Pain
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Forty-five women with fibromyalgia (FM) engaged in a 30-day electronic diary assessment, recording daily ratings of pain and 2 forms of maladaptive coping: pain catastrophizing and pain attention. Participants were genotyped for the val(158)met single nucleotide polymorphism (rs4680) in the catechol-O-methyltransferase (COMT) gene. COMT genotype moderated the daily relations of both maladaptive coping processes and pain. ⋯ Further, the findings advance our understanding of the role of COMT in FM, suggesting that genetic variation in the val(158)met polymorphism may affect FM pain through pathways of pain-related cognition. This study examined 2 forms of maladaptive coping: pain catastrophizing and pain attention. The findings provide multimeasure and multimethod support for genetic moderation of a maladaptive coping and pain process and suggest that genetic variation in the val(158)met polymorphism may affect fibromyalgia pain through pathways of pain-related cognition.
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Attention is acknowledged as an important factor in the modulation of pain. A recent model proposed that an effective control of pain by attention should not only involve the disengagement of selective attention away from nociceptive stimuli, but should also guarantee that attention is maintained on the processing of pain-unrelated information without being recaptured by the nociceptive stimuli. This model predicts that executive functions are involved in the control of selective attention by preserving goal priorities throughout the achievement of cognitive activities. ⋯ Results showed that, while novel nociceptive stimuli induced greater distraction than regular tactile stimuli in the control condition, the distractive effect was suppressed in the working memory condition. This suggests that actively rehearsing the feature of pain-unrelated and task-relevant targets successfully prevents attention from being captured by novel nociceptive distracters, independently of general task demands. Working memory can help to inhibit the involuntary capture of attention by pain by preserving cognitive goal priorities.
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Randomized Controlled Trial
An investigation of the development of analgesic tolerance to TENS in humans.
Transcutaneous electrical nerve stimulation (TENS) is a noninvasive modality used to control pain. Animal models show that repeated TENS application produces analgesic tolerance and cross-tolerance at spinal opioid receptors. The aim of the present investigation was to examine whether repeated application of TENS produces analgesic tolerance in humans. ⋯ These data suggest that repeated daily application of TENS results in a decrease in its hypoalgesic effect by the fifth day and that the tolerance-like effect to repeated TENS results from tolerance at centrally located opioid receptors. The lack of change in DNIC response suggests that TENS and DNIC utilize separate pathways to produce analgesia. Repeated high-frequency and low-frequency transcutaneous electrical nerve stimulation produce analgesic tolerance in humans by the fourth and fifth day of treatment, respectively.