because patients accepting the illness and trying to live with it seem to have a better prognosis than patients chronically fighting it, we investigated breathing behavior during different coping response sets towards the illness in patients with CFS (N=30, CDC criteria). Patients imagined a relaxation script (baseline), a script describing a coping response of hostile resistance, and a script depicting acceptance of the illness and its (future) consequences. During each imagery trial, end-tidal PCO2 (Handheld Capnograph, Oridion) was measured. After each trial, patients filled out a symptom checklist. Results showed low resting values of PetCO2 overall, while only imagery of hostile resistance triggered a decrease and deficient recovery of PetCO2. Also, more hyperventilation complaints and complaints of other origin were reported during hostile resistance imagery compared with acceptance and relaxation. In conclusion, hostile resistance seems to trigger both physiological and symptom perception processes contributing to the clinical picture of CFS.

Impaired disengagement from threatening cues of impending pain in a crossmodal cueing paradigm.

This paper reports an experimental investigation of attentional engagement to and disengagement from cues of impending pain. Pain-free volunteers performed a cueing task in which they were instructed to detect somatosensory and tone targets. Target stimuli were preceded by visual cues informing participants of the modality of the impending stimuli. Participants were randomly assigned to a pain group (n = 54) or to a control group (n = 53). Somatosensory targets consisted of painful electrocutaneous stimuli in the pain group and non-painful vibrotactile targets in the control group. Analyses revealed a similar amount of attentional engagement to both cues signalling somatosensory targets, irrespective of their threat value. However, participants had significantly more difficulty in disengaging attention from a threatening cue of impending pain compared to a cue signalling the non-painful vibrotactile target. Our findings provide further evidence that pain cues demand attention, particularly resulting in impaired disengagement.

Disengagement from pain: the role of catastrophic thinking about pain.

This paper reports an experimental investigation of attentional engagement to and disengagement from pain. Thirty-seven pain-free volunteers performed a cueing task in which they were instructed to respond to visual target stimuli, i.e. the words 'pain' and 'tone'. Targets were preceded by pain stimuli or tone stimuli as cues. Participants were characterized as high or low pain catastrophizers, using self-reports. We found that the effect of cueing upon target detection was differential for high and low pain catastrophizers. Analyses revealed a similar amount of attentional engagement to pain in both groups. However, we also found that participants high in pain catastrophizing had difficulty disengaging from pain, whereas participants low in pain catastrophizing showed no retarded disengagement from pain. Our results provide further evidence that catastrophic thinking enhances the attentional demand of pain, particularly resulting in difficulty disengaging from pain. The clinical implications of these findings are discussed.

How can we learn to live with pain? A Q-methodological analysis of the diverse understandings of acceptance of chronic pain.

An analysis is reported of the variety of understandings available in British culture to understand acceptance of chronic pain. Q-factor analysis is used within a critical framework as Q-methodology. Thirty participants completed the procedure. Eight factors or accounts of accepting chronic pain were derived. These are reported as taking control, living day to day, acknowledging limitations, empowerment, accepting loss of self, more to life than pain, don't fight battles that cannot be won, and spiritual strength. Common features of accepting chronic pain are (1) the acknowledgement that a cure for pain is unlikely, (2) a shift of focus away from pain to non-pain aspects of life, and (3) a resistance to any suggestion that pain is a sign of personal weakness. Where accounts of chronic pain differ is in the extent to which acceptance of pain means a change in core aspects of self. Implications of this study for the study of chronic pain are discussed. In particular, how identity is managed in the context of threatening chronic pain is suggested as a fruitful area of future investigation.