Allostatic dysregulation of natural reward processing in prescription opioid misuse: autonomic and attentional evidence

Heart Rate Variability in Adults With Substance Use Disorder: A Comprehensive Narrative Review

BACKGROUND

Heart rate variability (HRV) is an indicator of autonomic abnormalities. However, little is known about the role of HRV related to substance use behavior and the association between the changes in HRV and signs of relapse in substance use.

AIM

The purpose of this study was to review the existing literature on autonomic response to substance use (i.e., opioids, cocaine, and methamphetamine) measured by HRV and its outcomes related to the risk factors of relapse.

METHODS

A systematic search of the literature was conducted using PubMed, PsychINFO, and Ovid Medline databases. The study includes full-text articles published in English from 2010 to 2020, using measures of HRV in human subjects who use substances.

RESULTS

A total of 14 studies were reviewed. Studies included outpatients with a prescription or nonprescription opioid misuse behavior with a primary diagnosis being chronic pain or substance use disorder (SUD). Significantly decreased resting HRV was found in substance users compared to healthy controls. Lower resting HRV has been significantly associated with stress, craving, and greater symptom severities in individuals with SUD and other substance dependence. HRV indices can be potential measures of homeostatic imbalance and self-regulation flexibility.

CONCLUSION

HRV may be a useful tool for monitoring early indication of relapse so that relapse prevention measures can be implemented in a timely manner. Future studies in substance use may benefit from examining HRV in relations to substance use and relapse signs and symptoms in a larger population to guide future relapse prevention strategies.

Restructuring reward: A pilot study to enhance natural reward response in adults with cannabis use disorder

BACKGROUND

Hedonic dysregulation is a core mechanism of addiction. There is a dearth of research on hedonic dysregulation in cannabis use disorder (CUD). The current study tested whether personalized scripted imagery may be an efficacious approach to remediate reward functioning in adults with CUD.

METHODS

Adults with CUD (n=10) and non-CUD controls (n=12) completed a single session personalized scripted imagery procedure. Non-drug (i.e. natural) reward and neutral scripts were transcribed and participants listened to the scripts in counterbalanced order. Primary outcomes included positive affect (PA), galvanic skin response (GSR), and cortisol and were assessed at four timepoints. Mixed effects models were used to compare between and within subject effects.

RESULTS

Mixed effects models revealed a Condition (reward vs. neutral) X Group (CUD vs. control) interaction (p=0.01) on PA response, indicating blunted PA response to the neutral script relative to the reward script in CUD participants. Likewise, GSR response in CUD participants was decreased in response to the neutral script relative to the reward script (p=0.034; interaction n.s.). An interaction effect of Group X PA on cortisol response was found (p=.036) indicating that cortisol was positively correlated with PA in healthy control participants, but not CUD participants.

CONCLUSIONS

Adults with CUD may demonstrate acute deficits in hedonic tone under neutral conditions relative to healthy controls. Personalized scripted imagery may be an efficacious tool to remediate hedonic dysregulation in CUD. Cortisol may play a role in healthy positive affect regulation warranting further investigation.

Mindfulness-Oriented Recovery Enhancement remediates anhedonia in chronic opioid use by enhancing neurophysiological responses during savoring of natural rewards

BACKGROUND

Neuropsychopharmacologic effects of long-term opioid therapy (LTOT) in the context of chronic pain may result in subjective anhedonia coupled with decreased attention to natural rewards. Yet, there are no known efficacious treatments for anhedonia and reward deficits associated with chronic opioid use. Mindfulness-Oriented Recovery Enhancement (MORE), a novel behavioral intervention combining training in mindfulness with savoring of natural rewards, may hold promise for treating anhedonia in LTOT.

METHODS

Veterans receiving LTOT (N = 63) for chronic pain were randomized to 8 weeks of MORE or a supportive group (SG) psychotherapy control. Before and after the 8-week treatment groups, we assessed the effects of MORE on the late positive potential (LPP) of the electroencephalogram and skin conductance level (SCL) during viewing and up-regulating responses (i.e. savoring) to natural reward cues. We then examined whether these neurophysiological effects were associated with reductions in subjective anhedonia by 4-month follow-up.

RESULTS

Patients treated with MORE demonstrated significantly increased LPP and SCL to natural reward cues and greater decreases in subjective anhedonia relative to those in the SG. The effect of MORE on reducing anhedonia was statistically mediated by increases in LPP response during savoring.

CONCLUSIONS

MORE enhances motivated attention to natural reward cues among chronic pain patients on LTOT, as evidenced by increased electrocortical and sympathetic nervous system responses. Given neurophysiological evidence of clinical target engagement, MORE may be an efficacious treatment for anhedonia among chronic opioid users, people with chronic pain, and those at risk for opioid use disorder.

Association between opioid use disorder and blunted heart rate variability among opioid-treated chronic pain patients

Given the severity of the ongoing opioid epidemic, it is essential to understand the mechanisms of risk for development and maintenance of opioid use disorder (OUD). The aim of the current large-scale psychophysiological investigation was to test whether patients with OUD had lower resting-state high-frequency heart rate variability (HF-HRV) than those without OUD, controlling for sociodemographic and clinical confounds. Additionally, we tested whether HF-HRV was associated with opioid craving in this population. Participants in this cross-sectional study were 490 chronic pain patients (50.4% female) treated with long-term opioid therapy. OUD diagnosis was determined by psychiatric interview. HF-HRV was measured at resting baseline. We computed the association between OUD and resting-state HF-HRV, controlling for age, gender, race, pain severity, emotional distress and opioid dose. Opioid craving was measured with visual analogue scales to assess whether HF-HRV was associated with craving. Results showed that resting HF-HRV was significantly lower for patients with OUD than for those without OUD (p < 0.001, d = 0.36), indicating deficits in autonomic flexibility. OUD diagnosis (p = 0.002) and OUD severity (p = 0.03) were associated with lower HF-HRV in regression models accounting for a range of confounders. Additionally, lower HF-HRV was significantly (but weakly) correlated with heightened opioid craving (r = -0.166, p < 0.001). Overall, findings suggest that resting-state HF-HRV may serve as a valid biomarker of addiction among people on long-term opioid therapy.

Prefrontal cortical response to natural rewards and self-reported anhedonia are associated with greater craving among recently withdrawn patients in residential treatment for opioid use disorder

Both anhedonia and craving are common among patients with opioid use disorder (OUD), and are associated with vulnerability to relapse. Although these constructs are theoretically linked relatively few studies have examined them together. In the current study, recently withdrawn patients (N = 71) in residential treatment for prescription OUD underwent a cue reactivity paradigm while being monitored with functional near-infrared spectroscopy (fNIRS). Patients also self-reported symptoms of anhedonia via the Snaith-Hamilton Pleasure Scale (SHAPS), while smartphone-based ecological momentary assessments (EMA) were used to measure craving levels. On average, lower right prefrontal cortex (PFC) activity in response to positive social stimuli was associated with higher craving (β = - 2.87; S.E. = 1.23; p = 0.02). Self-reported anhedonia moderated the association between PFC activity and craving (β = - 1.02; S.E. = 0.48; p = 0.04), such that patients with two or more anhedonic symptoms had a significant and stronger negative association between PFC activation to hedonically positive images and craving, compared to patients with fewer than two anhedonic symptoms, among whom the association was not significant. This finding provides evidence that higher levels of anhedonia among patients in residential treatment for OUD are associated with a stronger link between lower PFC response to positive social experiences and higher levels of craving, potentially increasing overall vulnerability to relapse.

Simulated opioid choice linked to opioid use disorder severity among veterans with chronic pain: initial validation of a novel paradigm

Background: Modeling addictive behavior among individuals with, or at risk for, opioid use disorder (OUD) in a way that is accurate, ethical, and reproducible presents a pressing concern. OUD risk is elevated among people with chronic pain on long-term opioid therapy (LTOT).Objectives: To provide initial validation of a novel opioid preference task as an index of OUD and its symptomatology among veterans prescribed opioids for chronic pain, a population at high risk for poor opioid-related outcomes. The relative ease by which such a paradigm can be implemented and performed in clinical contexts, including enabling investigation of opioid reinforcement and drug-seeking behavior while avoiding ethical pitfalls associated with direct drug administration, could make this task an attractive approach for potentially tracking OUD symptoms.Methods: We studied 87 veterans (74 males, 13 females) on LTOT for chronic pain - 33 of whom had OUD diagnoses. Participants completed a picture-viewing choice task to assess preference for viewing opioid-related images in comparison with standardized pleasant, unpleasant, neutral, and blank images. Opioid-related choice, measured by vigor of button pressing, was tested for association with OUD severity (measured by symptom counts), as well as craving and anhedonia.Results: Choice for opioid-related images was positively correlated with OUD severity (i.e., number of DSM-5 measured OUD symptoms) (r = 0.38, p < .001), particularly among those meeting diagnostic criteria for OUD (r = 0.47, p = .006). Neither craving nor anhedonia correlated with opioid-related choice.Conclusions: Our results provide initial validation for a new opioid picture-choice paradigm in patients with chronic pain.

Arguments for and Against a New Diagnostic Entity for Patients With Chronic Pain on Long-Term Opioid Therapy for Whom Harms Outweigh Benefits

The goal of this study was to understand perspectives on whether a new diagnostic entity, distinct from Diagnostic and Statistical Manual - 5 (DSM-5) opioid use disorder (OUD), is needed for patients with chronic pain on long-term opioid therapy (LTOT) for whom the harms of continued opioid therapy outweigh the benefits. Data were collected as part of a larger Delphi study. We used rapid and thematic qualitative methods to analyze data from 51 panelists with expertise in internal medicine, psychiatry, psychology, and related fields. Three-quarters of panelists supported a new diagnostic entity; common themes included recognizing distinct experiences of patients prescribed LTOT, addressing problems with DSM-5 OUD criteria, facilitating research and improved treatment, and reducing stigma. Thirteen panelists opposed the creation of a new diagnostic entity; common themes included similarities in biological underpinnings of patients prescribed LTOT and diagnosed with OUD, belief that the continuum of OUD captured patients' experiences, finding better ways to address problems with DSM-5 OUD criteria, and concerns about stigma. While this expert panel disagreed about the need for a new diagnostic entity, there was an overall acknowledgement that the current implementation of DSM-5's OUD diagnosis is not meeting the needs of LTOT providers or patients. PERSPECTIVE: The DSM-5's OUD diagnosis may not adequately meet the needs of patients on LTOT for whom the harms of continued opioid therapy outweigh the benefits. Experts do not agree on how to address this problem; more work is needed to determine if a new diagnostic entity would be beneficial.

Emotional distress and pain catastrophizing predict cue-elicited opioid craving among chronic pain patients on long-term opioid therapy

BACKGROUND

Individuals who use illicit substances exhibit cue-elicited craving and autonomic cue-reactivity when exposed to cues associated with past drug use. However, little is known about this phenomenon among chronic pain patients on long-term opioid therapy (LTOT). Negative cognitive-emotional reactivity in general (e.g., distress) and cognitive-emotional reactivity specific to pain (e.g., pain catastrophizing) might drive cue-reactivity independent of pain severity. Here we examined emotional distress and pain catastrophizing as predictors of cue-reactivity among a sample of chronic pain patients receiving LTOT. We also tested whether associations between distress, catastrophizing, and cue-reactivity differed as a function of opioid misuse status.

MATERIALS AND METHODS

Patients receiving LTOT (N = 243) were classified as exhibiting aberrant behavior consistent with opioid misuse (MISUSE+, n = 145) or as using opioids as prescribed (MISUSE-, n = 97). Participants completed assessments of pain catastrophizing and emotional distress and then participated in an opioid cue-reactivity task one week later. Cue-elicited opioid craving and autonomic cue-reactivity were measured with craving ratings and high-frequency heart rate variability (HRV), respectively.

RESULTS

Distress and catastrophizing predicted cue-elicited craving and HRV, whereas pain severity did not. Misuser status moderated the relationship between emotional distress and self-reported craving, such that higher levels of distress predicted craving among the MISUSE+ group, but not among the MISUSE- group. No moderating effects were found for catastrophizing.

CONCLUSIONS

Findings suggest that although opioids are prescribed for analgesia, the exacerbating influence of negative cognitive-emotional reactivity, both in general and specific to pain, on cue-elicited opioid craving extends beyond the effects of pain severity alone.

Mind-body approaches targeting the psychological aspects of opioid use problems in patients with chronic pain: evidence and opportunities

Opioids are commonly prescribed for the management of patients with chronic noncancer pain. Despite the potential analgesic benefits of opioids, long-term opioid therapy (LTOT) may be accompanied by problems such as opioid misuse and opioid use disorder (OUD). In this review, we begin with a description of opioid misuse and OUD and the patient-specific factors associated with these problems among patients with chronic pain. We will focus primarily on highlighting the predominant role played by psychological factors in the occurrence of opioid misuse and OUD in these patients. Several psychological factors have been found to be associated with opioid use problems in patients with chronic pain, and evidence indicates that patients presenting with psychological disturbances are particularly at risk of transitioning to long-term opioid use, engaging in opioid misuse behaviors, and developing OUD. The biological factors that might underlie the association between psychological disturbances and opioid use problems in patients with chronic pain have yet to be fully elucidated, but a growing number of studies suggest that dysfunctions in reward, appetitive, autonomic, and neurocognitive systems might be involved. We end with an overview of specific types of psychological interventions that have been put forward to prevent or reduce the occurrence of opioid misuse and OUD in patients with chronic pain who are prescribed LTOT.

Mindful Positive Emotion Regulation as a Treatment for Addiction: From Hedonic Pleasure to Self-Transcendent Meaning

Chronic drug use is theorized to induce cortico-striatal neuroplasticity, driving an allostatic process marked by increased sensitivity to drug-related cues and decreased sensitivity to natural rewards that results in anhedonia and a dearth of positive affect. As such, positive emotion regulation represents a key mechanistic target for addictions treatment. This paper provides a conceptual model detailing how mindfulness may synergize a range of positive affective mechanisms to reduce addictive behavior, from savoring the hedonic pleasure derived from natural rewards, to self-generating interoceptive reward responses, and ultimately to cultivating self-transcendent meaning. These therapeutic processes may restructure reward processing from over-valuation of drug-related rewards back to valuation of natural rewards, and hypothetically, "reset" the default mode network dysfunction that undergirds addiction.

The Role of Mu-Opioids for Reward and Threat Processing in Humans: Bridging the Gap from Preclinical to Clinical Opioid Drug Studies

PURPOSE OF REVIEW

Opioid receptors are widely expressed in the human brain. A number of features commonly associated with drug use disorder, such as difficulties in emotional learning, emotion regulation and anhedonia, have been linked to endogenous opioid signalling. Whereas chronic substance use and misuse are thought to alter the function of the mu-opioid system, the specific mechanisms are not well understood. We argue that understanding exogenous and endogenous opioid effects in the healthy human brain is an essential foundation for bridging preclinical and clinical findings related to opioid misuse. Here, we will examine psychopharmacological evidence to outline the role of the mu-opioid receptor (MOR) system in the processing of threat and reward, and discuss how disruption of these processes by chronic opioid use might alter emotional learning and reward responsiveness.

RECENT FINDINGS

In healthy people, studies using opioid antagonist drugs indicate that the brain's endogenous opioids downregulate fear reactivity and upregulate learning from safety. At the same time, endogenous opioids increase the liking of and motivation to engage with high reward value cues. Studies of acute opioid agonist effects indicate that with non-sedative doses, drugs such as morphine and buprenorphine can mimic endogenous opioid effects on liking and wanting. Disruption of endogenous opioid signalling due to prolonged opioid exposure is associated with some degree of anhedonia to non-drug rewards; however, new results leave open the possibility that this is not directly opioid-mediated.

SUMMARY

The available human psychopharmacological evidence indicates that the healthy mu-opioid system contributes to the regulation of reward and threat processing. Overall, endogenous opioids can subtly increase liking and wanting responses to a wide variety of rewards, from sweet tastes to feelings of being connected to close others. For threat-related processing, human evidence suggests that endogenous opioids inhibit fear conditioning and reduce the sensitivity to aversive stimuli, although inconsistencies remain. The size of effects reported in healthy humans are however modest, clearly indicating that MORs play out their role in close concert with other neurotransmitter systems. Relevant candidate systems for future research include dopamine, serotonin and endocannabinoid signalling. Nevertheless, it is possible that endogenous opioid fine-tuning of reward and threat processing, when unbalanced by e.g. opioid misuse, could over time develop into symptoms associated with opioid use disorder, such as anhedonia and depression/anxiety.

Prescription opioid misusers exhibit blunted parasympathetic regulation during inhibitory control challenge

RATIONALE

Among opioid-treated chronic pain patients, response inhibition deficits in emotional contexts may contribute to opioid misuse.

OBJECTIVES

Using high-frequency heart rate variability (HF-HRV) to index-impaired response inhibition, we examined associations between opioid misuse and response inhibition in emotional and neutral contexts in a sample of opioid-treated chronic pain patients.

METHOD

Chronic pain patients taking opioid analgesics (N = 97) for ≥ 90 days completed an Emotional Go/NoGo task that presented an inhibitory control challenge in the context of neutral, opioid, negative affective, and positive affective background images while HF-HRV was computed. Opioid misuse and craving were assessed. Using a validated cut-point on the Current Opioid Misuse Measure, participants were classified as opioid misusers or non-misusers. Opioid misuse was examined as a predictor of behavioral and HF-HRV metrics of response inhibition.

RESULTS

Negative affective and opioid images elicited more errors of commission (p = .002, η²_partial = .16) and slowed reaction times (p = .045, η²_partial = .09) compared to neutral and positive affective images, respectively. Though no between-group behavioral differences were observed on the task, opioid misusers exhibited significantly blunted phasic HF-HRV during the task relative to non-misusers (p = .027, η²_partial = .11). HF-HRV during the task was significantly inversely associated with opioid craving. It was not clear whether these autonomic findings reflected a durable phenotypic difference between groups or between-group differences in opioid dosing and withdrawal.

CONCLUSION

Reduced parasympathetic regulation during inhibitory control challenge may indicate heightened opioid misuse risk among opioid-treated chronic pain patients.

The temporal dynamics of emotion dysregulation in prescription opioid misuse

BACKGROUND

Opioid misuse is theorized to compromise the capacity to regulate positive and negative emotions. Yet, the temporal dynamics of emotion dysregulation in opioid misuse remain unclear.

METHODS

Patients with chronic pain on long-term opioid therapy (N = 71) participated in an experiment in which they completed an event-related emotion regulation task while heart rate (HR) and galvanic skin responses (GSR) were recorded over a 5 s emotional picture viewing period. Participants were asked to passively view the images or to proactively regulate their emotional responses via reappraisal (i.e., negative emotion regulation) and savoring (i.e., positive emotion regulation) strategies. Using a validated cutpoint on the Current Opioid Misuse Measure, participants were classified as medication-adherent or opioid misusers.

RESULTS

Medication-adherent patients were able to significantly decrease GSR and HR during negative emotion regulation, whereas opioid misusers exhibited contradictory increases in these autonomic parameters during negative emotion regulation. Furthermore, GSR during positive emotion regulation increased for non-misusers, whereas GSR during positive emotion regulation did not increase for misusers. These autonomic differences, which remained significant even after controlling for a range of covariates, were evident within 1 s of emotional stimulus presentation but reached their maxima 3-4 s later.

CONCLUSIONS

Opioid misuse among people with chronic pain is associated with emotion dysregulation that occurs within the first few seconds of an emotional provocation. Treatments for opioid misuse should aim to remediate these deficits in emotion regulation.

A mu-opioid feedback model of human social behavior

Since the discovery of pain relieving and rewarding properties of opiates such as morphine or heroin, the human mu-opioid system has been a target for medical research on pain processing and addiction. Indeed, pain and pleasure act mutually inhibitory on each other and the mu-opioid system has been suggested as an underlying common neurobiological mechanism. Recently, research interest extended the role of the endogenous mu-opioid system beyond the hedonic value of pain and pleasure towards human social-emotional behavior. Here we propose a mu-opioid feedback model of social behavior. This model is based upon recent findings of opioid modulation of human social learning, bonding and empathy in relation to affiliative and protective tendencies. Fundamental to the model is that the mu-opioid system reinforces socially affiliative or protective behavior in response to positive and negative social experiences with long-term consequences for social behavior and health. The functional implications for stress, anxiety, depression and attachment behaviors are discussed.

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.

Anhedonia in chronic pain and prescription opioid misuse

BACKGROUND

Both acute and chronic pain can disrupt reward processing. Moreover, prolonged prescription opioid use and depressed mood are common in chronic pain samples. Despite the prevalence of these risk factors for anhedonia, little is known about anhedonia in chronic pain populations.

METHODS

We conducted a large-scale, systematic study of anhedonia in chronic pain, focusing on its relationship with opioid use/misuse, pain severity, and depression. Chronic pain patients across four distinct samples (N = 488) completed the Snaith-Hamilton Pleasure Scale (SHAPS), measures of opioid use, pain severity and depression, as well as the Current Opioid Misuse Measure (COMM). We used a meta-analytic approach to determine reference levels of anhedonia in healthy samples spanning a variety of countries and diverse age groups, extracting SHAPS scores from 58 published studies totaling 2664 psychiatrically healthy participants.

RESULTS

Compared to healthy samples, chronic pain patients showed higher levels of anhedonia, with ~25% of patients scoring above the standard anhedonia cut-off. This difference was not primarily driven by depression levels, which explained less than 25% of variance in anhedonia scores. Neither opioid use duration, dose, nor pain severity alone was significantly associated with anhedonia. Yet, there was a clear effect of opioid misuse, with opioid misusers (COMM ⩾13) reporting greater anhedonia than non-misusers. Opioid misuse remained a significant predictor of anhedonia even after controlling for pain severity, depression and opioid dose.

CONCLUSIONS

Study results suggest that both chronic pain and opioid misuse contribute to anhedonia, which may, in turn, drive further pain and misuse.

Mindfulness-oriented recovery enhancement reduces opioid dose in primary care by strengthening autonomic regulation during meditation

The current opioid crisis was fueled by escalation of opioid dosing among patients with chronic pain. Yet, there are few evidence-based psychological interventions for opioid dose reduction among chronic pain patients treated with long-term opioid analgesics. Mindfulness-Oriented Recovery Enhancement (MORE), which was designed to target mechanisms underpinning chronic pain and opioid misuse, has shown promising results in 2 randomized clinical trials (RCTs) and could facilitate opioid sparing and tapering by bolstering self-regulation. Here we tested this hypothesis with secondary analyses of data from a Stage 2 RCT. Chronic pain patients (N = 95) on long-term opioid therapy were randomized to 8 weeks of MORE or a support group (SG) control delivered in primary care. Opioid dose was assessed with the Timeline Followback through 3-month follow-up. Heart rate variability (HRV) during mindfulness meditation was quantified as an indicator of self-regulatory capacity. Participants in MORE evidenced a greater decrease in opioid dosing (a 32% decrease) by follow-up than did the SG, F(2, 129.77) = 5.35, p = .006, d = 1.07. MORE was associated with a significantly greater increase in HRV during meditation than was the SG. Meditation-induced change in HRV partially mediated the effect of MORE on opioid dose reduction (p = .034). MORE may boost self-regulatory strength via mindfulness and thereby facilitate self-control over opioid use, leading to opioid dose reduction in people with chronic pain. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Behavioral preference for viewing drug v. pleasant images predicts current and future opioid misuse among chronic pain patients

BACKGROUND

The USA is currently enduring an opioid crisis. Identifying cost-effective, easy-to-implement behavioral measures that predict treatment outcomes in opioid misusers is a crucial scientific, therapeutic, and epidemiological goal.

METHODS

The current study used a mixed cross-sectional and longitudinal design to test whether a behavioral choice task, previously validated in stimulant users, was associated with increased opioid misuse severity at baseline, and whether it predicted change in opioid misuse severity at follow-up. At baseline, data from 100 prescription opioid-treated chronic pain patients were analyzed; at follow-up, data were analyzed in 34 of these participants who were non-misusers at baseline. During the choice task, participants chose under probabilistic contingencies whether to view opioid-related images in comparison with affectively pleasant, unpleasant, and neutral images. Following previous procedures, we also assessed insight into choice behavior, operationalized as whether (yes/no) participants correctly self-reported the image category they chose most often.

RESULTS

At baseline, the higher choice for viewing opioid images in direct comparison with pleasant images was associated with opioid misuse and impaired insight into choice behavior; the combination of these produced especially elevated opioid-related choice behavior. In longitudinal analyses of individuals who were initially non-misusers, higher baseline opioid v. pleasant choice behavior predicted more opioid misuse behaviors at follow-up.

CONCLUSIONS

These results indicate that greater relative allocation of behavior toward opioid stimuli and away from stimuli depicting natural reinforcement is associated with concurrent opioid misuse and portends vulnerability toward future misuse. The choice task may provide important medical information to guide opioid-prescribing practices.

Impaired frontostriatal functional connectivity among chronic opioid using pain patients is associated with dysregulated affect

Preclinical studies have shown effects of chronic exposure to addictive drugs on glutamatergic-mediated neuroplasticity in frontostriatal circuitry. These initial findings have been paralleled by human functional magnetic resonance imaging (fMRI) research demonstrating weaker frontostriatal resting-state functional connectivity (rsFC) among individuals with psychostimulant use disorders. However, there is a dearth of human imaging literature describing associations between long-term prescription opioid use, frontostriatal rsFC, and brain morphology among chronic pain patients. We hypothesized that prescription opioid users with chronic pain, as compared with healthy control subjects, would evidence weaker frontostriatal rsFC coupled with less frontostriatal gray matter volume (GMV). Further, those opioid use-related deficits in frontostriatal circuitry would be associated with negative affect and drug misuse. Prescription opioid users with chronic pain (n = 31) and drug-free healthy controls (n = 30) underwent a high-resolution anatomical and an eyes-closed resting-state functional scan. The opioid group, relative to controls, exhibited weaker frontostriatal rsFC, and less frontostriatal GMV in both L.NAc and L.vmPFC. Frontostriatal rsFC partially mediated group differences in negative affect. Within opioid users, L.NAc GMV predicted opioid misuse severity. The current study revealed that prescription opioid use in the context of chronic pain is associated with functional and structural abnormalities in frontostriatal circuitry. These results suggest that opioid use-related abnormalities in frontostriatal circuitry may undergird disturbances in affect that may contribute to the ongoing maintenance of opioid use and misuse. These findings warrant further examination of interventions to treat opioid pathophysiology in frontostriatal circuitry over the course of treatment.

Sensor Technologies to Manage the Physiological Traits of Chronic Pain: A Review

Non-oncologic chronic pain is a common high-morbidity impairment worldwide and acknowledged as a condition with significant incidence on quality of life. Pain intensity is largely perceived as a subjective experience, what makes challenging its objective measurement. However, the physiological traces of pain make possible its correlation with vital signs, such as heart rate variability, skin conductance, electromyogram, etc., or health performance metrics derived from daily activity monitoring or facial expressions, which can be acquired with diverse sensor technologies and multisensory approaches. As the assessment and management of pain are essential issues for a wide range of clinical disorders and treatments, this paper reviews different sensor-based approaches applied to the objective evaluation of non-oncological chronic pain. The space of available technologies and resources aimed at pain assessment represent a diversified set of alternatives that can be exploited to address the multidimensional nature of pain.

Co-designing a Mobile Gamified Attention Bias Modification Intervention for Substance Use Disorders: Participatory Research Study

Background

Advances in experimental psychology have highlighted the need to modify underlying automatic cognitive biases, such as attentional biases. The effectiveness of bias modification has been well studied for substance use disorders. With recent advances in technology, it is now possible to work outside the laboratory with Web-based and mobile-based attention bias interventions. Gamification technologies might also help diminish the repetitiveness of the task and increase the intrinsic motivation to train. The inconsistent findings of the impact of gaming on the effectiveness of mobile interventions call for further work to better understand the needs of patients (users) and health care professionals.

Objective

The aim of this study was to involve patients, together with health care professionals, in the design of a gamified mobile attention bias modification intervention for substance use disorders.

Methods

The participatory design research method adopted is that of a user-oriented design approach in the form of a future workshop. In the first phase of the workshop, participants shared their critique of an attention bias modification intervention. In the second phase of the workshop, participants were asked to brainstorm features. Participants were also shown gamification approaches and asked to consider if gaming elements could enhance the existing app. In the last phase, participants were asked to sketch a new prototype.

Results

Three co-design workshops were conducted with health care professionals, inpatients, and outpatients. There were 20 participants, consisting of 10 health care professionals and 10 patients. When asked to identify the limitations in the existing app, common issues identified were those of the design, visual probe task, and the included images. Outpatients were also concerned with the safety of administration of the intervention. In the brainstorming sessions, health care professionals made recommendations as to how the stimulus, the mechanism of responding, and the presentation of the scores could be enhanced. Inpatient participants recommended the addition of functionalities, such as information on the harms associated with the substance use, and for there to be enhancements in the design, images, and task. Outpatient participants perceived a need to improve the images and presentation of the results and recommended the inclusion of gaming features. There were differences in opinion on the inclusion of gaming features, as only health care professionals endorsed their inclusion. In the last phase of the workshop, participants were tasked with the conceptualization of prototypes, and the commonality in the design was for a gradual shortening of the interval for stimulus/image presentation.

Conclusions

The results from this research will guide the development of an app that meets the specific needs of patients and is still based on a pre-existing validated task paradigm.  

Variations in the Visual Probe Paradigms for Attention Bias Modification for Substance Use Disorders

Advances in experimental psychology have provided evidence for the presence of attentional and approach biases in individuals with substance use disorders. Traditionally, reaction time tasks, such as the Stroop or the Visual Probe Task, are commonly used in the assessment of attention biases. The Visual Probe Task has been criticized for its poor reliability, and other research has highlighted that variations remain in the paradigms adopted. However, a gap remains in the published literature, as there have not been any prior studies that have reviewed stimulus timings for different substance use disorders. Such a review is pertinent, as the nature of the task might affect its effectiveness. The aim of this paper was in comparing the different methods used in the Visual Probe Task, by focusing on tasks that have been used for the most highly prevalent substance disorders—that of opiate use, cannabis use and stimulant use disorders. A total of eight published articles were identified for opioid use disorders, three for cannabis use disorders and four for stimulant use disorders. As evident from the synthesis, there is great variability in the paradigm adopted, with most articles including only information about the nature of the stimulus, the number of trials, the timings for the fixation cross and the timings for the stimulus set. Future research examining attentional biases among individuals with substance use disorders should take into consideration the paradigms that are commonly used and evaluate the optimal stimulus and stimulus-onset asynchrony timings.

Mapping the Affective Dimension of Embodiment With the Sensation Manikin: Validation Among Chronic Pain Patients and Modification by Mindfulness-Oriented Recovery Enhancement

OBJECTIVE

Mindfulness-based interventions target novel pain relief mechanisms not captured by legacy pain scales, including 1) cultivating awareness of pleasant and neutral sensations proximal to unpleasant sensations and 2) interoceptively mapping sensation location and spatial distribution.

METHODS

We created a digital sensation manikin (SM) by overlaying a human figure silhouette with a grid of 469 "sensation" pixels. A series of five research questions examined the SM's discriminant validity, construct validity, incremental validity, convergence with an objective measure of pain attentional bias, and sensitivity to a mindfulness-based psychological treatment, Mindfulness-Oriented Recovery Enhancement (MORE). A sample of opioid treated chronic pain patients (n = 108; age, 53.79 (12.94) years; female, 65%) was recruited to answer research questions 1 to 5, and a sample of healthy controls (n = 91; age, 36.47 (13.50) years; female, 55%) was recruited as the comparison group for research question 1.

RESULTS

Chronic pain patients reported significantly more unpleasant sensations than did healthy controls (p < .001, d = 1.23) and significantly fewer pleasant sensations (p = .001, d = 0.50). The SM also evidenced expected relationships with multiple measures of pain (r = 0.26-0.29) and well-being (r = -0.21 to 0.28), uniquely predicted pain interference (β = -0.18), and exhibited a significant association with pain attentional bias (r = 0.25). Finally, mindfulness-based intervention via MORE significantly increased the ratio of pleasant to unpleasant sensations reported by chronic pain patients relative to an active control condition (p = .036, d = 0.51).

CONCLUSIONS

This study supports the SM's validity and indicates that assessing both pleasant and unpleasant sensations broadens the scope of pain measurement. Although the SM would benefit from further optimization, its continued use is likely to contribute to improved assessment and treatment options for chronic pain patients.

Intact responses to non-drug rewards in long-term opioid maintenance treatment

Disruption of non-drug reward processing in addiction could stem from long-term drug use, addiction-related psychosocial stress, or a combination of these. It remains unclear whether long-term opioid maintenance treatment (OMT) disrupts reward processing. Here, we measured subjective and objective reward responsiveness in 26 previously heroin-addicted mothers in >7 years stable OMT with minimal psychosocial stress and illicit drug use. The comparison group was 30 healthy age-matched mothers (COMP). Objective reward responsiveness was assessed in a two-alternative forced-choice task with skewed rewards. Results were also compared to performance from an additional 968 healthy volunteers (meta-analytic approach). We further compared subprocesses of reward-based decisions across groups using computational modelling with a Bayesian drift diffusion model of decision making. Self-reported responsiveness to non-drug rewards was high for both groups (means: OMT = 6.59, COMP = 6.67, p = 0.84, BF10 = 0.29), yielding moderate evidence against subjective anhedonia in this OMT group. Importantly, the mothers in OMT also displayed robust reward responsiveness in the behavioral task (t19 = 2.72, p = 0.013, BF10 = 3.98; d = 0.61). Monetary reward changed their task behavior to the same extent as the local comparison group (reward bias OMT = 0.12, COMP = 0.12, p = 0.96, BF10 = 0.18) and in line with data from 968 healthy controls previously tested. Computational modelling revealed that long-term OMT did not even change decision subprocesses underpinning reward behavior. We conclude that reduced sensitivity to rewards and anhedonia are not necessary consequences of prolonged opioid use.

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).

Attentional bias in opioid users: A systematic review and meta-analysis

BACKGROUND

Opioid use in the United States is a national public health emergency. The primary treatment for opioid use disorder (OUD) is medication assisted treatment (MAT). Although effective in improving treatment outcomes in OUD, there is a need to develop behavioral treatments adjunctive to MAT. The current study investigates attentional bias in OUD as a possible target for adjunctive behavioral treatments.

METHODS

Comprehensive literature searches of psychological, medical, and educational databases were conducted through October 2017. Eligible peer-reviewed studies evaluated attentional bias in opioid users, used a task to evaluate attentional bias that included active response to study stimuli, calculated attention bias by comparing response to drug and neutral stimuli, and could isolate attentional bias specific to opioid versus neutral stimuli from bias to other salient stimuli.

CONCLUSIONS

The results of our systematic review and meta-analysis suggest that individuals with OUD exhibit robust attentional bias to opioid cues, even when engaged in MAT. Interventions that reduce attentional bias may be a useful adjunct to MAT.

Prescription opioid misusing chronic pain patients exhibit dysregulated context-dependent associations: Investigating associative learning in addiction with the cue-primed reactivity task

BACKGROUND

Associative learning undergirds the development of addiction, such that drug-related cues serve as conditioned stimuli to elicit drug-seeking responses. Plausibly, among opioid misusing chronic pain patients, pain-related information may serve as a conditioned stimulus to magnify opioid cue-elicited autonomic and craving responses through a process of second-order conditioning.

METHODS

We utilized a novel psychophysiological probe of pain-opioid conditioned associations, the Cue-Primed Reactivity (CPR) task. In this task, participants were presented with images as primes (200 ms) and cues (6000 ms) in pairs organized in four task blocks: "control-opioid," "pain-opioid," "control-pain," and "opioid-pain." Opioid-treated chronic pain patients (N = 30) recruited from an Army base in the Western United States were classified as opioid misusers (n = 17) or non-misusers (n = 13) via a validated cutpoint on the Prescription Drug Use Questionnaire (PDUQ; Compton et al., 2008). Opioid misuse status was examined as a predictor of HRV, craving, and mood responses on the CPR task.

RESULTS

HRV increased to a greater extent during the pain-opioid block compared to the control-opioid block for non-misusers compared to misusers (p = .003, η²_partial = 0.27). In contrast, craving increased to a greater extent from baseline to the pain-opioid block for misusers than for non-misusers (p = .03, η²_partial = .16).

CONCLUSIONS

Findings suggest that opioid-treated chronic pain patients exhibit Pavlovian conditioned responses to opioid cues strengthened by an associative learning process of second-order conditioning when primed by pain-related images. This pain-opioid contingency appears to become disrupted among individuals who engage in opioid misuse, such that opioid-related stimuli elicit motivational responses irrespective of pain-related contextual stimuli.

Enhancing Natural Reward Responsiveness Among Opioid Users Predicts Chronic Pain Relief: EEG Analyses From a Trial of Mindfulness-Oriented Recovery Enhancement

OBJECTIVE

Although opioid-treated chronic pain patients evidence blunted responsiveness to natural rewards, focusing on naturally rewarding stimuli can produce analgesia in these patients. A prior randomized controlled trial (RCT) demonstrated that a social work intervention-Mindfulness-Oriented Recovery Enhancement (MORE)-enhanced natural reward processing as indicated by event-related brain potentials (ERPs). The aim of the present study was to perform a secondary data analysis on ERPs collected in this RCT to explore whether improvements in electrocortical response to natural reward predicted pain relief.

METHOD

The sample for this secondary analysis included opioid-treated chronic pain patients with complete ERP data (N = 29). Participants were randomized to 8 weeks of MORE or a support group control condition, and ERPs to images representing naturally rewarding stimuli were measured before and after 8 weeks of treatment. We explored associations between changes in brain reward response, chronic pain symptoms, and pain coping.

RESULTS

Increases in ERP reward response were significantly associated with decreased pain severity from pretreatment to posttreatment (β = -.48, p = .007) and improvements in pain catastrophizing (β = -.36, p = .05) and diverting attention as a means of pain coping (β = .38, p = .043). Increased ERP reward response predicted decreased pain interference by 3-month follow-up (β = -.37, p = .048).

CONCLUSIONS

Chronic pain may be alleviated by enhancing brain response to natural rewards.

Mindfulness is Associated With Increased Hedonic Capacity Among Chronic Pain Patients Receiving Extended Opioid Pharmacotherapy

OBJECTIVES

Chronic pain and long-term opioid use may lead to a persistent deficit in hedonic capacity, characterized by increased sensitivity to aversive states and insensitivity to natural rewards. Dispositional mindfulness has been linked with improved emotion regulation and pain coping. The aim of the current study was to examine associations between dispositional mindfulness, hedonic capacity, and pain-related interference in an opioid-using chronic pain sample.

METHODS

Data were obtained from a sample of 115 chronic pain patients on long-term opioid therapy (68% females, M age=48.3, SD=13.6) who completed the Five Facet Mindfulness Questionnaire (FFMQ), the Snaith-Hamilton Anhedonia and Pleasure Scale (SHAPS), the Brief Pain Inventory, and a psychiatric assessment of major depression. Bivariate correlations, hierarchical multiple regression, and path analysis were used to determine whether dispositional mindfulness scores (FFMQ) predicted variance in hedonic capacity (SHAPS), and whether hedonic capacity mediated the association between mindfulness and pain interference.

RESULTS

We observed a significant positive correlation between dispositional mindfulness and hedonic capacity scores (r=0.33, P<0.001). Hierarchical regression indicated that after controlling for pain interference and major depressive disorder diagnosis, dispositional mindfulness explained a significant portion of variance in hedonic capacity (β=0.30, P<0.01). The association between dispositional mindfulness and pain interference was mediated by hedonic capacity (b=-0.011, SE=0.005; 95% CI, -0.004 to -0.024, full model R=0.39).

DISCUSSION

Findings indicate that dispositional mindfulness was associated with hedonic capacity among this chronic pain sample. In light of this association, it is plausible that interventions that increase mindfulness may reduce pain-related impairment among opioid-using patients by enhancing hedonic capacity.

Deficits in autonomic indices of emotion regulation and reward processing associated with prescription opioid use and misuse

RATIONALE

Prescription opioid misuse and high-dose opioid use may result in allostatic dysregulation of hedonic brain circuitry, leading to reduced emotion regulation capacity. In particular, opioid misuse may blunt the ability to experience and upregulate positive affect from natural rewards.

OBJECTIVES

The purpose of this study was to examine associations between opioid use/misuse and autonomic indices of emotion regulation capability in a sample of chronic pain patients receiving prescription opioid pharmacotherapy.

METHODS

Chronic pain patients taking long-term opioid analgesics (N = 40) completed an emotion regulation task while heart rate variability (HRV) was recorded, and also completed self-report measures of opioid misuse, craving, pain severity, and emotional distress. Based on a validated cut-point on the Current Opioid Misuse Measure, participants were grouped as opioid misusers or non-misusers. Opioid misuse status and morphine equivalent daily dose (MEDD) were examined as predictors of HRV and self-reports of emotion regulation.

RESULTS

Opioid misusers exhibited significantly less HRV during positive and negative emotion regulation, and significantly less positive effect, than non-misusers, after controlling for confounders including pain severity and emotional distress. MEDD was inversely associated with positive emotion regulation efficacy.

CONCLUSION

Findings implicate the presence of reward processing deficits among chronic pain patients with opioid-misusing behaviors, and opioid dosage was associated with deficient emotion regulation, suggesting the presence of compromised top-down cognitive control over bottom-up hedonic processes. Emotion regulation among opioid misusers may represent an important treatment target.

Suicidal ideation is associated with individual differences in prescription opioid craving and cue-reactivity among chronic pain patients

Given that chronic pain patients experience significant rates of suicidal ideation and suicide attempts, access to prescription opioids compounds the risk of death by suicide. These patients may experience heightened opioid craving and exhibit increased cue-reactivity to stimuli associated with past opioid use when suicidal ideation produces negative affective states. Because both opioids and suicidal behavior are used to alleviate emotional and physical pain through a process of negative reinforcement, elucidating factors that mediate this association may yield insight into suicide risk among chronic pain patients. This study examined the relationship between suicidal ideation and opioid craving and cue-reactivity, and tested opioid self-medication as a mediator of associations between those factors after controlling for the impact of pain severity. A sample of 115 chronic pain patients provided demographic and clinical information on the Obsessive Compulsive Drug Use Scale, the Current Opioid Misuse Measure, and the Brief Pain Inventory before completing an opioid dot probe task in which heart rate variability was recorded. As hypothesized, suicidal ideation was positively correlated with subjective opioid craving and physiological cue-reactivity. Self-medication significantly mediated the association between suicidal ideation, craving, and cue-reactivity. As opioids relieve the emotional pain linked with suicidal thoughts, chronic pain patients with higher levels of suicidal ideation may experience more intense opioid craving and exhibit heightened physiological cue-reactivity when compared to patients with low levels of suicidal ideation.