Psychological stress in early life as a predisposing factor for the development of chronic pain: Clinical and preclinical evidence and neurobiological mechanisms

Early Life Stress and Major Depressive Disorder-An Update on Molecular Mechanisms and Synaptic Impairments

Early life stress (ELS), characterized as abuse, neglect, and abandonment, can cause several adverse consequences in the lives of affected individuals. ELS experiences can affect an individual's development in variable ways, persisting in the long term and promoting lasting impacts, considering that early exposure to stressors can be biologically incorporated, as prolonged stimulation of stress response systems affects the development of the brain structure and other body systems, increasing the risk of diseases associated with stress and cognitive impairment. This type of stress increases the risk of developing major depressive disorder (MDD) in a severe form that does not respond adequately to traditional antidepressant treatments. Several alterations are studied as mechanisms that relate ELS with MDD, such as epigenetic alterations, neurotransmitters, and neuronal signaling. This review discusses research that brings evidence about the ELS mechanisms involved in synaptic impairments and MDD. The processes involved in epigenetic changes and the HPA axis are highlighted, as well as changes in neurotransmitters and neuronal signaling mechanisms.

Trauma Prevalence and Its Association With Health-Related Quality of Life in Pregnant Persons with Opioid Use Disorder

OBJECTIVES

Trauma screening is recommended for pregnant persons with opioid use disorder (OUD), but there is limited literature on screening results from buprenorphine treatment. This study's objectives were to 1) describe the types, and severity, of traumatic events reported and 2) evaluate the associations between trauma and health-related quality of life (HRQoL).

METHODS

Baseline data from an ongoing trial were analyzed. Participants were 155 pregnant persons with OUD receiving, or enrolling in, buprenorphine treatment at one of 13 sites. The experience, and relative severity, of 14 high magnitude stressors were assessed with the trauma history screen. The Patient-Reported Outcomes Measurement Information System-29+2 was used to assess 8 HRQoL domains.

RESULTS

Traumatic stressors were reported by 91% of the sample (n = 155), with 54.8% reporting a lifetime persisting posttraumatic distress (PPD) event and 29.7% reporting a childhood PPD event. The most prevalent lifetime PPD event was sudden death of a close family/friend (25.8%); physical abuse was the most prevalent childhood PPD event (10.3%). Participants with lifetime PPD, relative to no PPD, reported significantly greater pain interference (P = 0.02). Participants with childhood PPD, relative to no PPD, had significantly worse HRQoL overall (P = 0.01), and worse pain intensity (P = 0.002), anxiety (P = 0.003), depression (P = 0.007), fatigue (P = 0.002), and pain interference (P < 0.001).

CONCLUSIONS

A majority of pregnant persons enrolled/enrolling in buprenorphine treatment reported persisting posttraumatic distress with sudden death of close family/friend being the most prevalent originating event; clinicians should consider the impact that the opioid-overdose epidemic may be having in increasing trauma exposure in patients with OUD.

Biobehavioral Predictors of Pain Intensity, Pain Interference, and Chronic Pain Episodes: A Prospective Cohort Study of African-American Adults

Racial disparities in pain experiences are well-established, with African-American (AA) adults reporting higher rates of daily pain, increased pain severity, and greater pain-related interference compared to non-Hispanic Whites. However, the biobehavioral factors that predict the transition to chronic pain among AA adults are not well understood. This prospective cohort study provided a unique opportunity to evaluate predictors of chronic pain onset among 130 AA adults (81 women), ages 18 to 44, who did not report chronic pain at their baseline assessment and subsequently completed follow-up assessments at 6- and 12-months. Outcome measures included pain intensity, pain-related interference, and chronic pain status. Comprehensive assessments of sociodemographic and biobehavioral factors were used to evaluate demographics, socioeconomic status, stress exposure, psychosocial factors, prolonged hypothalamic-pituitary-adrenal secretion, and quantitative sensory testing responses. At baseline, 30 adults (23.1%) reported a history of prior chronic pain. Over the 12-month follow-up period, 13 adults (10.0%) developed a new chronic pain episode, and 18 adults (13.8%) developed a recurrent chronic pain episode. Whereas socioeconomic status measures (ie, annual income, education) predicted changes in pain intensity over the follow-up period, quantitative sensory testing measures (ie, pain threshold, temporal summation of pain) predicted changes in pain interference. A history of chronic pain and higher depressive symptoms at baseline independently predicted the onset of a new chronic pain episode. The present findings highlight distinct subsets of biobehavioral factors that are differentially associated with trajectories of pain intensity, pain-related interference, and onset of chronic pain episodes in AA adults. PERSPECTIVE: This prospective study sought to advance understanding of biobehavioral factors that predicted pain outcomes over a 12-month follow-up period among AA adults without chronic pain at their initial assessment. Findings revealed distinct subsets of factors that were differentially associated with pain intensity, pain-related interference, and onset of chronic pain episodes.

Social Determinants and Consequences of Pain: Toward Multilevel, Intersectional, and Life Course Perspectives

Despite wide endorsement of a biopsychosocial framework for pain, social aspects of pain remain rarely addressed in the context of pain prevention and management. In this review, we aim to 1) examine the broad scope of social determinants and consequences of pain and their interactions across multiple levels of organization, and 2) provide a framework synthesizing existing concepts and potential areas for future work on social aspects of pain, drawing upon socioecological, intersectional, and life course approaches. Integrating interdisciplinary theory and evidence, we outline pathways through which multilevel social factors and pain may affect each other over time. We also provide a brief summary of intrapersonal aspects of pain, which are thought to operate at the interface between individuals and the social context. Progressing from micro- to macrolevel factors, we illustrate how social determinants of pain can directly or indirectly contribute to pain experiences, expression, risk, prognosis, and impact across populations. We consider 1) at the interpersonal level, the roles of social comparison, social relatedness, social support, social exclusion, empathy, and interpersonal conflict; 2) at the group or community level, the roles of intimacy groups, task groups, social categories, and loose associations; and 3) at the societal level, the roles of political, economic, and cultural systems, as well as their policies and practices. We present examples of multilevel consequences of pain across these levels and discuss opportunities to reduce the burden and inequities of pain by expanding multilevel social approaches in pain research and practice. PERSPECTIVE: Despite wide endorsement of a biopsychosocial framework for pain, social aspects of pain are often unclearly defined, hindering their use in pain prevention, management, and research. We summarize the scope of social aspects of pain and provide a framework synthesizing existing concepts and potential areas for future work.

Influence of Early-Life Stress on the Excitability of Dynorphin Neurons in the Adult Mouse Dorsal Horn

While early-life adversity has been associated with a higher risk of developing chronic pain in adulthood, the cellular and molecular mechanisms by which chronic stress during the neonatal period can persistently sensitize developing nociceptive circuits remain poorly understood. Here, we investigate the effects of early-life stress (ELS) on synaptic integration and intrinsic excitability in dynorphin-lineage (DYN) interneurons within the adult mouse superficial dorsal horn (SDH), which are important for inhibiting mechanical pain and itch. The administration of neonatal limited bedding between postnatal days (P)2 and P9 evoked sex-dependent effects on spontaneous glutamatergic signaling, as female SDH neurons exhibited a higher amplitude of miniature excitatory postsynaptic currents (mEPSCs) after ELS, while mEPSC frequency was reduced in DYN neurons of the male SDH. Furthermore, ELS decreased the frequency of miniature inhibitory postsynaptic currents selectively in female DYN neurons. As a result, ELS increased the balance of spontaneous excitation versus inhibition (E:I ratio) in mature DYN neurons of the female, but not male, SDH network. Nonetheless, ELS weakened the total primary afferent-evoked glutamatergic drive onto adult DYN neurons selectively in females, without modifying afferent-evoked inhibitory signaling onto the DYN population. Finally, ELS failed to significantly change the intrinsic membrane excitability of mature DYN neurons in either males or females. Collectively, these data suggest that ELS exerts a long-term influence on the properties of synaptic transmission onto DYN neurons within the adult SDH, which includes a reduction in the overall strength of sensory input onto this important subset of inhibitory interneurons. PERSPECTIVE: This study suggests that chronic stress during the neonatal period influences synaptic function within adult spinal nociceptive circuits in a sex-dependent manner. These findings yield new insight into the potential mechanisms by which early-life adversity might shape the maturation of pain pathways in the central nervous system (CNS).

Childhood trauma and the use of opioids and other prescription analgesics in adolescence and young adulthood: The HUNT Study

ABSTRACT

Opioid and nonopioid analgesics are commonly prescribed to young people to alleviate pain. Even short-term prescriptions increase the risk of persistent use and future misuse of potent analgesics, such as opioids. Childhood trauma exposure has been found to be related to pain conditions and to using more prescription analgesics. This large, prospective cohort study aimed to investigate the association of a broad range of childhood trauma exposures with prescription rates for opioid and nonopioid analgesics in adolescence and young adulthood. Self-reported data on childhood trauma exposures from adolescents (aged 13-19 years) who participated in the Young-HUNT3 Study (2006-2008, n = 8199) were linked to data from the Norwegian Prescription Database (NorPD, 2004-2021). We found that exposure to childhood trauma was consistently associated with higher prescription rates for opioids throughout adolescence and young adulthood. The highest incidence rate ratio (IRR) in adolescence was observed for sexual abuse (IRR 1.63, confidence interval [CI] 1.19-2.23). In young adulthood, the highest IRR was observed for physical violence (2.66, CI 2.27-3.12). The same overall pattern was observed for nonopioid analgesics. The more frequent prescriptions of opioid and nonopioid analgesics to participants exposed to childhood trauma suggests a higher symptom load of pain causing them to seek professional help with pain relief. Receiving potent analgesics is not without risk, and the likelihood of misuse may be elevated among trauma-exposed individuals. A trauma-informed approach to pain could be vital for guiding clinicians to the most effective and least harmful treatment for each patient.

Neuropathic pain, mood, and stress-related disorders: A literature review of comorbidity and co-pathogenesis

Neuropathic pain can be caused by multiple factors, and its prevalence can reach 10% of the global population. It is becoming increasingly evident that limited or short-lasting response to treatments for neuropathic pain is associated with psychological factors, which include psychiatric comorbidities known to affect quality of life. It is estimated that 60% of patients with neuropathic pain also experience depression, anxiety, and stress symptoms. Altered mood, including stress, can be a consequence of several painful conditions but can also favor pain chronicization when preexisting. Despite the apparent tight connection between clinical pain and mood/stress disorders, the exact physiological mechanisms remain unclear. This review aims to provide an overview of state-of-the-art research on the mechanisms of pain related to the pathophysiology of depression, anxiety, and stress disorders.

Overview: Chronic Pain and Cannabis-Based Medicines

Chronic pain is primarily conceptualized as a disease in its own right when it is associated with emotional distress and functional impairment. Pathophysiologically, dysfunction of the cortico-mesolimbic connectome is of major importance, with overlapping signals in the nociceptive and stress systems. The endocannabinoid system plays an important role in the central processing of nociceptive signals and regulates the central stress response. Clinically, there is moderate evidence that cannabis-based medicines (CBM) can contribute to a significant reduction in pain, especially the associated pain affect, and improvement in physical function and sleep quality in a proportion of patients with chronic pain. The analgesic effect appears to be largely independent of the cause of pain. In this context, CBM preferentially regulates stress-associated pain processing.

The feigned annoyance and frustration test to activate the sympathoadrenal medullary system

When perceived as threatening, social interactions have been shown to trigger the sympathoadrenal medullary system as well as the hypothalamic-pituitary-adrenal axis resulting in a physiologic stress response. The allostatic load placed on human health and physiology in the context of acute and chronic stress can have profound health consequences. The purpose of this study was to develop a protocol for a lab-based stress stimulus using social-evaluative threat. While several valid, stress-stimulating protocols exist, we sought to develop one that triggered a physiologic response, did not require significant lab resources, and could be completed in around 10 min. We included 53 participants (29 men and 24 women) and exposed them to a modified version of the Stroop Color-Word Interference Task during which the participants were made to feel they were performing the task poorly while the lead researcher feigned annoyance and frustration. After exposure to this Feigned Annoyance and Frustration (FAF) Test, both the men and women in this study demonstrated a statistically significant and clinically meaningful increase in subjective stress on the visual analog scale. Additionally, the men in this study demonstrated a statistically significant increase in heart rate and salivary α-amylase concentrations after exposure to the test. The women in this study did not demonstrate a statistically significant increase in the physiologic stress biomarkers. This protocol for the FAF Test shows promise to researchers with limited time and resources who are interested in experimentally activating the sympathoadrenal medullary system.

An examination of questioning methods and the influence of child maltreatment on paediatric pain assessments: Perspectives of healthcare providers

AIMS AND OBJECTIVES

Children with a history of maltreatment have underestimated and undertreated pain; however, it is unknown if healthcare providers consider maltreatment when assessing children's pain. The current study aimed to address this issue by investigating healthcare providers' pain assessment practices, and specifically, their consideration of child maltreatment.

METHOD

Healthcare providers (N = 100) completed a survey, asking them to reflect upon their pediatric pain assessment practices (e.g., methods and questions used to assess pain) through self-report and case vignette questions.

RESULTS

Participants who received continuing education about child maltreatment were more likely to consider maltreatment in several areas of their pediatric pain assessment practice, whereas participants who received continuing education about pediatric pain, were not. Participants were also more likely to report that they would consider maltreatment in vignette responses than in questions regarding their daily practice.

CONCLUSION

Findings indicate healthcare providers use multidimensional methods when assessing children's pain, although it is unclear when or how they use open-ended vs. option posing questions. Healthcare providers also tended to consider the effects of child maltreatment on children's ability to communicate their pain more so when the history of maltreatment was known to them.

Measuring interpersonal trauma: Development and validation of the German version of the victimization experience schedule (VES)

OBJECTIVE

Interpersonal victimization experiences (VEs) significantly affect mental and physical health, particularly in disorders associated with life-time adversities, like fibromyalgia syndrome (FMS) and major depressive disorder (MDD). However, assessing VEs comprehensively remains challenging due to limited tools that encompass sub-traumatic events, such as bullying or discrimination, and contextual dimensions. We aimed to address this gap by validating the Victimization Experience Schedule (VES) in German, examining its reliability, and assessing VEs in clinical populations with FMS and MDD.

METHODS

We investigated the relationship between VEs and clinical symptoms in individuals with FMS, MDD and healthy controls (N = 105) in a case-control study. We also analyzed correlations between different types of VEs and categories of early childhood abuse and posttraumatic-stress-disorder instruments. Additionally, we validated our findings in an independent sample of individuals with FMS (N = 97) from a clinical study.

RESULTS

We observed excellent inter-rater reliability (Kw = 0.90-0.99), and VEs assessed using the VES were in alignment with subcategories of early childhood abuse. The prevalence of VEs extended beyond the categories covered by traditional survey instruments and was higher in individuals with MDD (4.0 ± 2.6) and FMS (5.9 ± 3.1) compared to controls (1.5 ± 1.7). We consistently identified a significant association between the number of VEs, the associated subjective distress, and clinical scores. Furthermore, distinct correlation patterns between VEs and clinical outcomes emerged across different cohorts.

CONCLUSION

Our study emphasizes the VES's value in understanding VEs within MDD and FMS. These experiences span from traumatic to sub-traumatic and correlate with posttraumatic-stress and clinical symptoms, underscoring the VES's importance as an assessment tool.

Impact of Early-Life Adversity on Cannabis Use: Exploring the Mediating and Moderating Effects of Chronic Pain

Background: Although research suggests that early-life adversity (ELA) and cannabis use are linked, researchers have not established factors that mediate or modify this relationship. Identifying such factors could help in developing targeted interventions. We explored chronic pain as a potential mediator or moderator of this relationship. Methods: Using an online study, we collected cross-sectional data about ELA, cannabis use, and chronic pain to test whether ELA (adverse childhood experiences total score) is associated with cannabis use, and to examine pain as a potential mediator or moderator. Cannabis use was examined two ways: times used per day, and categorized as non-, some, or regular use. Chronic pain was measured as present/absent and as the number of painful body locations (0-8). Analyses used linear and multinomial regression. Results: ELA, chronic pain, and cannabis use were common among respondents. ELA was strongly associated with both measures of cannabis use. The number of painful body locations modestly mediated the association of ELA with cannabis use, reducing the magnitude of regression coefficients by about 1/7. The number of painful body locations modified the association between ELA and cannabis use (p≤0.006), while chronic pain presence/absence (a less-informative measure) had only a nonsignificant modification effect (p≥0.10). When either ELA or pain was high, the other was not associated with cannabis use; when either ELA or pain was low, more painful locations or higher ELA (respectively) was associated with more intense cannabis use. Conclusion: These exploratory findings suggest the importance of ELA and chronic pain as factors contributing to cannabis use, and of accounting for these factors in developing treatment and prevention strategies addressing cannabis use.

Environmental factors and their impact on chronic pain development and maintenance

It is more than recognized and accepted that the environment affects the physiological responses of all living things, from bacteria to superior vertebrates, constituting an important factor in the evolution of all species. Environmental influences range from natural processes such as sunlight, seasons of the year, and rest to complex processes like stress and other mood disorders, infections, and air pollution, being all of them influenced by how each creature deals with them. In this chapter, it will be discussed how some of the environmental elements affect directly or indirectly neuropathic pain, a type of chronic pain caused by a lesion or disease of the somatosensory nervous system. For that, it was considered the edge of knowledge in translational research, thus including data from human and experimental animals as well as the applicability of such findings.

Peripheral Endocannabinoid Components and Lipid Plasma Levels in Patients with Resistant Migraine and Co-Morbid Personality and Psychological Disorders: A Cross-Sectional Study

Resistant migraine characterizes those patients who have failed at least three classes of migraine prophylaxis. These difficult-to-treat patients are likely to be characterized by a high prevalence of psychological disturbances. A dysfunction of the endocannabinoid system (ECS), including alteration in the levels of endocannabinoid congeners, may underlie several psychiatric disorders and the pathogenesis of migraines. Here we explored whether the peripheral gene expression of major components of the ECS and the plasma levels of endocannabinoids and related lipids are associated with psychological disorders in resistant migraine. Fifty-one patients (age = 46.0 ± 11.7) with resistant migraine received a comprehensive psychological evaluation according to the DSM-5 criteria. Among the patients, 61% had personality disorders (PD) and 61% had mood disorders (MD). Several associations were found between these psychological disorders and peripheral ECS alterations. Lower plasma levels of palmitoiletanolamide (PEA) were found in the PD group compared with the non-PD group. The MD group was characterized by lower mRNA levels of diacylglycerol lipase α (DAGLα) and CB2 (cannabinoid-2) receptor. The results suggest the existence of peripheral dysfunction in some components of the ECS and an alteration in plasma levels of PEA in patients with resistant migraine and mood or personality disorders.

Increased Stress Is Associated With Severe Pain and Decrements in Cognitive Function in Patients Receiving Chemotherapy

OBJECTIVES

Purposes were to identify subgroups of adult oncology patients (n = 1342) with distinct joint profiles of worst pain and cognitive function (CF) and evaluate for differences in demographic and clinical characteristics, as well as the severity of three distinct types of stress, resilience, and coping.

DATA SOURCES

Measures of pain and CF were evaluated six times over two cycles of chemotherapy. The other measures of demographic and clinical characteristics, stress, resilience, and coping were completed at enrollment (ie, prior to the second or third cycle of chemotherapy).

RESULTS

Using latent profile analysis, four distinct profiles were identified (ie, no pain + moderate CF [27.6%], moderate pain + high CF [22.4%] moderate pain and moderate CF [32.4%, both moderate], severe pain and low CF [17.5%, both severe]). Both moderate and both severe classes reported higher global, cancer-specific, and cumulative life stress, lower levels of resilience, and greater use of disengagement coping strategies. The Both severe class had higher occurrence rates for a number of adverse childhood experiences (ie, family violence in childhood, physical abuse at <16 years, forced sex at <16 years). Risk factors associated with membership in the two worst profiles included: being female, having a lower annual income, having a higher comorbidity burden, and having a poorer functional status.

CONCLUSION

Findings suggest that 72.4% of the patients reported pain scores in the moderate to severe range and 77.6% reported low to moderate levels of CF. Clinicians need to assess for both symptoms and various types of stress on a routine basis.

C-Reactive Protein (CRP) is Associated With Chronic Pain Independently of Biopsychosocial Factors

Inflammation is linked with chronic pain but the extent to which this relationship is associated with biopsychosocial factors is not known. We investigated relationships between blood C-reactive protein (CRP) and regional chronic pain conditions adjusting for a large range and number of potential confounders. We performed cross-sectional analyses using the UK Biobank (N = 415,567) comparing CRP in people reporting any of 9 types of regional chronic pain with pain-free controls. Using logistic regression modelling, we explored relationships between CRP and the presence of chronic pain, with demographic, socioeconomic, psychological/lifestyle factors, and medical comorbidities as covariates. CRP was higher in chronic pain at any site compared with controls (Females: median [interquartile range] 1.60 mg/L [2.74] vs 1.17 mg/L [1.87], P < .001; Males: 1.44 mg/L [2.12] vs 1.15 mg/L [1.65], P < .001). In males, associations between CRP and all types of chronic pain were attenuated but remained significant after adjustment for biopsychosocial covariates (OR range 1.08-1.49, P ≤ .001). For females, adjusted associations between CRP and pain remained significant for most chronic pain types (OR range 1.07-1.34, P < .001) except for facial pain (OR 1.04, P = .17) and headache (OR 1.02, P = .07)-although these non-significant findings may reflect reduced sample size. The significant association between CRP and chronic pain after adjustment for key biopsychosocial confounders implicates an independent underlying biological mechanism of inflammation in chronic pain. The presence of yet unknown or unmeasured confounding factors cannot be ruled out. Our findings may inform better-targeted treatments for chronic pain. PERSPECTIVE: Using a large-scale dataset, this article investigates associations between chronic pain conditions and blood C-reactive protein (CRP), to evaluate the confounding effects of a range of biopsychosocial factors. CRP levels were higher in those with chronic pain versus controls after adjusting for confounders-suggesting a possible independent biological mechanism.

Emotion-Focused Psychodynamic Interview for People with Chronic Musculoskeletal Pain and Childhood Adversity: A Randomized Controlled Trial

Childhood adversity and emotional conflicts are associated with the presence and severity of chronic musculoskeletal pain (CMP), yet common treatments for CMP do not address such risk factors. We developed a single session, emotion-focused psychodynamic interview, based on Emotional Awareness and Expression Therapy and Intensive Short-term Psychodynamic Therapy, and we tested the interview's effects on pain-related outcomes and potential psychological mediators in a randomized, controlled trial. Adults (N = 91; ages 21-70, M = 44.64; 87.9% women) reporting CMP and at least 3 adverse childhood experiences completed measures at baseline and 6-week follow-up. Participants were randomized to immediate interview or waitlist control conditions. The 90-minute interview was conducted via videoconference, and the interviewer elicited disclosure of adversities and conflicts, linked these with pain, and encouraged the experience and expression of adaptive emotions. Analyses indicated that conditions did not differ significantly on change in pain severity; however, compared to control, the interview led to a significantly greater reduction in pain interference (P = .016, ηp2 = .05) and a similar trend for anxiety (P = .058, ηp2 = .04). The interview also significantly changed several potential mediators: pain-related anxiety (P = .008, ηp2 = .06), pain controllability (P = .016, ηp2 = .06), and psychological (P < .001, ηp2 = .15) and brain attributions (P = .022, ηp2 = .05) for pain. Participants viewed the interview as very valuable. We conclude that addressing childhood adversities and conflicts in a psychodynamic interview is beneficial for people with CMP. PERSPECTIVE: This study found that, compared to waitlist control, a 90-minute, remotely-administered, emotion-focused, psychodynamic interview improved pain interference, and anxiety among adults with chronic musculoskeletal pain and childhood adversity. Intensive emotional work can be done in a single session to the benefit of patients with chronic musculoskeletal pain.

The Stress Phenotyping Framework: A multidisciplinary biobehavioral approach for assessing and therapeutically targeting maladaptive stress physiology

Although dysregulated stress biology is becoming increasingly recognized as a key driver of lifelong disparities in chronic disease, we presently have no validated biomarkers of toxic stress physiology; no biological, behavioral, or cognitive treatments specifically focused on normalizing toxic stress processes; and no agreed-upon guidelines for treating stress in the clinic or evaluating the efficacy of interventions that seek to reduce toxic stress and improve human functioning. We address these critical issues by (a) systematically describing key systems and mechanisms that are dysregulated by stress; (b) summarizing indicators, biomarkers, and instruments for assessing stress response systems; and (c) highlighting therapeutic approaches that can be used to normalize stress-related biopsychosocial functioning. We also present a novel multidisciplinary Stress Phenotyping Framework that can bring stress researchers and clinicians one step closer to realizing the goal of using precision medicine-based approaches to prevent and treat stress-associated health problems.

Cognitive-Affective-Behavioral Pathways Linking Adversity and Discrimination to Daily Pain in African-American Adults

The tendency to ruminate, magnify, and experience helplessness in the face of pain - known as pain catastrophizing - is a strong predictor of pain outcomes and is associated with adversity. The ability to maintain functioning despite adversity - referred to as resilience - also influences pain outcomes. Understanding the extent to which pain catastrophizing and resilience influence relations between adversity and daily pain in healthy African-American adults could improve pain risk assessment and mitigate racial disparities in the transition from acute to chronic pain. This study included 160 African-American adults (98 women). Outcome measures included daily pain intensity (sensory, affective) and pain impact on daily function (pain interference). Adversity measures included childhood trauma exposure, family adversity, chronic burden from recent stressors, and ongoing perceived stress. A measure of lifetime racial discrimination was also included. Composite scores were created to capture early-life adversity (childhood trauma, family adversity) versus recent-life adversity (perceived stress, chronic burden). Increased pain catastrophizing was correlated with increased adversity (early and recent), racial discrimination, pain intensity, and pain interference. Decreased pain resilience was correlated with increased recent-life adversity (not early-life adversity or racial discrimination) and correlated with increased pain intensity (not pain-related interference). Bootstrapped multiple mediation models revealed that relationships between all adversity/discrimination and pain outcomes were mediated by pain catastrophizing. Pain resilience, however, was not a significant mediator in these models. These findings highlight opportunities for early interventions to reduce cognitive-affective-behavioral risk factors for persisting daily pain among African-American adults with greater adversity exposure by targeting pain catastrophizing.

Paraventricular Mast Cell-Derived Histamine Activates CRH Neurons to Mediate Adult Visceral Hypersensitivity Induced by Neonatal Maternal Separation

Neonatal maternal separation (NMS) is an early-life stress (ELS) that can result in adult visceral hypersensitivity, which is usually manifested as chronic visceral pain. Although mast cells and corticotropin-releasing hormone (CRH) neurons are involved in stress response, whether there is an interaction between mast cells and CRH neurons in hypothalamic paraventricular nucleus (PVN) during the ELS-induced visceral hypersensitivity remains elusive. Herein, we established an NMS model by separating neonatal mice from their mothers, and observed that these mice presented visceral hypersensitivity in adulthood, as indicated by elevated abdominal withdrawal reflex and lowered visceral pain threshold. The NMS-induced adult visceral hypersensitivity was accompanied by activation of mast cells and CRH neurons in PVN. Also, NMS increased the histamine content (an inflammatory mediator mainly released by mast cells) and histamine H2 receptor (H2R) expression of CRH neurons in PVN. Remarkably, intra-PVN administration with mast cell stabilizer attenuated the NMS-induced CRH neuronal activation and adult visceral pain, while histamine administration showed the opposite effects. Moreover, intra-PVN injection with H2R antagonist alleviated the NMS-induced CRH neuronal activation, PKA and CREB phosphorylation, and importantly, adult visceral pain. Together, our findings revealed a role of an interaction between paraventricular mast cells and CRH neurons in NMS-induced adult visceral hypersensitivity, thereby providing a perspective for the management of visceral pain.

Early life stress induces irritable bowel syndrome from childhood to adulthood in mice

Background

Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorder. Traditionally, early life stress (ELS) is predisposed to IBS in adult. However, whether ELS induces IBS in early life remains unclear.

Methods

Separated cohort studies were conducted in neonatal male pups of C57BL/6 mice by maternal separation (MS) model. MS and non-separation mice were scheduled to be evaluated for prime IBS-phenotypes, including visceral hypersensitivity, intestinal motility, intestinal permeability, and anxiety-like behavior. Ileal contents and fecal samples were collected and analyzed by 16S rRNA gene sequencing and bacterial community analyses. Subcellular structures of intestinal epithelial, such as epithelial tight junctions and mitochondria, were observed under transmission electron microscopy.

Results

MS induced visceral hypersensitivity and decreased total intestinal transit time from childhood to adulthood. In addition, MS induced intestinal hyperpermeability and anxiety-like behavior from adolescence to adulthood. Besides, MS affected intestinal microbial composition from childhood to adulthood. Moreover, MS disrupted intestinal mitochondrial structure from childhood to adulthood.

Conclusion

The study showed for the first time that MS induced IBS from early life to adulthood in mice. The disrupted intestinal mitochondrial structure and the significant dysbiosis of intestinal microbiota in early life may contribute to the initiation and progress of IBS from early life to adulthood.

Regional vs global physical therapy interventions to treat chronic pain in survivors of trauma: a randomized controlled trial

BACKGROUND

A history of traumatic life events is associated with chronic pain in later life. Physical therapists utilize a variety of methods to treat pain, however, they have struggled to find effective interventions to improve patient outcomes.

OBJECTIVE

To compare impairment-based, regional (REGION-PT) physical therapy (PT) to a global (GLOBAL-PT) model consisting of pain neuroscience education, graded motor imagery, and exercise for adults with chronic pain and history of trauma.

DESIGN

Randomized Controlled Trial.

METHODS

Adults ≥ 18 years of age with chronic pain and a history of ≥1 trauma identified through the Life Events Checklist received the allocated intervention once a week for six weeks. Treatment effects were assessed using linear mixed models.

RESULTS

Ninety-eight participants completed the trial. There were no difference in outcomes between groups. There were significant interactions between race and intervention. Both interventions were associated with improvements in pain interference for white participants, but non-white participants experienced improvement only with GLOBAL-PT. Regardless of allocation, participants improved in physical function, six of the PROMIS-29 domains, and in pain interference measures.

CONCLUSION

Both interventions are reasonable strategies for individuals with chronic pain and a history of trauma.

Early-life adversity increases morphine tolerance and persistent inflammatory hypersensitivity through upregulation of δ opioid receptors in mice

ABSTRACT

Exposure to severely stressful events during childhood is associated with poor health outcomes in later life, including chronic pain and substance use disorder. However, the mediators and mechanisms are unclear. We investigated the impact of a well-characterized mouse model of early-life adversity, fragmented maternal care (FC) between postnatal day 2 and 9, on nociception, inflammatory hypersensitivity, and responses to morphine. Male and female mice exposed to FC exhibited prolonged basal thermal withdrawal latencies and decreased mechanical sensitivity. In addition, morphine had reduced potency in mice exposed to FC and their development of tolerance to morphine was accelerated. Quantitative PCR analysis in several brain regions and the spinal cords of juvenile and adult mice revealed an impact of FC on the expression of genes encoding opioid peptide precursors and their receptors. These changes included enhanced abundance of δ opioid receptor transcript in the spinal cord. Acute inflammatory hypersensitivity (induced by hind paw administration of complete Freund's adjuvant) was unaffected by exposure to FC. However, after an initial recovery of mechanical hypersensitivity, there was a reappearance in mice exposed to FC by day 15, which was not seen in control mice. Changes in nociception, morphine responses, and hypersensitivity associated with FC were apparent in males and females but were absent from mice lacking δ receptors or β-arrestin2. These findings suggest that exposure to early-life adversity in mice enhances δ receptor expression leading to decreased basal sensitivity to noxious stimuli coupled with accelerated morphine tolerance and enhanced vulnerability to persistent inflammatory hypersensitivity.

A DNA methylation signature in the stress driver gene Fkbp5 indicates a neuropathic component in chronic pain

BACKGROUND

Epigenetic changes can bring insight into gene regulatory mechanisms associated with disease pathogenicity, including chronicity and increased vulnerability. To date, we are yet to identify genes sensitive to epigenetic regulation that contribute to the maintenance of chronic pain and with an epigenetic landscape indicative of the susceptibility to persistent pain. Such genes would provide a novel opportunity for better pain management, as their epigenetic profile could be targeted for the treatment of chronic pain or used as an indication of vulnerability for prevention strategies. Here, we investigated the epigenetic profile of the gene Fkbp5 for this potential, using targeted bisulphite sequencing in rodent pre-clinical models of chronic and latent hypersensitive states.

RESULTS

The Fkbp5 promoter DNA methylation (DNAm) signature in the CNS was significantly different between models of persistent pain, and there was a significant correlation between CNS and peripheral blood Fkbp5 DNAm, indicating that further exploration of Fkbp5 promoter DNAm as an indicator of chronic pain pathogenic origin is warranted. We also found that maternal separation, which promotes the persistency of inflammatory pain in adulthood, was accompanied by long-lasting reduction in Fkbp5 DNAm, suggesting that Fkbp5 DNAm profile may indicate the increased vulnerability to chronic pain in individuals exposed to trauma in early life.

CONCLUSIONS

Overall, our data demonstrate that the Fkbp5 promoter DNAm landscape brings novel insight into the differing pathogenic origins of chronic pain, may be able to stratify patients and predict the susceptibility to chronic pain.

Killing pain? A prospective population-based study on trauma exposure in childhood as predictor for frequent use of over-the-counter analgesics in young adulthood. The HUNT study

Frequent and increasing use of over-the-counter analgesics (OTCA) is a public health concern. Pain conditions and psychological distress are related to frequent OTCA use, and as exposure to potentially traumatic events (PTE) in childhood appears to increase risk of experiencing such symptoms, we aimed to assess childhood PTEs and related symptoms in adolescence as predictors for frequent OTCA use in young adulthood. Prospective population survey data were used (n = 2947, 59.1% female, 10-13 years follow-up). Exposure to PTEs, symptoms of post-traumatic stress, anxiety and depression, musculoskeletal pain and headache were assessed in adolescence (13-19 years). Use of OTCA was assessed in young adulthood (22-32 years) and use of OTCA to treat musculoskeletal pain and headache served as separate outcomes in ordinal logistic regression analyses. Overall, exposure to childhood PTEs, particularly direct interpersonal violence, was significantly and consistently related to more frequent use of OTCA to treat musculoskeletal pain and headaches in young adulthood. Adjusting for psychological symptoms and pain attenuated associations, indicating that these symptoms are of importance for the relationship between traumatic events and OTCA use. These findings emphasize the need to address symptomatology and underlying causes at an early age.

Effects of Corticosterone on the Excitability of Glutamatergic and GABAergic Neurons of the Adolescent Mouse Superficial Dorsal Horn

Stress evokes age-dependent effects on pain sensitivity and commonly occurs during adolescence. However, the mechanisms linking adolescent stress and pain remain poorly understood, in part due to a lack of information regarding how stress hormones modulate the function of nociceptive circuits in the adolescent CNS. Here we investigate the short- and long-term effects of corticosterone (CORT) on the excitability of GABAergic and presumed glutamatergic neurons of the spinal superficial dorsal horn (SDH) in Gad1-GFP mice at postnatal days (P)21-P34. In situ hybridization revealed that glutamatergic SDH neurons expressed significantly higher mRNA levels of both glucocorticoid receptors (GR) and mineralocorticoid receptors (MR) compared to adjacent GABAergic neurons. The incubation of spinal cord slices with CORT (90 min) evoked select long-term changes in spontaneous synaptic transmission across both cell types in a sex-dependent manner, without altering the intrinsic firing of either Gad1-GFP+ or GFP- neurons. Meanwhile, the acute bath application of CORT significantly decreased the frequency and amplitude of miniature excitatory postsynaptic currents (mEPSCs), as well as the frequency of miniature inhibitory postsynaptic currents (mIPSCs), in both cell types leading to a net reduction in the balance of spontaneous excitation vs. inhibition (E:I ratio). This CORT-induced reduction in the E:I ratio was not prevented by selective antagonists of either GR (mifepristone) or MR (eplerenone), although eplerenone blocked the effect on mEPSC amplitude. Collectively, these data suggest that corticosterone modulates synaptic function within the adolescent SDH which could influence the overall excitability and output of the spinal nociceptive network.

Current Evidence for Biological Biomarkers and Mechanisms Underlying Acute to Chronic Pain Transition across the Pediatric Age Spectrum

Chronic pain is highly prevalent in the pediatric population. Many factors are involved in the transition from acute to chronic pain. Currently, there are conceptual models proposed, but they lack a mechanistically sound integrated theory considering the stages of child development. Objective biomarkers are critically needed for the diagnosis, risk stratification, and prognosis of the pathological stages of pain chronification. In this article, we summarize the current evidence on mechanisms and biomarkers of acute to chronic pain transitions in infants and children through the developmental lens. The goal is to identify gaps and outline future directions for basic and clinical research toward a developmentally informed theory of pain chronification in the pediatric population. At the outset, the importance of objective biomarkers for chronification of pain in children is outlined, followed by a summary of the current evidence on the mechanisms of acute to chronic pain transition in adults, in order to contrast with the developmental mechanisms of pain chronification in the pediatric population. Evidence is presented to show that chronic pain may have its origin from insults early in life, which prime the child for the development of chronic pain in later life. Furthermore, available genetic, epigenetic, psychophysical, electrophysiological, neuroimaging, neuroimmune, and sex mechanisms are described in infants and older children. In conclusion, future directions are discussed with a focus on research gaps, translational and clinical implications. Utilization of developmental mechanisms framework to inform clinical decision-making and strategies for prevention and management of acute to chronic pain transitions in children, is highlighted.

The mediating effect of allostatic load on the association between life course socioeconomic disadvantage and chronic pain: a prospective finding from the National Survey of Midlife Development in the United States

Background

Socioeconomic disadvantages (SEDs) are associated with chronic pain (CP) and allostatic load (AL). Few prospective population-based studies have examined the relationship between life course SED, CP interference, and CP widespreadness, and there is no prospective population-based study on whether AL mediates the association between SED and CP.

Objective

In this study, we investigated whether the prospective effect of SED on CP at Midlife in the United States (MIDUS) 3 is consistent with the accumulation of risk model and social mobility model, using the National Survey of MIDUS (n = 593). To prepare for the mediation analysis, we tested (1) whether SED would be prospectively associated with AL in the MIDUS 2 biomarker project, (2) whether AL would be prospectively associated with CP, and (3) whether childhood, as a critical period, moderated the association between AL and CP. In addition, the mediating effect of AL on the association between SED and CP was examined.

Method

SED was measured using cumulative scores and disadvantage trajectories derived from latent class trajectory modeling (LCTM). After multiple imputations, analyses were conducted using multinomial logistic regression for CP and negative binomial regression for AL, respectively. Finally, mediation analyses and moderated mediation analyses were performed.

Results

LCTM identified three SED trajectories, namely, constant low, high to low, and medium to high. The results showed that proximal cumulative SED was associated with high-interference CP. Furthermore, compared with the group with constant low SED, the group with medium-to-high SED was significantly associated with high-interference pain and experienced pain in at least three different sites. Cumulative SED and deteriorating SED trajectories were associated with higher AL, consistent with previous studies. Furthermore, childhood SED moderated the effect of AL on CP widespreadness and unexpectedly demonstrated a protective effect, while other associations between AL and CP were not significant. Subsequent mediation analysis did not yield statistically significant evidence.

Conclusions

People who experienced more recent SED or increasing disadvantage throughout their lives were more likely to suffer from CP, and this association was not mediated by physiological system dysregulation caused by chronic stress. Therefore, measures to alleviate AL may not be effective in protecting socioeconomically disadvantaged populations from CP.

Adverse childhood experiences and lifelong health

With the advent of the sustainable development goals, the field of global child health has shifted its focus from reducing mortality to improving health, nutrition and development outcomes - often measured as human capital. A growing knowledge of the biology of development and neuroscience has highlighted the importance of adverse environmental exposures, collectively termed adverse childhood experiences (ACEs) on health outcomes. ACEs are associated with short-term, medium-term and long-term negative consequences for health and development and their effects may be multiplicative, especially during critical periods of sensitivity and developmental plasticity. Some of these effects are compounded by emerging global threats such as climate change, conflict and population displacement. In this Review, we discuss the key mechanisms linking ACEs to health outcomes and consider promising strategies to prevent and mitigate their effects, highlighting evidence from programs in low-income and middle-income countries. Finally, we emphasize the need for early recognition of ACEs and delivery of packages of interventions spanning key sectors such as health, education, women's empowerment and social protection.

The association between adverse childhood experiences, self-silencing behaviours and symptoms in women with fibromyalgia

Poor adult health has consistently been associated with Adverse Childhood Experiences (ACEs). The process is not fully understood but is likely to involve a complex interaction of biological and psychosocial factors. Early life stress can affect the developing brain resulting in long-term hyper-responses to stress and raised inflammatory biomarkers. Women with fibromyalgia syndrome (FMS) frequently report ACEs and also self-sacrificial behaviours whereby they repress their own needs and emotions to preserve personal relationships. This behavioural profile (termed self-silencing) may develop following ACEs but has not previously been considered in the context of FMS. This study examined whether self-silencing mediates the link between ACEs and FMS symptoms. Women with (N = 539) and without (N = 184) an FMS diagnosis completed measures of Silencing-the-Self, health symptoms and ACEs. Number of ACEs and symptom levels were significantly associated in both groups. One aspect of self-silencing, care and self-sacrifice (putting others needs before your own) mediated the association between ACEs and symptoms in the FMS group only. Externalised self-perception (judging oneself according to perceived external standards) was negatively associated with symptoms but presented no mediating effects. Results present preliminary new information to explain the association between ACEs and FMS. Recognition of the factors which underlie symptomology is important in understanding the condition and supporting patients.

The Foundations for Chronic Low Back Pain Management may Start in Early Life. Exploring the Role of Caregiver Parental Leave on Future Low Back Pain in the Offspring

Chronic low back pain is difficult to treat and despite increased spending on health services, clinical outcomes for people with low back pain have not improved. Innovative, large scale initiatives seem necessary to stem the cost of low back pain. Psychological health contributes to the development and persistence of chronic low back pain and psychological interventions are important in the management of low back pain. Given the contribution of psychological health to low back pain development and management, it raises the question; can we support psychological health in later life by bolstering emotional development in early life, and reduce the burden of this common condition? Positive early life experiences, including those induced by extended paid parental leave, could bolster emotional development and support the psychological health necessary to manage low back pain in later life. We present the current state of evidence demonstrating the potential value of increasing support for parent-child relationships in early life to reduce the burden of low back pain in future generations. The current evidence is limited to cross-sectional associations, but strong preclinical data clearly shows the potential negative impacts of maternal separation on rodent pup health that compels consideration in human populations. PERSPECTIVE: The benefits stemming from enhanced child development include stable emotional foundations, possibly improving psychological health and low back pain management in the future. This perspective raises questions for future studies - within the context of low back pain, what ingredients bolster stable psychological health? And are these ingredients influenced by parental leave?

Everybody Hurts: Intersecting and Colliding Epidemics and the Need for Integrated Behavioral Treatment of Chronic Pain and Substance Use

Chronic pain and substance use disorders are both common, debilitating, and often persist over the longer term. On their own, each represents a significant health problem, with estimates indicating a substantial proportion of the adult population has chronic pain or a substance use disorder (SUD), and their co-occurrence is increasing. Chronic pain and SUD are also both often invisible, stigmatized disorders and persons with both regularly have difficulty accessing evidence-based treatments, particularly those that offer coordinated and integrated treatment for both conditions. But there is hope. Research is unraveling the mechanisms of chronic pain and substance use, as well as their co-occurrence, integrated behavioral treatment options based on acceptance- and mindfulness-based approaches are increasingly being developed and tested, government agencies are devoting more funds and resources to increase research on chronic pain and SUD, and there have been growing efforts in training, dissemination, and implementation of evidence-based treatments. At the very heart of the matter, though, is to recognize that everybody hurts sometimes, and treatments must empower people to life effectively with these experiences of being human.

The effect of adverse childhood experiences on chronic pain and major depression in adulthood: a systematic review and meta-analysis

BACKGROUND

Adverse childhood experiences have been linked to increased multimorbidity, with physical and mental health consequences throughout life. Chronic pain is often associated with mood disorders, such as major depressive disorder (MDD); both have been linked to adverse childhood experiences. It is unclear how the effect of adverse childhood experiences on neural processing impacts on vulnerability to chronic pain, MDD, or both, and whether there are shared mechanisms. We aimed to assess evidence for central neural changes associated with adverse childhood experiences in subjects with chronic pain, MDD, or both using systematic review and meta-analysis.

METHODS

Electronic databases were systematically searched for neuroimaging studies of adverse childhood experiences, with chronic pain, MDD, or both. Two independent reviewers screened title, abstracts, and full text, and assessed quality. After extraction of neuroimaging data, activation likelihood estimate meta-analysis was performed to identify significant brain regions associated with these comorbidities.

RESULTS

Forty-nine of 2414 studies were eligible, of which 43 investigated adverse childhood experiences and MDD and six investigated adverse childhood experiences and chronic pain. None investigated adverse childhood experiences, chronic pain, and MDD together. Functional and structural brain abnormalities were identified in the superior frontal, lingual gyrus, hippocampus, insula, putamen, superior temporal, inferior temporal gyrus, and anterior cerebellum in patients with MDD exposed to adverse childhood experiences. In addition, brain function abnormalities were identified for patients with MDD or chronic pain and exposure to adverse childhood experiences in the cingulate gyrus, inferior parietal lobule, and precuneus in task-based functional MRI studies.

CONCLUSIONS

We found that adverse childhood experiences exposure can result in different functional and structural brain alterations in adults with MDD or chronic pain compared with those without adverse childhood experiences.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO CRD42021233989.

Neurophysiological and Psychosocial Mechanisms of Fibromyalgia: A Comprehensive Review and Call for An Integrative Model

Research into the neurobiological and psychosocial mechanisms involved in fibromyalgia has progressed remarkably in recent years. Despite this, current accounts of fibromyalgia fail to capture the complex, dynamic, and mutual crosstalk between neurophysiological and psychosocial domains. We conducted a comprehensive review of the existing literature in order to: a) synthesize current knowledge on fibromyalgia; b) explore and highlight multi-level links and pathways between different systems; and c) build bridges connecting disparate perspectives. An extensive panel of international experts in neurophysiological and psychosocial aspects of fibromyalgia discussed the collected evidence and progressively refined and conceptualized its interpretation. This work constitutes an essential step towards the development of a model capable of integrating the main factors implicated in fibromyalgia into a single, unified construct which appears indispensable to foster the understanding, assessment, and intervention for fibromyalgia.

Traumatic Events, Posttraumatic Stress Disorder, and Central Sensitization in Chronic Pain Patients of a German University Outpatient Pain Clinic

OBJECTIVE

Posttraumatic stress disorder (PTSD) and traumatic life events are often coupled to chronic pain, possibly linked by central sensitization. We wanted to assess the prevalence of traumatic events and PTSD in chronic pain patients of a German university hospital outpatient pain clinic. Moreover, we evaluated the extent of indicators and co-occurring traits of central sensitization in comorbid patients.

METHODS

We retrospectively divided 914 chronic pain patients into four groups depending on their trauma severity: no trauma, accidental trauma, interpersonal trauma, and PTSD. We collected electronic pain drawings focusing on pain area and widespreadness, as well as information about pain intensity, sleep impairment, disability, stress, anxiety, depression, and somatization. Differences between groups were calculated using Kruskal-Wallis with post-hoc Mann-Whitney tests.

RESULTS

Of 914 patients, 231 (25%) had no trauma, 210 (23%) had accidental traumas, 283 (31%) had interpersonal traumas, 99 (11%) had PTSD, and 91 (10%) could not be classified. We observed statistically significant differences between groups in pain area and widespreadness, as well as maximal pain, sleep impairment, disability, stress, anxiety, depression, and somatization. The severity of symptoms increased with trauma severity.

CONCLUSIONS

Traumatic life events and PTSD are frequent in chronic pain patients. The increased pain area and widespreadness, as well as the increased negative impact on co-occurring traits of sensory sensitivity (anxiety, depression, somatization), are compatible with central sensitization in comorbid patients. Therefore, a heightened awareness of the comorbidity between traumatic experiences and chronic pain is recommended.

Child maltreatment and pediatric pain: A survey of healthcare professionals' pain knowledge and pain management techniques

Children who have been maltreated are at an increased risk of having their pain under-recognized and undertreated by healthcare professionals, and thus, are more susceptible to adverse outcomes associated with undertreated pain. This study's aims were to examine: (1) if healthcare professionals' pediatric pain knowledge is associated with their pain assessment methods, (2) if maltreatment-specific pain knowledge is associated with consideration of child maltreatment when deciding on a pain management strategy, and (3) if pediatric pain knowledge would relate to maltreatment-specific pain knowledge. A sample (N = 108) of healthcare professionals responded to a survey designed to examine their current knowledge and utilization of pediatric pain assessment and management with emphasis on the effects of child maltreatment. Findings revealed healthcare professionals' knowledge of pediatric pain is independent of their pain assessment and management practices. However, general pain knowledge was associated with maltreatment-specific pain knowledge and generally, healthcare professionals were knowledgeable of child maltreatment's impact on pediatric pain. Participants who considered a history of maltreatment were also more likely to employ sensitive questioning strategies when asking children about their pain.

Early life stress, depression and epigenetics

Different factors are essential in increasing the vulnerability to psychiatric disorders, such as genetics. Among these factors, early life stress (ELS), including sexual, physical, emotional abuse, and emotional and physical neglect, enhances the odds of having menial conditions throughout life. Exhaustive research has shown that ELS leads to physiological changes, such as alteration in the HPA axis. During the most critical development period (childhood and adolescence), these changes increase the risk of having child-onset psychiatric disorders. Furthermore, research has suggested a relationship between early life stress and depression, particularly more prolonged episodes of depression with treatment-resistant outcomes. Molecular studies indicate that, in general, the hereditary character of psychiatric disorders is polygenic, multifactorial and highly complex, with innumerable low-effect genetic variants interacting with each other. However, whether there are independent effects among subtypes of ELS remains unclear. This article provides an overview of the interplay of epigenetics, the HPA axis, early life stress and the development of depression. Advances in our knowledge of epigenetics in the context of early life stress and depression provide a new understanding of the genetic influence on psychopathology. Furthermore, they could lead to identifying new targets for clinical intervention.

A Shared Genetic Signature for Common Chronic Pain Conditions and its Impact on Biopsychosocial Traits

The multiple comorbidities & dimensions of chronic pain present a formidable challenge in disentangling its aetiology. Here, we performed genome-wide association studies of 8 chronic pain types using UK Biobank data (N =4,037-79,089 cases; N = 239,125 controls), followed by bivariate linkage disequilibrium-score regression and latent causal variable analyses to determine (respectively) their genetic correlations and genetic causal proportion (GCP) parameters with 1,492 other complex traits. We report evidence of a shared genetic signature across chronic pain types as their genetic correlations and GCP directions were broadly consistent across an array of biopsychosocial traits. Across 5,942 significant genetic correlations, 570 trait pairs could be explained by a causal association (|GCP| >0.6; 5% false discovery rate), including 82 traits affected by pain while 410 contributed to an increased risk of chronic pain (cf. 78 with a decreased risk) such as certain somatic pathologies (eg, musculoskeletal), psychiatric traits (eg, depression), socioeconomic factors (eg, occupation) and medical comorbidities (eg, cardiovascular disease). This data-driven phenome-wide association analysis has demonstrated a novel and efficient strategy for identifying genetically supported risk & protective traits to enhance the design of interventional trials targeting underlying causal factors and accelerate the development of more effective treatments with broader clinical utility. PERSPECTIVE: Through large-scale phenome-wide association analyses of >1,400 biopsychosocial traits, this article provides evidence for a shared genetic signature across 8 common chronic pain types. It lays the foundation for further translational studies focused on identifying causal genetic variants and pathophysiological pathways to develop novel diagnostic & therapeutic technologies and strategies.

Life-course socioeconomic circumstances in acute, chronic and disabling pain among young employees: a double suffering

BACKGROUND

Pain is known to be socioeconomically patterned and associated with disability. However, knowledge is scarce concerning life-course socioeconomic circumstances and pain among young adults. Our aim was to examine the associations of childhood and current socioeconomic circumstances with acute pain and chronic pain with low and high disability levels among young Finnish municipal employees.

METHODS

We analysed questionnaire data retrieved from the Young Helsinki Health Study (n=4683) covering 18-39-year-old employees of the City of Helsinki, Finland. We included multiple indicators of childhood and current socioeconomic circumstances and examined their associations with acute pain and with chronic pain with low and high disability levels. The level of chronic pain-related disability was assessed by the chronic pain grade questionnaire. Multinomial logistic regression analyses were conducted with stepwise adjustments for sociodemographic, socioeconomic and health-related covariates.

RESULTS

Childhood and current socioeconomic disadvantage were associated with acute and chronic pain, particularly with chronic pain with high disability level. The strongest associations after adjustments for covariates remained between chronic pain with high disability level and low educational level (odds ratio (OR) 3.38, 95% confidence interval (CI) 2.18-5.24), manual occupation (OR 3.75, 95% CI 1.92-7.34) and experiencing frequent economic difficulties (OR 3.07, 95% CI 2.00-4.70).

CONCLUSIONS

Pain is a common complaint that contributes to disability among young employees, particularly the most socioeconomically vulnerable. There is a socioeconomic gradient in both pain chronicity and the level of chronic pain-related disability. Life-course socioeconomic factors should be considered in pain-preventing strategies and in clinical practice.

The association between adverse childhood experiences and peripartal pain experience

ABSTRACT

Adverse childhood experiences (ACEs) are associated with altered ongoing and evoked pain experiences, which have scarcely been studied for the peripartum period. We aimed to investigate how ACEs affect pain experience in pregnancy and labor. For this noninterventional trial with a short-term follow-up, pregnant women were divided into a trauma group (TG) with ACEs (n = 84) and a control group (CG) without ACEs (n = 107) according to the Childhood Trauma Questionnaire. Pain experience in pregnancy and labor was recorded by self-report and the German Pain Perception Scale. Pain sensitivity prepartum and postpartum was assessed by Quantitative Sensory Testing and a paradigm of conditioned pain modulation (CPM), using pressure pain thresholds (PPTs) and a cold pressor test. The TG showed higher affective and sensory scores for back pain and a more than doubled prevalence of preexisting back pain. Pelvic pain differences were nonsignificant. The TG also exhibited increased affective scores (1.71 ± 0.15 vs 1.33 ± 0.11), but not sensory scores for labor pain during spontaneous delivery. There were no group differences in prepartum pain sensitivity. While PPTs increased through delivery in the CG (clinical CPM), and this PPT change was positively correlated with the experimental CPM (r = 0.55), this was not the case in the TG. The association of ACEs with increased peripartal pain affect and heightened risk for preexisting back pain suggest that such women deserve special care. The dissociation of impaired clinical CPM in women with ACEs and normal prepartum experimental CPM implies at least partly different mechanisms of these 2 manifestations of endogenous pain controls.

Reconsidering Fordyce's classic article, "Pain and suffering: what is the unit?" to help make our model of chronic pain truly biopsychosocial

ABSTRACT

The biopsychosocial model (BPS) of chronic pain aspires to be comprehensive, incorporating psychological and social factors omitted from biomedical models. Although psychosocial factors are viewed as highly influential in understanding behavioral and psychological responses to pain, these factors are usually viewed as modifiers of biological causes of the experience of pain itself, rather than as equal contributors to pain. To further advance the BPS model, we re-examine a classic 1994 article by Wilbert "Bill" Fordyce, "Pain and suffering: what is the unit?" In this article, Fordyce suggested that pain-related disability and suffering should be viewed as "transdermal," as having causes both inside and outside the body. We consider Fordyce's article theoretically important because this concept allows us to more fully break free of the medical model of chronic pain than customary formulations of the BPS model. It makes it possible to place psychological and social factors on an equal footing with biological ones in explaining pain itself and to remove distinctions between pain mechanisms and pain meanings. The brain's salience network now offers a platform on which diverse influences on pain experience-from nociception to multisensory indicators of safety or danger-can be integrated, bridging the gap between impersonal nociceptive mechanisms and personal meanings. We also argue that Fordyce's article is practically important because this concept expands the BPS model beyond the bounds of the clinical encounter, opening the door to the full range of social, psychological, and biological interventions, empowering patients and nonmedical providers to tackle chronic pain.

A high-fat high-sugar diet and adversity early in life modulate pain outcomes at the behavioural and molecular level in adolescent rats: The role of sex

Given that adolescence is a significant period of brain plasticity and development, early life factors have the potential to alter long term outcomes. For instance, adversities such as consumption of a high-fat high-sugar (HFHS) diet and adverse childhood experiences (ACEs; e.g., neglect), and their resulting inflammation and microglial activation can influence pain outcomes by priming the neuroimmune system to overrespond to stressors. Chronic pain is highly prevalent amongst the adolescent population, with the prevalence and manifestation being sexually dimorphic. Although clinical studies show that females are twice as likely to report pain problems compared to males, the majority of pre-clinical work uses male rodents. Therefore, our aim was to examine the effects of sex, a HFHS diet, and an ACE on chronic pain outcomes following a stressor in adolescence. Rat dams were randomly assigned to a Standard or HFHS diet, with pups maintained on their respective diets then randomly allocated to a No Stress or ACE paradigm, and a Sham or Injury condition as a stressor. Results showed that early life adversities increased nociceptive sensitivity, inflammation, and microglial activation systemically and within the brain. Behaviourally, pain outcomes were more prominent in females, however the neuroimmune response was exacerbated in males. These results demonstrate the sexual dimorphism of chronic pain outcomes following early life adversities and provide insight into the mechanisms driving these changes, which will inform more targeted and effective treatment strategies for youth living with chronic pain.

Stress-induced changes in nociceptive responding post-surgery in preclinical rodent models

Chronic post-surgical pain affects up to 85% of individuals depending on the type of surgery, the extent of inflammation, tissue and/or nerve damage. Pre-surgical stress is associated with greater pain intensity, prolonged recovery and is one of the main risk factors for the development of chronic post-surgical pain. Clinically valid animal models provide an important means of examining the mechanisms underlying the effects of stress on post-surgical pain and identifying potential novel therapeutic targets. This review discusses the current data from preclinical animal studies examining the effect of stress on post-surgical pain, the potential underlying mechanisms and gaps in the knowledge that require further investigation.

Association between short-term exposure to extreme humidity and painful diabetic neuropathy: a case-crossover analysis

Painful diabetic neuropathy (PDN) is a common complication of diabetes mellitus, which reduces the quality of life. However, the association between PDN and environmental factors, especially ambient humidity, remains unclear. Therefore, this study investigated the impact of extreme humidity events on PDN. Data on PDN-related hospital admissions to two tertiary hospitals in Hefei, China (2014-2019) were obtained. A distributed lag non-linear model with a case-crossover design was used to quantitatively estimate the effects of ambient humidity on PDN, and the results were stratified by sex and age. The 1st, 10th, 90th, and 99th percentiles of relative humidity (RHU) were defined as extreme humidity, and the average relative humidity (74.94%) was set as the reference value. Non-linear exposure-response curves between the RHU and PDN cases were obtained. Extreme humidity (92%) had a significant effect on PDN with a relative risk (RR) of 1.13 (95% confidence interval (CI): 1.01-1.26) on a particular day, which increased with the RHU (RR: 1.21, 95% CI: 1.02-1.45 at 98% extreme humidity). Stratification analysis showed that women (RR: 1.38, 95% CI: 1.07-1.77) and patients aged < 65 years (RR: 1.26, 95% CI: 1.01-1.57) were highly susceptible to this effect on the same day. The results suggest that extreme humidity is a crucial trigger for PDN onset in diabetes patients. Furthermore, the effects vary with sex and age. This study provides detailed evidence of the adverse effects of extreme weather on diabetes patients.

Prevalence, severity and impact of chronic pain among a representative cross-sectional study of New Zealand high school students

AIM

To report the prevalence of self-reported chronic pain and severity among young people in New Zealand and explore the relationships between pain and mental health, substance use, socialisation and school engagement.

METHODS

Prevalence of self-reported chronic pain frequency and severity are reported from an anonymous, representative cross-sectional self-administered health and well-being questionnaire by students aged 12-18 years in New Zealand. Multivariable models exploring chronic pain and mental health, substance use, socialisation and school engagement are reported controlling for age, sex, ethnicity, socio-economic status, disability and history of sexual abuse.

RESULTS

Overall, 22.8% (95% confidence interval (CI) 21.2-24.5) of young people reported chronic pain for 6 months or more, with 3.2% (95% CI 3.1-4.5) reporting severe pain weekly or more often. Females and rural adolescents were more likely to report chronic and severe pain. Asian youth reported less pain than other ethnic groups. Increased severity of pain was associated more with poorer daily functioning and socialising than with frequency of pain. Severe pain occurring weekly or more often was more common among students who had a disability (2.3% 95% CI 1.8-2.7 vs. 9.8%, 95% CI 7.2-12.5) or a history of sexual abuse (2.4% 95% 1.9-2.9 vs. 8.5%, 95% CI 6.3-10.5). Those reporting chronic pain had higher proportions of self-reported significant depressive symptoms, lower well-being, lower school engagement and lower access to health care, particularly for those reporting higher levels of intensity and frequency of pain.

CONCLUSIONS

Chronic pain is common in adolescent populations, and has a significant association with decreased daily functioning, socialising, school engagement and mental well-being. Adolescents with chronic pain report significant unmet health-care needs.

Emotion regulation and the salience network: a hypothetical integrative model of fibromyalgia

Fibromyalgia is characterized by widespread pain, fatigue, sleep disturbances and other symptoms, and has a substantial socioeconomic impact. Current biomedical and psychosocial treatments are unsatisfactory for many patients, and treatment progress has been hindered by the lack of a clear understanding of the pathogenesis of fibromyalgia. We present here a model of fibromyalgia that integrates current psychosocial and neurophysiological observations. We propose that an imbalance in emotion regulation, reflected by an overactive 'threat' system and underactive 'soothing' system, might keep the 'salience network' (also known as the midcingulo-insular network) in continuous alert mode, and this hyperactivation, in conjunction with other mechanisms, contributes to fibromyalgia. This proposed integrative model, which we term the Fibromyalgia: Imbalance of Threat and Soothing Systems (FITSS) model, should be viewed as a working hypothesis with limited supporting evidence available. We hope, however, that this model will shed new light on existing psychosocial and biological observations, and inspire future research to address the many gaps in our knowledge about fibromyalgia, ultimately stimulating the development of novel therapeutic interventions.

Research progress on the mechanism of chronic neuropathic pain

Chronic neuropathic pain (CNP) refers to pain that lasts for more than three months due to a disease or an injury to the somatosensory nervous system. The incidence of CNP has been increasing in the world, causing it to become a global concern and patients often experience spontaneous pain, hyperalgesia, abnormal pain or even abnormal sensation as some of its main symptoms. In addition to serious pain and poor physical health, CNP also negatively affects patients' mental health, thus impacting the overall quality of their lives. The pathogenesis of CNP is not clear, but some studies have proved that central sensitization, peripheral sensitization, neuroinflammation, dysfunction in descending nociceptive modulatory systems, oxidative stress reaction, activation of glial cells and psychological factors play an important role in the occurrence and development of CNP. In this context, this article summarizes the current research progress on the mechanism of CNP to provide a basis for further research in preventing and treating the disease.

The path to healthy ageing in China: a Peking University-Lancet Commission

Around the world, populations are ageing at a faster pace than in the past and this demographic transition will have impacts on all aspects of societies. In May 2020, the UN General Assembly declared 2021–2030 the Decade of Healthy Ageing, highlighting the importance for policymakers across the world to focus policy on improving the lives of older people, both today and in the future. While rapid population ageing poses challenges, China’s rapid economic growth over the last forty years has created space for policy to assist older persons and families in their efforts to improve health and well-being at older ages. As China is home to 1/5 of the world’s older people, China is often held up as an example for other middle-income countries. This Commission Report aims to help readers to understand the process of healthy ageing in China as a means of drawing lessons from the China experience. In addition, with the purpose of informing the ongoing policy dialogue within China, the Commission Report highlights the policy challenges on the horizon and draws lessons from international experience.