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

Conflicts hurt: social stress predicts elevated pain and sadness after mild inflammatory increases

ABSTRACT

Individuals respond differently to inflammation. Pain, sadness, and fatigue are common correlates of inflammation among breast cancer survivors. Stress may predict response intensity. This study tested whether breast cancer survivors with greater exposure to acute or chronic social or nonsocial stress had larger increases in pain, sadness, and fatigue during an acute inflammatory response. In total, 156 postmenopausal breast cancer survivors (ages 36-78 years, stage I-IIIA, 1-9 years posttreatment) were randomized to either a typhoid vaccine/saline placebo or the placebo/vaccine sequence, which they received at 2 separate visits at least 1 month apart. Survivors had their blood drawn every 90 minutes for the next 8 hours postinjection to assess levels of interleukin-6 and interleukin-1 receptor antagonist (IL-1Ra). Shortly after each blood draw, they rated their current levels of pain, sadness, and fatigue. Women also completed the Test of Negative Social Exchange to assess chronic social stress and the Trier Inventory of Chronic Stressors screen to index chronic general stress. At each visit, a trained experimenter administered the Daily Inventory of Stressful Events to assess social and nonsocial stress exposure within the past 24 hours. After statistical adjustment for relevant demographic and behavioral covariates, the most consistent results were that survivors who reported more chronic social stress reported more pain and sadness in response to IL-1Ra increases. Frequent and ongoing social stress may sensitize the nervous system to the effects of inflammation, with potential implications for chronic pain and depression risk among breast cancer survivors.

Risk factors associated with the prevalence of neck and shoulder pain among high school students: a cross-sectional survey in China

BACKGROUND

After the COVID-19 outbreak, many Chinese high school students have increased their dependence on electronic devices for studying and life, which may affect the incidence of neck and shoulder pain (NSP) in Chinese adolescents.

METHODS

To evaluate the prevalence of NSP in high school students and its associated risk factors during COVID-19, a survey was conducted among 5,046 high school students in Shanghai, Qinghai, Henan and Macao during the second semester and summer vacation of the 2019-2020 academic year. The questionnaire included questions regarding demographic characteristics, the prevalence of NSP and lifestyle factors such as sedentary behavior, poor posture and electronic device usage. Univariable and multivariable logistic regression was used to analyze the possible influencing factors for neck and shoulder pain.

RESULTS

A total of 4793 valid questionnaires (95.0%) were collected. The results indicated that the prevalence of NSP was 23.7% among high school students. Binary logistic regression analysis revealed that female gender (P < 0.05, OR = 1.82), grade (P < 0.05, range OR 1.40-1.51) and subject selection (P < 0.05, range OR 0.49-0.68) were risk factors for NSP in high school students. Sedentary behavior (P < 0.05, range OR 1.74-2.36), poor posture (P < 0.05, range OR 1.19-2.56), backpack weight (P < 0.05, range OR 1.17-1.88), exercise style and frequency (P < 0.05, range OR 1.18-1.31; P < 0.05, range OR 0.76-0.79, respectively), and the time spent using electronic devices (P < 0.05, range OR 1.23-1.38)had a significant correlation with NSP in high school students.

CONCLUSIONS

NSP is currently very common among high school students during the outbreak of COVID-19. Sedentary behavior, poor posture and other factors have a great impact on the occurrence of NSP in high school students. Education regarding healthy lifestyle choices should be advocated for to decrease NSP among high school students, such as more physical activity, changing poor postures and reducing the amount of time spent using electronic devices.

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.

Typhoid vaccine does not impact feelings of social connection or social behavior in a randomized crossover trial among middle-aged female breast cancer survivors

BACKGROUND

Inflammation can have social consequences, which may be relevant to inflammation's link with depression. The current study tests whether a typhoid vaccine increases feelings of social disconnection and avoidance behavior.

METHOD

In two full-day visits at least three weeks apart, 172 postmenopausal breast cancer survivors (Stage I-IIIA) each received a typhoid capsular polysaccharide vaccination and a saline placebo injection in a random sequence. Blood was drawn prior to the injection, as well as every 90 min thereafter for 8 h to assess the inflammatory response (interleukin-6, IL-6; interleukin-1 receptor antagonist, IL-1Ra). At both visits, women completed the Social Connection Scale at 0 and 8.5 h post-vaccination as well as implicit and explicit social avoidance tasks at 7 h post-vaccination.

RESULTS

The typhoid vaccine triggered rises in both inflammatory markers (ps < 0.01), but it did not impact feelings of social connection (p = .32), or performance on the implicit (p = .34) or explicit tasks (p = .37). Inflammatory rises did not predict feelings of social connection (ps > 0.64) or performance on explicit (ps > 0.73) or implicit (ps > 0.88) social avoidance tasks.

CONCLUSION

Milder inflammatory stimuli may not affect social processes. Higher levels of inflammation or, relatedly, more sickness symptoms may be necessary to recapitulate prior findings of social avoidance.

Breast cancer survivors' typhoid vaccine responses: Chemotherapy, obesity, and fitness make a difference

PURPOSE

To investigate breast cancer survivors' inflammatory responses to typhoid vaccine as a window into their innate immune response to novel pathogens.

METHODS

This double-blind crossover trial randomized 158 breast cancer survivors to either the vaccine/saline placebo or the placebo/vaccine sequence. The relative contributions of age, cardiorespiratory fitness (VO_2peak), type of cancer treatment, central obesity, and depression to interleukin (IL)-6, IL-1 receptor antagonist (IL-1Ra), and WBC vaccine responses were assessed pre-injection and 1.5, 3, 4.5, 6, and 7.5 h post-injection.

RESULTS

The vaccine produced larger IL-6, IL-1Ra, and WBC responses than placebo, ps < 0.0001. Prior chemotherapy, higher central obesity, and lower VO_2peak were associated with smaller vaccine responses after controlling for baseline inflammation. Vaccine response was summarized by the percent increase in area under the curve (IL-6, WBC) or average post-injection mean (IL-1Ra) for vaccine relative to placebo. Women who received chemotherapy had smaller vaccine responses than women who did not for both IL-6 (44% vs 78%, p <.001) and WBC (26% vs 40%, p <.001); IL-1ra response was not significantly moderated by chemotherapy. Women whose central adiposity was one standard deviation above the mean had smaller vaccine responses than women with average adiposity for IL-6 (33% vs 54%, p <.001), WBC (20% vs 30%, p <.001), and IL-1Ra (2.0% vs 3.2%, p <.001). Women with an average level of VO_2peak had smaller vaccine responses than women whose VO_2peak was one standard deviation above the mean for IL-6 (54% vs 73%, p <.001), WBC (30% vs 40%, p <.001), and IL-1Ra (3.2% vs. 4.1%, p = 0.01). Age and depression did not significantly moderate vaccine responses.

CONCLUSIONS

This study provided novel data on chemotherapy's longer-term adverse immune consequences. The data also have an important public health message: even relatively low levels of fitness can benefit the innate immune response to a vaccine.

Individuals with both higher recent negative affect and physical pain have higher levels of C-reactive protein

Conceptualizing physical pain and negative affect as potentially interactive, we hypothesized that higher levels of peripheral inflammatory markers would be observed consistently only among individuals with both higher negative affect and pain symptomatology. Participants were generally healthy midlife adults from the Bronx, NY (N ​= ​212, M_age ​= ​46.77; 60.8% Black, 25.5% Hispanic/Latina/o) recruited as part of a larger study. Key measures were: reported pain intensity and pain interference at baseline, recent negative affect averaged from self-reports 5x/day for 7 days, and peripheral inflammatory markers (C-reactive protein [CRP] and a composite cytokine measure based on seven cytokines). Controlling for age, BMI, gender, and education, recent negative affect significantly interacted with both pain variables to explain variance in CRP, with higher CRP levels observed only in individuals with both higher negative affect and either higher pain intensity or pain interference. These findings contribute to an emerging literature suggesting that negative affect, pain, and inflammation are related in important and complex ways.

Back to the future of psychoneuroimmunology: Studying inflammation-induced sickness behavior

What do we know about sickness behavior? In this article, I guide you through some of the complexity of sickness behavior occurring after an immune challenge. I highlight the many features of behavioral and affective changes induced during experimental endotoxemia in humans, and describe how little we know about many of these features. I argue that we need to dismantle the components of inflammation-induced sickness behavior, and study each component in detail. I also point out the large inter-individual differences in inflammation-induced behavioral and affective changes, and the fact that psychosocial factors likely interact with inflammation to shape inflammation-induced sickness behavior. PNI clearly lacks investigations of the vulnerability and resilient factors underlying the inter-individual variability in sickness behavior. Throughout the article, I base my argument on my published articles, and provide concrete examples from my experience and the data that I have collected over the past 10 years. Given the relevance of inflammation-induced sickness behavior for inflammation-associated depression and for how people react to infections, I encourage current and future psychoneuroimmunologists to return towards basic science of sickness behavior.

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Inflammation-related sickness behavior is relevant for inflammation-associated depression

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The many features of sickness behavior should be investigated in detail

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There are large inter-individual variability in sickness behavior

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Vulnerability and resilient factors predicting sickness responses are little known

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I call for a return towards basic science of sickness behavior.

Sick for science: experimental endotoxemia as a translational tool to develop and test new therapies for inflammation-associated depression

Depression is one of the global leading causes of disability, but treatments remain limited and classical antidepressants were found to be ineffective in a substantial proportion of patients. Thus, novel effective therapies for the treatment of depression are urgently needed. Given the emerging role of inflammation in the etiology and pathophysiology of affective disorders, we herein illustrate how experimental endotoxemia, a translational model of systemic inflammation, could be used as a tool to develop and test new therapeutic options against depression. Our concept is based on the striking overlap of inflammatory, neural, and affective characteristics in patients with inflammation-associated depression and in endotoxin-challenged healthy subjects. Experimental administration of endotoxin in healthy volunteers is safe, well-tolerated, and without known long-term health risks. It offers a highly standardized translational approach to characterize potential targets of therapies against inflammation-associated depression, as well as to identify characteristics of patients that would benefit from these interventions, and, therefore, could contribute to improve personalization of treatment and to increase the overall rate of responders.

Attenuating Pain With the Past: Nostalgia Reduces Physical Pain

Previous work has found that nostalgia, a sentimental longing for the past, is associated with psychological, emotional, and social benefits. Recent research has demonstrated that nostalgic reflection also can improve individuals’ physical health (i.e., exercise) and reduce temperature-related pain. Building on this, two experiments examined how nostalgia can reduce people’s pain perceptions (i.e., reduced severity and increased tolerance). Specifically, Study 1 showed that inducing nostalgia through a writing task decreased perceived pain severity (i.e., intensity) among self-reported chronic pain sufferers. Study 2, in turn, demonstrated that Japanese individuals experienced increased pain tolerance (i.e., the maximum level of pain a person can tolerate) for a pressure algometer task following thoughts of nostalgia (vs. a control prime). This work provides evidence that nostalgic reflection may serve as a psychological resource to reduce the perceived severity of physical pain.

Elucidating vulnerability to inflammation-induced hyperalgesia: Predictors of increased musculoskeletal pain sensitivity during experimental endotoxemia

Despite broad clinical implications, the mechanisms linking inflammation and pain remain incompletely understood. Using human experimental endotoxemia as a translational model of systemic inflammation, we aimed to elucidate putative vulnerability factors of inflammation-induced musculoskeletal hyperalgesia. We pooled data from three published randomized controlled trials, resulting in a sample of N = 98 healthy volunteers who received either low-dose endotoxin (lipopolysaccharide) or vehicle (saline) intravenously. As measure of musculoskeletal pain sensitivity, pressure pain thresholds (PPTs) were assessed at baseline and 3 h post injection with a handheld algometer for the low back (erector spinae muscle), calf (gastrocnemius muscle), and shoulder region (deltoid muscle). Implementing multiple regression models, we tested the contribution of putative vulnerability factors on musculoskeletal hyperalgesia during systemic inflammation, including acute changes in pro-inflammatory cytokines, state anxiety and mood, as well as pre-existing symptoms of anxiety and depression. Endotoxin application led to significant increases in plasma cytokines, state anxiety, and negative mood, and significantly decreased PPTs for all muscle groups. Regression models revealed that greater M. erector spinae PPT changes were predicted by higher HADS-anxiety scores. Higher TNF-α concentration emerged as predictor for M. gastrocnemius PPT changes, and more pronounced TNF-α increase and higher HADS-anxiety were predictive for M. deltoideus PPTs. HADS scores emerged as predictor for a mean PPT score (computed across all body sites). Together, our results indicate that musculoskeletal hyperalgesia during systemic inflammation is related to pro-inflammatory cytokines, specifically TNF-α. Importantly, subclinical anxiety symptoms (even though in a low and normal range in this cohort of healthy volunteers) may contribute to inflammation-induced hyperalgesia, making individuals more vulnerable to the detrimental effects of systemic inflammation.

The relationship between the psychological stress of adolescents in school and the prevalence of chronic low back pain: a cross-sectional study in China

BACKGROUND

Accumulating evidence supports an association between an unhealthy mental state and low back pain (LBP). However, the degree of the association between mental health and chronic low back pain (CLBP) in the general population is poorly understood. The objective of this study was to analyze the incidence of CLBP in Chinese college students and to examine the association between students' unhealthy mental states and the prevalence of CLBP.

METHODS

This is a cross-sectional study. A total of 10,000 questionnaires were distributed in the second semester of the 2017-2018 academic year by the School of Medicine, Shanghai JiaoTong University. Eligible participants were students aged ≥ 18 years from randomly selected Chinese colleges. Participants completed a questionnaire survey that included items from the Symptom Checklist-90 (SCL-90) and items on demographic factors, LBP prevalence, quality of life at their university, study-related stress and interpersonal relationships. The evaluation of students' mental states in the survey was divided into two major parts: direct and indirect indicators. A multivariate logistic regression model was mainly used to explore the relationship between CLBP and the students' mental health.

RESULTS

There was a high incidence of CLBP in the college students. Multiple logistic regression analysis indicated that the risk of CLBP increased with increasing scores on the SCL-90, and a clinically unhealthy mental state (scores greater than 3) was significantly associated with CLBP (adjusted odds ratios for depression, anxiety, coercion, paranoia, and interpersonal sensitivity were 7.209, 6.593, 3.959, 4.465, and 4.283, respectively; p < 0.001). Participants who had poor living habits or uncomfortable campus lives and those who experienced heavy academic pressure also showed a higher positive association with CLBP compared with the full sample.

CONCLUSIONS

Unhealthy psychological conditions, which may be attributed to unsatisfying school lives, excessive learning pressure, and uncomfortable interpersonal relationships, represent a risk factor for CLBP in college students.

Sickness behavior is not all about the immune response: Possible roles of expectations and prediction errors in the worry of being sick

BACKGROUND

People react very differently when sick, and there are only poor correlations between the intensity of the immune response and sickness behavior. Yet, alternative predictors of the individual differences in sickness are under-investigated. Based on the predictive coding model of placebo responses, where health outcomes are function of bottom-up sensory information and top-down expectancies, we hypothesized that individual differences in behavioral changes during sickness could be explained by individual top-down expectancies and prediction errors.

METHODS

Twenty-two healthy participants were made sick by intravenously administering lipopolysaccharide (2 ng/kg body weight). Their expectations of becoming sick were assessed before the injection.

RESULTS

Participants having lower expectations of becoming sick before the injection reacted with more emotional distress (i.e., more negative affect and lower emotional arousal) than those with high expectations of becoming sick, despite having similar overall sickness behavior (i.e., a combined factor including fatigue, pain, nausea and social withdrawal). In keeping with a predictive coding model, the "prediction error signal", i.e., the discrepancy between the immune signal and sickness expectancy, predicted emotional distress (reduction in emotional arousal in particular).

CONCLUSION

The current findings suggest that the emotional component of sickness behavior is, at least partly, shaped by top-down expectations. Helping patients having a realistic expectation of symptoms during treatment of an illness may thus reduce aggravated emotional responses, and ultimately improve patients' quality of life and treatment compliance. REGISTRATION: "Endotoxin-induced Inflammatory and Behavioral Responses and Predictors of Individual Differences", https://clinicaltrials.gov/ct2/show/NCT02529592, registration number: NCT02529592.

Low-grade inflammation decreases emotion recognition - Evidence from the vaccination model of inflammation

The ability to adequately interpret the mental state of another person is key to complex human social interaction. Recent evidence suggests that this ability, considered a hallmark of 'theory of mind' (ToM), becomes impaired by inflammation. However, extant supportive empirical evidence is based on experiments that induce not only inflammation but also induce discomfort and sickness, factors that could also account for temporary social impairment. Hence, an experimental inflammation manipulation was applied that avoided this confound, isolating effects of inflammation and social interaction. Forty healthy male participants (mean age = 25, SD = 5 years) participated in this double-blind placebo-controlled crossover trial. Inflammation was induced using Salmonella Typhi vaccination (0.025 mg; Typhim Vi, Sanofi Pasteur, UK); saline-injection was used as a control. About 6 h 30 m after injection in each condition, participants completed the Reading the Mind in the Eyes Test (RMET), a validated test for assessing how well the mental states of others can be inferred through observation of the eyes region of the face. Vaccination induced systemic inflammation, elevating IL-6 by +419% (p < .001), without fever, sickness symptoms (e.g., nausea, light-headedness), or mood changes (all p's > .21). Importantly, compared to placebo, vaccination significantly reduced RMET accuracy (p < .05). RMET stimuli selected on valence (positive, negative, neutral) provided no evidence of a selective impact of treatment. By utilizing an inflammation-induction procedure that avoided concurrent sicknesses or symptoms in a double-blinded design, the present study provides further support for the hypothesis that immune activation impairs ToM. Such impairment may provide a mechanistic link explaining social-cognitive deficits in psychopathologies that exhibit low-grade inflammation, such as major depression.

Emotional State Can Affect Inflammatory Responses to Pain Among Rheumatoid Arthritis Patients: Preliminary Findings

In a novel pilot study, we investigated how emotional state is related to inflammatory responses to acute pain among women with rheumatoid arthritis. Nine women completed four 5-hour visits that varied only by manipulation of emotion (anger, sadness, happiness, vs. control); in each visit, acute pain was elicited, with blood draws at baseline, 10 minutes, 60 minutes, and 100 minutes post-pain. We examined the effects of within-subjects factors on circulating inflammatory biomarkers interleukin (IL)-6, IL-10, tumor necrosis factor-α, C-reactive protein, and cortisol. There was a main effect of state anger on IL-6, with higher reported anger associated with higher IL-6 across conditions. Further, there were several interactions between state emotion and condition. For example, when individuals reported higher state anger in the sadness condition compared to their own average, they showed higher levels of IL-6 and cortisol. Findings are discussed within a larger literature suggesting that mixed emotional states can contribute to psychological stress and inflammatory responses.

Decreased Pain and Improved Dynamic Knee Instability Mediate the Beneficial Effect of Wearing a Soft Knee Brace on Activity Limitations in Patients With Knee Osteoarthritis

OBJECTIVE

To evaluate whether improvement of proprioception, pain, or dynamic knee instability mediates the effect of wearing a soft knee brace on activity limitations in patients with knee osteoarthritis (OA).

METHODS

We conducted an analysis of data for 44 patients with knee OA who were enrolled in a laboratory-based trial evaluating the effect of wearing a commercially available soft knee brace. Activity limitations were assessed with the 10-meter walk test and the Get Up and Go test. Knee joint proprioception was assessed by an active joint position sense test; pain was assessed on a numeric rating scale (NRS) (range 0-10); pressure pain threshold (PPT) was assessed with a hand-held pressure algometer; dynamic knee instability was expressed by the perturbation response, i.e., a measure reflecting a deviation in mean knee varus-valgus angle after a controlled mechanical perturbation on a treadmill, with respect to level walking. Mediation analysis was conducted using the product of coefficients approach. Confidence intervals were calculated with a bootstrap procedure.

RESULTS

A decrease in pain (scored on an NRS) and a decrease in dynamic knee instability mediated the effect of wearing a soft knee brace on the reduction of activity limitations (P < 0.05), while changes in proprioception and PPT did not mediate this effect (P > 0.05).

CONCLUSION

This study shows that decreased pain and reduced dynamic knee instability are pathways by which wearing a soft knee brace decreases activity limitations in patients with knee OA.

Sex differences in how inflammation affects behavior: What we can learn from experimental inflammatory models in humans

Human models demonstrate that experimental activation of the innate immune system has profound effects on brain activation and behavior, inducing fatigue, worsened mood and pain sensitivity. It has been proposed that inflammation is a mechanism involved in the etiology and maintenance of depression, chronic pain and long-term fatigue. These diseases show a strong female overrepresentation, suggesting that a better understanding of sex differences in how inflammation drives behavior could help the development of individualized treatment interventions. For this purpose, we here review sex differences in studies using experimental inflammatory models to investigate changes in brain activity and behavior. We suggest a model in which inflammation accentuates sex differences in brain networks and pre-existing vulnerability factors. This effect could render women more vulnerable to the detrimental effects of immune-to-brain communication over time. We call for systematic and large scale investigations of vulnerability factors for women in the behavioral response to inflammation.

Associations between pain intensity and urge to smoke: Testing the role of negative affect and pain catastrophizing

BACKGROUND

Cigarette smokers are more likely to experience pain than nonsmokers, and experimental research indicates that pain is a potent motivator of smoking. Urge to smoke is a predictor of early relapse, yet associations between pain and urge to smoke have yet to be tested among daily smokers. This study aimed to conduct the first crosssectional test of associations between current pain intensity and urge to smoke, and to test the role of negative affect and pain catastrophizing in relations between pain intensity and urge to smoke.

METHODS

Participants (N = 229, 42.4% Female, 38.9% black/African American, Mcpd = 21.9) were recruited for a laboratory study of pain and smoking, and these data were collected at the baseline session. Data were analyzed using a series of regressions and conditional process models.

RESULTS

Current pain intensity was positively associated with urge to smoke, and urge to smoke for the relief of negative affect. There was an indirect association via state negative affect, such that pain intensity was positively associated with negative affect, which in turn was associated with greater urge to smoke. Further, positive associations between pain intensity and urge to smoke were only evident among smokers who endorsed low (vs high) levels of catastrophizing.

CONCLUSIONS

These findings contribute to an emerging literature indicating that pain and related constructs are relevant to the maintenance of tobacco smoking. Future research should examine how painrelevant cognitive-affective factors may influence associations between the experience of pain and motivation to smoke tobacco.

Negative Affectivity, Depression, and Resting Heart Rate Variability (HRV) as Possible Moderators of Endogenous Pain Modulation in Functional Somatic Syndromes

Background: Several studies have shown that patients with functional somatic syndromes (FSS) have, on average, deficient endogenous pain modulation (EPM), as well as elevated levels of negative affectivity (NA) and high comorbidity with depression and reduced resting heart rate variability (HRV) compared to healthy controls (HC). The goals of this study were (1) to replicate these findings and (2) to investigate the moderating role of NA, depression, and resting HRV in EPM efficiency within a patient group with fibromyalgia and/or chronic fatigue syndrome (CFS). Resting HRV was quantified as the root mean square of successive differences between inter-beat intervals (RMSSD) in rest, a vagally mediated time domain measure of HRV.

Methods: Seventy-eight patients with fibromyalgia and/or CFS and 33 HC completed a counter-irritation paradigm as a measure of EPM efficiency. Participants rated the painfulness of electrocutaneous stimuli (of individually calibrated intensity) on the ankle before (baseline phase), during (counter-irritation phase) and after (recovery phase) the application of a cold pain stimulus on the forearm. A larger reduction in pain in the counter-irritation phase compared to the baseline phase reflects a more efficient EPM.

Results: In contrast to our expectations, there was no difference between pain ratings in the baseline compared to counter-irritation phase for both patients and HC. Therefore, reliable conclusions on the moderating effect of NA, depression, and RMSSD could not be made. Surprisingly, patients reported more pain in the recovery compared to the counter-irritation and baseline phase, while HC did not. This latter effect was more pronounced in patients with comorbid depression, patients who rated the painfulness of the counter-irritation stimulus as high and patients who rated the painfulness of the electrocutaneous stimuli as low. We did not manage to successfully replicate the counter-irritation effect in HC or FSS patients. Therefore, no valid conclusions on the association between RMSSD, depression, NA and EPM efficiency can be drawn from this study. Possible reasons for the lack of the counter-irritation effect are discussed.

Effects of Patients' Affect on Adverse Procedural Events during Image-Guided Interventions

PURPOSE

To assess how a patient's affect on presentation relates to the likelihood of adverse events during their subsequent interventional image-guided procedures.

MATERIALS AND METHODS

A secondary analysis was performed of an existing dataset from a clinical trial with 230 patients who underwent percutaneous peripheral vascular and renal interventions and who had completed the positive affect (PA) negative affect (NA) schedule (PANAS) before their procedures. Summary PANAS scores were split over the median and used to classify the participants into those with high vs low PA and high vs low NA. Associations between affect and the absence or presence of adverse medical events were examined by two-sided Fisher exact tests.

RESULTS

Patients with high baseline NA were significantly more likely to have adverse events during their procedures than those with low baseline NA (18% vs 8%; P = .030). High baseline PA was not associated with a significantly higher frequency of subsequent adverse events compared with low PA (15% vs 9%; P = .23). Patients with high NA requested and received significantly more sedative and opioid agents than those with low NA (2.0 vs 1.0 units requested [P = .0009]; 3.0 vs 1.0 units received [P = .0004]). PA levels did not affect medication use.

CONCLUSIONS

High NA, but not PA, was associated with an increased likelihood of adverse events. Improving patients' NA before procedures seems a more suitable target than attempting to boost PA to improve the procedural experience.

Altered cytokine profile, pain sensitivity, and stress responsivity in mice with co-disruption of the developmental genes Neuregulin-1×DISC1

The complex genetic origins of many human disorders suggest that epistatic (gene×gene) interactions may contribute to a significant proportion of their heritability estimates and phenotypic heterogeneity. Simultaneous disruption of the developmental genes and schizophrenia risk factors Neuregulin-1 (NRG1) and Disrupted-in-schizophrenia 1 (DISC1) in mice has been shown to produce disease-relevant and domain-specific phenotypic profiles different from that observed following disruption of either gene alone. In the current study, anxiety and stress responsivity phenotypes in male and female mutant mice with simultaneous disruption of DISC1 and NRG1 were examined. NRG1×DISC1 mutant mice were generated and adult mice from each genotype were assessed for pain sensitivity (hot plate and tail flick tests), anxiety (light-dark box), and stress-induced hypothermia. Serum samples were assayed to measure circulating levels of pro-inflammatory cytokines. Mice with the NRG1 mutation, irrespective of DISC1 mutation, spent significantly more time in the light chamber, displayed increased core body temperature following acute stress, and decreased pain sensitivity. Basal serum levels of cytokines IL8, IL1β and IL10 were decreased in NRG1 mutants. Mutation of DISC1, in the absence of epistatic interaction with NRG1, was associated with increased serum levels of IL1β. Epistatic effects were evident for IL6, IL12 and TNFα. NRG1 mutation alters stress and pain responsivity, anxiety, and is associated with changes in basal cytokine levels. Epistasis resulting from synergistic NRG1 and DISC1 gene mutations altered pro-inflammatory cytokine levels relative to the effects of each of these genes individually, highlighting the importance of epistatic mechanisms in immune-related pathology.

Somatic Awareness and Tender Points in a Community Sample

Somatic awareness (SA) refers to heightened sensitivity to a variety of physical sensations and symptoms. Few attempts have been made to dissociate the relationship of SA and affective symptoms with pain outcomes. We used a validated measure of mood and anxiety symptoms that includes questions related to SA to predict the number of tender points found on physical examination in a large cross-sectional community sample (the Midlife in the United States [MIDUS] Biomarker study). General distress, positive affect, and SA, which were all significantly associated with tender point number in bivariate analyses, were used as predictors of the number of tender points in a multivariate negative binomial regression model. In this model a greater number of tender points was associated with higher levels of SA (P = .02) but not general distress (P = .13) or positive affect (P = .50). Follow-up mediation analyses indicated that the relationship between general distress and tender points was partially mediated by levels of SA. Our primary finding was that SA is strongly related to the number of tender points in a community sample. Mechanisms linking SA to the spatial distribution of pain sensitivity should be investigated further.

PERSPECTIVE

This article presents an analysis of 3 overlapping psychological constructs and their relationship to widespread pain sensitivity on palpation. The findings suggest that SA is most strongly related to the spatial distribution of pain sensitivity and that further assessing it may improve our understanding of the relationship between psychological factors and pain.

Well-being and immune response: a multi-system perspective

Whereas it is well-established that inflammation and other immune responses can change how we feel, most people are still surprised to hear that, conversely, well-being and its violations also affect our immune system. Here we show that those effects are highly adaptive and bear potential for both research and therapeutic applications. The studies discussed in this review demonstrate that immunity is tuned by ones emotions, personality, and social status as well as by other life style variables like sleep, nutrition, obesity, or exercise. We further provide a short excursion on the effects of stress and depression on immunity and discuss acute experimental endotoxemia as a model to study the effects of well-being on the innate immune response in humans.