Exposure to the taste of alcohol elicits activation of the mesocorticolimbic neurocircuitry

Brain-based origins of change language: a beginning

Motivational interviewing (MI) is a promising treatment for heavy drinking. Client change talk (CT), a critical component of MI, has been associated with differential brain activation. The goal of this study was to begin to deconstruct how and why CT may affect the brain. Specifically, we sought to determine whether simply repeating statements in favor of change would cause differential brain activation, or whether client statements must be spontaneously generated within a therapeutic milieu in order to influence brain activation. We therefore examined blood oxygenation level dependent (BOLD) response following two types of client language (CT; and sustain talk, ST) across two conditions: (1) Self-Generated: CT and ST were elicited during an MI session vs. (2) Experimenter-Selected: a pre-established list of CT and ST was provided to the individual in the absence of an MI session. Across both conditions, participants' CT and ST were visually and aurally presented during fMRI. We enrolled 39 recent binge drinkers (41% male; M age=19.9; n=18 in Self-Generated group; n=21 in Experimenter-Selected group). We found that both types of client language (CT and ST) elicited greater BOLD activation in the Self-Generated vs. the Experimenter-Selected group in the left inferior frontal gyrus/anterior insula and superior temporal gyri (p≤0.001). These findings indicate that the nature of client language matters. It appears that it is not just the words themselves, but the origin (naturally generated within a therapeutic session) that influences brain-based effects.

Central mechanisms of itch

Itch is a complex sensory and emotional experience. Functional brain imaging studies have been performed to identify brain regions associated with this complex experience, and these studies reported that several brain regions are activated by itch stimuli. The possible roles of these regions in itch perception and difference in cerebral mechanism between healthy subjects and chronic itch patients are discussed in this review article. Additionally, the central itch modulation system and cerebral mechanisms of contagious itch, pleasurable sensation evoked by scratching have also been investigated in previous brain imaging studies. We also discuss how these studies advance our understanding of these mechanisms.

Alcohol sensory processing and its relevance for ingestion

Alcohol possesses complex sensory attributes that are first detected by the body via sensory receptors and afferent fibers that promptly transmit signals to brain areas involved in mediating ingestive motivation, reinforcement, and addictive behavior. Given that the chemosensory cues accompanying alcohol consumption are among the most intimate, consistent, and immediate predictors of alcohol's postabsorptive effects, with experience these stimuli also gain powerful associative incentive value to elicit craving and related physiologic changes, maintenance of ongoing alcohol use, and reinstatement of drug seeking after periods of abstinence. Despite the above, preclinical research has traditionally dichotomized alcohol's taste and postingestive influences as independent regulators of motivation to drink. The present review summarizes current evidence regarding alcohol's ability to directly activate peripheral and central oral chemosensory circuits, relevance for intake of the drug, and provides a framework for moving beyond a dissociation between the sensory and postabsorptive effects of alcohol to understand their neurobiological integration and significance for alcohol addiction.

Transcranial magnetic stimulation: potential treatment for co-occurring alcohol, traumatic brain injury and posttraumatic stress disorders

Alcohol use disorder (AUD), mild traumatic brain injury (mTBI), and posttraumatic stress disorder (PTSD) commonly co-occur (AUD + mTBI + PTSD). These conditions have overlapping symptoms which are, in part, reflective of overlapping neuropathology. These conditions become problematic because their co-occurrence can exacerbate symptoms. Therefore, treatments must be developed that are inclusive to all three conditions. Repetitive transcranial magnetic stimulation (rTMS) is non-invasive and may be an ideal treatment for co-occurring AUD + mTBI + PTSD. There is accumulating evidence on rTMS as a treatment for people with AUD, mTBI, and PTSD each alone. However, there are no published studies to date on rTMS as a treatment for co-occurring AUD + mTBI + PTSD. This review article advances the knowledge base for rTMS as a treatment for AUD + mTBI + PTSD. This review provides background information about these co-occurring conditions as well as rTMS. The existing literature on rTMS as a treatment for people with AUD, TBI, and PTSD each alone is reviewed. Finally, neurobiological findings in support of a theoretical model are discussed to inform TMS as a treatment for co-occurring AUD + mTBI + PTSD. The peer-reviewed literature was identified by targeted literature searches using PubMed and supplemented by cross-referencing the bibliographies of relevant review articles. The existing evidence on rTMS as a treatment for these conditions in isolation, coupled with the overlapping neuropathology and symptomology of these conditions, suggests that rTMS may be well suited for the treatment of these conditions together.

Subjective responses to alcohol in the lab predict neural responses to alcohol cues

OBJECTIVE

Subjective responses to alcohol represent a biologically based, genetically moderated, and clinically informative marker of alcoholism risk; however, the physiology underlying this phenotype remains unclear. This study tested whether subjective responses during alcohol administration predict neural responses to alcohol cues in the scanner and whether these neural responses differ between OPRM1 genotypes.

METHOD

Twenty alcohol-dependent individuals were recruited (10 G-allele carriers; 6 women; Mage = 29.4) for a within-subjects alcohol administration in the laboratory and a functional magnetic resonance imaging session consisting of an alcohol taste cues task. Laboratory assessments of alcohol high, liking, craving, and positive and negative reinforcement during alcohol administration were entered as predictors of neural response to the presentation of alcohol cues versus water cues in the scanner and further tested for OPRM1 genotype moderation (whole-brain cluster-corrected at Z > 1.96, p < .05).

RESULTS

Alcohol craving during alcohol administration predicted less neural activity, whereas alcohol reinforcement predicted greater neural activity to alcohol cues versus water cues in regions including the precuneus, posterior cingulate gyrus, and lingual gyrus. Alcohol high predicted greater neural activity to alcohol cues in regions including the precuneus and anterior cingulate cortex. OPRM1 genotype was found to moderate these relationships. No results were observed for alcohol liking.

CONCLUSIONS

This study provides initial evidence that subjective responses to alcohol, namely craving, high, and the reinforcing properties of alcohol, predict neural markers of alcohol cue reactivity. These results support the validity of laboratory and neuroimaging measures of subjective responses to alcohol and offer an integration of these methods in a sample of alcohol-dependent individuals.

Neuroanatomical circuitry mediating the sensory impact of nicotine in the central nervous system

Direct actions of nicotine in the CNS appear to be essential for its reinforcing properties. However, activation of nicotinic acetylcholine receptors (nAChRs) on afferent sensory nerve fibers is an important component of addiction to, and withdrawal from, cigarette smoking. The aim of the present study was to identify the neuroanatomical substrates activated by the peripheral actions of nicotine and to determine whether these sites overlap brain structures stimulated by direct actions of nicotine. Mouse brains were examined by immunohistochemistry for c-Fos protein after intraperitoneal injection of either nicotine hydrogen tartrate salt (NIC; 30 and 40 μg/kg) or nicotine pyrrolidine methiodide (NIC-PM; 20 and 30 μg/kg). NIC-PM induced c-Fos immunoreactivity (IR) at multiple brain sites. In the brainstem, c-Fos IR was detected in the locus coeruleus, laterodorsal tegmental nucleus, and pedunculotegmental nucleus. In the midbrain, c-Fos IR was observed in areas overlapping the ventral tegmental area (VTA), which includes the paranigral nucleus, parainterfascicular nucleus, parabrachial pigmental area, and rostral VTA. Other structures of the nicotine brain-reward circuitry activated by NIC-PM included the hypothalamus, paraventricular thalamic nucleus, lateral habenular nucleus, hippocampus, amygdala, accumbens nucleus, piriform cortex, angular insular cortex, anterior olfactory nucleus, lateral septal nucleus, bed nucleus of stria terminalis, cingulate and medial prefrontal cortex, olfactory tubercle, and medial and lateral orbital cortex. NIC, acting through central and peripheral nAChRs, produced c-Fos IR in areas that overlapped NIC-PM-induced c-Fos-expressing sites. These neuroanatomical data are the first to demonstrate that the CNS structures that are the direct targets of nicotine are also anatomical substrates for the peripheral sensory impact of nicotine.

Varenicline effects on drinking, craving and neural reward processing among non-treatment-seeking alcohol-dependent individuals

RATIONALE

The α4β2 nicotinic acetylcholine receptor partial agonist varenicline has been reported to reduce drinking among both heavy-drinking smokers and primary alcoholics, and this effect may be related to varenicline-mediated reduction of alcohol craving. Among smokers, varenicline has been reported to modulate cigarette cue-elicited brain activation in several reward-related areas.

OBJECTIVES

This pilot study tested varenicline's effects on drinking, alcohol craving, and alcohol cue-elicited activation of reward-related brain areas among non-treatment-seeking alcohol-dependent individuals.

METHODS

Thirty-five such individuals (mean age = 30, 57 % male, 76 % heavy drinking days in the past month, 15 smokers) were randomized to either varenicline (titrated to 2 mg) or placebo for 14 days, and were administered an alcohol cue reactivity fMRI task on day 14. A priori regions of interest (ROIs) were bilateral and medial orbitofrontal cortex (OFC), right ventral striatum (VS), and medial prefrontal cortex (mPFC).

RESULTS

Despite good medication adherence, varenicline did not reduce heavy drinking days or other drinking parameters. It did, however, increase self-reported control over alcohol-related thoughts and reduced cue-elicited activation bilaterally in the OFC, but not in other brain areas.

CONCLUSIONS

These data indicate that varenicline reduces alcohol craving and some of the neural substrates of alcohol cue reactivity. However, varenicline effects on drinking mediated by cue-elicited brain activation and craving might be best observed among treatment-seekers motivated to reduce their alcohol consumption.

Brain activation in response to craving- and aversion-inducing cues related to alcohol in patients with alcohol dependence

BACKGROUND

Episodes of alcohol consumption produce use-limiting aversive effects as well as use-promoting euphoric effects. The brain regions associated with the reward circuit in patients with alcohol dependence (PAD) show signs of conditioning for alcohol craving. Alternatively, brain structures in the medial temporal region are known to be crucial for aversive conditioning. In this study, we compare differences in patterns of brain activation in response to cues that induce cravings versus aversion in PAD.

METHODS

Thirty-eight PAD and 26 healthy volunteers were administered cue reactivity tasks while undergoing functional magnetic resonance imaging (fMRI) to examine brain response to craving-inducing cues (CIC) and aversion-inducing cues (AIC).

RESULTS

Activation of the right medial frontal gyrus (right orbitofrontal cortex) during CIC was greater in PAD than in healthy volunteers. Participants in the PAD group displayed less activation in the right amygdala and the right middle temporal gyrus during AIC than did the healthy volunteers. Brain reactivity within the right medial frontal gyrus in response to CIC was positively correlated with the scores of PAD on the Korean Alcohol Urge Questionnaire (AUQ-K) and the Michigan Alcohol Screening Test (MAST). Reactivity within the amygdala in response to AIC was negatively correlated with AUQ-K scores among PAD.

CONCLUSION

The dysfunction of the orbitofrontal cortex that results from repeated exposure to alcohol accounts for craving and relapse in PAD. Additionally, PAD seem to be less sensitive to cues related to aversive consequences of alcohol overuse in comparison with healthy individuals.

The association between cue-reactivity in the precuneus and level of dependence on nicotine and alcohol

BACKGROUND

Given numerous reports implicating involvement of the precuneus in cue-reactivity paradigms, the goal of this investigation was to examine the relationship between activation of the precuneus in response to drug cues and measures of subjective craving and severity of dependence in volunteers who were comorbid for alcohol and nicotine abuse.

METHODS

Forty research participants, who all reported heavy drinking and daily smoking, were recruited (15 women; 70% Caucasian; mean age=31.2 years) for a functional magnetic resonance imaging (fMRI) session involving a cigarette video-cues task and an alcohol taste-cues task. Mean precuneus activation from both tasks during cue presentation was subjected to bivariate correlation analyses with indices of dependence severity and subjective craving.

RESULTS

Precuneus activation in the contrast of Cigarette Cues vs. Control Cues was positively correlated with scores on the Fagerström Test of Nicotine Dependence (r=0.389, p=0.016), and activation in the Alcohol Cues vs. Control Cues contrast was positively correlated with Alcohol Dependence Scale scores (r=0.338, p=0.038). No correlations with subjective craving were observed (ps>0.05).

CONCLUSIONS

These findings indicate that the precuneus is involved in cue reactivity for both cigarettes and alcohol, and that this involvement is moderated by severity of drug dependence. The precuneus may be a cortical locus for neuroplastic changes related to drug dependence.

The effect of alcohol consumption on the adolescent brain: A systematic review of MRI and fMRI studies of alcohol-using youth

Background

A large proportion of adolescents drink alcohol, with many engaging in high-risk patterns of consumption, including binge drinking. Here, we systematically review and synthesize the existing empirical literature on how consuming alcohol affects the developing human brain in alcohol-using (AU) youth.

Methods

For this systematic review, we began by conducting a literature search using the PubMED database to identify all available peer-reviewed magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI) studies of AU adolescents (aged 19 and under). All studies were screened against a strict set of criteria designed to constrain the impact of confounding factors, such as co-occurring psychiatric conditions.

Results

Twenty-one studies (10 MRI and 11 fMRI) met the criteria for inclusion. A synthesis of the MRI studies suggested that overall, AU youth showed regional differences in brain structure as compared with non-AU youth, with smaller grey matter volumes and lower white matter integrity in relevant brain areas. In terms of fMRI outcomes, despite equivalent task performance between AU and non-AU youth, AU youth showed a broad pattern of lower task-relevant activation, and greater task-irrelevant activation. In addition, a pattern of gender differences was observed for brain structure and function, with particularly striking effects among AU females.

Conclusions

Alcohol consumption during adolescence was associated with significant differences in structure and function in the developing human brain. However, this is a nascent field, with several limiting factors (including small sample sizes, cross-sectional designs, presence of confounding factors) within many of the reviewed studies, meaning that results should be interpreted in light of the preliminary state of the field. Future longitudinal and large-scale studies are critical to replicate the existing findings, and to provide a more comprehensive and conclusive picture of the effect of alcohol consumption on the developing brain.

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A large proportion of adolescents drink alcohol.

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Studies show how alcohol affects human adolescent brain development.

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This includes a systematic review of MRI and fMRI studies in alcohol-using youth.

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Changes in structure and function are observed in the brain in alcohol-using youth.

Differential reward network functional connectivity in cannabis dependent and non-dependent users

BACKGROUND

Emergent studies show that similar to other substances of abuse, cue-reactivity to cannabis is also associated with neural response in the brain's reward pathway (Filbey et al., 2009). However, the inter-relatedness of brain regions during cue-reactivity in cannabis users remains unknown.

METHODS

In this study, we conducted a series of investigations to determine functional connectivity during cue-reactivity in 71 cannabis users. First, we used psychophysiological interaction (PPI) analysis to examine coherent neural response to cannabis cues. Second, we evaluated whether these patterns of network functional connectivity differentiated dependent and non-dependent users. Finally, as an exploratory analysis, we determined the directionality of these connections via Granger connectivity analyses.

RESULTS

PPI analyses showed reward network functional connectivity with the nucleus accumbens (NAc) seed region during cue exposure. Between-group contrasts found differential effects of dependence status. Dependent users (N=31) had greater functional connectivity with amygdala and anterior cingulate gyrus (ACG) seeds while the non-dependent users (N=24) had greater functional connectivity with the NAc, orbitofrontal cortex (OFC) and hippocampus seeds. Granger analyses showed that hippocampal and ACG activation preceded neural response in reward areas.

CONCLUSIONS

Both PPI and Granger analyses demonstrated strong functional coherence in reward regions during exposure to cannabis cues in current cannabis users. Functional connectivity (but not regional activation) in the reward network differentiated dependent from non-dependent cannabis users. Our findings suggest that repeated cannabis exposure causes observable changes in functional connectivity in the reward network and should be considered in intervention strategies.

Dopamine ups and downs in vulnerability to addictions: a neurodevelopmental model

Addictions are commonly presaged by problems in childhood and adolescence. For many individuals this starts with the early expression of impulsive risk-taking, social gregariousness, and oppositional behaviors. Here we propose that these early diverse manifestations reflect a heightened ability of emotionally salient stimuli to activate dopamine pathways that foster behavioral approach. If substance use is initiated, these at-risk youth can also develop heightened responses to drug-paired cues. Through conditioning and drug-induced sensitization, these effects strengthen and accumulate, leading to responses that exceed those elicited by other rewards. At the same time, cues not paired with drug become associated with comparatively lower dopamine release, accentuating further the difference between drug and non-drug rewards. Together, these enhancing and inhibiting processes steer a pre-existing vulnerability toward a disproportionate concern for drugs and drug-related stimuli. Implications for prevention and treatment are discussed.

The insula: a critical neural substrate for craving and drug seeking under conflict and risk

Drug addiction is characterized by the inability to control drug use when it results in negative consequences or conflicts with more adaptive goals. Our previous work showed that damage to the insula disrupted addiction to cigarette smoking-the first time that the insula was shown to be a critical neural substrate for addiction. Here, we review those findings, as well as more recent studies that corroborate and extend them, demonstrating the role of the insula in (1) incentive motivational processes that drive addictive behavior, (2) control processes that moderate or inhibit addictive behavior, and (3) interoceptive processes that represent bodily states associated with drug use. We then describe a theoretical framework that attempts to integrate these seemingly disparate findings. In this framework, the insula functions in the recall of interoceptive drug effects during craving and drug seeking under specific conditions where drug taking is perceived as risky and/or where there is conflict between drug taking and more adaptive goals. We describe this framework in an evolutionary context and discuss its implications for understanding the mechanisms of behavior change in addiction treatments.

White matter integrity is associated with alcohol cue reactivity in heavy drinkers

Neuroimaging studies have shown that white matter damage accompanies excessive alcohol use, but the functional correlates of alcohol-related white matter disruption remain unknown. This study applied tract-based spatial statistics (TBSS) to diffusion tensor imaging (DTI) data from 332 heavy drinkers (mean age = 31.2 ± 9.4; 31% female) to obtain averaged fractional anisotropy (FA) values of 18 white matter tracts. Statistical analyses examined correlations of FA values with blood-oxygenation-level-dependent (BOLD) response to an alcohol taste cue, measured with functional magnetic resonance imaging (fMRI). FA values of nine white matter tracts (anterior corona radiata, body of corpus callosum, cingulate gyrus, external capsule, fornix, inferior frontooccipital fasciculus, posterior corona radiata, retrolenticular limb of internal capsule, and superior longitudinal fasciculus) were significantly, negatively correlated with BOLD activation in medial frontal gyrus, parahippocampal gyrus, fusiform gyrus, cingulum, thalamus, caudate, putamen, insula, and cerebellum. The inverse relation between white matter integrity and functional activation during the alcohol taste cue provides support for the hypothesis that lower white matter integrity in frontoparietal and corticolimbic networks is a factor in loss of control over alcohol consumption.

The cerebral representation of scratching-induced pleasantness

Itch is an unpleasant sensation with the desire to scratch. Although it is well known that scratching itchy skin is pleasurable, the cerebral mechanisms underlying this phenomenon are poorly understood. We hypothesized that the reward system is associated with scratching-induced pleasantness. To investigate this hypothesis, a functional magnetic resonance imaging study was performed in 16 healthy subjects. Pleasantness was evoked by scratching the wrists where itch stimuli were applied, while scratching the dorsal forearms, far from itch stimuli, did not evoke pleasantness. Interestingly, pleasantness evoked by scratching activated not only the reward system (i.e., the striatum and midbrain) but also key regions of perception (i.e., the primary somatosensory cortex) and awareness of subjective feelings (i.e., the insular cortex), indicating that a broad network is involved in scratching-induced pleasantness. Moreover, although itch was suppressed by scratching, motor-related regions such as the supplementary motor area, premotor cortex, and cerebellum showed significant activation when pleasantness was evoked. This activation could explain why scratching-induced pleasantness potentially reinforces scratching behaviors. This study is the first to identify networks activated by scratching-induced pleasantness. The results of the present study provide important information on the cerebral mechanisms underlying why scratching itchy skin evokes pleasurable feelings that reinforce scratching behaviors.

Pharmacogenetics of addiction therapy

Drug addiction is a serious relapsing disease that has high costs to society and to the individual addicts. Treatment of these addictions is still in its nascency, with only a few examples of successful therapies. Therapeutic response depends upon genetic, biological, social, and environmental components. A role for genetic makeup in the response to treatment has been shown for several addiction pharmacotherapies. For several addiction pharmacotherapies, response to treatment varies based on individual genetic makeup. In this chapter, we discuss the role of genetics in pharmacotherapies, specifically for cocaine, alcohol, and opioid dependences. The elucidation of the role of genetics should aid in the development of new treatments and increase the efficacy of existing treatments.

Relationships between drinking motives and smoking expectancies among daily smokers who are also problem drinkers

OBJECTIVE

There is a high co-occurrence of problem drinking and regular cigarette smoking, and cognitive processes (e.g., motivation to use, expectations about the consequences of use) related to each are positively associated with one another. We explored drinking motives in relation to cognitive-based smoking processes among smokers with problematic drinking. We expected that drinking coping motives would be associated with smoking consequences related to negative reinforcement and negative personal outcomes and inflexibility of smoking behavior; observed effects for coping motives would be unique from shared variance with other motives and incrementally evident beyond the variance accounted for by tobacco-related health problems, smoking rate, negative affectivity, cannabis use, and gender.

METHODS

The sample included 195 individuals recruited into a larger study of smoking cessation treatments (i.e., they were interested in quitting), who were heavy drinkers and smoked daily. Participants were primarily male (n = 122, 63%), fairly young (Mage = 30.3 years; SD = 12.46), and predominantly White/Caucasian (n = 175, 80%). Roughly 57% (n = 111) had at least one comorbid Axis I disorder, the most common being social anxiety (n = 21, 11%) and generalized anxiety disorder (n = 12, 6%).

RESULTS

Coping drinking motives predicted negative smoking consequences, negative reinforcement, and smoking inflexibility. Enhancement drinking motives marginally predicted positive reinforcement. Conformity drinking motives predicted smoking consequences related to appetite/weight control. Social drinking motives predicted negative reinforcement and barriers to cessation and marginally predicted positive reinforcement.

CONCLUSIONS

Theoretical models and clinical activities focused on smoking cessation among problem drinkers may benefit from considering the role of drinking motives, particularly coping-oriented motives, to better understanding cognitive-based smoking processes.

Factors modulating neural reactivity to drug cues in addiction: a survey of human neuroimaging studies

Human neuroimaging studies suggest that neural cue reactivity is strongly associated with indices of drug use, including addiction severity and treatment success. However, little is known about factors that modulate cue reactivity. The goal of this review, in which we survey published fMRI and PET studies on drug cue reactivity in cocaine, alcohol, and tobacco cigarette users, is to highlight major factors that modulate brain reactivity to drug cues. First, we describe cue reactivity paradigms used in neuroimaging research and outline the brain circuits that underlie cue reactivity. We then discuss major factors that have been shown to modulate cue reactivity and review specific evidence as well as outstanding questions related to each factor. Building on previous model-building reviews on the topic, we then outline a simplified model that includes the key modulatory factors and a tentative ranking of their relative impact. We conclude with a discussion of outstanding challenges and future research directions, which can inform future neuroimaging studies as well as the design of treatment and prevention programs.

Pharmacogenetics of OPRM1

Pharmacogenetic research has the potential to explain the variation in treatment efficacy within patient populations. Understanding the interaction between genetic variation and medications may provide a method for matching patients to the most effective therapeutic options and improving overall patient outcomes. The OPRM1 gene has been a target of interest in a large number of pharmacogenetic studies due to its genetic and structural variation, as well as the role of opioid receptors in a variety of disorders. The mu-opioid receptor (MOR), encoded by OPRM1, naturally regulates the analgesic response to pain and also controls the rewarding effects of many drugs of abuse, including opioids, nicotine, and alcohol. Genetic variants in OPRM1, particularly the non-synonymous polymorphism A118G, have been repeatedly associated with the efficacy of treatments for pain and various types of dependence. This review focuses on the current understanding of the pharmacogenetic impact of OPRM1, primarily with regard to the treatment of pain and addiction.

Striatal ups and downs: their roles in vulnerability to addictions in humans

Susceptibility to addictive behaviors has been related to both increases and decreases in striatal function. Both profiles have been reported in humans as well as in animal models. Yet, the mechanisms underlying these opposing effects and the manner in which they relate to the behavioral development and expression of addiction remain unclear. In the present review of human studies, we describe a number of factors that could influence whether striatal hyper- or hypo-function is observed and propose a model that integrates the influence of these opposite responses on the expression of addiction related behaviors. Central to this model is the role played by the presence versus absence of addiction related cues and their ability to regulate responding to abused drugs and other rewards. Striatal function and incentive motivational states are increased in the presence of these cues and decreased in their absence. Alternations between these states might account for the progressive narrowing of interests as addictions develop and point to relevant processes to target in treatment.

Association between nicotine dependence severity, BOLD response to smoking cues, and functional connectivity

Enhanced motivational salience towards smoking cues is a consequence of chronic nicotine use, but the degree to which this value increases beyond that of other appetitive cues is unknown. In addition, it is unclear how connectivity between brain regions influences cue reactivity and how cue reactivity and functional connectivity are related to nicotine dependence severity. This study examined neural responses during the presentation of smoking cues and appetitive control cues, as well as functional connectivity in 116 smokers with a range of nicotine dependence severity. Smoking cues elicited greater response above baseline than food cues in orbitofrontal cortex (OFC) and supplementary motor area (SMA) and less deactivation below baseline in middle frontal gyrus, inferior parietal lobe, and middle temporal gyrus. Psychophysiological interaction (PPI) analysis using right OFC as a seed revealed increased connectivity with somatosensory cortex and lateral inferior parietal lobe during smoking cues compared with food cues. Similarly, a PPI analysis using left insula as a seed showed stronger connectivity with somatosensory cortex, right insula, OFC, and striatum. Finally, relationships with nicotine dependence scores showed enhanced response in insula and dorsal anterior cingulate cortex in the smoking vs food comparison, and increased connectivity between insula and circuits involved in motivated behavior. Combined, these results suggest that smokers engage attentional networks and default mode networks involved in self-referential processing to a greater degree during smoking cues. In addition, individuals with greater nicotine dependence severity show increased engagement of sensorimotor and motor preparation circuits, suggesting increased reliance on habitual behavior.

Beer flavor provokes striatal dopamine release in male drinkers: mediation by family history of alcoholism

Striatal dopamine (DA) is increased by virtually all drugs of abuse, including alcohol. However, drug-associated cues are also known to provoke striatal DA transmission- a phenomenon linked to the motivated behaviors associated with addiction. To our knowledge, no one has tested if alcohol's classically conditioned flavor cues, in the absence of a significant pharmacologic effect, are capable of eliciting striatal DA release in humans. Employing positron emission tomography (PET), we hypothesized that beer's flavor alone can reduce the binding potential (BP) of [(11)C]raclopride (RAC; a reflection of striatal DA release) in the ventral striatum, relative to an appetitive flavor control. Forty-nine men, ranging from social to heavy drinking, mean age 25, with a varied family history of alcoholism underwent two [(11)C]RAC PET scans: one while tasting beer, and one while tasting Gatorade. Relative to the control flavor of Gatorade, beer flavor significantly increased self-reported desire to drink, and reduced [(11)C]RAC BP, indicating that the alcohol-associated flavor cues induced DA release. BP reductions were strongest in subjects with first-degree alcoholic relatives. These results demonstrate that alcohol-conditioned flavor cues can provoke ventral striatal DA release, absent significant pharmacologic effects, and that the response is strongest in subjects with a greater genetic risk for alcoholism. Striatal DA responses to salient alcohol cues may thus be an inherited risk factor for alcoholism.

Genetic variation in the alpha synuclein gene (SNCA) is associated with BOLD response to alcohol cues

OBJECTIVE

Preclinical studies implicate the gene encoding the alpha synuclein protein (SNCA) in the pathophysiology of alcohol dependence and dopamine neuron function. Results from clinical studies are less conclusive. Using neurobiological phenotypes in genetic studies, rather than typical heterogeneous diagnostic categories derived from self-report, may improve reliability across studies. This study aimed to examine whether polymorphisms in the SNCA gene were associated with alcohol taste cue-elicited responses in the brain, one such intermediate phenotype.

METHOD

A total of 326 heavy drinkers who underwent an alcohol taste task during functional magnetic resonance imaging (fMRI) also were genotyped. Analyses focused on two previously identified SNCA variants (rs2583985 and rs356168) as well as 27 other single nucleotide polymorphisms from the Illumina Human1M BeadChip that were used in an exploratory analysis of the whole gene. Neurobiological phenotypes were defined as fMRI blood oxygenation level-dependent (BOLD) responses to alcohol taste cue (vs. a control cue) in seven regions of interest known to be involved in cue processing and rich in dopaminergic axon terminals.

RESULTS

Polymorphisms in the SNCA gene were significantly correlated with BOLD activation. Specifically, the largest effect sizes and significance were seen for rs2583985 in paracingulate and caudate (focused analysis) and for rs1372522 in paracingulate (exploratory analysis). Activation in all regions of interest was correlated with alcohol-dependence severity.

CONCLUSIONS

SNCA genotype was found to be associated with the degree of fMRI BOLD response during exposure to the taste of alcohol versus a control taste. This study also further validates the use of this alcohol taste task as an intermediate phenotype for alcohol-dependence severity.

Initial evidence that OPRM1 genotype moderates ventral and dorsal striatum functional connectivity during alcohol cues

BACKGROUND

Endogenous opioids and striatal dopamine have been implicated in cue-induced alcohol craving and have been hypothesized to play a role in goal-directed, as opposed to habitual, alcohol use. This initial study examines dorsal and ventral striatal functional connectivity during alcohol-cue processing as a function of the A118G single-nucleotide polymorphism of the mu-opioid receptor (OPRM1) gene.

METHODS

Seventeen individuals with alcohol dependence (6 females; 90% Caucasian; mean age = 29.4) underwent blood oxygen level-dependent functional magnetic resonance imaging, while performing an alcohol taste-cues task. Psychophysiological interaction analyses investigated associations of the OPRM1 genotype with ventral and dorsal striatum functional connectivity, using the ventral striatum and the caudate as the seed region, respectively.

RESULTS

Compared to A-allele homozygotes, G-allele carriers of the OPRM1 gene showed (i) greater activation of the insula and orbitofrontal cortex and (ii) stronger negative fronto-striatal functional connectivity for both ventral and dorsal striatal seed regions during processing of alcohol versus water cues.

CONCLUSIONS

These preliminary findings suggest that, relative to A-allele homozygotes, G-allele carriers show unstable frontal regulation over reward and/or habit-driven inputs from the striatum resulting from greater reward sensitivity combined with limited self-control resources.

Disrupted ventromedial prefrontal function, alcohol craving, and subsequent relapse risk

IMPORTANCE

Alcohol dependence is a chronic relapsing illness; stress, alcohol-related cues, and neutral-relaxing states significantly influence craving and relapse risk. However, neural mechanisms underlying the association between these states and alcohol craving and relapse risk remain unclear.

OBJECTIVES

To identify neural correlates associated with alcohol craving and relapse outcomes in 45 treatment-engaged, 4- to 8-week abstinent alcohol-dependent (AD) patients, and to compare brain responses of 30 demographically matched AD patients and 30 healthy control subjects during stress, alcohol, and neutral-relaxing cues.

DESIGN

Functional magnetic resonance imaging study while participants were engaging in brief individualized script-driven imagery trials of stress, alcohol cues, and neutral-relaxing scenarios, and a prospective clinical outcome design to assess alcohol relapse 90 days postdischarge from inpatient treatment in the AD group.

SETTINGS

Inpatient treatment setting in a community mental health center and hospital-based research unit.

PATIENTS

Forty-five recovering AD patients in inpatient treatment for examining relapse, and 30 healthy control subjects demographically matched to 30 AD patients (subgroup of the relapse sample) for group comparisons.

INTERVENTION

Twelve-step recovery-based addiction treatment for the patient group.

MAIN OUTCOMES AND MEASURES

Brain response, alcohol craving, and relapse outcome measures (time to relapse and relapse severity).

RESULTS

Increased ventromedial prefrontal cortex (vmPFC) and anterior cingulate cortex (ACC) activation during neutral-relaxing trials was correlated with high alcohol cue-induced and stress-induced craving in early recovering AD patients (x = 6, y = 43, z = -6; P < .01, whole-brain corrected). This vmPFC/ACC hyperactivity significantly predicted subsequent alcohol relapse, with a hazards ratio greater than 8 for increased relapse risk. Additionally, vmPFC/ACC hyperactivation during neutral trials and reduced activity during stress trials were each predictive of greater days of alcohol used after relapse (P < .01, whole-brain corrected). In contrast, matched control subjects showed the reverse pattern of vmPFC/ACC responses to stress, alcohol cues, and relaxed trials (F = 6.42; P < .01, whole-brain corrected).

CONCLUSIONS AND RELEVANCE

Findings indicate that disrupted vmPFC/ACC function plays a role in jeopardizing recovery from alcoholism and may serve as a neural marker to identify those at risk for alcohol relapse.

Cortical activation of accumbens hyperpolarization-active NMDARs mediates aversion-resistant alcohol intake

Compulsive drinking despite serious adverse medical, social and economic consequences is a characteristic of alcohol use disorders in humans. Although frontal cortical areas have been implicated in alcohol use disorders, little is known about the molecular mechanisms and pathways that sustain aversion-resistant intake. Here, we show that nucleus accumbens core (NAcore) NMDA-type glutamate receptors and medial prefrontal (mPFC) and insula glutamatergic inputs to the NAcore are necessary for aversion-resistant alcohol consumption in rats. Aversion-resistant intake was associated with a new type of NMDA receptor adaptation, in which hyperpolarization-active NMDA receptors were present at mPFC and insula but not amygdalar inputs in the NAcore. Accordingly, inhibition of Grin2c NMDA receptor subunits in the NAcore reduced aversion-resistant alcohol intake. None of these manipulations altered intake when alcohol was not paired with an aversive consequence. Our results identify a mechanism by which hyperpolarization-active NMDA receptors under mPFC- and insula-to-NAcore inputs sustain aversion-resistant alcohol intake.

Dorsomedial and dorsolateral striatum exhibit distinct phasic neuronal activity during alcohol self-administration in rats

The development of alcoholism may involve a shift from goal-directed to habitual drinking. These action control systems are distinct in the dorsal striatum, with the dorsomedial striatum (DMS) important for goal-directed behavior and the dorsolateral striatum (DLS) required for habit formation. Goal-directed behavior can be modeled in rats with a fixed ratio (FR) reinforcement schedule, while a variable interval (VI) schedule promotes habitual behavior (e.g. insensitivity to contingency degradation). Using extracellular recordings from chronically implanted electrodes, we investigated how DMS and DLS neurons encoded lever-press responses and conditioned cues during operant alcohol self-administration in these two models. In rats self-administering 10% alcohol on an FR schedule, the DMS neuronal population showed increased firing at the onset of start-of-session stimuli. During self-administration, the most prominent phasic firing patterns in the DMS occurred at the time of reinforcement and reinforcement-associated cues, while the most prominent phasic activity in the DLS surrounded the lever response. Neural recordings from an additional cohort of rats trained on a VI schedule revealed a similar pattern of results; however, phasic changes in firing were smaller and differences between the medial and lateral dorsal striatum were less marked. In summary, the DMS and DLS exhibited overlapping but specialized phasic firing patterns: DMS excitations were typically time-locked to reinforcement, while DLS excitations were generally associated with lever responses. Furthermore, the regional specificities and magnitudes of phasic firing differed between reinforcement schedules, which may reflect differences in behavioral flexibility, reward expectancy and the action sequences required to procure reinforcement.

Neural effects of positive and negative incentives during marijuana withdrawal

In spite of evidence suggesting two possible mechanisms related to drug-seeking behavior, namely reward-seeking and harm avoidance, much of the addiction literature has focused largely on positive incentivization mechanisms associated with addiction. In this study, we examined the contributing neural mechanisms of avoidance of an aversive state to drug-seeking behavior during marijuana withdrawal. To that end, marijuana users were scanned while performing the monetary incentive delay task in order to assess positive and negative incentive processes. The results showed a group x incentive interaction, such that marijuana users had greater response in areas that underlie reward processes during positive incentives while controls showed greater response in the same areas, but to negative incentives. Furthermore, a negative correlation between withdrawal symptoms and response in the amygdala during negative incentives was found in the marijuana users. These findings suggest that although marijuana users have greater reward sensitivity and less harm avoidance than controls, that attenuated amygdala response, an area that underlies fear and avoidance, was present in marijuana users with greater marijuana withdrawal symptoms. This is concordant with models of drug addiction that involve multiple sources of reinforcement in substance use disorders, and suggests the importance of strategies that focus on respective mechanisms.

Adjunctive aripiprazole therapy with escitalopram in patients with co-morbid major depressive disorder and alcohol dependence: clinical and neuroimaging evidence

The effective treatment of depression has been reported to reduce the severity of alcohol use, potentially reflecting improvements in common brain reward circuits. We hypothesized that augmentation therapy of escitalopram with aripiprazole would improve depressive symptoms as well as reduce craving for alcohol and cue-induced brain activity in patients with co-morbid alcohol dependence and major depressive disorder, compared with treatment with escitalopram alone. Thirty-five subjects with major depressive disorder and alcohol dependence were recruited and randomly assigned into 17 aripiprazole + escitalopram and 18 escitalopram only groups. At baseline and following six weeks of treatment, symptoms of depression, craving for alcohol and brain activity were evaluated. During the six week treatment period, Beck Depression Inventory and clinical global index-severity (CGI-S) scores decreased in both the aripiprazole + escitalopram and escitalopram only groups. In addition, following the treatment period, the Korean alcohol urge questionnaire scores in the aripiprazole + escitalopram group were reduced from 23.3±8.4 to 14.3±4.9, compared with those of the escitalopram group of from 21.6±8.4 to 19.3±7.1 (F=13.1, p<0.01). The activity within the anterior cingulate was increased in response to the presentation of alcohol drinking scenes following treatment in the aripiprazole + escitalopram group. The change of brain activity within the left anterior cingulate gyrus in all patients with co-morbid alcohol dependence and major depressive disorder was negatively correlated with the change in craving for alcohol. These findings suggest that the effects of aripiprazole on anterior cingulate cortex might mediate the successful treatment of alcohol dependence in patients with major depressive disorder.

Accumbens functional connectivity during reward mediates sensation-seeking and alcohol use in high-risk youth

BACKGROUND

Differences in fronto-striatal connectivity in problem substance users have suggested reduced influence of cognitive regions on reward-salience regions. Youth with a family history of alcoholism (FH+) have disrupted ventral striatal processing compared with controls with no familial risk (FH-). As sensation-seeking represents an additional vulnerability factor, we hypothesized that functional connectivity during reward anticipation would differ by family history, and would mediate the relationship between sensation-seeking and drinking in high-risk subjects.

METHODS

Seventy 18-22 year olds (49 FH+/21 FH-) performed a monetary incentive delay task during functional magnetic resonance imaging. Group connectivity differences for incentive (reward/loss) vs. neutral conditions were evaluated with psychophysiological interaction (PPI) analysis, seeded in nucleus accumbens (NAcc). Indirect effects of sensation-seeking on drinking volume through accumbens connectivity were tested.

RESULTS

NAcc connectivity with paracentral lobule/precuneus and sensorimotor areas was decreased for FH- vs. increased for FH+ during incentive anticipation. In FH+, task-related functional coupling between left NAcc and supplementary sensorimotor area (SSMA) and right precuneus correlated positively with sensation-seeking and drinking volume and mediated their relationship. In FH-, left NAcc-SSMA connectivity correlated negatively with sensation-seeking but was not related to drinking.

CONCLUSIONS

These results suggest preexisting differences in accumbens reward-related functional connectivity in high-risk subjects. NAcc coupling with SSMA, involved in attention and motor networks, and precuneus, a default mode structure, appear to mediate sensation-seeking's effect on drinking in those most at-risk. Differences in accumbens connectivity with attention/motor/default networks, rather than control systems, may influence the reward system's role in vulnerability for substance abuse.

Striatocortical pathway dysfunction in addiction and obesity: differences and similarities

Neuroimaging techniques are starting to reveal significant overlap in the brain circuitry underlying addiction and disorders of dyscontrol over rewarding behaviors (such as binge eating disorder and obesity). Positron emission tomography (PET) has demonstrated impaired striatal dopamine (DA) signaling (decreased D2 receptors) in drug addiction and obesity that is associated with reduced baseline glucose metabolism in medial and ventral prefrontal brain regions. Functional magnetic resonance imaging (fMRI) has documented brain activation abnormalities that also implicate DA-modulated striato-cortical pathways. In this review we map findings from recent neuroimaging studies that differentiate brain activation in drug/food addiction from those in controls within brain networks functionally connected with ventral and dorsal striatum. We show that regions found to be abnormal in addiction and obesity frequently emerge at the overlap of the dorsal and the ventral striatal networks. Medial temporal and superior frontal regions functionally connected with dorsal striatum display greater vulnerability in obesity and eating disorders than in drug addictions, indicating more widespread abnormalities for obesity and eating disorders than for addictions. This corroborates involvement of both ventral striatal (predominantly associated with reward and motivation) and dorsal striatal networks (associated with habits or stimulus response learning) in addiction and obesity but also identify distinct patterns between these two disorders.

White Matter and Cognitive Changes in Veterans Diagnosed with Alcoholism and PTSD

Alcoholism frequently occurs in returning U.S. Veterans, and is often comorbid with Post Traumatic Stress Disorder (PTSD). The goal of this study was to investigate the relationship between white matter changes and neuropsychological alterations in Operation Enduring Freedom, and/or Operation Iraqi Freedom (OEF/OIF) alcoholic Veterans with two primary aims: (1) to examine the relationship of alcoholism to brain structure and function while controlling for the potential effects of comorbid PTSD, and (2) to examine whether the effects of alcoholism are moderated by the quantity of lifetime alcohol consumption. Our sample consisted of 71 deployed OEF/OIF Veterans stratified into four groups: alcoholics without PTSD, alcoholics with PTSD, participants with PTSD without comorbid alcoholism, and control participants without alcoholism or PTSD. Participants were given an extensive neuropsychological and psychiatric assessment battery, as well as Magnetic Resonance Diffusion Tensor Imaging (DT-MRI) scans. Results showed that disruption of executive functioning, and abnormal fractional anisotropy (FA; a measure of axonal integrity) within the frontal subcortical and dorsolateral frontal-parietal regions, occurred independently of the effects of PTSD. Furthermore, these cognitive and neuronal alterations were unique to the most severe subgroup of alcoholics who consumed the greatest amount of alcohol over the course of their lifetime, as compared to the rest of the sample. Axonal integrity within this subgroup, in regions underlying the frontal subcortical area, was shown to be decreased independently of cognitive changes. Integrity of axons underlying the dorsolateral frontal-parietal region, however, was increased. We hypothesized that this is a compensatory mechanism for executive dysfunction.

Functional neuroimaging studies of alcohol cue reactivity: a quantitative meta-analysis and systematic review

A comprehensive understanding of the neurobiology of alcohol cue reactivity is critical in identifying the neuropathology of alcohol use disorders (AUD) and developing treatments that may attenuate alcohol craving and reduce relapse risk. Functional neuroimaging studies have identified many brain areas in which alcohol cues elicit activation. However, extant studies have included relatively small numbers of cases, with AUD of varying severity, and have employed many different cue paradigms. We used activation likelihood estimation, a quantitative, coordinate-based meta-analytic method, to analyze the brain areas activated by alcohol-related cues across studies, and to examine whether these areas were differentially activated between cases and controls. Secondarily, we reviewed correlations between behavioral measures and cue-elicited activation, as well as treatment effects on such activation. Data analyzed were from 28 studies of 679 cases and 174 controls. Among cases, alcohol cues elicited robust activation of limbic and prefrontal regions, including ventral striatum, anterior cingulate and ventromedial prefrontal cortex. As compared to controls, cases demonstrated greater activation of parietal and temporal regions, including posterior cingulate, precuneus and superior temporal gyrus. Cue-elicited activation of ventral striatum was most frequently correlated with behavioral measures and most frequently reduced by treatment, but these results were often derived from region-of-interest analyses that interrogated only limbic regions. These findings support long-standing theories of mesolimbic involvement in alcohol cue processing, but suggest that cue-elicited activation of other brain areas may more clearly differentiate cases from controls. Prevention and treatment for AUD should consider interventions that may reduce cue-elicited activation of these areas.

Differential brain response to alcohol cue distractors across stages of alcohol dependence

Altered attention to alcohol-related cues is implicated in the craving and relapse cycle characteristic of alcohol dependence (ALC). Prior cue reactivity studies typically invoke explicit attention to alcohol cues, so the neural response underlying incidental cue exposure remains unclear. Here, we embed infrequent, task-irrelevant alcohol and non-alcohol cues in an attention-demanding task, enabling evaluation of brain responses to distracting alcohol cues. Alcohol dependent individuals, across illness phase (n=44), and controls (n=20) performed a cue-reactivity fMRI target detection task. Significant Group-by-Distractor effects were observed in dorsal anterior cingulate cortex (ACC), inferior parietal lobule, and amygdala. Controls and long-term abstainers increased recruitment of attention and cognitive control regions, while recent and long-term abstainers decreased limbic recruitment to alcohol distractors. Across phases of ALC, self-reported craving positively correlated with cue-related activations in ventral ACC, medial prefrontal cortex, and cerebellum. Results indicate that brain responses elicited by incidental alcohol cues differentiate phases of ALC.

Caudolateral orbitofrontal regional cerebral blood flow is decreased in abstinent cocaine-addicted subjects in two separate cohorts

The orbitofrontal cortex (OFC) is crucial for the inhibition of extraneous stimuli, evaluation of aversive information and emotional regulation-all behaviors impaired in cocaine addiction. Previous studies suggest that cocaine-addicted subjects have decreased basal activity in the OFC. In this study, we examined regional cerebral blood flow (rCBF) during a saline infusion in two independent populations of abstinent cocaine- (and mostly nicotine-) addicted (n=33 and 26) and healthy control (n=35 and 20) men and women. Isolated rCBF decreases (P<0.001) were observed in the left caudolateral OFC, as well as left superior temporal cortex, in cocaine-addicted subjects relative to controls in both cohorts and bilaterally in the combined cohort. An anatomically defined region of the caudolateral OFC showed similar findings and were evident in both male and female addicted subjects. The reliability of these findings across two cohorts reveals a functional disruption in the lateral OFC, a brain region implicated in the evaluation of behavior-terminating stimuli. This may contribute to an addicted individual's persistent drug use despite negative consequences.

Dopaminergic genes modulate response inhibition in alcohol abusing adults

Compulsion in alcohol use disorders (AUD) has been attributed to impairment in response inhibition. Because genes that regulate dopamine (DA) have been implicated not only for risk for AUD but also for impulsivity based on behavioral studies, we set out to examine the underlying neural mechanisms associated with these effects. We collected functional magnetic resonance imaging images on 53 heavy drinking but otherwise healthy adults while performing the Go/NoGo task. We predicted that genetic variants previously reported in the literature to be associated with substance abuse, specifically the DRD2 rs1799732 and DRD4 VNTR, will modulate neural processes underlying response inhibition. Our results showed differential neural response for the DRD4 VNTR during successful inhibition in the inferior frontal gyrus (IFG) (cluster-corrected P<0.05, z=1.9). Similarly, DRD2 rs1799732 groups were significantly different in the precuneus and cingulate gyrus during successful response inhibition (cluster-corrected P<0.05, z=1.9). These findings provide further evidence for the role of DAergic genes in modulating neural response in areas that underlie response inhibition and self-monitoring processes. Variants within these genes appear to influence processes related to impulsive behavior, which may increase one's risk for alcohol abuse and dependence.

Integrating brain and behavior: evaluating adolescents' response to a cannabis intervention

Client language (change talk [CT] and counterchange talk [CCT]) is gaining increasing support as an active ingredient of psychosocial interventions. Preliminary work with adults suggests that there may be a neural basis for this. With a diverse sample of adolescent cannabis users, we evaluated the influence of CT and CCT on blood oxygen level dependent (BOLD) response during an fMRI cannabis cue-exposure paradigm. We also investigated how BOLD activation related to treatment outcomes. Adolescent cannabis users (N = 43; 83.7% male; 53.5% Hispanic; M age = 16 years) were presented with CT and CCT derived from their prescan intervention session during the fMRI paradigm. Additionally, BOLD activation during CT (vs. CCT) was tested as a predictor of 1-month follow-up cannabis use behavior (frequency of cannabis use, cannabis problems, cannabis dependence). We observed a significant interaction, with greater activation during CT (vs. CCT) during the cannabis (but not control) cues in several areas key to self-referential processes (uncorrected p < 0.001; medial frontal gyrus, insula). Furthermore, BOLD activation during CT (vs. CCT) during cannabis (but not control) cues in areas that underlie introspection (posterior cingulate, precuneus) was significantly related to youths' 1-month follow-up cannabis use behavior (frequency of cannabis use, cannabis problems, cannabis dependence; uncorrected p < 0.001). These data indicate a unique interaction pattern, whereby CT (vs. CCT) during the cannabis (but not control) cues was associated with significantly greater activation in brain areas involved in introspection. Further, this activation was related to significantly better treatment outcomes for youth.

Deep brain stimulation surgery for alcohol addiction

BACKGROUND

The consequences of chronic alcohol dependence cause important health and economic burdens worldwide. Relapse rates after standard treatment (medication and psychotherapy) are high. There is evidence from in vivo investigations and from studies in patients that the brain's reward system is critically involved in the development and maintenance of addictive behavior, suggesting that modification of this system could significantly improve the prognosis of addictive patients. Motivated by an accidental observation, we used the nucleus accumbens (NAc), which has a central position in the dopaminergic reward system for deep brain stimulation (DBS) of alcohol addiction.

METHODS

We report our first experiences with NAc DBS for alcohol dependence and review the literature addressing the mechanisms leading to addiction.

RESULTS

Five patients were treated off-label with bilateral NAc DBS for severe alcohol addiction (average follow-up 38 months). All patients experienced significant and ongoing improvement of craving. Two patients remained completely abstinent for more than 4 years. NAc stimulation was tolerated without permanent side effects. Simultaneous recording of local field potentials from the target area and surface electroencephalography while patients performed neuropsychological tasks gave a hint on the pivotal role of the NAc in processing alcohol-related cues.

CONCLUSIONS

To our knowledge, the data presented here reflect the first attempt to treat alcohol-addicted patients with NAc DBS. Electrical NAc stimulation probably counterbalances the effect of drug-related stimuli triggering involuntarily drug-seeking behavior. Meanwhile, two prospective clinical studies using randomized, double-blind, and crossover stimulation protocols for DBS are underway to corroborate these preliminary results.

How acute and chronic alcohol consumption affects brain networks: insights from multimodal neuroimaging

BACKGROUND

Multimodal imaging combining 2 or more techniques is becoming increasingly important because no single imaging approach has the capacity to elucidate all clinically relevant characteristics of a network.

METHODS

This review highlights recent advances in multimodal neuroimaging (i.e., combined use and interpretation of data collected through magnetic resonance imaging [MRI], functional MRI, diffusion tensor imaging, positron emission tomography, magnetoencephalography, MR perfusion, and MR spectroscopy methods) that leads to a more comprehensive understanding of how acute and chronic alcohol consumption affect neural networks underlying cognition, emotion, reward processing, and drinking behavior.

RESULTS

Several innovative investigators have started utilizing multiple imaging approaches within the same individual to better understand how alcohol influences brain systems, both during intoxication and after years of chronic heavy use.

CONCLUSIONS

Their findings can help identify mechanism-based therapeutic and pharmacological treatment options, and they may increase the efficacy and cost effectiveness of such treatments by predicting those at greatest risk for relapse.

fMRI of the brain's response to stimuli experimentally paired with alcohol intoxication

RATIONALE

Individuals learn associations between alcohol's sensory properties and intoxication, with such conditioned stimuli (CS) becoming involved in craving and relapse. However, these CS also carry idiosyncratic associations.

OBJECTIVES

This study aimed to test brain responses to novel CS conditioned with alcohol intoxication.

METHODS

Fourteen heavy drinkers (age 24.9 ± 3.2) performed a reaction time task with embedded novel geometric CS and were told only that the task was to measure alcohol's effect on speed. Rapid intravenous alcohol infusion (the unconditioned stimulus; UCS) began with the appearance of a CS+, using pharmacokinetic modeling to increment breath alcohol by ~18 mg% in 200 s per each of six CS-UCS pairings. Placebo-saline infusion with CS- used the same infusion parameters in same-day randomized/counterbalanced sessions. The next morning subjects, connected to inactive intravenous pumps, underwent functional magnetic resonance imaging (fMRI) of the same task with mixed brief presentations of CS+, CS-, and irrelevant CS and were told that alcohol could be infused at any time during imaging.

RESULTS

CS- responses were significantly greater than those of CS+ in medial frontal cortex. Notably, CS+ responses were negative, suggesting reduced neural activity. Negative activity was most pronounced in early scans, extinguishing with time. As subjects were told that alcohol could be administered in fMRI, a CS+ without alcohol is similar to a negative prediction error, with associated reduced frontal activity during withheld reward.

CONCLUSIONS

Novel stimuli relatively free of demand characteristics can be classically conditioned to intermittent brain exposure of even low alcohol concentrations, permitting imaging studies of conditioned alcohol expectancies.

The role of the Asn40Asp polymorphism of the mu opioid receptor gene (OPRM1) on alcoholism etiology and treatment: a critical review

The endogenous opioid system has been implicated in the pathophysiology of alcoholism as it modulates the neurobehavioral effects of alcohol. A variant in the mu opioid receptor gene (OPRM1), the Asn40Asp polymorphism, has received attention as a functional variant that may influence a host of behavioral phenotypes for alcoholism as well as clinical response to opioid antagonists. This paper will review converging lines of evidence on the effect of the Asn40Asp SNP on alcoholism phenotypes, including: (i) genetic association studies; (ii) behavioral studies of alcoholism; (iii) neuroimaging studies; (iv) pharmacogenetic studies and clinical trials; and (v) preclinical animal studies. Together, these lines of research seek to elucidate the effects of this functional polymorphism on alcoholism etiology and treatment response.

Correlation between Ventromedial Prefrontal Cortex Activation to Food Aromas and Cue-driven Eating: An fMRI Study

Food aromas are signals associated with both food's availability and pleasure. Previous research from this laboratory has shown that food aromas under fasting conditions evoke robust activation of medial prefrontal brain regions thought to reflect reward value (Bragulat, et al. 2010). In the current study, eighteen women (eleven normal-weight and seven obese) underwent a two-day imaging study (one after being fed, one while fasting). All were imaged on a 3T Siemens Trio-Tim scanner while sniffing two food (F; pasta and beef) odors, one non-food (NF; Douglas fir) odor, and an odorless control (CO). Prior to imaging, participants rated hunger and perceived odor qualities, and completed the Dutch Eating Behavior Questionnaire (DEBQ) to assess "Externality" (the extent to which eating is driven by external food cues). Across all participants, both food and non-food odors (compared to CO) elicited large blood oxygenation level dependent (BOLD) responses in olfactory and reward-related areas, including the medial prefrontal and anterior cingulate cortex, bilateral orbitofrontal cortex, and bilateral piriform cortex, amygdala, and hippocampus. However, food odors produced greater activation of medial prefrontal cortex, left lateral orbitofrontal cortex and inferior insula than non-food odors. Moreover, there was a significant correlation between the [F > CO] BOLD response in ventromedial prefrontal cortex and "Externality" sub-scale scores of the DEBQ, but only under the fed condition; no such correlation was present with the [NF > CO] response. This suggests that in those with high Externality, ventromedial prefrontal cortex may inappropriately valuate external food cues in the absence of internal hunger.

Proposed model of the neurobiological mechanisms underlying psychosocial alcohol interventions: the example of motivational interviewing

OBJECTIVE

Despite the prevalence and profound consequences of alcohol use disorders, psychosocial alcohol interventions have widely varying outcomes. The range of behavior following psychosocial alcohol treatment indicates the need to gain a better understanding of active ingredients and how they may operate. Although this is an area of great interest, at this time there is a limited understanding of how in-session behaviors may catalyze changes in the brain and subsequent alcohol use behavior. Thus, in this review, we aim to identify the neurobiological routes through which psychosocial alcohol interventions may lead to post-session behavior change as well as offer an approach to conceptualize and evaluate these translational relationships.

METHOD

PubMed and PsycINFO searches identified studies that successfully integrated functional magnetic resonance imaging and psychosocial interventions.

RESULTS

Based on this research, we identified potential neurobiological substrates through which behavioral alcohol interventions may initiate and sustain behavior change. In addition, we proposed a testable model linking within-session active ingredients to outside-of-session behavior change.

CONCLUSIONS

Through this review, we present a testable translational model. Additionally, we illustrate how the proposed model can help facilitate empirical evaluations of psychotherapeutic factors and their underlying neural mechanisms, both in the context of motivational interviewing and in the treatment of alcohol use disorders.

Dysfunction of the prefrontal cortex in addiction: neuroimaging findings and clinical implications

The loss of control over drug intake that occurs in addiction was initially believed to result from disruption of subcortical reward circuits. However, imaging studies in addictive behaviours have identified a key involvement of the prefrontal cortex (PFC) both through its regulation of limbic reward regions and its involvement in higher-order executive function (for example, self-control, salience attribution and awareness). This Review focuses on functional neuroimaging studies conducted in the past decade that have expanded our understanding of the involvement of the PFC in drug addiction. Disruption of the PFC in addiction underlies not only compulsive drug taking but also accounts for the disadvantageous behaviours that are associated with addiction and the erosion of free will.

The neural basis of drug stimulus processing and craving: an activation likelihood estimation meta-analysis

BACKGROUND

The capacity of drug cues to elicit drug-seeking behavior is believed to play a fundamental role in drug dependence; yet the neurofunctional basis of human drug cue-reactivity is not fully understood. We performed a meta-analysis to identify brain regions that are consistently activated by presentation of drug cues. Studies involving treatment-seeking and nontreatment-seeking substance users were contrasted to determine whether there were consistent differences in the neural response to drug cues between these populations. Finally, to assess the neural basis of craving, consistency across studies in brain regions that show correlated activation with craving was assessed.

METHODS

Appropriate studies, assessing the effect of drug-related cues or manipulations of drug craving in drug-user populations across the whole brain, were obtained via the PubMed database and literature search. Activation likelihood estimation, a method of quantitative meta-analysis that estimates convergence across experiments by modeling the spatial uncertainty of neuroimaging data, was used to identify consistent regions of activation.

RESULTS

Cue-related activation was observed in the ventral striatum (across both subgroups), amygdala (in the treatment-seeking subgroup and overall), and orbitofrontal cortex (in the nontreatment-seeking subgroup and overall) but not insula cortex. Although a different pattern of frontal and temporal lobe activation between the subgroups was observed, these differences were not significant. Finally, right amygdala and left middle frontal gyrus activity were positively associated with craving.

CONCLUSIONS

These results substantiate the key neural substrates underlying reactivity to drug cues and drug craving.

Subjective responses to alcohol: a paradigm shift may be brewing

BACKGROUND

The meta-analysis by Quinn and Fromme (2011) is reviewed and integrated into the larger field. Guidelines for future research are presented.

RESULTS

With results of the meta-analysis along with those of a recent comprehensive prospective study by our group (King et al., 2011), there is a call to the field to specify terms and integrate theoretical frameworks to advance our knowledge and improve comparisons across trials.

CONCLUSIONS

The meta-analysis is both timely and thorough and will provide clinical researchers with important information to move the field forward.