Human Studies

HIV stigma may influence physical activity in people living with HIV (PLWH) and chronic pain. We prospectively examined the relationship between stigma, activity and chronic pain in a convenience sample of PLWH initiating antiretroviral therapy in an inner-city clinic in Johannesburg, South Africa. Participants wore accelerometers to measure daily duration and intensity of activity for 2 weeks. Stigma was assessed with the Revised HIV Stigma Scale. Participants [n = 81, 89% female, age mean (SD) 42 (8)] were active for a median of 7 h daily (IQR 5.2, 9.2), but at very low intensity, equivalent to a slow walk [median (IQR): 0.39 m s (0.33, 0.50)]. Duration and intensity of activity was not associated with stigma, even after controlling for age, self-assessed wealth, pain intensity and willingness to engage in physical activity (p-values > 0.05). As stigma did not associate with greater activity, drivers of sustained activity in South African PLWH remain unclear.

To assess whether alcohol intake is associated with the onset of migraine attacks up to 2 days after consumption in individuals with episodic migraine (EM).

As artificial intelligence technology advances, it is necessary to imitate various biological functions to complete more complex tasks. Among them, studies have been reported on the nociceptor, a critical receptor of sensory neurons that can detect harmful stimuli. Although a complex CMOS circuit is required to electrically realize a nociceptor, a memristor with threshold switching characteristics can implement the nociceptor as a single device. Here, we suggest a memristor with a Pt/HfO/TaO/TaN bilayer structure. This device can mimic the characteristics of a nociceptor including the threshold, relaxation, allodynia, and hyperalgesia. Additionally, we contrast different electrical properties according to the thickness of the HfO layer. Moreover, Pt/HfO/TaO/TaN with a 3 nm thick HfO layer has a stable endurance of 1000 cycles and controllable threshold switching characteristics. Finally, this study emphasizes the importance of the material selection and fabrication method in the memristor by comparing Pt/HfO/TaO/TaN with Pt/TaO/TaN, which has insufficient performance to be used as a nociceptor.

Low back pain contributes to an increasing global health burden exacerbated by unsustained improvements from current treatments. There is a need to develop, and test interventions to maintain initial improvements from low back pain treatments. One option is to implement a booster intervention. This study aimed to develop and test the feasibility of implementing a booster intervention delivered remotely to supplement the benefits from a complex intervention for chronic low back pain.

Depression, a prognostic factor for prescription opioid misuse commonly occurs in people with chronic non-cancer pain (CNCP). However, the mechanisms linking depression and prescription opioid misuse remain unclear. This study examined the potential mediating role of pain catastrophizing in the association between depressive symptoms and prescription opioid misuse risk, and impulsivity traits as possible moderators of these relationships. Individuals (N = 198; 77% women) with CNCP using prescription opioids participated in a cross-sectional online survey with validated measures of depression, pain catastrophizing, rash impulsiveness, reward drive, anxiety, pain severity and prescription opioid misuse. Meditation analyses with percentile-based bootstrapping examined pathways to prescription opioid use, controlling for age, sex, pain severity, and anxiety symptoms. Partial moderated mediation of the indirect effect of depressive symptoms on prescription opioid misuse risk through pain catastrophizing by rash impulsiveness and reward drive were estimated. Pain catastrophizing mediated depressive symptoms and prescription opioid misuse risk. Indirect effects were stronger when moderate to high levels of reward drive were included in the model. Findings suggest the risk of prescription opioid misuse in those experiencing depressive symptoms and pain catastrophizing is particularly higher for those higher in reward drive. Treatments targeting these mechanisms may reduce opioid misuse risk. Perspective: This article identifies reward drive as a potentially important factor increasing the effects of depression-related cognitive mechanisms on risk of prescription opioid misuse in those with CNCP. These findings could assist in personalizing clinical CNCP management to reduce the risks associated with opioid misuse.

Psychological flexibility (PF) is a model of well-being and daily functioning that is applied to chronic pain, and is the model behind Acceptance and Commitment Therapy (ACT). However, studies of PF in chronic pain are limited by the lack of a single measure capturing all facets. The Multidimensional Psychological Flexibility Inventory (MPFI) assesses all facets of PF and psychological inflexibility (PI) and could remedy this problem. The current study employs this measure. Adult participants with chronic pain (N = 404) were recruited online and completed the MPFI, other validated measures of PF/PI, and measures of pain, work and social adjustment, and depression, at two time points. The reliability, factor structure, and validity of the MPFI were assessed. Confirmatory factor analysis results demonstrated a good model fit for the proposed factor-and subscale structure. Correlations between MPFI and theoretically similar measures were moderate to strong, and correlations with pain intensity, pain interference, work-and social adjustment, and depression, were small to large. In this first examination of the potential utility of the MPFI within a chronic pain population, we found it to be valid and reliable. It should be noted that the MPFI was less predictive of outcomes compared with more established measures in most cases. Despite this, results from the wide range of variables available from the MPFI highlights the potential importance of aspects of PF and PI not previously emphasized, including the greater predictive utility of the inflexibility facets. Further use and study of the MPFI is recommended. ClinicalTrials.gov ID: NCT05050565 Perspective: This article presents a comprehensive examination of a self-report measure assessing all facets of psychological flexibility and inflexibility, in a chronic pain sample. The results support the role of facets not previously emphasized. Comprehensive assessment of PF and PI appears possible and is recommended depending on research questions being asked.

Observational studies suggest that 25-hydroxy vitamin D (25(OH)D) concentration is inversely associated with pain. However, findings from intervention trials are inconsistent. We assessed the effect of vitamin D supplementation on pain using data from a large, double-blind, population-based, placebo-controlled trial (the D-Health Trial). 21,315 participants (aged 60-84 years) were randomly assigned to a monthly dose of 60,000 IU vitamin D3 or a matching placebo. Pain was measured using the 6-item Pain Impact Questionnaire (PIQ-6), administered 1, 2 and 5 years after enrollment. We used regression models (linear for continuous PIQ-6 score and log-binomial for binary categorizations of the score, namely 'some or more pain impact' and 'presence of any bodily pain') to estimate the effect of vitamin D on pain. We included 20,423 participants who completed ≥1 PIQ-6. In blood samples collected from 3943 randomly selected participants (∼800 per year) the mean (SD) 25(OH)D concentrations were 77 (SD 25) and 115 (SD 30) nmol/L in the placebo and vitamin D groups, respectively. Most (76%) participants were predicted to have 25(OH)D concentration >50 nmol/L at baseline. The mean PIQ-6 was similar in all surveys (∼50.4). The adjusted mean difference in PIQ-6 score (vitamin D cf placebo) was 0.02 (95% CI, -0.20 to 0.25). The proportion of participants with some or more pain impact and with presence of bodily pain was also similar between groups (both prevalence ratios 1.01, 95% CI 0.99 to 1.03). In conclusion, supplementation with 60,000 IU of vitamin D3 per month had negligible effect on bodily pain.

Spinal cord stimulation (SCS) is considered an effective interventional nonpharmacologic treatment option for several chronic pain conditions. Here we present the effects of the novel evoked compound action potential (ECAP) controlled closed-loop (ECAP-CL) SCS system on long-term sleep quality outcomes from the EVOKE study.