The journal of pain : official journal of the American Pain Society
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Persistent pain is a major public health issue-estimated to affect a quarter of the world's population. Public understanding of persistent pain is based on outdated biomedical models, laden with misconceptions that are contrary to best evidence. This understanding is a barrier to effective pain management. ⋯ Furthermore, it is crucial that campaigns are undertaken through a health equity lens, incorporating underrepresented communities to ensure that any intervention does not widen existing health inequalities associated with persistent pain. PERSPECTIVE: Public misconceptions about pain are a significant public health challenge and a viable intervention target to reduce the personal, social, and economic burden of persistent pain. Adaptation of Pain Science Education, which improves misconceptions in a clinical setting, into the public health setting seems a promising approach to explore.
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Randomized Controlled Trial
Exploring HD-tDCS effect on μ-opioid receptor and pain sensitivity in temporomandibular disorder: A pilot randomized clinical trial study.
This study explored the association between experimentally-induced pain sensitivity and µ-opioid receptor (μOR) availability in patients with temporomandibular disorder (TMD) and further investigated any changes in the pain and μOR availability following high-definition transcranial direct current stimulation (HD-tDCS) over the primary motor cortex (M1) with pilot randomized clinical trials. Seven patients with TMD completed either active (n = 3) or sham treatment (n = 4) for 10 daily sessions and underwent positron emission tomography (PET) scans with [11C]carfentanil, a selective μOR agonist, a week before and after treatment. PET imaging consisted of an early resting and late phase with the sustained masseteric pain challenge by computer-controlled injection of 5% hypertonic saline. ⋯ TRIAL REGISTRATION: ClinicalTrial.gov (NCT03724032) PERSPECTIVE: This study links pain sensitivity and µ-opioid receptors in patients with TMD. HD-tDCS over M1 improved µOR availability, which was associated with reduced pain sensitivity. Implications for TMD pain management are promising, but larger clinical trials are essential for validation.
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Randomized Controlled Trial
Understanding the role of expectancy, anticipatory anxiety and attention bias in nocebo hyperalgesia: A gaze-contingent attention bias modification study.
Nocebo effects in pain (nocebo hyperalgesia) have been thoroughly researched, and negative expectancies have been proposed as a key factor in causing nocebo hyperalgesia. However, little is known about the psychological mechanisms by which expectations exacerbate the perception of pain. A potential mechanism that has been proposed within wider pain research is pain-related attention. ⋯ The study shows that expectancy can trigger anticipatory anxiety that exacerbates nocebo hyperalgesia. Further, successful AB training towards pain heightens nocebo hyperalgesia. These findings identify candidate psychological factors to target in minimizing nocebo hyperalgesia.
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Caffeine consumption inhibits acupuncture analgesic effects by blocking adenosine signaling. However, existing evidence remains controversial. Hence, this study aimed to examine the adenosine A1 receptor (A1R) role in moderate-dose caffeine-induced abolishing effect on acupuncture analgesia using A1R knockout mice (A1R-/-). ⋯ Overall, our study suggested that caffeine consumption should be avoided during acupuncture treatment. PERSPECTIVE: Moderate-dose caffeine injection attenuated EA-induced antinociceptive effect in formalin- and CFA-induced inflammatory pain mice models by blocking A1R. This highlights the importance of monitoring caffeine intake during acupuncture treatment.
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Conditioning and expectation are known to be the main mechanisms of placebo analgesia. They may operate together, so that expectations may be enhanced by a conditioning procedure. Although most of the studies have tried to potentiate expectations through conditioning in order to generate good placebo responders, a few studies have tried to mismatch conditioning and expectations in order to investigate the subsequent administration of a placebo. ⋯ They also stress the importance of expectations in the therapeutic outcome, with important implications for clinical trials. PERSPECTIVE: By using mismatch conditioning, in which study participants did not get what they expected, we reduced expectations of analgesia, and this reduction abolished placebo analgesia. This effect extended to other parts of the body and other types of pain, which indicates that placebo nonresponders can be created in the laboratory.