Influence of cue exposure on inhibitory control and brain activation in patients with alcohol dependence

Relapse prevention for alcohol use disorders: combined acamprosate and cue exposure therapy as aftercare

AIMS

Many patients with alcohol use disorders are challenged by cravings leading to repeated relapses. Both cue exposure therapy (CET) and acamprosate target alcohol cravings and are often combined (CET + acamprosate). The main aim of this study was to investigate whether aftercare treatment consisting of CET combined with acamprosate is equivalent to (A) CET as monotherapy, (B) aftercare as usual (AAU) as monotherapy or (C) AAU combined with acamprosate.

METHODS

Patients were randomized to receive either CET with urge-specific coping skills (USCS) as aftercare or AAU. Acamprosate prescription data were extracted from patient case records. Alcohol consumption, cravings, and USCS were assessed at pre-aftercare, post-aftercare, and 6-month follow-up.

RESULTS

Overall, patients increased their alcohol consumption during and following aftercare treatment, thereby relapsing despite any treatment. However, CET + acamprosate achieved greater abstinence compared to AAU + acamprosate at follow-up (p=.047). CET + acamprosate also reduced number of drinking days (p=.020) and number of days with excessive drinking (p=.020) at post-aftercare, when compared to AAU monotherapy. CET monotherapy increased sensible drinking at post-aftercare compared to AAU monotherapy (p=.045) and AAU + acamprosate (p=.047). Only CET monotherapy showed improvement in cravings, when compared to AAU at follow-up (mean urge level: p=.032; peak urge level: p=.014).

CONCLUSION

The study showed that CET both as monotherapy and combined with acamprosate was superior to AAU monotherapy and AAU + acamprosate in reducing alcohol consumption. Only CET + acamprosate was capable of reducing alcohol consumption in the longer term, indicating that anti-craving medication may not impede CET from exerting an effect on alcohol consumption. Trial registration: ClinicalTrials.gov ID: NCT02298751 (24/11-2014).

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.

Commercial Advertising of Alcohol: Using Law to Challenge Public Health Regulation

In most countries, the alcohol industry enjoys considerable freedom to market its products. Where government regulation is proposed or enacted, the alcohol industry has often deployed legal arguments and used legal forums to challenge regulation. Governments considering marketing regulation must be cognizant of relevant legal constraints and be prepared to defend their policies against industry legal challenges.

Augmented tendency to act and altered impulse control in alcohol use disorders

Action preparation relies on the operation of control processes that modulate the excitability of the corticospinal tract. On the one hand, excitatory processes prepare the motor system for the forthcoming response; the stronger these influences, the stronger the tendency to act. On the other hand, inhibitory influences allow to suppress inappropriate actions and, more generally, to ensure some sort of impulse control. Because an impairment in these processes could foster inappropriate drinking behavior, the present study aimed at evaluating the motor correlates of such excitatory and inhibitory influences in non-treatment seeking heavy drinkers (HDs) and inpatients suffering from severe alcohol use disorder (SAUDs). Besides, as cue-elicited craving might further alter these processes, we also assessed the impact of an alcohol-related exposure. To do so, 15 healthy controls (HCs), 15 HDs and 15 SAUDs performed a choice reaction time task after having been immersed in a neutral or an alcohol-related environment, using virtual reality videos. Importantly, single-pulse transcranial magnetic stimulation was applied over the left and the right primary motor cortex during the task to elicit motor-evoked potentials in a set of hand muscles allowing us to specifically probe the impact of excitatory and inhibitory processes on motor activity. Our data indicate that excitatory influences are particularly high in both HDs and SAUDs, especially in the dominant hand, an effect that was not observed in HCs. By contrast, inhibitory influences were found to be perfectly normal in HDs, while they were lacking in SAUDs. Furthermore, the alcohol-related exposure enhanced the level of self-reported craving, but this effect only arose in HDs and did not significantly alter the strength of excitatory and inhibitory influences. Overall, although these results have to be taken with caution due to the small sample sizes, this study suggests that enhanced excitatory processes characterize both HDs and SAUDs, while weaker inhibitory influences only concern SAUDs. Hence, an abnormally strong tendency to act could represent a common feature of hazardous drinking, leading individuals to excessive alcohol consumption, whereas deficient impulse control would be a hallmark of more severe forms of AUD, potentially due to the chronic neurotoxic effects of alcohol. Finally, although an alcohol-related exposure does not seem to affect excitatory and inhibitory processes at play during action preparation per se, future works should evaluate changes in corticospinal excitability during the preparation of responses specifically targeting alcohol-related cues.

Converging vulnerability factors for compulsive food and drug use

Highly palatable foods and substance of abuse have intersecting neurobiological, metabolic and behavioral effects relevant for understanding vulnerability to conditions related to food (e.g., obesity, binge eating disorder) and drug (e.g., substance use disorder) misuse. Here, we review data from animal models, clinical populations and epidemiological evidence in behavioral, genetic, pathophysiologic and therapeutic domains. Results suggest that consumption of highly palatable food and drugs of abuse both impact and conversely are regulated by metabolic hormones and metabolic status. Palatable foods high in fat and/or sugar can elicit adaptation in brain reward and withdrawal circuitry akin to substances of abuse. Intake of or withdrawal from palatable food can impact behavioral sensitivity to drugs of abuse and vice versa. A robust literature suggests common substrates and roles for negative reinforcement, negative affect, negative urgency, and impulse control deficits, with both highly palatable foods and substances of abuse. Candidate genetic risk loci shared by obesity and alcohol use disorders have been identified in molecules classically associated with both metabolic and motivational functions. Finally, certain drugs may have overlapping therapeutic potential to treat obesity, diabetes, binge-related eating disorders and substance use disorders. Taken together, data are consistent with the hypotheses that compulsive food and substance use share overlapping, interacting substrates at neurobiological and metabolic levels and that motivated behavior associated with feeding or substance use might constitute vulnerability factors for one another. This article is part of the special issue on 'Vulnerabilities to Substance Abuse'.

Feedback-Related Brain Potentials Indicate the Influence of Craving on Decision-Making in Patients with Alcohol Use Disorder: An Experimental Study

INTRODUCTION

Alcohol craving is a key symptom of alcohol use disorder (AUD) and a significant cause of poor treatment outcome and frequent relapse. Craving is supposed to impair executive functions by modulating reward salience and decision-making.

OBJECTIVE

The present study sought to clarify this modulation by scrutinizing reward feedback processing in an experimental decision-making task, which was accomplished by AUD patients in 2 conditions, in the context of induced alcohol craving and in neutral context.

METHODS

AUD inpatients (N = 40) accomplished the Balloon Analog Risk Task, while their EEG was monitored; counterbalanced across conditions, the tasks were preceded either by craving induction by means of imagery and olfactory alcohol cues, or by neutral cues. Decision choice and variability, and event-related potentials (ERPs) prior to (stimulus-preceding negativity [SPN]) and following (P2a) reward feedback upon decisions, and the outcome-related feedback-related negativity (FRN) were compared between conditions and between patients, who experienced high craving upon alcohol cues (N = 18) and those who did not (N = 22).

RESULTS

Upon craving induction (vs. neutral condition), high-craving AUD patients showed less adjustment of decision choice to preceding reward experience and more variable decisions than low-craving AUD patients, together with accentuated reward-associated ERP (SPN and P2a), while outcome-related FRN was not modified by craving.

CONCLUSIONS

Results support orientation to reward in AUD patients, particularly amplified upon experienced craving, which may interfere with (feedback-guided) decision-making even in alcohol-unrelated context. Craving-accentuated ERP indices suggest neuroadaptive changes of cognitive-motivational states upon chronic alcohol abuse. Together with altered reward-related expectancies, this has to be considered in intervention and relapse prevention.

Impulsivity Derived From the Dark Side: Neurocircuits That Contribute to Negative Urgency

Negative urgency is a unique dimension of impulsivity that involves acting rashly when in extreme distress and impairments in inhibitory control. It has been hypothesized to derive from stress that is related to negative emotional states that are experienced during the withdrawal/negative affect stage of the addiction cycle. Classically, a transition to compulsive drug use prevents or relieves negative emotional states that result from abstinence or stressful environmental circumstances. Recent work suggests that this shift to the "dark side" is also implicated in impulsive use that derives from negative urgency. Stress and anxious, depressed, and irritable mood have high comorbidity with addiction. They may trigger bouts of drug seeking in humans via both negative reinforcement and negative urgency. The neurocircuitry that has been identified in the "dark side" of addiction involves key neuropeptides in the central extended amygdala, including corticotropin-releasing factor. The present review article summarizes empirical and conceptual advances in the field to understand the role of the "dark side" in driving the risky and detrimental substance use that is associated with negative urgency in addiction.

Competing Motivations: Proactive Response Inhibition Toward Addiction-Related Stimuli in Quitting-Motivated Individuals

We examined whether addiction-related cues impact proactive inhibition (the restraint of actions in preparation for stopping) in individuals who are motivated to quit gambling or cannabis use. In Study 1, treatment-seeking individuals with cannabis use disorder and matched controls performed a stop-signal task that required them to inhibit categorizing cannabis or neutral pictures, and within varying levels of stop-signal probability. In Study 2, two groups of individuals, who applied to a voluntary self-exclusion program toward gambling, performed the stop-task following relaxation or gambling craving induction, with results compared to non-gamblers. Study 1 showed that despite being less efficient in proactive inhibition, individuals with cannabis use disorder exhibited heightened proactive inhibition toward cannabis cues. In Study 2, proactive inhibition toward gambling cues was heightened in gamblers after craving, but the degree of proactive adjustment decreased as a function of induced changes in gambling-related motivation. Present findings demonstrate that exposure to addiction-related cues can modulate proactive inhibition in individuals who are motivated to restrict their addictive behaviors.

Neural correlates of correct and failed response inhibition in heavy versus light social drinkers: an fMRI study during a go/no-go task by healthy participants

The ability to suppress responses that are inappropriate, as well as the mechanisms monitoring the accuracy of actions in order to compensate for errors, is central to human behavior. Neural alterations that prevent stopping an inaccurate response, combined with a decreased ability of error monitoring, are considered to be prominent features of alcohol abuse. Moreover, (i) alterations of these processes have been reported in heavy social drinkers (i.e. young healthy individuals who do not yet exhibit a state of alcohol dependence); and (ii) through longitudinal studies, these alterations have been shown to underlie subsequent disinhibition that may lead to future alcohol use disorders. In the present functional magnetic resonance imaging study, using a contextual Go/No-Go task, we investigated whether different neural networks subtended correct inhibitions and monitoring mechanisms of failed inhibitory trials in light versus heavy social drinkers. We show that, although successful inhibition did not lead to significant changes, neural networks involved in error monitoring are different in light versus heavy drinkers. Thus, while light drinkers exhibited activations in their right inferior frontal, right middle cingulate and left superior temporal areas; heavy drinkers exhibited activations in their right cerebellum, left caudate nucleus, left superior occipital region, and left amygdala. These data are functionally interpreted as reflecting a "visually-driven emotional strategy" vs. an "executive-based" neural response to errors in heavy and light drinkers, respectively. Such a difference is interpreted as a key-factor that may subtend the transition from a controlled social heavy consumption to a state of clinical alcohol dependence.

Alcohol-cue exposure decreases response inhibition towards alcohol-related stimuli in detoxified alcohol-dependent patients

The induction of alcohol craving and the cognitive processing of alcohol-related stimuli in alcohol-dependent patients have been reported to compete with inhibitory control and contribute to alcohol relapse. The aim of the present study is to investigate whether the induction of a craving state, using an alcohol cue exposure paradigm, influences response inhibition towards both neutral stimuli and alcohol-related stimuli in alcohol-dependent patients. Thirty-one detoxified alcohol-dependent patients were exposed to either their preferred alcoholic beverage or to a glass of water. They then performed a modified stop signal task, which used alcohol-related words, neutral words and non-words, and a lexical decision as the Go response. The alcohol-cue exposure group reported significantly higher alcohol craving and showed higher percentages of commission errors towards alcohol-related words than the control group. All participants, but especially those of the alcohol-cue exposure group, showed also shorter reaction times when alcohol words were used as targets in go trials. The induction of alcohol craving in detoxified alcohol-dependent patients increases the motivational salience value of alcohol stimuli, leading them to automatically approach alcohol-related cues and therefore impairing response inhibition towards those stimuli.

Alcohol-related and negatively valenced cues increase motor and oculomotor disinhibition in social drinkers

Our aim in the present study was to investigate the psychological mechanisms that underlie the disinhibiting effects of alcohol cues in social drinkers by contrasting motor and oculomotor inhibition after exposure to alcohol-related, emotional, and neutral pictures. We conducted 2 studies in which social drinkers completed modified stop-signal (laboratory) and antisaccade (online) tasks in which positive, negative, alcohol-related, and neutral pictures were embedded. We measured cue-specific disinhibition in each task, and investigated whether sex and drinking status moderated the effects of pictures on disinhibition. Across both studies, comparable increases in disinhibition were observed in response to both alcohol and negatively valenced pictures, relative to both positive and neutral pictures. These differences in disinhibition could not be explained by differences between picture sets in arousal or valence ratings. There was no clear evidence of moderation by sex or drinking status. Secondary analyses demonstrated that alcohol-specific disinhibition was not reliably associated with individual differences in alcohol consumption or craving. These results suggest that the disinhibiting properties of alcohol-related cues cannot be attributed solely to their valence or arousing properties, and that alcohol cues may have unique disinhibiting properties.

Laboratory-induced cue reactivity among individuals with prescription opioid dependence

Prescription opioid (PO) dependence is a critical health problem. Although examination of drug cue reactivity paradigms has advanced the understanding of risk factors for relapse for a variety of substances (e.g., cocaine, alcohol, nicotine), no PO specific drug cue paradigm has been developed. The current study addressed this gap in the literature and evaluated the ability of a newly developed PO drug cue paradigm to elicit subjective, physiological, and neuroendocrine changes among PO-dependent participants (n = 20) as compared to controls (n = 17). The drug cue paradigm included an induction script, viewing and handling paraphernalia (e.g., bottle of oxycontin pills, pill crusher) and watching a video depicting people using POs as well as places related to POs (e.g., pharmacies). Consistent with hypotheses, the PO group demonstrated significant pre- to post-cue increases on subjective ratings of craving, difficulty resisting POs, stress, and anger. The control group did not demonstrate significant changes on any of the subjective measures. Both the PO group and the control group evidenced significant pre- to post-cue increases in physiological responses (e.g., blood pressure, skin conductance), as expected given the arousing nature of the drug cue stimuli. The PO group, but not the control group, evidenced a significant pre- to post-cue increase in heart rate and salivary cortisol levels. The development and validation of a drug cue paradigm for POs may help inform future research and treatment development efforts for patients with PO dependence.

Neurophysiological correlates of response inhibition predict relapse in detoxified alcoholic patients: some preliminary evidence from event-related potentials

BACKGROUND

Alcohol dependence is a chronic relapsing disease. The impairment of response inhibition and alcohol-cue reactivity are the main cognitive mechanisms that trigger relapse. Despite the interaction suggested between the two processes, they have long been investigated as two different lines of research. The present study aimed to investigate the interaction between response inhibition and alcohol-cue reactivity and their potential link with relapse.

MATERIALS AND METHODS

Event-related potentials were recorded during a variant of a "go/no-go" task. Frequent and rare stimuli (to be inhibited) were superimposed on neutral, nonalcohol-related, and alcohol-related contexts. The task was administered following a 3-week detoxification course. Relapse outcome was measured after 3 months, using self-reported abstinence. There were 27 controls (seven females) and 27 patients (seven females), among whom 13 relapsed during the 3-month follow-up period. The no-go N2, no-go P3, and the "difference" wave (P3d) were examined with the aim of linking neural correlates of response inhibition on alcohol-related contexts to the observed relapse rate.

RESULTS

Results showed that 1) at the behavioral level, alcohol-dependent patients made significantly more commission errors than controls (P<0.001), independently of context; 2) through the subtraction no-go P3 minus go P3, this inhibition deficit was neurophysiologically indexed in patients with greater P3d amplitudes (P=0.034); and 3) within the patient group, increased P3d amplitude enabled us to differentiate between future relapsers and nonrelapsers (P=0.026).

CONCLUSION

Our findings suggest that recently detoxified alcoholics are characterized by poorer response-inhibition skills that demand greater neural resources. We propose that event-related potentials can be used in conjunction with behavioral data to predict relapse; this would identify patients that need a higher level of neural resources when suppressing a response is requested.

Impact of alcohol-related video sequences on functional MRI in abstinent alcoholics

The object of this study was the identification of brain areas that were significantly more connected than other regions with a previously identified reference region, the posterior cingulate cortex, during the presentation of visual cues in alcoholics. Alcohol-related and neutral video sequences were presented to 30 alcoholics who had been abstinent for at least 4 days. Participants underwent a psychometric assessment before and after the presentation of the video sequences. Functional MRI data were acquired. Psychophysiological interaction analyses were carried out. Participants reported a significant increase in craving and arousal after the presentation of alcohol-related video sequences. The simple contrast alcohol versus neutral was found not to be significantly different in the present study. The brain regions that were found to correlate significantly more with the posterior cingulate cortex under the alcohol-related condition were the inferior parietal lobe, the medial temporal lobe, the inferior frontal gyrus, the postcentral gyrus, and the precuneus. The involvement of these regions in processes of memory, self-control, and self-reflection with a particular focus on alcohol dependence and craving will be discussed.

Fluctuating disinhibition: implications for the understanding and treatment of alcohol and other substance use disorders

Disinhibition is present in various maladaptive behaviors, including substance use disorders. Most previous research has assumed that disinhibition is a psychological construct that is relatively stable within individuals. However, recent evidence suggests that the ability to inhibit behavior fluctuates in response to environmental and psychological triggers. In this review we discuss some of the factors that cause (dis)inhibition to fluctuate, we examine whether these fluctuations contribute to subjective craving and substance consumption, and we ask if they might increase the risk of relapse in those who are attempting to abstain. The research that we discuss has furthered our understanding of the causal relationships between disinhibition and substance use disorders, and it also highlights opportunities to develop novel treatment interventions. We conclude that substance misusers and their therapists should be made aware of the triggers that can cause disinhibition to fluctuate, and we highlight the need for more research to investigate the effectiveness of inhibitory control training in clinical settings.