Circuitry of self-control and its role in reducing addiction

tDCS in Addiction and Impulse Control Disorders

The study of addiction and impulsion control disorders has shown that behaviors of seeking and consumption of addictive substances are subserved by neurobiological alterations specifically related to brain networks for reward, stress, and executive control, representing the brain's adaptation to the continued use of an addictive substance. In parallel, studies using neuromodulation techniques such as transcranial direct current stimulation (tDCS) have demonstrated promising effects in modulating cognitive and motor functions. This review aims to describe the neurobiology of addiction and some of the most relevant cognitive models of addictive behavior and to clarify how tDCS application modulates the intake and craving for several addictive substances, such as food, alcohol, nicotine, cocaine, crack, methamphetamine, and cannabis. We also discuss the positive and null outcomes of the use of this neuromodulatory technique in the treatment of addiction disorders resulting from the use of these substances. The reviewed findings lead us to conclude that tDCS interventions hold several promising clinical avenues in addiction and impulsive control. However, methodological investigations are necessary for undercover optimal parameters before implementing its clinical application.

Mindfulness and Cognitive Training in a CBT-resistant Patient With Gambling Disorder: A Combined Therapy to Enhance Self-control

: Despite the major health consequences of problem gambling, such as suicide, over-indebtedness, delinquency, or family problems, there is currently no approved drug available for the treatment of problem gambling. The efficacy of cognitive behavioral therapies (CBTs) has been demonstrated repeatedly. However, some people seem resistant to conventional CBT alone. We present the case of a 59-year-old woman with a gambling disorder, who relapsed, despite a CBT-based intervention, and who then received a combined therapy aiming to enhance self-control: a mindfulness-based therapy and cognitive training targeting inhibition.

Drug Refraining and Seeking Potentiate Synapses on Distinct Populations of Accumbens Medium Spiny Neurons

Cocaine-associated cues and contexts can precipitate drug seeking in humans and in experimental animals. Glutamatergic synapses in the core subcompartment of the nucleus accumbens (NAcore) undergo transient potentiation in response to presenting drug-associated cues. The NAcore contains two populations of medium spiny neurons (MSNs) that differentially express D1 or D2 dopamine receptors. By recording the ratio of AMPA and NMDA glutamate receptor currents (AMPA/NMDA ratio) from MSNs in NAcore tissue slices, we endeavored to understand which subpopulation of MSNs was undergoing transient potentiation. Transgenic female and male mice differentially expressing fluorescent reporters in D1 or D2 MSNs were withdrawn for 2-3 weeks after being trained to self-administer cocaine. In some mice, discrete cocaine-conditioned cues were isolated from the drug-associated context via extinction training, which causes rodents to refrain from drug seeking in the extinguished context. By measuring AMPA/NMDA ratios in the drug context with or without contextual or discrete cues, and with or without extinction training, we made the following three discoveries: (1) mice refraining from cocaine seeking in the extinguished context showed selective elevation in AMPA/NMDA ratios in D2 MSNs; (2) without extinction training, the drug-associated context selectively increased AMPA/NMDA ratios in D1 MSNs; (3) mice undergoing cue-induced cocaine seeking after extinction training in the drug-associated context showed AMPA/NMDA ratio increases in both D1 and D2 MSNs. These findings reveal that the NAcore codes drug seeking through transient potentiation of D1 MSNs, and that refraining from cocaine seeking in an extinguished context is coded through transient potentiation of D2 MSNs.SIGNIFICANCE STATEMENT Relapse is a primary symptom of addiction that can involve competition between the desire to use drugs and the desire to refrain from using drugs. Drug-associated cues induce relapse, which is correlated with transiently potentiated glutamatergic synapses in the nucleus accumbens core. We determined which of two cell populations in the accumbens core, D1-expressing or D2-expressing neurons, undergo transient synaptic potentiation. After being trained to self-administer cocaine, mice underwent withdrawal, some with and others without extinguishing responding in the drug-associated context. Extinguished mice showed transient potentiation in D2-expressing neurons in the extinguished environment, and all mice engaged in context-induced or cue-induced drug seeking showed transient potentiation of D1-expressing neurons. A simple binary engram in accumbens for seeking drugs and refraining from drugs offers opportunities for cell-specific therapies.

Open monitoring meditation reduces the involvement of brain regions related to memory function

Mindfulness meditation consists of focused attention meditation (FAM) and open monitoring meditation (OMM), both of which reduce activation of the default mode network (DMN) and mind-wandering. Although it is known that FAM requires intentional focused attention, the mechanisms of OMM remain largely unknown. To investigate this, we examined striatal functional connectivity in 17 experienced meditators (mean total practice hours = 920.6) during pre-resting, meditation, and post-resting states comparing OMM with FAM, using functional magnetic resonance imaging. Both FAM and OMM reduced functional connectivity between the striatum and posterior cingulate cortex, which is a core hub region of the DMN. Furthermore, OMM reduced functional connectivity of the ventral striatum with both the visual cortex related to intentional focused attention in the attentional network and retrosplenial cortex related to memory function in the DMN. In contrast, FAM increased functional connectivity in these regions. Our findings suggest that OMM reduces intentional focused attention and increases detachment from autobiographical memory. This detachment may play an important role in non-judgmental and non-reactive attitude during OMM. These findings provide new insights into the mechanisms underlying the contribution of OMM to well-being and happiness.

Towards a human self-regulation system: Common and distinct neural signatures of emotional and behavioural control

Self-regulation refers to controlling our emotions and actions in the pursuit of higher-order goals. Although research suggests commonalities in the cognitive control of emotion and action, evidence for a shared neural substrate is scant and largely circumstantial. Here we report on two large-scale meta-analyses of human neuroimaging studies on emotion or action control, yielding two fronto-parieto-insular networks. The networks’ overlap, however, was restricted to four brain regions: posteromedial prefrontal cortex, bilateral anterior insula, and right temporo-parietal junction. Conversely, meta-analytic contrasts revealed major between-network differences, which were independently corroborated by clustering domain-specific regions based on their intrinsic functional connectivity, as well as by functionally characterizing network sub-clusters using the BrainMap database for quantitative forward and reverse inference. Collectively, our analyses identified a core system for implementing self-control across emotion and action, beyond which, however, either regulation facet appears to rely on broadly similar yet distinct subnetworks. These insights into the neurocircuitry subserving affective and executive facets of self-control suggest both processing commonalities and differences between the two aspects of human self-regulation.

Shaping vulnerability to addiction - the contribution of behavior, neural circuits and molecular mechanisms

Substance use disorders continue to impose increasing medical, financial and emotional burdens on society in the form of morbidity and overdose, family disintegration, loss of employment and crime, while advances in prevention and treatment options remain limited. Importantly, not all individuals exposed to abused substances effectively develop the disease. Genetic factors play a significant role in determining addiction vulnerability and interactions between innate predisposition, environmental factors and personal experiences are also critical. Thus, understanding individual differences that contribute to the initiation of substance use as well as on long-term maladaptations driving compulsive drug use and relapse propensity is of critical importance to reduce this devastating disorder. In this paper, we discuss current topics in the field of addiction regarding individual vulnerability related to behavioral endophenotypes, neural circuits, as well as genetics and epigenetic mechanisms. Expanded knowledge of these factors is of importance to improve and personalize prevention and treatment interventions in the future.

Effects of a brief mindfulness-meditation intervention on neural measures of response inhibition in cigarette smokers

Research suggests that mindfulness-practices may aid smoking cessation. Yet, the neural mechanisms underlying the effects of mindfulness-practices on smoking are unclear. Response inhibition is a main deficit in addiction, is associated with relapse, and could therefore be a candidate target for mindfulness-based practices. The current study hence investigated the effects of a brief mindfulness-practice on response inhibition in smokers using behavioral and electroencephalography (EEG) measures. Fifty participants (33 females, mean age 20 years old) underwent a protocol of cigarette exposure to induce craving (cue-exposure) and were then randomly assigned to a group receiving mindfulness-instructions or control-instructions (for 15 minutes approximately). Immediately after this, they performed a smoking Go/NoGo task, while their brain activity was recorded. At the behavioral level, no group differences were observed. However, EEG analyses revealed a decrease in P3 amplitude during NoGo vs. Go trials in the mindfulness versus control group. The lower P3 amplitude might indicate less-effortful response inhibition after the mindfulness-practice, and suggest that enhanced response inhibition underlies observed positive effects of mindfulness on smoking behavior.

Intra-accumbens Raclopride Administration Prevents Behavioral Changes Induced by Intermittent Access to Sucrose Solution

Overeating is one of the most relevant clinical features in Binge Eating Disorder and in some obesity patients. According to several studies, alterations in the mesolimbic dopaminergic transmission produced by non-homeostatic feeding behavior may be associated with changes in the reward system similar to those produced by drugs of abuse. Although it is known that binge-eating is related with changes in dopaminergic transmission mediated by D2 receptors in the nucleus accumbens shell (NAcS), it has not been determined whether these receptors may be a potential target for the treatment of eating pathology with binge-eating. Accordingly, the aim of the present study was to evaluate whether sugar binging induced by intermittent access to a sucrose solution produced changes in the structure of feeding behavior and whether blocking D2 receptors prevented these changes. We used the intermittent access model to a 10% sucrose solution (2 h/day for 4 weeks) to induce sugar binging in Sprague Dawley female rats. Experimental subjects consumed in a 2-h period more than 50% of the caloric intake consumed by the subjects with ad-lib access to the sweetened solution without any increase in body weight or fat accumulation. Furthermore, we evaluated whether sugar binging was associated to the estrous cycle and we did not find differences in caloric intake (estrous vs. diestrus). Subsequently, we characterized the structure of feeding behavior (microstructural analysis) and the motivation for palatable food (breakpoints) of the subjects with sugar binging and found that feeding episodes had short latencies, high frequencies, as well as short durations and inter-episode intervals. The intermittent access model did not increase breakpoints, as occurred in subjects with ad-lib access to the sucrose. Finally, we evaluated the effects of D2 receptor blockade in the NAcS, and found that raclopride (18 nM) prevented the observed changes in the frequency and duration of episodes induced by intermittent access to the sucrose solution. Our results suggest that alterations in behavioral patterns associated with binge-eating behavior depend in part on the dopaminergic transmission in the NAcS and that the antagonism of D2 receptors may be a therapeutic tool for feeding pathology with binge-eating.

Biobehavioral Mechanisms of Mindfulness as a Treatment for Chronic Stress: An RDoC Perspective

Mindfulness-based interventions have been heralded as promising means of alleviating chronic stress. While meta-analyses indicate that mindfulness-based interventions significantly reduce global measures of stress, how mindfulness-based interventions modulate the specific mechanisms underpinning chronic stress as operationalized by the National Institute of Mental Health research domain criteria (RDoC) of sustained threat has not yet been detailed in the literature. To address this knowledge gap, this article aims to (1) review evidence that mindfulness-based interventions ameliorate each of the 10 elements of behavioral dysregulation characterizing sustained threat via an array of mindful counter-regulatory strategies; (2) review evidence that mindfulness-based interventions modify biological domains implicated in sustained threat, such as the hypothalamic–pituitary–adrenal axis, as well as brain circuits involved in attentional function, limbic reactivity, habit behavior, and the default mode network; and (3) integrate these findings into a novel conceptual framework of mindful self-regulation in the face of stress—the Mindfulness-to-Meaning Theory. Taken together, the extant body of scientific evidence suggests that the practice of mindfulness enhances a range biobehavioral factors implicated in adaptive stress coping and induces self-referential plasticity, leading to the ability to find meaning in adversity. These mechanistic findings can inform the treatment development process to optimize the next generation of mindfulness-based interventions for greater therapeutic efficacy.

Overlapping Neural Endophenotypes in Addiction and Obesity

Impulsivity refers to a tendency to act rapidly without full consideration of consequences. The trait is thought to result from the interaction between high arousal responses to potential rewards and poor self-control. Studies have suggested that impulsivity confers vulnerability to both addiction and obesity. However, results in this area are unclear, perhaps due to the high phenotypic complexity of addictions and obesity. Focusing on impulsivity, the aim of this review is to tackle the putative overlaps between addiction and obesity in four domains: (1) personality research, (2) neurocognitive tasks, (3) brain imaging, and (4) clinical evidence. We suggest that three impulsivity-related domains are particularly relevant for our understanding of similarities between addiction and obesity: lower self-control (high Disinhibition/low Conscientiousness), reward sensitivity (high Extraversion/Positive Emotionality), and negative affect (high Neuroticism/Negative Emotionality). Neurocognitive studies have shown that obesity and addiction are both associated with increased impulsive decision-making and attention bias in response to drug or food cues, respectively. Mirroring this, obesity and different forms of addiction seem to exhibit similar alterations in functional MRI brain activity in response to reward processing and during self-control tasks. Overall, our review provides an integrative approach to understand those facets of obesity that present similarities to addictive behaviors. In addition, we suggest that therapeutic interventions targeting inhibitory control may represent a promising approach for the prevention and/or treatment of obesity.

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.

Dissociable effects of systemic and orbitofrontal administration of adrenoceptor antagonists on yohimbine-induced motor impulsivity

The α₂-adrenoceptor antagonist, yohimbine, is commonly used as a pharmacological stressor. Its behavioural effects are typically attributed to elevated noradrenaline release via blockade of central, inhibitory autoreceptors. We have previously reported that yohimbine increases motor impulsivity in rats on the five-choice serial reaction time task (5CSRTT), a cognitive behavioural assessment which measures motor impulsivity and visuospatial attention. Furthermore, this effect depended on cyclic adenomonophosphate (cAMP) signalling via cAMP response element binding (CREB) protein in the orbitofrontal cortex (OFC). However, the role of specific adrenoceptors in this effect is not well-characterised. We therefore investigated whether the pro-impulsive effects of systemic yohimbine could be reproduced by direct administration into the OFC, or attenuated by intra-OFC or systemic administration of prazosin and propranolol-antagonists at the α₁- and β-adrenoceptor, respectively. Male Long-Evans rats were trained on the 5CSRTT and implanted with guide cannulae aimed at the OFC. Systemically administered α₁- or β-adrenoceptor antagonists attenuated yohimbine-induced increases in premature responding. In contrast, local infusion of yohimbine into the OFC reduced such impulsive responding, while blockade of α₁- or β-adrenoceptors within the OFC had no effect on either basal or yohimbine-stimulated motor impulsivity. Direct administration of selective antagonists at the α₁-, α₂- or β-adrenoceptor into the OFC therefore produce clearly dissociable effects from systemic administration. Collectively, these data suggest that the pro-impulsivity effect of yohimbine can be modulated by adrenergic signalling in brain areas outside of the OFC, in addition to non-adrenergic signalling pathways within the OFC.

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

RATIONALE

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Climbing Brain Levels of Organisation from Genes to Consciousness

Given the tremendous complexity of brain organisation, here I propose a strategy that dynamically links stages of brain organisation from genes to consciousness, at four privileged structural levels: genes; transcription factors (TFs)-gene networks; synaptic epigenesis; and long-range connectivity. These structures are viewed as nested and reciprocally inter-regulated, with a hierarchical organisation that proceeds on different timescales during the course of evolution and development. Interlevel bridging mechanisms include intrinsic variation-selection mechanisms, which offer a community of bottom-up and top-down models linking genes to consciousness in a stepwise manner.

Cocaine self-administration disrupted by the N-methyl-D-aspartate receptor antagonist ketamine: a randomized, crossover trial

Repeated drug consumption may progress to problematic use by triggering neuroplastic adaptations that attenuate sensitivity to natural rewards while increasing reactivity to craving and drug cues. Converging evidence suggests a single sub-anesthetic dose of the N-methyl-D-aspartate receptor antagonist ketamine may work to correct these neuroadaptations and restore motivation for non-drug rewards. Using an established laboratory model aimed at evaluating behavioral shifts in the salience of cocaine now vs money later, we found that ketamine, as compared to the control, significantly decreased cocaine self-administration by 67% relative to baseline at greater than 24 h post-infusion, the most robust reduction observed to date in human cocaine users and the first to involve mechanisms other than stimulant or dopamine agonist effects. These findings signal new directions in medication development for substance use disorders.

A translational neuroscience perspective on mindfulness meditation as a prevention strategy

Mindfulness meditation research mainly focuses on psychological outcomes such as behavioral, cognitive, and emotional functioning. However, the neuroscience literature on mindfulness meditation has grown in recent years. This paper provides an overview of relevant neuroscience and psychological research on the effects of mindfulness meditation. We propose a translational prevention framework of mindfulness and its effects. Drawing upon the principles of prevention science, this framework integrates neuroscience and prevention research and postulates underlying brain regulatory mechanisms that explain the impact of mindfulness on psychological outcomes via self-regulation mechanisms linked to underlying brain systems. We conclude by discussing potential clinical and practice implications of this model and directions for future research.

Developing brain networks of attention

PURPOSE OF REVIEW

Attention is a primary cognitive function critical for perception, language, and memory. We provide an update on brain networks related to attention, their development, training, and pathologies.

RECENT FINDINGS

An executive attention network, also called the cingulo-opercular network, allows voluntary control of behavior in accordance with goals. Individual differences among children in self-regulation have been measured by a higher order factor called effortful control, which is related to the executive network and to the size of the anterior cingulate cortex.

SUMMARY

Brain networks of attention arise in infancy and are related to individual differences, including pathology during childhood. Methods of training attention may improve performance and ameliorate pathology.

Tracking online poker problem gamblers with player account-based gambling data only

The aim was to develop and validate an instrument to track online problem poker gamblers with player account-based gambling data (PABGD). We emailed an invitation to all active poker gamblers on the online gambling service provider Winamax. The 14,261 participants completed the Problem Gambling Severity Index (PGSI). PGSI served as a gold standard to track problem gamblers (i.e., PGSI ≥ 5). We used a stepwise logistic regression to build a predictive model of problem gambling with PABGD, and validated it. Of the sample 18% was composed of online poker problem gamblers. The risk factors of problem gambling included in the predictive model were being male, compulsive, younger than 28 years, making a total deposit > 0 euros, having a mean loss per gambling session > 1.7 euros, losing a total of > 45 euros in the last 30 days, having a total stake > 298 euros, having > 60 gambling sessions in the last 30 days, and multi-tabling. The tracking instrument had a sensitivity of 80%, and a specificity of 50%. The quality of the instrument was good. This study illustrates the feasibility of a method to develop and validate instruments to track online problem gamblers with PABGD only. Copyright © 2016 John Wiley & Sons, Ltd.

Effects of craving behavioral intervention on neural substrates of cue-induced craving in Internet gaming disorder

Internet gaming disorder (IGD) is characterized by high levels of craving for online gaming and related cues. Since addiction-related cues can evoke increased activation in brain areas involved in motivational and reward processing and may engender gaming behaviors or trigger relapse, ameliorating cue-induced craving may be a promising target for interventions for IGD. This study compared neural activation between 40 IGD and 19 healthy control (HC) subjects during an Internet-gaming cue-reactivity task and found that IGD subjects showed stronger activation in multiple brain areas, including the dorsal striatum, brainstem, substantia nigra, and anterior cingulate cortex, but lower activation in the posterior insula. Furthermore, twenty-three IGD subjects (CBI + group) participated in a craving behavioral intervention (CBI) group therapy, whereas the remaining 17 IGD subjects (CBI − group) did not receive any intervention, and all IGD subjects were scanned during similar time intervals. The CBI + group showed decreased IGD severity and cue-induced craving, enhanced activation in the anterior insula and decreased insular connectivity with the lingual gyrus and precuneus after receiving CBI. These findings suggest that CBI is effective in reducing craving and severity in IGD, and it may exert its effects by altering insula activation and its connectivity with regions involved in visual processing and attention bias.

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IGD subjects showed altered cue-induced neural activation in reward-related areas.

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IGD subjects alleviated IGD symptoms after CBI.

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IGD subjects showed higher insular activation after CBI.

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IGD subjects showed lower insula-lingual gyrus/precuneus connectivity after CBI.

Largely overlapping neuronal substrates of reactivity to drug, gambling, food and sexual cues: A comprehensive meta-analysis

Cue reactivity to natural and social rewards is essential for motivational behavior. However, cue reactivity to drug rewards can also elicit craving in addicted subjects. The degree to which drug and natural rewards share neural substrates is not known. The objective of this study is to conduct a comprehensive meta-analysis of neuroimaging studies on drug, gambling and natural stimuli (food and sex) to identify the common and distinct neural substrates of cue reactivity to drug and natural rewards. Neural cue reactivity studies were selected for the meta-analysis by means of activation likelihood estimations, followed by sensitivity and clustering analyses of averaged neuronal response patterns. Data from 176 studies (5573 individuals) suggests largely overlapping neural response patterns towards all tested reward modalities. Common cue reactivity to natural and drug rewards was expressed by bilateral neural responses within anterior cingulate gyrus, insula, caudate head, inferior frontal gyrus, middle frontal gyrus and cerebellum. However, drug cues also generated distinct activation patterns in medial frontal gyrus, middle temporal gyrus, posterior cingulate gyrus, caudate body and putamen. Natural (sexual) reward cues induced unique activation of the pulvinar in thalamus. Neural substrates of cue reactivity to alcohol, drugs of abuse, food, sex and gambling are largely overlapping and comprise a network that processes reward, emotional responses and habit formation. This suggests that cue-mediated craving involves mechanisms that are not exclusive for addictive disorders but rather resemble the intersection of information pathways for processing reward, emotional responses, non-declarative memory and obsessive-compulsive behavior.

Goal Management Training and Mindfulness Meditation improve executive functions and transfer to ecological tasks of daily life in polysubstance users enrolled in therapeutic community treatment

BACKGROUND

We have previously shown that Goal Management Training+Mindfulness Meditation (GMT+MM) improves executive functions in polysubstance users enrolled in outpatient treatment. The aim of this study was to establish if GMT+MM has similar positive effects on executive functions in polysubstance users in residential treatment, and if executive functions' gains transfer to more ecologically valid goal-oriented tasks.

METHODS

Thirty-two polysbustance users were randomly allocated to eight weeks of GMT+MM (n=16) or control, i.e., no-intervention (n=16); both groups received treatment as usual. Outcome measures included performance in laboratory tasks of basic and complex executive functions (i.e., basic: working memory and inhibition; complex: planning and self-regulation) and in an ecological task of goal-directed behavior (the Multiple Errands Test - contextualized version, MET-CV) measured post-interventions.

RESULTS

Results showed that GMT+MM was superior to control in improving basic measures of working memory (Letter-number sequencing; F=4.516, p=0.049) and reflection impulsivity (Information Sampling Test; F=6.217, p=0.018), along with initial thinking times during planning (Zoo Map Test; F=8.143, p=0.008). In addition, GMT+MM was superior to control in improving performance in the MET-CV (task failures; F=8.485, p=0.007).

CONCLUSION

Our findings demonstrate that GMT+MM increases reflective processes and the achievement of goals in daily activities, furthermore ecological test can detects changes easily than laboratory tasks.

Psychological and Neurobiological Correlates of Food Addiction

Food addiction (FA) is loosely defined as hedonic eating behavior involving the consumption of highly palatable foods (ie, foods high in salt, fat, and sugar) in quantities beyond homeostatic energy requirements. FA shares some common symptomology with other pathological eating disorders, such as binge eating. Current theories suggest that FA shares both behavioral similarities and overlapping neural correlates to other substance addictions. Although preliminary, neuroimaging studies in response to food cues and the consumption of highly palatable food in individuals with FA compared to healthy controls have shown differing activation patterns and connectivity in brain reward circuits including regions such as the striatum, amygdala, orbitofrontal cortex, insula, and nucleus accumbens. Additional effects have been noted in the hypothalamus, a brain area responsible for regulating eating behaviors and peripheral satiety networks. FA is highly impacted by impulsivity and mood. Chronic stress can negatively affect hypothalamic-pituitary-adrenal axis functioning, thus influencing eating behavior and increasing desirability of highly palatable foods. Future work will require clearly defining FA as a distinct diagnosis from other eating disorders.

Mindfulness meditation improves emotion regulation and reduces drug abuse

BACKGROUND

The core clinical symptoms of addiction include an enhanced incentive for drug taking (craving), impaired self-control (impulsivity and compulsivity), emotional dysregulation (negative mood) and increased stress reactivity. Symptoms related to impaired self-control involve reduced activity in anterior cingulate cortex (ACC), adjacent prefrontal cortex (mPFC) and other brain areas. Behavioral training such as mindfulness meditation can increase the function of control networks including those leading to improved emotion regulation and thus may be a promising approach for the treatment of addiction.

METHODS

In a series of randomized controlled trials (RCTs), we tested whether increased ACC/mPFC activity is related to better self-control abilities in executive functions, emotion regulation and stress response in healthy and addicted populations. After a brief mindfulness training (Integrative Body-Mind Training, IBMT), we used the Positive and Negative Affect Schedule (PANAS) and Profile of Mood States (POMS) to measure emotion regulation, salivary cortisol for the stress response and fMRI for brain functional and DTI structural changes. Relaxation training was used to serve as an active control.

RESULTS

In both smokers and nonsmokers, improved self-control abilities in emotion regulation and stress reduction were found after training and these changes were related to increased ACC/mPFC activity following training. Compared with nonsmokers, smokers showed reduced ACC/mPFC activity in the self-control network before training, and these deficits were ameliorated after training.

CONCLUSIONS

These results indicate that promoting emotion regulation and improving ACC/mPFC brain activity can help for addiction prevention and treatment.

Mapping Smoking Addiction Using Effective Connectivity Analysis

Prefrontal and parietal cortex, including the default mode network (DMN; medial prefrontal cortex (mPFC), and posterior cingulate cortex, PCC), have been implicated in addiction. Nonetheless, it remains unclear which brain regions play a crucial role in smoking addiction and the relationship among these regions. Since functional connectivity only measures correlations, addiction-related changes in effective connectivity (directed information flow) among these distributed brain regions remain largely unknown. Here we applied spectral dynamic causal modeling (spDCM) to resting state fMRI to characterize changes in effective connectivity among core regions in smoking addiction. Compared to nonsmokers, smokers had reduced effective connectivity from PCC to mPFC and from RIPL to mPFC, a higher self-inhibition within PCC and a reduction in the amplitude of endogenous neuronal fluctuations driving the mPFC. These results indicate that spDCM can differentiate the functional architectures between the two groups, and may provide insight into the brain mechanisms underlying smoking addiction. Our results also suggest that future brain-based prevention and intervention in addiction should consider the amelioration of mPFC-PCC-IPL circuits.

Identification of Treatment Targets in a Genetic Mouse Model of Voluntary Methamphetamine Drinking

Methamphetamine has powerful stimulant and euphoric effects that are experienced as rewarding and encourage use. Methamphetamine addiction is associated with debilitating illnesses, destroyed relationships, child neglect, violence, and crime; but after many years of research, broadly effective medications have not been identified. Individual differences that may impact not only risk for developing a methamphetamine use disorder but also affect treatment response have not been fully considered. Human studies have identified candidate genes that may be relevant, but lack of control over drug history, the common use or coabuse of multiple addictive drugs, and restrictions on the types of data that can be collected in humans are barriers to progress. To overcome some of these issues, a genetic animal model comprised of lines of mice selectively bred for high and low voluntary methamphetamine intake was developed to identify risk and protective alleles for methamphetamine consumption, and identify therapeutic targets. The mu opioid receptor gene was supported as a target for genes within a top-ranked transcription factor network associated with level of methamphetamine intake. In addition, mice that consume high levels of methamphetamine were found to possess a nonfunctional form of the trace amine-associated receptor 1 (TAAR1). The Taar1 gene is within a mouse chromosome 10 quantitative trait locus for methamphetamine consumption, and TAAR1 function determines sensitivity to aversive effects of methamphetamine that may curb intake. The genes, gene interaction partners, and protein products identified in this genetic mouse model represent treatment target candidates for methamphetamine addiction.

Impulsivity, Stimulant Abuse, and Dopamine Receptor Signaling

The nonmedical use of amphetamine-type stimulants is a worldwide problem, with substantial medical and social consequences. Nonetheless, the identification of a pharmacological treatment for amphetamine use disorder remains elusive. Stimulant users exhibit neurochemical evidence of dopamine-system dysfunction as well as impulsive behaviors that may interfere with the success of treatments for their addiction. This review focuses on the potential role of dopaminergic neurotransmission in impulsivity, both in healthy individuals and chronic stimulant users who meet criteria for methamphetamine dependence. Presented are findings related to the potential contributions of signaling through dopamine D1- and D2-type receptors to self-control impulsivity in methamphetamine- dependent users. The information available points to signaling through striatal D2-type dopamine receptors as a potential therapeutic target for stimulant use disorders, but medications that target D2-type dopamine receptors have not been successful in treating stimulant-use disorders, possibly because D2-type receptors are downregulated. Other means to augment D2-type receptor signaling are therefore under consideration, and one promising approach is the addition of exercise training as an adjunct to behavioral treatment for addiction.

Effects of Trace Amine-associated Receptor 1 Agonists on the Expression, Reconsolidation, and Extinction of Cocaine Reward Memory

BACKGROUND

As a modulator of dopaminergic system, trace amine-associated receptor 1 has been shown to play a critical role in regulating the rewarding properties of additive drugs. It has been demonstrated that activation of trace amine-associated receptor 1 decreased the abuse-related behaviors of cocaine in rats. However, the role of trace amine-associated receptor 1 in specific stages of cocaine reward memory is still unclear.

METHODS

Here, using a cocaine-induced conditioned place preference model, we tested the effects of a selective trace amine-associated receptor 1 agonist RO5166017 on the expression, reconsolidation, and extinction of cocaine reward memory.

RESULTS

We found that RO5166017 inhibited the expression but not retention of cocaine-induced conditioned place preference. RO5166017 had no effect on the reconsolidation of cocaine reward memory. Pretreatment with RO5166017 before extinction hindered the formation of extinction long-term memory. RO5166017 did not affect the movement during the conditioned place preference test, indicating the inhibitory effect of RO5166017 on the expression of cocaine-induced conditioned place preference was not caused by locomotion inhibition. Using a cocaine i.v. self-administration model, we found that the combined trace amine-associated receptor 1 partial agonist RO5263397 with extinction had no effect on the following cue- and drug-induced reinstatement of cocaine-seeking behavior. Repeated administration of the trace amine-associated receptor 1 agonist during extinction showed a continually inhibitory effect on the expression of cocaine reward memory both in cocaine-induced conditioned place preference and cocaine self-administration models.

CONCLUSIONS

Taken together, these results indicate that activation of trace amine-associated receptor 1 specifically inhibited the expression of cocaine reward memory. The inhibitory effect of trace amine-associated receptor 1 agonists on cocaine reward memory suggests that trace amine-associated receptor 1 agonists could be a promising agent to prevent cocaine relapse.