Physiological and subjective responding to alcohol cue exposure in alcoholics and control subjects: evidence for appetitive responding

Effects of virtual reality-based cue exposure therapy on craving and physiological responses in alcohol-dependent patients-a randomised controlled trial

BACKGROUND

Cue exposure therapy is used to treat alcohol dependence. However, its effectiveness is controversial due to the limitations of the clinical treatment setting. Virtual reality technology may improve the therapeutic effect. The aim of this study is to explore whether virtual reality-based cue exposure therapy can reduce the psychological craving and physiological responses of patients with alcohol dependence.

METHODS

Forty-four male alcohol-dependent patients were recruited and divided into the study group (n = 23) and the control group (n = 21) according to a random number table. The control group received only conventional clinical treatment for alcohol dependence. The study group received conventional clinical treatment with the addition of VR cue exposure (treatment). The primary outcome was to assess psychological craving and physiological responses to cues of patients before and after treatment.

RESULTS

After virtual reality-based cue exposure therapy, the changes in VAS and heart rate before and after cue exposure in the study group were significantly lower than those in the control group (P < 0.05), while the changes in skin conductance and respiration between the study group and the control group were not significantly different (P > 0.05). The changes in VAS and heart rate before and after cue exposure in the study group were significantly lower than those before treatment (P < 0.05), while the changes in skin conductance and respiration were not significantly different from those before treatment (P > 0.05). The changes in VAS, heart rate, skin conductance and respiration before and after cue exposure in the control group were not significantly different from those before treatment (P > 0.05).

CONCLUSION

Virtual reality-based cue exposure therapy can reduce the psychological craving and part of the physiological responses of alcohol-dependent patients during cue exposure in the short term and may be helpful in the treatment of alcohol dependence.

TRIAL REGISTRATION

The study protocol was registered at the China Clinical Trial Registry on 26/02/2021 ( www.chictr.org.cn ; ChiCTR ID: ChiCTR2100043680).

The impact of age on olfactory alcohol cue-reactivity: A functional magnetic resonance imaging study in adolescent and adult male drinkers

BACKGROUND

Adolescence is marked not only by rapid surges in the prevalence of alcohol use disorders (AUDs) but also by remarkable recovery rates, as most adolescent-onset AUDs naturally resolve over time. Little is known about the differential vulnerability of adolescents and adults. Therefore, this study aimed to unravel the moderating role of age by comparing neural alcohol cue-reactivity, an important AUD biomarker, between low-to-high beer-drinking adolescent (n = 50, 16 to 18 years), and adult (n = 51, 30 to 35 years) males matched on drinking severity.

METHODS

Associations between beer odor-induced brain activity and AUD diagnosis, severity of alcohol use-related problems, recent alcohol use, binge-drinking frequency, and task-induced craving were investigated across and between age groups in regions of interest thought to be central in alcohol cue-reactivity: the medial prefrontal cortex, anterior cingulate cortex, and striatal subregions (nucleus accumbens and caudate putamen). These analyses were complemented by exploratory whole-brain analyses.

RESULTS

Pre-task beer craving increased pre-to-post task in adolescents only. Individual differences in alcohol use, binge drinking, and craving did not relate to beer odor-induced activity. Although region-of-interest analyses did not reach significance, whole-brain analyses showed that adolescents with AUD, compared with adolescents without AUD and adults with AUD, had higher beer odor-induced activity in a large mesocorticolimbic cluster encompassing the right caudate, nucleus accumbens, orbitofrontal cortex, and the olfactory sulcus. Activity in the right caudate and putamen was positively associated with the severity of alcohol use-related problems in adolescents but negatively associated in adults.

CONCLUSION

These findings suggest a differential role of alcohol cue-reactivity in adolescents compared with adults with AUD and highlight the need for further studies investigating the role of age in the fundamental processes underlying the development of and recovery from of AUD.

How laboratory studies of cigarette craving can inform the experimental alcohol craving literature

Interest in alcohol and other drug craving has flourished over the past two decades, and evidence has accumulated showing that craving can be meaningfully linked to both drug use and relapse. Considerable human experimental alcohol craving research since 2000 has focused on craving as a clinical phenomenon. Self-reported craving to drink typically has served as a catch-all for the craving construct in these studies, whereas few studies have considered craving as a process (or hypothetical construct) that interacts with other phenomena to affect use. In contrast to alcohol, we believe that recently there has been more mechanistic work targeting cigarette craving-related processes. Here, we briefly present a narrative review of studies of acute alcohol craving in humans that have been conducted during the past two decades. We then specify important ways in which alcohol and tobacco differ (e.g., the role of withdrawal), and we note the unique challenges in inducing robust alcohol craving states in the laboratory. Finally, we offer recommendations for how the alcohol field might advance its conceptual understanding of craving by adopting ideas and methods drawn from the smoking research literature. Specifically, we suggest that researchers extend their studies to not only examine the link between alcohol craving and relapse but also to focus on why and, in some instances, how alcohol cravings matter clinically, and the circumstances under which craving especially matters. We propose research to investigate the shifts in alcohol-related cognitive and affective processing that occur during alcohol craving states. Furthermore, we highlight the value of research examining the level of insight that individuals with varying levels of alcohol involvement possess about their own craving-related processing shifts. We believe that laboratory studies can provide rich opportunities to examine conceptual questions about alcohol craving that are central to addiction.

Differential effects of quinine adulteration of alcohol on seeking and drinking

Alcohol dependence is characterized by compulsive alcohol use. Alcohol-paired stimuli can drive compulsive alcohol use, induce craving, and lead to relapse. Alcohol dependence is highly heritable, and individuals with a family history are at elevated risk to develop an alcohol use disorder. Understanding the association between genetic vulnerability to alcohol dependence and neural alterations that promote an addiction phenotype are critical to the prevention and treatment of alcohol dependence. Here we use selectively bred alcohol-preferring P rats and their progenitor strain, Wistar rats, to investigate the relationship between genetic liability and alcohol-seeking and drinking behaviors in a discriminative stimuli paradigm. To further investigate strain differences in motivated responding, alcohol was adulterated with quinine, and intake and responding were assessed. While both strains learned to discriminate between stimuli that predicted alcohol availability, P rats learned faster and consumed more alcohol. Quinine adulteration reduced ethanol intake in both strains with no effect on ethanol-seeking measures. These data suggest genetic vulnerability to alcohol dependence is associated with increased motivated behaviors and highlight the utility of P rats in teasing apart the neural mechanisms associated with this phenotype. Additionally, these data suggest a dissociation between the neural systems that engage ethanol drinking versus compulsive ethanol seeking.

Valence processing in the PFC: Reconciling circuit-level and systems-level views

An essential component in animal behavior is the ability to process emotion and dissociate among positive and negative valence in response to a rewarding or aversive stimulus. The medial prefrontal cortex (mPFC)-responsible for higher order executive functions that include cognition, learning, and working memory; and is also involved in sociability-plays a major role in emotional processing and control. Although the amygdala is widely regarded as the "emotional hub," the mPFC encodes for context-specific salience and elicits top-down control over limbic circuitry. The mPFC can then conduct behavioral responses, via cortico-striatal and cortico-brainstem pathways, that correspond to emotional stimuli. Evidence shows that abnormalities within the mPFC lead to sociability deficits, working memory impairments, and drug-seeking behavior that include addiction and compulsive disorders; as well as conditions such as anhedonia. Recent studies investigate the effects of aberrant salience processing on cortical circuitry and neuronal populations associated with these behaviors. In this chapter, we discuss mPFC valence processing, neuroanatomical connections, and physiological substrates involved in mPFC-associated behavior. We review neurocomputational and theoretical models such as "mixed selectivity," that describe cognitive control, attentiveness, and motivational drives. Using this knowledge, we describe the effects of valence imbalances and its influence on mPFC neural pathways that contribute to deficits in social cognition, while understanding the effects in addiction/compulsive behaviors and anhedonia.

Baclofen modulates cardiovascular responses to appetitive cues in treatment-seeking alcohol use disorder individuals

OBJECTIVE

To assess whether baclofen-treated alcohol dependent participants show different subjective and psychophysiological responses to appetitive cues during an alcohol cue reactivity task compared to placebo, and whether these responses are associated with prospective drinking outcomes.

METHODS

Forty-two alcohol dependent participants (placebo: n = 12, low-dose baclofen [30 mg/day] n = 18, high-dose baclofen [75 mg/day]: n = 12) completed an alcohol cue reactivity task, whereby water and alcohol beverage cues were presented, with subsequent recovery periods, and subjective alcohol craving and psychophysiological indices (skin conductance; cardiovascular measures: heart rate, high-frequency heart rate variability) were recorded.

RESULTS

High-dose baclofen-treated participants showed both overall cue reactivity to water and alcohol cues and greater recovery effects during recovery periods, revealed by high-frequency heart rate variability, when compared to low-dose- and placebo-treated participants. There were no medication effects on subjective craving. In high-dose baclofen participants only, there was a predictive effect of lower baseline heart rate variability and fewer post-test percentage of heavy drinking days.

CONCLUSION

There was a dose-specific rescuing effect of high-dose baclofen on the dynamic modulation of cardiovascular responses to eliciting cues. Investigation of treatment responses using psychophysiological techniques may elucidate baclofen's mechanisms of action, and identify subgroups amenable to treatment.

Neuropsychophysiological Measures of Alcohol Dependence: Can We Use EEG in the Clinical Assessment?

Addiction management is complex, and it requires a bio-psycho-social perspective, that ought to consider the multiple etiological and developmental factors. Because of this, a large amount of resources has been allocated to assess the vulnerability to dependence, i.e., to identify the processes underlying the transition from substance use to dependence, as well as its course, in order to determine the key points in its prevention, treatment, and recovery. Consequently, knowledge \from neuroscience must be taken into account, which is why different initiatives have emerged with this objective, such as the "Research Domain Criteria" (RDoC), and the "Addiction Neuroclinical Assessment" (ANA). Particularly, neuropsychophysiological measures could be used as markers of cognitive and behavioral attributes or traits in alcohol dependence, and even trace clinical change. In this way, the aim of this narrative review is to provide an overview following ANA clinical framework, to the most robust findings in neuropsychophysiological changes in alcohol dependence, that underlie the main cognitive domains implicated in addiction: incentive salience, negative emotionality, and executive functioning. The most consistent results have been found in event-related potential (ERP) analysis, especially in the P3 component, that could show a wide clinical utility, mainly for the executive functions. The review also shows the usefulness of other components, implicated in affective and substance-related processing (P1, N1, or the late positive potential LPP), as well as event-related oscillations, such as theta power, with a possible use as vulnerability or clinical marker in alcohol dependence. Finally, new tools emerging from psychophysiology research, based on functional connectivity or brain graph analysis could help toward a better understanding of altered circuits in alcohol dependence, as well as communication efficiency and effort during mental operations. This review concludes with an examination of these tools as possible markers in the clinical field and discusses methodological differences, the need for more replicability studies and incipient lines of work. It also uses consistent findings in psychophysiology to draw possible treatment targets and cognitive profiles in alcohol dependence.

Evidence for incentive salience sensitization as a pathway to alcohol use disorder

The incentive salience sensitization (ISS) theory of addiction holds that addictive behavior stems from the ability of drugs to progressively sensitize the brain circuitry that mediates attribution of incentive salience (IS) to reward-predictive cues and its behavioral manifestations. In this article, we establish the plausibility of ISS as an etiological pathway to alcohol use disorder (AUD). We provide a comprehensive and critical review of evidence for: (1) the ability of alcohol to sensitize the brain circuitry of IS attribution and expression; and (2) attribution of IS to alcohol-predictive cues and its sensitization in humans and non-human animals. We point out gaps in the literature and how these might be addressed. We also highlight how individuals with different alcohol subjective response phenotypes may differ in susceptibility to ISS as a pathway to AUD. Finally, we discuss important implications of this neuropsychological mechanism in AUD for psychological and pharmacological interventions attempting to attenuate alcohol craving and cue reactivity.

COMT Inhibition Alters Cue-Evoked Oscillatory Dynamics during Alcohol Drinking in the Rat

Alterations in the corticostriatal system have been implicated in numerous substance use disorders, including alcohol use disorder (AUD). Adaptations in this neural system are associated with enhanced drug-seeking behaviors following exposure to cues predicting drug availability. Therefore, understanding how potential treatments alter neural activity in this system could lead to more refined and effective approaches for AUD. Local field potentials (LFPs) were acquired simultaneously in the prefrontal cortex (PFC) and nucleus accumbens (NA) of both alcohol preferring (P) and Wistar rats engaged in a Pavlovian conditioning paradigm wherein a light cue signaled the availability of ethanol (EtOH). On test days, the catechol-o-methyl-transferase (COMT) inhibitor tolcapone was administered prior to conditioning. Stimulus-evoked voltage changes were observed following the presentation of the EtOH cue in both strains and were most pronounced in the PFC of P rats. Phase analyses of LFPs in the θ band (5–11 Hz) revealed that PFC-NA synchrony was reduced in P rats relative to Wistars but was robustly increased during drinking. Presentation of the cue resulted in a larger phase reset in the PFC of P rats but not Wistars, an effect that was attenuated by tolcapone. Additionally, tolcapone reduced cued EtOH intake in P rat but not Wistars. These results suggest a link between corticostriatal synchrony and genetic risk for excessive drinking. Moreover, inhibition of COMT within these systems may result in reduced attribution of salience to reward paired stimuli via modulation of stimulus-evoked changes to cortical oscillations in genetically susceptible populations.

Effects of varenicline on alcohol cue reactivity in heavy drinkers

RATIONALE

Clinical trials and human laboratory studies have established that varenicline can reduce rates of alcohol use among heavy drinkers. Less is known about the mechanisms by which varenicline has this effect on drinking behavior. Reactivity to alcohol cues is often cited as the primary cause of relapse among those being treated for alcohol use disorder, and several front-line treatments for alcohol use disorder work, at least in part, by minimizing cue-induced alcohol craving.

OBJECTIVE

The current double-blind, placebo-controlled human laboratory study tested the effects of varenicline on alcohol cue reactivity in a group of heavy-drinking adult smokers and nonsmokers.

METHODS

As part of a larger series of sequential human laboratory experiments testing the effects of varenicline on drinking outcomes, participants were assigned (between-participant) to receive either active varenicline (2 mg/day) or placebo. Following a titration period, participants (n = 77) attended a laboratory session during which they were exposed to alcohol and neutral cues using a standard cue reactivity paradigm.

RESULTS

Alcohol cue exposure increased craving for alcohol in both medication groups. However, participants receiving varenicline showed a smaller increase in alcohol craving compared to participants receiving placebo. The medication effect did not differ between smokers and nonsmokers. Among smokers, alcohol cue exposure also increased tobacco craving. Varenicline did not attenuate this effect.

CONCLUSIONS

Results support the use of varenicline for reducing alcohol use in heavy drinkers and identify a potential mechanism by which varenicline reduces drinking. Varenicline continues to show promise as a pharmacological treatment for alcohol use disorder.

Psychometric evaluation of a Swedish version of the Shortened Desires for Alcohol Questionnaire (Shortened-DAQ)

INTRODUCTION

Craving is a clinically important feature of alcohol use disorders (AUD), representing a diagnostic criterion as well as a target for treatment. The Desire for Alcohol Questionnaire (DAQ) is a widely used scale to measure craving. The aim of the current study was to evaluate the psychometric properties of a Swedish version of the Shortened-DAQ.

METHOD

The English DAQ was translated into Swedish and back translated to English. Individuals with a diagnosis of AUD (n=118) participated in a laboratory experiment comprising presentation of alcohol and non-alcohol cues, as well as consumption of an alcoholic drink, with the aim of exploring changes in the craving responses following pharmacological treatment for AUD. Subjective craving across the experimental conditions was recorded using Shortened-DAQ and a Visual Analogue Scale (VAS). The psychometric analysis of the Shortened-DAQ investigated some important aspects of reliability, validity and the factor solution using principal components analysis.

RESULTS

Cronbach's alphas were above 0.8 across all sessions, the test-retest correlations were statistically significant. In the alcohol cue session the Shortened-DAQ total score was significantly greater compared to the non-alcohol cue session, and correlated significantly with the VAS craving item across all sessions. The principal component analysis resulted in two significant factors comprised of (1) Alcohol desire and reinforcement and (2) Ability to control drinking. No difference in psychometric properties between treatment and placebo groups were found.

CONCLUSION

In future clinical studies on alcohol craving responses in Swedish patients with AUD, we suggest the use of the Swedish Shortened-DAQ, due to its comparably swift administration and overall acceptable psychometric properties.

The sensory features of a food cue influence its ability to act as an incentive stimulus and evoke dopamine release in the nucleus accumbens core

The sensory properties of a reward-paired cue (a conditioned stimulus; CS) may impact the motivational value attributed to the cue, and in turn influence the form of the conditioned response (CR) that develops. A cue with multiple sensory qualities, such as a moving lever-CS, may activate numerous neural pathways that process auditory and visual information, resulting in CRs that vary both within and between individuals. For example, CRs include approach to the lever-CS itself (rats that “sign-track”; ST), approach to the location of reward delivery (rats that “goal-track”; GT), or an “intermediate” combination of these behaviors. We found that the multimodal sensory features of the lever-CS were important to the development and expression of sign-tracking. When the lever-CS was covered, and thus could only be heard moving, STs not only continued to approach the lever location but also started to approach the food cup during the CS period. While still predictive of reward, the auditory component of the lever-CS was a much weaker conditioned reinforcer than the visible lever-CS. This plasticity in behavioral responding observed in STs closely resembled behaviors normally seen in rats classified as “intermediates.” Furthermore, the ability of both the lever-CS and the reward-delivery to evoke dopamine release in the nucleus accumbens was also altered by covering the lever—dopamine signaling in STs resembled neurotransmission observed in rats that normally only GT. These data suggest that while the visible lever-CS was attractive, wanted, and had incentive value for STs, when presented in isolation, the auditory component of the cue was simply predictive of reward, lacking incentive salience. Therefore, the specific sensory features of cues may differentially contribute to responding and ensure behavioral flexibility.

Measures of skin conductance and heart rate in alcoholic men and women during memory performance

We examined abnormalities in physiological responses to emotional stimuli associated with long-term chronic alcoholism. Skin conductance responses (SCR) and heart rate (HR) responses were measured in 32 abstinent alcoholic (ALC) and 30 healthy nonalcoholic (NC) men and women undergoing an emotional memory task in an MRI scanner. The task required participants to remember the identity of two emotionally-valenced faces presented at the onset of each trial during functional magnetic resonance imaging (fMRI) scanning. After viewing the faces, participants saw a distractor image (an alcoholic beverage, nonalcoholic beverage, or scrambled image) followed by a single probe face. The task was to decide whether the probe face matched one of the two encoded faces. Skin conductance measurements (before and after the encoded faces, distractor, and probe) were obtained from electrodes on the index and middle fingers on the left hand. HR measurements (beats per minute before and after the encoded faces, distractor, and probe) were obtained by a pulse oximeter placed on the little finger on the left hand. We expected that, relative to NC participants, the ALC participants would show reduced SCR and HR responses to the face stimuli, and that we would identify greater reactivity to the alcoholic beverage stimuli than to the distractor stimuli unrelated to alcohol. While the beverage type did not differentiate the groups, the ALC group did have reduced skin conductance and HR responses to elements of the task, as compared to the NC group.

Alcoholism risk reduction in France: a modernised approach related to alcohol misuse disorders

During many years in France, risk reduction strategies for substance abuse concerned prevention strategies in the general population or interventions near users of illicit substances. In this spirit, the reduction of consumption only concerned opiate addicts. With regard to alcohol, the prevention messages relative to controlled consumption were difficult to transmit because of the importance of this product in the culture of the country. In addition, methods of treatment of alcoholism rested on the dogma of abstinence. Several factors have recently led to an evolution in the treatment of alcohol use disorders integrating the reduction of consumption in strategies. Strategies for reducing consumption should aim for consumption below recommended thresholds (two drinks per day for women, three for the men) or, at least, in that direction. It must also be supported by pharmacotherapy and psychotherapy, which offer possibilities. Failure to manage reduction will allow the goals to be revisited and to reconsider abstinence. Finally this evolution or revolution is a new paradigm carried in particular by a pragmatic approach of the disease and new treatments. The aims of this article are to give elements of comprehension relating to the evolution of the practices in France in prevention and treatment of alcohol use disorders and in particular with regard to the reduction of consumption.

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.

Sensory modality of smoking cues modulates neural cue reactivity

RATIONALE

Behavioral experiments have demonstrated that the sensory modality of presentation modulates drug cue reactivity.

OBJECTIVES

The present study on nicotine addiction tested whether neural responses to smoking cues are modulated by the sensory modality of stimulus presentation.

METHODS

We measured brain activation using functional magnetic resonance imaging (fMRI) in 15 smokers and 15 nonsmokers while they viewed images of smoking paraphernalia and control objects and while they touched the same objects without seeing them.

RESULTS

Haptically presented, smoking-related stimuli induced more pronounced neural cue reactivity than visual cues in the left dorsal striatum in smokers compared to nonsmokers. The severity of nicotine dependence correlated positively with the preference for haptically explored smoking cues in the left inferior parietal lobule/somatosensory cortex, right fusiform gyrus/inferior temporal cortex/cerebellum, hippocampus/parahippocampal gyrus, posterior cingulate cortex, and supplementary motor area.

CONCLUSIONS

These observations are in line with the hypothesized role of the dorsal striatum for the expression of drug habits and the well-established concept of drug-related automatized schemata, since haptic perception is more closely linked to the corresponding object-specific action pattern than visual perception. Moreover, our findings demonstrate that with the growing severity of nicotine dependence, brain regions involved in object perception, memory, self-processing, and motor control exhibit an increasing preference for haptic over visual smoking cues. This difference was not found for control stimuli. Considering the sensory modality of the presented cues could serve to develop more reliable fMRI-specific biomarkers, more ecologically valid experimental designs, and more effective cue-exposure therapies of addiction.

Neurocircuitry for modeling drug effects

The identification and functional understanding of the neurocircuitry that mediates alcohol and drug effects that are relevant for the development of addictive behavior is a fundamental challenge in addiction research. Here we introduce an assumption-free construction of a neurocircuitry that mediates acute and chronic drug effects on neurotransmitter dynamics that is solely based on rodent neuroanatomy. Two types of data were considered for constructing the neurocircuitry: (1) information on the cytoarchitecture and neurochemical connectivity of each brain region of interest obtained from different neuroanatomical techniques; (2) information on the functional relevance of each region of interest with respect to alcohol and drug effects. We used mathematical data mining and hierarchical clustering methods to achieve the highest standards in the preprocessing of these data. Using this approach, a dynamical network of high molecular and spatial resolution containing 19 brain regions and seven neurotransmitter systems was obtained. Further graph theoretical analysis suggests that the neurocircuitry is connected and cannot be separated into further components. Our analysis also reveals the existence of a principal core subcircuit comprised of nine brain regions: the prefrontal cortex, insular cortex, nucleus accumbens, hypothalamus, amygdala, thalamus, substantia nigra, ventral tegmental area and raphe nuclei. Finally, by means of algebraic criteria for synchronizability of the neurocircuitry, the suitability for in silico modeling of acute and chronic drug effects is indicated. Indeed, we introduced as an example a dynamical system for modeling the effects of acute ethanol administration in rats and obtained an increase in dopamine release in the nucleus accumbens-a hallmark of drug reinforcement-to an extent similar to that seen in numerous microdialysis studies. We conclude that the present neurocircuitry provides a structural and dynamical framework for large-scale mathematical models and will help to predict chronic drug effects on brain function.

Functional neuroimaging studies in addiction: multisensory drug stimuli and neural cue reactivity

Neuroimaging studies on cue reactivity have substantially contributed to the understanding of addiction. In the majority of studies drug cues were presented in the visual modality. However, exposure to conditioned cues in real life occurs often simultaneously in more than one sensory modality. Therefore, multisensory cues should elicit cue reactivity more consistently than unisensory stimuli and increase the ecological validity and the reliability of brain activation measurements. This review includes the data from 44 whole-brain functional neuroimaging studies with a total of 1168 subjects (812 patients and 356 controls). Correlations between neural cue reactivity and clinical covariates such as craving have been reported significantly more often for multisensory than unisensory cues in the motor cortex, insula and posterior cingulate cortex. Thus, multisensory drug cues are particularly effective in revealing brain-behavior relationships in neurocircuits of addiction responsible for motivation, craving awareness and self-related processing.

Effect of the threat of a disulfiram-ethanol reaction on cue reactivity in alcoholics

RATIONALE

Little is known about the effect of disulfiram on subjective and autonomic nervous system cue reactivity in the laboratory. The dissuasive psychological effect manifested as a threat would seem to prevail over the pharmacological effect.

OBJECTIVES

The primary objective was to determine whether there was a difference in cue reactivity responses during a threat condition compared to a neutral condition during alcohol cue exposure.

METHODS

In a crossover randomized study, participants received threat and neutral messages during two cue exposure sessions. The threat condition consisted of leading the patients to believe they had ingested 500 mg of disulfiram and the neutral condition of informing them that they had ingested a placebo, while in both condition they received the same placebo.

RESULTS

Physiological cue reactivity was demonstrated by a decrease in diastolic blood pressure during the threat compared to the neutral condition (p=0.04). Heart rate and subjective cue reactivity measures remained unchanged. There was a negative affect (assessed by the Positive and Negative Affect Scale) by condition by exposure interaction.

CONCLUSIONS

The threat of a disulfiram-ethanol reaction appears to affect cue reactivity physiologically rather than subjectively. While the data does not show changes in subjective ratings, it is possible that there are alternative beneficial effects arising from other cognitive processes that are not captivated by self-reported craving scales, reflected by decreases in negative affect and blood pressure. From this perspective, disulfiram might be recast to be more acceptable to patients.

The effects of acamprosate on alcohol-cue reactivity and alcohol priming in dependent patients: a randomized controlled trial

RATIONALE

Acamprosate is a widely utilized, efficacious treatment for relapse prevention in alcohol-dependent patients; yet, little is known regarding its therapeutic mechanism of action.

OBJECTIVES

The aim of the present study was to examine the effect of acamprosate on cue reactivity and alcohol priming in alcohol-dependent patients.

METHODS

In a double-blind design, 56 treatment seeking patients were randomized to 21 days of either acamprosate or placebo treatment and then participated in a series of cue- and alcohol-priming sessions. Alcohol cues consisted of a mixture of alcohol related visual, tactile, olfactory, and auditory stimuli. Non-alcohol-related cues were contextually similar but had no connection to alcohol. In the alcohol-priming procedure, patients were provided with an alcohol drink of their own choice at a dose corresponding to 0.20 gr. EtOH/kg bodyweight. Subjective, physiological, and biological measurements were recorded before and after each test session. Following study completion, all patients were referred to formal treatment.

RESULTS

The results showed that acamprosate attenuated the subjective craving induced by alcohol priming in comparison to placebo-treated patients. Furthermore, acamprosate reduced alcohol-induced elevation in blood-cortisol levels. Lastly, there was a negative correlation between acamprosate plasma levels and alcohol craving following a priming drink. No effects of acamprosate on cue reactivity, or on the acute rewarding and sedating effects of the priming drink, were observed.

CONCLUSION

These results suggest a potential mechanism by which acamprosate mediates its therapeutic effect in the treatment of alcoholism, by attenuating the urge to drink following an alcohol slip.

Context-induced relapse of conditioned behavioral responding to ethanol cues in rats

BACKGROUND

The environmental context in which drug-conditioned cues are encountered could modulate the capacity of such cues to trigger relapse in abstinent addicts. We explored this hypothesis using a behavioral animal model.

METHODS

Rats were trained to discriminate between two auditory stimuli; the first (CS+) was paired with 10% ethanol and the second (CS-) was presented without ethanol. Training occurred in operant conditioning chambers equipped with distinct contextual stimuli, and entries into the ethanol delivery port during the stimuli were measured. Behavior was then extinguished by presenting both stimuli without ethanol in a second, different context. Context-dependent renewal of port entries was tested by presenting the CS+ and CS- without ethanol in the original training context.

RESULTS

At test, port entries during the CS+ increased compared with extinction levels, while responding during the CS- remained unchanged (n = 11). This effect was attenuated after multiple extinction sessions in three distinct contexts (n = 18), compared with an equivalent number of extinction sessions in a single unique context (n = 16). Context-dependent renewal of port entries was also observed to a CS+ paired with 14% sucrose (n = 7) but not to a CS+ paired with 2% sucrose (n = 8).

CONCLUSIONS

Environmental contexts can trigger the relapse of behavioral responding to ethanol- and sucrose-predictive cues in rats. For ethanol, this effect can be reduced by extinguishing responses to the ethanol cue in multiple distinct contexts, a manipulation that could increase the efficacy of cue-reactivity treatments for addiction.

The genomic determinants of alcohol preference in mice

Searches for the identity of genes that influence the levels of alcohol consumption by humans and other animals have often been driven by presupposition of the importance of particular gene products in determining positively or negatively reinforcing effects of ethanol. We have taken an unbiased approach and performed a meta-analysis across three types of mouse populations to correlate brain gene expression with levels of alcohol intake. Our studies, using filtering procedures based on QTL analysis, produced a list of eight candidate genes with highly heritable expression, which could explain a significant amount of the variance in alcohol preference in mice. Using the Allen Brain Atlas for gene expression, we noted that the candidate genes' expression was localized to the olfactory and limbic areas as well as to the orbitofrontal cortex. Informatics techniques and pathway analysis illustrated the role of the candidate genes in neuronal migration, differentiation, and synaptic remodeling. The importance of olfactory cues, learning and memory formation (Pavlovian conditioning), and cortical executive function, for regulating alcohol intake by animals (including humans), is discussed.

Stress-induced and alcohol cue-induced craving in recently abstinent alcohol-dependent individuals

BACKGROUND

Research has shown that exposure to stress/negative affect and to alcohol cues can each increase alcohol craving and relapse susceptibility in alcohol-dependent individuals. However, whether the emotional and physiological states associated with stress-induced and alcohol cue-induced craving are comparable has not been well studied. Therefore, this study examined the craving, emotional, and physiological responses to stress and to alcohol cues in treatment-engaged, 4-week abstinent, alcohol-dependent individuals using analogous stress and alcohol cue imagery methods.

METHOD

Twenty treatment-seeking, alcohol-dependent participants (18 males/2 females) were exposed to a brief 5-minute guided imagery procedure that involved imagining a recent personal stressful situation, a personal alcohol cue-related situation, and a neutral-relaxing situation, 1 imagery per session presented in random order. Alcohol craving, anxiety and emotion rating scales, cardiovascular measures, and salivary cortisol were compared across the 3 conditions.

RESULTS

Exposure to stress and to alcohol cues each produced significant increases in alcohol craving, anxiety, and negative emotions and decreases in positive emotions. Stress-induced alcohol craving was significantly correlated with increases in sadness, anger, and anxiety ratings, but alcohol cue-induced craving was associated with decreases in positive affect (joy and neutral relaxed state) and increases in anxiety and fear ratings. Furthermore, stress increased systolic and diastolic blood pressure responses, but significant increases in salivary cortisol were only observed in the alcohol cue condition.

CONCLUSIONS

Although both stress and alcohol cues produce increases in anxiety associated with alcohol craving, each produced a dissociable psychobiological state involving subjective emotional, cardiovascular, and cortisol responses. These data could have significant implications for understanding the specific psychobiology associated with stress or alcohol cue exposure and their potential effects on alcohol relapse susceptibility.

Ethanol-associated cues produce general pavlovian-instrumental transfer

BACKGROUND

Conditioned stimuli are thought to play an important role in maintaining ethanol use and inducing relapse. Therefore, understanding the mechanisms through which such stimuli trigger ethanol seeking is of interest in the study and treatment of alcoholism.

METHODS

This series of experiments examined the impact of ethanol-associated cues on ethanol-seeking behavior using a Pavlovian-instrumental transfer design. Rats received Pavlovian training in which an auditory stimulus predicted ethanol (10%) delivery. In a separate instrumental training phase, animals were trained to press a lever for ethanol. In the test phase, the impact of the stimulus on instrumental performance was assessed in extinction by presenting the stimulus while animals were free to perform the lever-press response. Experiment 2 assessed the selectivity of the transfer effect; rats received training with 2 auditory stimuli which predicted either ethanol or sucrose (2%) delivery and were trained to perform 2 instrumental responses, one earning ethanol and the other earning sucrose. Finally, Experiment 3 examined the selectivity of PIT using 2 natural rewards (sucrose and polycose).

RESULTS

The results from Experiment 1 show that ethanol supports excitatory conditioning and that ethanol-associated cues facilitate instrumental performance for ethanol. When the selectivity of the transfer effect was examined in Experiment 2, the ethanol-paired stimulus was found to have a general excitatory effect on reward-seeking behavior, affecting both ethanol-directed and sucrose-directed responding equally. In contrast, the sucrose-paired stimulus had a selective effect, elevating sucrose-directed responding only. Experiment 3 confirms that selective transfer is observed when 2 natural rewards are used to reinforce responding.

CONCLUSIONS

These data provide further evidence that ethanol-associated cues can drive ethanol-seeking behaviors. Because ethanol-associated cues also enhanced seeking behavior for a nonalcohol reward, these results additionally suggest that the modulation of reward-directed behaviors by cues associated with ethanol versus natural rewards may rely on different behavioral and neural mechanisms.