Patterns of Brain Activation During Craving in Heroin Dependents Successfully Treated by Methadone Maintenance and Abstinence-Based Treatments

Neural mechanisms linked to treatment outcomes and recovery in substance-related and addictive disorders

The present review focuses on potential neural mechanisms underlying recovery from psychiatric conditions characterised by impaired impulse control, specifically substance use disorders, gambling disorder, and internet gaming disorder. Existing treatments (both pharmacological and psychological) for these addictions may impact brain processes, and these have been evaluated in neuroimaging studies. Medication challenge and short-term intervention administration will be considered with respect to treatment utility. Main models of addiction (e.g., dual process, reward deficiency syndrome) will be considered in the context of extant data. Additionally, advanced analytic approaches (e.g., machine-learning approaches) will be considered with respect to guiding treatment development efforts. Thus, this narrative review aims to provide directions for treatment development for addictive disorders.

Functional neuroanatomy of craving in heroin use disorder: voxel-based meta-analysis of functional magnetic resonance imaging (fMRI) drug cue reactivity studies

Background: The neuroanatomy of craving, typically investigated using the functional magnetic resonance imaging (fMRI) drug cue reactivity (FDCR) paradigm, has been shown to involve the mesocorticolimbic, nigrostriatal, and corticocerebellar systems in several substances. However, the neuroanatomy of craving in heroin use disorder is still unclear.Objective: The current meta-analysis examines previous research on the neuroanatomy of craving in abstinent individuals with opioid use disorder (OUD).Method: Seven databases were searched for studies comparing abstinent OUD versus healthy controls on drug > neutral contrast interaction at the whole-brain level. Voxel-based meta-analysis was performed using seed-based d mapping with permuted subject images (SDM-PSI). Thresholds were set at a family-wise error rate of less than 5% with the default pre-processing parameters of SDM-PSI.Results: A total of 10 studies were included (296 OUD and 187 controls). Four hyperactivated clusters were identified with Hedges' g of peaks that ranged from 0.51 to 0.82. These peaks and their associated clusters correspond to the three systems identified in the previous literature: a) mesocorticolimbic, b) nigrostriatal, and c) corticocerebellar. There were also newly revealed hyperactivation regions including the bilateral cingulate, precuneus, fusiform gyrus, pons, lingual gyrus, and inferior occipital gyrus. The meta-analysis did not reveal areas of hypoactivation.Conclusion: Recommendations based on the functional neuroanatomical findings of this meta-analysis include pharmacological interventions such as buprenorphine/naloxone and cognitive-behavioral treatments such as cue-exposure combined with HRV biofeedback. In addition, research should utilize FDCR as pre- and post-measurement to determine the effectiveness and mechanism of action of such interventions.

The effect of long-term methadone maintenance treatment on coupling among three large-scale brain networks in male heroin-dependent individuals: A resting-state fMRI study

PURPOSE

Methadone maintenance treatment (MMT) is considered as an effective and mainstream therapy for heroin dependence. However, whether long-term MMT would improve the coupling among the three core large-scale brain networks (salience, default mode, and executive control) and its relationship with the craving for heroin is unknown.

METHODS

Forty-four male heroin-dependent individuals during long-term MMT, 27 male heroin-dependent individuals after short-term detoxification/abstinence (SA), and 26 demographically matched healthy controls (HC) underwent resting-state functional magnetic resonance imaging. We analyzed the difference in coupling among the salience, default mode, and executive control networks among the three groups and examined how the coupling among these large-scale networks was associated with craving before and after drug-cue exposure.

RESULTS

Compared with the SA group, the MMT group showed lower craving before and after cue exposure and stronger connectivity between the dorsal anterior cingulate cortex (a key node of the salience network) and key regions of the bilateral executive control network, including the bilateral dorsolateral prefrontal cortex, posterior parietal cortex, and dorsomedial prefrontal cortex. Among the heroin-dependent individuals, the functional connectivity was negatively correlated with the craving before and after heroin-cue exposure.

CONCLUSION

Our findings suggest that long-term MMT could increase the coupling between the salience and bilateral executive control networks and decrease craving for heroin. These findings contribute to the understanding of the neural mechanism of MMT, from the perspective of large-scale brain networks.

Are There Neural Overlaps of Reactivity to Illegal Drugs, Tobacco, and Alcohol Cues? With Evidence From ALE and CMA

Abuses of most illegal drugs, including methamphetamine, marijuana, cocaine, heroin, and polydrug, are usually in conjunction with alcohol and tobacco. There are similarities and associations between the behavior, gene, and neurophysiology of such abusers, but the neural overlaps of their cue-reactivity and the correlation of neural overlap with drug craving still needs to be further explored. In this study, an Activation Likelihood Estimation (ALE) was performed on brain activation under legal (tobacco, alcohol) and illegal drug cues, for identifying the similarities in brain functions between different craving states. A Comprehensive meta-analysis (CMA) on the correlation coefficient between brain activation and craving scores in the selected literatures with subjective craving reports explained the degree of the craving via brain imaging results. In ALE, co-activation areas of the three cue-reactivity (posterior cingulate, caudate, and thalamus) suggest that the three cue-reactivity may all arouse drug-use identity which is a predictor of relapse and generation of conditioned reflexes under reward memory, thus leading to illegal drug relapses. In CMA, the brain activation was significantly correlated with subjective craving, with a correlation coefficient of 0.222. The neural overlap of tobacco, alcohol and most of the prevalent illegal drug cues not only further helps us understand the neural mechanism of substance co-abuse and relapse, but also provides implications to detoxification. Furthermore, the correlation between brain activation and craving is low, suggesting the accuracy of craving-based quantitative evaluation by neuroimaging remains unclear.

Chronic heroin use disorder and the brain: Current evidence and future implications

The incidence of chronic heroin use disorder, including overdose deaths, has reached epidemic proportions. Here we summarise and evaluate our knowledge of the relationship between chronic heroin use disorder and the brain through a narrative review. A broad range of areas was considered including causal mechanisms, cognitive and neurological consequences of chronic heroin use and novel neuroscience-based clinical interventions. Chronic heroin use is associated with limited or very limited evidence of impairments in memory, cognitive impulsivity, non-planning impulsivity, compulsivity and decision-making. Additionally, there is some evidence for certain neurological disorders being caused by chronic heroin use, including toxic leukoencephalopathy and neurodegeneration. However, there is insufficient evidence on whether these impairments and disorders recover after abstinence. Whilst there is a high prevalence of comorbid psychiatric disorders, there is no clear evidence that chronic heroin use per se causes depression, bipolar disorder, PTSD and/or psychosis. Despite the growing burden on society from heroin use, knowledge of the long-term effects of chronic heroin use disorder on the brain remains limited. Nevertheless, there is evidence for progress in neuroscience-based interventions being made in two areas: assessment (cognitive assessment and neuroimaging) and interventions (cognitive training/remediation and neuromodulation). Longitudinal studies are needed to unravel addiction and neurotoxic mechanisms and clarify the role of pre-existing psychiatric symptoms and cognitive impairments.

Addiction and the cerebellum with a focus on actions of opioid receptors

Increasing evidence suggests that the cerebellum could play a role in the higher cognitive processes involved in addiction as the cerebellum contains anatomical and functional pathways to circuitry controlling motivation and saliency. In addition, the cerebellum exhibits a widespread presence of receptors, including opioid receptors which are known to play a prominent role in synaptic and circuit mechanisms of plasticity associated with drug use and development of addiction to opioids and other drugs of abuse. Further, the presence of perineural nets (PNNs) in the cerebellum which contain proteins known to alter synaptic plasticity could contribute to addiction. The role the cerebellum plays in processes of addiction is likely complex, and could depend on the particular drug of abuse, the pattern of use, and the stage of the user within the addiction cycle. In this review, we discuss functional and structural modifications shown to be produced in the cerebellum by opioids that exhibit dependency-inducing properties which provide support for the conclusion that the cerebellum plays a role in addiction.

An instrument for visual cue associated craving of HEroin (IV-CACHE): A preliminary functional neuroimaging-based study of validity and reliability

BACKGROUND

Craving is the subjective experience of desire for specific drugs. Lack of reliability and untested construct validity are limiting factors for the existing questionnaires to assess craving.

AIM

The aim of the study was to design and test the validity and reliability of an instrument to assess visual cue-induced craving for heroin dependence.

MATERIALS AND METHODS

In the first stage of the study, a set of forty images (twenty each of heroin and neutral cues-) were captured and validated by expert consensus. Thirty male participants with heroin dependence rated their cue-induced craving on a six-point Likert scale while viewing this image-set. In the next stage, putative construct validity was examined using a pilot cue-reactivity functional magnetic resonance imaging paradigm with ten additional heroin-dependent patients.

RESULTS

Cronbach's alpha for the instrument for visual cue-associated craving of HEroin (IV-CACHE) was 0.9, suggestive of high internal consistency. There were modest and significant correlations of IV-CACHE with the drug desire questionnaire (r = 0.43), and obsessive-compulsive drug use scale (r = 0.37), supporting concurrent validity. Patients with heroin dependence exhibited cue reactivity in the left fusiform area, right lingual gyrus, right precuneus region, right inferior frontal, inferior temporal gyri, and middle occipital gyri. The activated brain areas were largely aligned to the underlying neurobiological substrates of craving but might also have depicted nondrug-specific factors (aberrant face processing and attentional bias).

CONCLUSION

The present cue-task is a promising tool for the examination of cue-related craving for heroin in the Indian setting.

Assessing effect of long-term abstinence on coupling of three core brain networks in male heroin addicts: A resting-state functional magnetic resonance imaging study

Abstinence is one of the important measures for heroin addiction. However, it is unknown whether long-term abstinence (LA) would improve the coupling among three core brain networks (salience, default mode, and executive control) and decrease craving in treated heroin addicts. Forty-three heroin addicts with LA, 27 heroin addicts with short-term abstinence (SA), and 46 demographically matched healthy controls (HC) participated in the resting-state functional magnetic resonance imaging study. The authors compared the functional connectivity among the three groups and examined how the coupling among salience, default mode, and executive control networks related to duration of abstinence and craving before and after drug cue exposure among heroin addicts. Compared with the SA group, with a tendency toward the HC group, the LA group showed lower drug cue-induced craving, stronger connectivity between the dorsal anterior cingulate cortex (a key node of salience network) and left dorsolateral prefrontal cortex and right posterior parietal cortex (key nodes of executive control network), and stronger connectivity between the right dorsolateral prefrontal cortex and precuneus (a key node of default mode network). Meanwhile, the right dorsolateral prefrontal cortex-precuneus connectivity positively correlated with duration of abstinence. The LA and SA groups demonstrated lower connectivity between the left anterior insula (a key node of salience network) and dorsolateral prefrontal cortex and lower connectivity within the left dorsolateral prefrontal cortex, compared with the HC group. Our findings revealed that LA is associated with lower drug cue induced craving and improve the coupling among the three core brain networks in heroin addicts.

Early Life Stress and Risks for Opioid Misuse: Review of Data Supporting Neurobiological Underpinnings

A robust body of research has shown that traumatic experiences occurring during critical developmental periods of childhood when neuronal plasticity is high increase risks for a spectrum of physical and mental health problems in adulthood, including substance use disorders. However, until recently, relatively few studies had specifically examined the relationships between early life stress (ELS) and opioid use disorder (OUD). Associations with opioid use initiation, injection drug use, overdose, and poor treatment outcome have now been demonstrated. In rodents, ELS has also been shown to increase the euphoric and decrease antinociceptive effects of opioids, but little is known about these processes in humans or about the neurobiological mechanisms that may underlie these relationships. This review aims to establish a theoretical model that highlights the mechanisms by which ELS may alter opioid sensitivity, thereby contributing to future risks for OUD. Alterations induced by ELS in mesocorticolimbic brain circuits, and endogenous opioid and dopamine neurotransmitter systems are described. The limited but provocative evidence linking these alterations with opioid sensitivity and risks for OUD is presented. Overall, the findings suggest that better understanding of these mechanisms holds promise for reducing vulnerability, improving prevention strategies, and prescribing guidelines for high-risk individuals.

Craving and opioid use disorder: A scoping review

INTRODUCTION

The subjective experience of drug craving is a prominent and common clinical phenomenon for many individuals diagnosed with opioid use disorder (OUD), and could be a valuable clinical endpoint in medication development studies. The purpose of this scoping review is to provide an overview and critical analysis of opioid craving assessments located in the published literature examining OUD.

METHOD

Studies were identified through a search of PubMed, Embase, and PsychInfo databases and included for review if opioid craving was the focus and participants were diagnosed with or in treatment for OUD.

RESULTS

Fifteen opioid craving assessment instruments were identified across the 87 studies included for review. The most common were the Visual Analog Scale (VAS, 41 studies), Desires for Drug Questionnaire (DDQ, 12 studies), Heroin Craving Questionnaire (HCQ, 10 studies), and Obsessive-Compulsive Drug Use Scale (OCDUS, 10 studies). Craving assessments varied considerably in their format, content, time frame, and underlying subscales, and only 6 of 15 had been psychometrically evaluated.

DISCUSSION

This review identified a variety of opioid craving assessments, but few had been evaluated for their psychometric properties making it difficult to ascertain whether craving is being assessed optimally in studies of OUD. Thus, the development of a reliable and valid opioid craving assessment would be worthwhile and could be guided by recently published Food and Drug Administration Clinical Outcome Assessment (COA) guidelines. Importantly, a COA focused on opioid craving could be a valuable addition to research studies designed to evaluate novel treatments for OUD.

Neuroimaging Impaired Response Inhibition and Salience Attribution in Human Drug Addiction: A Systematic Review

The impaired response inhibition and salience attribution (iRISA) model proposes that impaired response inhibition and salience attribution underlie drug seeking and taking. To update this model, we systematically reviewed 105 task-related neuroimaging studies (n > 15/group) published since 2010. Results demonstrate specific impairments within six large-scale brain networks (reward, habit, salience, executive, memory, and self-directed networks) during drug cue exposure, decision making, inhibitory control, and social-emotional processing. Addicted individuals demonstrated increased recruitment of these networks during drug-related processing but a blunted response during non-drug-related processing, with the same networks also being implicated during resting state. Associations with real-life drug use, relapse, therapeutic interventions, and the relevance to initiation of drug use during adolescence support the clinical relevance of the results. Whereas the salience and executive networks showed impairments throughout the addiction cycle, the reward network was dysregulated at later stages of abuse. Effects were similar in alcohol, cannabis, and stimulant addiction.

Time-dependent regional brain distribution of methadone and naltrexone in the treatment of opioid addiction

Opioid addiction is a serious public health concern with severe health and social implications; therefore, extensive therapeutic efforts are required to keep users drug free. The two main pharmacological interventions, in the treatment of addiction, involve management with methadone an mu (μ)-opioid agonist and treatment with naltrexone, μ-opioid, kappa (κ)-opioid and delta (δ)-opioid antagonist. MET and NAL are believed to help individuals to derive maximum benefit from treatment and undergo a full recovery. The aim of this study was to determine the localization and distribution of MET and NAL, over a 24-hour period in rodent brain, in order to investigate the differences in their respective regional brain distributions. This would provide a better understanding of the role of each individual drug in the treatment of addiction, especially NAL, whose efficacy is controversial. Tissue distribution was determined by using mass spectrometric imaging (MSI), in combination with quantification via liquid chromatography tandem mass spectrometry. MSI image analysis showed that MET was highly localized in the striatal and hippocampal regions, including the nucleus caudate, putamen and the upper cortex. NAL was distributed with high intensities in the mesocorticolimbic system including areas of the cortex, caudate putamen and ventral pallidum regions. Our results demonstrate that MET and NAL are highly localized in the brain regions with a high density of μ-receptors, the primary sites of heroin binding. These areas are strongly implicated in the development of addiction and are the major pathways that mediate brain stimulation during reward.

Forging Neuroimaging Targets for Recovery in Opioid Use Disorder

The United States is in the midst of an opioid epidemic and lacks a range of successful interventions to reduce this public health burden. Many individuals with opioid use disorder (OUD) consume drugs to relieve physical and/or emotional pain, a pattern that may increasingly result in death. The field of addiction research lacks a comprehensive understanding of physiological and neural mechanisms instantiating this cycle of Negative Reinforcement in OUD, resulting in limited interventions that successfully promote abstinence and recovery. Given the urgency of the opioid crisis, the present review highlights faulty brain circuitry and processes associated with OUD within the context of the Three-Stage Model of Addiction (1). This model underscores Negative Reinforcement processes as crucial to the maintenance and exacerbation of chronic substance use together with Binge/Intoxication and Preoccupation/Anticipation processes. This review focuses on cross-sectional as well as longitudinal studies of relapse and treatment outcome that employ magnetic resonance imaging (MRI), functional near-infrared spectroscopy (fNIRs), brain stimulation methods, and/or electroencephalography (EEG) explored in frequency and time domains (the latter measured by event-related potentials, or ERPs). We discuss strengths and limitations of this neuroimaging work with respect to study design and individual differences that may influence interpretation of findings (e.g., opioid use chronicity/recency, comorbid symptoms, and biological sex). Lastly, we translate gaps in the OUD literature, particularly with respect to Negative Reinforcement processes, into future research directions involving operant and classical conditioning involving aversion/stress. Overall, opioid-related stimuli may lessen their hold on frontocingulate mechanisms implicated in Preoccupation/Anticipation as a function of prolonged abstinence and that degree of frontocingulate impairment may predict treatment outcome. In addition, longitudinal studies suggest that brain stimulation/drug treatments and prolonged abstinence can change brain responses during Negative Reinforcement and Preoccupation/Anticipation to reduce salience of drug cues, which may attenuate further craving and relapse. Incorporating this neuroscience-derived knowledge with the Three-Stage Model of Addiction may offer a useful plan for delineating specific neurobiological targets for OUD treatment.

Neuroscience-informed psychoeducation for addiction medicine: A neurocognitive perspective

Psychoeducation (PE) is defined as an intervention with systematic, structured, and didactic knowledge transfer for an illness and its treatment, integrating emotional and motivational aspects to enable patients to cope with the illness and to improve its treatment adherence and efficacy. PE is considered an important component of treatment in both medical and psychiatric disorders, especially for mental health disorders associated with lack of insight, such as alcohol and substance use disorders (ASUDs). New advancements in neuroscience have shed light on how various aspects of ASUDs may relate to neural processes. However, the actual impact of neuroscience in the real-life clinical practice of addiction medicine is minimal. In this chapter, we provide a perspective on how PE in addiction medicine can be informed by neuroscience in two dimensions: content (knowledge we transfer in PE) and structure (methods we use to deliver PE). The content of conventional PE targets knowledge about etiology of illness, treatment process, adverse effects of prescribed medications, coping strategies, family education, and life skill training. Adding neuroscience evidence to the content of PE could be helpful in communicating not only the impact of drug use but also the beneficial impact of various treatments (i.e., on brain function), thus enhancing motivation for compliance and further destigmatizing their symptoms. PE can also be optimized in its "structure" by implicitly and explicitly engaging different neurocognitive processes, including salience/attention, memory, and self-awareness. There are many interactions between these two dimensions, structure and content, in the delivery of neuroscience-informed psychoeducation (NIPE). We explore these interactions in the development of a cartoon-based NIPE to promote brain recovery during addiction treatment as a part of the brain awareness for addiction recovery initiative.

The cerebellum in drug craving

Craving has been considered one of the core features of addiction. It can be defined as the urge or conscious desire to use a drug elicited by the drug itself, drug-associated cues or stressors. Craving plays a major role in relapse, even after prolonged periods of abstinence, as well as in the maintenance of drug seeking in non-abstinent addicts. The circuitry of craving includes medial parts of the prefrontal cortex, ventral striatal zones, ventral tegmental area, ventral pallidum, and limbic regions. Interestingly, the cerebellum shows reciprocal loops with many of these areas. The cerebellum has been linked traditionally to motor functions but increasing evidence indicates that this part of the brain is also involved in functions related to cognition, prediction, learning, and memory. Moreover, the functional neuroimaging studies that have addressed the study of craving in humans repeatedly demonstrate cerebellar activation when craving is elicited by the presentation of drug-related cues. However, the role of cerebellar activity in these craving episodes remains unknown. Therefore, the main goal of this review is to provide a brief update on craving studies and the traditional neural basis of this phenomenon, and then discuss and propose a hypothesis for the function of the cerebellum in craving episodes.

Neuroimaging the Effectiveness of Substance Use Disorder Treatments

Neuroimaging techniques to measure the function and biochemistry of the human brain such as positron emission tomography (PET), proton magnetic resonance spectroscopy ((1)H MRS), and functional magnetic resonance imaging (fMRI), are powerful tools for assessing neurobiological mechanisms underlying the response to treatments in substance use disorders. Here, we review the neuroimaging literature on pharmacological and behavioral treatment in substance use disorder. We focus on neural effects of medications that reduce craving (e.g., naltrexone, bupropion hydrochloride, baclofen, methadone, varenicline) and that improve cognitive control (e.g., modafinil, N-acetylcysteine), of behavioral treatments for substance use disorders (e.g., cognitive bias modification training, virtual reality, motivational interventions) and neuromodulatory interventions such as neurofeedback and transcranial magnetic stimulation. A consistent finding for the effectiveness of therapeutic interventions identifies the improvement of executive control networks and the dampening of limbic activation, highlighting their values as targets for therapeutic interventions in substance use disorders.

Neuroscience of drug craving for addiction medicine: From circuits to therapies

Drug craving is a dynamic neurocognitive emotional-motivational response to a wide range of cues, from internal to external environments and from drug-related to stressful or affective events. The subjective feeling of craving, as an appetitive or compulsive state, could be considered a part of this multidimensional process, with modules in different levels of consciousness and embodiment. The neural correspondence of this dynamic and complex phenomenon may be productively investigated in relation to regional, small-scale networks, large-scale networks, and brain states. Within cognitive neuroscience, this approach has provided a long list of neural and cognitive targets for craving modulations with different cognitive, electrical, or pharmacological interventions. There are new opportunities to integrate different approaches for carving management from environmental, behavioral, psychosocial, cognitive, and neural perspectives. By using cognitive neuroscience models that treat drug craving as a dynamic and multidimensional process, these approaches may yield more effective interventions for addiction medicine.

Functional neuroimaging for addiction medicine: From mechanisms to practical considerations

During last 20 years, neuroimaging with functional magnetic resonance imaging (fMRI) in people with drug addictions has introduced a wide range of quantitative biomarkers from brain's regional or network level activities during different cognitive functions. These quantitative biomarkers could be potentially used for assessment, planning, prediction, and monitoring for "addiction medicine" during screening, acute intoxication, admission to a program, completion of an acute program, admission to a long-term program, and postgraduation follow-up. In this chapter, we have briefly reviewed main neurocognitive targets for fMRI studies associated with addictive behaviors, main study types using fMRI among drug dependents, and potential applications for fMRI in addiction medicine. Main challenges and limitations for extending fMRI studies and evidences aiming at clinical applications in addiction medicine are also discussed. There is still a significant gap between available evidences from group-based fMRI studies and personalized decisions during daily practices in addiction medicine. It will be important to fill this gap with large-scale clinical trials and longitudinal studies using fMRI measures with a well-defined strategic plan for the future.

Reward processing in obesity, substance addiction and non-substance addiction

Similarities and differences between obesity and addiction are a prominent topic of ongoing research. We conducted an activation likelihood estimation meta-analysis on 87 studies in order to map the functional magnetic resonance imaging (fMRI) response to reward in participants with obesity, substance addiction and non-substance (or behavioural) addiction, and to identify commonalities and differences between them. Our study confirms the existence of alterations during reward processing in obesity, non-substance addiction and substance addiction. Specifically, participants with obesity or with addictions differed from controls in several brain regions including prefrontal areas, subcortical structures and sensory areas. Additionally, participants with obesity and substance addictions exhibited similar blood-oxygen-level-dependent fMRI hyperactivity in the amygdala and striatum when processing either general rewarding stimuli or the problematic stimuli (food and drug-related stimuli, respectively). We propose that these similarities may be associated with an enhanced focus on reward--especially with regard to food or drug-related stimuli--in obesity and substance addiction. Ultimately, this enhancement of reward processes may facilitate the presence of compulsive-like behaviour in some individuals or under some specific circumstances. We hope that increasing knowledge about the neurobehavioural correlates of obesity and addictions will lead to practical strategies that target the high prevalence of these central public health challenges.