Laboratory-induced cue reactivity among individuals with prescription opioid dependence

Opioid craving does not incubate over time in inpatient or outpatient treatment studies: Is the preclinical incubation of craving model lost in translation?

Within addiction science, incubation of craving is an operational label used to describe time-dependent increases in drug seeking during periods of drug deprivation. The purpose of this systematic review was to describe the preclinical literature on incubation of craving and the clinical literature on craving measured over extended periods of abstinence to document this translational homology and factors impacting correspondence. Across the 44 preclinical studies that met inclusion criteria, 31 reported evidence of greater lever pressing, nose pokes, spout licks, or time spent in drug-paired compartments (i.e., drug seeking) relative to neutral compartments after longer periods of abstinence relative to shorter periods of abstinence, labelled as "incubation of craving." In contrast, no clinical studies (n = 20) identified an increase in opioid craving during longer abstinence periods. The lack of clinical evidence for increases in craving in clinical populations weakens the translational utility of operationalizing the time-dependent increase in drug-seeking behavior observed in preclinical models as models of incubation of "craving".

Noninvasive Vagal Nerve Stimulation for Opioid Use Disorder

Background

Opioid Use Disorder (OUD) is an escalating public health problem with over 100,000 drug overdose-related deaths last year most of them related to opioid overdose, yet treatment options remain limited. Non-invasive Vagal Nerve Stimulation (nVNS) can be delivered via the ear or the neck and is a non-medication alternative to treatment of opioid withdrawal and OUD with potentially widespread applications.

Methods

This paper reviews the neurobiology of opioid withdrawal and OUD and the emerging literature of nVNS for the application of OUD. Literature databases for Pubmed, Psychinfo, and Medline were queried for these topics for 1982-present.

Results

Opioid withdrawal in the context of OUD is associated with activation of peripheral sympathetic and inflammatory systems as well as alterations in central brain regions including anterior cingulate, basal ganglia, and amygdala. NVNS has the potential to reduce sympathetic and inflammatory activation and counter the effects of opioid withdrawal in initial pilot studies. Preliminary studies show that it is potentially effective at acting through sympathetic pathways to reduce the effects of opioid withdrawal, in addition to reducing pain and distress.

Conclusions

NVNS shows promise as a non-medication approach to OUD, both in terms of its known effect on neurobiology as well as pilot data showing a reduction in withdrawal symptoms as well as physiological manifestations of opioid withdrawal.

Pain is reduced by transcutaneous cervical vagus nerve stimulation and correlated with cardiorespiratory variability measures in the context of opioid withdrawal

Over 100,000 individuals in the United States lost their lives secondary to drug overdose in 2021, with opioid use disorder (OUD) being a leading cause. Pain is an important component of opioid withdrawal, which can complicate recovery from OUD. This study's objectives were to assess the effects of transcutaneous cervical vagus nerve stimulation (tcVNS), a technique shown to reduce sympathetic arousal in other populations, on pain during acute opioid withdrawal and to study pain's relationships with objective cardiorespiratory markers. Twenty patients with OUD underwent opioid withdrawal while participating in a two-hour protocol. The protocol involved opioid cues to induce opioid craving and neutral conditions for control purposes. Adhering to a double-blind design, patients were randomly assigned to receive active tcVNS (n = 9) or sham stimulation (n = 11) throughout the protocol. At the beginning and end of the protocol, patients' pain levels were assessed using the numerical rating scale (0–10 scale) for pain (NRS Pain). During the protocol, electrocardiogram and respiratory effort signals were measured, from which heart rate variability (HRV) and respiration pattern variability (RPV) were extracted. Pre- to post- changes (denoted with a Δ) were computed for all measures. Δ NRS Pain scores were lower (P = 0.045) for the active group (mean ± standard deviation: −0.8 ± 2.4) compared to the sham group (0.9 ± 1.0). A positive correlation existed between Δ NRS pain scores and Δ RPV (Spearman's ρ = 0.46; P = 0.04). Following adjustment for device group, a negative correlation existed between Δ HRV and Δ NRS Pain (Spearman's ρ = −0.43; P = 0.04). This randomized, double-blind, sham-controlled pilot study provides the first evidence of tcVNS-induced reductions in pain in patients with OUD experiencing opioid withdrawal. This study also provides the first quantitative evidence of an association between breathing irregularity and pain. The correlations between changes in pain and changes in objective physiological markers add validity to the data. Given the clinical importance of reducing pain non-pharmacologically, the findings support the need for further investigation of tcVNS and wearable cardiorespiratory sensing for pain monitoring and management in patients with OUD.

Learning from addiction: Craving of prescription opioids in chronic pain sufferers

Prescription opioids are a primary driver of opioid-related deaths. Although craving is a substantial component of OUD, the degree to which craving leads to misuse among chronic pain patients on long-term prescription opioids is unknown. A clear understanding of the factors that lead to misuse in this vulnerable population is needed for the development of safe and effective practices for opioid taper. This narrative review summarizes the relevant literature on the role of craving in addiction and chronic pain through epidemiological and behavioral studies. The first part of this review examines the role of craving in predicting opioid use/misuse in individuals with chronic pain with and without OUD. The second part covers methods on how craving is evaluated experimentally using both subjective and objective measures and provides related findings. The overall goal of this review is to facilitate the development of a population-specific description of craving in those who use opioids to control chronic pain and to describe how it may be mechanistically linked to patterns of opioid (mis)use.

Does Effectiveness of a Brief Substance Use Treatment Depend on PTSD? An Evaluation of Motivational Enhancement Therapy for Active-Duty Army Personnel

OBJECTIVE

Posttraumatic stress disorder (PTSD) with comorbid substance use disorders (SUDs) has been associated with poorer treatment outcomes. The present study examined associations between provisional PTSD at baseline and 3 months with 6-month treatment outcomes from either a one-session motivational enhancement therapy (MET) or education intervention addressing substance use.

METHOD

Secondary analyses were conducted on a randomized clinical trial comparing a novel MET intervention to an educational intervention for Army personnel with SUD who were not engaged in SUD treatment (n = 242; 92.1% male). We compared three groups with complete data on baseline and 3-month provisional PTSD: individuals without provisional PTSD at baseline (n = 98), those with provisional PTSD remitted by 3 months (n = 42), and those with provisional PTSD unremitted at 3 months (n = 53) on alcohol use frequency, quantity, consequences, and related diagnoses.

RESULTS

Individuals with unremitted provisional PTSD were at increased risk for moderate/severe alcohol use disorder at 6 months relative to those without baseline provisional PTSD (odds ratio = 4.53, p = .007). The effect of MET on drinks per week at 6 months (controlling for baseline) differed with a significant effect of MET for individuals with remitted provisional PTSD (count ratio = 0.41, p = .005).

CONCLUSIONS

Both interventions were effective in reducing drinking even for those with provisional PTSD, although, compared with education, MET had slightly better effects on reducing drinking quantity for those with remitted PTSD. Findings suggest that PTSD remission may serve as an early prognostic indicator of long-term alcohol use changes, or alternatively, delivery of MET during heightened transitory distress may be most effective for reducing alcohol use.

Transcutaneous Cervical Vagus Nerve Stimulation Reduces Respiratory Variability in the Context of Opioid Withdrawal

Opioid withdrawal's physiological effects are a major impediment to recovery from opioid use disorder (OUD). Prior work has demonstrated that transcutaneous cervical vagus nerve stimulation (tcVNS) can counteract some of opioid withdrawal's physiological effects by reducing heart rate and perceived symptoms. The purpose of this study was to assess the effects of tcVNS on respiratory manifestations of opioid withdrawal - specifically, respiratory timings and their variability. Patients with OUD (N = 21) underwent acute opioid withdrawal over the course of a two-hour protocol. The protocol involved opioid cues to induce opioid craving and neutral conditions for control purposes. Patients were randomly assigned to receive double-blind active tcVNS (n = 10) or sham stimulation (n = 11) throughout the protocol. Respiratory effort and electrocardiogram-derived respiration signals were used to estimate inspiration time (T_i), expiration time (T_e), and respiration rate (RR), along with each measure's variability quantified via interquartile range (IQR). Comparing the active and sham groups, active tcVNS significantly reduced IQR(T_i) - a variability measure - compared to sham stimulation (p = .02). Relative to baseline, the active group's median change in IQR(T_i) was 500 ms less than the sham group's median change in IQR(T_i). Notably, IQR(T_i) was found to be positively associated with post-traumatic stress disorder symptoms in prior work. Therefore, a reduction in IQR(T_i) suggests that tcVNS downregulates the respiratory stress response associated with opioid withdrawal. Although further investigations are necessary, these results promisingly suggest that tcVNS - a non-pharmacologic, non-invasive, readily implemented neuromodulation approach - can serve as a novel therapy to mitigate opioid withdrawal symptoms.

Sex and drug differences in stress, craving and cortisol response to the trier social stress task

RATIONALE

The hypothalamic-pituitary-adrenal (HPA) axis is a critical hormonal system involved in stress response. A number of studies have investigated the HPA axis response of drug-dependent individuals to stressors. Stress-induced vulnerabilities in the HPA axis may differ in response to chronic use of different substances, possibly leading to different target therapies. There has not been a direct comparison of HPA axis and subjective response between individuals with different types of substance use disorders following a laboratory stress intervention.

OBJECTIVES

The primary goal of the current study was to compare subjective and neuroendocrine response to the Trier Social Stress Task (TSST) across multiple primary types of substance use disorders and investigate differential response between males and females.

METHODS

Four hundred participants were drawn from seven studies completed at the Medical University of South Carolina between 2011 and 2021. The TSST was utilized across studies and subjective and neuroendocrine responses measured following completion. Generalized linear mixed effects models and area under the response curve analysis were used to compare both substance type and sex differences.

RESULTS

The study groups involving individuals with cocaine use disorder had blunted stress, craving and cortisol response following the TSST as compared to other substance use groups. Females in the cocaine groups reported higher subjective stress but lower cortisol than males.

CONCLUSIONS

The study results indicate that there may be differential effects of substances on the HPA axis, with cocaine using individuals exhibiting more blunting of the HPA axis response as compared to users of other substances.

Transcutaneous cervical vagus nerve stimulation reduces behavioral and physiological manifestations of withdrawal in patients with opioid use disorder: A double-blind, randomized, sham-controlled pilot study

BACKGROUND

Opioid Use Disorder (OUD) is a serious public health problem, and the behavioral and physiological effects of opioid withdrawal can be a major impediment to recovery. Medication for OUD is currently the mainstay of treatment; however, it has limitations and alternative approaches are needed.

OBJECTIVE

The purpose of this study was to assess the effects of transcutaneous cervical vagus nerve stimulation (tcVNS) on behavioral and physiological manifestations of acute opioid withdrawal.

METHODS

Patients with OUD undergoing acute opioid withdrawal were randomly assigned to receive double blind active tcVNS (N = 10) or sham stimulation (N = 11) while watching neutral and opioid cue videos. Subjective opioid withdrawal, opioid craving, and anxiety were measured using a Visual Analogue Scale (VAS). Distress was measured using the Subjective Units of Distress Scale (SUDS), and pain was measured using the Numerical Rating Scale (NRS) for pain. Electrocardiogram signals were measured to compute heart rate. The primary outcomes of this initial phase of the clinical trial (ClinicalTrials.gov NCT04556552) were heart rate and craving.

RESULTS

tcVNS compared to sham resulted in statistically significant reductions in subjective opioid withdrawal (p = .047), pain (p = .045), and distress (p = .004). In addition, tcVNS was associated with lower heart rate compared to sham (p = .026). Craving did not significantly differ between groups (p = .11).

CONCLUSIONS

tcVNS reduces behavioral and physiological manifestations of opioid withdrawal, and should be evaluated in future studies as a possible non-pharmacologic, easily implemented approach for adjunctive OUD treatment.

A pilot study of benzodiazepine cue-induced craving

OBJECTIVES

The misuse of benzodiazepines is a growing concern due to increases in both access to these medications and their associated public health harms, most concerningly risk for overdose when combined with other substances. Although cue reactivity-the subjective and physiological response to cues or reminders of substance use-has been identified for most major classes of substances, it has yet to be studied with benzodiazepines. In this preliminary study, our objective was to assess whether images of benzodiazepines were associated with greater craving and anxiety than neutral images in adults who reported misuse of benzodiazepines.

METHODS

We recruited a sample of 38 adults from a substance use disorder treatment setting and administered a standard cue reactivity task using pictorial images along with a battery of self-report measures.

RESULTS

Results indicated significantly higher craving and anxiety in response to benzodiazepine relative to neutral cues, with cues eliciting a moderate to high level of craving, on average. Craving was associated with several risk factors for benzodiazepine misuse, including insomnia and distress intolerance.

CONCLUSIONS

This preliminary study suggests that benzodiazepine cues can become conditioned to elicit craving responses and that the degree of cue reactivity is correlated with known risk factors for benzodiazepine misuse.

Effects of arousal modulation via resonance breathing on craving and affect in women with substance use disorder

BACKGROUND

Craving for alcohol and other drugs is a complex in-the-moment experience that involves within-person changes in physiological arousal and affect. We evaluated the utility of a just-in-time, self-administered resonance breathing smartphone application (app) to reduce craving and improve affect in women during outpatient treatment for substance use disorders (SUD).

METHODS

Women (N = 57) receiving outpatient addiction treatment were randomized to practice either cardiovascular resonance breathing (0.1 Hz/6 breaths per minute) or a sham (∼0.23 Hz/14 breaths per minute) in the face of urges over an 8-week intervention. Craving (Penn Alcohol Craving Scale) and affect (Positive and Negative Affect Scale) were collected weekly throughout the intervention. App data were uploaded weekly to assess frequency of use. Generalized Estimated Equations modeled craving and affect as a function of group randomization and app use frequency across the 8-week intervention.

FINDINGS

Higher levels of craving were associated with more frequent app use. The group X app use interaction was significant for craving. Frequent app use during the intervention phase was associated with lower craving levels in the resonance breathing group relative to the sham group over the 8-week intervention. There was no effect of app use frequency on affect measures.

CONCLUSIONS

Women assigned to practice sham breathing who used the intervention frequently experienced elevations in craving that are commonly reported during outpatient SUD treatment. Women assigned to resonance breathing who used the intervention frequently did not experience such increases. Resonance breathing may be protective against triggers in outpatient treatment. Physiological mechanisms are discussed.

Nonjudgmental acceptance: Associations with substance-related cue reactivity in adults with substance use disorders and posttraumatic stress

The present investigation examined the predictive utility of nonjudgmental acceptance, a facet of mindfulness defined as the ability to remain aware and nonevaluative about internal experience, in terms of substance-related cue reactivity among adults with substance use disorders (SUD) and posttraumatic stress (PTS) symptomatology. We hypothesized that higher nonjudgmental acceptance, indexed via self-report, would predict higher levels of self-reported control over oneself and safety 'in the moment', broadly, and lower levels of substance-related craving in response to substance script cues. Effects were expected after subtracting reactivity to neutral script cues from each outcome rating. PTS severity was included as a covariate. The sample was comprised of 53 adults (48.1% women; 75.9% African American; 74.1% with past-month PTSD) with substance dependence per DSM-IV and at least four symptoms of PTSD per DSM-5. Higher baseline nonjudgmental acceptance predicted greater safety and control in response to substance cues; no effects were found for craving. These experimental laboratory results elucidate the potential clinical utility of mindfulness-based interventions in bolstering recovery from addiction among adults with SUD/PTS by fostering safety and control in response to substance cues.

Heightened autonomic reactivity to negative affective stimuli among active duty soldiers with PTSD and opioid-treated chronic pain

Within military populations, chronic pain conditions and posttraumatic stress disorder (PTSD) frequently co-occur, however, little research has examined the psychophysiological correlates of this comorbidity among active-duty soldiers. The current study examined physiological reactivity to negative affective stimuli among 30 active duty soldiers with chronic pain conditions treated with long-term opioid therapy. Participants completed a diagnostic interview and self-report measures. Then, their heart rate and skin temperature were recorded during an affective picture-viewing task. Soldiers with PTSD exhibited greater increases in the ratio of low-to-high frequency heart rate variability (LF/HF HRV) while viewing negative affective images than soldiers without PTSD. PTSD symptom severity was positively associated with LF/HF HRV reactivity and negatively associated with skin temperature reactivity. Additionally, opioid craving was associated with LF/HF HRV and skin temperature reactivity among soldiers with PTSD. Taken together, the results of the present study provide evidence for heightened sympathetic nervous system reactivity among soldiers with comorbid chronic pain and PTSD, underscoring the importance of intervening on potential risk factors for these conditions.

Laboratory-induced stress and craving predict opioid use during follow-up among individuals with prescription opioid use disorder

BACKGROUND

Opioid use disorder (OUD) remains a public health crisis in the USA. Although stress and craving are common precipitants of substance use, no research to date has investigated the impact of laboratory-induced stress and craving on subsequent opioid use.

METHOD

Participants (N = 31) were individuals with prescription OUD who completed a human laboratory study followed by a one-month follow-up visit. Participants were randomly assigned to either a stress task (i.e., Trier Social Tress Task; TSST) or a no-stress condition, and then all participants completed an opioid cue paradigm. Measures of subjective (e.g., stress, craving), and neuroendocrine (e.g., cortisol, dehydroepiandrosterone) reactivity were assessed before and after each task. Survival and regression models tested the association between reactivity to the laboratory tasks and a) time to first opioid use and b) amount of opioid use during follow-up.

RESULTS

On average, participants first used opioids 3.65 (SD = 2.08) days following the study. Craving after the opioid cue paradigm (B = 0.44, Exp(B) = 1.55, 95 % CI [1.06, 2.28], p = .02) and after the TSST/no-stress condition plus opioid cue paradigm (B = 1.06, Exp(B) = 2.88, 95 % CI [1.70, 4.85], p < .001) predicted time to first use. Additionally, there was a significant interaction between randomization to the TSST, stress reactivity, and amount of opioids used.

CONCLUSIONS

Findings demonstrate that elevated cue-induced craving, either in the context of a stressor or not, is associated with shortened time to opioid use, whereas stress reactivity impacts the amount of opioids consumed. Preliminary findings add to the literature on stress, craving and opioid use and implicate treatment.

Realize, Analyze, Engage (RAE): A Digital Tool to Support Recovery from Substance Use Disorder

Background:

Substance use disorders are a highly prevalent group of chronic diseases with devastating individual and public health consequences. Current treatment strategies suffer from high rates of relapse, or return to drug use, and novel solutions are desperately needed. Realize Analyze Engage (RAE) is a digital, mHealth intervention that focusses on real time, objective detection of high-risk events (stress and drug craving) to deploy just-in-time supportive interventions. The present study aims to (1) evaluate the accuracy and usability of the RAE system and (2) evaluate the impact of RAE on patient centered outcomes.

Methods:

The first phase of the study will be an observational trial of N = 50 participants in outpatient treatment for SUD using the RAE system for 30 days. Accuracy of craving and stress detection algorithms will be evaluated, and usability of RAE will be explored via semi-structured interviews with participants and focus groups with SUD treatment clinicians. The second phase of the study will be a randomized controlled trial of RAE vs usual care to evaluate rates of return to use, retention in treatment, and quality of life.

Anticipated findings and future directions:

The RAE platform is a potentially powerful tool to de-escalate stress and craving outside of the clinical milieu, and to connect with a support system needed most. RAE also aims to provide clinicians with actionable insight to understand patients’ level of risk, and contextual clues for their triggers in order to provide more personalized recovery support.

Insights into the Neurobiology of Craving in Opioid Use Disorder

Purpose of review

Opioids remain the most potent form of pain relief currently available, yet have a high abuse liability. Here we discuss underlying neurobiological changes in Opioid Use Disorder (OUD) that likely contribute to drug craving, which in turn drives continued drug use and relapse.

Recent findings

Craving has emerged as a strong indicator in drug-seeking and relapse. Studies have demonstrated a number of allostatic changes in circuitry that facilitate learning of drug-stimuli relationships, thereby augmenting cue-triggered drug use and relapse.

Summary

This review will focus on key neurobiological changes in underlying circuitry observed during the initial and continued exposure to opioids that result in an increase in neural-reactivity to drug-related intrinsic and extrinsic drug cues, and to enhanced learning of drug-context correlations. This sensitized learning state may be an indication of the underlying framework that drives craving and ultimately, motivates increased salience of drug cues and drives drug-seeking.

Salivary measurement and mindfulness-based modulation of prescription opioid cue-reactivity

BACKGROUND

Chronic pain patients on long-term opioid therapy (LTOT) may be at elevated risk for developing conditioned opioid cue-reactivity as their prescribed dosing schedules simultaneously function as fixed reinforcement schedules. Since opioids are typically consumed orally during LTOT, it stands to reason that opioid cue exposure might elicit conditioned salivary responses. However, no study has examined salivary cue-reactivity among opioid users during in-vivo exposure to their own prescription opioid medication.

METHODS

Two samples (N = 68, N = 39) of chronic pain patients on LTOT were recruited from primary care and specialty care clinics. Study 1 aimed to determine whether chronic pain patients receiving LTOT exhibited salivary cue-reactivity to their prescribed opioid. Study 2 was a pilot study that aimed to assess the effects of behavioral treatment on chronic pain patients' salivary cue-reactivity.

RESULTS

In Study 1, exposure to the patient's own prescribed opioid resulted in significantly greater increases in salivation and cue-elicited craving than exposure to a neutral cue. In Study 2 participants who were randomized to an 8-week Mindfulness-Oriented Recovery Enhancement intervention evidenced significantly greater decreases in opioid cue-reactivity than participants in an active control condition as evidenced by both reduced salivation and craving ratings.

CONCLUSIONS

Study findings demonstrate salivation may serve as a useful, objective index of opioid cue-reactivity. With further refinement of this task, conditioned salivary response could be used to identify especially vulnerable patients, who then could be targeted with a personalized medicine approach for selective and intensive prevention/treatment interventions to preempt escalation of opioid use to opioid misuse and OUD.

Wearable sensor-based detection of stress and craving in patients during treatment for substance use disorder: A mixed methods pilot study

AIMS

To determine the accuracy of a wearable sensor to detect and differentiate episodes of self-reported craving and stress in individuals with substance use disorders, and to assess acceptability, barriers, and facilitators to sensor-based monitoring in this population.

METHODS

This was an observational mixed methods pilot study. Adults enrolled in an outpatient treatment program for a substance use disorder wore a non-invasive wrist-mounted sensor for four days and self-reported episodes of stress and craving. Continuous physiologic data (accelerometry, skin conductance, skin temperature, and heart rate) were extracted from the sensors and analyzed via various machine learning algorithms. Semi-structured interviews were conducted upon study completion, and thematic analysis was conducted on qualitative data from semi-structured interviews.

RESULTS

Thirty individuals completed the protocol, and 43 % (N = 13) were female. A total of 41 craving and 104 stress events were analyzed. The differentiation accuracies of the top performing models were as follows: stress vs. non-stress states 74.5 % (AUC 0.82), craving vs. no-craving 75.7 % (AUC 0.82), and craving vs. stress 76.8 % (AUC 0.8). Overall participant perception was positive, and acceptability was high. Emergent themes from the exit interviews included a perception of connectedness and increased mindfulness related to wearing the sensor, both of which were reported as helpful to recovery. Barriers to engagement included interference with other daily wear items, and perceived stigma.

CONCLUSIONS

Wearable sensors can be used to objectively differentiate episodes of craving and stress, and individuals in recovery from substance use disorder are accepting of continuous monitoring with these devices.

Stress and opioid use disorder: A systematic review

Medication assisted treatment (MAT) is highly effective in reducing illicit opioid use and preventing overdose in individuals with opioid use disorder (OUD); however, treatment retention of patients engaged in MAT is a significant clinical concern. The experience of stress may contribute to a decision to drop out of treatment. The current study is a systematic review conducted across multiple databases of empirical studies on primary appraisal of stress and its relationship to opioid craving, opioid use, and OUD treatment outcomes. Primary appraisal of stress is defined as an explicit inquiry into individual perception of feeling stressed using a self-report measure administered in laboratory, clinical, or naturalistic environment. A total of 21 included studies were organized into three categories: observed stress, experimentally-induced stress, and stress-focused interventions. Appraised stress was generally associated with greater craving, but associations with opioid use and treatment retention were mixed. All but one study included MAT samples and every study sample included some form of drug counseling. These findings suggest that individuals experience considerable stress in spite of receiving standard treatment for OUD. Psychopharmacological interventions targeting stress were promising, but no behavioral interventions specific to stress management were found. The preliminary results with clonidine and lofexidine targeting stress in individuals with OUD warrant further studies. To better understand the impact of stress in OUD, future research should consider using repeated assessment of stress in the context of daily life. Utilization of behavioral treatments specifically targeting stress could have benefits in improving OUD outcomes.

Craving in Opioid Use Disorder: From Neurobiology to Clinical Practice

Opioid use disorder (OUD) is a major public health issue that has reached epidemic levels in some parts of the world. It is a chronic and complex neurobiological disease associated with frequent relapse to drug taking. Craving, defined as an overwhelmingly strong desire or need to use a drug, is a central component of OUD and other substance use disorders. In this review, we describe the neurobiological and neuroendocrine pathways that underpin craving in OUD and also focus on the importance of assessing and treating craving in clinical practice. Craving is strongly associated with patients returning to opioid misuse and is therefore an important treatment target to reduce the risk of relapse and improve patients' quality of life. Opioid agonist therapies (OAT), such as buprenorphine and methadone, can significantly reduce craving and relapse risk, and it is essential that patients are treated optimally with these therapies. There is also evidence to support the benefits of non-pharmacological approaches, such as cognitive behavioral therapy and mindfulness-based interventions, as supplementary treatments to opioid agonist therapies. However, despite the positive impact of these treatments on craving, many OUD patients continue to suffer with negative affect and dysphoria. There is a clear need for further studies to progress our understanding of the neurobiological basis of craving and addiction and to identify novel therapeutic strategies as well as to optimize the use of existing treatments to improve outcomes for the growing numbers of patients affected by OUD.

Autonomic and affective mediators of the relationship between mindfulness and opioid craving among chronic pain patients

Prescription opioid misuse among chronic pain patients is undergirded by self-regulatory deficits, affective distress, and opioid-cue reactivity. Dispositional mindfulness has been associated with enhanced self-regulation, lower distress, and adaptive autonomic responses following drug-cue exposure. We hypothesized that dispositional mindfulness might serve as a protective factor among opioid-treated chronic pain patients. We examined heart-rate variability (HRV) during exposure to opioid cues and depressed mood as mediators of the association between dispositional mindfulness and opioid craving. Data were obtained from a sample of chronic pain patients (N = 115) receiving long-term opioid pharmacotherapy. Participants self-reported opioid craving and depression, and HRV was measured during an opioid-cue dot-probe task. Dispositional mindfulness was significantly positively correlated with HRV, and HRV was significantly inversely associated with opioid craving. Dispositional mindfulness was significantly negatively correlated with depression, and depression was significantly positively correlated with opioid craving. Path analysis revealed significant indirect effects of dispositional mindfulness on craving through both HRV and depression. Dispositional mindfulness may buffer against opioid craving among chronic pain patients prescribed opioids; this buffering effect may be a function of improved autonomic and affective responses. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Exploring Exercise- and Context-Induced Peptide Changes in Mice by Quantitative Mass Spectrometry

Recent research suggests that exercise may help facilitate abstinence from cocaine addiction, though the mechanisms are not well understood. In mice, wheel running accelerates the extinction of conditioned place preference (CPP) for cocaine, providing an animal model for evaluating potential neurological mechanisms. The objective of this study was to quantify dynamic changes in endogenous peptides in the amygdala and dentate gyrus of the hippocampus in mice exposed to a context paired with the effects of cocaine, and in response to exercise. Male C57BL/6J mice conditioned to cocaine were housed with or without running wheels for 30 days. Following a CPP test and final exposure to either a cocaine- or saline-associated context, peptides were measured in brain tissue extracts using label-free matrix-assisted laser desorption/ionization mass spectrometry (MS) and stable isotopic labeling with liquid chromatography and electrospray ionization MS. CPP in mice was significantly reduced with running, which correlated to decreased myelin basic protein derivatives in the dentate gyrus extracts, possibly reflecting increased unmyelinated granule neuron density. Exposure to a cocaine-paired context increased hemoglobin-derived peptides in runners and decreased an actin-derived peptide in sedentary animals. These results allowed us to characterize a novel set of biomarkers that are responsive to exercise in the hippocampus and in a cocaine-paired context in the amygdala.

Gender moderates the association between distress tolerance and alcohol use among individuals with opioid use disorder

BACKGROUND

Alcohol use among individuals with opioid use disorder (OUD) can be dangerous, and understanding factors contributing to alcohol use in this population is important. The current study examined alcohol use among individuals with prescription OUD based on distress tolerance. It was hypothesized that individuals with greater distress tolerance abilities would have a lower frequency and quantity of alcohol use compared to individuals with less distress tolerance. It was also hypothesized that this association would differ based on gender.

METHODS

A total of 122 individuals with prescription OUD participated in the current study. Participants completed questionnaires regarding demographics, distress tolerance, mental health symptoms, and frequency and quantity of alcohol in the past 30 days. A regression model was conducted using the alcohol-related variables as outcomes.

RESULTS

There was a significant interaction between gender and distress tolerance on alcohol use frequency. Greater distress tolerance was associated with fewer alcohol use days in women, but there was no association between distress tolerance and alcohol use days in men.

CONCLUSIONS

The findings suggest that distress tolerance skills may be key to reducing alcohol use in women with prescription OUD.

Lorcaserin Suppresses Oxycodone Self-Administration and Relapse Vulnerability in Rats

Opioid use disorder (OUD) is a major public health problem. High relapse rates and poor treatment retention continue to pose major challenges in OUD treatment. Of the abused opioids, oxycodone is well described to maintain self-administration and evoke the durable conditioned responses ("cue reactivity") that result from pairing of opioid-related stimuli (e.g., paraphernalia) with repeated abuse. Serotonin (5-HT) neurotransmission, particularly through the 5-HT_2C receptor (5-HT_2CR), regulates psychostimulant reward and cue reactivity, and in the present experiments, we investigated the hypothesis that the selective 5-HT_2CR agonist lorcaserin, which is approved by the United States Food and Drug Administration (FDA) for the treatment of obesity, will suppress oxycodone self-administration and oxycodone-associated cue reactivity in rats. We found that lorcaserin inhibited oxycodone intake, an effect blocked by the selective 5-HT_2CR antagonist SB242084. Lorcaserin also decreased responding for the discrete cue complex ("cue reactivity") previously associated with delivery of oxycodone (i.e., stimulus lights, infusion pump sounds) in both abstinence and extinction-reinstatement models. The selected dose range of lorcaserin (0.25-1 mg/kg) does not overtly alter spontaneous behaviors nor operant responding on inactive levers in the present study. Taken together, the ability of lorcaserin to reduce the oxycodone self-administration and decrease cue reactivity associated with relapse highlights the therapeutic potential for lorcaserin in the treatment of OUD.

Laboratory-induced stress and craving among individuals with prescription opioid dependence

BACKGROUND

Stress and conditioned drug cues have been implicated in the initiation, maintenance and relapse to substances of abuse. Although stress and drug cues are often encountered together, little research exists on whether stress potentiates the response to drug cues.

METHOD

Participants (N=75) were 39 community recruited individuals with current prescription opioid (PO) dependence and 36 healthy controls. Participants stayed overnight in the hospital for one night and then completed laboratory testing the following morning. During laboratory testing, participants were randomly assigned to a stress task (Trier Social Stress Task; TSST) or a no-stress condition. Following the stress manipulation, all participants completed a PO cue paradigm. Immediately before and after the stress and cue tasks, the following were assessed: subjective (stress, craving, anger, sadness, happiness), physiological (heart rate, blood pressure, galvanic skin response), and neuroendocrine responses (cortisol and dehydroepiandrosterone).

RESULTS

Internal validity of the stress task was demonstrated, as evidenced by significantly higher subjective stress, as well as cortisol, heart rate and blood pressure in the TSST compared to the no-stress group. Individuals with PO dependence evidenced significantly greater reactivity to the stress task than controls. Craving increased significantly in response to the drug cue task among PO participants. No stress×cue interaction was observed.

CONCLUSIONS

In this study, heightened stress reactivity was observed among individuals with PO dependence. Exposure to acute stress, however, did not potentiate craving in response to conditioned drug cues.

The attribution of incentive salience to Pavlovian alcohol cues: a shift from goal-tracking to sign-tracking

Environmental stimuli that are reliably paired with alcohol may acquire incentive salience, a property that can operate in the use and abuse of alcohol. Here we investigated the incentive salience of Pavlovian alcohol cues using a preclinical animal model. Male, Long-Evans rats (Harlan) with unrestricted access to food and water were acclimated to drinking 15% ethanol (v/v) in their home-cages. Rats then received Pavlovian autoshaping training in which the 10 s presentation of a retractable lever served as the conditioned stimulus (CS) and 15% ethanol served as the unconditioned stimulus (US) (0.2 ml/CS; 12 CS presentations/session; 27 sessions). Next, in an operant test of conditioned reinforcement, nose pokes into an active aperture delivered presentations of the lever-CS, whereas nose pokes into an inactive aperture had no consequences. Across initial autoshaping sessions, goal-tracking behavior, as measured by entries into the fluid port where ethanol was delivered, developed rapidly. However, with extended training goal-tracking diminished, and sign-tracking responses, as measured by lever-CS activations, emerged. Control rats that received explicitly unpaired CS and US presentations did not show goal-tracking or sign-tracking responses. In the test for conditioned reinforcement, rats with CS-US pairings during autoshaping training made more active relative to inactive nose pokes, whereas rats in the unpaired control group did not. Moreover, active nose pokes were positively correlated with sign-tracking behavior during autoshaping. Extended training may produce a shift in the learned properties of Pavlovian alcohol cues, such that after initially predicting alcohol availability they acquire robust incentive salience.

Physiological indicators of pathologic video game use in adolescence

PURPOSE

Pathologic video game use (PVGU) has been associated with a host of negative psychological, physical, and social outcomes during adolescence; however, little research has examined physiological predictors of such use. The purpose of the study was to examine physiological predictors of the development of PVGU across adolescence.

METHODS

The article involves a 1-year longitudinal study across midadolescence. Participants were 374 adolescents and their parents from a large metropolitan area in the Northwest United States. PVGU was assessed via questionnaire, as were a number of control variables. A number of physiological indicators including respiratory sinus arrhythmia (RSA) and galvanic skin conductance (indices of parasympathetic and sympathetic nervous system activity, respectively) were measured during baseline, a cognitively stimulating task (Rubik's cube), and a family problem-solving task.

RESULTS

Less RSA withdrawal to a cognitively simulating task was related to greater pathologic video game symptoms, but less RSA withdrawal to a family problem-solving task was associated with the presence of pathologic video game symptoms (p < .05). For girls only, galvanic skin conductance activation during the family problem solving was related to greater pathologic video game symptoms (p < .01).

CONCLUSIONS

These findings suggest that adolescents who do not find cognitive tasks stimulating physiologically have a greater severity of PVGU. Additionally, adolescents who show physiological signs of stress in a family task were more likely to have PVGU symptoms and only girls have more severe PVGU levels. This study is the first to show that physiological indicators predict PVGU over time in adolescence and has important implications regarding the prevention and treatment of PVGU in adolescence.