Epidemiology of pain and relation to psychiatric disorders

Impaired neuronal macroautophagy in the prelimbic cortex contributes to comorbid anxiety-like behaviors in rats with chronic neuropathic pain

A large proportion of patients with chronic pain experience co-morbid anxiety. The medial prefrontal cortex (mPFC) is proposed to underlie this comorbidity, but the molecular and neuronal mechanisms are not fully understood. Here, we reported that impaired neuronal macroautophagy in the prelimbic cortical (PrL) subregion of the mPFC paralleled the occurrence of anxiety-like behaviors in rats with chronic spared nerve injury (SNI). Intriguingly, such macroautophagy impairment was mainly observed in a FOS/c-Fos+ neuronal subpopulation in the PrL. Chemogenetic inactivation of this comorbid anxiety-related neuronal ensemble relieved pain-induced anxiety-like behaviors. Rescuing macroautophagy impairment in this neuronal ensemble relieved chronic pain-associated anxiety and mechanical allodynia and restored synaptic homeostasis at the molecular level. By contrast, artificial disruption of macroautophagy induced early-onset co-morbid anxiety in neuropathic rats, but not general anxiety in normal rats. Taken together, our work identifies causal linkage between PrL neuronal macroautophagy dysfunction and comorbid anxiety in neuropathic pain and provides novel insights into the role of PrL by differentiating its contribution in pain-induced comorbid anxiety from its modulation over general anxiety-like behaviors.Abbreviation: AAV: adeno-associated viruses; ACC: anterior cingulate cortex; ATG5: autophagy related 5; ATG7: autophagy related 7; ATG12: autophagy related 12; CAMK2/CaMKII: calcium/calmodulin-dependent protein kinase II; CNO: clozapine-N-oxide; CQ: chloroquine; DIA: data independent acquisition; DIO: double floxed inverse orf; DLG4/PSD-95: discs large MAGUK scaffold protein 4; Dox: doxycycline; GABA: γ-aminobutyric acid; GFP: green fluorescent protein; GO: gene ontology; Gi: inhibitory guanine nucleotide-binding proteins; HsCHRM4/M4D: human cholinergic receptor muscarinic 4; HsSYN: human synapsin; KEGG: Kyoto encyclopedia of genes and genomes; LAMP1: lysosomal-associated membrane protein 1; LC3-II: PE conjugated microtubule-associated protein 1 light chain3; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; mPFC: medial prefrontal cortex; P2A: 2A self-cleaving peptide; PPI: protein-protein interaction networks; PrL: prelimbic cortex; RBFOX3/NeuN: RNA binding protein, fox-1 homolog (C. elegans) 3; rtTA: reverse tetracycline-transactivator; SDS-PAGE: sodium dodecylsulfate-polyacrylamide gel electrophoresis; SHANK3: SH3 and multiple ankyrin repeat domains 3; SLC1A1/EAAC1: solute carrier family 1 (neuronal/epithelial high affinity glutamate transporter, systemXag), member 1; SNAP23: synaptosomal-associated protein 23; SNI:spared nerve injury; SQSTM1/p62: sequestosome 1; SYT3: synaptotagmin 3; TRE: tetracycline-responsive element; TRE3G: third-generation tetracycline-responsive element.

Investigating the association of opioid prescription with the incidence of psychiatric disorders: nationwide cohort study in South Korea

BACKGROUND

The relationship between opioid use and the incidence of psychiatric disorders remains unidentified.

AIMS

This study examined the association between the incidence of psychiatric disorders and opioid use.

METHOD

Data for this population-based cohort study were obtained from the National Health Insurance Service of South Korea. The study included all adult patients who received opioids in 2016. The control group comprised individuals who did not receive opioids in 2016, and were selected using a 1:1 stratified random sampling procedure. Patients with a history of psychiatric disorders diagnosed in 2016 were excluded. The primary end-point was the diagnosis of psychiatric disorders, evaluated from 1 January 2017 to 31 December 2021. Psychiatric disorders included schizophrenia, mood disorders, anxiety and others.

RESULTS

The analysis included 3 505 982 participants. Opioids were prescribed to 1 455 829 (41.5%) of these participants in 2016. Specifically, 1 187 453 (33.9%) individuals received opioids for 1-89 days, whereas 268 376 (7.7%) received opioids for ≥90 days. In the multivariable Cox regression model, those who received opioids had a 13% higher incidence of psychiatric disorder than those who did not (hazard ratio 1.13; 95% CI 1.13-1.14). Furthermore, both those prescribed opioids for 1-89 days and for ≥90 days had 13% (hazard ratio 1.13, 95% CI 1.12-1.14) and 17% (hazard ratio 1.17, 95% CI 1.16-1.18) higher incidences of psychiatric disorders, respectively, compared with those who did not receive opioids.

CONCLUSIONS

This study revealed that increased psychiatric disorders were associated with opioid medication use. The association was significant among both short- and long-term opioid use.

Nationwide Assessment of Chronic Pain among Hospitalized Individuals with Co-occurring Post Traumatic Stress Disorder and Substance Use Disorder in the United States

Objective: Chronic pain (CP) is independently associated with substance use disorders (SUD) and posttraumatic stress disorder (PTSD). However, little is known about factors associated with CP among patients with co-occurring PTSD and SUD. Patterns of hospital resource usage should also be explored further. Methods: Using the 2019 National Inpatient Sample (NIS), we identified 216,125 hospital discharges with co-occurring diagnoses of PTSD and SUD in 2019 and examined their association with CP. Multivariable logistic regression models were used to identify factors associated with an increased likelihood of CP in this cohort. Results: Among those with co-occurring PTSD and SUD (N = 216,125), 35,450 had associated CP, a prevalence of 164.02 cases per 1,000 discharges (95% CI [160.54, 167.52]). Individuals aged 55-64 with co-occurring PTSD and SUD were approximately 7.2 times more likely to experience CP, compared to those aged 16-24 (OR = 7.2; 95% CI [6.09, 8.60]). Being in the CP group was associated with 50% increased odds of insomnia and obesity (OR = 1.5; 95% CI [1.12, 2.03] and OR = 1.5; 95% CI [1.38, 1.55], respectively), 30% increased odds of anxiety (OR = 1.3; 95% CI [1.24, 1.38]), 20% increased odds of attention deficit disorder (ADD;OR = 1.2; 95% CI [1.12, 1.38]) and 10% increased odds of depression (OR = 1.1; 95% CI [1.01, 1.14]). Compared with females, being male was associated with slightly decreased odds of CP (OR = 0.9; 95% CI [0.84, 0.94]). Conclusions: Among hospitalized Americans with co-occurring PTSD and SUD, advanced age, being female, and the presence other mental health disorders were associated with an increased risk of CP. Providers treating co-occurring PTSD/SUD should evaluate for and consider evidence-based management of CP if present.

The effect of somatic pain and comorbid mental distress on oral health-related quality of life in orthodontic patients

OBJECTIVES

The purpose of the present study was to evaluate the prevalence of somatic pain in orthodontic patients and determine whether somatic pain contributes to worsening oral health-related quality of life (OHRQoL) through the mediating effect of psychological discomfort.

MATERIALS AND METHODS

Scale measurements and analyses were conducted on a cohort of 769 orthodontic outpatients, encompassing Patient Health Questionnaire-15-pain (PHQ-15-P), Hua-Xi Emotional-Distress Index (HEI), Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ), and Oral Health Impact Profile-14 (OHIP-14).

RESULTS

Among the respondents, 56.3% (N = 433) reported somatic pain and 20.0% (N = 154) had mental discomfort based on PHQ-15-P and HEI scores. Patients with somatic pain symptoms had significantly higher scores of HEI and OHIP-14 (P < 0.001), and higher PHQ-15-P and HEI scores emerged as statistically significant predictors of lower OHIP-14 scores (P < 0.001). HEI scores which assessed anxiety and depression partially mediated the correlation between PHQ-15-P and OHIP-14 scores, of which anxiety accounted for 52.9% of the overall mediation effect, dominating the indirect effect.

CONCLUSION

Orthodontic patients reporting somatic pains were at a significantly higher risk of worsening OHRQoL during treatment, and this adverse effect is partially mediated by anxiety and depression.

CLINICAL RELEVANCE

Our findings highlight the necessity for the assessment of general health and mental well-being during orthodontic interventions. To prevent delays in treating general disorders and the potential failure of orthodontic treatments, we encourage increased attentiveness towards patients with somatic symptoms and consideration of the adverse effects of comorbid mental distress.

Chronic pain as an emergent property of a complex system and the potential roles of psychedelic therapies

Despite research advances and urgent calls by national and global health organizations, clinical outcomes for millions of people suffering with chronic pain remain poor. We suggest bringing the lens of complexity science to this problem, conceptualizing chronic pain as an emergent property of a complex biopsychosocial system. We frame pain-related physiology, neuroscience, developmental psychology, learning, and epigenetics as components and mini-systems that interact together and with changing socioenvironmental conditions, as an overarching complex system that gives rise to the emergent phenomenon of chronic pain. We postulate that the behavior of complex systems may help to explain persistence of chronic pain despite current treatments. From this perspective, chronic pain may benefit from therapies that can be both disruptive and adaptive at higher orders within the complex system. We explore psychedelic-assisted therapies and how these may overlap with and complement mindfulness-based approaches to this end. Both mindfulness and psychedelic therapies have been shown to have transdiagnostic value, due in part to disruptive effects on rigid cognitive, emotional, and behavioral patterns as well their ability to promote neuroplasticity. Psychedelic therapies may hold unique promise for the management of chronic pain.

How Treatment Motivation Predicts Favorable Outcomes in Interdisciplinary Multimodal Pain Treatment Among Patients with Chronic Primary Pain

As motivation for psychological treatment at intake has been shown to predict favorable outcomes after an inpatient stay, this study aimed to further characterize the different components of psychological treatment motivation that predict favorable treatment outcomes. 294 inpatients with chronic primary pain participating in an interdisciplinary multimodal pain treatment in a tertiary psychosomatic university clinic completed a battery of psychological questionnaires at intake and discharge. Treatment motivation was assessed at intake using the scales of the FPTM-23 questionnaire, while pain intensity, pain interference, anxiety, and depression were assessed both at intake and discharge. After treatment, pain intensity, pain interference, anxiety, and depression were significantly reduced. While higher levels on the FPTM-23 scale of suffering predicted smaller decreases in anxiety after treatment, higher scores on the scale of hope, i.e., lower levels of hopelessness, predicted lower levels of pain interference, anxiety, and depression after treatment. None of the scales of treatment motivation predicted pain intensity levels after treatment. Above and beyond providing symptom relief, reducing hopelessness and fostering hope regarding the treatment process and outcome might help clinicians treat patients with chronic primary pain more effectively.

Enhanced anxiety-like behavior induced by chronic neuropathic pain and related parvalbumin-positive neurons in male rats

Anxiety commonly co-occurs with and exacerbates pain, but the interaction between pain progression and anxiety, and its underlying mechanisms remain unclear. Inhibitory interneurons play a crucial role in maintaining normal central nervous system function and are suggested to be involved in pain-induced anxiety. This study aimed to elucidate the time-dependent effects of neuropathic pain on the developmental anxiety-like behaviors and related inhibitory interneurons; parvalbumin (PV)- and cholecystokinin (CCK)-positive neurons in corticolimbic regions. Using an 8-week-old male Wistar rat model with partial sciatic nerve ligation (pSNL), anxiety-like behaviors were biweekly assessed post-surgery through open field (OF) and elevated plus maze (EPM) tests. From 4 weeks post-surgery, pSNL rats exhibited reduced OF center time, rearing, and initial activity, along with diminished EPM open-arm activities (time spent, head dips, movement, and rearing), which correlated with the paw withdrawal threshold. These effects were absent at 2 weeks post-surgery. At 8 weeks post-surgery, specific behaviors (decreased total rearing and increased inactive time in EPM) were observed in the pSNL group. Immunohistochemistry revealed changes in PV- and CCK-positive neurons in specific corticolimbic subregions of pSNL rats at 8 weeks post-surgery. Notably, PV-positive neuron densities in the basolateral amygdaloid complex (BLC) and hippocampal cornu ammonis areas 1 and 2 correlated with anxiety-like behavioral parameters. PV-positive neurons in the BLC of pSNL rats were predominantly changed in large-cell subtypes and were less activated. These findings indicate that anxiety-like behaviors emerge in the late phase of neuropathic pain and relate to PV-positive neurons in corticolimbic regions of pSNL rats.

A qualitative longitudinal study of traumatic orthopaedic injury survivors' experiences with pain and the long-term recovery trajectory

OBJECTIVES

To explore trauma patients' experiences of the long-term recovery pathway during 18 months following hospital discharge.

DESIGN

Longitudinal qualitative study.

SETTING AND PARTICIPANTS

Thirteen trauma patients with injuries associated with pain that had been interviewed 6 weeks after discharge from Oslo University Hospital in Norway, were followed up with an interview 18 months postdischarge.

METHOD

The illness trajectory framework informed the data collection, with semistructured, in-depth interviews that were analysed thematically.

RESULTS

Compared with the subacute phase 6 weeks postdischarge, several participants reported exacerbated mental and physical health, including increased pain during 18 months following discharge. This, andalternating periods of deteriorated health status during recovery, made the pathway unpredictable. At 18 months post-discharge, participants were coping with experiences of reduced mental and physical health and socioeconomic losses. Three main themes were identified: (1) coping with persistent pain and reduced physical function, (2) experiencing mental distress without access to mental healthcare and (3) unmet needs for follow-up care. Moreover, at 18 months postdischarge, prescribed opioids were found to be easily accessible from GPs. In addition to relieving chronic pain, motivations to use opioids were to induce sleep, reduce withdrawal symptoms and relieve mental distress.

CONCLUSIONS AND IMPLICATIONS

The patients' experiences from this study establish knowledge of several challenges in the trauma population's recovery trajectories, which may imply that subacute health status is a poor predictor of long-term outcomes. Throughout recovery, the participants struggled with physical and mental health needs without being met by the healthcare system. Therefore, it is necessary to provide long-term follow-up of trauma patients' health status in the specialist health service based on individual needs. Additionally, to prevent long-term opioid use beyond the subacute phase, there is a need to systematically follow-up and reassess motivations and indications for continued use throughout the recovery pathway.

Is psychiatric diagnostic remission associated with reduced prevalence of moderate to severe pain interference and improved functioning among adults with lifetime psychiatric disorders?

BACKGROUND

Chronic pain and non-substance use psychiatric disorders (PD) are common comorbidities, both associated with impaired functioning. However, whether and how the prevalence of pain differs in remitted PD compared to past-year PD has been little studied.

METHODS

In this observational study using data from the National Epidemiologic Survey on Alcohol and Related Conditions III, we compared the prevalence of moderate/severe pain interference (PI) in past-year Vs remitted PD among adults with any lifetime PD. We further studied the association of both PI and PD remission with mental and physical function.

RESULTS

In a sample representative of 77.9 million US adults with lifetime PDs, 31.7 % met criteria for PD remission. The prevalence and adjusted odds of PI was substantially lower among those with remitted PD compared to past-year PD (21.97 % Vs 35.02 %; p < .0001; Odds ratio 0.58, 95 % confidence interval = 0.51-0.66). While PI was independently associated with poorer mental functioning (Regression coefficient (RC) = -4.43, standard error (SE) = 0.33; p < .0001), PD remission was associated with higher mental functioning (RC = 4.79, SE = 0.24; p < .0001). Both PI and PD remission were independently associated with lower physical functioning, but the association was substantially stronger with PI (RC = -15.04, SE 0.27; p < .0001) than PD remission (RC = -0.37, SE 0.15; p = .016).

CONCLUSIONS

The negative association of PD remission with PI and their strong associations with mental functioning, albeit in opposite directions, raises the need to further examine PD as a contributing factor in chronic pain and as a target in its treatment.

Fatal drug overdoses in individuals treated pharmacologically for chronic pain: a nationwide register-based study

INTRODUCTION

Chronic pain patients may be at an increased risk for drug overdoses as a result of comorbid psychiatric disorders and treatment with risk-increasing prescription medications, such as opioids. We aimed to characterise fatal drug overdoses and investigate factors associated with the deaths among individuals who had been treated pharmacologically for chronic pain.

METHODS

We included all individuals who received analgesics reimbursed for chronic pain in Norway during 2010-9 (n=569 047). Among this population, we identified all individuals with drug overdoses as cause of death (cases). Extracting data from national registries on diagnoses, filled prescriptions, and socioeconomic variables, we used a nested case-control design to compare the cases with age- and sex-matched controls from the study population.

RESULTS

Overall, 623 (0.11%) individuals in the study population died of an overdose. Most, 66.8%, had overdosed accidentally, and 61.9% as a result of pharmaceutically available opioids. Compared with the controls (n=62 245), overdoses overall were associated strongly with substance use disorders (adjusted odds ratio 7.78 [95% confidence interval 6.20-9.77]), use of combinations of opioids, benzodiazepines and related drugs and gabapentinoids (4.60 [3.62-5.85]), previous poisoning with pharmaceuticals (2.78 [2.20-3.51]), and with living alone the last year of life (2.11 [1.75-2.54]). Intentional overdoses had a stronger association with previous poisonings with pharmaceuticals whereas accidental overdoses were strongly associated with substance use disorders.

CONCLUSIONS

This study shows the need for better identification of overdose and suicide risk in individuals treated for chronic pain. Extra caution is needed when treating complex comorbid disorders, especially with overdose risk-increasing medications.

Potentiation of the lateral habenula-ventral tegmental area pathway underlines the susceptibility to depression in mice with chronic pain

Chronic pain often develops severe mood changes such as depression. However, how chronic pain leads to depression remains elusive and the mechanisms determining individuals' responses to depression are largely unexplored. Here we found that depression-like behaviors could only be observed in 67.9% of mice with chronic neuropathic pain, leaving 32.1% of mice with depression resilience. We determined that the spike discharges of the ventral tegmental area (VTA)-projecting lateral habenula (LHb) glutamatergic (Glu) neurons were sequentially increased in sham, resilient and susceptible mice, which consequently inhibited VTA dopaminergic (DA) neurons through a LHbGlu-VTAGABA-VTADA circuit. Furthermore, the LHbGlu-VTADA excitatory inputs were dampened via GABAB receptors in a pre-synaptic manner. Regulation of LHb-VTA pathway largely affected the development of depressive symptoms caused by chronic pain. Our study thus identifies a pivotal role of the LHb-VTA pathway in coupling chronic pain with depression and highlights the activity-dependent contribution of LHbGlu-to-VTADA inhibition in depressive behavioral regulation.

CCL2 Potentiates Inflammation Pain and Related Anxiety-Like Behavior Through NMDA Signaling in Anterior Cingulate Cortex

Previous studies have shown that the C-C motif chemokine ligand 2 (CCL2) is widely expressed in the nervous system and involved in regulating the development of chronic pain and related anxiety-like behaviors, but its precise mechanism is still unclear. This paper provides an in-depth examination of the involvement of CCL2-CCR2 signaling in the anterior cingulate cortex (ACC) in intraplantar injection of complete Freund's adjuvant (CFA) leading to inflammatory pain and its concomitant anxiety-like behaviors by modulation of glutamatergic N-methyl-D-aspartate receptor (NMDAR). Our findings suggest that local bilateral injection of CCR2 antagonist in the ACC inhibits CFA-induced inflammatory pain and anxiety-like behavior. Meanwhile, the expression of CCR2 and CCL2 was significantly increased in ACC after 14 days of intraplantar injection of CFA, and CCR2 was mainly expressed in excitatory neurons. Whole-cell patch-clamp recordings showed that the CCR2 inhibitor RS504393 reduced the frequency of miniature excitatory postsynaptic currents (mEPSC) in ACC, and CCL2 was involved in the regulation of NMDAR-induced current in ACC neurons in the pathological state. In addition, local injection of the NR2B inhibitor of NMDAR subunits, Ro 25-6981, attenuated the effects of CCL2-induced hyperalgesia and anxiety-like behavior in the ACC. In summary, CCL2 acts on CCR2 in ACC excitatory neurons and participates in the regulation of CFA-induced pain and related anxiety-like behaviors through upregulation of NR2B. CCR2 in the ACC neuron may be a potential target for the treatment of chronic inflammatory pain and pain-related anxiety.

Physical activity, sitting time, and thermal quantitative sensory testing responses in African Americans

Introduction

Prior research suggests that African Americans (AAs) have more frequent, intense, and debilitating pain and functional disability compared with non-Hispanic Whites (NHWs). Potential contributing factors to this disparity are physical activity and sedentary behavior, given that AAs are less physically active, and physical activity is associated with antinociception (whereas sedentary behavior is linked to pronociception). However, impact of these factors on pain processing has largely been unexplored in AAs, especially before chronic pain onset.

Objective

This study examined relationships between physical activity, sedentary behavior (sitting time), and laboratory measures of pain and pain modulation in adult AAs. These included heat pain threshold and tolerance, temporal summation of pain (TSP, a marker of central sensitization), and conditioned pain modulation (CPM, a marker of descending pain inhibition).

Methods

Multiple regressions were conducted to examine the effects of physical activity and sitting time on heat threshold and tolerance. Multilevel models were conducted to assess the relationship between physical activity, sitting time, and temporal summation of pain. Additional multilevel models were conducted to assess the relationship between physical activity, sitting time, and conditioned pain modulation.

Results

Higher level of physical activity, but not sitting time, was associated with reduced TSP slopes. Neither physical activity nor sitting time was associated with CPM slopes. No significant relationships between physical activity or sitting time and heat pain threshold or tolerance were detected.

Conclusions

These findings suggest that physical activity is associated with reduced TSP, an effect which may be driven by reduced spinal hyperexcitability in more active individuals. Thus, structural and individual interventions designed to increase physical activity in healthy, young AAs may be able to promote antinociceptive processes (ie, reduced TSP/reduced pain facilitation) potentially protective against chronic pain.

Motive Satisfaction Among Patients with Chronic Primary Pain: A Replication

We set out to replicate findings of significant (a) reductions in pain, psychological distress, and motivational incongruence (i.e., insufficient motive satisfaction) after interdisciplinary multimodal pain treatment and (b) associations between reductions in motivational incongruence (i.e., improved motive satisfaction) and decreases in psychological distress (Vincent et al., Journal of Clinical Psychology in Medical Settings 28:331-343, 2021). 475 Patients with chronic primary pain completed standardized self-reported questionnaires assessing motivational incongruence, psychological distress, pain intensity, and pain interference at intake and discharge from a tertiary psychosomatic university clinic. We used hierarchical linear models to analyze motivational incongruence's effects on psychological distress. We partially replicated Vincent et al.'s findings. Significant reductions in pain, psychological distress, and motivational incongruence after treatment were found. Reductions in motivational incongruence were associated with reductions in psychological distress. Similarly, a better motive satisfaction mediated the relationship between pain interference and psychological distress. Our findings show that reducing motivational incongruence may be a key component of treating chronic primary pain; we recommend to assess and target motivational incongruence to improve interdisciplinary multimodal pain treatment.

Consensus on the detection and management of patients with depression and pain as an associated somatic symptom

INTRODUCTION

Globally, depression is the most common psychiatric disorder and is frequently associated with somatic symptom disorders, including pain as a physical symptom. There is a current need to improve the detection and management of the individuals in which depression and pain coexist. Hence, the aim of this document is to provide recommendations in the diagnosis and management of patients with major depressive disorder (MDD) who have pain as a physical symptom (PPS), in order to reduce the variability of clinical practice.

MATERIAL AND METHODS

The methodology used is based on the internationally recognized RAND/UCLA consensus method. The scientific committee, consisted of a group of eight multidisciplinary experts, defined 12 clinically relevant questions. After the systematic review of the literature, the scientific committee assessed the evidence and developed recommendations. The panel group with 15 participants validated these recommendations using a single Delphi round. To conclude, there was a final consensus meeting held to redefine with minor modifications the final recommendations.

RESULTS

The scientific committee developed a total of 19 recommendations on the diagnosis and detection, impact of PPS in MDD, treatment of MDD with associated PPS, use of healthcare resources, additional recommendations, and care coordination of these patients. Globally, a substantial level of agreement (≥80%) was reached on all items during the Delphi round. All the 19 achieved consensus, seven of them (37%) were agreed with unanimity during the Delphi round. The recommendations with higher consensus were in relation to diagnosis, impact of PPS in MDD, treatment and use of healthcare resources.

CONCLUSIONS

Currently, the evidence base for patients with MDD and PPS is still being developed and this consensus statement aims to bridge that gap by providing practical recommendations.

Patterns of suboptimal antipsychotic use and misuse in Australia: What can routinely collected data tell us?

AIMS

There are increasing concerns about harms related to suboptimal antipsychotic use. Here we describe recent population-based trends in antipsychotic use and harms in Australia and identify population groups exhibiting patterns of use likely to contribute to these harms.

METHODS

Using population-based data from the Australian Pharmaceutical Benefits Scheme (2015-2020), poisoning calls to the New South Wales (NSW) Poisons Information Centre (2015-2020) and poisoning deaths in all coronial records (2005-2018) in Australia, we measured trends in the prevalence of antipsychotic use and related deaths and poisonings. We applied latent class analyses to identify patterns of antipsychotic use that may contribute to harms.

RESULTS

Quetiapine and olanzapine had the highest prevalence of use between 2015 and 2020. Noteworthy trends included increases of 9.1% and 30.8% in quetiapine use and poisonings, while olanzapine use decreased by 4.5% but poisonings increased by 32.7%. Quetiapine and olanzapine poisonings and related deaths had the highest rates of co-ingestion of opioids, benzodiazepines and pregabalin compared to other antipsychotics. We identified six distinct population groups using antipsychotics: (i) ongoing high-dose use with sedatives (8%), (ii) ongoing use (42%), (iii) ongoing use with analgesics and sedatives (11%), (iv) long-term low-dose use (9%), (v) sporadic use (20%) and (vi) sporadic use with analgesics (10%).

CONCLUSION

Ongoing potentially suboptimal antipsychotic use and associated harms highlight the need to monitor such patterns of use, for example through prescription monitoring systems.

Interpretation of the Patient Health Questionnaire 9 in High-Impact Chronic Pain: Do We Measure Depressive Symptoms the Way We Think?

OBJECTIVES

Depression is prevalent among patients with chronic pain and may impact pain management. An accurate assessment is, however, complicated by overlapping symptoms. This study investigated how patients with high-impact chronic pain interpreted and responded to the Patient Health Questionnaire 9 (PHQ-9) to identify problematic items and causes hereof.

MATERIALS AND METHODS

Cognitive interviews using the Three-Step Test-Interview procedure were conducted during the completion of the PHQ-9 in 33 patients with high-impact chronic pain referred to interdisciplinary treatment. Responses were analyzed using 4 coding categories: (1) "congruent" (response consistent with intention); (2) "incongruent" (response not consistent intention); (3) "ambiguous" (response both congruent and incongruent or insufficient to evaluate congruency); and (4) "confused" (response with confused or misunderstood statements). Next, the content of responses to problematic items was analyzed to identify causes for noncongruency, and encountered response difficulties were identified across all items.

RESULTS

Three items (items 2, 6, and 9) performed as intended (>97% congruent responses), while 7 items (items 1, 3, 4, 5, 7, 8, and 10) were identified as problematic (<50% congruent responses). Problematic items had 1 or more issues: Responses were based on (1) pain-related issues or (2) other (non-pain) factors unrelated to depression, or item structure caused response difficulties due to wordings, reversion, or having 2 questions in 1.

DISCUSSION

Problematic items limit the construct validity of the PHQ-9, leaving an increased risk of inflated depression scores in high-impact chronic pain. Identified problems should guide future revisions to enhance validity and screening accuracy for the benefit of both research and clinical practice.

Evaluation of common prescription analgesics and adjuvant analgesics as markers of suicide risk: a longitudinal population-based study in England

Background

Analgesics prescriptions may provide a marker for identifying individuals at higher risk of suicide. In particular, awareness of which analgesics are implicated may help clinicians assess and modify risk.

Method

A case-control study in England using the Clinical Practice Research Datalink (for primary care records) linked with hospital and national mortality electronic registries. We included patients aged ≥15 who died by suicide between 2001 and 2019 (N = 14,515), to whom we individually matched 580,159 controls by suicide date and general practice (N = 594,674). Odds ratios (ORs) for suicide, controlled for age and sex, were assessed using conditional logistic regression.

Findings

Suicide risks were highest in those prescribed adjuvant analgesics (pregabalin, gabapentin and carbamazepine) (adjusted OR 4.07; 95% confidence intervals CI: 3.62-4.57), followed by those prescribed opioids (adjusted OR 2.01; 95% CI: 1.88-2.15) and those prescribed non-opioid analgesics (adjusted OR 1.48; 95% CI: 1.39-1.58) compared to those not prescribed these medications. By individual analgesic, the highest suicide risks were seen in patients prescribed oxycodone (adjusted OR 6.70; 95% CI: 4.49-9.37); pregabalin (adjusted OR 6.50; 95% CI: 5.41-7.81); morphine (adjusted OR 4.54; 95% CI: 3.73-5.52); and gabapentin (adjusted OR 3.12; 95% CI: 2.59-3.75). Suicide risk increased linearly with the number of analgesic prescriptions in the final year (p < 0.01 based on the likelihood ratio test), and the more different analgesics categories were prescribed in the final year (p < 0.01 based on the likelihood ratio test).

Interpretation

Analgesic prescribing was associated with higher suicide risk. This is a particular issue with regard to adjuvant non-opiate analgesics.

Funding

There was no funding for this study.

Inhibition of T-Type Calcium Channels With TTA-P2 Reduces Chronic Neuropathic Pain Following Spinal Cord Injury in Rats

Spinal cord injury (SCI)-induced neuropathic pain (SCI-NP) develops in up to 60 to 70% of people affected by traumatic SCI, leading to a major decline in quality of life and increased risk for depression, anxiety, and addiction. Gabapentin and pregabalin, together with antidepressant drugs, are commonly prescribed to treat SCI-NP, but their efficacy is unsatisfactory. The limited efficacy of current pharmacological treatments for SCI-NP likely reflects our limited knowledge of the underlying mechanism(s) responsible for driving the maintenance of SCI-NP. The leading hypothesis in the field supports a major role for spontaneously active injured nociceptors in driving the maintenance of SCI-NP. Recent data from our laboratory provided additional support for this hypothesis and identified the T-type calcium channels as key players in driving the spontaneous activity of SCI-nociceptors, thus providing a rational pharmacological target to treat SCI-NP. To test whether T-type calcium channels contribute to the maintenance of SCI-NP, male and female SCI and sham rats were treated with TTA-P2 (a blocker of T-type calcium channels) to determine its effects on mechanical hypersensitivity (as measured with the von Frey filaments) and spontaneous ongoing pain (as measured with the conditioned place preference paradigm), and compared them to the effects of gabapentin, a blocker of high voltage-activated calcium channels. We found that both TTA-P2 and gabapentin reduced mechanical hypersensitivity in male and females SCI rats, but surprisingly only TTA-P2 reduced spontaneous ongoing pain in male SCI rats. PERSPECTIVES: SCI-induced neuropathic pain, and in particular the spontaneous ongoing pain component, is notoriously very difficult to treat. Our data provide evidence that inhibition of T-type calcium channels reduces spontaneous ongoing pain in SCI rats, supporting a clinically relevant role for T-type channels in the maintenance of SCI-induced neuropathic pain.

Design and Evaluation of Deep Learning Models for Continuous Acute Pain Detection Based on Phasic Electrodermal Activity

The current method for assessing pain in clinical practice is subjective and relies on self-reported scales. An objective and accurate method of pain assessment is needed for physicians to prescribe the proper medication dosage, which could reduce addiction to opioids. Hence, many works have used electrodermal activity (EDA) as a suitable signal for detecting pain. Previous studies have used machine learning and deep learning to detect pain responses, but none have used a sequence-to-sequence deep learning approach to continuously detect acute pain from EDA signals, as well as accurate detection of pain onset. In this study, we evaluated deep learning models including 1-dimensional convolutional neural networks (1D-CNN), long short-term memory networks (LSTM), and three hybrid CNN-LSTM architectures for continuous pain detection using phasic EDA features. We used a database consisting of 36 healthy volunteers who underwent pain stimuli induced by a thermal grill. We extracted the phasic component, phasic drivers, and time-frequency spectrum of the phasic EDA (TFS-phEDA), which was found to be the most discerning physiomarker. The best model was a parallel hybrid architecture of a temporal convolutional neural network and a stacked bi-directional and uni-directional LSTM, which obtained a F1-score of 77.8% and was able to correctly detect pain in 15-second signals. The model was evaluated using 37 independent subjects from the BioVid Heat Pain Database and outperformed other approaches in recognizing higher pain levels compared to baseline with an accuracy of 91.5%. The results show the feasibility of continuous pain detection using deep learning and EDA.

Baseline Profiles of Drug Prescriptions Prior to Diagnosis of Mild Cognitive Impairment (MCI) Obtained by Latent Class Analysis (LCA), and Assessment of Their Association with Conversion to Dementia

Polypharmacy has been linked to cognitive decline. However, interventions targeting modifiable risk factors, some of which are targets of the most commonly used drugs, could reduce the prevalence of dementia. Our aim was to determine the drug prescription regimen at baseline, prior to the diagnosis of mild cognitive impairment (MCI), and its possible association with progression to dementia. Data were collected from the electronic medical records of 342 MCI outpatients diagnosed during 2006-2017 at their first neurology consultation. We followed the classical three-step method of statistical analysis, starting with a Latent Class Analysis (LCA) to discover subgroups of drug prescription probability. Half of the patients were under polypharmacy (≥5 drugs), 17.5% had no recorded medication, 33.3% progressed to dementia (94.7% in ≤5 years), and 84.1% of them to Alzheimer's disease (AD). According to the LCA and based on 20 therapeutic indicators obtained from 240 substances and regrouped according the Anatomical Therapeutic Chemical Classification, we identified a four-profile model: (1) low (35.7% of patients); (2) mixed (28.7%); (3) cardio-metabolic (19.3%); and (4) psychotropic (16.4%). The binomial regression logistic model showed that profiles 2 and 3 (and 4 for AD), with a higher drug prescription conditioned probability against classic risk factors, were protective than profile 1 (OR = 0.421, p = 0.004; OR = 0.278, p = 0.000; OR = 0.457, p = 0.040, respectively), despite polypharmacy being significant in profiles 2 and 3 (mean > 7 drugs) vs. profile 1 (1.4 ± 1.6) (p = 0.000). Patients in the latter group were not significantly older, although being aged 65-79 years old quadrupled (OR = 4.217, p = 000) and being >79 tripled (OR = 2.945, p = 0.010) the conversion risk compared to patients <65 years old. According to the proposed analytical model, profiling the heterogeneous association of risk factors, which were taken prior to diagnosis, could be explored as an indicator of prior care and a predictor of conversion to dementia.

Mental disorder prevalence in chronic pain patients using opioid versus non-opioid analgesics: A registry-linkage study

BACKGROUND

Chronic pain and mental disorders are leading causes of disability worldwide. Individuals with chronic pain are more likely to experience mental disorders compared to individuals without chronic pain, but large-scale estimates are lacking. We aimed to calculate overall prevalence of mental health diagnoses from primary and secondary care among individuals treated for chronic pain in 2019 and to compare prevalence among chronic pain patients receiving opioid versus non-opioid analgesics, according to age and gender.

METHODS

It is a population-based cohort study. Linked data from nationwide health registers on dispensed drugs and diagnoses from primary (ICPC-2) and secondary (ICD-10) health care. Chronic pain patients were identified as all patients over 18 years of age filling at least one prescription of an analgesic reimbursed for non-malignant chronic pain in both 2018 and 2019 (N = 139,434, 69.3% women).

RESULTS

Prevalence of any mental health diagnosis was 35.6% (95% confidence interval: 35.4%-35.9%) when sleep diagnoses were included and 29.0% (28.8%-29.3%) when excluded. The most prevalent diagnostic categories were sleep disorders (14% [13.8%-14.2%]), depressive and related disorders (10.1% [9.9%-10.2%]) and phobia and other anxiety disorders (5.7% [5.5%-5.8%]). Prevalence of most diagnostic categories was higher in the group using opioids compared to non-opioids. The group with the highest overall prevalence was young women (18-44 years) using opioids (50.1% [47.2%-53.0%]).

CONCLUSIONS

Mental health diagnoses are common in chronic pain patients receiving analgesics, particularly among young individuals and opioid users. The combination of opioid use and high psychiatric comorbidity suggests that prescribers should attend to mental health in addition to somatic pain.

SIGNIFICANCE

This large-scale study with nation-wide registry data supports previous findings of high psychiatric burden in chronic pain patients. Opioid users had significantly higher prevalence of mental health diagnoses, regardless of age and gender compared to users of non-opioid analgesics. Opioid users with chronic pain therefore stand out as a particularly vulnerable group and should be followed up closely by their physician to ensure they receive sufficient care for both their mental and somatic symptoms.

Enhanced AMPAR-dependent synaptic transmission by S-nitrosylation in the vmPFC contributes to chronic inflammatory pain-induced persistent anxiety in mice

Chronic pain patients often have anxiety disorders, and some of them suffer from anxiety even after analgesic administration. In this study, we investigated the role of AMPAR-mediated synaptic transmission in the ventromedial prefrontal cortex (vmPFC) in chronic pain-induced persistent anxiety in mice and explored potential drug targets. Chronic inflammatory pain was induced in mice by bilateral injection of complete Freund's adjuvant (CFA) into the planta of the hind paws; anxiety-like behaviours were assessed with behavioural tests; S-nitrosylation and AMPAR-mediated synaptic transmission were examined using biochemical assays and electrophysiological recordings, respectively. We found that CFA induced persistent upregulation of AMPAR membrane expression and function in the vmPFC of anxious mice but not in the vmPFC of non-anxious mice. The anxious mice exhibited higher S-nitrosylation of stargazin (an AMPAR-interacting protein) in the vmPFC. Inhibition of S-nitrosylation by bilaterally infusing an exogenous stargazin (C302S) mutant into the vmPFC rescued the surface expression of GluA1 and AMPAR-mediated synaptic transmission as well as the anxiety-like behaviours in CFA-injected mice, even after ibuprofen treatment. Moreover, administration of ZL006, a small molecular inhibitor disrupting the interaction of nNOS and PSD-95 (20 mg·kg-1·d-1, for 5 days, i.p.), significantly reduced nitric oxide production and S-nitrosylation of AMPAR-interacting proteins in the vmPFC, resulting in anxiolytic-like effects in anxious mice after ibuprofen treatment. We conclude that S-nitrosylation is necessary for AMPAR trafficking and function in the vmPFC under chronic inflammatory pain-induced persistent anxiety conditions, and nNOS-PSD-95 inhibitors could be potential anxiolytics specific for chronic inflammatory pain-induced persistent anxiety after analgesic treatment.

Persistent peripheral inflammation and pain induces immediate early gene activation in supraspinal nuclei in rats

Pain is a public health concern worldwide and can present simultaneously with anxiety and depression. c-Fos is a marker used to identify activated cells in response to various stimuli. Specifically, it can be used as a brain marker of pain. We examined whether peripheral inflammation produces mechanical allodynia, anxiety- and depression-related behaviors in male rats (Rattus norvegicus, Wistar strain) and if these behaviors can have an impact on c-Fos expression in the supraspinal nuclei involved in pain control. We assessed mechanical thresholds by von Frey monofilaments, depression-like behaviors in the forced swimming test (FST) and anxiety-related behaviors in the open field test (OFT) after the administration of the inflamogen Complete Freund´s Adjuvant (CFA) in rats. We found that CFA increased paw diameter is all rats, however, CFA treatment resulted in a subgroup of rats developing allodynia [CFA- mechanical allodynia (CFA-MA)] and a subgroup of rats not developing allodynia [CFA-no mechanical allodynia (CFA-NMA)]. At the peak of tactile allodynia and inflammation, results were coupled with an increase in c-Fos expression in several supraspinal brain nuclei, i.e. basolateral amygdala, periaqueductal gray matter and rostroventromedial medulla in CFA-MA rats. Moreover, we found a correlation between c-Fos levels and mechanical thresholds. No modification in c-Fos expression was observed in CFA-NMA rats. CFA did not modulate behaviors in the OFT or FST. In summary, we show that mechanical allodynia but not peripheral inflammation activates c-Fos in several supraspinal nuclei, which sheds new light on brain regions involved in the control of pain following peripheral injury and decouples this effect from mere peripheral inflammation. This model may be used to study resistance to pain development in future studies.

Improvements in pain coping predict treatment success among patients with chronic primary pain

OBJECTIVE

Given the increasing incidence and prevalence of chronic pain, effective treatments for chronic pain are needed. This study aimed to investigate the role of cognitive and behavioral pain coping regarding the prediction of treatment outcomes among inpatients with chronic primary pain participating in an interdisciplinary multimodal treatment program.

METHODS

At intake and discharge, 500 patients with chronic primary pain completed questionnaires on pain intensity, pain interference, psychological distress, and pain processing.

RESULTS

Patients' symptoms, cognitive and behavioral pain coping improved significantly after treatment. Similarly, separate cognitive and behaviroal coping skills improved significantly after treatment. Hierarchical linear models revealed no significant associations of pain coping with reductions in pain intensity. Whereas the overall level and improvements in cognitive pain coping predicted reductions in pain interference and psychological distress, the overall level and improvements in behavioral pain coping were associated with reductions in pain interference alone.

DISCUSSION

Since pain coping seems to influence both pain interference and psychological distress, improving cognitive and behavioral pain coping during an interdisciplinary multimodal pain treatment seems to be a key component in the successful treatment of inpatients with chronic primary pain, enabling them to function better physically and mentally despite their chronic pain. Clinically, it might be worth fostering and exercising cognitive restructuring as well as action planning in treatment to reduce both pain interference and psychological distress levels post-treatment. In addition, practicing relaxation techniques might help reduce pain interference post-treatment, whereas making experiences of personal competence might help reduce psychological distress post-treatment.

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.

Trifluoro-icaritin ameliorates spared nerve injury-induced neuropathic pain by inhibiting microglial activation through α7nAChR-mediated blockade of BDNF/TrkB/KCC2 signaling in the spinal cord of rats

Neuropathic pain is still a serious and unsolved health problem. Activation of α7 nicotinic acetylcholine receptor (α7nAChR) is known to modulate neuropathic pain by inhibiting microglial activation and BDNF/TrkB/KCC2 signaling. We previously identified that trifluoro-icaritin (ICTF) has an attenuated effect on spared nerve injury (SNI)-induced neuropathic pain, but its potential mechanisms remain unknown. Here, the pain-related behaviors were determined by paw withdrawal threshold (PWT), CatWalk gait analysis, rotarod test, open field test and elevated plus maze test. The expression of pain-related signal molecules was evaluated by Western blot and immunofluorescence staining. The results showed that ICTF (5.0 mg/kg, i.p.) successfully relieved SNI-induced mechanical allodynia and anxiety-like behavior, we subsequently found there existed either positive or negative correlation between mechanical allodynia and gait parameters or rotating speed following ICTF treatment. Moreover, ICTF not only enhanced the expression of spinal α7nAChR, KCC2, CD206 and IL-10, but also decreased the levels of spinal BDNF, TrkB, CD11b, Iba-1, CD40 and IL-1β in SNI rats. Conversely, α7nAChR antagonist α-Bgtx (I.T.) effectively reversed the inhibitory effects of ICTF on SNI rats, resulting in a remarkable improvement of mechanical allodynia, activation of microglia. and suppression of α7nAChR-mediated BDNF/TrkB/KCC2 signaling. Additionally, exogenous BDNF (I.T.) dramatically abrogated both blockade of BDNF/TrkB/KCC2 cascade and alleviation of mechanical allodynia by ICTF treatment. Altogether, the study highlighted that ICTF could relieve SNI-induced neuropathic pain by suppressing microglial activation via α7nAChR-mediated inhibition of BDNF/TrkB/KCC2 signaling in the spinal cord, suggesting that ICTF may be served as a possible painkiller against neuropathic pain.

Pain Intensity Moderates the Association between Obsessive-Compulsive Symptoms and Problematic Alcohol Use among Emerging Adults

Objective: Emerging adulthood is a vulnerable period for problematic alcohol use, defined by a pattern of use associated with physical and functional impairment. Obsessive-compulsive psychopathology, which demonstrates high rates of onset in emerging adults, seems to be related to problematic alcohol use in this age group, consistent with research among the general population suggesting an association between emotional disorders and alcohol use in the context of coping drinking motives. Pain intensity, another risk factor of problematic alcohol use, may link obsessive-compulsive symptoms to problematic alcohol use among emerging adults. Therefore, the current study examined the moderating role of pain intensity on the association between obsessive-compulsive symptoms and problematic alcohol use among emerging adults. Methods: Participants were 198 college students (81.30% female, M_age = 22.33, SD = 4.38) who reported problematic alcohol use. Results: Results from the current study supported a significant moderation role of pain intensity for the association between obsessive-compulsive symptoms and problematic alcohol use, whereby the association between obsessive-compulsive symptoms and problematic alcohol use was stronger for emerging adults with high compared to low pain intensity. Conclusions: These results highlighted a clinically-relevant interaction between obsessive-compulsive symptoms and pain intensity concerning the risk of problematic alcohol use among emerging adults as a vulnerable population.

Artificial Neural Networks Coupled with MALDI-TOF MS Serum Fingerprinting To Classify and Diagnose Pathological Pain Subtypes in Preclinical Models

Pathological pain subtypes can be classified as either neuropathic pain, caused by a somatosensory nervous system lesion or disease, or nociplastic pain, which develops without evidence of somatosensory system damage. Since there is no gold standard for the diagnosis of pathological pain subtypes, the proper classification of individual patients is currently an unmet challenge for clinicians. While the determination of specific biomarkers for each condition by current biochemical techniques is a complex task, the use of multimolecular techniques, such as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), combined with artificial intelligence allows specific fingerprints for pathological pain-subtypes to be obtained, which may be useful for diagnosis. We analyzed whether the information provided by the mass spectra of serum samples of four experimental models of neuropathic and nociplastic pain combined with their functional pain outcomes could enable pathological pain subtype classification by artificial neural networks. As a result, a simple and innovative clinical decision support method has been developed that combines MALDI-TOF MS serum spectra and pain evaluation with its subsequent data analysis by artificial neural networks and allows the identification and classification of pathological pain subtypes in experimental models with a high level of specificity.

Effects of pain and depression on the relationship between household solid fuel use and disability among middle-aged and older adults

Household air pollution (HAP) is suggested to increases people's risk of disability, but mediating mechanisms between HAP and disability remains under-investigated. The aim of this study was to investigate the underlying mechanisms between household air pollution and disability in middle-aged and older adults (i.e., older than 45 years) using a nationally representative prospective cohort. In total, 3754 middle-aged and older adults were selected from the China Health and Retirement Longitudinal Study. Correlation analysis and logistic regression analysis were employed to estimate the association between HAP, pain, depression and disability. Finally, three significant mediation pathways through which HAP directly impacts disability were found: (1) pain (B = 0.09, 95% CI 0.01, 0.02), accounting for 15.25% of the total effect; (2) depression (B = 0.07, 95% CI 0.004, 0.02), accounting for 11.86% of the total effect; (3) pain and depression (B = 0.04, 95% CI 0.003, 0.01), accounting for 6.78% of the total effect. The total mediating effect was 33.89%. This study clarified that HAP can indirectly affect disability through the respective and serial mediating roles of pain and depression. These findings potentially have important implications for national strategies concerning the widespread use of clean fuels by citizens.

The anterior cingulate cortex contributes to the analgesic rather than the anxiolytic effects of duloxetine in chronic pain-induced anxiety

Mood disorders, such as anxiety and depression, are commonly found in people suffering from chronic pain. Serotonin-norepinephrine reuptake inhibitors (SNRIs) are potential in alleviating chronic pain and are the first-line option for anxiety disorder. The anterior cingulate cortex (ACC) plays a vital role in chronic pain-induced anxiety, but its role in the therapeutic effects of SNRIs remains largely unclear. We used complete Freund's adjuvant (CFA) in this current study to induce chronic inflammatory pain. Von Frey test was used to measure the mechanical withdrawal threshold. The elevated plus maze test (EPM) and the novelty-suppressed feeding test (NSF) were used to measure anxiety-like behaviors. Twenty-one days after the modeling, anxiety-like behaviors were successfully induced in CFA mice, and a 3-day intraperitoneal injection of duloxetine attenuated such behaviors. While, mechanical hyperalgesia was also improved. Then, we locally infused duloxetine in ACC for 3 days only to find out its analgesic effect in CFA mice. Furthermore, we used fiber photometry to discover decreased glutamatergic excitability and enhanced serotonin concentration in ACC after intraperitoneal injection of duloxetine. Overall, this study proposed a potential mechanism for the analgesic effect of duloxetine and shed light on further studies on the mechanism of its anxiolytic effect in chronic pain-induced anxiety.

Cellular mechanisms underlying central sensitization in a mouse model of chronic muscle pain

Chronic pain disorders are often associated with negative emotions, including anxiety and depression. The central nucleus of the amygdala (CeA) has emerged as an integrative hub for nociceptive and affective components during central pain development. Prior adverse injuries are precipitating factors thought to transform nociceptors into a primed state for chronic pain. However, the cellular basis underlying the primed state and the subsequent development of chronic pain remains unknown. Here, we investigated the cellular and synaptic alterations of the CeA in a mouse model of chronic muscle pain. In these mice, local infusion of pregabalin, a clinically approved drug for fibromyalgia and other chronic pain disorders, into the CeA or chemogenetic inactivation of the somatostatin-expressing CeA (CeA-SST) neurons during the priming phase prevented the chronification of pain. Further, electrophysiological recording revealed that the CeA-SST neurons had increased excitatory synaptic drive and enhanced neuronal excitability in the chronic pain states. Finally, either chemogenetic inactivation of the CeA-SST neurons or pharmacological suppression of the nociceptive afferents from the brainstem to the CeA-SST neurons alleviated chronic pain and anxio-depressive symptoms. These data raise the possibility of targeting treatments to CeA-SST neurons to prevent central pain sensitization.

Effectiveness, cost-utility and physiological underpinnings of the FIBROWALK multicomponent therapy in online and outdoor format in individuals with fibromyalgia: Study protocol of a randomized, controlled trial (On&Out study)

Introduction: The On&amp;Out study is aimed at assessing the effectiveness, cost-utility and physiological underpinnings of the FIBROWALK multicomponent intervention conducted in two different settings: online (FIBRO-On) or outdoors (FIBRO-Out). Both interventions have proved to be efficacious in the short-term but there is no study assessing their comparative effectiveness nor their long-term effects. For the first time, this study will also evaluate the cost-utility (6-month time-horizon) and the effects on immune-inflammatory biomarkers and Brain-Derived Neurotrophic Factor (BDNF) levels of both interventions. The objectives of this 6-month, randomized, controlled trial (RCT) are 1) to examine the effectiveness and cost-utility of adding FIBRO-On or FIBRO-Out to Treatment-As-Usual (TAU) for individuals with fibromyalgia (FM); 2) to identify pre–post differences in blood biomarker levels in the three study arms and 3) to analyze the role of process variables as mediators of 6-month follow-up clinical outcomes.

Methods and analysis: Participants will be 225 individuals with FM recruited at Vall d’Hebron University Hospital (Barcelona, Spain), randomly allocated to one of the three study arms: TAU vs. TAU + FIBRO-On vs. TAU + FIBRO-Out. A comprehensive assessment to collect functional impairment, pain, fatigue, depressive and anxiety symptoms, perceived stress, central sensitization, physical function, sleep quality, perceived cognitive dysfunction, kinesiophobia, pain catastrophizing, psychological inflexibility in pain and pain knowledge will be conducted pre-intervention, at 6 weeks, post-intervention (12 weeks), and at 6-month follow-up. Changes in immune-inflammatory biomarkers [i.e., IL-6, CXCL8, IL-17A, IL-4, IL-10, and high-sensitivity C-reactive protein (hs-CRP)] and Brain-Derived Neurotrophic Factor will be evaluated in 40 participants in each treatment arm (total n = 120) at pre- and post-treatment. Quality of life and direct and indirect costs will be evaluated at baseline and at 6-month follow-up. Linear mixed-effects regression models using restricted maximum likelihood, mediational models and a full economic evaluation applying bootstrapping techniques, acceptability curves and sensitivity analyses will be computed.

Ethics and dissemination: This study has been approved by the Ethics Committee of the Vall d’Hebron Institute of Research. The results will be actively disseminated through peer-reviewed journals, conference presentations, social media and various community engagement activities. Trial registration number NCT05377567 (clinicaltrials.gov).

The Role of Mental Health and Behavioral Disorders in the Development of Temporomandibular Disorder: A SWEREG-TMD Nationwide Case-Control Study

Purpose

There is a well-known association between mental and behavioral disorders (MBD) and temporomandibular disorder (TMD), although the association has not been established in population-based samples. This study aimed to investigate this relationship using national population-based registry data.

Patients and Methods

This case-control study used prospectively collected data from Swedish national registries to investigate exposure to MBD and the probability of developing TMD in all Swedish citizens with hospital-diagnosed or surgically treated TMD between 1998 and 2016. Odds ratios were calculated using conditional logistic regression adjusted for educational level, living area, country of birth, musculoskeletal comorbidity, and history of orofacial/neck trauma.

Results

A statistically significant association between MBD and TMD was found for mood affective disorders (OR 1.4), neurotic, stress-related and somatoform disorders (OR 1.7), behavioral syndromes associated with psychological disturbances and physical factors (OR 1.4), disorders of adult personality and behavior (OR 1.4), disorders of psychological development (OR 1.3), behavioral and emotional disorders with onset usually occurring in childhood and adolescence (OR 1.4), and unspecified mental disorder (OR 1.3). The association was stronger for TMD requiring surgery, with the strongest association in patients with disorders of psychological development (OR 2.9). No significant association was found with schizophrenia, schizotypal and delusional disorders, or mental retardation.

Conclusion

The findings indicate an increased probability of TMD among patients with a history of certain MBD diagnoses, and a stronger association with TMD requiring surgery, specifically repeated surgery. This highlights the need for improved preoperative understanding of the impact of MBD on TMD, as TMD and chronic pain itself may have a negative impact on mental health.

A prospective study revealing a compounded burden of COVID-19, sex, and clinical diagnosis of alcohol use disorder and HIV infection on quality of life, anxiety, and alcohol use

The COVID-19 pandemic led to unprecedented restrictions to mitigate disease spread, leading to consequences affecting mental health. Many studies examining COVID-19 pandemic effects on well-being and mental health initiated inquiry after the pandemic onset, whereas we used self-report questionnaires obtained before the pandemic to re-assess the same functions during the pandemic. Participants were drawn from our ongoing longitudinal studies of people with HIV infection, alcohol use disorder (AUD), HIV + AUD comorbidity, and controls. We used phone or mail contact to invite all to participate in our COVID phone survey, which included three self-report questionnaires: Health-related Quality of Life (QoL), State-Trait Anxiety Inventory (STAI), and Alcohol Use Disorder Identification Test (AUDIT). Of 218 eligible participants, 86 responded (July 2020-March 2021): clinical (29 men, 23 women; 17 AUD, 21 HIV, 14 HIV + AUD); control (17 men, 17 women). QoL scores declined, and anxiety symptoms increased from pre-COVID surveys in all groups; clinical women reported greater negative changes than the other groups. QoL subscales revealed COVID-related declines in emotional well-being in all groups, with clinical women reporting additional declines in energy, physical and social functioning, health, and pain increase. Clinical men also reported health declines. Although AUDIT scores were stable in all groups between assessments, changes in AUDIT scores were inversely correlated with QoL scores in clinical women; in clinical men, changes in STAI scores were inversely correlated with QoL scores. Although all groups were adversely affected by the pandemic, the negative effects were greater in the clinical group regardless of diagnosis and greatest in clinical women.

Comorbid depressive symptoms can aggravate the functional changes of the pain matrix in patients with chronic back pain: A resting-state fMRI study

Objective

The purposes of this study are to explore (1) whether comorbid depressive symptoms in patients with chronic back pain (CBP) affect the pain matrix. And (2) whether the interaction of depression and CBP exacerbates impaired brain function.

Methods

Thirty-two patients with CBP without comorbid depressive symptoms and thirty patients with CBP with comorbid depressive symptoms were recruited. All subjects underwent functional magnetic resonance imaging (fMRI) scans. The graph theory analysis, mediation analysis, and functional connectivity (FC) analysis were included in this study. All subjects received the detection of clinical depressive symptoms and pain-related manifestations.

Result

Compared with the CBP group, subjects in the CBP with comorbid depressive symptoms (CBP-D) group had significantly increased FC in the left medial prefrontal cortex and several parietal cortical regions. The results of the graph theory analyses showed that the area under the curve of small-world property (t = −2.175, p = 0.034), gamma (t = −2.332, p = 0.023), and local efficiency (t = −2.461, p = 0.017) in the CBP-D group were significantly lower. The nodal efficiency in the ventral posterior insula (VPI) (t = −3.581, p = 0.0007), and the network efficiency values (t = −2.758, p = 0.008) in the pain matrix were significantly lower in the CBP-D group. Both the topological properties and the FC values of these brain regions were significantly correlated with self-rating depression scale (SDS) scores (all FDR corrected) but not with pain intensity. Further mediation analyses demonstrated that pain intensity had a mediating effect on the relationship between SDS scores and Pain Disability Index scores. Likewise, the SDS scores mediated the relationship between pain intensity and PDI scores.

Conclusion

Our study found that comorbid depressive symptoms can aggravate the impairment of pain matrix function of CBP, but this impairment cannot directly lead to the increase of pain intensity, which may be because some brain regions of the pain matrix are the common neural basis of depression and CBP.

Psychopathological and Personality Pro file in Chronic Nononcologic Nociceptive and Neuropathic pain: Cross-sectional Comparative Study

Introduction

Adaptation to chronic non-oncologic pain is associated with the development of psychopathology and personality disorders, creating severity, chronicity, poorer treatment response, and exacerbations in patients with neuropathy.

Objective

To identify the psychopathological and personality profiles of patients with chronic nociceptive and neuropathic pain and their association with pain progression and intensity.

Method

A cross-sectional, descriptive and comparative study was conducted in the Pain Treatment Unit of Hospital Universitari Sagrat Cor, with systematic randomized recruitment for 25 months; 115 patients were evaluated using the Hamilton Depression and Anxiety Rating Scale (HAM-D, HAM-A) and the Millon Clinical MultiaxialInventory-III (MCMI-III).

Results

The neuropathic group achieved significantly higher scores for pain intensity and depressive and anxiety symptoms. With greater magnitude and frequency, the neuropathic group related pain intensity and progression with depressive/anxiety symptoms, clinical syndromes, and personality patterns. Both groups revealed tendencies towards a compulsive personality pattern, followed by narcissistic, histrionic, and schizoid patterns.

Conclusions

When treating chronic pain, the presence of various psychopathological indicators requires an individualized strategy.

Frequency and characteristics of patient exclusion criteria in Canadian multidisciplinary pain treatment facilities: a cross-sectional study

PURPOSE

A multidisciplinary approach is recommended for patients with complex chronic pain (CP). Many multidisciplinary pain treatment facilities (MTPFs) use patient exclusion criteria but little is known about their characteristics. The objective of this study was to describe the frequency and characteristics of exclusion criteria in public Canadian MTPFs.

METHODS

We conducted a cross-sectional study in which we defined an MPTF as a clinic staffed with professionals from three disciplines or more (including at least one medical specialty) and whose services were integrated within the facility. We disseminated a web-based questionnaire in 2017-2018 to the administrative leads of MPTFs across the country. They were invited to complete the questionnaire about the characteristics of their facilities. Data were analyzed using descriptive statistics and correlation measures.

RESULTS

A total of 87 MTPFs were included in the analyses. Half of them (52%) reported using three exclusion criteria or more. There was no significant association between the number of exclusion criteria and wait time for a first appointment or number of new consultations in the past year. Fibromyalgia and migraine were the most frequently excluded pain syndromes (10% and 7% of MPTFs, respectively). More than one MPTF out of four excluded patients with mental health disorders (30%) and/or substance use disorders (29%), including MPTFs with specialists in their staff.

CONCLUSIONS

Multidisciplinary pain treatment facility exclusion criteria are most likely to affect CP patients living with complex pain issues and psychosocial vulnerabilities. Policy efforts are needed to support Canadian MPTFs in contributing to equitable access to pain management.

Electroacupuncture Alleviates Anxiety-Like Behaviors Induced by Chronic Neuropathic Pain via Regulating Different Dopamine Receptors of the Basolateral Amygdala

Chronic pain, such as neuropathic pain, causes anxiety and other negative emotions, which aggravates the pain sensation and increases the risk of chronic pain over time. Dopamine receptor D1 (DRD1) and dopamine receptor D2 (DRD2) in the basolateral amygdala (BLA) have been implicated in mediating anxiety-related behaviors, but their potential roles in the BLA in neuropathic pain-induced anxiety have not been examined. Electroacupuncture (EA) is commonly used to treat chronic pain and emotional disorders, but it is still unclear whether EA plays a role in analgesia and anxiety relief through DRD1 and DRD2 in the BLA. Here, we used western blotting to examine the expression of DRD1 and DRD2 and pharmacological regulation combined with behavioral testing to detect anxiety-like behaviors. We observed that injection of the DRD1 antagonist SCH23390 or the DRD2 agonist quinpirole into the BLA contributed to anxiety-like behaviors in naive mice. EA also activated DRD1 or inhibited DRD2 in the BLA to alleviate anxiety-like behaviors. To further demonstrate the role of DRD1 and DRD2 in the BLA in spared nerve injury (SNI) model-induced anxiety-like behaviors, we injected the DRD1 agonist SKF38393 or the DRD2 antagonist sulpiride into the BLA. We found that both activation of DRD1 and inhibition of DRD2 could alleviate SNI-induced anxiety-like behaviors, and EA had a similar effect of alleviating anxiety. Additionally, neither DRD1 nor DRD2 in the BLA affected SNI-induced mechanical allodynia, but EA did. Overall, our work provides new insights into the mechanisms of neuropathic pain-induced anxiety and a possible explanation for the effect of EA treatment on anxiety caused by chronic pain.

Tailored internet-based cognitive behavioral therapy for individuals with chronic pain and comorbid psychological distress: a randomized controlled trial

Comorbid psychological problems are commonly related to chronic pain but addressing heterogeneous comorbidities in traditional settings is often difficult. Delivering individually tailored treatment using the internet could be a viable alternative. The present study investigates whether a guided, individually tailored and internet-delivered cognitive behavioral therapy (ICBT) could improve mood and reduce disability in individuals suffering from chronic pain and comorbid psychological distress.Participants were recruited from a pain clinic and randomized to either ICBT or waiting list. The participants (n = 187) individually tailored treatments included 6-13 modules targeting different types of psychological distress. Modules were designed to be completed weekly, and feedback was provided by clinicians. Participants completed an average of 5.1 (49.7%) modules, with 22.9% completing all assigned modules. Intention-to-treat analyses showed significantly larger improvements in depression, disability, pain acceptance, catastrophizing, and quality of life in the ICBT-group compared to the control group. Between-group effect sizes were very small or small at post for the primary outcomes depression (d = 0.18) and pain interference (d = 0.22). Other effect sizes ranged from very small to small, with the largest effect being improvements in pain acceptance (d = 0.3). All significant changes were stable at 12-month follow up.

Synergistic effect of chronic pain and nonsuicidal self-harm on pain sensitivity

Abnormalities in pain processing have been observed in patients with chronic pain conditions and in individuals who engage in self-harm, specifically nonsuicidal self-injurious behaviors (NSSI). Both increased and decreased pain sensitivity have been described in chronic pain patients, while decreased pain sensitivity is consistently observed in individuals with NSSI. The objective of the study was to identify the differential effects of chronic pain and NSSI on experimental pain sensitivity, specifically pressure pain threshold, in depressed patients. Moreover, the role that hopelessness may play between depression severity and pain sensitivity was also examined. Depressed patients with and without chronic pain, and with and without lifetime self-harm behaviors were analyzed into four groups. Group 1 (N = 42) included depressed patients with both Chronic pain ( +) and Self-harm ( +), Group 2 (N = 53) included depressed patients with Chronic pain ( +) but no Self-harm (-), Group 3 (N = 64) included depressed patients without Chronic pain (-), but Self-harm ( +), and Group 4 (N = 81) included depressed patients with neither Chronic pain (-) nor Self-harm (-). Healthy controls (N = 45) were also recruited from the community. Depressed patients with both Chronic pain ( +) and Self-harm ( +) reported higher pressure pain threshold measures when compared with the other groups. Mediation analysis indicated that hopelessness mediates the relationship between depression severity and pressure pain threshold. Our findings suggest that a multiprong approach including adequate mental health services and pain control for depressed patients with comorbid chronic pain and nonsuicidal self-harm is needed to yield effective outcomes.

The Experiences of Persistent Pain Among Women With a History of Intimate Partner Violence: A Systematic Review

Women experience persistent pain at higher rates than men; however, women are less likely to be provided with adequate or appropriate care and more likely to have their pain experiences dismissed. The purpose of this review is to consider the complex interaction of the biopsychosocial factors in the experience of persistent pain in order to inform improved models of care. Given persistent pain is among the most frequently reported health consequences of intimate partner violence (IPV), this review focused on studies exploring the association between persistent pain and IPV. Three reviewers independently and systematically searched seven databases. Qualitative and quantitative studies describing the association between IPV and persistent pain published between January 2000 and June 2018 were included. Twelve studies met the inclusion criteria. The included studies demonstrated that a history of IPV places an additional burden on women who experience persistent pain that cannot be explained by an underlying psychological condition. Health care practitioners should be aware of this phenomena to ensure diagnosis, assessment, and treatment plans are targeted accordingly. Future policy directives and research should account for and seek to elucidate this additional burden.

Network Analysis of Depression, Anxiety, Posttraumatic Stress Symptoms, Insomnia, Pain, and Fatigue in Clinically Stable Older Patients With Psychiatric Disorders During the COVID-19 Outbreak

OBJECTIVES

The Coronavirus Disease 2019 (COVID-19) pandemic has profound negative effects on the mental health of clinically stable older patients with psychiatric disorders. This study examined the influential nodes of psychiatric problems and their associations in this population using network analysis.

METHODS

Clinically stable older patients with psychiatric disorders were consecutively recruited from four major psychiatric hospitals in China from May 22 to July 15, 2020. Depressive and anxiety syndromes (depression and anxiety hereafter), insomnia, posttraumatic stress symptoms (PTSS), pain, and fatigue were measured using the Patient Health Questionnaire, General Anxiety Disorder, Insomnia Severity Index, Posttraumatic Stress Disorder Checklist - Civilian Version, and Numeric Rating Scales for pain and fatigue, respectively.

RESULTS

A total of 1063 participants were included. The network analysis revealed that depression was the most influential node followed by anxiety as indicated by the centrality index of strength. In contrast, the edge connecting depression and anxiety was the strongest edge, followed by the edge connecting depression and insomnia, and the edge connecting depression and fatigue as indicated by edge-weights. The network structure was invariant by gender based on the network structure invariance test (M = .14, P = .20) and global strength invariance tests (S = .08, P = .30).

CONCLUSIONS

Attention should be paid to depression and its associations with anxiety, insomnia, and fatigue in the screening and treatment of mental health problems in clinically stable older psychiatric patients affected by the COVID-19 pandemic.

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

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

Introduction:

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

Objective:

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

Methods:

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

Results:

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

Conclusions:

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

Development and Validation of a Scale for Assessing the Interference of Chronic Primary Pain Conditions in Sexual Functioning: The Sex-Pain Questionnaire

Chronic pain represents one of the main health public problems worldwide and significantly affects the sexual life of patients. However, no specific instruments of evaluation have been found that address this population. This study presents the SEX-PAIN Questionnaire, developed for identifying chronic pain's interference with sexual functioning among people with chronic pain. Methods. The validation has been carried out with a sample of 303 Spanish non-hospitalized patients with chronic pain diagnosis aged between 20 and 71 years old (Mage = 49.49; SD = 10.7). Exploratory Factor Analysis (EFA) yielded 2-factor structure: Sexual and Relationship Dissatisfaction, and Chronic Pain Impact on Sexual Life. This structure was later verified through Confirmatory Factor Analysis (CFA). Internal consistency (Omega) of each factor was .72 and .96, respectively. This study presents the psychometric properties of a new measure addressed to patients with chronic pain. This 17-items self-administered instrument can be a useful measure of the chronic pain's interference with sexual functioning among chronic pain patients. It represents the first original questionnaire known in Spanish language to date. This measure could potentially help researchers and clinicians to obtain key information to design appropriate healthcare interventions.Supplemental data for this article is available online at https://doi.org/10.1080/0092623X.2022.2039336 .

Psychological Traits of Patients With Depression Comorbid With Chronic Pain: Are Complaint and Competitive Tendency Related to Pain?

BACKGROUND

Modern-Type Depression (MTD) is a category of depression that has been studied mainly in Japan; however, no study has attempted to determine its relation to chronic pain.

AIM

To determine possible associations between psychological traits related to MTD and the chronic pain of patients at psychiatric clinics.

METHOD

Two hundred and twenty-one first time patients who visited the psychiatric clinic at a Japanese university medical center or an associated clinic were enrolled. The Hamilton Depression Rating Scale was used to measure depressive symptoms. The 22-item Tarumi's Modern-Type Depression Trait Scale (TACS-22), Achievement Motive, and 20-item Toronto Alexithymia Scale were used to assess psychological traits related to depression and chronic pain. The clinical diagnosis of each patient was confirmed by use of the Structured Clinical Interview for DSM-IV Axis I Disorders, administered by experienced specialists. The medians of the psychological traits identified were compared between patients with or without chronic pain. Analysis was also done of patients with Major Depressive Disorder (MDD).

RESULT

Of the 221 patients, 139 had chronic pain. Patients with chronic pain had more severe depressive symptoms, Alexithymia, and high scores for the complaint trait of MTD. Seventy-three of the 221 patients met the criteria for MDD (53 had chronic pain). Patients with MDD comorbid with chronic pain had a higher competitive achievement score, severe depression, and difficulty identifying feelings.

CONCLUSION

Complaint and competitive traits were shown to be related to chronic pain in psychiatric settings. Further study will allow us to design multidimensional approach for patients suffering from depression.

Does Gender Moderate the Relationship Between Chronic Pain and Substance Use Disorder? Insights From a National Canadian Population Survey

BACKGROUND

Though it has been shown that men have a higher lifetime prevalence of substance use disorder and a lower prevalence of chronic pain than women, there is little research to date focusing on gender differences in the relationship between chronic pain and substance use disorder. This study examined whether gender moderates the relationship of chronic pain and substance use disorder. We also sought to examine the gender differences in the associations between specific pain types-arthritis, migraine, and back pain, and substance use disorder.

METHODS

The data were drawn from the 2012 Canadian Community Health Survey-Mental Health (CCHS-MH 2012) with individuals aged 20 years and older living in the 10 Canadian provinces (N = 23,089). A two-level logistic mixed effects model was used to account for provincial differences.

RESULTS

Our findings indicated gender moderated the association between arthritis as well as migraine, and substance use disorder. However, no moderation effect of gender on the relationship between back pain and substance use disorder was found. Specifically, the strength of the association between arthritis and substance use disorder was stronger among men (OR_interaction = 0.62, 95% CI: 0.53 to 0.73), whereas the strength of the association between migraine and substance use disorder was stronger among women (OR_interaction = 1.45, 95% CI: 1.18 to 1.79). In addition, geographical location was found to explain a small proportion (2.3%-2.4%) of the overall variance in SUD.

CONCLUSIONS

The results suggest that gender moderated the relations between arthritis as well as migraine, and substance use disorder, respectively. Treatment programs for pain and substance misuse might benefit from an approach tailored to gender differences.