The interaction between stress and chronic pain through the lens of threat learning

Obesity Hurts: The Why and How of Integrating Weight Reduction With Chronic Pain Management

Amongst adults with chronic pain, overweight and obesity are highly prevalent. The association between chronic pain and overweight is driven by several explanations, including increased biomechanical load, changes in the gut microbiome, and low-grade (neuro)inflammation. Moreover, the link between overweight, obesity and chronic pain can best be considered from a lifestyle perspective. Since conservative treatment for chronic pain is often limited to short-term and small effects, addressing important comorbidities within a lifestyle approach could be the next step towards precision medicine for these patients. Indeed, evidence shows that combining weight reduction with conservative pain management is more effective to reduce pain and disability, compared to either intervention alone. This perspective article aims to update the reader with the current understanding of the possible explanatory mechanisms behind the interaction between overweight/obesity and chronic pain in an adult population. Second, this paper applies this knowledge to clinical practice, including assessment and conservative treatment of overweight/obesity in adults with chronic pain. Henceforth, clinical recommendations and guidelines are provided based on available scientific evidence and the authors' clinical expertise.

IMPACT

This paper will guide clinicians in the implementation of weight reduction programs within pain management.

Targeting the stress response in pediatric pain: current evidence for psychosocial intervention and avenues for future investigation

Nonpharmacological treatments for chronic pain in youth have been identified as first-line treatments over and above medication. Therapies such as cognitive-behavioral therapy and mindfulness-based stress reduction have shown good efficacy in reducing the psychological correlates (eg, anxiety, depression, and stress) and social or behavioral sequelae (eg, limited physical activity and lack of school engagement) associated with pediatric chronic pain. However, minimal research has examined the physiological mechanism(s) of action for these interventions. A recent review (Cunningham, et al., 2019) emphasized the need for objective (ie, physiological) assessment of treatment response in pediatric pain populations. The current review adds to this literature by identifying the physiological stress response as a particular target of interest in interventions for pediatric pain. Research indicates that youth with chronic pain report high rates of psychological stress, posttraumatic stress symptoms, and exposure to adverse childhood experiences (abuse/neglect, etc). In addition, a host of research has shown strong parallels between the neurobiology of pain processing and the neurobiology of stress exposure in both youth and adults. Interventions such as narrative or exposure therapy (eg, trauma-focused cognitive-behavioral therapy) and mindfulness-based or meditation-based therapies have shown particular promise in alleviating the neurobiological impact that stress and pain can have on the body, including reduction in allostatic load and altered connectivity in multiple brain regions. However, no study to date has specifically looked at these factors in the context of pediatric pain treatment. Future research should further explore these constructs to optimize prevention in and treatment of these vulnerable populations.

The Impact of the First Wave of the COVID-19 Pandemic on Patients' Perceptions of Chronic Pain

Purpose

On 10 March 2020, Greece entered an increasingly restrictive 42-day lockdown, in order to contain the first wave of the COVID-19 pandemic. All scheduled appointments and activities of the pain clinics around the country were postponed indefinitely. The aim of this prospective study was to assess the perceived impact of the first wave of the pandemic on pain, quality of life, and access to treatment, during the first austere lockdown in Greece.

Patients and Methods

In this cross-sectional study, 101 patients suffering from chronic pain completed a structured questionnaire. Levels of depression, anxiety, stress, personal wellbeing, optimism and personality traits were also evaluated, using the Depression, Anxiety and Stress Scale (DASS42), the Ten Item Personality Index (TIPI), the Life Orientation Test-Revised (GrLOT-R) and the Personal Wellbeing Index (PWI).

Results

Despite the dramatic decrease in health care visitations before, during and after the imposed lockdown, most patients did not feel that access to pain physicians and medication was significantly affected. Higher levels of stress, anxiety, depression, neuroticism, openness to experience and general satisfaction with life seemed to be important determinant factors in how patients experienced their level, intensity and duration of pain, quality of life and response to medication.

Conclusion

The effects of the lockdown had a more severe impact on patients than the pandemic itself. For most, the level of their pain was not affected by the pandemic and was affected only slightly by the lockdown. Quality of life, however, was affected formost participants. Both the necessity and the complications of introducing the use of telemedicine to Greek chronic pain patients became evident during the study.

Pain relief reverses hippocampal abnormalities in trigeminal neuralgia

Chronic pain patients frequently report memory and concentration difficulties. Objective testing in this population points to poor performance on memory and cognitive tests, and increased comorbid anxiety and depression. Recent evidence has suggested convergence between chronic pain and memory deficits onto the hippocampus. The hippocampus consists of heterogenous subfields involved in memory consolidation, behavior regulation, and stress modulation. Despite significant studies outlining hippocampal changes in human and chronic pain animal models, the effect of pain relief on hippocampal abnormalities remains unknown. Trigeminal neuralgia (TN) is a chronic neuropathic pain disorder which is highly amenable to surgical interventions, providing a unique opportunity to investigate the effect of pain relief. This study investigates the effect of pain relief on hippocampal subfields in TN. Anatomical MR images of 61 TN patients were examined before and 6 months after surgery. Treatment responders (n=47) reported 95% pain relief, whereas non-responders (n=14) reported 40% change in pain on average. At baseline, patients had smaller hippocampal volumes, compared to controls. After surgery, responders' hippocampal volumes normalized, largely driven by CA2/3, CA4 and dentate gyrus, which are involved in memory consolidation and neurogenesis. We propose that hippocampal atrophy in TN is pain-driven and successful treatment normalizes such abnormalities.

The Long-Term Effects of Neonatal Inflammatory Pain on Cognitive Function and Stress Hormones Depend on the Heterogeneity of the Adolescent Period of Development in Male and Female Rats

Exposure to stress at an early age programs the HPA axis which can lead to cognitive deficits in adults. However, it is not known whether these deficits emerge in adulthood or are expressed earlier in life. The aims of the study were to investigate (1) the immediate effects of early injury-induced stress in one-day-old (P1) and repeated stress on at P1 and P2 rat pups on plasma corticosterone levels; and (2) examine the subsequent long-term effects of this early stress on spatial learning and memory, and stress reactivity in early P26-34 and late P45-53 adolescent male and female rats. Intra-plantar injection of formalin induced prolonged and elevated levels of corticosterone in pups and impaired spatial learning and short- and long-term memory in late adolescent males and long-term memory in early adolescent females. There were sex differences in late adolescence in both learning and short-term memory. Performance on the long-term memory task was better than that on the short-term memory task for all early adolescent male and female control and stressed animals. Short-term memory was better in the late age control rats of both sexes and for formalin treated females as compared with the early age rats. These results are consistent with an impaired function of structures involved in memory (the hippocampus, amygdala, prefrontal cortex) after newborn pain. However, activation of the HPA axis by neonatal pain did not directly correlate with spatial learning and memory outcomes and the consequences of neonatal pain remain are likely multi-determined.

How environmental enrichment balances out neuroinflammation in chronic pain and comorbid depression and anxiety disorders

Depression and anxiety commonly occur in chronic pain states and the coexistence of these diseases worsens outcomes for both disorders and may reduce treatment adherence and response. Despite the advances in the knowledge of chronic pain mechanisms, pharmacological treatment is still unsatisfactory. Research based on exposure to environmental enrichment is currently under investigation and seems to offer a promising low-cost strategy with no side effects. In this review, we discuss the role of inflammation as a major biological substrate and aetiological factor of chronic pain and depression/anxiety and report a collection of preclinical evidence of the effects and mechanisms of environmental enrichment. As microglia participates in the development of both conditions, we also discuss microglia as a potential target underlying the beneficial actions of environmental enrichment in chronic pain and comorbid depression/anxiety. We also discuss how alternative interventions under clinical guidelines, such as environmental enrichment, may improve treatment compliance and patient outcomes.

A Conditional Process Model to Explain Somatization During Coronavirus Disease 2019 Epidemic: The Interaction Among Resilience, Perceived Stress, and Sex

Background

More than 15% of Chinese respondents reported somatic symptoms in the last week of January 2020. Promoting resilience is a possible target in crisis intervention that can alleviate somatization.

Objectives

This study aims to investigate the relationship between resilience and somatization, as well as the underlying possible mediating and moderating mechanism, in a large sample of Chinese participants receiving a crisis intervention during the coronavirus disease 2019 epidemic.

Methods

Participants were invited online to complete demographic information and questionnaires. The Symptom Checklist-90 somatization subscale, 10-item Connor–Davidson resilience scale, and 10-item Perceived Stress Scale were measured.

Results

A total of 2,557 participants were included. Spearman correlation analysis revealed that lower resilience was associated with more somatic symptoms (p < 0.001). The conditional process model was proved (indirect effect = −0.01, 95% confidence interval = [−0.015, −0.002]). The interaction effects between perceived stress and sex predicted somatization (b = 0.05, p = 0.006).

Conclusion

Resilience is a key predictor of somatization. The mediating effects of perceived stress between resilience and somatization work in the context of sex difference. Sex-specific intervention by enhancing resilience is of implication for alleviating somatization during the coronavirus disease 2019 epidemic.

Associative learning and extinction of conditioned threat predictors across sensory modalities

The formation and persistence of negative pain-related expectations by classical conditioning remain incompletely understood. We elucidated behavioural and neural correlates involved in the acquisition and extinction of negative expectations towards different threats across sensory modalities. In two complementary functional magnetic resonance imaging studies in healthy humans, differential conditioning paradigms combined interoceptive visceral pain with somatic pain (study 1) and aversive tone (study 2) as exteroceptive threats. Conditioned responses to interoceptive threat predictors were enhanced in both studies, consistently involving the insula and cingulate cortex. Interoceptive threats had a greater impact on extinction efficacy, resulting in disruption of ongoing extinction (study 1), and selective resurgence of interoceptive CS-US associations after complete extinction (study 2). In the face of multiple threats, we preferentially learn, store, and remember interoceptive danger signals. As key mediators of nocebo effects, conditioned responses may be particularly relevant to clinical conditions involving disturbed interoception and chronic visceral pain.

Psychosocial stress and musculoskeletal pain among senior workers from nine occupational groups: Cross-sectional findings from the SeniorWorkingLife study

INTRODUCTION

Maintaining good health with advancing age is increasingly important as most European countries experience an increase in retirement age. In order to decrease the risk of premature departure from the workforce, identifying groups at increased risk of musculoskeletal pain and psychosocial stress is essential in designing workplace policies. Therefore, the aim of this study was to investigate the relationship between occupational groups differing in terms of physical demands and skill requirement, and the outcomes of stress and pain.

METHODS

This cross-sectional study reports associations of nine different occupational groups with stress and pain among 11 474 senior workers; stratified by occupational group and based on the International Standard Classification of Occupations (ISCO). A large-scale questionnaire survey was dispatched to Danish workers; drawn as a probability sample and merged with national registers. Representative estimates were produced using logistic regression controlling for various confounders, combined with model-assisted weights.

RESULTS

The prevalence of daily pain and high stress among occupational groups ranged between 20.0%-50.5% and 3.9%-10.0%, respectively. Compared with occupations characterised by being mostly sedentary (ISCO group 1-4), those with primarily physical demanding work (ISCO group 5-9) had higher odds of daily pain (OR 1.53, 95% CI 1.37 to 1.70) and a tendency towards higher stress scores (OR 1.20, 95% CI 0.98 to 1.46). Lastly, female workers experience increased odds of daily pain (OR 1.50, 95% CI 1.35 to 1.66) and high stress (OR 1.56, 95% CI 1.29 to 1.89) compared with male workers.

CONCLUSIONS

Occupational settings characterised by mainly physical work and low skill requirements are more likely to experience daily pain compared with those entailing mainly sedentary work. Likewise, in this sample of senior workers, women are more likely to experience pain and stress. These results highlights the need for improving occupation-specific and sex-specific guidelines in the prevention of musculoskeletal pain and psychological stress in workplaces.

TRIAL REGISTRATION NUMBER

ClinicalTrials identifier: NCT03634410.

What Does CATS Have to Do With Cancer? The Cognitive Activation Theory of Stress (CATS) Forms the SURGE Model of Chronic Post-surgical Pain in Women With Breast Cancer

Chronic post-surgical pain (CPSP) represents a highly prevalent and significant clinical problem. Both major and minor surgeries entail risks of developing CPSP, and cancer-related surgery is no exception. As an example, more than 40% of women undergoing breast cancer surgery struggle with CPSP years after surgery. While we do not fully understand the pathophysiology of CPSP, we know it is multifaceted with biological, social, and psychological factors contributing. The aim of this review is to advocate for the role of response outcome expectancies in the development of CPSP following breast cancer surgery. We propose the Cognitive Activation Theory of Stress (CATS) as an applicable theoretical framework detailing the potential role of cortisol regulation, inflammation, and inflammatory-induced sickness behavior in CPSP. Drawing on learning theory and activation theory, CATS offers psychobiological explanations for the relationship between stress and health, where acquired expectancies are crucial in determining the stress response and health outcomes. Based on existing knowledge about risk factors for CPSP, and in line with the CATS position, we propose the SURGEry outcome expectancy (SURGE) model of CPSP. According to SURGE, expectancies impact stress physiology, inflammation, and fear-based learning influencing the development and persistence of CPSP. SURGE further proposes that generalized response outcome expectancies drive adaptive or maladaptive stress responses in the time around surgery, where coping dampens the stress response, while helplessness and hopelessness sustains it. A sustained stress response may contribute to central sensitization, alterations in functional brain networks and excessive fear-based learning. This sets the stage for a prolonged state of inflammatory-induced sickness behavior - potentially driving and maintaining CPSP. Finally, as psychological factors are modifiable, robust and potent predictors of CPSP, we suggest hypnosis as an effective intervention strategy targeting response outcome expectancies. We here argue that presurgical clinical hypnosis has the potential of preventing CPSP in women with breast cancer.

Subclinical post-traumatic stress symptomology and brain structure in youth with chronic headaches

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ACEs and PTSS did not significantly differ between patients and healthy controls.

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Patients demonstrated greater corticolimbic connectivity compared to controls.

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Greater PTSS and less corticolimbic connectivity increased headache frequency.

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Less corticolimbic connectivity may indicate greater disease progression.

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Patients may be more vulnerable to the effects of PTSS compared to controls.

Background/aims

Post-traumatic stress symptoms (PTSS) and chronic pain often co-occur at high rates in youth. PTSS may alter brain structure thereby contributing to headache chronicity. This study examined whether PTSS and altered limbic circuitry were associated with headache frequency in youth.

Methods

Thirty youth aged 10–18 years with chronic headaches and 30 age- and sex-matched controls underwent a 3T MRI scan. Volumes of the hippocampus and amygdala were obtained from T1-weighted images. Mean fractional anisotropy (FA, an index of white matter structure) axial and radial diffusivity values of the cingulum and uncinate fasciculus were extracted from diffusion-weighted images. Youth reported on their headaches daily, for one-month, and self-reported pubertal status, emotion regulation, adverse childhood experiences (ACEs) and PTSS using validated measures. Volumes of the hippocampus and amygdala and diffusivity values of the cingulum and uncinate were compared between patients and controls. Hierarchical linear regressions were used to examine the association between PTSS, subcortical volumes and/or diffusivity values and headache frequency.

Results

Mean FA values of the cingulum were higher in patients compared to controls (P = 0.02, Cohen’s d = 0.69). Greater PTSS (P = 0.04), smaller amygdala volumes (P = 0.01) and lower FA of the cingulum (P = 0.04) were associated with greater headache frequency, after accounting for age, puberty, pain duration, emotion regulation, and ACEs (Adjusted R² ≥ 0.15). Headache frequency was associated with increases in radial diffusivity (P = 0.002, Adjusted R² = 0.59), as opposed to axial diffusivity (n.s.).

Conclusions

PTSS, smaller amygdalar volume, and poorer cingulum structural connectivity were associated with headache frequency in youth, and may underlie headache chronicity.

Prevalence and correlates of somatization in anxious individuals in a Chinese online crisis intervention during COVID-19 epidemic

BACKGROUND

Somatization is a common comorbidity in anxious people. From January 31 to February 2, 2020, a high prevalence of moderate to severe anxiety was detected due to COVID-19 outbreak. The purpose of this study was to investigate the prevalence and correlates of somatization among Chinese participants with anxiety receiving online crisis interventions from Feb 14 to Mar 29 during the COVID-19 epidemic.

METHODS

A total of 1134 participants who participated in online crisis interventions completed the Generalized Anxiety Disorder-7 (GAD-7) scale and the Symptom Checklist-90 (SCL-90) and demographic questions online. Somatization was defined as the average score of each item ≥ 2 in SCL-90 somatization subscale. Moderate to severe anxiety was defined as a score ≥ 10 in the GAD-7 scale.

RESULTS

Among all participants, 8.0% reported moderate to severe anxiety and 7.4% reported somatization. After March 1, the prevalence of anxiety with or without somatization did not significantly change (both p > 0.05), while the prevalence of somatization increased significantly (p < 0.01). Logistic regression analysis indicated that somatization was associated with chronic disease history (with an odds ratio of 4.80) and female gender (with an odds ratio of 0.33).

CONCLUSIONS

Our findings suggest that the history of chronic diseases is associated with somatization in individuals with anxiety, indicating some stress-related mechanisms. Chinese men in crisis intervention need more attention because they are more likely to report anxiety comorbid somatization.

Neuropeptide and cytokine regulation of pain in the context of substance use disorders

Substance use disorders (SUDs) are frequently accompanied by affective symptoms that promote negative reinforcement mechanisms contributing to SUD maintenance or progression. Despite their widespread use as analgesics, chronic or excessive exposure to alcohol, opioids, and nicotine produces heightened nociceptive sensitivity, termed hyperalgesia. This review focuses on the contributions of neuropeptide (CRF, melanocortin, opioid peptide) and cytokine (IL-1β, TNF-α, chemokine) systems in the development and maintenance of substance-induced hyperalgesia. Few effective therapies exist for either chronic pain or SUD, and the common interaction of these disease states likely complicates their effective treatment. Here we highlight promising new discoveries as well as identify gaps in research that could lead to more effective and even simultaneous treatment of SUDs and co-morbid hyperalgesia symptoms.

Stressful experiences in youth: "Set-up" for diminished resilience to chronic pain

Chronic pain in youth is common, with prevalence rates in some reports exceeding 50%. Given the plasticity of brain systems in youth and their general level of activity, the underlying processes relating to the evolution of chronic pain may be different from that observed in adults. One aspect that affects brain development is childhood stress. Preliminary research indicates that maladaptive responses to stressful events that induce biological and psychological inability to adapt may be related to pain chronicity in youth. This relationship is particularly notable given the high rates of exposure to stressful events in pediatric pain populations. A review of the literature was performed in the areas of biological, cognitive, psychological and social processes associated with chronic pain and psychological stress and trauma in youth and adult populations. The current review presents a theoretical framework, adapted from McEwen's model (1998) on stress and allostatic load, which aims to outline the potential connection between exposure to stressful events and pediatric chronic pain. Avenues for future investigation are also identified.