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The United States (US) population consumes an estimated 68% of the world's prescribed opioids each year, and over 2 million adults in the US suffer from an opioid use disorder. Although chronic pain populations are among the highest risk segments of the general population for opioid misuse and dependence, there is little understanding of individual risk characteristics that may contribute to greater risk for these outcomes among this group. The present investigation explored the concurrent role of anxiety sensitivity and pain intensity and their interaction in relation to opioid misuse and dependence among 429 adults with chronic pain (73.9% female, M = 38.32 years, SD = 11.07). Results revealed that both anxiety sensitivity and pain intensity were associated with opioid misuse and dependence. There was no evidence of an interaction for either outcome. Post-hoc analyses indicated that of the lower-order anxiety sensitivity facets, physical and mental incapacitation concerns contributed to variance in opioid misuse and only mental incapacitation concerns contributed to variance in opioid dependence. Overall, the current findings suggest the importance of assessing anxiety sensitivity in screening for opioid-related problems among persons with chronic pain, as it may represent a distinct pathway to poorer opioid-related outcomes among this group.
Learn More >As a rite of passage to womanhood, 2 million girls undergo female genital circumcision (FGC) – the tradition of cutting, and often removing parts of the vulva – every year. The current study is the first to focus on the connection between peripheral nerve damage and chronic neuropathic pain in women with FGC. We used mixed methods – quantitative, qualitative and physiological – to study chronic pain in Somali-Canadian women (N = 14). These women have the most extensive form of FGC, which includes removal of the glans clitoris, labia minora, medial portion of the labia majora, and stitching together the remaining parts of the labia majora. Our results indicate a multifaceted pain experience in women with FGC. Although they report good overall health and very low pain levels on the short form of the McGill Pain Questionnaire, pressure-pain quantitative sensory testing of the vulvar region applied through vulvalgesiometers shows pain thresholds consistent with those reported by women with chronic vulvar pain. Furthermore, qualitative interviews reveal a considerable amount of often debilitating pain in daily life. These results challenge the use of assessment tools offering elicited verbal pain language and highlight the importance of culturally sensitive ways of conceptualizing, measuring and managing pain.
Learn More >Opioid therapies for chronic pain are undermined by many adverse side effects that reduce their efficacy and lead to dependence, abuse, reduced quality of life, and even death. We have recently reported that sphingosine-1-phosphate (S1P) 1 receptor (S1PR1) antagonists block the development of morphine-induced hyperalgesia and analgesic tolerance. However, the impact of S1PR1 antagonists on other undesirable side effects of opioids, such as opioid-induced dependence, remains unknown. Here, we demonstrate that naloxone-precipitated morphine withdrawal in mice altered de novo sphingolipid metabolism in the dorsal horn of the spinal cord and increased S1P that accompanied the manifestation of several withdrawal behaviors. Blocking de novo sphingolipid metabolism with intrathecal administration of myriocin, an inhibitor of serine palmitoyltransferase, blocked naloxone-precipitated withdrawal. Noteworthy, we found that competitive (NIBR-15) and functional (FTY720) S1PR1 antagonists attenuated withdrawal behaviors in mice. Mechanistically, at the level of the spinal cord, naloxone-precipitated withdrawal was associated with increased glial activity and formation of the potent inflammatory/neuroexcitatory cytokine interleukin-1β (IL-1β); these events were attenuated by S1PR1 antagonists. These results provide the first molecular insight for the role of the S1P/S1PR1 axis during opioid withdrawal. Our data identify S1PR1 antagonists as potential therapeutics to mitigate opioid-induced dependence and support repurposing the S1PR1 functional antagonist FTY720, which is FDA-approved for multiple sclerosis, as an opioid adjunct.
Learn More >Individuals with chronic pain conditions often report movement as exacerbating pain. An increasing number of researchers and clinicians have recognized the importance of measuring and distinguishing between movement-evoked pain (MEP) and pain at rest as an outcome. This scoping review maps the literature and describes MEP measurement techniques.
Learn More >Pathophysiologic mechanisms underpinning ongoing pain in whiplash associated disorder (WAD) are not well understood, however alterations in brain morphology and function have been observed in this population, as well as in other chronic pain conditions. This study investigated metabolite profiles of brain regions in people with chronic WAD compared with controls.
Learn More >The study of Patient-Controlled Analgesia (PCA) behaviors has led to greater understanding of factors that affect the pain experience. Although PCA behaviors can be influenced by cues to medication availability, no studies have examined the effects of such cues in pediatric populations.
Learn More >Pain is prevalent among youth with sickle cell disease (SCD). However, previous research has been limited by small sample sizes, and lacked examinations of developmental differences in pain – which are critical to minimizing the development of chronic pain as youth transition into adulthood. The primary aim of the current study was to compare pain and pain interference across four developmental groups in a large sample of youth with SCD. The secondary aim was to identify risk factors for greater pain and pain interference.
Learn More >Chronic pain is highly prevalent in the United States, impacting 28.4% of the adult population, or 69.6 million people, as of 2016. Chronic pain is often associated with anxiety, depression, and restrictions in mobility and daily activities, substantially reducing quality of life. Analgesics, especially opioids, are one of the primary pharmaceutical treatment methods for chronic pain. However, prescription opioid misuse and abuse has become increasingly prevalent and concerning, prompting the need for research into alternative treatment methods which avoid the side effects of traditional treatments. Chronic pain is, in part, thought to be the result of oxidative stress and inflammation, and clinical research has indicated links between these conditions and diet. Thus, dietary interventions are a particularly promising therapeutic treatment for chronic pain, with numerous studies suggesting that diet has a noticeable effect on pain as far down as the cellular level. In this review article, data from a number of clinical trials assessing the effect of three diets-antioxidant-rich, low-carbohydrate, and Mediterranean-on oxidative stress and inflammation is compiled and discussed in the context of chronic pain. Clinical data suggests that low-carbohydrate diets and Mediterranean diets both are especially promising dietary interventions.
Learn More >Sleep disturbance is often comorbid with chronic pain disorders, with emerging evidence suggesting a stronger effect of sleep disturbance on pain than vice versa; however, few studies have evaluated the long-term associations between sleep disturbance and pain. This study was to examine the associations of sleep disturbance with knee pain severity, number of painful sites (NPS) and persistent pain in a 10.7-year cohort study.
Learn More >Inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS), historically considered as regional gastrointestinal disorders with heightened colonic sensitivity, are increasingly recognized to have concurrent dysfunction of other visceral and somatic organs, such as urinary bladder hyperactivity, leg pain, and skin hypersensitivity. The inter-organ sensory crosstalk is, at large, termed 'cross-organ sensitization'. These organs, anatomically distant from one another, physiologically interlock through projecting their sensory information into dorsal root ganglia (DRG) and then the spinal cord for integrative processing. The fundamental question of how sensitization of colonic afferent neurons conveys nociceptive information to activate primary afferents that innervate distant organs remains ambiguous. In DRG, primary afferent neurons are surrounded by satellite glial cells (SGCs) and macrophage accumulation in response to signals of injury to form neuron-glia-macrophage triad. Astrocytes and microglia are major resident non-neuronal cells in the spinal cord to interact, physically and chemically, with sensory synapses. Cumulative evidence gathered so far indicate the indispensable roles of paracrine/autocrine interactions among neurons, glial cells, and immune cells in sensory cross-activation. Dichotomizing afferents, sensory convergency in the spinal cord, spinal nerve comingling, and extensive sprouting of central axons of primary afferents each has significant roles in the process of cross-organ sensitization, however, more results are required to explain their functional contributions. DRG that are located outside the blood-brain-barrier and reside upstream in the cascade of sensory flow from one organ to the other in cross-organ sensitization could be safer therapeutic targets to produce less central adverse effects.
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