Pain and use of alcohol to manage pain: prevalence and 3-year outcomes among older problem and non-problem drinkers

Impacts of alcohol consumption on farmers' mental health: Insights from rural China

The global mental health crisis presents a significant challenge to sustainable development, and this crisis is more pronounced in China's rural areas versus urban areas. Alcohol consumption has increased in rural areas with China's economic growth, but the number of studies on the relationship between farmers' alcohol consumption and their mental health is limited. Based on data from the China Labor Force Dynamics Survey (CLDS), this study uses the endogenous switching regression model (ESR) to analyze the influence of alcohol consumption on farmers' mental health. On this basis, the study further conducts a counterfactual analysis to estimate the average treatment effect of alcohol consumption on farmers' mental health. The results show that: (1) There is a significant positive relationship between alcohol consumption and farmers' mental health. Specifically, the mental health index of drinking farmers increases by 19.7 % compared to non-drinking farmers. (2) Heterogeneity analysis shows that alcohol consumption is more beneficial for improving the mental health of male farmers, elderly farmers, and employed farmers. Furthermore, drinking alcohol almost every day, consuming Baijiu, and each drinking consumption ranging from 0 to 100 mL per occasion are more conducive to improving farmers' mental health. These findings have implications for relieving depressive symptomology and improving farmers' mental health in developing countries. The results of this study also provide guidance for addressing the global mental health crisis.

Identification of ethanol analgesia quantitative trait loci and candidate genes in BXD recombinant inbred mouse lines

Alcohol consumption produces acute analgesic effects, and people experiencing pain conditions may drink alcohol to alleviate discomfort. However, tolerance to the analgesic properties of alcohol could prompt escalating consumption and dependence. Both nociception and alcohol-induced analgesia are under significant genetic control. Understanding the genetic architecture of these processes could inform better treatment options for people with pain conditions. This study aims to identify quantitative trait loci (QTL) driving variation in ethanol-induced analgesia across BXD recombinant inbred mouse lines. Male and female mice from 62 BXD strains received ethanol or saline oral gavage for five days and were tested for hot plate (HP) latency at baseline, Day 1, and Day 5. QTL mapping of HP phenotypes identified a significant provisional QTL on chromosome 17 for Day 1 HP latency in mice receiving ethanol. An additional highly suggestive QTL was present on chromosome 9 for the difference in pre- and post-ethanol thermal nociception. Candidate genes within QTL support intervals were provisionally identified using HP phenotypic correlations to transcriptomic database, expression QTL analysis, and other bioinformatics inquiries. The combined behavioral and bioinformatic analyses yielded strong ethanol analgesia candidate genes, specifically Myo6. Thus, the results of this genetic study of ethanol-induced analgesia in BXD mouse strains may contribute significantly to our understanding of the molecular basis for individual variation in the analgesic response to acute ethanol.

Pain in alcohol use disorder: Evaluating effects of childhood trauma, perceived stress, and psychological comorbidity

The relationship between pain and alcohol use disorder (AUD) is complex and bidirectional. The current study examines risk factors for pain in a large comprehensively phenotyped sample including individuals from across the spectrum of alcohol use and misuse. Participants (n = 1101) were drawn from the National Institute on Alcohol Abuse and Alcoholism Natural History Protocol and included treatment-seeking AUD inpatients (AUD+Tx, n = 369), individuals with AUD not seeking treatment (AUD+, n = 161), and individuals without AUD (AUD-, n = 571). General linear models were utilized to test the effects of AUD status, history of childhood trauma exposure, perceived stress, and psychological comorbidity on daily percent time in pain, as well as change in daily percent time in pain across the inpatient stay in AUD+Tx individuals. Overall, 60.2% individuals reported any pain, with a significantly higher prevalence in the AUD+Tx group (82.1%) compared to the AUD+ (56.5%) and AUD- (47.1%) groups. Daily percent time in pain was also highest in the AUD+Tx group (30.2%) and was further increased in those with a history of childhood abuse and comorbid posttraumatic stress disorder (PTSD). Years of heavy drinking and craving were also associated with increased percent time in pain in the AUD+Tx group. Percent time in pain decreased following acute withdrawal in the AUD+Tx group but plateaued around 25% just prior to discharge. Individuals seeking inpatient treatment for AUD, especially those with a history of childhood trauma and/or comorbid PTSD, report greater percent time in pain compared to those not seeking treatment and those without AUD. The prolonged experience of pain in abstinent AUD inpatients after the resolution of acute withdrawal may signal the early stages of protracted withdrawal. Integrative treatments targeting pain and other symptoms of protracted withdrawal may be effective in improving overall function in people with severe AUD.

Surgical incision pain induced an increase in alcohol consumption in mice

INTRODUCTION

Large population-based studies have suggested a link between increased alcohol use and reduced pain. In addition, these studies suggest that higher levels of pain intensity are associated with an increase in alcohol consumption and rates of hazardous drinking which potentiates the risk of developing alcohol use disorders (AUD). The mechanisms and determinants of the alcohol-pain interaction can be studied in preclinical studies.

METHODS

The overall goal of this study is to use animal models to explore the impact of acute postoperative pain on alcohol intake. To achieve this, we characterized the timeline and levels of alcohol intake and preference in mice after laparotomy in the 2-bottle choice paradigm.

RESULTS

Our results show that laparotomy surgery increased alcohol intake and preference in male mice but not females in the 2-bottle choice and 3-bottle choice assays. In addition, ketoprofen administration blocked the increase in alcohol consumption in male mice after laparotomy. We also found that changes in alcohol initial sensitivity and acute functional tolerance, using loss of righting reflex (LORR) response, occur after surgery in mice.

CONCLUSION

Taken together, these findings suggests that sex, pain and alcohol sensitivity-related factors may modulate the relationship between alcohol consumption and pain.

Nociplastic Pain and Pain-Motivated Drinking in Alcohol Use Disorder

Heavy chronic alcohol use may produce pain amplification through neurochemical and neuroplastic changes at multiple levels of the nervous system. Similar changes are thought to underlie nociplastic pain. The American College of Rheumatology Fibromyalgia Survey has been used as a surrogate for nociplastic pain, including among individuals with alcohol use disorder (AUD). However, studies linking nociplastic pain to pain-motivated drinking are lacking. The present study aimed to determine if nociplastic pain is associated with pain-motivated drinking in AUD. To achieve this aim, a new scale-the Pain-Motivated Drinking Scale (PMDS)-was developed to measure how often participants were motivated by pain to drink alcohol. Measurement properties of this new scale were determined, including its factor structure, internal consistency reliability, and construct validity. In this cross-sectional observational study, participants with AUD (n = 138) were consecutively recruited from the patient pool at an academic addiction treatment facility. Seventy-two percent (95, 72.0%) reported they drank alcohol "to get relief from physical pain" at least some of the time, and over forty-two percent (56, 42.4%) reported pain relief motivated their drinking at least half of the time. PMDS had a single-factor structure, strong internal consistency reliability, and construct validity. A multiple hierarchical linear regression was run to determine if nociplastic pain was associated with pain-motivated drinking. Nociplastic pain was associated with PMDS even after controlling for potential confounders and pain severity. These findings suggest nociplastic pain is uniquely associated with pain-motivated drinking in AUD. PERSPECTIVE: Nociplastic pain is independently associated with pain-motivated drinking in alcohol use disorder (AUD). The Pain-Motivated Drinking Scale (PMDS) is a new scale to measure how often people drink to cope with pain. PMDS has promising psychometric properties. Nociplastic pain may be uniquely associated with pain-motivated drinking in AUD.

Alcohol Use Disorder and Chronic Pain: An Overlooked Epidemic

Alcohol use disorder (AUD) and chronic pain disorders are pervasive, multifaceted medical conditions that often co-occur. However, their comorbidity is often overlooked, despite its prevalence and clinical relevance. Individuals with AUD are more likely to experience chronic pain than the general population. Conversely, individuals with chronic pain commonly alleviate their pain with alcohol, which may escalate into AUD. This narrative review discusses the intricate relationship between AUD and chronic pain. Based on the literature available, the authors present a theoretical model explaining the reciprocal relationship between AUD and chronic pain across alcohol intoxication and withdrawal. They propose that the use of alcohol for analgesia rapidly gives way to acute tolerance, triggering the need for higher levels of alcohol consumption. Attempts at abstinence lead to alcohol withdrawal syndrome and hyperalgesia, increasing the risk of relapse. Chronic neurobiological changes lead to preoccupation with pain and cravings for alcohol, further entrenching both conditions. To stimulate research in this area, the authors review methodologies to improve the assessment of pain in AUD studies, including self-report and psychophysical methods. Further, they discuss pharmacotherapies and psychotherapies that may target both conditions, potentially improving both AUD and chronic pain outcomes simultaneously. Finally, the authors emphasize the need to manage both conditions concurrently, and encourage both the scientific community and clinicians to ensure that these intertwined conditions are not overlooked given their clinical significance.

Pain and Hazardous Alcohol Use in Veterans in Primary Care: The Role of Affective Pain Interference and Alcohol Pain-Coping Perceptions

Chronic pain and unhealthy alcohol use commonly co-occur and are associated with negative health outcomes. Veterans may be particularly vulnerable to these conditions, yet limited research has examined factors involved in their co-occurrence. This cross-sectional study aimed to examine the role of affective pain interference and alcohol pain-coping perceptions in the relationship between pain and hazardous alcohol use. As informed by the catastrophizing, anxiety, negative urgency, and expectancy model, we hypothesized that the relationship between pain and hazardous alcohol consumption is mediated by affective pain interference and stronger among those with greater perceptions that alcohol helps cope with pain. Participants were 254 VA primary care patients (87.8% male, Mage = 64.03, 76.4% White) with a history of chronic musculoskeletal pain, past-year alcohol use, and past-week pain. Veterans completed a mailed survey including measures of pain, affective pain interference, alcohol pain-coping perceptions, and hazardous alcohol use. Hypotheses were tested with regression models and PROCESS macros. As hypothesized, affective pain interference mediated the pain-hazardous alcohol use association. Contrary to hypotheses, results showed no moderating effect of alcohol pain-coping perceptions. Findings partially support relationships among theorized constructs and suggest that for Veterans with co-occurring pain and alcohol use it may be important to target pain-related affective interference and perceptions that alcohol helps cope with pain. PERSPECTIVE: This article presents a test of factors involved in the pain and alcohol relationship, as informed by the CANUE model. Findings suggest that for Veterans with co-occurring pain and past-year alcohol use, it may be important to target pain-related affective interference and perceptions that alcohol helps cope with pain.

Alcohol consumption and opioid craving among chronic pain patients prescribed long-term opioid therapy

BACKGROUND

Concurrent use of alcohol with opioids is common among chronic pain patients, heightening the risk for disordered opioid use and overdose, yet the relationship between alcohol consumption and opioid craving among chronic pain patients remains largely unexplored. Here we examined the relationship between alcohol consumption and opioid craving among chronic pain patients on long-term opioid therapy.

METHODS

A cross-sectional study was conducted with 335 chronic pain patients on long-term opioid therapy. Participants completed the Timeline Followback to assess alcohol consumption, as well as measures of opioid craving, pain severity, and pain interference. Linear regression analyses examined the relationship between alcohol consumption and opioid craving, controlling for pain severity, pain interference, and opioid misuse severity.

RESULTS

Alcohol consumption (total number of drinks and amount consumed in one sitting) was positively associated with opioid craving (p < 0.001 and p = 0.005, respectively). Pain severity did not predict opioid craving. The relationship between alcohol consumption and opioid craving remained significant after controlling for pain severity, pain interference, and opioid misuse severity.

CONCLUSION

Alcohol consumption is linked with more severe opioid craving among chronic pain patients prescribed long-term opioid therapy. Patients receiving opioid analgesics should be carefully screened for co-use of alcohol.

Mechanisms of pain in aging and age-related conditions: Focus on caregivers

Pain is a complex, subjective experience that can significantly impact quality of life, particularly in aging individuals, by adversely affecting physical and emotional well-being. Whereas acute pain usually serves a protective function, chronic pain is a persistent pathological condition that contributes to functional deficits, cognitive decline, and emotional disturbances in the elderly. Despite substantial progress that has been made in characterizing age-related changes in pain, complete mechanistic details of pain processing mechanisms in the aging patient remain unknown. Pain is particularly under-recognized and under-managed in the elderly, especially among patients with Alzheimer's disease (AD), Alzheimer's disease-related dementias (ADRD), and other age-related conditions. Furthermore, difficulties in assessing pain in patients with AD/ADRD and other age-related conditions may contribute to the familial caregiver burden. The purpose of this article is to discuss the mechanisms and risk factors for chronic pain development and persistence, with a particular focus on age-related changes. Our article also highlights the importance of caregivers working with aging chronic pain patients, and emphasizes the urgent need for increased legislative awareness and improved pain management in these populations to substantially alleviate caregiver burden.

Self-medication of pain and discomfort with alcohol and other substances by people with HIV infection and substance use disorder: preliminary findings from a secondary analysis

There is a limited literature regarding factors associated with self-medication of pain and discomfort using alcohol, non-prescription substances or overuse of prescription medications among people living with Human Immunodeficiency Virus (HIV). This cross-sectional analysis used data from the Boston ARCH Cohort among participants with HIV infection and a history of alcohol or other substance use. Among 248 participants, 37% were female, 50% Black, 25% Latinx; 36% reported fair to poor health and 89% had CD4 cell counts >200/mm3. Half reported self-medication and of those, 8.8% reported doing so only with alcohol, 48.8% only with other substances and 42.4% with both alcohol and other substances. Those reporting self-medication were significantly (p < .05) younger (mean 47 vs 50 years), less employed (11% vs 21%), and less likely to have HIV viral suppression (60% vs. 80%). Depression, anxiety, and HIV symptoms were associated with significantly greater odds of self-medicating, as were substance dependence, recent injection substance use, heavy alcohol use, cocaine use, opioid use, sedative use, and cannabis use. Self-medication, highly prevalent and associated with worse mental health symptoms, greater substance use, and lesser HIV disease control, should be explored by HIV clinicians caring for people who use substances.

Eating habits and the desire to eat healthier among patients with chronic pain: a registry-based study

Healthcare professionals often meet pain patients with a poor nutritional status such as obesity, unhealthy dietary behaviors, and a suboptimal dietary intake. A poor nutritional status may play a significant role in the occurrence, development, and prognosis of chronic pain. This study investigated eating habits in a specialized pain rehabilitation center using data (N = 2152) from the Swedish quality registry for pain rehabilitation during the period 2016-2021. Patients answered a lifestyle questionnaire regarding their eating habits and desire to modify their lifestyle. The mean (SD) patient age was 46.1 (14.6) years, with 24.8% classified as obese. Suboptimal eating habits included irregular mealtimes (27.2%), weekly consumption of fast-food (20.3%) and nearly daily consumption of confectionery (33.3%). Approximately 20% (n = 426) reported a desire to eat healthier. Frequent confectionery intake (Odds ratio [OR] 1.23, 95% Confidence Interval (CI) 1.04-1.47) and fast-food consumption (OR 1.58, 95% CI 1.24-2.02) increased the likelihood to desire healthier eating. Younger patients (18-29 years), those classified as obese, and those with more extended spatial pain were more likely to express a desire to eat healthier. Eating habits should be addressed in pain management and interdisciplinary pain rehabilitation teams are encouraged to provide nutritional care tailored to the patient's needs.

Pleiotropy and genetically inferred causality linking multisite chronic pain to substance use disorders

Individuals suffering from chronic pain develop substance use disorders (SUDs) more often than others. Understanding the shared genetic influences underlying the comorbidity between chronic pain and SUDs will lead to a greater understanding of their biology. Genome-wide association statistics were obtained from the UK Biobank for multisite chronic pain (MCP, Neffective = 387,649) and from the Million Veteran Program and the Psychiatric Genomics Consortium meta-analyses for alcohol use disorder (AUD, Neffective = 296,974), cannabis use disorder (CanUD, Neffective = 161,053), opioid use disorder (OUD, Neffective = 57,120), and problematic tobacco use (PTU, Neffective = 270,120). SNP-based heritability was estimated for each of the traits and genetic correlation (rg) analyses were performed to assess MCP-SUD pleiotropy. Bidirectional Mendelian Randomization analyses evaluated possible causal relationships. Finally, to identify and characterize individual loci, we performed a genome-wide pleiotropy analysis and a brain-wide analysis using imaging phenotypes available from the UK Biobank. MCP was positively genetically correlated with AUD (rg = 0.26, p = 7.55 × 10-18), CanUD (rg = 0.37, p = 8.21 × 10-37), OUD (rg = 0.20, p = 1.50 × 10-3), and PTU (rg = 0.29, p = 8.53 × 10-12). Although the MR analyses supported bi-directional relationships, MCP had larger effects on AUD (pain-exposure: beta = 0.18, p = 8.21 × 10-4; pain-outcome: beta = 0.07, p = 0.018), CanUD (pain-exposure: beta = 0.58, p = 2.70 × 10-6; pain-outcome: beta = 0.05, p = 0.014) and PTU (pain-exposure: beta = 0.43, p = 4.16 × 10-8; pain-outcome: beta = 0.09, p = 3.05 × 10-6) than the reverse. The genome-wide analysis identified two SNPs pleiotropic between MCP and all SUD investigated: IHO1 rs7652746 (ppleiotropy = 2.69 × 10-8), and CADM2 rs1248857 (ppleiotropy = 1.98 × 10-5). In the brain-wide analysis, rs7652746 was associated with multiple cerebellum and amygdala imaging phenotypes. When analyzing MCP pleiotropy with each SUD separately, we found 25, 22, and 4 pleiotropic variants for AUD, CanUD, and OUD, respectively. To our knowledge, this is the first large-scale study to provide evidence of potential causal relationships and shared genetic mechanisms underlying MCP-SUD comorbidity.

Deficits in proactive avoidance and neural responses to drinking motives in problem drinkers

Physical pain and negative emotions represent two distinct drinking motives that contribute to harmful alcohol use. Proactive avoidance which can reduce problem drinking in response to these motives appears to be impaired in problem drinkers. However, proactive avoidance and its underlying neural deficits have not been assessed experimentally. How these deficits inter-relate with drinking motives to influence alcohol use also remains unclear. The current study leveraged neuroimaging data collected in forty-one problem and forty-one social drinkers who performed a probabilistic learning go/nogo task that involved proactive avoidance of painful outcomes. We characterized the regional brain responses to proactive avoidance and identified the neural correlates of drinking to avoid physical pain and negative emotions. Behavioral results confirmed problem drinkers' proactive avoidance deficits in learning rate and performance accuracy, both which were associated with greater alcohol use. Imaging findings in problem drinkers showed that negative emotions as a drinking motive predicted attenuated right insula activation during proactive avoidance. In contrast, physical pain motive predicted reduced right putamen response. These regions' activations as well as functional connectivity with the somatomotor cortex also demonstrated a negative relationship with drinking severity and positive relationship with proactive avoidance performance. Path modeling further delineated the pathways through which physical pain and negative emotions, along with alcohol use severity, influenced the neural and behavioral measures of proactive avoidance. Taken together, the current findings provide experimental evidence for proactive avoidance deficits in problem drinkers and establish the link between their neural underpinnings and alcohol misuse.

Impact of Environment on Pain among the Working Poor: Making Use of Random Forest-Based Stratification Tool to Study the Socioecology of Pain Interference

Pain interferes with one's work and social life and, at a personal level, daily activities, mood, and sleep quality. However, little research has been conducted on pain interference and its socioecological determinants among the working poor. Noting the clinical/policy decision needs and the technical challenges of isolating the intricately interrelated socioecological factors' unique contributions to pain interference and quantifying the relative contributions of each factor in an interpretable manner to inform clinical and policy decision-making, we deployed a novel random forest algorithm to model and quantify the unique contribution of a diverse ensemble of environmental, sociodemographic, and clinical factors to pain interference. Our analyses revealed that features representing the internal built environment of the working poor, such as the size of the living space, air quality, access to light, architectural design conducive to social connection, and age of the building, were assigned greater statistical importance than other more commonly examined predisposing factors for pain interference, such as age, occupation, the severity and locations of pain, BMI, serum blood sugar, and blood pressure. The findings were discussed in the context of their benefit in informing community pain screening to target residential areas whose built environment contributed most to pain interference and informing the design of intervention programs to minimize pain interference among those who suffered from chronic pain and showed specific characteristics. The findings support the call for good architecture to provide the spirit and value of buildings in city development.

Adolescent Alcohol Exposure Produces Sex-Specific Long-term Hyperalgesia via Changes in Central Amygdala Circuit Function

BACKGROUND

Exposure to alcohol during adolescence produces many effects that last well into adulthood. Acute alcohol use is analgesic, and people living with pain report drinking alcohol to reduce pain, but chronic alcohol use produces increases in pain sensitivity.

METHODS

We tested the acute and lasting effects of chronic adolescent intermittent ethanol (AIE) exposure on pain-related behavioral and brain changes in male and female rats. We also tested the long-term effects of AIE on synaptic transmission in midbrain (ventrolateral periaqueductal gray [vlPAG])-projecting central amygdala (CeA) neurons using whole-cell electrophysiology. Finally, we used circuit-based approaches (DREADDs [designer receptors exclusively activated by designer drugs]) to test the role of vlPAG-projecting CeA neurons in mediating AIE effects on pain-related outcomes.

RESULTS

AIE produced long-lasting hyperalgesia in male, but not female, rats. Similarly, AIE led to a reduction in synaptic strength of medial CeA cells that project to the vlPAG in male, but not female, rats. Challenge with an acute painful stimulus (i.e., formalin) in adulthood produced expected increases in pain reactivity, and this effect was exaggerated in male rats with a history of AIE. Finally, CeA-vlPAG circuit activation rescued AIE-induced hypersensitivity in male rats.

CONCLUSIONS

Our findings are the first, to our knowledge, to show long-lasting sex-dependent effects of adolescent alcohol exposure on pain-related behaviors and brain circuits in adult animals. This work has implications for understanding the long-term effects of underage alcohol drinking on pain-related behaviors in humans.

Preoperative Factors Associated With Worse PROMIS Pain Interference 2 Years After Hand and Wrist Surgery

BACKGROUND

The purpose of this study was to identify preoperative factors associated with worse postoperative Patient-Reported Outcomes Measurement Information System (PROMIS) pain interference (PI) scores 2 years after hand and wrist surgery. We hypothesized that older age, more comorbidities, increased substance use, and lower socioeconomic status would correlate with worse 2-year PROMIS PI scores.

METHODS

This study was a retrospective review of prospectively acquired data on 253 patients. Surveys were administered within 1 week of surgery and 2 years postoperatively. Bivariate and multivariable analyses were conducted to identify significant predictors of worse 2-year PROMIS PI scores and change in PROMIS PI scores.

RESULTS

Older age, higher body mass index, more comorbidities, lower preoperative expectations, more prior surgeries, unemployment, smoking, higher American Society of Anesthesiologists (ASA) score, and multiple other socio-demographic factors were correlated with worse 2-year PROMIS PI scores (P ≤ .018). Similar factors were also correlated with less improvement in 2-year PROMIS PI scores (P ≤ .048). Worse scores on all preoperative patient-reported outcome measures correlated with worse 2-year PROMIS PI scores (P ≤ .007). Multivariable analysis identified smoking history, less frequent alcohol consumption, worse preoperative PROMIS social satisfaction and Numeric Pain Scale whole body scores, and higher ASA scores as independent predictors of worse 2-year PROMIS PI. The same factors in addition to better baseline PROMIS PI were predictive of less improvement in 2-year PROMIS PI.

CONCLUSION

Numerous preoperative factors were predictive of worse postoperative 2-year PROMIS PI and less improvement in 2-year PROMIS PI for patients undergoing hand and wrist surgery.

Neural and Psychosocial Mechanisms Underlying Alcohol Use and Pain Interactions: Overview of Current Evidence and Future Directions

Purpose of Review

A growing body of research indicates bidirectional associations between alcohol use and pain. In this review, we highlight common neural and psychosocial mechanisms underlying pain and alcohol use and identify current gaps in the literature regarding alcohol/pain interactions. We also suggest future directions for the field moving forward, including more nuanced conceptualization of alcohol's negative reinforcing effects in the context of pain, broader use of clinically-relevant experimental pain induction modalities, and characterization of age, biological sex, gender, race, and ethnicity as moderators of pain/alcohol interactions.

Recent Findings

Acute alcohol intake has analgesic and negative-reinforcing effects in the context of pain, and chronic heavy alcohol use appears to increase risk for development of chronic pain. At the same time, pain, both acute and chronic, acts as a proximal antecedent for alcohol use and is associated with relapse risk for individuals in recovery from alcohol use disorder.

Summary

Although the links between alcohol use and pain are increasingly appreciated, significant gaps in understanding remain and systematic study of alcohol/pain interactions at all levels, including basic, preclinical, translational, and interventional, is needed.

Microglial P2X4 receptors are essential for spinal neurons hyperexcitability and tactile allodynia in male and female neuropathic mice

In neuropathic pain, recent evidence has highlighted a sex-dependent role of the P2X4 receptor in spinal microglia in the development of tactile allodynia following nerve injury. Here, using internalization-defective P2X4mCherryIN knockin mice (P2X4KI), we demonstrate that increased cell surface expression of P2X4 induces hypersensitivity to mechanical stimulations and hyperexcitability in spinal cord neurons of both male and female naive mice. During neuropathy, both wild-type (WT) and P2X4KI mice of both sexes develop tactile allodynia accompanied by spinal neuron hyperexcitability. These responses are selectively associated with P2X4, as they are absent in global P2X4KO or myeloid-specific P2X4KO mice. We show that P2X4 is de novo expressed in reactive microglia in neuropathic WT and P2X4KI mice of both sexes and that tactile allodynia is relieved by pharmacological blockade of P2X4 or TrkB. These results show that the upregulation of P2X4 in microglia is crucial for neuropathic pain, regardless of sex.

Lifestyle changes are burdensome with my body broken by pain and obesity: patients' perspectives after pain rehabilitation

BACKGROUND

Despite the existing evidence regarding the interrelated relationship between pain and obesity, knowledge about patients' perspectives of this relationship is scarce, especially from patients with chronic pain and obesity after completing Interdisciplinary Pain Rehabilitation Program (IPRP).

AIMS

This qualitative study expands the understanding of patients' perspectives on how chronic pain and obesity influence each other and how the two conditions affect the ability to make lifestyle changes.

METHOD

A purposive sample of patients with Body Mass Index (BMI) ≥ 30 kg/m2 and who had completed an IPRP were recruited for individual semi-structured interviews. The transcribed interviews were analysed using latent content analysis and a pattern of theme and categories was constructed based on the participants' perspectives.

RESULTS

Sixteen patients (aged 28-63 years, 11 female, BMI 30-43 kg/m2) shared their experiences of chronic pain, obesity and lifestyle changes after IPRP. The analysis revealed one overall theme (lifestyle changes are burdensome with a body broken by both pain and obesity) and four categories (pain disturbing days and nights worsens weight control, pain-related stress makes lifestyle changes harder, a painful and obese body intertwined with negative emotions and the overlooked impact of obesity on chronic pain). Most participants perceived that their pain negatively impacted their obesity, but they were uncertain whether their obesity negatively impacted their pain. Nevertheless, the participants desired and struggled to make lifestyle changes.

CONCLUSION

After IPRP, patients with chronic pain and obesity perceived difficulties with self-management and struggles with lifestyle changes. They experienced a combined burden of the two conditions. Their perspective on the unilateral relationship between pain and obesity differed from the existing evidence. Future tailored IPRPs should integrate nutritional interventions and address the knowledge gaps as well.

Temporal associations between use of psychoactive substances and somatic symptoms in the daily lives of people with fibromyalgia

OBJECTIVE

Consumption of psychoactive substances-alcohol, nicotine, caffeine, opioids, and cannabis-is common among people with fibromyalgia. Associations between the use of substances and somatic symptoms could reflect efforts to cope with symptoms, aggravation or alleviation of symptoms after the use of substances, or a combination of these. To date, no study has provided insight into temporal associations between the consumption of psychoactive substances and fluctuations in somatic symptoms. We explored whether changes in ratings of pain and fatigue (mental and physical) predicted the later use of psychoactive substances or vice versa (substance use predicting later change in symptoms).

DESIGN

Micro-longitudinal design.

SETTING/SUBJECTS

Fifty adults (88% female, 86% White, mean age of 44.9 years) with fibromyalgia.

METHODS

Participants completed ecological momentary assessments of substance use, pain intensity, and physical/mental fatigue 5 times per day for 8 days.

RESULTS

Results of multilevel models indicated that momentary increases in fatigue showed a consistent association with greater odds of later use of psychoactive substances, whereas momentary increases in pain were related to lower odds of later cannabis and nicotine use and higher odds of later alcohol use. Only nicotine use predicted later mental fatigue.

CONCLUSION

Findings highlight the importance of individualized interventions for symptom management or problems related to the use of psychoactive substances. We observed that although somatic symptoms predicted later use of substances, use of substances did not show appreciable effects with regard to alleviating somatic symptoms in people with fibromyalgia.

Opioid coping motives and pain intensity among adults with chronic low back pain: associations with mood, pain reactivity, and opioid misuse

Chronic low back pain (CLBP) is a significant public health problem that is associated with opioid misuse and use disorder. Despite limited evidence for the efficacy of opioids in the management of chronic pain, they continue to be prescribed and people with CLBP are at increased risk for misuse. Identifying individual difference factors involved in opioid misuse, such as pain intensity as well as reasons for using opioids (also known as motives), may provide pertinent clinical information to reduce opioid misuse among this vulnerable population. Therefore, the aims of the current study were to examine the relationships between opioid motives-to cope with pain-related distress and pain intensity, in terms of anxiety, depression, pain catastrophizing, pain-related anxiety, and opioid misuse among 300 (Mage= 45.69, SD = 11.17, 69% female) adults with CLBP currently using opioids. Results from the current study suggest that both pain intensity and motives to cope with pain-related distress with opioids were associated with all criterion variables, but the magnitude of variance explained by coping motives was larger than pain intensity in terms of opioid misuse. The present findings provide initial empirical evidence for the importance of motives to cope with pain-related distress with opioids and pain intensity in efforts to better understand opioid misuse and related clinical correlates among adults with CLBP.

Does treating pain with alcohol affect drinking reduction among women with HIV enrolled in a clinical trial of naltrexone?

BACKGROUND

Many women living with HIV (WLWH) experience pain. Alcohol use with the intent to treat pain could lead to hazardous drinking and difficulty in reducing drinking. Naltrexone acts on opioid receptors important for pain regulation and is an approved treatment for alcohol use disorder. In this secondary analysis of a randomized double-blind placebo-controlled naltrexone clinical trial, the goals were to (1) compare alcohol reduction between women who drank to treat pain and those who did not and (2) examine differences in alcohol reduction by both drinking intention and treatment arm.

METHODS

Women living with HIV (N = 194, mean age 48.3 years, 83% non-Hispanic Black, 11% Hispanic) with hazardous drinking (>7 drinks/week) were randomized to receive daily treatment with naltrexone 50 mg or placebo for 4 months. Study visits occurred at baseline and 2, 4, and 7 months (posttreatment). The number of drinks/week was measured using the Timeline Follow Back. Use of alcohol to treat pain was self-reported. Participants were categorized as using alcohol to treat pain or not and in the naltrexone or placebo group. Chi-square, t-test, MANOVA, and sequential mixed effects models were used to determine group differences in demographic factors, mean/drinks per week, and percent change in mean drinks/week at baseline and each follow-up visit.

RESULTS

There was a consistent decrease in drinking throughout the study. There was not a significant difference in mean drinks/week at any point in the study between women who used alcohol to treat pain and those who did not. When considering treatment arm, at 2 months only those who did not use alcohol to treat pain in the naltrexone group had a significantly lower mean drinks/week than the other groups (p = 0.007); all groups had similar decreases in drinking from 4 months onward.

CONCLUSION

In the naltrexone group, WLWH who drank to treat pain reduced their alcohol consumption more slowly than WLWH who did not drink to treat pain. Replication of these findings would suggest that alcohol treatment guidelines should address pain as a factor in drinking outcomes.

Chronic alcohol induced mechanical allodynia by promoting neuroinflammation: A mouse model of alcohol-evoked neuropathic pain

BACKGROUND AND PURPOSE

Chronic pain is considered a key factor contributing to alcohol use disorder (AUD). The mechanisms responsible for chronic pain associated with chronic alcohol consumption are unknown. We evaluated the development of chronic pain in a mouse model of alcohol dependence and investigate the role of neuroinflammation.

EXPERIMENTAL APPROACH

The chronic-intermittent ethanol two-bottle choice CIE-2BC paradigm generates three groups: alcohol-dependent with escalating alcohol intake, nondependent (moderate drinking) and alcohol-naïve control male and female mice. We measured mechanical allodynia during withdrawal and after the last voluntary drinking. Immunoblotting was used to evaluate the protein levels of IBA-1, CSFR, IL-6, p38 and ERK2/1 in spinal cord tissue of dependent and non-dependent animals.

KEY RESULTS

We found significant escalation of drinking in the dependent group in male and female compared with the non-dependent group. The dependent group developed mechanical allodynia during 72 h of withdrawal, which was completely reversed after voluntary drinking. We observed an increased pain hypersensitivity compared with the naïve in 50% of non-dependent group. Increased IBA-1 and CSFR expression was observed in spinal cord tissue of both hypersensitivity-abstinence related and neuropathy-alcohol mice, and increased IL-6 expression and ERK1/2 activation in mice with hypersensitivity-related to abstinence, but not in mice with alcohol-evoked neuropathic pain.

CONCLUSIONS AND IMPLICATIONS

The CIE-2BC model induces two distinct pain conditions specific to the type of ethanol exposure: abstinence-related hypersensitivity in dependent mice and alcohol-evoked neuropathic pain in about a half of the non-dependent mice.

Identifying and addressing patient substance use: a survey of chiropractic clinicians

BACKGROUND

Chiropractors commonly encounter patients who present for spine pain with parallel substance use. There is currently no widespread training within the chiropractic profession to prepare chiropractors to recognize and address substance use in clinical practice. The purpose of this study was to examine chiropractors' confidence, self-perceptions, and interest in education associated with identifying and addressing patient substance use.

METHODS

A 10-item survey was developed by the authors. The survey addressed chiropractors' assessment of their training, experiences, and educational interest/needs regarding identifying and addressing patient substance use. The survey instrument was uploaded to Qualtrics and was electronically distributed to chiropractic clinicians at active and accredited English-speaking Doctor of Chiropractic degree programs (DCPs) in the United States.

RESULTS

A total of 175 individual survey responses were returned from a total of 276 eligible participants (63.4% response rate) from 16 out of 18 active and accredited English-speaking DCPs (88.8% of DCPs) in the United States. Nearly half of respondents strongly disagreed or disagreed (n = 77, 44.0%) that they were confident in their ability to identify patients who misuse prescription medication. The majority of respondents (n = 122, 69.7%) indicated that they did not have an established referral relationship with local clinical providers who provide treatment for individuals who use drugs or misuse alcohol or prescription medications. Most respondents strongly agreed or agreed (n = 157, 89.7%) that they would benefit from participating in a continuing education course on topics related to patients who use drugs or misuse alcohol or prescription medications.

CONCLUSIONS

Chiropractors indicated a need for training to help them identify and address patient substance use. There is a demand among chiropractors to develop clinical care pathways for chiropractic referrals and collaboration with health care professionals who provide treatment for individuals who use drugs or misuse alcohol or prescription medications.

Sex-specific biobehavioral regulation of persistent inflammatory pain by alcohol

BACKGROUND

Although a large percentage of chronic pain patients consume alcohol to manage their pain, there is a significant gap in knowledge regarding the mechanisms underlying the antinociceptive effects of alcohol.

METHODS

To determine the longitudinal analgesic effects of alcohol, we utilized the complete Freund's adjuvant (CFA) model of inflammatory pain in adult female and male Wistar rats. Both somatic and negative motivational aspects of pain were measured using the electronic von Frey (mechanical nociception) system, thermal probe test (thermal nociception), and mechanical conflict avoidance task (pain avoidance-like behavior). Tests were conducted at baseline and 1 and 3 weeks following intraplantar CFA or saline administration. At both time points post-CFA, animals were treated with each of three doses of alcohol (intraperitoneal; 0, 0.5, and 1.0 g/kg) over separate days in a Latin square design.

RESULTS

Alcohol produced dose-dependent mechanical analgesia and antihyperalgesia in females but only antihyperalgesia in males. Although alcohol continued to attenuate CFA-induced decreases in both thermal and mechanical nociceptive thresholds between 1 and 3 weeks post-CFA, it appeared less effective at increasing thresholds 3 weeks after CFA induction.

CONCLUSIONS

These data suggest that individuals may develop tolerance to alcohol's ability to alleviate both somatic and negative motivational symptoms of chronic pain over time. We also discovered sex-specific neuroadaptations in protein kinase A-dependent phosphorylation of GluR1 subunits and extracellular signal-regulated kinase (ERK 1/2) phosphorylation in nociceptive brain centers of animals receiving an alcohol challenge 1 week post-CFA. Together, these findings illustrate a sex-specific regulation of behavioral and neurobiological indices of persistent pain by alcohol.

Self-management with alcohol over lifespan: psychological mechanisms, neurobiological underpinnings, and risk assessment

Self-management includes all behavioural measures and cognitive activities aimed at coping with challenges arising throughout the lifespan. While virtually all of these challenges can be met without pharmacological means, alcohol consumption has long been instrumentalized as a supporting tool to help coping with problems arising selectively at adolescence, adulthood, and ageing. Here, we present, to our knowledge, the first systematic review of alcohol instrumentalization throughout lifespan. We searched MEDLINE, Google Scholar, PsycINFO and CINAHL (from Jan, 1990, to Dec, 2022) and analysed consumption patterns, goals and potential neurobiological mechanisms. Evidence shows a regular non-addictive use of alcohol to self-manage developmental issues during adolescence, adulthood, and ageing. Alcohol is selectively used to overcome problems arising from dysfunctional personality traits, which manifest in adolescence. A large range of psychiatric disorders gives rise to alcohol use for the self-management of distinct symptoms starting mainly in adulthood. We identify those neuropharmacological effects of alcohol that selectively serve self-management under specific conditions. Finally, we discuss the adverse effects and associated risks that arise from the use of alcohol for self-management. Even well-controlled alcohol use adversely impacts health. Based on these findings, we suggest the implementation of an entirely new view. Health policy action may actively embrace both sides of the phenomenon through a personalized informed use that allows for harm-controlled self-management with alcohol.

"I Was Literally Just Not Myself": How Chronic Pain Changes Multiple Frames of Identity

Though experienced by more than 1 in 5 (50 million) American adults, chronic pain is invisible, subjective, difficult to communicate, and often stigmatized. When faced with a serious injury or ongoing illness, individuals create an "illness identity" by modifying their goals and expectations for the future, adapting to impairments, and understanding new emotional reactions. The current, two-phase study uses the communication theory of identity (CTI) to explore the process of illness identity adoption in the context of chronic pain, which may be different than for more understood, less stigmatized illnesses. A focus group was conducted (N = 6), from which interview protocol were created. Interview participants (N = 23) described specific differences between their pre- and post-pain selves within three identity frames: personal, relational, and enacted. Within each frame, several sub-themes of pain-related identity changes are identified, as well how they were communicated and how they subsequently influenced communication. Additionally, three pain-related identity gaps, or ways in which two identity frames contradict each other, were identified, all created explicitly because of the onset of chronic pain: personal-enacted, personal-relational, and personal-communal. Theoretical contributions include using CTI to outline the illness identity adoption process in the context of chronic pain, identifying unique identity gaps created by this relatively widespread condition. Practically, understanding pain-related identity outcomes can help pain patients make sense of and manage their situation, and de-stigmatize the chronic pain experience.

Adolescent ethanol drinking promotes hyperalgesia, neuroinflammation and serotonergic deficits in mice that persist into adulthood

Adolescent alcohol use can permanently alter brain function and lead to poor health outcomes in adulthood. Emerging evidence suggests that alcohol use can predispose individuals to pain disorders or exacerbate existing pain conditions, but the underlying neural mechanisms are currently unknown. Here we report that mice exposed to adolescent intermittent access to ethanol (AIE) exhibit increased pain sensitivity and depressive-like behaviors that persist for several weeks after alcohol cessation and are accompanied by elevated CD68 expression in microglia and reduced numbers of serotonin (5-HT)-expressing neurons in the dorsal raphe nucleus (DRN). 5-HT expression was also reduced in the thalamus, anterior cingulate cortex (ACC) and amygdala as well as the lumbar dorsal horn of the spinal cord. We further demonstrate that chronic minocycline administration after AIE alleviated hyperalgesia and social deficits, while chemogenetic activation of microglia in the DRN of ethanol-naïve mice reproduced the effects of AIE on pain and social behavior. Chemogenetic activation of microglia also reduced tryptophan hydroxylase 2 (Tph2) expression and was negatively correlated with the number of 5-HT-immunoreactive cells in the DRN. Taken together, these results indicate that microglial activation in the DRN may be a primary driver of pain, negative affect, and 5-HT depletion after AIE.

Medication overuse headache and substance use disorder: A comparison based on basic research and neuroimaging

It has yet to be determined whether medication overuse headache (MOH) is an independent disorder or a combination of primary headache and substance addiction. To further explore the causes of MOH, we compared MOH with substance use disorder (SUD) in terms of the brain regions involved to draw more targeted conclusions. In this review, we selected alcohol use disorder (AUD) as a representative SUD and compared MOH and AUD from two aspects of neuroimaging and basic research. We found that in neuroimaging studies, there were many overlaps between AUD and MOH in the reward circuit, but the extensive cerebral cortex damage in AUD was more serious than that in MOH. This difference was considered to reflect the sensitivity of the cortex structure to alcohol damage. In future research, we will focus on the central amygdala (CeA), prefrontal cortex (PFC), orbital-frontal cortex (OFC), hippocampus, and other brain regions for interventions, which may have unexpected benefits for addiction and headache symptoms in MOH patients.

Longitudinal associations between pain and substance use disorder treatment outcomes

INTRODUCTION

Pain is commonly reported among those in treatment for substance use disorders (SUD) and is associated with poorer SUD treatment outcomes. The current study examined the trajectory of pain over the course of SUD treatment and associations with substance use outcomes.

METHODS

This observational study included adults seeking treatment for alcohol, cannabis, or opioid use disorders (N = 811). Participants completed a battery of assessments at treatment admission, 30 days post admission, and at discharge, including measures of demographics, pain, quality of life, abstinence self-efficacy, and craving.

RESULTS

Analyses indicated linear reductions in pain intensity and interference over time. Significant interactive effects were observed for opioid use disorder (OUD) and time, such that participants with OUD had greater reductions in pain intensity and interference over time compared to those without OUD. Elevated pain intensity was associated with negative treatment outcomes, including reduced quality of life and abstinence self-efficacy, and greater craving and negative affect.

CONCLUSIONS

Reductions in pain occur over the course of SUD treatment, particularly for those with OUD. Greater pain was also associated with adverse SUD treatment outcomes. Results suggest that treatment and associated abstinence may be beneficial for those with co-occurring pain and SUD, highlighting an additional benefit of improving access to SUD treatment for patients and health care systems. Future research should replicate these findings among diverse samples and further characterize the trajectory of pain during and after SUD treatment.

Post-Combat-Injury Opioid Prescription and Alcohol Use Disorder in the Military

INTRODUCTION

Previous studies have identified combat exposure and combat traumatic experience as problematic drinking risk factors. Increasing evidence suggests that opioid use increases the risk of alcohol use disorder. This study investigated the association between opioid prescription use after injury and (1) alcohol use disorder and (2) severity of alcohol use disorder among deployed military servicemembers.

METHODS

Deidentified health records data of 9,029 deployed servicemembers from a retrospective cohort study were analyzed. Data were randomly selected from the Department of Defense Trauma Registry and included servicemembers with combat injuries during deployment in Iraq or Afghanistan (2002-2016). Pharmacy records and International Classification of Diseases, Ninth and Tenth Revision diagnosis codes were used. Three groups were identified (no opioid prescription use, nonpersistent opioid prescription use, and persistent opioid prescription use) and were compared on the basis of alcohol use disorder risk using Cox proportional hazard models. Data analyses were performed in 2021.

RESULTS

Of the 9,029 servicemembers with combat injury, 2,262 developed alcohol use disorder (1,322 developed severe alcohol use disorder). Compared with no opioid prescription use, increased alcohol use disorder risk was associated with persistent opioid prescription use, with a hazard ratio of 1.13 (95% CI=1.02, 1.26). After covariate adjustment, increased risk remained statistically significant (hazards ratio=1.24; 95% CI=1.10, 1.39). There was no significant difference in alcohol use disorder risk between no opioid prescription use and nonpersistent opioid prescription use. The risk of severe alcohol use disorder did not vary by opioid use among servicemembers with alcohol use disorder diagnosis.

CONCLUSIONS

The findings of the study suggest that the incidence of alcohol use disorder was higher among injured servicemembers with persistent opioid prescription use than among those without opioid use. If replicated in prospective studies, the findings highlight the need for clinicians to consider the current and history of alcohol use of patients in initiating treatment involving opioids.

Pain trends and pain growth disparities, 2009-2021

Physical pain is a major public health concern. Yet evidence on trends in physical pain around the world barely exists. Using nationally representative data from 146 countries (N = 1.6 million respondents), this paper finds that, all over the world, the percentage of people in pain increased from 26.3 in 2009 to 32.1 in 2021. This rising trend was present in both higher- and lower-income countries. This article also documents pain disparities: In the worldwide population, pain grew faster among women, the less educated, and the poor. Although the aggregate level of pain was greater among the elderly (> 60 years old), the growth in pain was faster among the younger (< 35 years old). These findings hold after controlling for sociodemographic factors. Disparities of pain growth in higher- and lower-income nations and potential explanatory factors are also discussed. Understanding how the level of pain varies over time and across demographic groups is crucial to evaluate and shape public health policies.

Analgesic effects of alcohol in adults with chronic jaw pain

BACKGROUND

Although recent literature provides promising support for the analgesic properties of alcohol, potential differences in alcohol analgesia as a function of chronic pain status are not well understood. Thus, this study examined chronic pain status as a potential moderator of alcohol analgesia and distinguished between multiple aspects of pain experience and sensitivity: pain threshold, pain intensity, pain unpleasantness, and perceived relief.

METHODS

Social drinkers with (N = 19) and without (N = 29) chronic jaw pain completed two testing sessions in a counterbalanced order: alcohol (target BrAC = 0.08 g/dl) and placebo. In each, pressure algometry was performed at the insertion of the masseter. Alcohol analgesia was assessed by examining the main and interactive effects of beverage condition, pressure level (4, 5, or 6 pound-feet [lbf]), and chronic jaw pain status (chronic pain vs. pain-free control) on quantitative sensory testing measures and pain relief ratings following noxious stimuli.

RESULTS

Analyses indicated significant increases in pain threshold and pain relief and reductions in pain unpleasantness and pain intensity, under the alcohol condition. Chronic pain participants demonstrated lower pain thresholds and greater pain intensity and pain unpleasantness ratings than controls. There were no interactive effects of alcohol and pain conditions on any pain measure.

CONCLUSIONS

Findings provide experimental evidence of alcohol's analgesic and pain-relieving effects and suggest that these effects do not significantly differ by chronic pain status. Individuals, who self-medicate pain via alcohol consumption, irrespective of pain status, may be at increased risk to engage in hazardous drinking patterns and thus experience adverse alcohol-related consequences.

Alcohol, Tobacco and Psychotropic Drugs Use Among a Population with Chronic Pain in Southern Spain. A Cross-Sectional Study

BACKGROUND

Substance use seems to be higher among populations with chronic pain.

AIM

The aim of this study is to examine the relationship between the quantity of alcohol, tobacco, and psychotropic drugs consumed and chronic pain among women and men.

METHOD

Linear and logistic regression analyses were carried out using data from the 2015-2016 adults' version of the Andalusian Health Survey which is a representative cross-sectional population-based study (n = 6,569 adults aged >16 years; 50.8% women; 49.2% men).

RESULTS

Disabling chronic pain was statistically associated with higher tobacco consumption among men (β = -30.0, 95% confidenct interval [CI] -59.5 to -0.60; t = -2.0; p < .05). Regarding alcohol, non-disabling chronic pain and a higher quantity of alcohol consumed are statistically associated for both sexes (women: β = 30.4, 95% CI 2.3-58.6; t = 2.12; p < .05 vs. men: β = 164.2, 95% CI 24.3-340.1); t = 2.30; p < .05). For women and men, both disabling chronic pain (women: odds ratio [OR] = 8.7, 95% CI 6.0-12.7); p < .05 vs. men: OR = 3.5, 95% CI 1.5-8.2); p < .05) and non-disabling chronic pain (women: OR = 3.7, 95% CI 2.0-7.0); p <.05 vs. men: OR = 4.7, 95% CI 95% CI 1.5-14.9); p < .05) were statistically significantly associated with a higher consumption of psychotropic drugs.

CONCLUSIONS

Chronic pain may be related to the quantity of alcohol, tobacco, and psychotropic drugs consumed, and disability appears to be one of the factors that modulates this relationship.

Model-Based Analysis of the Influence of Alcohol Use and Age on Pharmacokinetics-Pharmacodynamics of Oral Oxycodone in Middle-Age and Older Community Dwelling Adults

Little is known on how opioid responses vary by age and in the presence of alcohol consumption. This model-based pharmacokinetic-pharmacodynamic (PK-PD) analysis quantified the impact of age and alcohol use on pupillometry and cold pressor test (CPT) PD based on data from an open label study of immediate-release 10 mg oral oxycodone in middle-age and older adults (age 35-85) without severe functional limitations. PK and pupillometry assessments were obtained on 11 occasions over 8 hours. CPT was administered at 1.5, 5 and 8 hours post oxycodone dosing. The study consisted of 62 older adults (age 60+) and 66 middle-age adults (age 35-59), with 82% meeting the unhealthy drinking criteria. Oral oxycodone PK were well described using a one compartment model with a sequential zero to first order absorption process. Recent alcohol use measures were selected a priori. for the analysis. Inhibitory Emax and linear direct effect PD models described the respective pupillometry and CPT data using simultaneous PK-PD analysis in MONOLIX. This analysis demonstrated an influence of age on clearance and bodyweight on the distribution volume of oxycodone, alcohol consumption was not noted to alter oxycodone PK. Oxycodone pupillometry PD were influenced by the level of subject-reported alcohol consumption (AUDIT-C), alcohol use biomarker blood phosphatidylethanol, previous cannabis use, and age. Over the opioid exposure range of the study, none of the covariables including alcohol and age were noted to affect CPT PD. Additional clinical studies are needed to further probe the clinical consequences of opioid-alcohol-age interaction. This article is protected by copyright. All rights reserved.

Brain Imaging Biomarkers for Chronic Pain

The prevalence of chronic pain has reached epidemic levels. In addition to personal suffering chronic pain is associated with psychiatric and medical co-morbidities, notably substance misuse, and a huge a societal cost amounting to hundreds of billions of dollars annually in medical cost, lost wages, and productivity. Chronic pain does not have a cure or quantitative diagnostic or prognostic tools. In this manuscript we provide evidence that this situation is about to change. We first start by summarizing our current understanding of the role of the brain in the pathogenesis of chronic pain. We particularly focus on the concept of learning in the emergence of chronic pain, and the implication of the limbic brain circuitry and dopaminergic signaling, which underly emotional learning and decision making, in this process. Next, we summarize data from our labs and from other groups on the latest brain imaging findings in different chronic pain conditions focusing on results with significant potential for translation into clinical applications. The gaps in the study of chronic pain and brain imaging are highlighted in throughout the overview. Finally, we conclude by discussing the costs and benefits of using brain biomarkers of chronic pain and compare to other potential markers.

Pathophysiological Consequences of At-Risk Alcohol Use; Implications for Comorbidity Risk in Persons Living With Human Immunodeficiency Virus

At-risk alcohol use is a significant risk factor associated with multisystemic pathophysiological effects leading to multiorgan injury and contributing to 5.3% of all deaths worldwide. The alcohol-mediated cellular and molecular alterations are particularly salient in vulnerable populations, such as people living with HIV (PLWH), diminishing their physiological reserve, and accelerating the aging process. This review presents salient alcohol-associated mechanisms involved in exacerbation of cardiometabolic and neuropathological comorbidities and their implications in the context of HIV disease. The review integrates consideration of environmental factors, such as consumption of a Western diet and its interactions with alcohol-induced metabolic and neurocognitive dyshomeostasis. Major alcohol-mediated mechanisms that contribute to cardiometabolic comorbidity include impaired substrate utilization and storage, endothelial dysfunction, dysregulation of the renin-angiotensin-aldosterone system, and hypertension. Neuroinflammation and loss of neurotrophic support in vulnerable brain regions significantly contribute to alcohol-associated development of neurological deficits and alcohol use disorder risk. Collectively, evidence suggests that at-risk alcohol use exacerbates cardiometabolic and neurocognitive pathologies and accelerates biological aging leading to the development of geriatric comorbidities manifested as frailty in PLWH.

Kappa opioid receptor blockade in the nucleus accumbens shell prevents sex-dependent alcohol deprivation effect induced by inflammatory pain

ABSTRACT

Pain-induced negative affect reduces life quality of patients by increasing psychiatric comorbidities, including alcohol use disorders (AUDs). Indeed, clinical data suggest pain as a risk factor to suffer AUDs, predicting relapse drinking in abstinent patients. Here, we analyse the impact of pain on alcohol relapse and the role of kappa opioid receptor (KOR) activation in mediating these pain-induced effects because KORs play an important role in pain-driven negative affect and AUD. Female and male Sprague-Dawley rats underwent 2 alcohol intermittent access periods separated by a forced abstinence period. The complete Freund adjuvant model of inflammatory pain was introduced during abstinence, and alcohol intake before and after alcohol reintroduction was assessed. In addition, we used behavioural approaches to measure stress and memory impairment and biochemical assays to measure KOR expression in abstinence and reintroduction periods. Only female CFA-treated rats increased alcohol intake during the reintroduction period. Concomitantly, this group showed enhanced anxiety-like behaviour and increased KOR expression in the nucleus accumbens shell that was developed during abstinence and remained during the reintroduction period. Finally, KOR antagonist norbinaltorphimine was administered in the nucleus accumbens shell during abstinence to prevent a pain-induced alcohol deprivation effect, a phenomenon observed in CFA-female rats. The administration of norbinaltorphimine effectively blocked a pain-induced alcohol deprivation effect in female rats. Our data evidenced that inflammatory pain constitutes a risk factor to increase alcohol consumption during a reintroduction phase only in female rats by the rise and maintenance of stress probably mediated by KOR signalling in the nucleus accumbens.

Examining Sex Differences in Associations between Pain and Alcohol Use among College Student-Athletes

Background: College student-athletes are a high-risk population for both pain and alcohol use. Although a growing literature indicates that pain motivates alcohol consumption, no studies have tested associations between pain and alcohol in college student-athletes. Methods and Results: Among National Collegiate Athletic Association Division I student-athletes at a large public university (N = 65; 48% Female), nearly all student-athletes (97%) reported alcohol use and 65% reported pain due to an athletic injury. Pain intensity was positively associated with greater motivation to reduce drinking prior to receiving a brief alcohol intervention. Among females, pain intensity was associated with lower self-reported alcohol consumption. Among male athletes, pain-related interference was associated with greater alcohol-related problems and lower perceived ability to deal with alcohol-related situations. Conclusion: Results provide initial evidence that pain may be important to consider when addressing alcohol use among student-athletes.

Patients with alcohol use disorder increase pain and analgesics use: A nationwide population-based cohort study

BACKGROUND

Alcohol has dual effects on many systems, including the pain system. We will test whether and how chronic alcohol consumption enhances pain sensation to develop pain disorder.

METHODS

We conducted a retrospective matched cohort study using data from the National Health Insurance Research Database (NHIRD) in Taiwan, in patients with and without alcohol use disorder (AUD). This study enrolled 19,174 individuals with AUD as study cohort and 19,174 propensity score-matched individuals without AUD as comparison cohort. The outcome was the incidence of pain disorders and the need for analgesics. The hazard ratios of pain disorders and the need for analgesics were evaluated using Cox proportional hazard regression analysis after adjusting for age, sex, index year, comorbidities, urbanization, areas of residence, and insurance premium.

RESULTS

The 14 years of follow-up showed that AUD patients had a higher adjusted hazard ratio (aHR) for developing pain disorders than in non-AUD controls [aHR= 1.290, 95% confidence interval (CI): 1.045-1.591]. Besides, AUD patients had a higher risk of analgesic use (aHR = 1.081, 95% CI: 1.064-1.312), including opioids and non-opioid analgesics. Most importantly, AUD patients required more days of analgesic use, increased dose of analgesics, and higher costs of analgesics. Moreover, AUD patients had more anemia (aHR=2.772, 95% CI: 2.581-2.872), which could be a mediating factor.

CONCLUSIONS

AUD patients had higher risks of developing pain disorders and subsequently increased analgesic demand. These results suggest that AUD worsened pain, and pain syndrome is correlated with the duration of chronic alcohol exposure.

Elevated customary alcohol consumption attenuates opioid effects

BACKGROUND

Regular alcohol consumption is on the rise among older adults and has the potential of altering the subjective experience of pain and response to pain medications. This study examined the cognitive, analgesic and side effect response to oxycodone in middle age and older adults with elevated levels of customary alcohol consumption in a human laboratory setting.

METHODS

After refraining from alcohol for one day, eligible participants underwent baseline assessment cognition and side effects by means of questionnaires that were repeated at three time points (90 min, 5 and 8 h) following administration of a 10 mg oral dose of oxycodone. Response to pain stimulus (Cold Pressor Test (CPT)), pupil size, and plasma oxycodone were also measured.

RESULTS

One hundred twenty-eight adults (age 35-85) completed the study day. Compared to those with lower customary alcohol consumption, participants with elevated alcohol consumption showed attenuated opioid-induced pupil constriction and cognitive decline on objective measures of working memory, sustained attention, inhibitory control, coordination on a simulated driving task, and subjective dysphoric effects with enhanced subjective euphoric effects. Oxycodone pharmacokinetics, pain tolerance to CPT, and Berg balance were impacted comparably between alcohol consumption groups. Women endorsed greater negative drug effects, whereas men endorsed positive drug effects.

CONCLUSION

Independent of subject's age, elevated customary alcohol consumption attenuates opioid central effects (i.e., pupil miosis, impaired cognition) and gender influences subjective drug effects. Clinicians should consider alcohol consumption and gender when prescribing opioid medications.

Alcohol amplifies cingulate cortex signaling and facilitates immobilization-induced hyperalgesia in female rats

Complex Regional Pain Syndrome (CRPS) is a musculoskeletal pain condition that often develops after limb injury and/or immobilization. Although the exact mechanisms underlying CRPS are unknown, the syndrome is associated with central and autonomic nervous system dysregulation and peripheral hyperalgesia symptoms. These symptoms also manifest in alcoholic neuropathy, suggesting that the two conditions may be pathophysiologically accretive. Interestingly, people assigned female at birth (AFAB) appear to be more sensitive to both CRPS and alcoholic neuropathy. To better understand the biobehavioral mechanisms underlying these conditions, we investigated a model of combined CRPS and alcoholic neuropathy in female rats. Animals were pair-fed either a Lieber-DeCarli alcohol liquid diet or a control diet for ten weeks. CRPS was modeled via unilateral hind limb cast immobilization for seven days, allowing for the other limb to serve as a within-subject control for hyperalgesia measures. To investigate the role of circulating ovarian hormones on pain-related behaviors, half of the animals underwent ovariectomy (OVX). Using the von Frey procedure to record mechanical paw withdrawal thresholds, we found that cast immobilization and chronic alcohol drinking separately and additively produced mechanical hyperalgesia observed 3 days after cast removal. We then examined neuroadaptations in AMPA GluR1 and NMDA NR1 glutamate channel subunits, extracellular signal-regulated kinase (ERK), and cAMP response element-binding protein (CREB) in bilateral motor and cingulate cortex across all groups. Consistent with increased pain-related behavior, chronic alcohol drinking increased GluR1, NR1, ERK, and CREB phosphorylation in the cingulate cortex. OVX did not alter any of the observed effects. Our results suggest accretive relationships between CRPS and alcoholic neuropathy symptoms and point to novel therapeutic targets for these conditions.

Cognitive-Affective Transdiagnostic Factors Associated With Vulnerability to Alcohol and Prescription Opioid Use in the Context of Pain

The use of alcohol and prescription opioids is common among people in pain and poses significant public health burdens. This review identifies factors associated with motivation to use alcohol and prescription opioids in the context of pain. Pain-relevant, cognitive-affective, transdiagnostic vulnerability factors-expectancies/motives, pain catastrophizing, pain-related anxiety, distress intolerance, anxiety sensitivity, and perceived interrelations-were selected from theoretical conceptualizations of pain and substance use. Searches conducted in PubMed, PsycINFO, and Embase returned 25 studies that examined associations between identified variables of interest and the use of alcohol and prescription opioids in the context of pain. Consistent with a larger literature on pain and substance use, the studies included in this review demonstrated that people with chronic pain are motivated to use alcohol and opioids in response to negative affect and hold expectancies/motives for coping with pain. Vulnerabilities that engender difficulty managing aversive internal states (distress intolerance and anxiety sensitivity) and maladaptive responses to pain (pain-related anxiety and pain catastrophizing) also were implicated in motivation for alcohol and opioid use. Although one study found that pain-related anxiety was associated with co-use of alcohol and opioids, no studies examined simultaneous use. Future research directions that can explicate causal associations, identify patterns of alcohol and opioid co-use, clarify the role of pain in cessation processes, and inform treatment development are discussed.

Antagonism of Sigma-1 receptor blocks heavy alcohol drinking and associated hyperalgesia in male mice

BACKGROUND

Alcohol use disorder (AUD) is a complex psychiatric disease characterized by high alcohol intake as well as hyperkatifeia and hyperalgesia during withdrawal. A role for Sigma-1 receptors (Sig-1Rs) in the rewarding and reinforcing effects of alcohol has started to emerge in recent years, as rat studies have indicated that Sig-1R hyperactivity may result in excessive alcohol drinking. Sig-1R studies in mice are very scarce, and its potential role in alcohol-induced hyperalgesia is also unknown.

METHODS

In this study, we investigated the role of Sig-1R in alcohol drinking and associated hyperalgesia in male mice, using an intermittent access 2-bottle choice model of heavy drinking.

RESULTS

The Sig-1R antagonist BD-1063 was found dose dependently to reduce both alcohol intake and preference, without affecting either water or sucrose intake, suggesting that the effects are specific for alcohol. Notably, the ability of BD-1063 to suppress ethanol intake correlated with the individual baseline levels of alcohol drinking, suggesting that the treatment was more efficacious in heavy drinking animals. In addition, BD-1063 reversed alcohol-induced hyperalgesia during withdrawal, assessed using an automatic Hargreaves test, without affecting thermal sensitivity in alcohol-naïve animals or locomotor activity in either group.

CONCLUSIONS

These data show that Sig-1R antagonism dose-dependently reduced ethanol consumption in heavy drinking mice as well as its efficacy in reducing alcohol-induced hyperalgesia. These findings provide a foundation for the development of novel treatments for AUD and associated pain states.

The Association of Smoking and Alcohol Abuse on Anxiety and Depression in Patients With Recurrent Acute or Chronic Pancreatitis Undergoing Total Pancreatectomy and Islet Autotransplantation: A Report From the Prospective Observational Study of TPIAT Cohort

OBJECTIVES

Smoking and alcohol use are risk factors for acute and chronic pancreatitis, and their role on anxiety, depression, and opioid use in patients who undergo total pancreatectomy and islet autotransplantation (TPIAT) is unknown.

METHODS

We included adults enrolled in the Prospective Observational Study of TPIAT (POST). Measured variables included smoking (never, former, current) and alcohol abuse or dependency history (yes vs no). Using univariable and multivariable analyses, we investigated the association of smoking and alcohol dependency history with anxiety and depression, opioid use, and postsurgical outcomes.

RESULTS

Of 195 adults studied, 25 were current smokers and 77 former smokers, whereas 18 had a history of alcohol dependency (of whom 10 were current smokers). A diagnosis of anxiety was associated with current smoking (P = 0.005), and depression was associated with history of alcohol abuse/dependency (P = 0.0001). However, active symptoms of anxiety and depression at the time of TPIAT were not associated with smoking or alcohol status. Opioid use in the past 14 days was associated with being a former smoker (P = 0.005).

CONCLUSIONS

Active smoking and alcohol abuse history were associated with a diagnosis of anxiety and depression, respectively; however, at the time of TPIAT, symptom scores suggested that they were being addressed.

Anxiety sensitivity, pain severity and co-use of cigarettes and e-cigarettes among adults with chronic pain

Anxiety sensitivity (fear of potential negative consequences of anxiety-related symptoms/sensations) has been identified as a transdiagnostic factor in comorbid pain and nicotine dependence and evidence suggests that anxiety sensitivity may be indirectly associated with nicotine use via greater pain severity. Therefore, this study tested the hypothesis that anxiety sensitivity is associated with cigarette and e-cigarette use/co-use directly and indirectly via greater pain severity. Participants included 273 online survey respondents with chronic musculoskeletal pain (34% female; Mage = 32.9). Anxiety sensitivity was positively associated with cigarette smoking, e-cigarette use and cigarette/e-cigarette co-use (ps < .05). Furthermore, anxiety sensitivity was indirectly and positively associated with cigarette smoking, e-cigarette use and co-use via greater chronic pain severity. Pain severity may play an important role in associations between anxiety sensitivity and nicotine dependence and prospective research should examine temporal/causal effects of anxiety sensitivity in relation to pain severity and nicotine/tobacco use.

A measure of expectancies for alcohol analgesia: Preliminary factor analysis, reliability, and validity

Rates of alcohol consumption are substantially higher among persons with pain, and recent research has focused on elucidating bidirectional pain-alcohol effects. Expectancies for alcohol analgesia could influence the degree to which alcohol confers acute pain-relieving effects, and may amplify the propensity to respond to pain with drinking behavior. However, no validated measures of expectancies for alcohol analgesia are available. Therefore, we developed a five-item measure of Expectancies for Alcohol Analgesia (EAA), which assesses the perceived likelihood that alcohol will reduce pain. The goal of this project was to examine psychometric properties of the EAA among a sample of 273 current alcohol users with chronic pain (M_age = 32.9; 34% female) who completed an online survey of pain and substance use. Confirmatory factor analysis (CFA) results indicated that the hypothesized single-factor structure of the EAA provided good model fit (Bollen-Stine bootstrap p = .13). The EAA also showed excellent internal consistency (α = 0.97), and scores were positively associated with quantity/frequency of alcohol use, alcohol outcome expectancies, coping-related drinking motives, and pain severity (ps < 0.01). These findings provide initial support regarding the single-factor structure, reliability, and validity of the EAA. Examination of predictive utility and further validation are important next steps.

Spinal astrocyte aldehyde dehydrogenase-2 mediates ethanol metabolism and analgesia in mice

BACKGROUND

Little is known about the targets in the CNS that mediate ethanol analgesia. This study explores the role of spinal astrocyte aldehyde dehydrogenase-2 (ALDH2), a key ethanol-metabolising enzyme, in the analgesic effects of ethanol in mice.

METHODS

Astrocyte and hepatocyte ALHD2-deficient mice were generated and tested in acute and chronic pain models. Cell-type-specific distribution of ALDH2 was analysed by RNA in situ hybridisation in spinal slices from astrocytic ALDH2-deficient mice and their wild-type littermates. Spinal ethanol metabolites and γ-aminobutyric acid (GABA) content were measured using gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry.

RESULTS

ALDH2 mRNA was expressed in both astrocytes and neurones in spinal cord slices. Astrocyte ALDH2-deficient mice had decreased expression of ALDH2 mRNA in astrocytes, but not in neurones. Astrocyte ALDH2 deficiency inhibited ethanol-derived acetate, but not acetaldehyde content in spinal cord tissues. Depletion of spinal astrocyte ALDH2 selectively inhibited ethanol-induced anti-nociceptive effect, but not the effect of ethanol, on motor function. Astrocyte ALDH2 deficiency abolished ethanol-induced GABA elevation. The ethanol metabolite acetate produced anti-nociception and increased GABA synthesis in a manner similar to ethanol. I.T. delivery of either GABA_A or GABA_B receptor antagonists prevented ethanol and acetate-induced analgesia.

CONCLUSIONS

These findings provide evidence that ALDH2 in spinal astrocytes mediates spinal ethanol metabolism and ethanol-induced analgesic effects by promoting GABA synthesis and GABAergic transmission in spinal cord.