Pain
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Although we know chronic pain (CP) affects approximately 30% of people in developed countries, data from Latin America are scarce. Moreover, prevalence of specific CP conditions, such as chronic noncancer pain (CNCP), fibromyalgia (FM), and neuropathic pain (NP), is unknown. To estimate them in Chile, we prospectively enrolled 1945 participants (61.4% women and 38.6% men), aged 38 to 74 years, from an agricultural town who answered a Pain Questionnaire, the Fibromyalgia Survey Questionnaire, and Douleur Neuropathique 4 (DN4) to identify CNCP, FM, and NP, respectively. ⋯ Female sex, fewer school years, and depressive symptoms were associated with FM and NP, whereas diabetes was only associated with NP. We standardized the results from our sample against the whole Chilean population and found no significant difference to our crude estimates. This is in line with studies from developed countries, highlighting the idea that despite genetic and environmental differences, the conditions that confer risk to CNCP remain stable.
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As pain is processed by an extensive network of brain regions, the structural status of the brain may affect pain perception. We aimed to study the association between gray matter volume (GMV) and pain sensitivity in a general population. We used data from 1522 participants in the seventh wave of the Tromsø study, who had completed the cold pressor test (3°C, maximum time 120 seconds), undergone magnetic resonance imaging (MRI) of the brain, and had complete information on covariates. ⋯ The effect remained significant after additional adjustment for chronic pain (HR 0.84, 95% CI 0.72-0.97) or depression (HR 0.82, 95% CI 0.71-0.94). In post hoc analyses, positive associations between standardized GMV and pain tolerance were seen in most brain regions, with larger effect sizes in regions previously shown to be associated with pain. In conclusion, our findings indicate that larger GMV is associated with longer pain tolerance in the general population.
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Induced pluripotent stem cells (iPSCs) have enabled the generation of various difficult-to-access cell types such as human nociceptors. A key challenge associated with human iPSC-derived nociceptors (hiPSCdNs) is their prolonged functional maturation. While numerous studies have addressed the expression of classic neuronal markers and ion channels in hiPSCdNs, the temporal development of key signaling cascades regulating nociceptor activity has remained largely unexplored. ⋯ However, effective inhibition of forskolin-induced PKA-II activation by opioid receptor agonists required 70 days of in vitro differentiation. Our results identify a pronounced time difference between early expression of functionally important ion channels and emergence of regulatory metabotropic sensitizing and desensitizing signaling only at advanced stages of in vitro cultivation, suggesting an independent regulation of ionotropic and metabotropic signaling. These data are relevant for devising future studies into the development and regulation of human nociceptor function and for defining time windows suitable for hiPSCdN-based drug discovery.
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Adverse childhood experiences (ACEs) are associated with altered ongoing and evoked pain experiences, which have scarcely been studied for the peripartum period. We aimed to investigate how ACEs affect pain experience in pregnancy and labor. For this noninterventional trial with a short-term follow-up, pregnant women were divided into a trauma group (TG) with ACEs (n = 84) and a control group (CG) without ACEs (n = 107) according to the Childhood Trauma Questionnaire. ⋯ While PPTs increased through delivery in the CG (clinical CPM), and this PPT change was positively correlated with the experimental CPM ( r = 0.55), this was not the case in the TG. The association of ACEs with increased peripartal pain affect and heightened risk for preexisting back pain suggest that such women deserve special care. The dissociation of impaired clinical CPM in women with ACEs and normal prepartum experimental CPM implies at least partly different mechanisms of these 2 manifestations of endogenous pain controls.
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Observational Study
Fibromyalgia predicts increased odds of pain-related addiction exacerbation among individuals with pain and opioid use disorder.
Fibromyalgia and opioid use disorder (OUD) are highly impactful chronic illnesses with substantially overlapping psychosocial, biological, and clinical features. Little previous research has examined interactions between fibromyalgia and OUD. Limiting such research has been the previous requirement of a clinical examination to diagnose fibromyalgia. ⋯ Although all participants had pain, those with fibromyalgia demonstrated significantly greater odds of acknowledging pain-related OUD exacerbations. Pain-related OUD Exacerbation Scale was found to have a single-factor solution, strong internal consistency, and construct validity. This study provides first evidence of fibromyalgia as a risk factor for pain-related exacerbation of OUD and introduces a new scale with promising psychometric properties to measure pain-related OUD exacerbation.