The journal of pain : official journal of the American Pain Society
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Clinical Trial
Cortico-brainstem mechanisms of biased perceptual decision-making in the context of pain.
Prior expectations can bias how we perceive pain. Using a drift diffusion model, we recently showed that this influence is primarily based on changes in perceptual decision-making (indexed as shift in starting point). Only during unexpected application of high-intensity noxious stimuli, altered information processing (indexed as increase in drift rate) explained the expectancy effect on pain processing. ⋯ Our findings suggest involvement of the PAG in both decision-making bias and altered information processing to implement expectancy effects on pain. PERSPECTIVE: Modulation of pain through expectations has been linked to changes in perceptual decision-making and altered processing of afferent information. Our results suggest involvement of the dorsolateral prefrontal cortex, amygdala, and periaqueductal gray in these processes.
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When pain persists beyond healing time and becomes a "false alarm" of bodily threat, protective strategies, such as avoidance, are no longer adaptive. More specifically, generalization of avoidance based on conceptual knowledge may contribute to chronic pain disability. Using an operant robotic-arm avoidance paradigm, healthy participants (N = 50), could perform more effortful movements in the threat context (eg, pictures of outdoor scenes) to avoid painful stimuli, whereas no pain occured in the safe context (eg, pictures of indoor scenes). ⋯ In contrast, the fear-potentiated startle response was not modulated by context. PERSPECTIVE: This article provides evidence for contextual modulation of avoidance behavior and its generalization to novel exemplars of the learned categories based on conceptual relatedness. Our findings suggest that category-based generalization is a plausible mechanism explaining why patients display avoidance behavior in novel situations that were never directly associated with pain.
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The majority of individuals with temporomandibular disorders (TMD) experience sleep disturbance, which can maintain and exacerbate chronic pain. However, the factors underlying the sleep-pain link have not been fully elucidated, especially beyond the laboratory. Sleep deprivation can induce threat interpretation bias, as well as impairment in positive affective functioning. ⋯ Reducing exaggerated daily pain expectancy and up-regulating positive affect may be important intervention targets for disengaging the sleep-pain link among individuals with co-occurring TMD and sleep disturbance. PERSPECTIVE: The daily link between previous night sleep duration and next day pain severity is mediated by morning pain expectancy and positive affect among women with temporomandibular disorder and sleep disturbance. Reducing pain expectancy and increasing positive affect may serve an important role in improving self-management of chronic pain.
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Review Meta Analysis
Prevalence, incidence, and factors associated with non-specific chronic low back pain in community-dwelling older adults aged 60 years and older: A systematic review and meta-analysis.
Chronic low back pain (CLBP) is common among older adults. This systematic review aimed to summarize: (1) the prevalence and incidence of CLBP in older adults, and (2) demographic, psychological, and clinical factors positively/negatively associated with prevalence/incidence of CLBP among older adults. Four databases were searched to identify relevant publications. ⋯ Given the aging population and limited information regarding risk factors for CLBP in older adults, future high-quality prospective studies should identify relevant risk factors to help develop proper preventive and treatment strategies. PERSPECTIVE: Despite the high prevalence of non-specific chronic low back pain among older adults, there is only very limited to limited evidence regarding factors associated with a higher prevalence of chronic low back pain in this population. Given the aging population, high-quality prospective studies are warranted to address this gap.
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Randomized Controlled Trial
Impact of bifrontal home-based transcranial direct current stimulation in pain catastrophizing and disability due to pain in fibromyalgia: a randomized, double-blind sham-controlled study.
This randomized, double-blind trial tested the hypothesis that 20 sessions of home-based anodal(a)-transcranial direct current stimulation (tDCS) (2mA for 20 minutes) bifrontal, with anodal on the left dorsolateral prefrontal cortex (l-DLPFC) would be better than sham-(s)-tDCS to reduce scores on Pain Catastrophizing Scale and disability-related to pain assessed by the Profile of Chronic Pain: Screen (primary outcomes). Secondary outcomes were depressive symptoms, sleep quality, heat pain threshold , heat pain tolerance , and serum brain-derived-neurotrophic-factor (BDNF). Forty-eight women with fibromyalgia, 30 to 65 years-old were randomized into 2:1 groups [a-tDCS (n = 32) or s-tDCS (n = 16)]. ⋯ In contrast, the a-tDCS impact on reducing the disability-related to pain at the treatment end was positively associated with a reduction in the serum BDNF and improvement of depressive symptoms, sleep quality and pain catastrophizing symptoms. PERSPECTIVE: Home-based bifrontal tDCS with a-tDCS on the l-DLPFC are associated with a moderate effect size (ES) in the following outcomes: 1) Decreased rumination and magnification of pain catastrophizing. 2) Improved the disability for daily activities due to fibromyalgia symptoms. Overall, these findings support the feasibility of self-applied home-based tDCS on DLPFC to improve fibromyalgia symptoms.