The journal of pain : official journal of the American Pain Society
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Placebo treatments and healing rituals share much in common, such as the effects of expectancy, and have been used since the beginning of human history to treat pain. Previous mechanistic neuroimaging studies investigating the effects of expectancy on placebo analgesia have used young, healthy volunteers. Using functional magnetic resonance imaging (fMRI), we aimed to investigate the neural mechanisms by which expectancy evokes analgesia in older adults living with a chronic pain disorder and determine whether there are interactions with active treatment. ⋯ However, there were different patterns of changes in fMRI indices of brain activity associated with verum and sham treatment modalities specifically in the lateral prefrontal cortex. We also found that continuous electroacupuncture in knee OA patients can evoke significant regional coherence decreases in pain associated brain regions. Our results suggest that expectancy modulates the experience of pain in knee OA patients but may work through different pathways depending on the treatment modality and, we speculate, on pathophysiological states of the participants.
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Provoked vestibulodynia (PVD) is a chronic pelvic pain disorder affecting 16% of the female population. Neuroimaging studies have highlighted central abnormalities in PVD, similar to other chronic pelvic pain disorders, including brain regions involved in sensory processing and modulation of pain. The aim of the study was to determine alterations in the subvoxel, microstructural organization within tissues in PVD compared with healthy control participants (HCs) and a disease control group (irritable bowel syndrome [IBS]). ⋯ PVD subjects showed greater MD in the basal ganglia compared with HCs (higher MD in the internal capsule and pallidum) and IBS (higher MD in the putamen and pallidum). Increases in MD were associated with increased vaginal muscle tenderness and vulvar pain. The current findings highlight possible shared mechanisms between 2 different pelvic pain disorders, but also highlight the widespread alterations observed specifically in PVD compared with HCs.
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Vulvodynia is a idiopathic vulvovaginal pain condition that interferes with the sexual and mental health of affected couples. Research has underscored that psychological factors, such as anxiety and depression, are associated with its development and maintenance and related sexual impairment. However, the daily role of anxiety and depressive symptoms in the pain and sexuality outcomes of couples coping with vulvodynia is not well understood. ⋯ On days of sexual activity, when women reported higher depressive symptoms, they reported greater levels of sexual distress, and when partners reported higher anxiety and depressive symptoms, women as well as partners reported greater levels of sexual distress. Results suggest that daily anxiety and depressive symptoms play a role in women's experience of vulvodynia-related pain, women's sexual function, and the couple's sexual distress. Targeting daily anxiety and depressive symptoms could enhance the efficacy of psychological interventions for vulvodynia.
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Placebo and nocebo mechanisms can lead to clinically significant modulation of pain. Although learning is considered to be the broad mechanism underlying placebo analgesia as well as nocebo hyperalgesia, critical differences have emerged in their specific mechanisms. One of the most interesting of these is that whereas placebo analgesia seems to be relatively short-lived, nocebo hyperalgesia appears more resistant to extinction, often persisting indefinitely. ⋯ The conditioning procedure successfully induced placebo analgesia as well as nocebo hyperalgesia in the relevant groups, with nocebo hyperalgesia outlasting placebo analgesia, confirming nocebo hyperalgesia's resistance to extinction. Most interestingly, nocebo treatment led to heightened anticipatory anxiety ratings and autonomic arousal. Further, autonomic arousal completely mediated the effect of nocebo versus placebo training on extinction, suggesting that heightened autonomic arousal may be an important mechanism in the persistence of nocebo hyperalgesia.
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The analgesic effect of social support is proposed as a function of social support modulating perceived threat of painful stimuli. In the current study, we directly examined the social buffering effect in the context of the threat of pain. Eighteen healthy participants were subjected to the threat of pain while they held the hand of a close other, a stranger, or not at all. ⋯ Interestingly, decreased heart rate and frontal theta in the close other hand-holding condition were uniquely associated with greater pain reduction during subsequent nociceptive stimulation. Neural changes were source-localized to the insular cortex and the rostral-ventral portions of anterior cingulate cortex, regions involved in the processing of threat and pain. Together, our data build upon work to date linking social support to pain by showing autonomic and neurophysiological changes associated with pain reduction.