Pain tolerance as a 'barrier' to nonsuicidal self-injury: A longitudinal study

Theoretical perspectives underscore that low pain tolerance may be a relevant 'barrier' to non-suicidal self-injury (NSSI). However, there is limited longitudinal work on the link between pain tolerance and NSSI, which is needed to assess if pain tolerance precedes NSSI engagement, and/or if NSSI precedes altered pain tolerance. Further, assessing both NSSI frequency and versatility (or number of NSSI methods), in addition to engagement, can provide a more nuanced understanding of the influence of pain on NSSI severity. In the present study, 1125 undergraduate students at a large university (72 % female, Mage = 17.96) reported on their NSSI frequency, NSSI versatility, and perceived pain tolerance. Four individual regressions were run to examine the potential bidirectional nature of the association between NSSI frequency and pain tolerance, and NSSI versatility and pain tolerance. Pain tolerance predicted both NSSI frequency and versatility over time. Neither NSSI frequency nor versatility predicted pain tolerance. Results suggest that high pain tolerance may be a risk factor for severe NSSI engagement.

Investigating mortality salience as a potential causal influence and moderator of responses to laboratory pain

Background

Because pain can have profound ramifications for quality of life and daily functioning, understanding nuances in the interplay of psychosocial experiences with pain perception is vital for effective pain management. In separate lines of research, pain resilience and mortality salience have emerged as potentially important psychological correlates of reduced pain severity and increased tolerance of pain. However, to date, there has been a paucity of research examining potentially interactive effects of these factors on pain perception. To address this gap, the present experiment investigated mortality salience as a causal influence on tolerance of laboratory pain and a moderator of associations between pain resilience and pain tolerance within a Chinese sample.

Methods

Participants were healthy young Chinese adults (86 women, 84 men) who first completed a brief initial cold pressor test (CPT) followed by measures of demographics and pain resilience. Subsequently, participants randomly assigned to a mortality salience (MS) condition completed two open-ended essay questions in which they wrote about their death as well as a death anxiety scale while those randomly assigned to a control condition completed analogous tasks about watching television. Finally, all participants engaged in a delay task and a second CPT designed to measure post-manipulation pain tolerance and subjective pain intensity levels.

Results

MS condition cohorts showed greater pain tolerance than controls on the post-manipulation CPT, though pain intensity levels did not differ between groups. Moderator analyses indicated that the relationship between the behavior perseverance facet of pain resilience and pain tolerance was significantly stronger among MS condition participants than controls.

Conclusions

This experiment is the first to document potential causal effects of MS on pain tolerance and Ms as a moderator of the association between self-reported behavior perseverance and behavioral pain tolerance. Findings provide foundations for extensions within clinical pain samples.

Creating Placebo Nonresponders in the Lab

Conditioning and expectation are known to be the main mechanisms of placebo analgesia. They may operate together, so that expectations may be enhanced by a conditioning procedure. Although most of the studies have tried to potentiate expectations through conditioning in order to generate good placebo responders, a few studies have tried to mismatch conditioning and expectations in order to investigate the subsequent administration of a placebo. In this study, we want to further investigate this mismatch. We generated incongruent associations during a conditioning procedure in which the study participants did not get what they expected. In fact, although the participants received verbal instructions of pain decrease following the administration of a placebo, we surreptitiously increased the painful electric stimulation. Two pairings of these incongruent associations (mismatch between what was expected and what was experienced) disrupted expectations of analgesia as well as the placebo effect, as assessed by measuring electric pain thresholds on the hand. The effects of mismatch conditioning on the hand extended to the contralateral arm and to a different type of pain (tourniquet), which suggests that local mismatch conditioning may affect the whole body. In all cases, expectations predicted placebo analgesia. These findings indicate that placebo nonresponders can be created in the laboratory by acting on expectations and that local effects can be generalized to other parts of the body. They also stress the importance of expectations in the therapeutic outcome, with important implications for clinical trials. PERSPECTIVE: By using mismatch conditioning, in which study participants did not get what they expected, we reduced expectations of analgesia, and this reduction abolished placebo analgesia. This effect extended to other parts of the body and other types of pain, which indicates that placebo nonresponders can be created in the laboratory.

Interaction between local blood flow and tolerance to prolonged pain in the elderly

PURPOSE

We aimed to explore the link between local vasodilation and pain perception in elderly subjects, testing the hypothesis that altered local cutaneous blood flow participates in the decrease in pain tolerance with age.

METHOD

Sixty-eight young and 83 older participants performed a pain tolerance test in which they hold their hand in an airtight box in which air temperature was regulated at 65 °C until the pain became unbearable. Participants continuously estimated pain intensity. Skin temperature and local blood flow in the box-exposed hand were continuously monitored.

RESULTS

In the young group, 97% of subjects resisted pain until the end of the test, whereas only 53% in the elderly group managed to do so, indicating that pain tolerance is impaired in the elderly. Among all participants, the skin temperature associated with the first pain sensation was below the threshold for nociceptor activation (43 °C). Interestingly, blood flow in the elderly group was correlated with pain judgment, whereas no such correlation was observed in the young.

CONCLUSION

Our results suggest that the local vasodilator response induced by local heating may be involved in pain perception and may influence thermal pain tolerance with aging. These results could contribute to a better understanding of vascular deficits and the development of chronic pain in vascular pathologies.

Pain tolerance and threshold in suicide attempters: A systematic review and meta-analysis

It has been hypothesized that individuals less sensitive to pain could be at higher risk of suicide. However, data on pain sensitivity in suicide attempters (SA) obtained using experimental procedures are heterogeneous. The aim of this systematic review and meta-analysis was to investigate and compare pain tolerance and threshold in SA (patients with lifetime history of suicide attempt), non-attempters (psychiatric controls, PC), and healthy controls (HC). A random effects meta-analysis was used to estimate the standardized mean differences using data from 16 studies that compared physical pain tolerance and threshold in SA and PC or HC. Pain tolerance and threshold were not significantly different in SA and PC. However, pain tolerance, but not threshold, was higher in SA than HC. Our findings do not support the hypothesis of an altered pain perception related as a trait for suicidal vulnerability, but rather suggest altered pain perception related to psychiatric vulnerability.

Intraoperative pain prediction of percutaneous kyphoplasty under local anesthesia by preoperative experimental pain assessment

BACKGROUND

Percutaneous kyphoplasty (PKP) is the preferred treatment for osteoporotic vertebral compression fractures (OVCF) Currently, the preoperative anesthesia methods for PKP are mainly local anesthesia and tracheal intubation general anesthesia.

OBJECTIVE

To assess whether patient sensitivity to pain measured preoperatively could predict the patients' pain response during PKP treatment under local anesthesia, to facilitate the development of an optimal preoperative anesthesia plan for patients.

METHODS

Fifty-five female patients diagnosed with osteoporotic single vertebral fracture who were treated with PKP under local anesthesia were selected. The patients' pain sensitivities, including pain threshold and pain tolerance threshold, were evaluated with a pain test device on the day before the operation in the ward. Heart rate (HR), mean arterial pressure (MAP), and blood oxygen saturation (SpO2) were recorded before anesthesia, post-anesthesia, after needle puncture, and after balloon dilatation. At the same time, blood was drawn at the above time points to determine the level of norepinephrine (NA) as an indicator of intraoperative pain stress response. The numerical rating scale (NRS) during surgery was recorded at the end of the surgery.

RESULTS

The preoperative pain tolerance threshold of 55 surgical patients was correlated with the intraoperative NRS score (r=-0.768, P< 0.001), as well as with the preoperative and intraoperative changes in HR (r=-0.791, P< 0.001), MAP (r=-0.819, P< 0.001), and NA (r=-0.553, P< 0.001). Thus, the lower the preoperative pain tolerance threshold, the more severe the patient's response to pain during PKP treatment under local anesthesia, and the greater the hemodynamic changes. Consequently, the intraoperative experience becomes worse. However, there was no correlation between preoperative pain threshold and NRS scores (r=-0.069, P= 0.616) nor between the preoperative and intraoperative changes in HR (r= 0.103, P= 0.453), MAP (r= 0.086, P= 0.535), and NA (r=-0.058, P= 0.674).

CONCLUSION

The results indicated that preoperative pain assessment could predict the level of pain response in OVCF patients during PKP surgery under local anesthesia.

Adversity type and timing predict temporal summation of pain in African-American adults

African Americans are disproportionately exposed to adversity across the lifespan, which includes both stressful and traumatic events. Adversity, in turn, is associated with alterations in pain responsiveness. Racial differences in pain responsiveness among healthy adults are well established. However, the extent to which adversity type and timing are associated with alterations in pain responsiveness among healthy African-American adults is not well understood. The present study included 160 healthy African-American adults (98 women), ages 18 to 45. Outcome measures included pain tolerance and temporal summation of pain to evoked thermal pain. Composite scores were created for early-life adversity (childhood trauma, family adversity) and recent adversity (perceived stress, chronic stress burden). A measure of lifetime racial discrimination was also included. Higher levels of recent adversity were associated with higher temporal summation of pain, controlling for gender, age, and education. Neither early-life adversity nor lifetime racial discrimination were associated with temporal summation of pain. The present findings suggest that heightened temporal summation of pain among healthy African-American adults is associated with exposure to recent adversity events. Improved understanding of how recent adversity contributes to heightened temporal summation of pain in African Americans could help to mitigate racial disparities in pain experiences by identifying at-risk individuals who could benefit from early interventions.

Can we improve exercise-induced hypoalgesia with exercise training? An overview and suggestions for future studies

Exercise-induced hypoalgesia refers to a reduction in pain sensitivity following a single bout of exercise, which has been shown to be diminished or impaired with aging and chronic pain. Exercise training (repeated bouts of exercise over time) is often recommended as a non-pharmacological treatment for chronic pain and age-related functional declines. However, whether exercise training can augment the exercise-induced hypoalgesia has not been well studied. The purpose of this paper is to 1) provide an overview of the existing literature investigating the effect of exercise training on the magnitude of exercise-induced hypoalgesia, and 2) discuss potential underlying mechanisms as well as considerations for future research. Given the paucity of randomized controlled trials in this area, the effects of exercise training on exercise-induced hypoalgesia are still unclear. Several potential mechanisms have been proposed to explain the impaired exercise-induced hypoalgesia in chronic pain and older individuals (e.g., endogenous opioid, cardiovascular, and immune system). Exercise training appears to induce physiological changes in those systems, however, further investigations are necessary to test whether this will lead to improved exercise-induced hypoalgesia. Future research should consider including a time- and age-matched non-training group and utilizing the same exercise protocol for testing exercise-induced hypoalgesia across intervention groups.

Intraindividual change in pain tolerance and negative affect over 20 years: findings from the MIDUS study

Pain tolerance, defined as the ability to withstand physical pain states, is a clinically important psychobiological process associated with several deleterious outcomes, including increased pain experience, mental health problems, physical health problems, and substance use. A significant body of experimental work indicates that negative affect is associated with pain tolerance, such that increased negative affect is associated with decreased pain tolerance. Although research has documented the associations between pain tolerance and negative affect, little work has examined these associations over time, and how change in pain tolerance is related to changes in negative affect. Therefore, the current study examined the relationship between intraindividual change in self-reported pain tolerance and intraindividual change in negative affect over 20 years in a large, longitudinal, observation-based national sample of adults (n = 4,665, Mage = 46.78, SD =12.50, 53.8% female). Results from parallel process latent growth curve models indicated that slope of pain tolerance and negative affect were associated with each other over time (r = .272, 95% CI [.08, .46] p = .006). Cohen's d effect size estimates provide initial, correlational evidence that changes in pain tolerance may precede changes in negative affect. Given the relevance of pain tolerance to deleterious health outcomes, better understanding how individual difference factors, including negative affect, influence pain tolerance over time, are clinically important to reduce disease-related burden.

Sensitivity to ostracism is blunted in suicide attempters only when they report suicidal ideation

BACKGROUND

Modified pain perception is at the core of many theories on suicide; however, studies on the relationship between pain perception and suicidal behavior (attempt) have produced contradictory results. In this experimental study, we investigated whether physical pain and social pain are concomitantly influenced by suicidal ideation (SI) and past suicidal behavior.

METHODS

155 inpatients with depression (90 with and 65 without past history of suicide attempt) were included. They underwent thermal stimulation of the skin to assess physical pain tolerance and played the Cyberball game to assess their sensitivity to ostracism (social pain). Participants self-assessed current SI through the specific item in the Beck Depression Inventory.

RESULTS

Pain tolerance was not associated with history of suicide attempt, current SI, and their interaction. Social pain was associated with the interaction between history of suicide attempt and current SI. Social pain was decreased in suicide attempters, compared with non-attempters, only when they reported current SI.

LIMITATIONS

Cyberball game may not be representative of everyday stress and ecological social context.

CONCLUSIONS

Unlike what suggested by many theories, pain tolerance does not seem to be necessary to attempt suicide. Suicide attempters with current SI displayed blunted sensitivity to ostracism and could be less willing to restore social affiliation compared with non-attempters.

Training-induced hypoalgesia and its potential underlying mechanisms

It is well-established that a single bout of exercise can reduce pain sensitivity (i.e., exercise-induced hypoalgesia) in healthy individuals. However, exercise-induced hypoalgesia is often impaired in individuals with chronic pain. This might suggest that repeated bouts of exercise (i.e., exercise training) are needed in order to induce a reduction in pain sensitivity (i.e., training-induced hypoalgesia) among individuals with chronic pain, given that a single bout of exercise seems to be insufficient to alter pain. However, the effect of repeated bouts of exercise on pain sensitivity and its underlying mechanisms remain poorly understood. Therefore, the purpose of this review was to provide an overview of the existing literature on training-induced hypoalgesia, as well as discuss potential mechanisms of training-induced hypoalgesia and offer considerations for future research. Existing literature suggests that training interventions may induce hypoalgesic adaptations potentially driven by central nervous system and immune system factors. However, the limited number of randomized controlled trials available, along with the lack of understanding of underlying mechanisms, provides a rationale for future research.

Sex and gender differences in pain

Chronic pain affects 20% of adults and is one of the leading causes of disability worldwide. Women and girls are disproportionally affected by chronic pain. About half of chronic pain conditions are more common in women, with only 20% having a higher prevalence in men. There are also sex and gender differences in acute pain sensitivity. Pain is a subjective experience made up of sensory, cognitive, and emotional components. Consequently, there are multiple dimensions through which sex and gender can influence the pain experience. Historically, most preclinical pain research was conducted exclusively in male animals. However, recent studies that included females have revealed significant sex differences in the physiological mechanisms underlying pain, including sex specific involvement of different genes and proteins as well as distinct interactions between hormones and the immune system that influence the transmission of pain signals. Human neuroimaging has revealed sex and gender differences in the neural circuitry associated with pain, including sex specific brain alterations in chronic pain conditions. Clinical pain research suggests that gender can affect how an individual contextualizes and copes with pain. Gender may also influence the susceptibility to develop chronic pain. Sex and gender biases can impact how pain is perceived and treated clinically. Furthermore, the efficacy and side effects associated with different pain treatments can vary according to sex and gender. Therefore, preclinical and clinical research must include sex and gender analyses to understand basic mechanisms of pain and its relief, and to develop personalized pain treatment.

Quantifying virtual reality pain modulation in healthy volunteers: A randomized, crossover study

STUDY OBJECTIVE

Virtual reality (VR) is an emerging tool to reduce pain and anxiety during procedures. Although VR's clinical benefits are reported, biometric data quantifying VR's effect on pain tolerance is lacking. We used time-lapse, subjective, and biometric data to evaluate VR's effect on modulating pain.

DESIGN

Randomized, controlled crossover within-subject clinical trial.

SETTING

This study was conducted in the Chariot Lab at Lucile Packard Children's Hospital and outdoors at Stanford University School of Medicine.

PATIENTS

156 healthy volunteers were included.

INTERVENTIONS

Participants underwent pain-inducing ice immersions while connected to biometric sensors. Participants were randomized to immerse their dominant or non-dominant hand with VR or control (no VR) for one immersion, and then crossed-over to the other hand for the second immersion. We instructed participants to submerge their hand until they reached their pain tolerance or until four minutes elapsed.

MEASUREMENTS

Outcomes included ice immersion duration, perceived pain scores, and skin conductance response density (SCRD), a marker of sympathetic arousal. We used survival analysis and mixed effects models to compare measurements with and without VR.

MAIN RESULTS

153 participants were included in the analysis. Participants with VR were 64% less likely to remove their hands from the ice bath throughout the immersion's duration compared to control (P < 0.001). Participants with VR reported significantly lower pain scores after controlling for dominant hand treatment assignment, VR vs. no VR treatment order, and gender (P < 0.001). SCRD increased as time progressed for both VR and control groups (P = 0.047 combined), with no significant mean group differences.

CONCLUSIONS

Participants with VR were more likely to survive the 4-min ice bath challenge longer and with lower levels of pain perception, supporting VR's effectiveness as a distraction tool during painful procedures. We observed no differences in sympathetic response when comparing VR to no VR.

The Negative Effect of Social Discrimination on Pain Tolerance and the Moderating Role of Pain Catastrophizing

This study examined the negative impact of social discrimination on the time to pain tolerance during experimentally induced cold pressor pain among healthy individuals. It was hypothesized that the degree to which one catastrophized about pain would exacerbate the negative impact of a history discriminatory experiences on pain tolerance, and that this interaction would be different between individuals of a racial and ethnic minority and non-Hispanic white individuals (thus testing catastrophizing as a moderated moderator). Higher levels of discrimination were positively related to catastrophic thinking about pain, and there was a significant negative relationship between the level of experienced discrimination and time to pain tolerance. Pain catastrophizing emerged as a significant moderator in that when pain catastrophizing levels were high, there was no association between social discrimination and pain tolerance. A history of social discrimination was significantly associated with reduced pain tolerance at low and moderate levels of pain catastrophizing. Racial minority status did not significantly alter this moderating relationship. Implications for the importance of assessing sociocultural variables, such as experiencing social discrimination in the clinical assessment of the individual with pain are outlined.

The indirect impact of heart rate variability on cold pressor pain tolerance and intensity through psychological distress in individuals with chronic pain: the Tromsø Study

Supplemental Digital Content is Available in the Text. The hypoalgesic impact of cardiovascular regulatory systems on evoked pain responsiveness in those with chronic pain is conveyed via the indirect effects of psychological distress.

Introduction:

Chronic pain (CP) patients often display lower heart rate variability (HRV) and baroreceptor sensitivity (BRS), which are associated with increased evoked pain intensity and decreased pain tolerance.

Objective:

The purpose of this study was to test whether the association between low levels of HRV and BRS and increased evoked pain responsiveness in individuals with CP is mediated by psychological distress and whether this mediation is sex dependent.

Methods:

The sample consisted of 877 participants in Wave 6 of the Tromsø population study who reported clinically meaningful CP. Resting HRV and BRS parameters were derived from continuous beat-to-beat blood pressure recordings. Psychological distress was assessed using the Hopkins Symptom Checklist-10. After cardiovascular assessment, participants completed a 106-second cold pressor task (3°C bath), which assessed cold pressor pain intensity (CPI) and cold pressor pain tolerance (CPT).

Results:

In the full CP sample, mediation analyses showed significant indirect effects, without direct effects, of HRV and BRS on both CPT and CPI via psychological distress. When stratified by sex, significant indirect effects via psychological distress were only found in males for the impact of rMSSD on CPT, the impact of SDNN on CPT, and the impact of BRS on CPT via psychological distress. Moderated mediation analyses revealed that there were no significant sex differences in the indirect effects of HRV and BRS on both CPT and CPI via psychological distress.

Conclusions:

The hypoalgesic impact of cardiovascular regulatory systems on evoked pain responses is conveyed via the indirect effects of psychological distress.

Sensitivity and pain in focal dystonia of the hand

INTRODUCTION

A growing body of evidence highlights the importance of understanding both the sensory and the motor pathophysiology of focal dystonia in order to improve its treatment. This study aims to evaluate somatosensory afferences in patients with focal or segmental dystonia affecting the upper limbs, to analyse whether the dominant limb is more frequently affected, to analyse pain tolerance, and to examine the potential association with pain perception in patients with hand dystonia.

METHODS

We recruited 24 participants: 12 patients with focal hand dystonia and 12 individuals without dystonia. All participants were evaluated with a digital algometer (Somedic SenseLab AB®, Farsta, Sweden), a Semmes-Weinstein monofilament test, and the visual analogue scale for pain.

RESULTS

According to our data, patients showed greater impairment in surface sensitivity than controls, both in the dominant and the non-dominant hands, as well as greater presence of pain (P > .001). Furthermore, the dystonia group showed a negative correlation between perceived pain and pressure pain tolerance threshold (rho = -0.83; P < .001).

CONCLUSIONS

Patients with focal hand dystonia presented alterations in sensitivity and more severe perceived pain than individuals without dystonia. Future studies with larger samples should aim to analyse the clinical implications and everyday impact of both objective and subjective pain.

Opioid-induced analgesia among persons with opioid use disorder receiving methadone or buprenorphine: A systematic review of experimental pain studies

BACKGROUND

Treating acute pain among persons with opioid use disorder (OUD) on opioid agonist therapy (OAT) is complex, and the therapeutic benefits of opioids remain unclear when weighted against their abuse potential and respiratory depressant effects.

METHODS

We conducted a systematic review of experimental pain studies examining opioid-induced analgesia among persons with OUD on OAT. We searched multiple databases from inception to July 30, 2021. Study quality was assessed by previously established validity measures.

RESULTS

Nine studies were identified, with a total of 225 participants, of whom 63% were male, and 37% were female. Six studies included methadone-maintained persons with OUD; four studies included buprenorphine-maintained persons with OUD; and three studies included healthy persons as comparison groups. Either additional doses of OAT or other opioids - morphine, oxycodone, hydromorphone, or remifentanil - were administered. In seven studies, persons with OUD on OAT did not experience analgesia, despite receiving opioid doses up to 20 times greater than those clinically used to treat severe pain among the opioid naïve. Conversely, in two studies, high-potency opioids did produce analgesia, albeit with greater abuse potential. Notably, persons with OUD on OAT remained vulnerable to respiratory depression.

CONCLUSIONS

Although persons with OUD on OAT can derive analgesic effects from opioids, high-potency compounds may be required to achieve clinically significant pain relief. Further, persons with OUD on OAT may remain vulnerable to opioid-induced abuse potential and respiratory depression. Together, these finding have clinical, methodological, and mechanistic implications for the treatment of acute pain in the context of OAT.

Isorhamnetin promotes functional recovery in rats with spinal cord injury by abating oxidative stress and modulating M2 macrophages/microglia polarization

Spinal cord injury (SCI), mostly caused by sports injuries, falls, or traffic accidents, is a major cause of disability. The aim of current work was to investigate the therapeutic effect of isorhamnetin (ISO) on functional recovery in rats with SCI. The male adult rats were exposed to a clip-compression SCI and treated with ISO. ISO treatment improved locomotor function and reduced the loss of motor neurons in SCI rats. Treatment with ISO markedly relieved SCI-induced hypersensitivities to mechanical and thermal stimulation in rats. ISO treatment activated nuclear factor-erythroid 2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1) pathway and abated oxidative stress in injured spinal cords. ISO treatment partly suppressed microglial and glial activation and reduced expression of inflammatory cytokines including TNF-α, monocyte chemotactic protein-1 (MCP-1), and IL-1β in injured spinal cords. More importantly, ISO treatment promoted M2 macrophage activation in the injured region. lipopolysaccharide (LPS) or IL-4 was employed to stimulate macrophages/microglia into M1 or M2 phenotype in cultured BV2 cells in vitro. ISO treatment enhanced the expression of characteristic microglial anti-inflammatory polarization markers in BV2 cells. In conclusions, ISO treatment promotes functional recovery in rats with SCI by abating oxidative stress and modulating M1/M2 macrophage polarization.

Older Patients More Accurately Predict Pain Tolerance After Lumbar Spine Fusion Compared with Their Younger Peers

OBJECTIVE

Patients undergoing spine surgery often inaccurately estimate their pain tolerance and postoperative analgesic requirement. We sought to identify an association between patients' self-perceived pain tolerance and postoperative opioid consumption (POC).

METHODS

We included adult patients undergoing elective lumbar spine decompression and fusion between 2014 and 2018. Patients with cognitive delay, psychiatric comorbidities, and perioperative complications were excluded. Demographic data, mean daily postoperative morphine milligram equivalents (MME), and pain tolerance scores were recorded.

RESULTS

Eighty-four patients met inclusion criteria. The median pain tolerance score was 8, which was used to defined a cutoff for high (≥8) and low (<8) pain tolerance. The average preoperative visual analog scale (VAS) pain score was higher in the high pain tolerance group (μ = 5.3) compared with the low pain tolerance group (μ = 4.0) (P = 0.01). Multivariate regression revealed pain tolerance was not predictive of mean daily postoperative MME use (P = 0.19). Age and preoperative VAS pain score were found to be negative (P < 0.0001) and positive (P = 0.027) independent predictors, respectively, of mean postoperative MME use. Patients 61 years and younger who reported high pain tolerance had higher POC compared with patients older than 61 years of age, who reported low (P = 0.036) pain tolerance.

CONCLUSIONS

Self-perceived pain tolerance does not appear to predict POC, while younger age and higher preoperative VAS pain scores are related to increased POC. Younger patients who report high pain tolerance appear to consume higher levels of opioids compared with older patients.

Pain perception and processing in individuals with posttraumatic stress disorder: a systematic review with meta-analysis

Supplemental Digital Content is Available in the Text.

Posttraumatic stress disorder encompasses latent subgroups of individuals with qualitative differences in pain perception.

Posttraumatic stress disorder (PTSD) is a known risk factor for the development of chronic pain conditions, and almost 1 in 5 individuals with chronic pain fulfills the criteria for PTSD. However, the relationship between PTSD and pain is poorly understood and studies on pain perception in patients with PTSD show inconsistent results suggesting that different sensory profiles exist among individuals with PTSD. Here, we (1) systematically summarize the current literature on experimentally evoked pain perception in patients with PTSD compared to subjects without PTSD, and (2) assess whether the nature of the traumatic event is associated with different patterns in pain perception. The main outcome measures were pain threshold, pain tolerance, and pain intensity ratings as well as measures of temporal summation of pain and conditioned pain modulation. A systematic search of MEDLINE, EMBASE, Web of Science, PsycINFO, and CINAHL identified 21 studies for the meta-analysis, including 422 individuals with PTSD and 496 PTSD-free controls. No main effect of PTSD on any outcome measure was found. However, stratification according to the nature of trauma revealed significant differences of small to medium effect sizes. Combat-related PTSD was associated with increased pain thresholds, whereas accident-related PTSD was associated with decreased pain thresholds. No clear relationship between PTSD and experimentally evoked pain perception exists. The type of trauma may affect pain thresholds differently indicating the presence of different subgroups with qualitative differences in pain processing.

No game, more pain - Examining possible long term effects and underlying mechanisms of habitual violent video gaming on the acquired capability for suicide

According to Joiner`s interpersonal-psychological theory of suicide repeated engagement in suicidal behavior or so-called painful and provocative events constitutes the acquired capability for suicide (ACS) comprising two facets: enhanced pain tolerance and fearlessness about death (FAD). Recent research showed that single bouts of violent-video-gaming (VVG) increase pain tolerance. It is unknown whether individuals who habitually play VVGs at a high frequency rate show higher signs of ACS in terms of low pain sensitivity, high tolerance and lowered FAD compared to non-gamers. In a cross-sectional case-control study, we compared pain sensitivity and tolerance during a 5-min Cold-Pressor-Test (CPT) besides FAD in young males, playing VVGs highly frequent (n = 18) vs. non-gamers (n = 17). Mood was rated before and after the CPT. We found higher CPT-pain tolerance, lower intensity ratings and higher FAD scores among gamers compared to non-gamers. A significant time x group interaction of pain ratings indicated a process of habituation in the gamers. An increase of positive mood in the gamers emphasizes the role of opponent processes. The results suggest that habitual VVG might reflect a repetitive behavior enhancing the ACS.

Validation of the German capability for suicide questionnaire (GCSQ) in a high-risk sample of suicidal inpatients

BACKGROUND

The German Capability for Suicide Questionnaire (GCSQ) was developed to measure fearlessness of death and pain tolerance - two constructs central to the Interpersonal Theory of Suicide. Initial scale development, definition of the factor structure and confirmation of the two-dimensional factor structure was performed in samples suffering from relatively low levels of suicide ideation/behavior. The present study aimed to validate the German Capability for Suicide Questionnaire (GCSQ) in a high-risk sample of suicidal inpatients.

METHODS

Factor structure, reliability and validity were investigated in a sample of inpatients (N = 296; 53.0% female; age in years: M = 36.81, SD = 14.27) admitted to a hospital due to a recent suicide attempt or an acute suicidal crisis (in immediate need of inpatient treatment). To establish convergent validity, interview-based assessments of lifetime suicide attempts and non-suicidal self-injury as well as questionnaire-based assessments of painful and provocative events were used. Finally, stability of GCSQ-scores over a follow-up period of 12 months was assessed.

RESULTS

Results indicated good psychometric properties, and provided additional evidence for construct validity and stability of the subscales over a one-year period, and demonstrated adequate fit of the data with respect to the original factor structure.

CONCLUSIONS

Results suggest that the GCSQ is a brief, reliable, and valid measure of capability for suicide that can be used in clinic assessment and research.

Sensitivity and pain in focal dystonia of the hand

INTRODUCTION

A growing body of evidence highlights the importance of understanding both the sensory and the motor pathophysiology of focal dystonia in order to improve its treatment. This study aims to evaluate somatosensory afferences in patients with focal or segmental dystonia affecting the upper limbs, to analyse whether the dominant limb is more frequently affected, to analyse pain tolerance, and to examine the potential association with pain perception in patients with hand dystonia.

METHODS

We recruited 24 participants: 12 patients with focal hand dystonia and 12 individuals without dystonia. All participants were evaluated with a digital algometer (Somedic SenseLab AB®, Farsta, Sweden), a Semmes-Weinstein monofilament test, and the visual analogue scale for pain.

RESULTS

According to our data, patients showed greater impairment in surface sensitivity than controls, both in the dominant and the non-dominant hands, as well as greater presence of pain (P>.001). Furthermore, the dystonia group showed a negative correlation between perceived pain and pressure pain tolerance threshold (rho=-0.83; P<.001).

CONCLUSIONS

Patients with focal hand dystonia presented alterations in sensitivity and more severe perceived pain than individuals without dystonia. Future studies with larger samples should aim to analyse the clinical implications and everyday impact of both objective and subjective pain.

Attention-deficit/hyperactivity disorder medication does not alter exercise-induced hypoalgesia following an acute bout of dynamic circuit resistance exercise

The primary goal of this study was to investigate the effects of attention-deficit/hyperactivity disorder (ADHD) medications on exercise-induced hypoalgesia (EIH), heart rate, and perceived exertion. Thirty college-age students (10 Controls, 10 ADHD diagnosis, and 10 ADHD diagnosis with medications) completed 2 sessions: 1) a maximal testing session and 2) an experimental session consisting of 3 consecutive dynamic resistance exercise circuits comprised of 12 repetitions of 9 exercises at 60% of 1-repetition maximum using a 1:1 work to rest ratio. All participants, regardless of condition (Controls vs. ADHD without medications vs. ADHD with medications), displayed EIH accompanied by an increase in blood lactate, heart rate, and perceived exertion for the duration of the exercise bout. Therefore, the effects of resistance exercise are not altered by ADHD diagnosis or psychostimulant medication use for ADHD. These findings are intriguing given the known ergogenic and hypoalgesic effects of caffeine, a less potent stimulant.

Relationship between Serum Methadone Concentration and Cold Pressor Pain Sensitivity in Patients Undergoing Methadone Maintenance Therapy

Hyperalgesia is a common clinical phenomenon among opioid dependent patients on methadone maintenance therapy (MMT) and it may be associated with undertreated pain and/or therapeutic failure. This study aimed to investigate association between serum methadone concentration (SMC) and cold pressor pain responses. Cold pressor pain responses in 147 opioid dependent patients on MMT were assessed using cold pressor test (CPT) at 0 h and at 2, 4, 8, 12, and 24 h after the dose intake. Blood samples were collected at 24 h after the dose. Serum methadone concentrations were measured using the Methadone ELISA kit and classified into two categories: < 400 ng/mL and ≥ 400 ng/mL. Eighty-eight patients (59.9%) had trough concentrations of < 400 ng/mL and 40.1% had trough concentrations of ≥ 400 ng/mL. There were significant effects of SMC on the cold pressor pain threshold (p = 0.019). Patients with concentrations < 400 ng/mL had significantly higher (almost 60% higher) cold pressor pain threshold (adjusted mean (95% CI) = 30.15 (24.29, 36.01) s) compared to those with concentrations of ≥ 400 ng/mL (18.93 (11.77, 26.08) seconds). There was also a 20% difference in pain tolerance, and 6% difference in cold pressor pain intensity score, neither of which were significant statistically (p > 0.05). Our results suggest an association of trough methadone concentration with the cold pressor pain threshold among opioid dependent patients on MMT. It would be useful to study the mechanisms underlying this association to help managing pain in such a population.

Methylphenidate attenuates the response to cold pain but not to aversive auditory stimuli in healthy human: a double-blind randomized controlled study

This double-blind, crossover, randomized placebo-controlled study found that methylphenidate has a specific effect on nociceptive pathways rather than a generalized effect on aversive sensory modalities.

Introduction:

We recently showed that the psycho-stimulant norepinephrine–dopamine reuptake inhibitor methylphenidate (MP) prolonged cold pain threshold and tolerance in adults with attention-deficit hyperactivity disorder (ADHD).

Objectives:

The objectives of the present study were to: (1) examine whether MP has antinociceptive properties in healthy men; (2) test MP's effects on responses to aversive auditory stimuli. The underlying aim was to determine whether MP exerts antinociceptive properties or more generalized, nonspecific attenuating effects on different aversive sensory modalities.

Methods:

This double-blind, crossover, randomized placebo-controlled study consisted of 2 sessions one week apart from each other. In each session, pain threshold (seconds) and tolerance (seconds) in response to painful cold stimulation were measured. Additionally, threshold (dB) and tolerance (seconds) to loud aversive auditory stimuli (500 Hz, 2000 Hz and white noise) were also tested prior to and 2 hours following the administration of a single dose of either 20 mg MP or an identical looking placebo.

Results:

Forty men, 26.1 ± 4.0 (mean ± SD) years were enrolled in the study. Wilcoxon signed-rank test analyses showed that MP, but not the placebo, produced a significant increase in cold pain threshold (from 4.1 ± 2.6 to 5.4 ± 3.1 seconds, P = 0.001 and from 4.5 ± 2.6 to 4.3 ± 2.7 seconds, P = 0.2, respectively) and tolerance (from 57.8 ± 54.0 to 73.8 ± 61.8 seconds, P = 0.001 and from 52.5 ± 53.7 sec to 57.0 ± 52.9 seconds, P = 0.1, respectively). No significant changes were found in any of the auditory parameters.

Conclusion:

These results suggest that MP has an effect on nociceptive pathways rather than a nonspecific, generalized attenuating effect on aversive sensory stimuli.

Parental-reported pain insensitivity in Dup15q

Parents of children with chromosome 15q duplication syndrome (Dup15q) have anecdotally reported high pain threshold as a feature of the disorder. The purpose of this study was to document parental-reported estimates of the frequency of high pain tolerance and the stimuli that fail to evoke a normal pain response. We sent an online survey to 840 families with children with Dup15q to explore the frequency and clinical manifestations of high pain threshold. There were 216 respondents (25.7%). A high pain threshold was reported in 87% of children at some time. There was a trend (p=0.06) for high pain threshold to be more commonly observed among children with the isodicentric (85.6%) and other genetic variants (95%) than interstitial (69.6%) duplications. There was no association between reports of high pain threshold and reports of an intellectual disability (91% of cases), autism spectrum disorder (83% of cases), or self-injurious behavior (40% of cases). Reports included many dramatic cases such as severe burns, broken bones, and electrical traumas, which were associated with little or no evidence of a painful stimulus. A high pain threshold is reported in other disorders associated with intellectual disability and autism; the underlying mechanism in Dup15q and other disorders remains undefined.

An investigation into enlarging and reducing the size of mirror reflections of the hand on experimentally-induced cold-pressor pain in healthy human participants

BACKGROUND AND AIMS

Mirror visual feedback may be a useful clinical tool for reducing pain. Research suggests that reducing the size of a non-painful reflected hand can alleviate complex regional pain syndrome in the affected hand that is out of view. In contrast, research on healthy humans exposed to experimentally induced pain suggests that reducing the appearance of the size of a reflected body part can increase pain. The aim of this study was to investigate the effect of enlarging and reducing the visual appearance of the size of a hand using mirror visual feedback on pain threshold, intensity and tolerance in healthy human participants exposed to cold-pressor pain.

METHODS

Participants were a convenience sample of 20 unpaid, healthy pain free volunteers aged 18 years or above. Each participant took part in one experiment where they completed cold-pressor pain tests whilst observing normal, enlarged and reduced size reflections of a hand congruent to a hand immersed in the ice cold water. A 4×2 factorial repeated measures analysis of variance (ANOVA) was performed on time to pain threshold and pain tolerance, and pain intensity with Condition (four levels: no reflection, reduced reflection, normal reflection, enlarged reflection) being the within-subject factors and Sex (two levels: female, male) between-subject factors.

RESULTS

There were no significant effects for Condition, Sex, or Condition×Sex interaction for pain threshold, intensity or tolerance (p>0.05). There were no significant differences between the 3 mirror reflection conditions for agreement with the statements: "It felt like I was looking directly at my hand rather than at a mirror image"; "It felt like the hand I was looking at was my hand"; and "Did it seem like the hand you saw was a right hand or a left hand?".

CONCLUSION

Enlarging or reducing the size of a hand using mirror visual feedback did not alter pain perception in healthy human participants exposed to cold-pressor pain. The different sizes of hands generated by mirror visual feedback created an illusion of looking at their own hand but this was not as strong as looking directly at the hand.

IMPLICATIONS

In future, investigators and clinicians using mirror visual feedback may consider including an adaptive phase to ensure the reflection has been perceptually embodied. Reasons for the lack of effects are explored to inspire further research in the field.

The Opposing Roles of IVS2+691 CC Genotype and AC/AG Diplotype of 118A>G and IVS2+691G>C of OPRM1 Polymorphisms in Cold Pain Tolerance Among Opioid-Dependent Malay Males on Methadone Therapy

Introduction

We recently reported that a majority of opioid-dependent Malay males on methadone therapy are cold pain sensitive. It is postulated that common OPRM1 polymorphisms may be responsible. This study investigated the association between 118A>G (dbSNP rs1799971) and IVS2+691G>C (dbSNP rs2075572) variants on cold pain responses among opioid-dependent Malay males on methadone maintenance therapy.

Methods

Cold pain responses including pain threshold, pain tolerance, and pain intensity were measured using the cold pressor test. DNA was extracted from the venous blood before polymerase chain reaction genotyping. Repeated measures analysis of variance was used to compare the cold pain responses and OPRM1 polymorphisms (118A>G and IVS2+691G>C) using models including genotype dominant and recessive models, allelic additive models, and analysis of haplotypes and diplotypes.

Results

A total of 148 participants were recruited. With the recessive model, those with IVS2+691 homozygous CC genotype had a shorter cold pain tolerance time than those without CC genotype (i.e., GG/GC genotype; 29.81 vs. 43.08 s, respectively, P = 0.048). On the other hand, with diplotype analysis, participants with combined homozygous 118 AA genotype and heterozygous IVS2+691 GC genotype (i.e., AC/AG diplotype) had a longer cold pain tolerance time than those without this diplotype (49.34 vs. 31.48 s, respectively, P = 0.043). Cold pain threshold was not associated with any of the 118A>G and IVS2+691G>C variations despite being analyzed using various models (all P > 0.05).

Conclusion

The IVS2+691 CC genotype and AC/AG diplotype of 118A>G and IVS2+691G>C seem to have opposing roles in pain tolerance among opioid-dependent Malay males on methadone therapy. Haplotypes of OPRM1 may be associated with altered binding affinity.

Electronic supplementary material

The online version of this article (doi:10.1007/s40122-015-0041-y) contains supplementary material, which is available to authorized users.

Feeling the burn: When it looks like it hurts, and belongs to me, it really does hurt more

We examined changes in pain sensitivity in the rubber hand illusion (RHI). Experiment 1 investigated changes in pain tolerance immediately after a "healthy" and "wounded" RHI when immersing the hand in a cold pressor ice bath. There was 19% increased pain tolerance and increased perception detection threshold after the healthy RHI, but 11% reduction after the wounded RHI. Experiment 2 examined pain experience during the wounded RHI with capsaicin-induced hyperalgesia. Pain intensity and unpleasantness was higher on the illusion arm during the synchronous RHI, compared with asynchronous trials. There was no change in pain experience on the control arm, and both arms had similar pain sensitivity after the experiment. Our results highlight the impact of embodying a substitute limb on pain, with increased tolerance and reduced tactile sensitivity when the fake limb is healthy and apparently pain-free, but increased pain sensitivity when the self-attributed limb appears to be wounded.

Pain perception in major depressive disorder: a neurophysiological case-control study

BACKGROUND

Depression and pain may sometimes be related conditions. Occasionally, depression may be associated with physical symptoms, such as back pain and headache. Moreover, depression may impair the subjective response to pain and is likely to influence the pain feeling. Conversely, chronic pain may represent an emotional condition as well as physical sensation, and can influence both the mood and behaviour.

AIM

To better understand the relationship between pain and depression, we therefore assessed the pain threshold and the tolerance pain threshold in patients with depressive disorders.

MATERIALS AND METHODS

We conducted a case-control study and selected patients who had recently received a diagnosis of major depression (DSM-IV), before treatment, and without any significant pain complaints. Age- and sex-matched healthy controls were also included. Tactile and pain thresholds were assessed in all subjects through an electrical stimulation test. All results were compared between the groups.

RESULTS

27 patients and 27 age-matched healthy controls were included in the study. Tactile, pain and tolerance thresholds were evaluated in all subjects. The pain threshold and pain tolerance were lower in patients with major depression than controls. All differences were statistically significant (p<0.05).

CONCLUSION

These results suggest the abnormal processing of pain stimuli in depressive disorders.

Negative affectivity predicts decreased pain tolerance during low-grade inflammation in healthy women

INTRODUCTION

Experimental animal studies provided evidence for a synergistic effect of immunological and psychological stressors on subsequent sickness behaviours. Up to now, little corroborating evidence for such synergy exists for humans, in whom it may provide a mechanism leading to the expression of functional somatic symptoms. The aim of the present study was to determine an interaction between stress(-vulnerability) and an immunological activation on experimental pain sensitivity, i.e., pressure pain threshold and tolerance in healthy humans.

METHODS

In healthy female participants (n=25, mean age 22.3 years), negative affectivity (NA) and experienced stress were assessed by questionnaire before receiving a Salmonella typhi vaccine or saline control in a randomized blinded cross-over design. Pressure pain threshold was assessed at the lower back and calves and pain tolerance was assessed at the thumbnail, before and six hours after each injection.

RESULTS

Vaccination induced leukocytosis (+100%) and increased serum IL-6 (+670%). NA predicted decreased pain tolerance after vaccination (β=-.57, p=.007), but not after placebo (β=.25, p=.26). Post-hoc analyses also demonstrated an association with administration order.

DISCUSSION

NA moderated the effects of inflammation on pain tolerance. This finding is consistent with a synergistic model whereby inflammation may lower the threshold for pain reporting in individuals with increased vulnerability for somatic symptom reporting.

Pain tolerance, pain sensitivity, and accessibility of aggression-related schemata in parents at-risk for child physical abuse

This study examined whether parents with varying degrees of child physical abuse (CPA) risk differed in pain tolerance, pain sensitivity, and accessibility of aggression-related schemata. Participants included 91 (51 low CPA risk and 40 high CPA risk) general population parents. Participants were randomly assigned to complete either an easy or a difficult anagram task. Pain tolerance and pain sensitivity were assessed using a cold pressor task. Accessibility of aggression-related schemata was assessed at the outset of the data collection session and at the end of the session using a word completion task. Parents' self-reported negative affect was assessed three times over the course of the study: baseline, after the anagram task, and after the cold pressor task. As expected, high-risk (compared to low-risk) parents reported higher levels of negative affect at each time point. Moreover, after completing the difficult anagram task, high-risk (compared to low-risk) parents exhibited higher pain sensitivity during the cold pressor task. Following completion of the cold pressor task, high-risk (compared to low-risk) parents exhibited greater accessibility of aggression-related schemata. Collectively, these findings indicate that under certain conditions, high-risk parents experience a confluence of aggression-related risk factors (i.e., negative affect, pain sensitivity, and aggression-related information processes) that may predispose them to aggressive behavior.

Acute psychosocial stress reduces pain modulation capabilities in healthy men

Anecdotes on the ability of individuals to continue to function under stressful conditions despite injuries causing excruciating pain suggest that acute stress may induce analgesia. However, studies exploring the effect of acute experimental stress on pain perception show inconsistent results, possibly due to methodological differences. Our aim was to systematically study the effect of acute stress on pain perception using static and dynamic, state-of-the-art pain measurements. Participants were 29 healthy men who underwent the measurement of heat-pain threshold, heat-pain intolerance, temporal summation of pain, and conditioned pain modulation (CPM). Testing was conducted before and during exposure to the Montreal Imaging Stress Task (MIST), inducing acute psychosocial stress. Stress levels were evaluated using perceived ratings of stress and anxiety, autonomic variables, and salivary cortisol. The MIST induced a significant stress reaction. Although pain threshold and pain intolerance were unaffected by stress, an increase in temporal summation of pain and a decrease in CPM were observed. These changes were significantly more robust among individuals with stronger reaction to stress ("high responders"), with a significant correlation between the perception of stress and the performance in the pain measurements. We conclude that acute psychosocial stress seems not to affect the sensitivity to pain, however, it significantly reduces the ability to modulate pain in a dose-response manner. Considering the diverse effects of stress in this and other studies, it appears that the type of stress and the magnitude of its appraisal determine its interactions with the pain system.

Adaptability to pain is associated with potency of local pain inhibition, but not conditioned pain modulation: a healthy human study

This study investigated the relationship between pain sensitivity, adaptability, and potency of endogenous pain inhibition, including conditioned pain modulation (CPM) and local pain inhibition. Forty-one healthy volunteers (20 male, 21 female) received conditioning stimulation (CS) over 2 sessions in a random order: tonic heat pain (46 °C) on the right leg for 7 minutes and cold pressor pain (1 °C to 4 °C) on the left hand for 5 minutes. Participants rated the intensity of pain continuously using a 0 to 10 electronic visual analogue scale. The primary outcome measures were pressure pain thresholds (PPT) measured at the heterotopic and homotopic location to the CS sites before, during, and 20 minutes after CS. Two groups of participants, pain adaptive and pain nonadaptive, were identified based on their response to pain in the cold pressor test. Pain-adaptive participants showed a pain reduction between peak pain and pain at end of the test by at least 2 of 10 (n=16); whereas the pain-nonadaptive participants reported unchanged peak pain during 5-minute CS (n=25). Heterotopic PPTs during the CS did not differ between the 2 groups. However, increased homotopic PPTs measured 20 minutes after CS correlated with the amount of pain reduction during CS. These results suggest that individual sensitivity and adaptability to pain does not correlate with the potency of CPM. Adaptability to pain is associated with longer-lasting local pain inhibition.

Influence of violent video gaming on determinants of the acquired capability for suicide

The interpersonal theory of suicidal behavior proposes that fearlessness of death and physical pain insensitivity is a necessary requisite for self-inflicted lethal self-harm. Repeated experiences with painful and provocative events are supposed to cause an incremental increase in acquired capability. The present study examined whether playing a first-person shooter-game in contrast to a first-person racing game increases pain tolerance, a dimension of the acquired capability construct, and risk-taking behavior, a risk factor for developing acquired capability. N=81 male participants were randomly assigned to either play an action-shooter or a racing game before engaging in a game on risk-taking behavior and performing a cold pressor task (CPT). Participants exhibited higher pain tolerance after playing an action shooter game than after playing a racing game. Furthermore, playing an action shooter was generally associated with heightened risk-taking behavior. Group-differences were not attributable to the effects of the different types of games on self-reported mood and arousal. Overall these results indicate that action-shooter gaming alters pain tolerance and risk-taking behavior. Therefore, it may well be that long-term consumption of violent video games increases a person's capability to enact lethal self-harm.

Music can effectively reduce pain perception in women rather than men

Objective: Nowadays music is used to decrease pain and increase relaxation in clinical settings. It is hypothesized that music can affect women more easily than men. We assessed the effect of two types of music (Iranian folkloric and preferred music) on pain tolerance and pain rating in cold pressor test.

Methodology: A consecutive sample of 50 healthy Iranian medical students was enrolled. They reported pain tolerance and pain rating in cold pressor test in three different musical conditions served as the outcome measures. The results were analyzed with repeated measurement analysis of variance.

Result: Mean tolerance time was significantly higher in preferred music compared to Iranian folkloric music (F (1,48) =25.44, p=0.0001) and no music (F(1,48)=3.51, p=0.0001) conditions. There was a significant interaction when tolerance time in no music condition was compared to preferred music condition, regarding sex; Tolerance time increased more in females (F(1,48)=5.53, p=0.023). The results also indicated that pain ratings, regardless of sex, were different in three musical conditions (F(1.7,81.34)=15.37, p=0.0001).

Conclusion: Music distracted attention from pain and Women can be impressed and distracted more easily by music.

Persistent post-surgical pain and experimental pain sensitivity in the Tromsø study: comorbid pain matters

In a large survey incorporating medical examination (N=12,981), information on chronic pain and surgery was collected, and sensitivity to different pain modalities was tested. Tolerance to the cold pressor test was analysed with survival statistics for 10,486 individuals, perceived cold pressor pain intensity was calculated for 10,367 individuals, heat pain threshold was assessed for 4,054 individuals, and pressure pain sensitivity for 4,689 individuals. Persistent post-surgical pain, defined by self-report, was associated with lower cold pressor tolerance (sex-adjusted hazard ratio=1.34, 95% confidence interval=1.08-1.66), but not when adjusting for other chronic pain. Other experimental pain modalities did not differentiate between individuals with or without post-surgical pain. Of the individuals with chronic pain (N=3352), 6.2% indicated surgery as a cause, although only 0.5% indicated surgery as the only cause. The associations found between persistent post-surgical pain and cold pressor tolerance is largely explained by the co-existence of chronic pain from other causes. We conclude that most cases of persistent post-surgical pain are coexistent with other chronic pain, and that, in an unselected post-surgical population, persistent post-surgical pain is not significantly associated with pain sensitivity when controlling for comorbid pain from other causes. A low prevalence of self-reported persistent pain from surgery attenuates statistically significant associations. We hypothesize that general chronic pain is associated with central changes in pain processing as expressed by reduced tolerance for the cold pressor test.

Children's selective attention to pain and avoidance behaviour: the role of child and parental catastrophizing about pain

The present study investigated selective attention to pain in children, its implications for child avoidance behaviour, and the moderating role of dimensions comprising child and parental catastrophizing about pain (ie, rumination, magnification, and helplessness). Participants were 59 children (31 boys) aged 10-16 years and one of their parents (41 mothers). Children performed a dot-probe task in which child facial pain displays of varying pain expressiveness were presented. Child avoidance behaviour was indexed by child pain tolerance during a cold-pressor task. Children and parents completed measures of child and parent pain catastrophizing, respectively. Findings indicated that both the nature of child selective attention to pain and the impact of selective attention upon child avoidance behaviour were differentially sensitive to specific dimensions of child and parental catastrophizing. Specifically, findings showed greater tendency to shift attention away from pain faces (i.e.,, attentional avoidance) among children reporting greater pain magnification. A similar pattern was observed in terms of parental characteristics, such that children increasingly shifted attention away from pain with increasing levels of parental rumination and helplessness. Furthermore, child attentional avoidance was associated with greater avoidance behaviour (i.e., lower pain tolerance) among children reporting high levels of pain magnification and those whose parents reported greater rumination about pain. The current findings corroborate catastrophizing as a multidimensional construct that may differentially impact outcomes and attest to the importance of assessing both child and parental characteristics in relation to child pain-related attention and avoidance behaviour. Further research directions are discussed.