Pain
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Although animal models have consistently demonstrated acute pain inhibitory effects of nicotine and tobacco, human experimental studies have yielded mixed results. The main goal of this meta-analysis was to quantify the effects of nicotine/tobacco administration on human experimental pain threshold and tolerance ratings. A search of PubMed and PsycINFO online databases identified 13 eligible articles, including k = 21 tests of pain tolerance (N = 393) and k = 15 tests of pain threshold (N = 339). ⋯ Current smoking has been associated with more severe chronic pain and physical impairment. Acute nicotine-induced analgesia could make smoking more rewarding and harder to give up. Future research should use dynamic measures of experimental pain reactivity and further explore biopsychosocial mechanisms of action.
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Transient receptor potential vanilloid 1 (TRPV1) is a polymodal receptor activated by capsaicin, heat, and acid, which plays critical roles in thermosensation and pain. In addition, TRPV1 also contributes to multiple pathophysiological states in respiratory, cardiovascular, metabolic, and renal systems. These contributions are further supported by evidence that variations in the human TRPV1 (hTRPV1) gene are associated with various physiological and pathological phenotypes. ⋯ Our results demonstrated that the 5 SNPs differentially affected functional properties of hTRPV1 in an agonist-dependent manner. Based upon the directionality of change of each phenotype and cumulative changes in each SNP, we classified the 5 SNPs into 3 presumptive functional categories: gain of function (hTRPV1 Q85R, P91S, and T469I), loss of function (I585V), and mixed (M315I). These results reveal a spectrum of functional variation among common hTRPV1 polymorphisms in humans and may aid mechanistic interpretation of phenotypes associated with nonsynonymous hTRPV1 SNPs under pathophysiological conditions.
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The International Classification of Diseases (ICD) and the Diagnostic and Statistical Manual (DSM) are routinely used in diagnosing illicit substance use disorders, but for people taking prescribed opioids they remain controversial. In pain medicine, the concept of "Addiction" is preferred with reduced emphasis on tolerance and withdrawal. This article examines the prevalence and characteristics of pharmaceutical opioid dependence/disorder according to ICD, DSM, and the pain medicine concept of "Addiction," among chronic noncancer pain (CNCP) patients prescribed opioids. ⋯ Participants meeting the criteria for "Addiction" only were older, less likely to engage in nonadherent behaviours, self-reported fewer problems or concerns with their medication, and had lower rates of psychological distress than those who also met the DSM-5 and ICD-11 criteria. The definition of "Addiction" captures a larger group of patients than other classification systems and includes people with fewer "risk" behaviours. Despite removal of tolerance and withdrawal for prescribed opioid use for DSM-5, we found that "Addiction" was more closely related to an ICD-11 diagnosis of pharmaceutical opioid dependence.
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Activity pacing is frequently included among the strategies provided to individuals with chronic pain to manage pain and improve functioning. Individuals with chronic pain may, however, limit their use of activity pacing because they perceive significant obstacles to its use. This study describes the development of a measure to assess obstacles to activity pacing and examines the relationship of this measure to activity patterns and functioning. ⋯ Fewer obstacles were identified by both men and women after treatment, and these changes were related to modest changes in activity patterns and functioning. The present results identify a number of obstacles that may limit the use of activity pacing by individuals with chronic pain. Treatment may result in a decrease in the number of obstacles identified, and this change is related to changes in the individual's activity pattern and psychosocial functioning.
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Randomized Controlled Trial
Brief Time-Based Activity Pacing Instruction as a Singular Behavioral Intervention was not Effective in Participants with Symptomatic Osteoarthritis.
Osteoarthritis (OA) of the lower extremities is a prevalent cause of disability in which symptoms interfere with mobility and activity participation. Behavioral self-management for OA symptomatology is commonly recommended; but these interventions are underutilized, unstandardized in application, and at times, unavailable in the context of clinical care. For people with chronic pain, rehabilitation professionals may select to apply activity pacing instruction as one behavioral strategy to manage symptoms. ⋯ Using linear mixed models, Western Ontario and McMaster Universities Osteoarthritis Index pain scores changed over time, decreasing the most in the general and usual care groups; only the usual care group had decreased pain over 6 months. The tailored and general activity pacing groups reported higher frequency of pacing behaviors than the usual care group at 10 weeks, but pacing was not sustained at 6 months. This trial does not support the use of time-based pacing as a singular behavioral strategy for people with knee or hip OA.