Predictors of participation in online self-management programs: A longitudinal observational study

PURPOSE/OBJECTIVE

Lack of patient participation and engagement remains a barrier to implementing effective online self-management and behavioral health interventions. Identifying patient characteristics associated with engagement rates may lead to interventions that improve engagement in traditional and online self-management programs. In this study, two online self-management and recovery programs were evaluated to identify factors that predict patient engagement.

RESEARCH METHOD/DESIGN

Predictors were collected in a questionnaire at baseline before 435 participants started either of the two interventions. One or two online lessons were completed per week with seven or eight total lessons to complete in each program, and each lesson took about 20-30 min to finish. Full patient engagement was defined as completing all lessons and assessments in the program and partial engagement as attempting at least one lesson or assessment.

RESULTS

Predictors of full patient engagement were self-rated confidence in completing the program or being over 60 years of age. Predictors of at least partial patient engagement were experienced ordering online or being over 50 years of age.

CONCLUSIONS/IMPLICATIONS

Identifying profiles of individuals who predict poor engagement may improve implementation and the health outcomes of intervention programs. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Sleep Disruption Moderates the Daily Dynamics of Affect and Pain in Sickle Cell Disease

Persons with sickle cell disease (SCD) often experience pain that can interfere with quality of life and daily activities. Pain can modulated by affect and sleep continuity; however, few studies have explored how these factors complementarily influence pain in adults with SCD. The study aims were to investigate 1) whether pain levels were heightened on days characterized by low positive affect and high negative affect, and 2) whether the relationship between affect and pain was intensified following nights of disrupted sleep. Adults with SCD (N = 25) completed ecological momentary assessments and daily sleep diaries. Mixed models were used to analyze the main and interactive effects of daily affect (positive affect and negative affect) and sleep disruption (wake after sleep onset and frequency of awakenings) on both daily average pain and daily maximum pain. Results suggested that daily average pain and maximum pain tended to be higher on days of low positive affect and high negative affect. Furthermore, the frequency of nocturnal awakenings moderated the relationship between positive affect and pain. On days where there were higher frequencies of nocturnal awakenings, low positive affect was associated with both average and maximum pain; however, this association was not observed with lower frequencies of nocturnal awakenings. The association between negative affect and maximum pain was also stronger at higher levels of awakenings. Results highlight the relevance of adjunctive interventions that target affect among populations with SCD and further suggest that sleep continuity may further facilitate these interventions, highlighting the importance of multimodal treatments. PERSPECTIVE: This study examined the effects of affect and sleep on pain among adults with sickle cell disease (SCD). Higher pain occurred on days of low positive affect and high negative affect, particularly following nights of more frequent awakenings. These findings emphasize the importance of addressing affect and sleep in SCD treatment.

Perioperative insomnia trajectories and functional outcomes after total knee arthroplasty

ABSTRACT

Longitudinal total knee arthroplasty (TKA) studies indicate that a substantial percentage of patients continue to experience clinically significant pain and functional impairment after surgery. Insomnia has been associated with poorer surgical outcomes; however, previous work has largely focused on long-term postsurgical insomnia. This study builds on previous work by examining sleep and pain outcomes about perioperative insomnia trajectories. Insomnia symptoms (using the Insomnia Severity Index) during the acute perioperative period (2 weeks pre-TKA to 6 weeks post-TKA) were used to classify participants into perioperative insomnia trajectories: (1) No Insomnia (ISI < 8), (2) New Insomnia (baseline < 8; postoperative ≥ 8 or ≥6-point increase), (3) Improved Insomnia (baseline ≥ 8, postoperative < 8 or ≥6-point decrease), and (4) Persistent Insomnia (ISI ≥ 8). Insomnia, pain, and physical functioning were assessed in participants with knee osteoarthritis (n = 173; M age = 65 ± 8.3, 57.8% female) at 5 time points: 2 weeks pre-TKA, post-TKA: 6 weeks, 3 months, 6 months, and 12 months. Significant main effects were seen for insomnia trajectory and time, and trajectory-by-time interactions for postoperative insomnia, pain severity, and physical functioning ( P' s < 0.05). The Persistent Insomnia trajectory had the worst postoperative pain at all follow-ups and marked insomnia and physical functioning impairment post-TKA ( P' s < 0.05). The New Insomnia trajectory had notable long-term insomnia (6 weeks to 6 months) and acute (6 weeks) postoperative pain and physical functioning ( P' s < 0.05). Findings indicated a significant relationship between perioperative insomnia trajectory and postoperative outcomes. Results of this study suggest that targeting presurgical insomnia and preventing the development of acute postoperative insomnia may improve long-term postoperative outcomes, with an emphasis on persistent perioperative insomnia due to poorer associated outcomes.

Presurgical sleep and pain behaviors predict insomnia symptoms and pain after total knee arthroplasty: a 12-month longitudinal, observational study

OBJECTIVE

Up to 40% of individuals who undergo total knee arthroplasty (TKA) experience some degree of pain following surgery. Presurgical insomnia has been identified as a predictor of postsurgical pain; however, modifiable presurgical behaviors related to insomnia have received minimal attention. The objective of the present study was to develop a 2-item sleep and pain behavior scale (SP2) to investigate a maladaptive sleep and pain behavior and is a secondary analysis of a larger, parent study.

METHODS

Patients (N = 109) completed SP2 at baseline and 12 months and questionnaires assessing sleep and pain at baseline (pre-TKA), 6 weeks, 3, 6, and 12 months post-TKA. SP2 demonstrated adequate preliminary psychometric properties.

RESULTS

As hypothesized, even after controlling for baseline insomnia, pain, anxiety and other covariates, baseline SP2 predicted insomnia symptom severity at 6 weeks (β = 2.828), 3 (β = 2.140), 6 (β = 2.962), and 12 months (β = 1.835) and pain at 6 weeks (β = 6.722), 3 (β = 5.536), and 6 months (β = 7.677) post-TKA (P < .05). Insomnia symptoms at 6-weeks post-TKA mediated the effect of presurgical SP2 on pain at 3 (95% CI: 0.024-7.054), 6 (95%CI: 0.495-5.243), and 12 months (95% CI: 0.077-2.684).

CONCLUSIONS

This provides preliminary evidence that patients who cope with pain by retiring to their bed and bedroom have higher rates of post-surgical insomnia and pain and supports efforts to target this maladaptive sleep and pain behavior to reduce postsurgical pain.

Medium- and Long-Term Effects of Insomnia Severity and Circadian Preference on Pain and Emotional Distress Among Individuals With Chronic Pain

Studies have identified insomnia as having significant influence on chronic pain. A rising body of research has also underscored the association between eveningness and chronic pain. However, co-assessment of insomnia and eveningness in the context of chronic pain adjustment has been limited. The present study sought to investigate the effects of insomnia and eveningness on pain severity, pain interference, and emotional distress (ie, depressive and anxiety symptoms) over nearly 2 years among adults with chronic pain in the U.S. Adults with chronic pain (N = 884) were surveyed 3 times via Amazon's MTurk online crowdsourcing platform: baseline, 9-month follow-up, and 21-month follow-up. Path analysis was conducted to examine the effects of baseline insomnia severity (Insomnia Severity Index) and eveningness (Morningness and Eveningness Questionnaire), as well as their moderating effects on outcomes. Controlling for select sociodemographic variables and baseline outcome levels, greater insomnia severity at baseline was associated with worsening of all of the pain-related outcomes at 9-month follow-up, and pain interreference and emotional distress at 21-month follow-up. We did not find evidence that evening types are at a higher risk of experiencing worsening pain-related outcomes over time compared to morning and intermediate types. There were also no significant insomnia severity and eveningness moderation effects on any outcome. Our findings suggest that insomnia is a more robust predictor of changes in pain-related outcomes as compared to eveningness. Treatment of insomnia can be important in chronic pain management. Future studies should evaluate the role of circadian misalignment on pain using more accurate biobehavioral makers. PERSPECTIVE: This study examined the effects of insomnia and eveningness on pain and emotional distress in a large sample of individuals with chronic pain. Insomnia severity is a stronger predictor of changes in pain and emotional distress than eveningness, highlighting insomnia as an important clinical target for chronic pain management.

Race differences in pain and pain-related risk factors among former professional American-style football players

ABSTRACT

The burden of pain is unequal across demographic groups, with broad and persisting race differences in pain-related outcomes in the United States. Members of racial and ethnic minorities frequently report more pervasive and severe pain compared with those in the majority, with at least some disparity attributable to differences in socioeconomic status. Whether race disparities in pain-related health outcomes exist among former professional football players is unknown. We examined the association of race with pain outcomes among 3995 former professional American-style football players who self-identified as either Black or White. Black players reported more intense pain and higher levels of pain interference relative to White players, even after controlling for age, football history, comorbidities, and psychosocial factors. Race moderated associations between several biopsychosocial factors and pain; higher body mass index was associated with more pain among White but not among Black players. Fatigue and psychosocial factors were more strongly related to pain among Black players relative to White players. Collectively, the substantial social and economic advantages of working as a professional athlete did not seem to erase race-related disparities in pain. We highlight an increased burden of pain among elite Black professional football players and identify race-specific patterns of association between pain and biopsychosocial pain risk factors. These findings illuminate potential future targets of interventions that may serve to reduce persistent disparities in the experience and impact of pain.

Within-subject, double-blind, randomized, placebo-controlled evaluation of combining the cannabinoid dronabinol and the opioid hydromorphone in adults with chronic pain

The potential synergistic effects of combining cannabinoids and opioids for analgesia has received considerable attention. No studies to date have evaluated this combination in patients with chronic pain. The present study aimed to evaluate the combined analgesic and drug effects of oral opioid (hydromorphone) and delta-9-tetrahydrocannabinol (dronabinol), as well as their effects on physical and cognitive functioning, and human abuse potential (HAP) outcomes among individuals with knee osteoarthritis (KOA). This was a within-subject, double-blind, randomized, placebo-controlled study. Participants (N = 37; 65% women; mean age = 62) diagnosed with knee osteoarthritis of ≥3/10 average pain intensity were included. Participants received (1) placebo-placebo, (2) hydromorphone (4 mg)-placebo; (3) dronabinol (10 mg)-placebo, and (4) hydromorphone (4 mg)-dronabinol (10 mg). Clinical and experimentally-induced pain, physical and cognitive function, subjective drug effects, HAP, adverse events, and pharmacokinetics were evaluated. No significant analgesic effects were observed for clinical pain severity or physical functioning across all drug conditions. Little enhancement of hydromorphone analgesia by dronabinol was observed on evoked pain indices. While subjective drug effects and some HAP ratings were increased in the combined drug condition, these were not significantly increased over the dronabinol alone condition. No serious adverse events were reported; hydromorphone produced more mild adverse events than placebo, but hydromorphone + dronabinol produced more moderate adverse events than both placebo and hydromorphone alone. Only hydromorphone impaired cognitive performance. Consistent with laboratory studies on healthy adults, the present study shows minimal benefit of combining dronabinol (10 mg) and hydromorphone (4 mg) for analgesia and improving physical functioning in adults with KOA.

Within subject, double blind, examination of opioid sensitivity in participant-reported, observed, physiologic, and analgesic outcomes

Background

Inter-individual differences in opioid sensitivity may underlie different opioid risk profiles but have often been researched in persons who have current or past opioid use disorder or physical dependence. This study examined how opioid sensitivity manifests across various assessments of opioid effects in a primarily opioid-naïve population.

Procedures

Data were harmonized from two within-subject, double-blind trials wherein healthy participants (N = 123) received placebo and 4 mg oral hydromorphone. Demographics, self-report ratings, observer ratings, physiological, and cold pressor measures were collected. Participants were categorized as being responsive or nonresponsive to the opioid dose tested and compared using mixed-models, Pearson product correlations, and paired t-tests.

Findings

Participants were 49.6% female, mean 33.0 (SD=9.3) years old, and 44.7% Black/African American and 41.5% White, with 89.4% reporting no prior exposure to opioids. Within-subject sensitivity to opioids varied depending on the measure. One in five participants did not respond subjectively to the 4 mg hydromorphone dose based on their "Drug Effects" rating. Persons who were responsive showed more evidence of drug-dependent effects than did persons who were not responsive on ratings of Bad Effects (p= .03), feeling High (p= .01), Nausea (p= .03), pupil diameter (p< 0.01), and on the circular lights task (p< 0.001).

Conclusions

This study provides initial evidence that the experience of opioids may be domain specific. Data suggest potentially clinically meaningful differences exist regarding opioid response patterns, evident following one dose among opioid inexperienced individuals.

Individual Dimensions of Pain Catastrophizing Do Not Mediate the Effect of Sociodemographic and Psychological Factors on Chronic Orofacial Pain Severity, Interference, and Jaw Limitation: A Structural Equation Modeling Approach

Pain catastrophization (PC), involving rumination, magnification, and helplessness, can be viewed as a coping strategy associated with chronic pain. PC is considered a driving force in mediating pain-related outcomes, but it is still unclear whether PC mediates the relationship between psychological and sociodemographic factors with chronic pain when considered in a single model. Using baseline data from a parent study, this study examined the effect of positive and negative psychological and sociodemographic factors on pain severity, interference, and jaw limitation mediated by the PC dimensions in a sample of 397 temporomandibular disorder (TMD) participants using structural equation modeling (SEM). SEM revealed that pain severity regressed on age, sex, education, and income; interference regressed on positive and negative psychological factors, education, and income; and jaw limitation regressed on age. The PC dimensions did not individually mediate these relationships. Although they jointly mediated the relationships between negative psychological factors and pain severity and between age and pain interference, the effect size was small, suggesting that PC is not a critical factor in mediating TMD pain outcomes. Reducing negative cognitions, not just PC, may be of greatest benefit to the most vulnerable TMD populations. PERSPECTIVE: This study examines sociodemographic and psychological factors that affect orofacial pain, finding that the pain catastrophizing dimensions do not mediate these relationships. Understanding which factors most strongly affect pain outcomes will help identify targets for intervention to produce the greatest benefit for the most vulnerable persons suffering from pain.

Change in Pain During Physical Activity Following Total Knee Arthroplasty: Associations With Improved Physical Function and Decreased Situational Pain Catastrophizing

Background and Objectives

Knee osteoarthritis is one of the primary causes of chronic pain among older adults and because of the aging population, the number of total knee arthroplasties (TKAs) performed is exponentially increasing. While pain reduction is a goal of TKA, movement-evoked pain is rarely assessed pre- and post-TKA. We characterized the distributions of change in pain, function, and situational catastrophizing in patients from presurgery to 3 months postsurgery and explored associations among these pre-post changes.

Research Design and Methods

This prospective study longitudinally assessed movement-evoked pain, function, and situational catastrophizing in patients with knee osteoarthritis (N = 92) using in-person performance-based tests (6-min walk test [6MWT], stair-climb test [SCT]) prior to and 3 months after TKA. Patients also completed the Western Ontario McMaster Universities Scales (WOMAC) pain and function subscales, and Pain Catastrophizing Scale, presurgery and 3- and 6-months postsurgery.

Results

Movement-evoked pain and function on performance tests significantly improved from pre- to post-TKA. Improved SCT function was associated with reduced SCT pain and catastrophizing. Similarly, reduced pain during the SCT was associated with reduced catastrophizing during the SCT. However, 6MWT function was not associated with 6MWT pain or catastrophizing; yet reduced pain during the 6MWT was associated with reduced catastrophizing during the 6MWT. Reduced movement-evoked pain during both performance tests was consistently associated with improved WOMAC function and pain, whereas improved function on performance tests was inconsistently associated with WOMAC function and pain. Notably, greater movement-evoked pain on both performance tests at 3-month post-TKA was associated with worse WOMAC function and pain at 6 months, whereas better function on performance tests at 3 months was associated with better WOMAC function, but not related to WOMAC pain at 6 months.

Discussion and Implications

Findings highlight the importance of situation-specific and in vivo assessments of pain and catastrophizing during physical activity.

A randomized, placebo-controlled, double-blinded mechanistic clinical trial using endotoxin to evaluate the relationship between insomnia, inflammation, and affective disturbance on pain in older adults: A protocol for the sleep and Healthy Aging Research for pain (SHARE-P) study

Chronic pain is prevalent in older adults. Treatment, especially with opioids, is often ineffective and poses considerable negative consequences in this population. To improve treatment, it is important to understand why older adults are at a heightened risk for developing chronic pain. Insomnia is a major modifiable risk factor for chronic pain that is ubiquitous among older adults. Insomnia can also lead to heightened systemic inflammation and affective disturbance, both of which may further exacerbate pain conditions in older adults. Endotoxin exposure can be used as an experimental model of systemic inflammation and affective disturbance. The current study aims to understand how insomnia status and endotoxin-induced changes in inflammation and affect (increased negative affect and decreased positive affect) may interact to impact pain facilitatory and inhibitory processes in older adults. Longitudinal data will also assess how pain processing, affective, and inflammatory responses to endotoxin may predict the development of pain and/or depressive symptoms. The current study is a randomized, double-blinded, placebo-controlled, mechanistic clinical trial in men and women, with and without insomnia, aged 50 years and older. Participants were randomized to either 0.8ng/kg endotoxin injection or saline placebo injection. Daily diaries were used to collect variables related to sleep, mood, and pain at two-week intervals during baseline and 3-, 6-, 9-, and 12-months post-injection. Primary outcomes during the experimental phase include conditioned pain modulation, temporal summation, and affective pain modulation ∼5.5 hours after injection. Primary outcomes for longitudinal assessments are self-reported pain intensity and depressive symptoms. The current study uses endotoxin as an experimental model for pain. In doing so, it aims to extend the current literature by: (1) including older adults, (2) investigating insomnia as a potential risk factor for chronic pain, (3) evaluating the role of endotoxin-induced affective disturbances on pain sensitivity, and (4) assessing sex differences in endotoxin-induced hyperalgesia.

Clinicaltrialsgov

NCT03256760.

Trial sponsor

NIH R01AG057750-01.

Microsecond Isomer at the N=20 Island of Shape Inversion Observed at FRIB

Excited-state spectroscopy from the first experiment at the Facility for Rare Isotope Beams (FRIB) is reported. A 24(2)-μs isomer was observed with the FRIB Decay Station initiator (FDSi) through a cascade of 224- and 401-keV γ rays in coincidence with ^{32}Na nuclei. This is the only known microsecond isomer (1  μs≤T_{1/2}<1  ms) in the region. This nucleus is at the heart of the N=20 island of shape inversion and is at the crossroads of the spherical shell-model, deformed shell-model, and ab initio theories. It can be represented as the coupling of a proton hole and neutron particle to ^{32}Mg, ^{32}Mg+π^{-1}+ν^{+1}. This odd-odd coupling and isomer formation provides a sensitive measure of the underlying shape degrees of freedom of ^{32}Mg, where the onset of spherical-to-deformed shape inversion begins with a low-lying deformed 2^{+} state at 885 keV and a low-lying shape-coexisting 0_{2}^{+} state at 1058 keV. We suggest two possible explanations for the 625-keV isomer in ^{32}Na: a 6^{-} spherical shape isomer that decays by E2 or a 0^{+} deformed spin isomer that decays by M2. The present results and calculations are most consistent with the latter, indicating that the low-lying states are dominated by deformation.

Brief Mindfulness-Based Cognitive Behavioral Therapy is Associated with Faster Recovery in Patients Undergoing Total Knee Arthroplasty: A Pilot Clinical Trial

OBJECTIVE

To assess whether brief mindfulness-based cognitive behavioral therapy (MBCBT) could enhance the benefits of total knee arthroplasty (TKA) in improving pain and pain-related disability. Specifically, to determine 1) whether patients who received MBCBT differed from matched controls who received treatment-as-usual with regard to postsurgical pain outcomes and 2) whether changes in pain catastrophizing, depression, or anxiety explained the potential effects of MBCBT on pain outcomes.

DESIGN

Pilot clinical trial.

SETTING

An academic teaching hospital serving a large urban and suburban catchment area surrounding the Boston, Massachusetts metropolitan region.

SUBJECTS

Sample of 44 patients undergoing TKA. Patients who completed a brief MBCBT intervention (n = 22) were compared with age-, race-, and sex-matched controls who received treatment-as-usual (n = 22).

METHODS

The MBCBT intervention included four 60-minute sessions delivered by a pain psychologist in person and via telephone during the perioperative period. Participants were assessed at baseline and at 6 weeks, 3 months, and 6 months after surgery.

RESULTS

Compared with matched controls, patients who received MBCBT had lower pain severity and pain interference at 6 weeks after surgery. Group differences in outcomes were mediated by changes in pain catastrophizing but not by changes in depression or anxiety. The MBCBT group had similar reductions in pain severity and interference as the control group did at 3 and 6 months after surgery.

CONCLUSIONS

This work offers evidence for a safe and flexibly delivered nonpharmacological treatment (MBCBT) to promote faster recovery from TKA and identifies change in pain catastrophizing as a mechanism by which this intervention could lead to enhanced pain-related outcomes.

Determining Profiles of Pain-Specific and General Emotion Regulation Skills and Their Relation to 12-Month Outcomes Among People With Chronic Pain

Difficulties with pain-specific emotion regulation (ER; eg, pain catastrophizing, pain acceptance) are associated with poor pain outcomes. Less is known about how general ER relates to pain outcomes, or the extent to which pain-specific and general ER interact. In a sample (N = 1,453) of adults with chronic pain, the current study used latent profile analysis to identify subgroups of people with distinct pain-specific and general ER profiles, and determined how subgroup membership at baseline related to pain severity, pain interference, depression and anxiety symptoms at 12-month follow-up. Four groups were identified: 1) general ER difficulties only (29.6%); 2) pain-specific and general ER difficulties (26.3%); 3) skillful pain-specific and general ER (24.6%); 4) pain-specific ER difficulties only (19.4%). Controlling for auto-correlation and demographic covariates, those with pain-specific and general ER difficulties had the worst outcomes in all domains. Membership to other groups did not differentiate between pain severity or interference outcomes; those skillful in pain-specific and general ER had the lowest depression and anxiety symptoms at 12 months. General ER difficulties are common among adults with chronic pain and raise relative risk when paired with pain-specific ER difficulties. Findings offer potential directions for individualizing pain psychology treatment. PERSPECTIVE: This article shows that people with chronic pain have different sets of strengths and difficulties when it comes to regulating emotions related and/or unrelated to the experience of pain itself. Understanding an individual's unique constellation of emotion regulation skills and difficulties might help personalize the psychological treatment of pain.

Depressive and Insomnia Symptoms Sequentially Mediate the Association Between Racism-Based Discrimination in Healthcare Settings and Clinical Pain Among Adults With Sickle Cell Disease

Racism-based discrimination in healthcare settings has been associated with clinical pain in adults living with sickle cell disease; however, no studies have examined depressive and insomnia symptoms as mechanisms that may drive this relationship. This secondary data analysis examined associations between depressive and insomnia symptoms, racism-based discrimination, and clinical pain. Seventy-one adults with sickle cell disease (70% female, Mage = 38.79) provided baseline reports of racism-based discrimination, depressive symptoms, insomnia symptoms, and pain (severity, interference, catastrophizing), and they completed daily diaries of pain severity and interference over 3 months. In a sequential mediation model, baseline depressive (1st) and insomnia symptoms (2nd) significantly mediated the association between racism-based discrimination and baseline pain interference, average daily diary pain severity, and average daily diary pain interference. Although the mediation model with baseline pain severity as the outcome was significant, the total and direct effects were not. Results indicate that discrimination in healthcare settings contributes to depression, which may act on pain through sleep disturbance. Findings support the need for systemic and structural changes to eliminate discrimination in healthcare settings and behavioral mood and sleep interventions to reduce the impact of discrimination on clinical pain. PERSPECTIVE: The relationship between discrimination in healthcare settings and pain in adults with sickle cell disease may be driven by depression and sleep disturbance, modifiable risk factors and potential treatment targets. Results suggest that systemic, structural, and institutional changes must be implemented to promote better patient care and health outcomes.

Nocturnal Delta Power is Associated With Lower Next-Day Pain But Not Pain Catastrophizing: Results From a Cohort of Female Participants With Temporomandibular Joint Pain

Existing data demonstrate reduced delta power during sleep in patients with depression and chronic pain. However, there has been little examination of the relationship between delta power and pain-reports, or pain-catastrophizing. We recruited female participants (n = 111) with insomnia and temporomandibular disorder, and measured nocturnal and daytime measures of pain and pain catastrophizing, and calculated relative nocturnal delta (0.5-4 Hz) power during sleep. We fit linear regression models, and further examined the moderating effect of depressive symptom severity. Lower relative delta power across the whole night was significantly associated with greater nocturnal pain (B = -20.276, P = .025, R² = 0.214). Lower relative delta power during the first-third of the night, was associated with greater nocturnal pain (B = -17.807, p = 0.019, R² = 0.217), next-day pain (B = 13.876, P = .039, R² = 0.195), and next-morning pain (B = -15.751, P = .022, R² = 0.198). Lower relative delta power during the final-third of the night was significantly associated with greater nocturnal (B = -17.602, P = .029, R² = 0.207) and next-morning pain (3^rd: B = -14.943, P = .042, R² = 0.187). Depressive symptom severity did not moderate these relationships. Delta power was not significantly associated with nocturnal or daytime pain catastrophizing. These findings demonstrate that greater relative delta power during sleep is associated with lower nocturnal and next-day pain in patients with temporomandibular disorder. This data may guide the use of sleep interventions in clinical pain populations, with the aim of improving pain outcomes. PERSPECTIVE: This article presents data demonstrating an association between increased nocturnal delta power and reduced next-day pain. These findings may help promote interventions which aim to increase nocturnal delta power in clinical pain populations, with the goal of improving pain outcomes.

Preliminary Evidence for the Sequentially Mediated Effect of Racism-Related Stress on Pain Sensitivity Through Sleep Disturbance and Corticolimbic Opioid Receptor Function

Sleep disturbance predicts worse pain outcomes. Because sleep disturbance inequitably impacts Black adults - with racism as the upstream cause - understanding how racism-related stress impacts pain through sleep might help minimize racialized pain inequities. This preliminary study examined sequential mediation of the effect of racism-related stress on experimental pain through sleep disturbance and corticolimbic μOR function in pain-free non-Hispanic Black (NHB) and White (NHW) adults. Participants completed questionnaires, actigraphy, positron emission tomography, and sensory testing. We reproduced findings showing greater sleep disturbance and pain sensitivity among NHB participants; greater sleep disturbance (r = .35) and lower pain tolerance (r=-.37) were significantly associated with greater racism-related stress. In a sequential mediation model, the total effect of racism-related stress on pain tolerance (β=-.38, P = .005) weakened after adding sleep disturbance and ventromedial prefrontal cortex (vmPFC) μOR binding potential (BPND) as mediators (β = -.18, P = .16). The indirect effect was statistically significant [point estimate = -.003, (-.007, -.0003). Findings showed a potential sequentially mediated effect of racism-related stress on pain sensitivity through sleep disturbance and vmPFC μOR BPND. As policy efforts are enacted to eliminate the upstream cause of systemic racism, these results cautiously suggest that sleep interventions within racism-based trauma informed therapy might help prevent downstream effects on pain. PERSPECTIVE: This preliminary study identified the effect of racism-related stress on pain through sleep disturbance and mu-opioid receptor binding potential in the ventromedial prefrontal cortex. Findings cautiously support the application of sleep interventions within racism-based trauma-informed therapy to prevent pain inequities as policy changes function to eliminate all levels of racism.

Crossing N=28 Toward the Neutron Drip Line: First Measurement of Half-Lives at FRIB

New half-lives for exotic isotopes approaching the neutron drip-line in the vicinity of N∼28 for Z=12-15 were measured at the Facility for Rare Isotope Beams (FRIB) with the FRIB decay station initiator. The first experimental results are compared to the latest quasiparticle random phase approximation and shell-model calculations. Overall, the measured half-lives are consistent with the available theoretical descriptions and suggest a well-developed region of deformation below ^{48}Ca in the N=28 isotones. The erosion of the Z=14 subshell closure in Si is experimentally confirmed at N=28, and a reduction in the ^{38}Mg half-life is observed as compared with its isotopic neighbors, which does not seem to be predicted well based on the decay energy and deformation trends. This highlights the need for both additional data in this very exotic region, and for more advanced theoretical efforts.

The Influence of Expectancies on Pain and Function Over Time After Total Knee Arthroplasty

OBJECTIVE

Expectancies have a well-documented influence on the experience of pain, responses to treatment, and postsurgical outcomes. In individuals with osteoarthritis, several studies have shown that expectations predict increased pain and disability after total knee replacement surgery. Despite the growing recognition of the importance of expectancies in clinical settings, few studies have examined the influence of expectancies throughout postsurgical recovery trajectories. The objective of the present study was to examine the role of presurgical expectancies on pain and function at 6-week, 6-month, and 1-year follow-ups after total knee arthroplasty.

DESIGN AND PARTICIPANTS

Data were collected from patients scheduled for total knee arthroplasty 1 week before surgery and then at 6 weeks, 6 months, and 1 year after surgery. Correlational and multivariable regression analyses examined the influence of expectancies on patients' perceptions of pain reduction and functional improvement at each time point. Analyses controlled for age, sex, body mass index, presurgical pain intensity and function, pain catastrophizing, anxiety, and depression.

RESULTS

Results revealed that expectancies significantly predicted pain reduction and functional improvement at 1-year follow-up. However, expectancies did not predict outcomes at the 6-week and 6-month follow-ups. Catastrophizing and depressive symptoms emerged as short-term predictors of postsurgical functional limitations at 6-week and 6-month follow-ups, respectively.

CONCLUSIONS

The results suggest that targeting high levels of catastrophizing and depressive symptoms could optimize short-term recovery after total knee arthroplasty. However, the results demonstrate that targeting presurgical negative expectancies could prevent prolonged recovery trajectories, characterized by pain and loss of function up to 1 year after total knee arthroplasty.

Trajectories and Individual Differences in Pain, Emotional Distress, and Prescription Opioid Misuse During the COVID-19 Pandemic: A One-Year Longitudinal Study

Recent studies suggest that the COVID-19 pandemic can serve as a unique psychosocial stressor that can negatively impact individuals with chronic pain. Using a large online sample in the U.S., the present study sought to investigate the impact of the pandemic on the trajectories of pain severity and interference, emotional distress (ie, anxiety and depressive symptoms), and opioid misuse behaviors across one year. Potential moderating effects of socio-demographic factors and individual differences in pain catastrophizing, pain acceptance, and sleep disturbance on outcome trajectories were also examined. Adults with chronic pain were surveyed three times across 1 year (April/May 2020 [N = 1,453]; June/July 2020 [N = 878], and May 2021 [N = 813]) via Amazon's Mechanical Turk online crowdsourcing platform. Mixed-effects growth models revealed that pain severity and interference, emotional distress, and opioid misuse behaviors did not significantly deteriorate across one year during the pandemic. None of the socio-demographic factors, pain catastrophizing, or sleep disturbance moderated outcome trajectories. However, individuals with higher pain acceptance reported greater improvement in pain severity (P< .008, 95% CI: -.0002, -.00004) and depressive symptoms (P< .001, 95% CI: -.001, -.0004) over time. Our findings suggest that the negative impact of the pandemic on pain, emotional distress, and opioid misuse behaviors is quite small overall. The outcome trajectories were also stable across different socio-demographic factors, as well as individual differences in pain catastrophizing and sleep disturbance. Nevertheless, interventions that target improvement of pain acceptance may help individuals with chronic pain be resilient during the pandemic. PERSPECTIVE: Individuals with chronic pain overall did not experience significant exacerbation of pain, emotional distress, and opioid misuse across one year during the COVID-19 pandemic. Individuals with higher pain acceptance showed greater improvement in pain severity and depressive symptoms over time during the pandemic.

The Longitudinal Relationship Between Emotion Regulation and Pain-Related Outcomes: Results From a Large, Online Prospective Study

People with chronic pain engage in various strategies, such as pain catastrophizing and pain acceptance, to regulate the difficult emotional aspects of living with pain. Engagement in these strategies is known to influence pain severity and pain interference. However, less research has examined the extent to which general emotion regulation, the ability to identify emotions and engage in strategies to alter emotions, relates to pain-related outcomes. The current study, a large (N = 1453) online prospective study of adults with chronic pain, employed theory-driven assessment of emotion regulation to determine the extent to which general difficulties with emotion regulation at baseline relate to pain severity and pain interference at three-month follow-up, above and beyond pain catastrophizing and pain acceptance. We conducted a series of path models, controlling for demographic covariates and baseline pain severity and pain interference. Pain catastrophizing and pain acceptance at baseline significantly predicted pain interference at three-month follow-up. However, when indices of general emotion regulation were entered into the model, the associations between pain catastrophizing and pain interference (B = .009, P = .153) were no longer statistically significant. Alexithymia emerged as a significant predictor of pain severity (B = .012, P = .032) and pain interference (B = .026, P < .001). These findings highlight the value of considering the role of general emotion regulation (particularly identifying and describing emotions), in addition to pain-specific experiences, in understanding risk for poor pain-related outcomes. PERSPECTIVE: In addition to pain catastrophizing and pain acceptance, difficulties regulating emotions in general (particularly elevated alexithymia) relates to pain outcomes three months later. These findings shed light on risk for poor pain outcomes and point to general emotion regulation as a potentially important target of chronic pain intervention.

Who are the placebo responders? A cross-sectional cohort study for psychological determinants

ABSTRACT

A number of studies have demonstrated substantial individual differences in placebo effects. We aimed to identify individual psychological factors that potentially predicted the magnitude of placebo hypoalgesia and individual responsiveness. The Research Domain Criteria framework and a classical conditioning with suggestions paradigm were adopted as experimental models to study placebo phenotypes in a cohort of 397 chronic pain participants with a primary diagnosis of temporomandibular disorder (TMD) and 397 healthy control (HC) participants. The magnitude of placebo hypoalgesia was operationalized as the average difference in pain ratings between the placebo and control conditions. The individual placebo responsiveness was identified as the status of placebo responders and nonresponders based on a permutation test. We observed significant placebo effects in both TMD and HC participants. A greater level of emotional distress was a significant predictor of smaller magnitude (slope b = -0.07) and slower extinction rate (slope b = 0.51) of placebo effects in both TMD and HC participants. Greater reward seeking was linked to greater postconditioning expectations (ie, reinforced expectations) in TMD (slope b = 0.16), but there was no such a prediction in HC participants. These findings highlight that negative valence systems might play a role in impairing placebo effects, with a larger impact in chronic pain participants than in healthy participants, suggesting that individuals reporting emotional distress and maladaptive cognitive appraisals of pain may benefit less from placebo effects.

Confronting Racism in All Forms of Pain Research: A Shared Commitment for Engagement, Diversity, and Dissemination

This third paper in the "Confronting Racism in All Forms of Pain Research" series discusses adopting an antiracism framework across all pain research disciplines and highlights the significant benefits of doing so. We build upon the previous call to action and the proposed reframing of study designs articulated in the other papers in the series and seek to confront and eradicate racism through a shared commitment to change current research practices. Specifically, we emphasize the systematic disadvantage created by racialization (ie, the Eurocentric social and political process of ascribing racialized identities to a relationship, social practice, or group) and discuss how engaging communities in partnership can increase the participation of racialized groups in research studies and enrich the knowledge gained. Alongside this critical work, we indicate why diversifying the research environment (ie, research teams, labs, departments, and culture) enriches our scientific discovery and promotes recruitment and retention of participants from racialized groups. Finally, we recommend changes in reporting and dissemination practices so that we do not stigmatize or reproduce oppressive forms of power for racialized groups. Although this shift may be challenging in some cases, the increase in equity, generalizability, and credibility of the data produced will expand our knowledge and reflect the pain experiences of all communities more accurately. PERSPECTIVE: In this third paper in our series, we advocate for a shared commitment toward an antiracism framework in pain research. We identify community partnerships, diversification of research environments, and changes to our dissemination practices as areas where oppressive forms of power can be reduced.

Temporal Association of Pain Catastrophizing and Pain Severity Across the Perioperative Period: A Cross-Lagged Panel Analysis After Total Knee Arthroplasty

OBJECTIVE

Although numerous studies show that preoperative pain catastrophizing is a risk factor for pain after total knee arthroplasty (TKA), little is known about the temporal course of the association between perioperative pain catastrophizing and pain severity. The present study investigated temporal changes and their dynamic associations between pain catastrophizing and pain severity before and after TKA.

DESIGN

A secondary data analysis of a larger observational parent study featuring prospective repeated measurement over 12 months.

SETTING

Dual-site academic hospital.

SUBJECTS

A total of 245 individuals who underwent TKA.

METHODS

Participants completed pain catastrophizing and pain severity questionnaires at baseline, 6 weeks, and 3, 6, and 12 months after TKA. Cross-lagged panel analysis was conducted with structural equation modeling including age, sex, race, baseline anxiety, and depressive symptoms as covariates.

RESULTS

Reduction in pain catastrophizing from baseline to 6 weeks after TKA was associated with lower pain severity at 3 months after TKA (standardized β = 0.14; SE = 0.07, P = 0.046), while reduction in pain severity at 6 weeks after TKA was not associated with pain catastrophizing at 3 months after TKA (P = 0.905). In the chronic postsurgical period (>3 months), pain catastrophizing at 6 months after TKA predicted pain severity at 12 months after TKA (β = 0.23, P = 0.009) with controlling for auto-correlation and covariates, but not vice versa.

CONCLUSIONS

We provide evidence that changes in pain catastrophizing from baseline to 6 weeks after TKA are associated with subsequent pain severity. Future studies are warranted to determine whether targeting pain catastrophizing during the perioperative period may improve clinical outcomes for individuals undergoing TKA.

Racial disparities in sleep-related cardiac function in young, healthy adults: Implications for cardiovascular-related health

STUDY OBJECTIVES

Considerable evidence shows that individuals from marginalized racial/ethnic groups in the US experience greater rates of sleep disturbance and cardiovascular complications. Because sleep is a modifiable factor that is critically involved in cardiovascular health, improved understanding of the association between sleep and cardiovascular health during early adulthood can prevent cardiovascular disparities. This study examined racial/ethnic differences in cardiovascular function during sleep using heart-rate and heart-rate-variability analyses.

METHODS

Participants in this laboratory-based sleep study included healthy, "good sleepers" who were in early adulthood and resided in the US at the time of participation [14 non-Hispanic Black (NHB; age=30.9(6.6), 57% female), 12 Asian (Asian, age=26.0(5.2), 42% female), and 24 non-Hispanic white (NHW; age=24.6(5.8), 79% female)].

RESULTS

After adjusting for demographic factors and an apnea-hypopnea index, we found significantly higher heart rate within NREM Stage 2 (N2) (b=-22.6, p=.04) and REM sleep (b=-25.8, p=.048) and lower heart rate variability during N2 sleep (b=-22.6, p=.04) among NHB individuals compared to NHW individuals. Further, NHB and Asian participants demonstrated significantly lower percent of time in slow wave sleep (SWS) compared to NHW participants (NHB: b=-22.6, p=.04; Asian: b=-22.6, p=.04). Individuals' percent of time in SWS significantly mediated differences in heart rate during N2 [indirect=0.94, 95% CI (0.03, 2.68)] and REM sleep [indirect=1.02, 95% CI (0.04, 3.04)].

CONCLUSIONS

Our results showed disparities in sleep-related cardiovascular function in early adulthood that are mediated by SWS. These data suggest targeting sleep health in early adulthood might help reduce cardiovascular disease burden on individuals from marginalized groups.

Within-subject, double-blinded, randomized, and placebo-controlled evaluation of the combined effects of the cannabinoid dronabinol and the opioid hydromorphone in a human laboratory pain model

This Phase II study evaluated analgesia, abuse liability, and cognitive performance of hydromorphone and oral delta-9-tetrahydrocannabinol (THC; dronabinol) using a within-subject, double-blind, randomized, placebo-controlled, human laboratory trial. Healthy adults (N = 29) with no history of drug use disorder received combinations of placebo, hydromorphone (4 mg; oral), and dronabinol (2.5 mg, 5.0 mg, 10 mg; oral). Primary outcomes were quantitative sensory testing (QST) measures of acute (thermal, pressure pain; thermal, punctate probe temporal summation; cold pressor; conditioned pain modulation) and chronic pain (capsaicin 10% topical cream with thermal rekindling), measures of drug abuse liability, cognitive functioning, and adverse events. Subgroup analyses were conducted within opioid-responders (endorsed >20 on a Drug Effect visual analog scale during the hydromorphone-only condition) and nonresponders. A consistent dose-effect relationship of dronabinol on hydromorphone across all measures was not observed. Analgesia only improved in the hydromorphone + dronabinol 2.5 mg condition. Hydromorphone + dronabinol 2.5 mg showed the lowest and hydromorphone+dronabinol 5 mg showed the highest risk for abuse. Hydromorphone+dronabinol 10 mg produced a high rate of dysphoric effects, and hydromorphone+dronabinol 5 mg and hydromorphone + dronabinol 10 mg produced AEs. Subgroup analyses showed subjective effects and abuse risk was increased among opioid responders and largely absent among nonresponders. Overall, only hydromorphone+dronabinol 2.5 mg modestly enhanced hydromorphone-based analgesia and hydromorphone + dronabinol 5 mg and 10 mg increased risk for abuse and AEs. These data can help inform opioid-sparing efforts in clinical pain populations. Demonstration that potential opioid effects varied as a function of participant opioid sensitivity (e.g., responder status) is a novel finding that warrants additional research.

The Early Impact of COVID-19 on Chronic Pain: A Cross-Sectional Investigation of a Large Online Sample of Individuals with Chronic Pain in the United States, April to May, 2020

OBJECTIVE

Individuals with chronic pain are uniquely challenged by the COVID-19 pandemic, as increased stress may exacerbate chronic pain, and there are new barriers to receiving chronic pain treatment. In light of this, using a large online sample in the United States, we examined 1) the early impact of COVID-19 on pain severity, pain interference, and chronic pain management; and 2) variables associated with perceived changes in pain severity and pain interference.

DESIGN

A cross-sectional study.

METHODS

Online survey data for 1,453 adults with chronic pain were collected via Amazon's Mechanical Turk platform.

RESULTS

Although a large proportion of participants reported no perceived changes in their pain severity and pain interference since the outbreak, approximately 25-30% of individuals reported exacerbation in these domains. Individuals identifying as Black and of non-Hispanic origin, who experienced greater disruptions in their mood and sleep quality, were more likely to report worsened pain interference. The majority of participants reported engaging in self-management strategies as usual. However, most appointments for chronic pain treatment were either postponed or canceled, with no future session scheduled. Furthermore, a notable proportion of participants had concerns about or difficulty accessing prescription opioids due to COVID-19.

CONCLUSIONS

We may expect to see a long-term exacerbation of chronic pain and related interference in functioning and chronic pain management among individuals most impacted by the pandemic. These individuals may benefit from remotely delivered intervention to effectively mitigate COVID-19-related exacerbations in chronic pain and interruptions in face-to-face treatment.

Clinical Factors Associated With Chronic Pain in Communicative Adults With Cerebral Palsy: A Cross-Sectional Study

Chronic pain is prevalent in adults with cerebral palsy. We aimed to explore associations between chronic pain and somatosensory, motor, cognitive, etiologic, and environmental factors in adults with cerebral palsy. This cross-sectional study enrolled 17 adult participants with cerebral palsy (mean age 31 years; 8 female; Gross Motor Functional Classification Status levels I-V) able to self-report and 10 neurotypical adult volunteers (mean age 34 years; 9 female). Participants reported pain characteristics, demographics, and affective factors. Physical examination included somatosensory and motor evaluation. Between-group comparisons used a ranksum test, and correlation analyses estimated effect size in terms of shared variance (ρ²). Individuals with cerebral palsy reported greater pain intensity, neuropathic qualities, and nociceptive qualities than control participants. Higher pain intensity was associated with female gender (ρ² = 16%), anxiety/depression symptoms (ρ² = 10%), and lower household income (ρ² = 19%). It was also associated with better communicative ability (ρ² = 21%), spinothalamic (sharp/temperature) sensory abnormalities (ρ² = 33%), and a greater degree of prematurity (ρ² = 17%). This study highlights similarity of chronic pain associations in people with cerebral palsy with patterns seen in other populations with chronic pain. Spinothalamic sensory abnormalities suggest central pain mechanisms.

Experimental sleep disruption attenuates morphine analgesia: findings from a randomized trial and implications for the opioid abuse epidemic

Preclinical studies demonstrate that sleep disruption diminishes morphine analgesia and modulates reward processing. We sought to translate these preclinical findings to humans by examining whether sleep disruption alters morphine's analgesic and hedonic properties. We randomized 100 healthy adults to receive morphine versus placebo after two nights of undisturbed sleep (US) and two nights of forced awakening (FA) sleep disruption. Sleep conditions were counterbalanced, separated by a two-week washout. The morning after both sleep conditions, we tested cold pressor pain tolerance before and 40-min after double-blind injection of .08 mg/kg morphine or placebo. The primary outcome was the analgesia index, calculated as the change in cold pressor hand withdrawal latency (HWL) before and after drug injection. Secondary outcomes were ratings of feeling "high," drug "liking," and negative drug effects. We found a significant sleep condition by drug interaction on the analgesia index (95% CI - 0.57, - 0.001). After US, subjects receiving morphine demonstrated significantly longer HWL compared to placebo (95% CI 0.23, 0.65), but not after FA (95% CI - 0.05, 0.38). Morphine analgesia was diminished threefold under FA, relative to US. After FA, females (95% CI - 0.88, - 0.05), but not males (95% CI - 0.23, 0.72), reported decreased subjective "high" effects compared to US. After FA, females (95% CI 0.05, 0.27), but not males (95% CI - 0.10, 0.11), administered morphine reported increased negative drug effects compared to US. These data demonstrate that sleep disruption attenuates morphine analgesia in humans and suggest that sleep disturbed males may be at greatest risk for problematic opioid use.

A Preliminary Investigation of the Underlying Mechanism Associating Daily Sleep Continuity Disturbance and Prescription Opioid Use Among Individuals With Sickle Cell Disease

BACKGROUND

There are emerging data indicating that sleep disturbance may be linked with an increase in opioid use. The majority of sickle cell disease (SCD) patients experience sleep disturbances, which can elevate pain severity and pain catastrophizing, both of which are important predictors of opioid consumption.

PURPOSE

We conducted a preliminary investigation on the association between previous night sleep disturbance and short-acting opioid use, as well as the potential mediating roles of pain severity and pain catastrophizing. Because sex is associated with sleep disturbance, pain-related experiences, and opioid use, we also explored the potential moderating role of sex.

METHODS

Participants were 45 SCD patients who were prescribed opioids. For 3 months, sleep diaries were collected immediately upon participants' awakening. Daily pain severity, pain catastrophizing, and prescription opioid use measures were collected before bedtime.

RESULTS

Multilevel structural equation modeling revealed that wake time after sleep onset (WASO) during the previous night (Time 1) predicted greater short-acting opioid use during the next day (Time 2). Pain severity and pain catastrophizing measured during the next day (Time 2) also mediated the association between the two. Sex moderation analysis showed that the positive association between WASO and pain severity was largely driven by women.

CONCLUSION

These findings provide some preliminary evidence as to the mechanism linking sleep continuity disturbance and opioid requirement in SCD patients. Future studies should replicate and extend these findings with clearer temporal information and employing more refined measures of sleep continuity and prescription opioid use in a larger sample.

Experimenter- and Infrared Thermography-Derived Measures of Capsaicin-Induced Neurogenic Flare Among Non-Hispanic White and Black Adults

OBJECTIVE

Capsaicin is a widely utilized experimental pain stimulus; however, few studies have reported on ethnic differences in pain responses to capsaicin. The present study used infrared thermography to 1) measure differences in capsaicin-induced neurogenic flare between non-Hispanic black (NHB) and non-Hispanic white (NHW) adults and 2) determine the association between neurogenic flare and secondary hyperalgesia.

METHODS

Fifty-four participants (NHB N = 28) underwent heat/capsaicin sensitization model procedures. Neurogenic flare was examined using experimenter (i.e., subjective) and thermography (i.e., objective) measurements. A typically nonpainful mechanical punctate probe was used to measure secondary hyperalgesia.

RESULTS

Ethnic groups did not significantly differ in age, sex, marital status, or personal income. Although experimenters rated a significantly wider area of capsaicin-related neurogenic flare among NHW compared with NHB participants (F1, 52 = 8.33, P = 0.006), thermography results showed no differences between groups in neurogenic flares (F1, 52 = 0.01, P = 0.93). Further, although NHB individuals reported greater average pain during the capsaicin procedures compared with NHW individuals (NHB = 58.57 [3.67], NHW = 46.46 [3.81]; F2, 51 = 5.19, P = 0.03), the groups did not differ in secondary hyperalgesia (F2, 51 = 0.03, P = 0.86), and ethnicity did not moderate the association between neurogenic flare and secondary hyperalgesia (F3, 50 = 0.24, P = 0.87).

CONCLUSIONS

Findings cautiously support the use of infrared thermography over subjective experimenter report when measuring neurogenic inflammation in diverse samples. However, infrared thermography should not be used as a diagnostic tool for pain, given the lack of association between these factors. Future research is warranted to replicate these findings in a larger and more diverse sample to determine accurate neurogenic inflammation measures across other ethnic minority populations.

Shape Coexistence at Zero Spin in ^{64}Ni Driven by the Monopole Tensor Interaction

The low-spin structure of the semimagic ^{64}Ni nucleus has been considerably expanded: combining four experiments, several 0^{+} and 2^{+} excited states were identified below 4.5 MeV, and their properties established. The Monte Carlo shell model accounts for the results and unveils an unexpectedly complex landscape of coexisting shapes: a prolate 0^{+} excitation is located at a surprisingly high energy (3463 keV), with a collective 2^{+} state 286 keV above it, the first such observation in Ni isotopes. The evolution in excitation energy of the prolate minimum across the neutron N=40 subshell gap highlights the impact of the monopole interaction and its variation in strength with N.

Placebo hypoalgesia: racial differences

No large-cohort studies that examine potential racial effects on placebo hypoalgesic effects exist. To fill this void, we studied placebo effects in healthy and chronic pain participants self-identified as either African American/black (AA/black) or white. We enrolled 372 study participants, 186 with a diagnosis of temporomandibular disorder (TMD) and 186 race-, sex-, and age-matched healthy participants to participate in a placebo experiment. Using a well-established paradigm of classical conditioning with verbal suggestions, each individual pain sensitivity was measured to calibrate the temperatures for high- and low-pain stimuli in the conditioning protocol. These 2 temperatures were then paired with a red and green screen, respectively, and participants were told that the analgesic intervention would activate during the green screens to reduce pain. Participants then rated the painfulness of each stimulus on a visual analog scale ranging from 0 to 100. Racial influences were tested on conditioning strength, reinforced expectations, and placebo hypoalgesia. We found that white participants reported greater conditioning effects, reinforced relief expectations, and placebo effects when compared with their AA/black counterparts. Racial effects on placebo were observed in TMD, although negligible, short-lasting, and mediated by conditioning strength. Secondary analyses on the effect of experimenter-participant race and sex concordance indicated that same experimenter-participant race induced greater placebo hypoalgesia in TMDs while different sex induced greater placebo hypoalgesia in healthy participants. This is the first and largest study to analyze racial effects on placebo hypoalgesia and has implications for both clinical research and treatment outcomes.

Identification of the New Isotope ^{244}Md

In an experiment performed at Lawrence Berkeley National Laboratory's 88-inch cyclotron, the isotope ^{244}Md was produced in the ^{209}Bi(^{40}Ar,5n) reaction. Decay properties of ^{244}Md were measured at the focal plane of the Berkeley Gas-filled Separator, and the mass number assignment of A=244 was confirmed with the apparatus for the identification of nuclide A. The isotope ^{244}Md is reported to have one, possibly two, α-decaying states with α energies of 8.66(2) and 8.31(2) MeV and half-lives of 0.4_{-0.1}^{+0.4} and ∼6  s, respectively. Additionally, first evidence of the α decay of ^{236}Bk was observed and is reported.

Evaluating the co-use of opioids and cannabis for pain among current users using hypothetical purchase tasks

BACKGROUND

Cannabinoids may potentiate opioid analgesia and therefore could be used to reduce reliance on opioids for analgesia.

AIMS

The current study evaluated whether the concurrent availability of cannabis influences opioid consumption using a behavioral economic demand framework.

METHODS

An online survey assessed cannabis and opioid use frequency and dependence measures, pain severity, and demand for both cannabis and opioids alone and when concurrently available using hypothetical purchase tasks. Adults reporting current use of opioids for pain management and past 30-day cannabis exposure (N=155) completed two hypothetical purchase tasks in which only grams of cannabis or units of participants' index opioids were available for purchase, and two hypothetical tasks in which both were concurrently available and the price of one drug increased whereas the other was kept constant. Paired-sample t-tests compared the demand of each drug alone with when it was available concurrently with an alternative.

RESULTS

Demand intensity was significantly reduced and demand elasticity was significantly increased for both cannabis and opioids when the alternate commodity was available, although the reductions in cannabis consumption were more pronounced than they were for opioid consumption in the presence of the alternate commodity.

CONCLUSIONS

These data provide behavioral economic evidence that cannabis access may modestly reduce demand for opioids in persons who have pain. Additional clinical studies that evaluate the analgesic effects of cannabis and cannabis-opioid effects on pain are warranted.

Ethnic Differences in Experimental Pain Responses Following a Paired Verbal Suggestion With Saline Infusion: A Quasiexperimental Study

BACKGROUND

Ethnic differences in placebo and nocebo responses are an important, yet underresearched, patient factor that might contribute to treatment disparities.

PURPOSE

The purpose of this study was to examine ethnic differences in pain trajectories following a verbal suggestion paired with a masked, inert substance (i.e., saline).

METHODS

Using a quasiexperimental design, we examined differences between 21 non-Hispanic Black (NHB) participants and 20 non-Hispanic White (NHW) participants in capsaicin-related pain rating trajectories following a nondirectional verbal suggestion + saline infusion. All participants were told that the substance would "either increase pain sensation, decrease it, or leave it unchanged." A spline mixed model was used to quantify the interaction of ethnicity and time on ratings.

RESULTS

There was a significant Ethnicity × Time interaction effect (β = -0.28, p = .002); NHB individuals reported significantly greater increases in pain following, but not before, the verbal suggestion + saline infusion. Sensitivity analyses showed no change in primary results based on differences in education level, general pain sensitivity, or condition order.

CONCLUSIONS

The present results showed ethnic differences in pain response trajectories following a verbal suggestion + saline infusion and suggest that future research rigorously examining possible ethnic differences in placebo/nocebo responses is warranted.

Linking Nonrestorative Sleep and Activity Interference Through Pain Catastrophizing and Pain Severity: An Intraday Process Model Among Individuals With Fibromyalgia

Nonrestorative sleep is a key diagnostic feature of the musculoskeletal pain disorder fibromyalgia and is robustly associated with poor physical functioning, including activity interference. However, the mechanisms through which nonrestorative sleep elicits activity interference among individuals with fibromyalgia at the within-person level remain unclear. The present study tested the following 3-path mediation model, using data gathered from a 21-day electronic daily diary in 220 individuals with fibromyalgia: previous night nonrestorative sleep → morning pain catastrophizing → afternoon pain severity → end-of-day activity interference. Results of multilevel structural equation modeling supported the 3-path mediation model. Previous night's nonrestorative sleep and morning pain catastrophizing were also directly related to end-of-day activity interference. Previous night nonrestorative sleep did not significantly predict afternoon pain severity while controlling for the effect of morning pain catastrophizing. Greater nonrestorative sleep during the previous night and a higher level of morning pain catastrophizing appear to serve as risk factors for experiencing greater daily pain and activity interference later in the day. These findings point to the potential utility of targeted interventions that improve both sleep quality and pain catastrophizing to help individuals with chronic pain engage in important daily activities despite experiencing pain. PERSPECTIVE: This study provides a better understanding of how nonrestorative sleep is associated with daily activity interference among individuals with fibromyalgia. An intervention that targets attenuating nonrestorative sleep and pain catastrophizing may help improve daily physical functioning of this population.

Sex Differences in Interleukin-6 Responses Over Time Following Laboratory Pain Testing Among Patients With Knee Osteoarthritis

Epidemiological studies suggest that women are not only at a higher risk for developing knee osteoarthritis (KOA), but also report greater symptom severity compared to men. One potential underlying mechanism of these sex differences may be exaggerated inflammatory responses to pain among women compared to men. The present study examined sex differences in interleukin-6 (IL-6) response over time following experimental pain testing. We hypothesized that women, when compared to men, would show greater IL-6 reactivity when exposed to acute pain in a human laboratory setting. Eighty-four participants (36 men and 48 women) with KOA scheduled for total knee arthroplasty underwent a quantitative sensory testing (QST) battery. A total of seven IL-6 measurements were taken, twice at baseline, once immediately after QST, and every 30 minutes up to 2 hours after QST. Consistent with our hypothesis, women, when compared to men, showed accelerated increases in IL-6 levels following laboratory-evoked pain, even after controlling for body mass index, marital status, clinical pain, evoked pain sensitivity, and situational pain catastrophizing. Given that KOA is a chronic condition, and individuals with KOA frequently experience pain, these sex differences in IL-6 reactivity may contribute to the maintenance and/or exacerbation of KOA symptoms. PERSPECTIVES: The present study demonstrates that women, when compared to men, exhibit greater IL-6 reactivity after exposure to laboratory-evoked pain. Such sex differences may explain the mechanisms underlying women's higher chronic pain risk and pain perception, as well as provide further insight in developing personalized pain interventions.

Dynamic Brain Activity Following Auricular Point Acupressure in Chemotherapy-Induced Neuropathy: A Pilot Longitudinal Functional Magnetic Resonance Imaging Study

Background

The objective of this study was to investigate the dynamic brain activity following auricular point acupressure (APA) in chemotherapy-induced neuropathy (CIN).

Methods

Participants received 4 weeks of APA in an open-pilot trial with repeated observation. Along with the clinical self-reported CIN outcomes, objective outcomes were measured over the course of the treatment by physiological changes in pain sensory thresholds from quantitative sensory testing (QST) and repeated functional magnetic resonance imaging scans.

Results

After 4 weeks of APA, participants had reported clinically significant improvements (ie, ≥30%) in a reduction of CIN symptoms (including pain, numbness, tingling, and stiffness) in lower extremity stiffness (32%), reduced foot sensitivity (13%), and higher pain threshold (13%). Across the 11 intrinsic brain networks examined, there was a trend toward significance of the connectivity of the basal ganglia network (BGN) to the salience network (SAL), which was decreased pre-APA versus immediate-APA (effect size [ES] = 1.04, P = .07). The BGN also demonstrated decreased connectivity with the language network pre-APA versus delayed imaging post-APA (ES = −0.92, P = .07). Furthermore, there was increased executive control network (ECN) and SAL within-network connectivity comparing pre-APA to delayed imaging post-APA, trending toward significance (ES = 0.41, P = .09 and ES = 0.17, P = .09, respectively).

Conclusion

The changes in connectivity and activity within or between the ECN, SAL, and BGN from pre- to post-APA suggest ongoing alterations in brain functional connectivity following APA, particularly in the insula, anterior cingulate, and dorsolateral prefrontal cortices, which play significant roles in pain, memory, and cognitive function.

Cannabinoid effects on responses to quantitative sensory testing among individuals with and without clinical pain: a systematic review

There has been an explosion of interest in the utility of cannabinoids as potential analgesics. This systematic review critically synthesizes the evidence for cannabinoid analgesic effects on quantitative sensory testing outcomes in both healthy adults and patients with chronic noncancer pain. Our systematic review protocol is preregistered on PROSPERO (CRD42018117367). An electronic search was made in PsycINFO, Cochrane, Google Scholar, Embase, and Pubmed of all literature published until August 2018. Of the 1217 studies found from the search, a total 39 placebo-controlled studies that met the eligibility criteria were synthesized for this study. Because of substantial heterogeneity of study designs, populations, cannabinoid compounds, and quantitative sensory testing outcomes, meta-analysis was not conducted. More consistent evidence of cannabinoid analgesia was observed for inhaled cannabis than synthetic cannabinoids. Analgesic effects were most commonly observed in tests of cold pain sensitivity, and hyperalgesic effects were most commonly observed in tests of electrical stimulation. Patterns of findings from studies with healthy subjects did not substantively differ from those with chronic noncancer pain. However, these observations are qualified by the high degree of inconsistency across studies and methodological heterogeneity. We offer recommendations for future studies to improve study rigor and reproducibility.

Missed targets, reaction times, and arousal are related to trait anxiety and attention to pain during an experimental vigilance task with a painful target

Although hypervigilance may play a role in some clinical pain syndromes, experimental vigilance toward painful stimuli has been studied infrequently. We evaluated vigilance toward pain by using a continuous performance task (CPT), in which subjects responded to moderately intense painful target stimuli, occurring in a train of mildly painful nontargets. We assessed nondetected targets (misses), reaction times (RTs), and psychological activation (tense arousal). During time on task in CPTs of other sensory modalities, there is an increase in misses and RTs (vigilance decrement). We hypothesized that our CPT would influence vigilance performance related to pain, anxiety, and limitation of attentional resources. The results showed a decrement in vigilance over time as misses increased, although RTs were unchanged. While mind-wandering did not influence vigilance performance, intrinsic attention to pain drove both hit RTs and number of misses. This resulted in pain-focused subjects performing worse on the CPT pain task with slower RTs and more misses per block. During the CPT, the change in stimulus salience was related to the change in pain intensity, while pain unpleasantness correlated with tense arousal. CPT performance during experimental vigilance to pain and psychological activation were related to trait anxiety, as measured by the Spielberger State-Trait Anxiety Inventory and neuroticism, as measured by the NEO five factor inventory. Trait anxiety and neuroticism may play important roles in an individual's predisposition to dwell on pain and interpret pain as threatening.NEW & NOTEWORTHY Subjects detected moderately painful target stimuli in a train of mildly painful nontarget stimuli, which resulted in vigilance performance metrics including missed targets, reaction times, and psychological activation. These performance metrics were related to intrinsic attention to pain and trait anxiety. Subjects with high trait anxiety and neuroticism scores, with a predisposition to attend to pain, had greater tense arousal and poorer vigilance performance, which may be important psychological aspects of vigilance to pain.

Biomarkers in Temporomandibular Disorder and Trigeminal Neuralgia: A Conceptual Framework for Understanding Chronic Pain

In this review, we will explore the use of biomarkers in chronic pain, using the examples of two prototypical facial pain conditions: trigeminal neuralgia and temporomandibular disorder. We will discuss the main categories of biomarkers and identify various genetic/genomic, molecular, neuroradiological, and psychophysical biomarkers in both facial pain conditions, using them to compare and contrast features of neuropathic, nonneuropathic, and mixed pain. By using two distinct model facial pain conditions to explore pain biomarkers, we aim to familiarize readers with different types of biomarkers currently being studied in chronic pain and explore how these biomarkers may be used to develop new precision medicine approaches to pain diagnosis, prognosis, and management.

Individuals with Chronic Pain Who Misuse Prescription Opioids Report Sex-Based Differences in Pain and Opioid Withdrawal

Objective Individuals with chronic pain who misuse prescription opioids are at high risk for developing opioid use disorder and/or succumbing to opioid overdose. The current study conducted a survey to evaluate sex-based differences in pain catastrophizing, opioid withdrawal, and current pain in persons with co-occurring chronic pain and opioid misuse. We hypothesized that women with chronic pain who misused prescription opioids would self-report higher pain ratings compared with men and that the relationship between pain catastrophizing and self-reported current pain would be moderated by symptoms of opioid withdrawal in women only. Design Survey assessment of the relationship between pain and opioid misuse. Setting Online via Amazon Mechanical Turk. Participants Persons with ongoing chronic pain who also misused prescription opioids on one or more days in the last 30 days were eligible (N = 181). Methods Participants completed demographic and standardized assessments including the Brief Pain Inventory (BPI), Pain Catastrophizing Scale (PCS), and Subjective Opiate Withdrawal Scale (SOWS). Results Women reported higher levels of current (P < 0.001), average (P < 0.001), and worst (P = .002) pain in the last 24 hours compared with men. Women also endorsed higher scores on the PCS (P = 0.006) and marginally higher past-30-day SOWS ratings (P = 0.068) compared with men. SOWS ratings moderated the relationship between PCS and BPI Worst Pain in women (ΔR2 < 0.127, ΔF(1, 78) = 12.39, P = 0.001), but not in men (ΔR2 < 0.000, ΔF(1, 98) = 0.003, P = 0.954). Conclusions These data suggest a strong relationship between opioid withdrawal, pain catastrophizing, and the experience of pain in women with chronic pain who misuse opioids.

Is the Structure of ^{42}Si Understood?

A more detailed test of the implementation of nuclear forces that drive shell evolution in the pivotal nucleus ^{42}Si-going beyond earlier comparisons of excited-state energies-is important. The two leading shell-model effective interactions, SDPF-MU and SDPF-U-Si, both of which reproduce the low-lying ^{42}Si(2_{1}^{+}) energy, but whose predictions for other observables differ significantly, are interrogated by the population of states in neutron-rich ^{42}Si with a one-proton removal reaction from ^{43}P projectiles at 81  MeV/nucleon. The measured cross sections to the individual ^{42}Si final states are compared to calculations that combine eikonal reaction dynamics with these shell-model nuclear structure overlaps. The differences in the two shell-model descriptions are examined and linked to predicted low-lying excited 0^{+} states and shape coexistence. Based on the present data, which are in better agreement with the SDPF-MU calculations, the state observed at 2150(13) keV in ^{42}Si is proposed to be the (0_{2}^{+}) level.

Sex differences in negative affect and postoperative pain in patients undergoing total knee arthroplasty

Background

Knee osteoarthritis (OA) is among the most common and disabling persistent pain conditions, with increasing prevalence in the developed world, and affects women to a greater degree than men. In the USA, the growth of knee OA has been paralleled by an increase in rates of total knee arthroplasty (TKA), a surgical treatment option for late-stage knee OA. While TKA outcomes are generally good, postoperative trajectories of pain vary widely, with some patients reporting a complete absence of pain, but with a significant minority reporting worsening pain. Biopsychosocial factors, including anxiety and depression, are known to contribute importantly to the experience of joint pain, with women reporting a higher degree of negative affective symptoms.

Methods

This study investigated sex differences in TKA outcomes in age-matched groups of men and women at two academic medical centers. Pain and physical function were assessed in 100 patients (50 men and 50 women) during the perioperative period (preoperative visit—6 weeks postsurgical). The association of preoperative negative affect (anxiety and depression scores) to postoperative pain and function was evaluated, with specific attention to sex differences in this relationship.

Results

Overall, women reported more baseline pain-related physical dysfunction (although not higher baseline pain scores), as well as higher acute postoperative pain scores during the 2 weeks following TKA than their male counterparts. By 6 weeks postoperatively, sex differences in reported pain were no longer evident. Interestingly, although women reported higher preoperative levels of emotional distress than men, preoperative anxiety and depression scores were better predictors of severe postoperative pain among men than women, throughout the postoperative test period.

Conclusions

This study underlines the importance of considering sex and psychosocial factors, as well as their interaction, in understanding postsurgical pain trajectories.

Quantitative sensory testing in children with sickle cell disease: additional insights and future possibilities

Quantitative sensory testing (QST) is used in a variety of pain disorders to characterize pain and predict prognosis and response to specific therapies. In this study, we aimed to confirm results in the literature documenting altered QST thresholds in sickle cell disease (SCD) and assess the test-retest reliability of results over time. Fifty-seven SCD and 60 control subjects aged 8-20 years underwent heat and cold detection and pain threshold testing using a Medoc TSAII. Participants were tested at baseline and 3 months; SCD subjects were additionally tested at 6 months. An important facet of our study was the development and use of a novel QST modelling approach, allowing us to model all data together across modalities. We have not demonstrated significant differences in thermal thresholds between subjects with SCD and controls. Thermal thresholds were consistent over a 3- to 6-month period. Subjects on whom hydroxycarbamide (HC) was initiated shortly before or after baseline testing (new HC users) exhibited progressive decreases in thermal sensitivity from baseline to 6 months, suggesting that thermal testing may be sensitive to effective therapy to prevent vasoocclusive pain. These findings inform the use of QST as an endpoint in the evaluation of preventative pain therapies.

First Spectroscopy of the Near Drip-line Nucleus ^{40}Mg

One of the most exotic light neutron-rich nuclei currently accessible for experimental study is ^{40}Mg, which lies at the intersection of the nucleon magic number N=28 and the neutron drip line. Low-lying excited states of ^{40}Mg have been studied for the first time following a one-proton removal reaction from ^{41}Al, performed at the Radioactive Isotope Beam Factory of RIKEN Nishina Center with the DALI2 γ-ray array and the ZeroDegree spectrometer. Two γ-ray transitions were observed, suggesting an excitation spectrum that shows unexpected properties as compared to both the systematics along the Z=12, N≥20  Mg isotopes and available state-of-the-art theoretical model predictions. A possible explanation for the observed structure involves weak-binding effects in the low-lying excitation spectrum.