Enhanced choice for viewing cocaine pictures in cocaine addiction

Tobacco Images Choice and Its Association with Craving and Dependence in Cigarette Smokers

Introduction

Increased salience of drug-related cues over non-drug reinforcers can drive drug use and contribute to tobacco use disorder (TUD). An important scientific and clinical goal is to effectively measure this elevated drug-seeking behavior in TUD. However, most TUD assessments rely on self-reported cravings and cigarette consumption, not providing an objective measure of the impact of drug-cues on biasing behavior towards drugs. The probabilistic image choice (PIC) task investigates the choice of viewing drug-related pictures as compared to other salient pictures (e.g., pleasant and unpleasant). This study aimed to develop and validate the PIC task for TUD and evaluate the associations between behavioral choice and tobacco craving, daily cigarette consumption, quit attempts and motivation to quit, and nicotine dependence (the Fagerström score).

Methods

We recruited 468 smokers and 121 nonsmokers using the Prolific online platform. Participants performed the PIC task twice (at a one-month interval) and completed other measures relevant to TUD.

Results

compared to nonsmokers, tobacco smokers selected to view significantly more tobacco images and less pleasant (non-drug reinforcer) images, a profile that remained stable at retest. Individual differences in choice of tobacco as compared to pleasant images on the PIC task were associated with craving but not with the other tobacco dependence measures, suggesting that the task may serve as a behavioral proxy measure of drug "wanting" rather than of cumulative nicotine exposure or physical dependence.

Conclusions

these results suggest that the PIC task can be a valuable tool for objectively assessing craving-associated tobacco seeking in TUD.

Neurophysiological error processing and addiction self-awareness correlates of reduced insight in cannabis use disorder

BACKGROUND AND AIMS

Cannabis use disorder (CUD) prevalence has increased, while perceived risks of cannabis use and CUD treatment need have decreased. Chronic cannabis use may also impair the neural and behavioral mechanisms of insight, further hampering treatment-seeking. This study aimed to measure whether CUD is characterized by reduced self-monitoring in drug-related contexts (objectively-assessed insight), subserved by functional neural abnormalities in error-processing and manifested clinically as decreased awareness of the need to change.

DESIGN

Case-control laboratory study was used.

SETTING

University setting was in Alabama, USA.

PARTICIPANTS

There were 42 CUD participants and 47 age-, sex-, and nicotine use-matched controls.

MEASUREMENTS

Participants completed a probabilistic choice task, adapted for the first time for CUD, in which they selected pleasant, unpleasant, neutral, and cannabis-related images according to their preference. Reduced versus accurate insight was operationalized as the correspondence between self-reported and actual most chosen image type. Neurophysiological error-processing during an inhibitory control task was recorded using electroencephalography. Participants with CUD completed measures of cannabis problem recognition and motivation to change.

FINDINGS

Compared with controls, the CUD group made significantly more cannabis selections on the choice task (mean difference [MD] = 8.11, 95% confidence interval [CI] [4.88 11.35], p < 0.001) and had significantly reduced insight into cannabis choice (odds ratio [OR] = 9.69, 95% CI [1.06 88.65], p = 0.04). CUD participants with reduced insight on the choice task had significantly decreased neurophysiological reactivity to errors on the inhibitory control task (error-related negativity) compared with CUD participants with accurate insight (MD = 2.64 μV, 95% CI [0.74 μV 4.54 μV], p = 0.008) and controls (MD = 4.05 μV, 95% CI [1.29 μV 6.80 μV], p = 0.005). Compared with CUD participants with accurate insight on the choice task, CUD participants with reduced insight reported significantly less agreement that they had a cannabis problem (MD = -5.06, 95% CI [-8.49-1.62], p = 0.003).

CONCLUSIONS

People with CUD who show reduced insight on a drug-related choice task may also have decreased early neural error-processing and less cannabis problem recognition.

Assessing cocaine motivational value: Comparison of brain reactivity bias toward cocaine cues and cocaine demand

The behavioral economic measure drug demand and the neural measure late positive potential (LPP) are two measures of motivational value that have been associated with drug relapse risk and treatment outcomes. Despite having overlapping themes, no studies have directly compared drug demand and LPP. Participants (N = 59) included treatment-seeking individuals with cocaine use disorder that had completed both a baseline cocaine demand task and an electroencephalogram (EEG) picture-viewing task of drug-related and pleasant picture cues. Associations between the LPP difference score amplitude (drug-pleasant) and five demand indices (Q₀, essential value [EV], Omax, Pmax, and breakpoint [BP]) were evaluated via Bayesian generalized linear modeling. Positive associations (posterior probabilities ≥ 75%) were found between LPP amplitude and four demand indices (Q₀, EV, Omax, BP). These results suggest that individuals who attach greater relevance to cocaine cues also exhibit greater valuation of cocaine reward. Implications for incorporating methodology from behavioral science and brain imaging are discussed. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Candidate biomarkers in psychiatric disorders: state of the field

The field of psychiatry is hampered by a lack of robust, reliable and valid biomarkers that can aid in objectively diagnosing patients and providing individualized treatment recommendations. Here we review and critically evaluate the evidence for the most promising biomarkers in the psychiatric neuroscience literature for autism spectrum disorder, schizophrenia, anxiety disorders and post-traumatic stress disorder, major depression and bipolar disorder, and substance use disorders. Candidate biomarkers reviewed include various neuroimaging, genetic, molecular and peripheral assays, for the purposes of determining susceptibility or presence of illness, and predicting treatment response or safety. This review highlights a critical gap in the biomarker validation process. An enormous societal investment over the past 50 years has identified numerous candidate biomarkers. However, to date, the overwhelming majority of these measures have not been proven sufficiently reliable, valid and useful to be adopted clinically. It is time to consider whether strategic investments might break this impasse, focusing on a limited number of promising candidates to advance through a process of definitive testing for a specific indication. Some promising candidates for definitive testing include the N170 signal, an event-related brain potential measured using electroencephalography, for subgroup identification within autism spectrum disorder; striatal resting-state functional magnetic resonance imaging (fMRI) measures, such as the striatal connectivity index (SCI) and the functional striatal abnormalities (FSA) index, for prediction of treatment response in schizophrenia; error-related negativity (ERN), an electrophysiological index, for prediction of first onset of generalized anxiety disorder, and resting-state and structural brain connectomic measures for prediction of treatment response in social anxiety disorder. Alternate forms of classification may be useful for conceptualizing and testing potential biomarkers. Collaborative efforts allowing the inclusion of biosystems beyond genetics and neuroimaging are needed, and online remote acquisition of selected measures in a naturalistic setting using mobile health tools may significantly advance the field. Setting specific benchmarks for well-defined target application, along with development of appropriate funding and partnership mechanisms, would also be crucial. Finally, it should never be forgotten that, for a biomarker to be actionable, it will need to be clinically predictive at the individual level and viable in clinical settings.

Effect of environmental enrichment on relapse rates in patients with severe alcohol use disorder: protocol for a randomised controlled trial

INTRODUCTION

Alcohol use disorder (AUD) ranks among the most prevalent psychiatric disorders worldwide. Despite current treatments, more than half of patients relapse within weeks after treatment. In animal models, exposure to environmental enrichment (EE) has been shown to be a promising approach to reduce relapse. However, controlled, multimodal EE is difficult to transpose to humans. To address this gap, this study aims at assessing the effectiveness of exposure to a newly designed EE protocol during AUD treatment in reducing relapse to alcohol use. Our EE will allow an enhancement of the standard intervention, and will combine several promising enrichment factors identified in the literature-physical activity, cognitive stimulation, mindfulness and virtual reality (VR).

METHODS AND ANALYSIS

A randomised controlled trial involving 135 participants receiving treatment for severe AUD will be conducted. Patients will be randomised to an intervention enhancement group or a control group. The enhanced intervention will consist of six 40-min sessions of EE spread over 9 days. During the first 20 min of these sessions, patients will practise mindfulness in multisensory VR, in virtual environments designed to practise mindfulness and use it to regulate craving induced by virtual cues or stress. Then, participants will practise indoor cycling combined with cognitive training exercises. The control group will undergo standard management for AUD. The primary outcome is relapse assessed at 2 weeks after treatment, using a questionnaire and biological indicators. Relapse will be defined as drinking at least five drinks per occasion or drinking at least five times a week. It is predicted that the group receiving the EE intervention will have a lower relapse rate than the control group. The secondary outcomes are relapse at 1 month and 3 months after treatment, craving and drug-seeking behaviour, mindfulness skills acquisition and the effect of the intervention enhancement on the perceived richness of the daily environment, assessed by questionnaires and neuropsychological tasks.

ETHICS AND DISSEMINATION

All participants have to give written informed consent to the investigator. This study is approved by the Ethics Committee Nord Ouest IV of Lille (reference number 2022-A01156-37). Results will be disseminated through presentations, peer-reviewed journals and seminar conferences. All information on ethical considerations and open science practices can be accessed at https://osf.io/b57uj/ TRIAL REGISTRATION NUMBER: NCT05577741.

An fMRI marker of drug and food craving

Craving is a core characteristic of drug addiction and eating disorders. A new study identifies an fMRI-based neural signature of craving that is common to both food and drugs, predicts self-reported craving, distinguishes drug users from non-users, and tracks the efficacy of a cognitive therapy technique to reduce craving.

Altered prefrontal signaling during inhibitory control in a salient drug context in cocaine use disorder

INTRODUCTION

Drug addiction is characterized by impaired response inhibition and salience attribution (iRISA), where the salience of drug cues is postulated to overpower that of other reinforcers with a concomitant decrease in self-control. However, the neural underpinnings of the interaction between the salience of drug cues and inhibitory control in drug addiction remain unclear.

METHODS

We developed a novel stop-signal functional magnetic resonance imaging task where the stop-signal reaction time (SSRT-a classical inhibitory control measure) was tested under different salience conditions (modulated by drug, food, threat, or neutral words) in individuals with cocaine use disorder (CUD; n = 26) versus demographically matched healthy control participants (n = 26).

RESULTS

Despite similarities in drug cue-related SSRT and valence and arousal word ratings between groups, dorsolateral prefrontal cortex (dlPFC) activity was diminished during the successful inhibition of drug versus food cues in CUD and was correlated with lower frequency of recent use, lower craving, and longer abstinence (Z > 3.1, P < 0.05 corrected).

DISCUSSION

Results suggest altered involvement of cognitive control regions (e.g. dlPFC) during inhibitory control under a drug context, relative to an alternative reinforcer, in CUD. Supporting the iRISA model, these results elucidate the direct impact of drug-related cue reactivity on the neural signature of inhibitory control in drug addiction.

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.

The neurobiology of drug addiction: cross-species insights into the dysfunction and recovery of the prefrontal cortex

A growing preclinical and clinical body of work on the effects of chronic drug use and drug addiction has extended the scope of inquiry from the putative reward-related subcortical mechanisms to higher-order executive functions as regulated by the prefrontal cortex. Here we review the neuroimaging evidence in humans and non-human primates to demonstrate the involvement of the prefrontal cortex in emotional, cognitive, and behavioral alterations in drug addiction, with particular attention to the impaired response inhibition and salience attribution (iRISA) framework. In support of iRISA, functional and structural neuroimaging studies document a role for the prefrontal cortex in assigning excessive salience to drug over non-drug-related processes with concomitant lapses in self-control, and deficits in reward-related decision-making and insight into illness. Importantly, converging insights from human and non-human primate studies suggest a causal relationship between drug addiction and prefrontal insult, indicating that chronic drug use causes the prefrontal cortex damage that underlies iRISA while changes with abstinence and recovery with treatment suggest plasticity of these same brain regions and functions. We further dissect the overlapping and distinct characteristics of drug classes, potential biomarkers that inform vulnerability and resilience, and advancements in cutting-edge psychological and neuromodulatory treatment strategies, providing a comprehensive landscape of the human and non-human primate drug addiction literature as it relates to the prefrontal cortex.

Posttraumatic stress symptom clusters differentially predict late positive potential to cocaine imagery cues in trauma-exposed adults with cocaine use disorder

BACKGROUND

While studies have investigated the effects of posttraumatic stress disorder (PTSD) symptoms on substance use, information on these associations in the context of drug cue reactivity is lacking, which can provide meaningful information about risk for relapse. The current study assessed the associations between PTSD symptom clusters and reactivity to cues in trauma-exposed adults with cocaine use disorder.

METHODS

We recorded electroencephalogram on 52 trauma-exposed participants (M_age = 51.3; SD = 7.0; 15.4 % women) diagnosed with cocaine use disorder while they viewed pleasant (i.e., erotic, romantic, sweet foods), unpleasant (i.e., mutilations, violence, accidents), neutral, and cocaine-related images. Reactivity was measured with the late positive potential (LPP), an indicator of motivational relevance. It was hypothesized that individuals with greater PTSD avoidance and negative alterations in cognition and mood (NACM) symptoms, as determined by the PTSD Checklist for DSM-5 (PCL-5), would have higher LPPs to cocaine-related images, indicating greater cue reactivity.

RESULTS

Linear mixed modeling indicated that higher NACM symptomatology was associated with higher LPPs to cocaine cues and higher arousal/reactivity was associated with lower LPPs to cocaine cues.

CONCLUSIONS

These results highlight the potential clinical utility of the LPP in assessing drug cue reactivity in trauma-exposed adults with substance use disorder.

Attention bias modification in drug addiction: Enhancing control of subsequent habits

A relapse in addiction is often precipitated by heightened attention bias to drug-related cues, underpinned by a subcortically mediated transition to habitual/automatized responding and reduced prefrontal control. Modification of such automatized attention bias is a fundamental, albeit elusive, target for relapse reduction. Here, on a trial-by-trial basis, we used electroencephalography and eye tracking with a task that assessed, in this order, drug cue reactivity, its instructed self-regulation via reappraisal, and the immediate aftereffects on spontaneous (i.e., not instructed and automatized) attention bias. The results show that cognitive reappraisal, a facet of prefrontal control, decreased spontaneous attention bias to drug-related cues in cocaine-addicted individuals, more so in those with less frequent recent use. The results point to the mechanisms underlying the disruption of automatized maladaptive drug-related attention bias in cocaine addiction. These results pave the way for future studies to examine the role of such habit disruption in reducing compulsive drug seeking outside the controlled laboratory environment, with the ultimate goal of developing a readily deployable cognitive-behavioral and personalized intervention for drug addiction.

Development and Feasibility Study of an Addiction-Focused Phenotyping Assessment Battery

BACKGROUND AND OBJECTIVES

Current methods of classifying individuals with substance use disorder (SUD) result in vast heterogeneity among persons within a given diagnosis. These approaches, while clinically allowing for distinctions between patient groups, are less than ideal when attempting to recruit a neurobehaviorally defined subset of subjects into clinical trials. To address this gap, alternative strategies have been proposed, including behavioral phenotyping. The NIDA Phenotyping Assessment Battery (PhAB) is a modular package of assessments and neurocognitive tasks that was developed for use in clinical trials. The goal of the present study is to assess the feasibility of the NIDA PhAB with regard to ease of administration and time burden.

METHODS

Healthy controls, persons with cocaine use disorder (CocUD), opioid use disorder (OUD), cannabis use disorder (CanUD), and combined opioid and cocaine use disorder (OCUD) were recruited from various sources (N = 595). Participants completed screening and one to three assessment visits. Time to complete the measures was recorded and a satisfaction interview was administered.

RESULTS

Of the participants enrolled, 381 were deemed eligible. The majority of eligible participants (83%) completed all assessments. The average completion time was 3 hours. High participant satisfaction ratings were noted, with over 90% of participants endorsing a willingness to participate in a similar study and recommend the study to others. CONCLUSION AND SCIENTIFIC SIGNIFICANCE: These findings corroborate the ease with which the PhAB may be easily incorporated into a study assessment visit without undue participant burden. The PhAB is an efficient method for behavioral phenotyping in addiction clinical trials. (Am J Addict 2021;00:00-00).

Insight in substance use disorder: A systematic review of the literature

Insight refers to a person's understanding of themselves and the world around them. Recent literature has explored people's insight into their substance use disorder (SUD) and how this is linked to treatment adherence, abstinence rates, and comorbid mental health symptoms. The aim of this systematic review was to synthesise and critically examine the existing literature on insight in SUD. Five academic databases (Medline, PsychINFO, SCOPUS, CINAHL, Web of Science) were searched for key terms related to insight and substance use. Included studies were on humans aged 18 years or over with SUD that examined the relationship between substance use and insight using a quantifiable measure of insight. Of 10,067 identified papers, 20 met the inclusion criteria, employing 13 different measures of insight. The most commonly used measure was the Hanil Alcohol Insight Scale (HAIS) which was the only measure designed for a substance use population and was specific to alcohol use. Based on a pooled sample from five studies (n = 585), 57% of participants had poor insight, 36% had fair insight, and 7% had good insight on the HAIS. Better insight was generally related to negative consequences from substance use, better treatment adherence and maintaining abstinence. Insight appears to be an important factor to consider within SUD. Exploring the most appropriate way to measure insight and assess its role in SUD has implications for intervention design, and engaging and maintaining people with SUD in treatment.

Relative expected value of drugs versus competing rewards underpins vulnerability to and recovery from addiction

Behavioural economic theories of addiction contend that greater expected value of drug relative to alternative non-drug rewards is the core mechanism underpinning vulnerability to and recovery from addiction. To evaluate this claim, we exhaustively review studies with human drug users that have measured concurrent choice between drugs vs. alternative rewards, and explored individual differences. These studies show that drug choice can be modulated by drug cues, drug devaluation, imposition of costs/punishment and negative mood induction. Regarding individual differences, dependence severity was reliably associated with overall drug preference, and self-reported drug use to cope with negative affect was reliably associated with greater sensitivity to mood induced increases in drug choice. By contrast, there were no reliable individual differences in sensitivity to the effect of drug cues, drug devaluation or punishment on drug choice. These findings provide insight into the mechanisms that underpin vulnerability to dependence: vulnerability is conferred by greater relative value ascribed to drugs, and relative drug value is further augmented by negative affective states in those who report drug use coping motives. However, dependence does not appear to be characterised by abnormal cue-reactivity, habit learning or compulsion. We then briefly review emerging literature which demonstrates that therapeutic interventions and recovery from addiction might be attributed to changes in the expected relative value of drug versus alternative rewards. Finally, we outline a speculative computational account of the distortions in decision-making that precede action selection in addiction, and we explain how this account provides a blueprint for future research on the determinants of drug choice, and mechanisms of treatment and recovery from addiction. We conclude that a unified economic decision-making account of addiction has great promise in reconciling diverse addiction theories, and neuropsychological evaluation of the underlying decision mechanisms is a fruitful area for future research and treatment.

Contribution of alcohol- and cigarette-related cues to concurrent reinforcer choice in humans

Drug-related cues have been extensively studied for their contributions to decision-making processes involving drug consumption. Less studied is how drug-related stimuli may impact decisions involving outcomes not directly related to substance use. Studies using concurrent choice tasks have demonstrated that cocaine and cannabis cues result in robust and selective biases for monetary reinforcers contiguous with those cues. The purpose of this study was to provide a conceptual replication of these findings with alcohol and cigarettes. Participants recruited using crowdsourcing completed a cued concurrent choice task involving presentation of two cues (one drug and one neutral) followed by concurrent monetary offers below each image. Alcohol (Experiment 1; N = 103) and cigarette (Experiment 2; N = 256) visual cues were evaluated. Participants with hazardous alcohol use and current cigarette use showed greater-than-indifference selection for the alcohol- (p = .004) and cigarette-cued (p = .02) monetary choices, respectively. Qualitative responses indicated that the most popular rationale for responding was "image quality" despite images having no explicit impact on the reinforcer received. Low alcohol use (p = .03) and non-cigarette using controls (p < .001) showed an avoidance bias with lower-than-indifference selection for drug-cued choices. These findings replicate and extend observations that spatially contiguous drug-related cues can bias decisions involving concurrently presented non-drug reinforcers.

Addiction is driven by excessive goal-directed drug choice under negative affect: translational critique of habit and compulsion theory

Drug addiction may be a goal-directed choice driven by excessive drug value in negative affective states, a habit driven by strong stimulus-response associations, or a compulsion driven by insensitivity to costs imposed on drug seeking. Laboratory animal and human evidence for these three theories is evaluated. Excessive goal theory is supported by dependence severity being associated with greater drug choice/economic demand. Drug choice is demonstrably goal-directed (driven by the expected value of the drug) and can be augmented by stress/negative mood induction and withdrawal-effects amplified in those with psychiatric symptoms and drug use coping motives. Furthermore, psychiatric symptoms confer risk of dependence, and coping motives mediate this risk. Habit theory of addiction has weaker support. Habitual behaviour seen in drug-exposed animals often does not occur in complex decision scenarios, or where responding is rewarded, so habit is unlikely to explain most human addictive behaviour where these conditions apply. Furthermore, most human studies have not found greater propensity to habitual behaviour in drug users or as a function of dependence severity, and the minority that have can be explained by task disengagement producing impaired explicit contingency knowledge. Compulsion theory of addiction also has weak support. The persistence of punished drug seeking in animals is better explained by greater drug value (evinced by the association with economic demand) than by insensitivity to costs. Furthermore, human studies have provided weak evidence that propensity to discount cost imposed on drug seeking is associated with dependence severity. These data suggest that human addiction is primarily driven by excessive goal-directed drug choice under negative affect, and less by habit or compulsion. Addiction is pathological because negative states powerfully increase expected drug value acutely outweighing abstinence goals.

Self-awareness of problematic drug use: Preliminary validation of a new fMRI task to assess underlying neurocircuitry

BACKGROUND

Multiple psychopathologies feature impaired clinical insight. Emerging evidence suggests that insight problems may similarly characterize addiction, perhaps due to aberrant functioning of self-referential brain circuitry, including the rostral anterior cingulate and ventromedial prefrontal cortices (rACC/vmPFC). We developed a new fMRI task to probe whether rACC/vmPFC abnormalities in cocaine use disorder (CUD) constitute neural correlates of readiness to change, one facet of insight.

METHODS

Eighteen individuals with current CUD and 15 healthy controls responded about their own need to change their drug use and eating behavior (control condition) and the need for a named acquaintance to do the same (two additional control conditions). Measures of simulated drug-choice behavior, addiction severity, and neuropsychological function were collected outside the scanner.

RESULTS

CUD participants perceived a greater need for behavior change than controls (as expected, given their diagnosis), but fell short of "agreeing" to a need for change; in CUD, lower perceived need correlated with higher simulated drug-choice behavior, a proxy measure of drug-seeking. During drug-related insight judgments, CUD participants had higher activation than controls in an anatomically-defined region of interest (ROI) in the medial orbitofrontal cortex, part of the rACC/vmPFC. Although not showing group differences, activation in an anatomically-defined ACC ROI correlated with insight-related task behavior (in all participants) and memory performance (in CUD).

CONCLUSIONS

As a group, individuals with current CUD appear to show mild insight problems and rACC/vmPFC abnormalities vis-à-vis readiness to change behavior. With replication and extension of these results, insight-related circuitry may emerge as a novel therapeutic target.

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.

A concurrent pictorial drug choice task marks multiple risk factors in treatment-engaged smokers and drinkers

Concurrent choice tasks, where participants choose between a drug versus natural reward, predict dependence vulnerability in animals and humans. However, the sensitivity of concurrent choice tasks to multiple risk factors in treatment-engaged drug users has not been comprehensively tested. In experiment 1, 33 recently hospitalized smokers who were engaged with the smoking cessation service made forced choices between enlarging pictures of people smoking versus not smoking. In experiment 2, 48 drinkers who were engaged in an outpatient alcohol treatment service made forced choices between enlarging pictures of alcohol versus food. In these experiments, percent drug picture choice was significantly associated with dependence severity, craving, self-reported reasons for drug use (negative coping and cued craving), depression, anxiety, withdrawal intolerance, drug use frequency prior to treatment, and current abstinence status (coefficients ranged from r=0.39 to 0.66). The concurrent pictorial drug choice task is sensitive to multiple risk factors in clinical, treatment-engaged drug users, and may be used to identify individuals requiring more support, to test experimental treatment manipulations, and to translate to animal concurrent self-administration procedures.

Strengths, weaknesses, opportunities and threats (SWOT) analysis of reinitiation into methamphetamine abusers: qualitative findings from an exploration of methamphetamine abusers in Shanghai, China

Background

Despite high relapse rate among methamphetamine (MA) abusers, there still have been little empirical data to date detecting the risk factors related to craving and relapse from the perspective of MA abusers. Therefore, the aim of this study was to use qualitative research methods exploring the strengths, weaknesses, opportunities and threat factors that could facilitate or impede individuals' abstinence in a real-life context from the perspectives of MA abusers.

Aim

To use qualitative research methods exploring the strengths, weaknesses, opportunities and threat factors relating to individuals' abstinence in a real-life context.

Method

Semistructured interviews were conducted with 32 MA abusers recruited in Shanghai guided by open-ended questions on narrating the real-life catalysts and inhibitors related to craving, initiation, relapse and abstinence. All data were transcribed verbatim and analysed using a strengths, weaknesses, opportunities and threats (SWOT) analysis.

Results

The results of the SWOT analysis revealed that contextual factors including peer influence, prevalence and availability of MA, familiar venue of MA use, discrimination, sexual behaviours, alcohol, emotional states and their attitudes towards smoking MA were important factors that contribute to reinitiation and relapse. Surveillance systems, antidrug social workers, vocational skills trainings, moving to another city and family responsibility might serve as counter measures targeting those mentioned weaknesses and threats above.

Conclusion

This SWOT analysis highlights the complex nature of relapse. Comprehensive interventions strengthening coping skills such as virtual reality techniques are desperately needed to facilitate individuals' sustained abstinence.

Contribution of cannabis-related cues to concurrent reinforcer choice in humans

BACKGROUND

Drug-related cues play a critical role in the development and persistence of substance use disorder. Few human laboratory studies have evaluated how these cues contribute to decisions between concurrently presented reinforcers, and none have examined the specific role of cannabis cues. This study evaluated the contribution of cannabis-related cues to concurrent monetary reinforcer choice in humans.

METHODS

Participants with a cannabis use history (i.e., use in the past two weeks and 50 or more lifetime uses; n = 71) and controls without this history (i.e., 5 or less lifetime uses; n = 79) were recruited using Amazon Mechanical Turk. A cued concurrent choice task was used in which cannabis trials presented two cues (one cannabis and one neutral) side-by-side followed by concurrent monetary offers below each image. The primary dependent measure was choice for cannabis-cued monetary reinforcers on equal value trials. Secondary analyses evaluated individual difference variables related to choice bias.

RESULTS

Participants in the cannabis group showed a significant bias for cannabis-cued choices (mean 76.0%) whereas participants in the control group showed a significant bias against cannabis-cued choices (mean 30.3%). Reaction times on cannabis trials were faster than neutral filler trials and did not differ by group. Cannabis-cued choice was significantly associated with more frequent cannabis use (r = .44), higher cannabis demand intensity (r = .28), and lower cannabis elasticity (r = -.30).

CONCLUSIONS

These findings suggest that cannabis-related cues can influence reinforcer choice and potentially promote disadvantageous decision-making related to non-drug reinforcers.

Knowledge about the predictive value of reward conditioned stimuli modulates their interference with cognitive processes

Stimuli conditioned with a substance can generate drug-approach behaviors due to their acquired motivational properties. According to implicit theories of addiction, these stimuli can decrease cognitive control automatically. The present study (n = 49) examined whether reward-associated stimuli can interfere with cognitive processes in the absence of knowledge about stimulus–outcome contingencies. Conditioned stimuli (CS) were paired with high-reward (HR) or low-reward (LR) probabilities of monetary reward using a Pavlovian learning task. Participants were categorized as Aware or Unaware of contingencies using a Bayesian analysis. CS were then used as task-irrelevant distractors in modified flanker and N-back tasks. Results show HR CS can generate increased interference in the flanker task for participants Unaware of contingencies, contributing further evidence for the existence of implicit Pavlovian conditioning. For the N-back task, working memory performance was affected by HR CS, albeit only for Aware participants. These results suggest that CS can interfere implicitly with cognitive processes in a similar way to drug-related stimuli. Such an effect could occur in a stimulus-driven fashion, devoid of top-down goal-directedness. These findings have implications for the conceptualization and study of implicit processes in addiction and highlights the necessity to reconsider the measurement of such phenomena.

No effect of attentional bias modification training in methamphetamine users receiving residential treatment

RATIONALE

Attentional bias toward drug-related stimuli is a feature of drug addiction that is linked to craving and drug-seeking behavior.

OBJECTIVES/METHOD

An attentional bias modification (ABM) program was tested in 42 methamphetamine-dependent clients (DSM-IV criteria) receiving residential treatment for their drug use. Participants were randomly assigned to one of two groups (N = 21 each), receiving 12 sessions of either computerized ABM training (designed to train attention away from methamphetamine stimuli 100% of the time) or an attentional control condition (designed to train attention away from methamphetamine stimuli 50% of the time). Outcome measures included attentional bias to methamphetamine-related stimuli on a probe detection task, self-reported craving, and preferences to view methamphetamine-related images on a Simulated Drug Choice Task. A subset of participants (N = 17) also underwent fMRI in a cue-induced craving paradigm.

RESULTS

Poor split-half reliability was observed for the probe detection task. Using this task, attentional bias toward methamphetamine-related stimuli was greater after training than at baseline, irrespective of group (p = 0.037). Spontaneous and cue-induced methamphetamine craving diminished with time (ps < 0.01), but ABM training did not influence these effects (group by time interactions, ps > 0.05). ABM training did not influence selection of methamphetamine-related pictures in the Simulated Drug Choice task (p > 0.05). In the fMRI assessment, cue-induced activation in the ventromedial prefrontal cortex was reduced over time, without an effect of ABM training.

CONCLUSIONS

ABM training did not improve several clinically relevant variables in treatment-seeking methamphetamine users. Additional research is needed to improve the measurement of attentional bias.

Neural mechanisms of extinguishing drug and pleasant cue associations in human addiction: role of the VMPFC

The neurobiological mechanisms that underlie the resistance of drug cue associations to extinction in addiction remain unknown. Fear extinction critically depends on the ventromedial prefrontal cortex (VMPFC). Here, we tested if this same region plays a role in extinction of non-fear, drug and pleasant cue associations. Eighteen chronic cocaine users and 15 matched controls completed three functional MRI scans. Participants first learned to associate an abstract cue (the conditioned stimulus, CS) with a drug-related (CS_D+ ) or pleasant (CS_P+ ) image. Extinction immediately followed where each CS was repeatedly presented without the corresponding image. Participants underwent a second identical session 24 hours later to assess retention of extinction learning. Results showed that like fear extinction, non-fear-based extinction relies on the VMPFC. However, extinction-related changes in the VMPFC differed by cue valence and diagnosis. In controls, VMPFC activation to the CS_D+ (which was unpleasant for participants) gradually increased as in fear extinction, while it decreased to the CS_P+ , consistent with a more general role of the VMPFC in flexible value updating. Supporting a specific role in extinction retention, we further observed a cross-day association between VMPFC activation and skin conductance, a classic index of conditioned responses. Finally, cocaine users showed VMPFC abnormalities for both CSs, which, in the case of the CS_D+ , correlated with craving. These data suggest a global deficit in extinction learning in this group that may hinder extinction-based treatment efforts. More broadly, these data show that the VMPFC, when functionally intact, supports extinction learning in diverse contexts in humans.

Negative Mood Induction Increases Choice of Heroin Versus Food Pictures in Opiate-Dependent Individuals: Correlation With Self-Medication Coping Motives and Subjective Reactivity

Acute growth in negative affect is thought to play a major role in triggering relapse in opiate-dependent individuals. Consistent with this view, three lab studies have demonstrated that negative mood induction increases opiate craving in opiate-dependent individuals. The current study sought to confirm these effects with a behavioral measure of heroin seeking, and test whether the effect is associated with self-reported opiate use to cope with negative affect and subjective reactivity to mood induction. Participants were heroin-dependent individuals engaged with treatment services (n = 47) and control participants (n = 25). Heroin users completed a questionnaire assessing reasons for using heroin: negative affect, social pressure, and cued craving. Baseline heroin choice was measured by preference to enlarge heroin versus food thumbnail pictures in two-alternative forced-choice trials. Negative mood was then induced by depressive statements and music before heroin choice was tested again. Subjective reactivity was indexed by negative and positive mood reported at the pre-induction to post-test timepoints. Heroin users chose heroin images more frequently than controls overall ( p = .001) and showed a negative mood-induced increase in heroin choice compared to control participants (interaction p < .05). Mood-induced heroin choice was associated with self-reported heroin use to cope with negative affect ( p < .05), but not social pressure ( p = .39) or cued craving ( p = .52), and with subjective mood reactivity ( p = .007). These data suggest that acute negative mood is a trigger for heroin seeking in heroin-dependent individuals, and this effect is pronounced in those who report using heroin to cope with negative affect, and those who show greater subjective reactivity to negative triggers. Interventions should seek to target negative coping motives to build resilience to affective triggers for relapse.

Contribution of cocaine-related cues to concurrent monetary choice in humans

RATIONALE

Theoretical accounts highlight the importance of drug-related cues for the development and persistence of drug-taking behavior. Few studies have evaluated the ability of spatially contiguous drug cues to bias decisions between two concurrently presented non-drug reinforcers.

OBJECTIVE

Evaluate the contribution of spatially contiguous cocaine cues to choice between two concurrently presented monetary reinforcers METHODS: Participants with cocaine use disorder completed a cued concurrent choice task. Two cues (one cocaine and one control image) were presented side-by-side followed by concurrent monetary offers below each image. Concurrent choice was measured for cocaine-side advantageous, equal, and disadvantageous concurrent monetary offers. The primary dependent measure was bias for selecting cocaine-cued monetary reinforcers. Three experiments tested selectivity of cocaine-cued bias in individuals with a cocaine use history (Experiment 1), replication when including additional control trials (Experiment 2), and a potential attentional mechanism evaluated using eye-tracking technology (Experiment 3).

RESULTS

Significant and robust cocaine-cued bias at equal monetary value was observed in three experiments (mean percent choice = 65-77%) and higher Drug Abuse Screening Test (DAST) scores were associated with greater cocaine-choice bias. These experiments demonstrated that cocaine-cued bias was (1) selective to individuals with a cocaine use history, (2) specific to trials involving a cocaine cue, and (3) partially associated with attentional bias.

CONCLUSIONS

These experiments provide evidence that drug-related cues can influence choice and potentially promote maladaptive decision making during concurrent choice events. Future research evaluating prospective associations of drug-cued bias with drug-associated behaviors will help reveal the clinical relevance for substance use disorder.

A Newly Designed Mobile-Based Computerized Cognitive Addiction Therapy App for the Improvement of Cognition Impairments and Risk Decision Making in Methamphetamine Use Disorder: Randomized Controlled Trial

Background

Cognitive rehabilitation therapy has been found to improve cognitive deficits and impulse control problems in methamphetamine use disorder (MUD). However, there is limited research regarding this therapy’s feasibility when using mobile-based health technologies in supporting recovery from MUD in China.

Objective

The main aim of this study was to test whether 4 weeks of a newly designed computerized cognitive addiction therapy (CCAT) app can improve cognitive impairments, eliminate drug-related attention bias, and attenuate risk decision-making behaviors in participants with MUD.

Methods

Forty MUD participants were assigned randomly to either the CCAT group (n=20), who received 4 weeks of CCAT plus regular detoxification treatment as usual, or the control group (n=20), who only received the regular detoxification treatment as usual, in drug rehabilitation centers in Shanghai. The CCAT was designed by combine methamphetamine use-related picture stimuli with cognitive training with the aim of improving cognitive function and eliminating drug-related attention bias. The CogState Battery, Delay Discounting Task (DDT), Iowa Gambling Task (IGT), and Balloon Analog Risk Task (BART) were administered face-to-face to all participants before and after CCAT interventions.

Results

Forty male patients were recruited. The mean age was 32.70 (SD 5.27) years in the CCAT group and mean 35.05 (SD 8.02) years in the control group. Compared to the control group, CCAT improved working memory in the CCAT group (P=.01). Group×time interactions were observed among DDT, IGT, and BART tasks, with rates of discounting delayed rewards, IGT, and BART scores (P<.001) being reduced among those who received CCAT, whereas no changes were found in the control group.

Conclusions

The newly designed CCAT can help to improve cognitive impairment and impulsive control in MUD. Further study is needed to understand the underlying brain mechanisms of the cognitive therapy.

Trial Registration

ClinicalTrials.gov NCT03318081; https://clinicaltrials.gov/ct2/show/NCT03318081 (Archived by WebCite at https://clinicaltrials.gov/ct2/show/NCT03318081)

Neural Correlates of Drug-Biased Choice in Currently Using and Abstinent Individuals With Cocaine Use Disorder

BACKGROUND

The choice for drugs over alternative reinforcers is a translational hallmark feature of drug addiction. The neural basis of such drug-biased choice is not well understood, particularly in individuals with protracted drug abstinence who cannot ethically participate in studies that offer drug-using opportunities.

METHODS

We developed a functional magnetic resonance imaging drug-choice task to examine the choice for viewing drug-related images, rather than for actually consuming a drug. Actively using (n = 18) and abstaining (n = 19) individuals with a history of cocaine use disorder (CUD: dependence or abuse) and matched healthy control subjects (n = 26) participated.

RESULTS

Individuals with CUD, especially those actively using cocaine outside the laboratory, made more choices than control subjects to view images depicting cocaine (especially when directly compared against images depicting an alternative appetitive reinforcer [food]). Functional magnetic resonance imaging data revealed that in individuals with CUD, the act of making drug-related choices engaged brain regions implicated in choice difficulty or ambivalence (i.e., dorsal anterior cingulate cortex, which was higher in all individuals with CUD than control subjects). Drug-related choices in CUD also engaged brain regions implicated in reward (e.g., midbrain/ventral tegmental area, which was most activated in active users, although this region was not hypothesized a priori).

CONCLUSIONS

These results help clarify the neural mechanisms underlying drug-biased choice in human addiction, which, beyond mechanisms involved in value assignment or reward, may critically involve mechanisms that contribute to resolving difficult decisions. Future studies are needed to validate these behavioral and neural abnormalities as markers of drug seeking and relapse in treatment contexts.

Negative mood-induced alcohol-seeking is greater in young adults who report depression symptoms, drinking to cope, and subjective reactivity

Acute negative mood powerfully motivates alcohol-seeking behavior, but it remains unclear whether sensitivity to this effect is greater in drinkers who report depression symptoms, drinking to cope, and subjective reactivity. To examine these questions, 128 young adult alcohol drinkers (ages 18-25) completed questionnaires of alcohol use disorder symptoms, depression symptoms, and drinking to cope with negative affect. Baseline alcohol choice was measured by preference to enlarge alcohol versus food thumbnail images in two-alternative forced-choice trials. Negative mood was then induced by depressive statements and music, before alcohol choice was tested. Subjective reactivity was indexed by increased sadness pre- to post-mood induction. Baseline alcohol choice correlated with alcohol dependence symptoms (p = .001), and drinking coping motives (ps ≤ .01). Mood induction increased alcohol choice and subjective sadness overall (ps < .001). The mood-induced increase in alcohol choice was associated with depression symptoms (p = .007), drinking to cope (ps ≤ .03), and subjective reactivity (p = .007). The relationship between mood-induced alcohol choice and drinking to cope remained significant after covarying for other drinking motives. Furthermore, the three predictors (depression, drinking to cope, and subjective reactivity) accounted for unique variance in mood-induced alcohol choice (ps ≥ .03), and collectively accounted for 18% of the variance (p < .001). These findings validate the pictorial alcohol choice task as sensitive to the relative value of alcohol and acute negative mood. The findings also accord with the core prediction of negative reinforcement theory that sensitivity to the motivational impact of negative mood on alcohol-seeking behavior may be an important mechanism that links depression and alcohol dependence. (PsycINFO Database Record

Low Striatal Dopamine D2-type Receptor Availability is Linked to Simulated Drug Choice in Methamphetamine Users

Individuals with drug use disorders seek drugs over other rewarding activities, and exhibit neurochemical deficits related to dopamine, which is involved in value-based learning and decision-making. Thus, a dopaminergic disturbance may underpin drug-biased choice in addiction. Classical drug-choice assessments, which offer drug-consumption opportunities, are inappropriate for addicted individuals seeking treatment or abstaining. Fifteen recently abstinent methamphetamine users and 15 healthy controls completed two laboratory paradigms of 'simulated' drug choice (choice for drug-related vs affectively pleasant, unpleasant, and neutral images), and underwent positron emission tomography measurements of dopamine D2-type receptor availability, indicated by binding potential (BP_ND) for [¹⁸F]fallypride. Thirteen of the methamphetamine users and 10 controls also underwent [¹¹C]NNC112 PET scans to measure dopamine D1-type receptor availability. Group analyses showed that, compared with controls, methamphetamine users chose to view more methamphetamine-related images on one task, with a similar trend on the second task. Regression analyses showed that, on both tasks, the more methamphetamine users chose to view methamphetamine images, specifically vs pleasant images (the most frequently chosen images across all participants), the lower was their D2-type BP_ND in the lateral orbitofrontal cortex, an important region in value-based choice. No associations were observed with D2-type BP_ND in striatal regions, or with D1-type BP_ND in any region. These results identify a neurochemical correlate for a laboratory drug-seeking paradigm that can be administered to treatment-seeking and abstaining drug-addicted individuals. More broadly, these results refine the central hypothesis that dopamine-system deficits contribute to drug-biased decision-making in addiction, here showing a role for the orbitofrontal cortex.

Alcohol use disorder symptoms are associated with greater relative value ascribed to alcohol, but not greater discounting of costs imposed on alcohol

RATIONALE

Alcohol dependence is characterised by persistent drinking despite health, social and economic costs. Behavioural economics has proposed two explanations for the persistence of alcohol use despite costs. Dependent individuals may (a) ascribe excessively high value to alcohol, such that costs associated with alcohol are exceeded, and/or (b) they may discount (neglect) the costs associated with alcohol.

METHODS

To test these predictions, the current study recruited 127 student drinkers who reported varied alcohol use disorder symptom severity in the Alcohol Use Disorders Inventory Test (AUDIT; mean = 11.17, 69% above the hazardous cutoff). Participants made concurrent forced choices between alcohol and food points under conditions that manipulated the magnitude of points (1, 2 or 3) and the delay to receive points (0 or 3 s). Alcohol value was indexed by preferential choice of alcohol versus food points, whereas sensitivity to costs was indexed by the decrease in alcohol choice when food points were of greater magnitude (sensitivity to opportunity costs) and when alcohol points were delayed (sensitivity to delay costs).

RESULTS

Percent choice of alcohol over food varied consistently with the relative magnitude of reward points offered (p < .001) and with time delays imposed on reward points (p < .001). AUDIT scores were associated with greater alcohol versus food choice across all conditions (p = .001). As alcohol use disorder symptom severity increased, the sensitivity of alcohol choice to the relative magnitude of points (p = .29) and time delays (p = .62) remained unchanged, suggesting no differential discounting of opportunity or delay costs imposed on alcohol. In contrasts of AUDIT categories, there was comparable sensitivity to costs across groups defined as low-risk (N = 39), hazardous (n = 57), harmful (n = 20) and possible dependent drinkers (n = 11).

CONCLUSIONS

Alcohol use disorder symptom severity is associated with greater relative value ascribed to alcohol, but not with greater discounting of opportunity or delay costs imposed on alcohol. Despite limitations of the current study, it may be concluded that cost discounting plays a lesser role in dependence than previously thought.

Attentional responses to stimuli associated with a reward can occur in the absence of knowledge of their predictive values

Classical conditioning theories of addiction suggest that stimuli associated with rewards acquire incentive salience, inducing emotional and attentional conditioned responses. It is not clear whether those responses occur without contingency awareness (CA), i.e. are based on explicit or implicit learning processes. Examining implicit aspects of stimulus-reward associations can improve our understanding of addictive behaviours, supporting treatment and prevention strategies. However, the acquisition of conditioned responses without CA has yet to be rigorously demonstrated, as the existing literature shows a lack of methodological agreement regarding the measurement of implicit and explicit processes. The purpose of two experiments presented here was to study the emotional value acquired by CS through implicit emotional and attentional processes, trying to overcome critical methodological issues. Experiment 1 (n = 48) paired two stimuli categories (houses/buildings) with high (HR) or low (LR) probabilities of monetary reward. An Emotional Attentional Blink revealed preferential attention for HR over LR regardless of CA; while pleasantness ratings were unaffected, probably due to the intrinsic nature of CS. Experiment 2 (n = 60) replicated the effect of conditioning on the Emotional Attentional Blink utilising abstract CS (octagons/squares). In addition increased pleasantness for HR over LR was found significant overall, and marginally significant for Aware but not for Unaware participants. Here CA was rigorously determined using a signal-detection analysis and metacognitive-awareness measurements. Bayesian analyses verified the unconscious nature of the learning. These findings demonstrate that attentional conditioned responses can occur without CA and advance our understanding of the mechanisms by which implicit conditioning can occur and becomes observable. Furthermore, these results can highlight how addictive behaviours might develop.

Drug cue reactivity involves hierarchical instrumental learning: evidence from a biconditional Pavlovian to instrumental transfer task

RATIONALE

Drug cue reactivity plays a crucial role in addiction, yet the underlying mechanisms are poorly understood. According to the binary associative account, drug stimuli retrieve an expectation of the drug outcome, which, in turn, elicits the associated drug-seeking response (S-O-R). By contrast, according to the hierarchical account, drug stimuli retrieve an expectation that the contingency between the drug-seeking response and the drug outcome is currently more effective, promoting performance of the drug-seeking response (S:R-O).

METHODS

The current study discriminated between these two accounts using a biconditional Pavlovian-to-instrumental transfer (PIT) task with 128 alcohol drinkers. A biconditional discrimination was first trained in which two responses produced alcohol and food outcomes, respectively, and these response-outcome contingencies were reversed across two discriminative stimuli (SDs). In the PIT test, alcohol and food cues were compounded with the two SDs to examine their impact on percent alcohol choice in extinction.

RESULTS

It was found that alcohol and food cues selectively primed choice of the response that earned that outcome in each SD (p < .001), and this effect was associated with participants' belief that cues signalled greater effectiveness of that response (p < .0001).

CONCLUSIONS

The alcohol stimulus could not have selectively primed the alcohol-seeking response through binary S-O-R associations because the drug outcome was equally associated with both responses. Rather, the alcohol stimulus must have retrieved an expectation that the response-alcohol contingency available in the current context was more likely to be effective (S:R-O), which primed performance of the alcohol-seeking response.

The propositional basis of cue-controlled reward seeking

Two experiments examined the role of propositional and automatic (ideomotor) processes in cue-elicited responding for rewarding outcomes (beer and chocolate). In a training phase, participants earned either chocolate or beer points by making one of two button-press responses. Rewards were indicated by the presentation of chocolate and beer pictures. On test, each trial began with a picture of beer or chocolate, or a blank screen, and choice of the beer versus chocolate response was assessed in the presence of these three pictures. Participants tended to choose the beer and chocolate response in the presence of the beer and chocolate pictures, respectively. In Experiment 1, instructions signalling that the pictures did not indicate which response would be rewarded significantly reduced the priming effect. In Experiment 2, instructions indicating that the pictures signified which response would not be rewarded resulted in a reversed priming effect. Finally, in both experiments, the priming effect correlated with self-reported beliefs that the cues signalled which response was more likely to be reinforced. These results suggest that cue-elicited response selection is mediated by a propositional belief regarding the efficacy of the response–outcome relationship, rather than an automatic ideomotor mechanism.

Addictions Neuroclinical Assessment: A Neuroscience-Based Framework for Addictive Disorders

This article proposes a heuristic framework for the Addictions Neuroclinical Assessment that incorporates key functional domains derived from the neurocircuitry of addiction. We review how addictive disorders (ADs) are presently diagnosed and the need for new neuroclinical measures to differentiate patients who meet clinical criteria for addiction to the same agent while differing in etiology, prognosis, and treatment response. The need for a better understanding of the mechanisms provoking and maintaining addiction, as evidenced by the limitations of current treatments and within-diagnosis clinical heterogeneity, is articulated. In addition, recent changes in the nosology of ADs, challenges to current classification systems, and prior attempts to subtype individuals with ADs are described. Complementary initiatives, including the Research Domain Criteria project, that have established frameworks for the neuroscience of psychiatric disorders are discussed. Three domains-executive function, incentive salience, and negative emotionality-tied to different phases in the cycle of addiction form the core functional elements of ADs. Measurement of these domains in epidemiologic, genetic, clinical, and treatment studies will provide the underpinnings for an understanding of cross-population and temporal variation in addictions, shared mechanisms in addictive disorders, impact of changing environmental influences, and gene identification. Finally, we show that it is practical to implement such a deep neuroclinical assessment using a combination of neuroimaging and performance measures. Neuroclinical assessment is key to reconceptualizing the nosology of ADs on the basis of process and etiology, an advance that can lead to improved prevention and treatment.

Glucocorticoid Regulation of Food-Choice Behavior in Humans: Evidence from Cushing's Syndrome

The mechanisms by which glucocorticoids regulate food intake and resulting body mass in humans are not well-understood. One potential mechanism could involve modulation of reward processing, but human stress models examining effects of glucocorticoids on behavior contain important confounds. Here, we studied individuals with Cushing's syndrome, a rare endocrine disorder characterized by chronic excess endogenous glucocorticoids. Twenty-three patients with Cushing's syndrome (13 with active disease; 10 with disease in remission) and 15 controls with a comparably high body mass index (BMI) completed two simulated food-choice tasks (one with “explicit” task contingencies and one with “probabilistic” task contingencies), during which they indicated their objective preference for viewing high calorie food images vs. standardized pleasant, unpleasant, and neutral images. All participants also completed measures of food craving, and approximately half of the participants provided 24-h urine samples for assessment of cortisol and cortisone concentrations. Results showed that on the explicit task (but not the probabilistic task), participants with active Cushing's syndrome made fewer food-related choices than participants with Cushing's syndrome in remission, who in turn made fewer food-related choices than overweight controls. Corroborating this group effect, higher urine cortisone was negatively correlated with food-related choice in the subsample of all participants for whom these data were available. On the probabilistic task, despite a lack of group differences, higher food-related choice correlated with higher state and trait food craving in active Cushing's patients. Taken together, relative to overweight controls, Cushing's patients, particularly those with active disease, displayed a reduced vigor of responding for food rewards that was presumably attributable to glucocorticoid abnormalities. Beyond Cushing's, these results may have relevance for elucidating glucocorticoid contributions to food-seeking behavior, enhancing mechanistic understanding of weight fluctuations associated with oral glucocorticoid therapy and/or chronic stress, and informing the neurobiology of neuropsychiatric conditions marked by abnormal cortisol dynamics (e.g., major depression, Alzheimer's disease).

Neuroimaging markers of glutamatergic and GABAergic systems in drug addiction: Relationships to resting-state functional connectivity

Drug addiction is characterized by widespread abnormalities in brain function and neurochemistry, including drug-associated effects on concentrations of the excitatory and inhibitory neurotransmitters glutamate and gamma-aminobutyric acid (GABA), respectively. In healthy individuals, these neurotransmitters drive the resting state, a default condition of brain function also disrupted in addiction. Here, our primary goal was to review in vivo magnetic resonance spectroscopy and positron emission tomography studies that examined markers of glutamate and GABA abnormalities in human drug addiction. Addicted individuals tended to show decreases in these markers compared with healthy controls, but findings also varied by individual characteristics (e.g., abstinence length). Interestingly, select corticolimbic brain regions showing glutamatergic and/or GABAergic abnormalities have been similarly implicated in resting-state functional connectivity deficits in drug addiction. Thus, our secondary goals were to provide a brief review of this resting-state literature, and an initial rationale for the hypothesis that abnormalities in glutamatergic and/or GABAergic neurotransmission may underlie resting-state functional deficits in drug addiction. In doing so, we suggest future research directions and possible treatment implications.

Electrophysiology for addiction medicine: From methodology to conceptualization of reward deficits

In the past decade, electroencephalographic research on addiction has employed passive viewing, oddball, inhibition, prediction, gambling, and reversal learning tasks to study how substance users neurally prioritize drug-related rewards at the expense of nondrug rewards. On the whole, findings across substances (alcohol, cannabis, cocaine, nicotine, opiates, gambling, and gaming) demonstrate impairments in the differentiation of monetary incentives and the inhibition of prepotent responses. Furthermore, exaggerated resources devoted to drug cues and attenuated processing of other types of pleasant emotional stimuli predict greater probability of future drug use. However, drug use recency, frequency, sensitivity, and insight all appear to be moderators of these effects. We argue that more longitudinal studies are warranted to determine the time course of reward processing as a function of development and chronicity.

Neuroscience of inhibition for addiction medicine: from prediction of initiation to prediction of relapse

A core deficit in drug addiction is the inability to inhibit maladaptive drug-seeking behavior. Consistent with this deficit, drug-addicted individuals show reliable cross-sectional differences from healthy nonaddicted controls during tasks of response inhibition accompanied by brain activation abnormalities as revealed by functional neuroimaging. However, it is less clear whether inhibition-related deficits predate the transition to problematic use, and, in turn, whether these deficits predict the transition out of problematic substance use. Here, we review longitudinal studies of response inhibition in children/adolescents with little substance experience and longitudinal studies of already addicted individuals attempting to sustain abstinence. Results show that response inhibition and its underlying neural correlates predict both substance use outcomes (onset and abstinence). Neurally, key roles were observed for multiple regions of the frontal cortex (e.g., inferior frontal gyrus, dorsal anterior cingulate cortex, and dorsolateral prefrontal cortex). In general, less activation of these regions during response inhibition predicted not only the onset of substance use, but interestingly also better abstinence-related outcomes among individuals already addicted. The role of subcortical areas, although potentially important, is less clear because of inconsistent results and because these regions are less classically reported in studies of healthy response inhibition. Overall, this review indicates that response inhibition is not simply a manifestation of current drug addiction, but rather a core neurocognitive dimension that predicts key substance use outcomes. Early intervention in inhibitory deficits could have high clinical and public health relevance.

Cocaine choice procedures in animals, humans, and treatment-seekers: Can we bridge the divide?

Individuals with cocaine use disorder chronically self-administer cocaine to the detriment of other rewarding activities, a phenomenon best modeled in laboratory drug-choice procedures. These procedures can evaluate the reinforcing effects of drugs versus comparably valuable alternatives under multiple behavioral arrangements and schedules of reinforcement. However, assessing drug-choice in treatment-seeking or abstaining humans poses unique challenges: for ethical reasons, these populations typically cannot receive active drugs during research studies. Researchers have thus needed to rely on alternative approaches that approximate drug-choice behavior or assess more general forms of decision-making, but whether these alternatives have relevance to real-world drug-taking that can inform clinical trials is not well-understood. In this mini-review, we (A) summarize several important modulatory variables that influence cocaine choice in nonhuman animals and non-treatment seeking humans; (B) discuss some of the ethical considerations that could arise if treatment-seekers are enrolled in drug-choice studies; (C) consider the efficacy of alternative procedures, including non-drug-related decision-making and 'simulated' drug-choice (a choice is made, but no drug is administered) to approximate drug choice; and (D) suggest opportunities for new translational work to bridge the current divide between preclinical and clinical research.

Measuring anhedonia: impaired ability to pursue, experience, and learn about reward

Ribot’s (1896) long standing definition of anhedonia as “the inability to experience pleasure” has been challenged recently following progress in affective neuroscience. In particular, accumulating evidence suggests that reward consists of multiple subcomponents of wanting, liking and learning, as initially outlined by Berridge and Robinson (2003), and these processes have been proposed to relate to appetitive, consummatory and satiety phases of a pleasure cycle. Building on this work, we recently proposed to reconceptualize anhedonia as “impairments in the ability to pursue, experience, and/or learn about pleasure, which is often, but not always accessible to conscious awareness.” (Rømer Thomsen et al., 2015). This framework is in line with Treadway and Zald’s (2011) proposal to differentiate between motivational and consummatory types of anhedonia, and stresses the need to combine traditional self-report measures with behavioral measures or procedures. In time, this approach may lead to improved clinical assessment and treatment. In line with our reconceptualization, increasing evidence suggests that reward processing deficits are not restricted to impaired hedonic impact in major psychiatric disorders. Successful translations of animal models have led to strong evidence of impairments in the ability to pursue and learn about reward in psychiatric disorders such as major depressive disorder, schizophrenia, and addiction. It is of high importance that we continue to systematically target impairments in all phases of reward processing across disorders using behavioral testing in combination with neuroimaging techniques. This in turn has implications for diagnosis and treatment, and is essential for the purposes of identifying the underlying neurobiological mechanisms. Here I review recent progress in the development and application of behavioral procedures that measure subcomponents of anhedonia across relevant patient groups, and discuss methodological caveats as well as implications for assessment and treatment.

Drug versus sweet reward: greater attraction to and preference for sweet versus drug cues

Despite the unique ability of addictive drugs to directly activate brain reward circuits, recent evidence suggests that drugs induce reinforcing and incentive effects that are comparable to, or even lower than some nondrug rewards. In particular, when rats have a choice between pressing a lever associated with intravenous cocaine or heroin delivery and another lever associated with sweet water delivery, most respond on the latter. This outcome suggests that sweet water is more reinforcing and attractive than either drug. However, this outcome may also be due to the differential ability of sweet versus drug levers to elicit Pavlovian feeding-like conditioned responses that can cause involuntary lever pressing, such as pawing and biting the lever. To test this hypothesis, rats first underwent Pavlovian conditioning to associate one lever with sweet water (0.2% saccharin) and a different lever with intravenous cocaine (0.25 mg) or heroin (0.01 mg). Choice between these two levers was then assessed under two operant choice procedures: one that permitted the expression of Pavlovian-conditioned lever press responses during choice, the other not. During conditioning, Pavlovian-conditioned lever press responses were considerably higher on the sweet lever than on either drug lever, and slightly greater on the heroin lever than on the cocaine lever. Importantly, though these differences in Pavlovian-conditioned behavior predicted subsequent preference for sweet water during choice, they were not required for its expression. Overall, this study confirms that rats prefer the sweet lever because sweet water is more reinforcing and attractive than cocaine or heroin.

Concurrent access to nicotine and sucrose in rats

BACKGROUND

Animal models that allow concurrent access to drug and nondrug reinforcers provide unique insight into the etiology, maintenance, and treatment of drug use.

OBJECTIVES

We sought to develop and utilize a concurrent access procedure with nicotine and sucrose in rats.

METHODS

Pressing one lever delivered intravenous nicotine, and pressing another lever delivered sucrose pellets, with both reinforcers freely available throughout daily sessions.

RESULTS

Rats that had been pretrained with nicotine on some days and sucrose on other days responded on both levers when subsequently given concurrent access, but almost all responded at substantially higher rates on the sucrose lever. In contrast, rats pretrained exclusively with nicotine before being given concurrent access showed individual differences, with about half responding more on the nicotine lever. Treatment with the nicotinic receptor partial agonist varenicline selectively decreased nicotine self-administration. Food restriction and removal of the sucrose lever both increased nicotine self-administration.

CONCLUSIONS

The finding that rats continue to take nicotine when sucrose is concurrently available-and in many cases take it more frequently than sucrose-demonstrates that nicotine self-administration does not only occur in the absence of alternative reinforcement options. As a model of human nicotine use, concurrent access is more naturalistic and has higher face validity than procedures in which only one reinforcer is available or choosing one reinforcer precludes access to other reinforcers. As such, this procedure could be useful for evaluating therapeutic agents and improving our understanding of environmental conditions that promote or discourage nicotine use.

Reconceptualizing anhedonia: novel perspectives on balancing the pleasure networks in the human brain

Anhedonia, the lack of pleasure, has been shown to be a critical feature of a range of psychiatric disorders. Yet, it is currently measured primarily through subjective self-reports and as such has been difficult to submit to rigorous scientific analysis. New insights from affective neuroscience hold considerable promise in improving our understanding of anhedonia and for providing useful objective behavioral measures to complement traditional self-report measures, potentially leading to better diagnoses and novel treatments. Here, we review the state-of-the-art of hedonia research and specifically the established mechanisms of wanting, liking, and learning. Based on this framework we propose to conceptualize anhedonia as impairments in some or all of these processes, thereby departing from the longstanding view of anhedonia as solely reduced subjective experience of pleasure. We discuss how deficits in each of the reward components can lead to different expressions, or subtypes, of anhedonia affording novel ways of measurement. Specifically, we review evidence suggesting that patients suffering from depression and schizophrenia show impairments in wanting and learning, while some aspects of conscious liking seem surprisingly intact. Furthermore, the evidence suggests that anhedonia is heterogeneous across psychiatric disorders, depending on which parts of the pleasure networks are most affected. This in turn has implications for diagnosis and treatment of anhedonia.

Relationship between drug dreams, affect, and craving during treatment for substance dependence

OBJECTIVES

To explore the relationship between occurrence of drug dreams (DDs) and daytime negative affect and drug craving during the course of a 5-week treatment program for substance dependence.

METHODS

Using the dream journal methodology, 86 participants reported occurrence of dreams, dream content, and ratings of affect and drug craving. The relationships between the experience of DD, dream content ("active" vs "passive"), and affect and craving were analyzed using mixed model methods.

RESULTS

The experience of DD was associated with higher levels of negative affect (P < 0.001) and craving (P < 0.001). The occurrence of DD did not decrease significantly over the 5 weeks of the study. Cocaine/crack users reported a higher occurrence of DD (P < 0.05) than the other drug groups (opiates and alcohol), and DD involving "active" drug use was associated with larger (P < 0.05) changes in negative affect.

CONCLUSIONS

These results are consistent with the hypothesis that DD can act as drug-conditioned stimuli to elevate negative affect and craving in abstaining individuals. Although correlational, such findings support the implementation of psychological and pharmacological interventions aimed at minimizing the impact of DD on individuals in recovery from drug addiction.