Identifying the neural circuitry of alcohol craving and relapse vulnerability

Associative memory in alcohol-related contexts: An fMRI study with young binge drinkers

BACKGROUND

Alcohol-related cues are known to influence craving levels, a hallmark of alcohol misuse. Binge drinking (BD), a pattern of heavy alcohol use, has been associated with cognitive and neurofunctional alterations, including alcohol attentional bias, memory impairments, as well as disrupted activity in prefrontal- and reward-related regions. However, literature is yet to explore how memories associated with alcohol-related cues are processed by BDs, and how the recall of this information may influence their reward processing.

AIMS

The present functional magnetic resonance imaging (fMRI) study aimed to investigate the neurofunctional signatures of BD during an associative memory task.

METHOD

In all, 36 university students, 20 BDs and 16 alcohol abstainers, were asked to memorize neutral objects paired with either alcohol or non-alcohol-related contexts. Subsequently, neutral stimuli were presented, and participants were asked to classify them as being previously paired with alcohol- or non-alcohol-related contexts.

RESULTS

While behavioral performance was similar in both groups, during the recall of alcohol-related cues, BDs showed increased brain activation in two clusters including the thalamus, globus pallidus and dorsal striatum, and cerebellum and occipital fusiform gyrus, respectively.

CONCLUSION

These findings suggest that BDs display augmented brain activity in areas responsible for mental imagery and reward processing when trying to recall alcohol-related cues, which might ultimately contribute to alcohol craving, even without being directly exposed to an alcohol-related context. These results highlight the importance of considering how alcohol-related contexts may influence alcohol-seeking behavior and, consequently, the maintenance or increase in alcohol use.

Preconception ethanol exposure changes anxiety, depressive and checking-like behavior and alter the expression levels of MAO-B in male offspring

Alcohol use, which alters the epigenome, increases the probability that it could affect subsequent generations, even if they were never directly exposed to ethanol or even in utero. We explored the effects of parental ethanol exposure before conception on behavioral changes in the offspring. Considering the role of Monoamine oxidase-B (MAO-B) in dopamine turnover in the prefrontal cortex (PFC) and its influence on behavior, and taking into account that ethanol exposure could alter MAO-B, we assessed the protein levels in the offspring. Male and female rats were exposed to ethanol for 30 days and then allowed ten days of abstinence. Afterward, they were mated with either control or ethanol-exposed rats. The F1 and F2 male offspring underwent tests to assess behavioral changes. Additionally, the levels of MAO-B in the PFC were evaluated. Results revealed that in the F1, anxiety increased only in the bi-parental ethanol-exposed male offspring in the elevated plus maze test (p < 0.05), while depressive-like behavior rose only in maternal and bi-parental ethanol-exposed offspring (p < 0.01). However, compulsive-like behavior increased in all ethanol-exposed offspring (p < 0.01). No significant phenotypic changes were observed in the F2. The levels of MAO-B in the PFC increased in the maternal (p < 0.05) and bi-parental ethanol-exposed offspring (p < 0.01). Our study demonstrates that parental ethanol exposure, even in the days preceding mating, adversely affects behaviors and induces molecular changes in the brain. Given these findings, it becomes imperative to monitor children exposed to parental (especially maternal) ethanol for the prevention of mental disorders.

Altered individual gray matter structural covariance networks in early abstinence patients with alcohol dependence

While alterations in cortical thickness have been widely observed in individuals with alcohol dependence, knowledge about cortical thickness-based structural covariance networks is limited. This study aimed to explore the topological disorganization of structural covariance networks based on cortical thickness at the single-subject level among patients with alcohol dependence. Structural imaging data were obtained from 61 patients with alcohol dependence during early abstinence and 59 healthy controls. The single-subject structural covariance networks were constructed based on cortical thickness data from 68 brain regions and were analyzed using graph theory. The relationships between network architecture and clinical characteristics were further investigated using partial correlation analysis. In the structural covariance networks, both patients with alcohol dependence and healthy controls displayed small-world topology. However, compared to controls, alcohol-dependent individuals exhibited significantly altered global network properties characterized by greater normalized shortest path length, greater shortest path length, and lower global efficiency. Patients exhibited lower degree centrality and nodal efficiency, primarily in the right precuneus. Additionally, scores on the Alcohol Use Disorder Identification Test were negatively correlated with the degree centrality and nodal efficiency of the left middle temporal gyrus. The results of this correlation analysis did not survive after multiple comparisons in the exploratory analysis. Our findings may reveal alterations in the topological organization of gray matter networks in alcoholism patients, which may contribute to understanding the mechanisms of alcohol addiction from a network perspective.

Abstinence and Fear Experienced during This Period Produce Distinct Cortical and Hippocampal Adaptations in Alcohol-Dependent Rats

Previous studies demonstrate that ethanol dependence induced by repeating cycles of chronic intermittent ethanol vapor exposure (CIE) followed by protracted abstinence produces significant gray matter damage via myelin dysfunction in the rodent medial prefrontal cortex (mPFC) and alterations in neuronal excitability in the mPFC and the dentate gyrus (DG) of the hippocampus. Specifically, abstinence-induced neuroadaptations have been associated with persistent elevated relapse to drinking. The current study evaluated the effects of forced abstinence for 1 day (d), 7 d, 21 d, and 42 d following seven weeks of CIE on synaptic plasticity proteins in the mPFC and DG. Immunoblotting revealed reduced expression of CaMKII in the mPFC and enhanced expression of GABAA and CaMKII in the DG at the 21 d time point, and the expression of the ratio of GluN2A/2B subunits did not change at any of the time points studied. Furthermore, cognitive performance via Pavlovian trace fear conditioning (TFC) was evaluated in 3 d abstinent rats, as this time point is associated with negative affect. In addition, the expression of the ratio of GluN2A/2B subunits and a 3D structural analysis of neurons in the mPFC and DG were evaluated in 3 d abstinent rats. Behavioral analysis revealed faster acquisition of fear responses and reduced retrieval of fear memories in CIE rats compared to controls. TFC produced hyperplasticity of pyramidal neurons in the mPFC under control conditions and this effect was not evident or blunted in abstinent rats. Neurons in the DG were unaltered. TFC enhanced the GluN2A/2B ratio in the mPFC and reduced the ratio in the DG and was not altered by abstinence. These findings indicate that forced abstinence from CIE produces distinct and divergent alterations in plasticity proteins in the mPFC and DG. Fear learning-induced changes in structural plasticity and proteins contributing to it were more profound in the mPFC during forced abstinence.

Sex differences in alcohol's effects on fronto-amygdalar functional connectivity during processing of emotional stimuli

BACKGROUND

Amygdala function underlying emotion processing has been shown to vary with an individuals' biological sex. Expanding upon functional magnetic resonance imaging (fMRI) findings reported previously where a low level of response was the focus, we examined alcohol and sex effects on functional connectivity between the amygdala and other brain regions. The central hypothesis predicted that sex would influence alcohol's effects on frontal-limbic functional circuits underlying the processing of negative and positive facial emotions.

METHODS

Secondary analyses were conducted on data from a double-blind, placebo controlled, within-subjects, cross-over study in 54 sex-matched pairs (N = 108) of 18- to 25-year-old individuals without an alcohol use disorder at baseline. Participants performed an emotional faces fMRI processing task after placebo or approximately 0.7 mL/kg of ethanol. Psychophysiological interaction analyses examined functional connectivity between the amygdala with other brain regions.

RESULTS

There were significant alcohol-by-sex interactions when processing negatively valenced faces. Whereas intoxicated men exhibited decreased functional connectivity between the amygdala and ventral and dorsal anterior cingulate, angular gyrus, and middle frontal gyrus connectivity was increased in intoxicated women. There was also a main sex effect where women exhibited less functional connectivity in the middle insula than men regardless of whether they received alcohol or placebo. For happy faces, main effects of both sex and alcohol were observed. Women exhibited less amygdala functional connectivity in the right inferior frontal gyrus than men. Both men and women exhibited greater functional connectivity in the superior frontal gyrus in response to alcohol than placebo.

CONCLUSIONS

Alcohol's effects on amygdala functional circuits that underlying emotional processing vary by sex. Women had higher functional connectivity than men following exposure to a moderate dose of alcohol which could indicate that women are better than men at processing affectively laden stimuli when intoxicated.

Multi-modal neuroimaging reveals differences in alcohol-cue reactivity but not neurometabolite concentrations in adolescents who drink alcohol

BACKGROUND

The objective of this multi-modal neuroimaging study was to identify neuroscience-informed treatment targets for adolescent alcohol use disorder (AUD) by examining potential neural alterations associated with adolescent alcohol use.

METHODS

Adolescents (ages 17-19) who heavily used (n=49) or did not use alcohol (n=22) were recruited for a multi-modal neuroimaging protocol, including proton magnetic resonance spectroscopy within the dorsal anterior cingulate cortex (dACC) and an fMRI alcohol cue-reactivity task. The alcohol cue-reactivity task was analyzed across 11 a priori regions-of-interest (ROI), including the dACC, and in an exploratory whole-brain approach. Correlations were run between neurometabolite levels and alcohol cue-reactivity in the dACC.

RESULTS

There were no significant group differences in absolute neurometabolite concentrations. Compared to the control group, the alcohol-using group exhibited heightened alcohol cue reactivity in the left amygdala ROI (p=0.04). The whole-brain approach identified higher alcohol cue reactivity in the alcohol-using group compared to controls in the amygdala and occipital regions, and lower reactivity in the parietal lobe. Whole-brain sex effects were noted, with females displaying higher reactivity regardless of group. No significant correlations were found between neurometabolite levels and alcohol cue-reactivity in the dACC.

CONCLUSIONS

The null neurometabolic findings may be due to age, relatively low severity of alcohol use, and non-treatment-seeking status of the participants. Females showed overall higher reactivity to alcohol cues, indicating a sex effect regardless of alcohol use history. Higher amygdala reactivity in alcohol-using adolescents suggests that emotional processing related to alcohol cues may be a useful target for future adolescent AUD interventions.

Cue-exposure treatment influences resting-state functional connectivity-a randomized controlled fMRI study in alcohol use disorder

RATIONALE

Cue-exposure therapy (CET) consists of exposing patients to the cause of their affliction in a controlled environment and after psychological preparation. Ever since it was conceived, it has been suggested as a treatment for different types of behavioural impairments, from anxiety disorders to substance abuse. In the field of addictive behaviour, many different findings have been shown regarding the effectiveness of this therapy.

OBJECTIVES

This study aims to examine the underlying neurobiological mechanisms of the effects of CET in patients with alcohol use disorder using resting-state functional magnetic resonance imaging (rs-fMRI).

METHODS

In a randomized, controlled study, we examined patients after inpatient detoxification as well as healthy controls. Patients underwent nine sessions of CET spaced over 3 weeks. Rs-fMRI was conducted before treatment and 3 weeks after treatment onset in patients, healthy controls received only one rs-fMRI measurement. The final participant sample with complete data included 35 patients in the CET group, 17 patients in the treatment-as-usual group, and 43 HCs.

RESULTS

Our results show differences in the Salience Network when comparing the CET group to the treatment-as-usual group (TAU). Functional connectivity between the anterior cingulate Cortex (ACC) and the insula was increased after CET, whereas it was decreased from ACC to the putamen and globus pallidus. Further, increased connectivity with the precuneus was found in the dorsal attention network after cue exposure treatment.

CONCLUSIONS

These findings suggest that cue exposure therapy changes the resting-state brain connectivity with additional effects to the standard psychotherapy treatment. Hence, our study results suggest why including CET in standard therapies might improve the preparation of patients in front of daily situations.

Evaluation of 6 years of eHealth data in the alcohol use disorder field indicates improved efficacy of care

Background

Predictive eHealth tools will change the field of medicine, however long-term data is scarce. Here, we report findings on data collected over 6 years with an AI-based eHealth system for supporting the treatment of alcohol use disorder.

Methods

Since the deployment of Previct Alcohol, structured data has been archived in a data warehouse, currently comprising 505,641 patient days. The frequencies of relapse and caregiver-patient messaging over time was studied. The effects of both introducing an AI-driven relapse prediction tool and the COVID-19 pandemic were analyzed.

Results

The relapse frequency per patient day among Previct Alcohol users was 0.28 in 2016, 0.22 in 2020 and 0.25 in 2022 with no drastic change during COVID-19. When a relapse was predicted, the actual occurrence of relapse in the days immediately after was found to be above average. Additionally, there was a noticeable increase in caregiver interactions following these predictions. When caregivers were not informed of these predictions, the risk of relapse was found to be higher compared to when the prediction tool was actively being used. The prediction tool decreased the relapse risk by 9% for relapses that were of short duration and by 18% for relapses that lasted more than 3 days.

Conclusions

The eHealth system Previct Alcohol allows for high resolution measurements, enabling precise identifications of relapse patterns and follow up on individual and population-based alcohol use disorder treatment. eHealth relapse prediction aids the caregiver to act timely, which reduces, delays, and shortens relapses.

The Impact of Alcohol-Induced Epigenetic Modifications in the Treatment of Alcohol use Disorders

Alcohol use disorders are responsible for 5.9% of all death annually and 5.1% of the global disease burden. It has been suggested that alcohol abuse can modify gene expression through epigenetic processes, namely DNA and histone methylation, histone acetylation, and microRNA expression. The alcohol influence on epigenetic mechanisms leads to molecular adaptation of a wide number of brain circuits, including the hypothalamus-hypophysis-adrenal axis, the prefrontal cortex, the mesolimbic-dopamine pathways and the endogenous opioid pathways. Epigenetic regulation represents an important level of alcohol-induced molecular adaptation in the brain. It has been demonstrated that acute and chronic alcohol exposure can induce opposite modifications in epigenetic mechanisms: acute alcohol exposure increases histone acetylation, decreases histone methylation and inhibits DNA methyltransferase activity, while chronic alcohol exposure induces hypermethylation of DNA. Some studies investigated the chromatin status during the withdrawal period and the craving period and showed that craving was associated with low methylation status, while the withdrawal period was associated with elevated activity of histone deacetylase and decreased histone acetylation. Given the effects exerted by ethanol consumption on epigenetic mechanisms, chromatin structure modifiers, such as histone deacetylase inhibitors and DNA methyltransferase inhibitors, might represent a new potential strategy to treat alcohol use disorder. Further investigations on molecular modifications induced by ethanol might be helpful to develop new therapies for alcoholism and drug addiction targeting epigenetic processes.

People who binge drink show neuroendocrine tolerance to alcohol cues that is associated with immediate and future drinking- results from a randomized clinical experiment

Neuroendocrine tolerance to alcohol, i.e., a blunted cortisol response to alcohol, has been linked to Ventromedial Prefrontal Cortex (VmPFC) alcohol cue reactivity and relapse risk in severe Alcohol Use Disorders (AUDs), but its role in the development of AUDs is not clear. Recent work suggests that blunted cortisol responses to alcohol cues in individuals who engage in binge drinking (BD) may play a role in motivation to consume larger amounts of alcohol, but the link between this dysregulated endocrine response and BD's neural responses to alcohol cues remains unclear. To examine this, two groups of participants were recruited based on their recent drinking history. Thirty-three BD and 31 non-binging, social drinkers (SD) were exposed to alcohol cues and water cues in two separate 7 T functional magnetic resonance imaging (fMRI) scans. Each scan was followed by the Alcohol Taste Test (ATT) of implicit motivation for alcohol and a post-experiment, one-month prospective measurement of their "real world" drinking behavior. During each scan session, blood plasma was collected repeatedly to examine the separate effects of alcohol cues and alcohol consumption on cortisol levels. Relative to water cues and SD, BD demonstrated blunted cortisol cue reactivity that was negatively associated with VmPFC cue reactivity. In BD, both blunted cortisol and greater VmPFC cue reactivity were related to immediate and future alcohol consumption in the month following the scans. Thus, neuroendocrine tolerance in BD may be associated with increased incentive salience of cues and contribute mechanistically to increased alcohol consumption seen in the development of AUDs.

GABAergic signaling in alcohol use disorder and withdrawal: pathological involvement and therapeutic potential

Alcohol is one of the most widely used substances. Alcohol use accounts for 5.1% of the global disease burden, contributes substantially to societal and economic costs, and leads to approximately 3 million global deaths yearly. Alcohol use disorder (AUD) includes various drinking behavior patterns that lead to short-term or long-lasting effects on health. Ethanol, the main psychoactive molecule acting in alcoholic beverages, directly impacts the GABAergic system, contributing to GABAergic dysregulations that vary depending on the intensity and duration of alcohol consumption. A small number of interventions have been developed that target the GABAergic system, but there are promising future therapeutic avenues to explore. This review provides an overview of the impact of alcohol on the GABAergic system, the current interventions available for AUD that target the GABAergic system, and the novel interventions being explored that in the future could be included among first-line therapies for the treatment of AUD.

Novel paradigms for the gut-brain axis during alcohol withdrawal, withdrawal-associated depression, and craving in patients with alcohol use disorder

Introduction

Patients with alcohol use disorder (AUD) exhibit symptoms such as alcohol withdrawal, depression, and cravings. The gut-immune response may play a significant role in manifesting these specific symptoms associated with AUD. This study examined the role of gut dysfunction, proinflammatory cytokines, and hormones in characterizing AUD symptoms.

Methods

Forty-eight AUD patients [men (n = 34) and women (n = 14)] aged 23-63 years were grouped using the Clinical Institute Withdrawal Assessment of Alcohol Scale (CIWA) as clinically significant (CS-CIWA [score > 10] [n = 22]) and a clinically not-significant group (NCS-CIWA [score ≤ 10] [n = 26]). Clinical data (CIWA, 90-day timeline followback [TLFB90], and lifetime drinking history [LTDH]) and blood samples (for testing proinflammatory cytokines, hormones, and markers of intestinal permeability) were analyzed. A subset of 16 AUD patients was assessed upon admission for their craving tendencies related to drug-seeking behavior using the Penn-Alcohol Craving Score (PACS).

Results

CS-CIWA group patients exhibited unique and significantly higher levels of adiponectin and interleukin (IL)-6 compared to NCS-CIWA. In the CS group, there were significant and high effects of association for the withdrawal score with gut-immune markers (lipopolysaccharide [LPS], adiponectin, IL-6, and IL-8) and for withdrawal-associated depression with gut-immune markers (scored using MADRS with LPS, soluble cells of differentiation type 14 [sCD14], IL-6, and IL-8). Craving (assessed by PACS, the Penn-Alcohol Craving Scale) was significantly characterized by what could be described as gut dysregulation (LBP [lipopolysaccharide binding protein] and leptin) and candidate proinflammatory (IL-1β and TNF-α) markers. Such a pathway model describes the heavy drinking phenotype, HDD90 (heavy drinking days past 90 days), with even higher effects (R2 = 0.955, p = 0.006) in the AUD patients, who had higher ratings for cravings (PACS > 5).

Discussion

The interaction of gut dysfunction cytokines involved in both inflammation and mediating activity constitutes a novel pathophysiological gut-brain axis for withdrawal symptoms and withdrawal-associated depression and craving symptoms in AUD. AUD patients with reported cravings show a significant characterization of the gut-brain axis response to heavy drinking.

Trial registration

ClinicalTrials.gov, identifier: NCT# 00106106.

Associations of thalamocortical networks with reduced mindfulness in alcohol use disorder

Background

Increased mindfulness is associated with reduced alcohol consumption in patients with alcohol use disorder (AUD) after residential treatment. However, the underlying neurobiological mechanism of mindfulness in AUD is unclear. Therefore, we investigate the structural and functional alterations of the thalamocortical system with a focus on the mediodorsal thalamic nucleus (MD-TN), the default mode and the salience network (DMN/SN) which has previously been associated with mindfulness in healthy subjects. We hypothesized lower mindfulness and reduced structural and functional connectivity (FC) of the thalamocortical system, particularly in the DMN/SN in AUD. We assumed that identified neurobiological alterations in AUD are associated with impairments of mindfulness.

Methods

Forty-five abstinent patients with AUD during residential treatment and 20 healthy controls (HC) were recruited. Structural and resting-state functional MRI-scans were acquired. We analysed levels of mindfulness, thalamic volumes and network centrality degree of the MD-TN using multivariate statistics. Using seed-based whole brain analyses we investigated functional connectivity (FC) of the MD-TN. We performed exploratory correlational analyses of structural and functional DMN/SN measurements with levels of mindfulness.

Results

In AUD we found significantly lower levels of mindfulness, lower bilateral thalamic and left MD-TN volumes, reduced FC between MD-TN and anterior cingulum/insula and lower network centrality degree of the left MD-TN as compared to HC. In AUD, lower mindfulness was associated with various reductions of structural and functional aspects of the MD-TN.

Conclusion

Our results suggest that structural and functional alterations of a network including the MD-TN and the DMN/SN underlies disturbed mindfulness in AUD.

Modifying Pavlovian-to-instrumental transfer by approach avoidance training in healthy subjects: a proof of concept study

The modulation of instrumental action by conditioned Pavlovian cues is hypothesized to play a role in the emergence and maintenance of maladaptive behavior. The Pavlovian to Instrumental transfer task (PIT) is designed to examine the magnitude of the influence of cues on behavior and we aim to manipulate the motivational value of Pavlovian cues to reduce their effect on instrumental responding. To this end, we utilized a joystick-based modification of approach and avoidance propensities that has shown success in clinical populations. To examine changes in PIT, we subjected 35 healthy participants to a series of experimental procedures: (1) Instrumental training was followed by (2) Pavlovian conditioning of neutral stimuli that were associated with monetary reward or loss. (3) In a subsequent joystick task, approach and avoidance tendencies toward conditioned cues were assessed. (4) In a transfer test, the PIT effect as the impact of conditioned cues on instrumental behavior was measured. (5) The explicit knowledge of cue-reward contingencies was assessed in a forced-choice phase. (6, 7) systematic joystick training was followed by a posttest (8) the transfer task and forced-choice test were repeated. We found no effect of training on approach-avoidance propensities in the context of this proof of concept study. A higher response rate towards negative stimuli during PIT after systematic training compared to sham training was seen. On the other hand, we saw an increased PIT effect after sham training. These results contribute to the understanding of the strength of the influence of cues on instrumental behavior. Our findings further stress the importance of context, instructions and operationalization of instrumental behavior in the framework of transfer effects.

Reward Processing in Alcohol-Dependent Patients and First-Degree Relatives: Functional Brain Activity During Anticipation of Monetary Gains and Losses

BACKGROUND

According to the reward deficiency syndrome and allostatic hypotheses, hyposensitivity of mesocorticolimbic regions to non-alcohol-related stimuli predisposes to dependence or is long-lastingly enhanced by chronic substance use. To date, no study has directly compared mesocorticolimbic brain activity during non-drug reward anticipation between alcohol-dependent, at risk, and healthy subjects.

METHODS

Seventy-five abstinent alcohol-dependent human subjects (mean abstinence duration 957.66 days), 62 healthy first-degree relatives of alcohol-dependent individuals, and 76 healthy control subjects without family history of alcohol dependence performed a monetary incentive delay task. Functional magnetic resonance imaging data of the anticipation phase were analyzed, during which visual cues predicted that fast response to a target would result in monetary gain, avoidance of monetary loss, or a neutral outcome.

RESULTS

During gain anticipation, there were no significant group differences. During loss anticipation, abstinent alcohol-dependent subjects showed lower activity in the left anterior insula compared with healthy control subjects without family history of alcohol dependence only (Montreal Neurological Institute [MNI] -25 19 -5; t₂₀₆ = 4.17, familywise error corrected p = .009). However, this effect was no longer significant when age was included as a covariate. There were no group differences between abstinent alcohol-dependent subjects and healthy first-degree relatives or between healthy first-degree relatives and healthy control subjects during loss anticipation, respectively.

CONCLUSIONS

Neither the neural reward deficiency syndrome nor the allostatic hypotheses are supported by the results. Future studies should investigate whether the incentive salience hypothesis allows for more accurate predictions regarding mesocorticolimbic brain activity of subjects with alcohol dependence and healthy individuals during reward and loss anticipation and further examine the neural substrates underlying a predisposition to dependence.

Global brain c-Fos profiling reveals major functional brain networks rearrangements after alcohol reexposure

Many fundamental questions on alcohol use disorder (AUD) are frequently difficult to address by examining a single brain structure, but should be viewed from the whole brain perspective. c-Fos is a marker of neuronal activation. Global brain c-Fos profiling in rodents represents a promising platform to study brain functional networks rearrangements in AUD. We used a mouse model of alcohol drinking in IntelliCage. We trained mice to voluntarily drink alcohol, next subjected them to withdrawal and alcohol reexposure. We have developed a dedicated image computational workflow to identify c-Fos-positive cells in three-dimensional images obtained after whole-brain optical clearing and imaging in the light-sheet microscope. We provide a complete list of 169 brain structures with annotated c-Fos expression. We analyzed functional networks, brain modularity and engram index. Brain c-Fos levels in animals reexposed to alcohol were different from both control and binge drinking animals. Structures involved in reward processing, decision making and characteristic for addictive behaviors, such as precommissural nucleus, nucleus Raphe, parts of colliculus and tecta stood out particularly. Alcohol reexposure leads to a massive change of brain modularity including a formation of numerous smaller functional modules grouping structures involved in addiction development. Binge drinking can lead to substantial functional remodeling in the brain. We provide a list of structures that can be used as a target in pharmacotherapy but also point to the networks and modules that can hold therapeutic potential demonstrated by a clinical trial in patients.

The Dopamine System in Mediating Alcohol Effects in Humans

Brain-imaging studies show that the development and maintenance of alcohol use disorder (AUD) is determined by a complex interaction of different neurotransmitter systems and multiple psychological factors. In this context, the dopaminergic reinforcement system appears to be of fundamental importance. We focus on the excitatory and depressant effects of acute versus chronic alcohol intake and its impact on dopaminergic neurotransmission. Furthermore, we describe alterations in dopaminergic neurotransmission as associated with symptoms of alcohol dependence. We specifically focus on neuroadaptations to chronic alcohol consumption and their effect on central processing of alcohol-associated and reward-related stimuli. Altered reward processing, complex conditioning processes, impaired reinforcement learning, and increased salience attribution to alcohol-associated stimuli enable alcohol cues to drive alcohol seeking and consumption. Finally, we will discuss how the neurobiological and neurochemical mechanisms of alcohol-associated alterations in reward processing and learning can interact with stress, cognition, and emotion processing.

Caudate gray matter volumes and risk of relapse in Type A alcohol-dependent patients: A 7-year MRI follow-up study

BACKGROUND

Whether alteration in regional brain volumes can be detected in Type A alcoholics both at baseline and after a long follow-up remains to be confirmed. Therefore, we examined volume alterations at baseline, and longitudinal changes in a small follow-up subsample.

METHODS

In total of 26 patients and 24 healthy controls were assessed at baseline using magnetic resonance imaging and voxel-based morphometry, among which 17 patients and 6 controls were re-evaluated 7 years later. At baseline, regional cerebral volumes of patients were compared to controls. At follow-up, three groups were compared: abstainers (n = 11, more than 2 years of abstinence), relapsers (n = 6, <2 years of abstinence), and controls (n = 6).

RESULTS

The cross-sectional analyses detected, at both times, higher caudate nuclei volumes bilaterally in relapsers compared to abstainers. In abstainers, the longitudinal analysis indicated recovery of normal gray matter volumes in the middle and inferior frontal gyrus, and in the middle cingulate, while white matter volumes recovery was detected in the corpus callosum and in anterior and superior white matter specific regions.

CONCLUSIONS

Overall, the present investigation revealed larger caudate nuclei in the relapser AUD patient group both at baseline and at follow-up in the cross-sectional analyses. This finding suggest that a higher caudate volume could be a candidate risk factor of relapse. In patients with specific type A alcohol-dependence, we showed that long-term recovery in fronto-striato-limbic GM and WM volumes occurs during long-term abstinence. These results support the crucial role of frontal circuitry in AUD.

Neural Correlates of Cue Reactivity and the Regulation of Craving in Substance Use Disorders

Abstract. Theoretical background: Considerable progress has been made in illuminating the neural basis of the compulsive use patterns characterizing substance use disorders. It has been suggested to utilize these findings to alleviate the health burden associated with substance use. Objective: We address how neuroimaging research can provide these benefits. Methods: Based on neurobiological models of addiction, we highlight neuroimaging research elucidating neural predictors of relapse and how treatments modify these markers. Results: With the focus on cue reactivity, brain activity related to the motivational salience of drugs and automatized use behaviors can predict relapse. Cue reactivity changes with abstinence, and it remains to be determined whether such changes confer periods of critical relapse susceptibility. Conclusions: Several established and emerging interventions modulate brain activity associated with drug value. However, executive deficits in addiction may compromise interventions targeting control-related prefrontal brain areas. Lastly, it remains more difficult to change the brain responses mediating habitual behaviors.

Using Imagination to Integrate Contextual Effects in a Cue-Reactivity Paradigm in Patients with Alcohol Use Disorder: A Functional Magnetic Resonance Imaging Pilot Study

INTRODUCTION

In individuals with alcohol use disorder (AUD), the brain areas underlying cue-induced reactions (e.g., cingulum, striatum, thalamus) and altered activation of these regions have been identified by functional neuroimaging. Neuronal responses to a complex alcohol-related context are yet to investigate. To better understand contextual effects as well as the interplay of cue-induced neural reactions and context exposure, the present study implemented an imagination procedure during functional magnetic resonance imaging (fMRI).

METHODS

Thirteen patients with AUD and 13 healthy controls completed two rounds of a cue-reactivity paradigm inside an MRI scanner. Two individualized imagination tasks were conducted before each of the two cue reactivity tasks. A 2 (group) × 2 (imagination) × 2 (picture-type) analysis of variance (ANOVA) was performed.

RESULTS

The ANOVA revealed a main effect for imagination with higher activation in bilateral thalamus and right caudate nucleus and an interaction effect between imagination and group in right thalamus and left caudate nucleus, due to the patient group reacting stronger during alcohol-related imagination. These structures are involved in relaying sensory information and habit learning. No main or interaction effects of picture type were observed.

CONCLUSIONS

These results support the view that context effects alter the neural responses in thalamus and nucleus caudatus in patients with AUD, and that imagination tasks are suited to incorporate contextual influences in neurophysiological research designs. Future research needs to investigate whether the failure to observe a picture-type effect was due to limited statistical power and omission to individualize picture set, or whether an imagination procedure interferes with the evocation of picture-type effects.

Purpose in life, neural alcohol cue reactivity and daily alcohol use in social drinkers

BACKGROUND AND AIM

Alcohol craving is an urge to consume alcohol that commonly precedes drinking; however, craving does not lead to drinking for all people under all circumstances. The current study measured the correlation between neural reactivity and alcohol cues as a risk, and purpose in daily life as a protective factor that may influence the link between alcohol craving and the subsequent amount of consumption.

DESIGN

Observational study that correlated functional magnetic resonance imaging (fMRI) data on neural cue reactivity and ecological momentary assessments (EMA) on purpose in life and alcohol use.

SETTING

Two college campuses in the United States.

PARTICIPANTS

A total of 54 college students (37 women, 16 men, and 1 other) recruited via campus-based groups from January 2019 to October 2020.

MEASUREMENTS

Participants underwent fMRI while viewing images of alcohol; we examined activity within the ventral striatum, a key region of interest implicated in reward and craving. Participants then completed 28 days of EMA and answered questions about daily levels of purpose in life and alcohol use, including how much they craved and consumed alcohol.

FINDINGS

A significant three-way interaction indicated that greater alcohol cue reactivity within the ventral striatum was associated with heavier alcohol use following craving in daily life only when people were previously feeling a lower than usual sense of purpose. By contrast, individuals with heightened neural alcohol cue reactivity drank less in response to craving if they were feeling a stronger than their usual sense of purpose in the preceding moments (b_interaction  = -0.086, P < 0.001, 95% CI = -0.137, -0.035).

CONCLUSIONS

Neural sensitivity to alcohol cues within the ventral striatum appears to be a potential risk for increased alcohol use in social drinkers, when people feel less purposeful. Enhancing daily levels of purpose in life may promote alcohol moderation among social drinkers who show relatively higher reactivity to alcohol cues.

Learning from addiction: Craving of prescription opioids in chronic pain sufferers

Prescription opioids are a primary driver of opioid-related deaths. Although craving is a substantial component of OUD, the degree to which craving leads to misuse among chronic pain patients on long-term prescription opioids is unknown. A clear understanding of the factors that lead to misuse in this vulnerable population is needed for the development of safe and effective practices for opioid taper. This narrative review summarizes the relevant literature on the role of craving in addiction and chronic pain through epidemiological and behavioral studies. The first part of this review examines the role of craving in predicting opioid use/misuse in individuals with chronic pain with and without OUD. The second part covers methods on how craving is evaluated experimentally using both subjective and objective measures and provides related findings. The overall goal of this review is to facilitate the development of a population-specific description of craving in those who use opioids to control chronic pain and to describe how it may be mechanistically linked to patterns of opioid (mis)use.

Non-invasive neuromodulation of dorsolateral prefrontal cortex to reduce craving in alcohol use disorder: A meta-analysis

Introduction

While several pharmacological and behavioral treatments are available for alcohol use disorder (AUD), they may not be effective for all patients. The aim of this systematic review and meta-analysis was to evaluate the efficacy and safety of rTMS and tDCS for craving in AUD.

Methods

EMBASE, Cochrane Library, PsycINFO, and PubMed databases were searched for original, peer-reviewed research articles in the English language published between January 2000 and January 2022. Randomized controlled trials (RCTs) reporting changes in alcohol craving among patients with AUD were selected. Random-effects meta-analysis was employed to pool data.

Results

Changes in alcohol craving were extracted from 15 RCTs. Six studies assessed the efficacy of rTMS while nine studies examined tDCS. Results demonstrated that in comparison to sham stimulation, active rTMS to the DLPFC yields small but significant reductions in alcohol craving (standardized mean difference [SMD] = -0.27, p = .03). However, DLPFC stimulation via tDCS was not superior to sham stimulation in producing changes in alcohol craving (SMD = -0.08, p = .59).

Conclusions

Our meta-analysis suggests that rTMS may be superior to tDCS in reducing alcohol craving in patients with AUD. However, additional research is needed to identify optimal stimulation parameters for both non-invasive neuromodulatory techniques in AUD.

Vulnerability for alcohol use disorder after adverse childhood experiences (AUDACE): protocol for a longitudinal fMRI study assessing neuropsychobiological risk factors for relapse

BACKGROUND

Adverse childhood experiences (ACE) are common and may predispose affected individuals to various health problems, including alcohol use disorder (AUD). Although a relationship between ACE and AUD has been well-established, potential mechanisms that may underlie this relationship remain to be elucidated. The importance of these mechanisms with respect to relapse risk is of particular interest, given the clinical relevance of relapse in addictions. Thus, the aim of this study is to longitudinally assess the role of clinically relevant variables in the relationship between ACE and AUD, namely stress sensitivity, emotion processing, cue reactivity and cognitive functioning (response inhibition and working memory), in relation to relapse risk.

METHODS AND ANALYSIS

In this observational, longitudinal case-control study, 36 patients with AUD and heavy drinkers with varying degrees of ACE from a previous project (NCT03758053) as well as newly recruited participants from the same study population will be assessed. Besides measuring long-term relapse in AUD by re-examining these 36 previous participants after 2-2.5 years, factors contributing to short-term relapse will be examined by reassessing all participants on a 3-month follow-up. Furthermore, participants with no or mild ACE will be compared with participants with moderate to severe ACE to assess between-subject differences in risk factors for AUD. Questionnaires and interviews will thus be used to cover individuals' drinking behaviour and ACE. Emotion processing, stress sensitivity, cue reactivity and cognitive functioning will be assessed using task-based functional MRI (fMRI). Additionally, saliva cortisol and blood samples will be taken to measure hormonal stress response and to perform genome wide association analyses, respectively. The general linear model will be applied on the first level fMRI analyses, whereas for the second level analyses and analyses of behavioural data, t-tests, regression analyses, repeated-measures and one-way analysis of variances will be used.

ETHICS AND DISSEMINATION

This study has been approved by the ethics committee of the Medical Faculty Mannheim of Heidelberg University (ethics approval number: 2018-560N-MA with amendment from 29 June 2021). The findings of this study will be presented at conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT05048758; Pre-results, clinicaltrials.gov.

Differentiating Individuals with and without Alcohol Use Disorder Using Resting-State fMRI Functional Connectivity of Reward Network, Neuropsychological Performance, and Impulsivity Measures

Individuals with alcohol use disorder (AUD) may manifest an array of neural and behavioral abnormalities, including altered brain networks, impaired neurocognitive functioning, and heightened impulsivity. Using multidomain measures, the current study aimed to identify specific features that can differentiate individuals with AUD from healthy controls (CTL), utilizing a random forests (RF) classification model. Features included fMRI-based resting-state functional connectivity (rsFC) across the reward network, neuropsychological task performance, and behavioral impulsivity scores, collected from thirty abstinent adult males with prior history of AUD and thirty CTL individuals without a history of AUD. It was found that the RF model achieved a classification accuracy of 86.67% (AUC = 93%) and identified key features of FC and impulsivity that significantly contributed to classifying AUD from CTL individuals. Impulsivity scores were the topmost predictors, followed by twelve rsFC features involving seventeen key reward regions in the brain, such as the ventral tegmental area, nucleus accumbens, anterior insula, anterior cingulate cortex, and other cortical and subcortical structures. Individuals with AUD manifested significant differences in impulsivity and alterations in functional connectivity relative to controls. Specifically, AUD showed heightened impulsivity and hypoconnectivity in nine connections across 13 regions and hyperconnectivity in three connections involving six regions. Relative to controls, visuo-spatial short-term working memory was also found to be impaired in AUD. In conclusion, specific multidomain features of brain connectivity, impulsivity, and neuropsychological performance can be used in a machine learning framework to effectively classify AUD individuals from healthy controls.

TMS for the functional evaluation of cannabis effects and for treatment of cannabis addiction: A review

The knowledge about the effects of cannabis on human cortical brain processes is increasing. In this regard, transcranial magnetic stimulation (TMS) enables the evaluation of central nervous system function, including drug effects. Moreover, repetitive TMS (rTMS) has been used therapeutically in several substance use disorders. In this scoping review, we summarize and discuss studies that have employed TMS and rTMS techniques in users of cannabis for recreational purposes. In subjects with a history of persistent cannabis use, TMS studies showed reduced short-interval cortical inhibition (SICI). This observation points more at neurobiological changes of chronic cannabis use than to a direct effect of cannabis on gamma-aminobutyric acid (GABA) A receptors. Moreover, individuals vulnerable to becoming long-term users of cannabis may also have underlying pre-existing abnormalities in SICI. Of note, the use of cannabis is associated with an increased risk of schizophrenia, and the down-regulation of GABAergic function may play a role. Less frequent cannabis use and spontaneous craving were observed following rTMS applied to the dorsolateral prefrontal cortex (DLPFC). There is emerging evidence that the posterior cingulate cortex and the precuneus are potential targets for rTMS intervention in cannabis use disorder. However, larger and randomized trials should corroborate these encouraging findings.

Data-driven study on resting-state functional magnetic resonance imaging during early abstinence of alcohol dependence in male patients and its predictive value for relapse

BACKGROUND

Alcohol dependence is a mental disorder with a high relapse rate. However, specific neuroimaging biomarkers have not been determined for alcohol dependence and its relapse. We conducted data-driven research to investigate resting-state functional magnetic resonance imaging (rs-fMRI) during early abstinence from alcohol dependence and its potential ability to predict relapse.

METHODS

Participants included 68 alcohol-dependent patients and 68 healthy controls (HCs). The regional homogeneity (ReHo) and fractional amplitude of low-frequency fluctuations (fALFF) were compared between the alcohol dependence group and the HCs and between the relapse group and the nonrelapse group. The brain regions that presented significantly different ReHo and/or fALFF between the alcohol-dependent patients and HCs and/or between the relapsed and nonrelapsed patients were selected as the seeds to calculate the functional connectivities (FCs).

RESULTS

During a 6-month follow-up period, 52.24% of alcohol-dependent patients relapsed. A regression model for differentiating alcohol-dependent patients and HCs showed that reductions in ReHo in the left postcentral region, fALFF in the right fusiform region, and FC in the right fusiform region to the right middle cingulum were independently associated with alcohol dependence, with an area under the receiver operating characteristic curve (AUC) of 0.841. The baseline FC of the left precentral to the left cerebellum of the relapse group was significantly lower than that of the nonrelapse group. The AUC of this FC to predict relapse was 0.774.

CONCLUSIONS

Our findings contribute to advancing research on the neurobiological etiology and predictive biomarkers for relapse associated with alcohol dependence.

An Overview of Glycine Transporter Subtype 1 Inhibitors Under Preclinical and Clinical Evaluation for the Treatment of Alcohol Abuse

Abstract:

Being a historical issue that withstands multiple societal control measures, alcohol abuse remains a major healthcare problem. Despite worldwide efforts to limit consumption and educate people about its effects, consumption rates remain unchanged. Alcohol abuse arises from chronic alcohol exposure-caused permanent synaptic plasticity changes in the brain. These manifest in life-threatening withdrawal symptoms and drive relapse even after detoxification and treatment. Since ethanol has multiple targets in the human brain, it warrants a multiapproach therapy; here we introduce the potential therapeutic effects of glycine transporter subtype 1 inhibitors. We have listed the various glycine transporter 1 inhibitors used in studies of alcoholism and how they influenced glycine release from rat hippocampus was demonstrated in a preliminary study. Glycine transporters modulate both glutamatergic and glycinergic pathways: (i) glutamatergic neurotransmission plays an important role in the development of chronic changes in alcoholism as daily alcohol administration was shown to increase N-methyl-D-aspartic acid receptor activity long-term, and (ii) ethanol has access to the dopaminergic reward system via glycine receptors, being an allosteric modulator of glycine receptors. This manuscript summarises the progress and development of glycine transporter 1 inhibitors, characterizing them by their mode of action, adverse effects, and discusses their clinical applicability. Furthermore, we highlight the progress in the latest clinical trials, outline currently applied treatment methods, and offer suggestions for implementing glycine transporter 1 inhibitors into the long-term treatment of alcohol abuse.

The Significance of Toll-Like Receptors in the Neuroimmunologic Background of Alcohol Dependence

Toll-like receptors (TLR) are a group of protein belonging to the family of Pattern Recognition Receptors (PRR) which have the ability to distinguish between an organism's own antigens and foreign ones and to induce immunological response. TLR play a significant part in non-specific immunity but at the same time they are also a vital element linking non-specific response to the specific one. A growing number of data seems to indicate that the non-specific immunity mechanisms affect the development and sustenance of alcohol addiction. Alcohol damages the organism's cells not only directly but also through an increase inintestinal permeability which induces innate immune response of peripheral blood cells. The signaling pathway of Toll-like receptors located on the surface of brain immune cells intensifies the inflammatory reaction and, through modifying gene expression of proinflammatory factors, unnaturally supports it. This overly protracted "sterile inflammatory reaction" positively correlates with alcohol craving affecting also the functioning of the reward system structures and increasing the risk of relapse of alcoholism. Recurrent alcoholic binges sensitize the microglia and cause an escalation in inflammatory reaction which also leads to neurodegeneration. The induction of innate immunity signaling pathways exposes clinical symptoms of alcohol addiction such as increased impulsivity, loss of behavioral control, depressive-anxiety symptoms and cognitive dysfunctions. Traditional methods of treating alcohol addiction have tended to focus predominantly on reducing symptoms which-given the frequency of relapses-seems insufficient. The aim of the present paper is to discuss the role of toll-like receptors as elements of the immunity system which, together with the nervous system, plays a crucial part in the pathogenesis of alcohol addiction. We also wish to present pharmacotherapeutic perspectives targeted at the neuroimmunological mechanisms of alcohol addiction.

Intrinsic brain functional connectivity patterns in alcohol use disorder

Alcohol use disorder is associated with damaging effects to the brain. This study aimed to examine differences in static and dynamic intrinsic functional connectivity patterns in individuals with a history of alcohol use disorder in comparison to those with no history of alcohol abuse. A total of 55 participants consisting of 23 patients and 32 control individuals underwent neuropsychological assessments and resting-state functional magnetic resonance imaging on a 3 Tesla MRI scanner. Differences in functional connectivity between the two groups were determined using static and dynamic independent component analysis. Differences in static functional connectivity between the two groups were identified in the default mode network, attention network, frontoparietal network, frontal cortical network and cerebellar network. Furthermore, the analyses revealed specific differences in the dynamic temporal characteristics of functional connectivity between the two groups of participants, in a cluster involving key regions in reward, sensorimotor and frontal cortical functional networks, with some connections correlating with the length of sobriety and some others with the severity of drinking. The findings altogether suggest dysregulation in the intrinsic connectivity of cortico-basal ganglia-thalamo-cortical loops that may reflect persistent alcohol use disorder-related network abnormalities, compensatory recovery-related processes whereby additional neural resources are recruited to achieve normal levels of performance, or a predisposition toward developing alcohol use disorder.

Is There an Association Between Salivary Cortisol and Dropping Out of Inpatient Substance Addiction Treatments? A Prospective Repeated Measures Study

Several studies have found an association between salivary cortisol levels and dropping out of inpatient substance addiction treatment programs. The results are mixed due to variations in the study design and the lack of standardized routines for cortisol assessment. The aim of this study was to investigate whether there was (1) an association between salivary cortisol levels and dropping out from inpatient substance addiction treatments; (2) higher predictive validity for dropout in one of the cortisol indexes: Area Under the Curve with respect to ground (AUC_G) or Daily Cortisol Slope (DCS); (3) an interaction effect with time for each cortisol index; and (4) different dropout rates for sex and patients in short-term versus long-term treatment programs. This was a prospective, repeated-measures observational study. Patients (n = 173) were recruited from 2 inpatient facilities in the central region of Norway between 2018 and 2021. Salivary cortisol was measured 4 times during the treatment period, with 8 samples collected over 2 consecutive days at each time point. Cortisol levels were calculated using the cortisol indices AUC_G and DCS. Dropout was used as the outcome measure at each time point. Associations were calculated using a logistic linear regression. The results suggest a main effect of AUC_G, whereby higher levels reduce dropout risk (OR = 0.92, P = .047). An interaction with time in treatment also revealed a higher dropout risk (OR = 1.09, P = .044) during week 4 of the treatment, depending on the AUC_G. These results support using AUC_G as the recommended index when assessing cortisol, and that the relationship between cortisol levels and length of treatment should be further investigated.

An Overview of Appetite-Regulatory Peptides in Addiction Processes; From Bench to Bed Side

There is a substantial need for new pharmacological treatments of addiction, and appetite-regulatory peptides are implied as possible candidates. Appetite regulation is complex and involves anorexigenic hormones such as glucagon-like peptide-1 (GLP-1) and amylin, and orexigenic peptides like ghrelin and all are well-known for their effects on feeding behaviors. This overview will summarize more recent physiological aspects of these peptides, demonstrating that they modulate various aspects of addiction processes. Findings from preclinical, genetic, and experimental clinical studies exploring the association between appetite-regulatory peptides and the acute or chronic effects of addictive drugs will be introduced. Short or long-acting GLP-1 receptor agonists independently attenuate the acute rewarding properties of addictive drugs or reduce the chronic aspects of drugs. Genetic variation of the GLP-1 system is associated with alcohol use disorder. Also, the amylin pathway modulates the acute and chronic behavioral responses to addictive drugs. Ghrelin has been shown to activate reward-related behaviors. Moreover, ghrelin enhances, whereas pharmacological or genetic suppression of the ghrelin receptor attenuates the responses to various addictive drugs. Genetic studies and experimental clinical studies further support the associations between ghrelin and addiction processes. Further studies should explore the mechanisms modulating the ability of appetite-regulatory peptides to reduce addiction, and the effects of combination therapies or different diets on substance use are warranted. In summary, these studies provide evidence that appetite-regulatory peptides modulate reward and addiction processes, and deserve to be investigated as potential treatment target for addiction.

Behavioral consequences of the downstream products of ethanol metabolism involved in alcohol use disorder

Research concerning Alcohol Use Disorder (AUD) has previously focused primarily on either the behavioral or chemical consequences experienced following ethanol intake, but these areas of research have rarely been considered in tandem. Compared with other drugs of abuse, ethanol has been shown to have a unique metabolic pathway once it enters the body, which leads to the formation of downstream metabolites which can go on to form biologically active products. These metabolites can mediate a variety of behavioral responses that are commonly observed with AUD, such as ethanol intake, reinforcement, and vulnerability to relapse. The following review considers the preclinical and chemical research implicating these downstream products in AUD and proposes a chemobehavioral model of AUD.

Astroglia in the Vulnerability and Maintenance of Alcohol Use Disorders

Changes induced in the morphology and the multiplicity of functional roles played by astrocytes in brain regions critical to the establishment and maintenance of alcohol abuse suggest that they make an important contribution to the vulnerability to alcohol use disorders. The understanding of the relevant mechanisms accounting for that contribution is complicated by the fact that alcohol itself acts directly on astrocytes altering their metabolism, gene expression, and plasticity, so that the ultimate result is a complex interaction of various cellular pathways, including intracellular calcium regulation, neuroimmune responses, and regulation of neurotransmitter and gliotransmitter release and uptake. The recent years have seen a steady increase in the characterization of several of the relevant mechanisms, but much remains to be done for a full understanding of the astrocytes' contribution to the vulnerability to alcohol dependence and abuse and for using that knowledge in designing effective therapies for AUDs.

Ethanol enhanced MDPV- and cocaine-induced aggressive behavior in mice: Forensic implications

BACKGROUND

Reports concerning the causal link between aggressive behavior and use and abuse of different substances (i.e., alcohol, MDPV) can be found in the literature. Nonetheless, the topic concerning the effects of acute ethanol administration on MDPV and cocaine induced aggressive behavior has yet to be thoroughly investigated. The aim of this study was to investigate such synergistic effects.

MATERIALS AND METHODS

A total of 360 male mice were employed in the study. Ethanol was diluted with saline solution and administered 10 min before MDPV or cocaine injection via oral gavage needles. Similarly, MDPV and cocaine were dissolved in saline solution and administered by intraperitoneal injection. Different associations of specific drug doses were then tested. To investigate the acute effects of MDPV and cocaine and their interaction with ethanol on aggression in mice, a resident-intruder test was used.

RESULTS

Ethanol alone was ineffective at dosages of 0.05 g/kg and 0.25 g/kg but increased the aggressiveness of the mice at 0.125 g/kg. Similarly, the injection of both cocaine alone and MDPV alone did not significantly increase the aggressiveness of the mice; conversely, the combination of ethanol and cocaine and ethanol and MDPV enhanced aggression at specific ethanol dosages (0.05 g/kg and 0.125 g/kg).

CONCLUSION

This study demonstrated that acute ethanol administration enhances MDPV- and cocaine-induced aggressive behavior in mice. This aggressive response is particularly enhanced when MDVP and cocaine are coupled with specific ethanol dosages, proving that psychostimulant drugs may act synergistically under certain conditions.

Enhancement of the GluN2B subunit of glutamatergic NMDA receptors in rat brain areas after cocaine abstinence

BACKGROUND

Cocaine use disorder is associated with compulsive drug-seeking and drug-taking, whereas relapse may be induced by several factors, including stress, drug-related places, people, and cues. Recent observations strongly support the involvement of the N-methyl-D-aspartate (NMDA) receptors in cocaine use disorders and abstinence, whereas withdrawal in different environments may affect the intensification of relapse.

METHODS

The aim of this study was to examine the GluN2B subunit expression and its association with the postsynaptic density protein 95 (PSD95) in several brain structures in rats with a history of cocaine self-administration and housed either in an enriched environment or in an isolated condition. Furthermore, a selective antagonist of the GluN2B subunit-CP 101,606 (10 and 20 mg/kg) administered during exposure to cocaine or a drug-associated conditional stimulus (a cue) was used to evaluate seeking behavior in rats.

RESULTS

In rats previously self-administering cocaine, we observed an increase in the GluN2B expression in the total homogenate from the dorsal hippocampus under both enriched environment and isolation. Cocaine abstinence under isolation conditions increased the GluN2B and GluN2B/PSD95 complex levels in the PSD fraction of the prelimbic cortex in rats previously self-administering cocaine. Administration of CP 101,606 attenuated cue-induced cocaine-seeking behavior only in isolation-housed rats.

CONCLUSION

In summary, in this study we showed region-specific changes in both the expression of GluN2B subunit and NMDA receptor trafficking during cocaine abstinence under different housing conditions. Furthermore, we showed that the pharmacological blockade of the GluN2B subunit may be useful in attenuating cocaine-seeking behavior.

Adjuvant treatment with repetitive transcranial magnetic stimulation in freshly diagnosed alcohol-dependence syndrome patients from an industry: An outcome study

BACKGROUND

Studies have suggested that repetitive transcranial magnetic stimulation (rTMS) could be efficacious in the treatment of major depression and other psychiatric indications. Alcohol-dependence syndrome is difficult to treat, and the relapse rate is high, even following the standard treatment protocol. No study has been done so far in India for the use of rTMS as an adjuvant therapy in the relapse prevention of patients with alcohol-dependence syndrome. Hence, the current study is an open-label study to explore the same.

AIM

The aim of this study was to study the feasibility of rTMS in alcohol-dependence syndrome patients, the side effects if any, and the number of relapses that they may suffer from vis-a-vis patients with standard treatment protocols.

MATERIALS AND METHODS

In a prospective, open-label study design, 100 freshly diagnosed cases of alcohol-dependence syndrome were included, and after suitable randomization, half of them were given adjuvant rTMS along with standard treatment and the rest received only standard treatment. The rates of relapse into drinking were compared for both groups. The data were compiled and analyzed with appropriate statistical methods.

RESULTS

Participants given adjuvant rTMS showed significantly less number of relapses into drinking compared to the control group on standard treatment for alcohol-dependence syndrome.

CONCLUSION

In the present study, though the sample size is small, a significant change with this novel treatment has been found. Whether this change is maintained over a period of time is to be seen by other longitudinal studies.

Nalmefene attenuates neural alcohol cue-reactivity in the ventral striatum and subjective alcohol craving in patients with alcohol use disorder

RATIONALE

Alcohol use disorder is a common and devastating mental illness for which satisfactory treatments are still lacking. Nalmefene, as an opioid receptor modulator, could pharmacologically support the reduction of drinking by reducing the (anticipated) rewarding effects of alcohol and expanding the range of treatment options. It has been hypothesized that nalmefene acts via an indirect modulation of the mesolimbic reward system. So far, only a few imaging findings on the neuronal response to nalmefene are available.

OBJECTIVES

We tested the effect of a single dose of 18 mg nalmefene on neuronal cue-reactivity in the ventral and dorsal striatum and subjective craving.

METHODS

Eighteen non-treatment-seeking participants with alcohol use disorder (67% male, M = 50.3 ± 13.9 years) with a current high-risk drinking level (M = 76.9 ± 52 g of pure alcohol per day) were investigated using a cue-reactivity task during functional magnetic resonance imaging (fMRI) in a double-blind, placebo-controlled, cross-over study/design. In addition, self-reported craving was assessed before and after exposure to alcohol cues.

RESULTS

An a priori defined region of interest (ROI) analysis of fMRI data from 15 participants revealed that nalmefene reduced alcohol cue-reactivity in the ventral, but not the dorsal striatum. Additionally, the subjective craving was significantly reduced after the cue-reactivity task under nalmefene compared to placebo.

CONCLUSION

In the present study, reduced craving and cue-reactivity to alcohol stimuli in the ventral striatum by nalmefene indicates a potential anti-craving effect of this drug via attenuation of neural alcohol cue-reactivity.

Neurobiological correlates of cue-reactivity in alcohol-use disorders: A voxel-wise meta-analysis of fMRI studies

Altered brain responses to alcohol-associated stimuli are a neural hallmark of alcohol-use disorder (AUD) and a promising target for pharmacotherapy. However, findings in cue-reactivity based functional MRI (fMRI) studies are inconclusive. To investigate the neural substrates of cue-reactivity and their relevance to treatment outcomes, alcohol craving and relapse in AUD patients, we performed five meta-analyses using signed differential mapping software. Our meta-analysis revealed that alcohol cues evoke greater cue-reactivity than neutral cues in the mesocorticolimbic circuit and lower reactivity in the parietal and temporal regions in AUD patients. Compared to controls, AUD individuals displayed hyperactivations in the medial prefrontal cortex and anterior/middle part of the cingulate cortex. After receiving AUD treatment, AUD patients exhibited greater activations in the precentral gyrus but reduced activations in the bilateral caudate nucleus, insula, right DLPFC, and left superior frontal gyrus. No significant results were found in cue-reactivity correlates of alcohol craving and relapse. Our results implicate cue-induced abnormalities in corticostriatal-limbic circuits may underline the pathophysiology of AUD, and have translational value for treatment development.

Portuguese validation of the Alcohol Craving Questionnaire-Short Form-Revised

Alcohol craving has been described as a strong subjective desire to drink, being considered highly valuable in the clinical practice, as it is recognized as a strong predictor of alcohol relapse in alcohol-dependent individuals. However, to date, there is not a multifactorial questionnaire available for assessing short-term acute craving experience in Portugal. The aim of the present study was to validate a swift and efficient tool for the assessment of acute alcohol craving in a sample of Portuguese citizens. For that purpose, the Alcohol Craving Questionnaire–Short Form–Revised (ACQ-SF-R) was translated into European Portuguese and administered to a sample of 591 college participants with ages between 18 and 30 years. Results suggested that a three-factor model (i.e., Emotionality, Purposefulness, and Compulsivity) proved to be most suitable for the Portuguese sample. Overall, the ACQ-SF-R exhibited good psychometric properties, having a good internal consistency both for the general craving index (Cronbach’s α = 0.85) and each subscale (Cronbach’s α = 0.66–0.83), as well as an appropriate convergent validity with the Penn Alcohol Craving Scale (r = 0.65, p<0.001), suggesting a good construct validity. In addition, the ACQ-SF-R also showed a good concurrent validity with the Alcohol Use Disorders Identification Test (r = 0.57, p<0.001), indicating that risky alcohol use patterns are associated with increased craving scores in the ACQ-SF-R. Collectively, these findings suggest that the Portuguese version of the ACQ-SF-R can accurately measure alcohol craving at a multifactorial level, being a valid and reliable tool to use in Portuguese samples in research settings.

The role of the orbitofrontal cortex and the nucleus accumbens for craving in alcohol use disorder

This study aimed to investigate structural and functional alterations of the reward system and the neurobiology of craving in alcohol use disorder (AUD). We hypothesized reduced volume of the nucleus accumbens (NAcc), reduced structural connectivity of the segment of the supero-lateral medial forebrain bundle connecting the orbitofrontal cortex (OFC) with the NAcc (OFC-NAcc), and reduced resting-state OFC-NAcc functional connectivity (FC). Furthermore, we hypothesized that craving is related to an increase of OFC-NAcc FC. Thirty-nine recently abstinent patients with AUD and 18 healthy controls (HC) underwent structural (T1w-MP2RAGE, diffusion-weighted imaging (DWI)) and functional (resting-state fMRI) MRI-scans. Gray matter volume of the NAcc, white matter microstructure (fractional anisotropy (FA)) and macrostructure (tract length) of the OFC-NAcc connection and OFC-NAcc FC were compared between AUD and HC using a mixed model MANCOVA controlling for age and gender. Craving was assessed using the thoughts subscale of the obsessive-compulsive drinking scale (OCDS) scale and was correlated with OFC-NAcc FC. There was a significant main effect of group. Results were driven by a volume reduction of bilateral NAcc, reduced FA in the left hemisphere, and reduced tract length of bilateral OFC-NAcc connections in AUD patients. OFC-NAcc FC did not differ between groups. Craving was associated with increased bilateral OFC-NAcc FC. In conclusion, reduced volume of the NAcc and reduced FA and tract length of the OFC-NAcc network suggest structural alterations of the reward network in AUD. Increased OFC-NAcc FC is associated with craving in AUD, and may contribute to situational alcohol-seeking behavior in AUD.

Baclofen attenuates fMRI alcohol cue reactivity in treatment-seeking alcohol dependent individuals

RATIONALE

Baclofen has been shown to effect fMRI alcohol cue reactivity in alcohol dependence, but potential varying effects related to baclofen dose levels have not been examined.

OBJECTIVE

This study investigated whether baclofen attenuates craving and alcohol cue-elicited activation in alcohol-dependent treatment seekers, and the relationship between this response and clinical outcomes (Morley et al. 2018; Morley et al. 2013).

METHODS

Participants included 30 alcohol-dependent individuals who had received daily baclofen 30 mg (n = 11), 75 mg (n = 8) or placebo (n = 11) for at least 2 weeks. Using functional magnetic resonance imaging (fMRI), we examined alcohol cue-elicited neural activation during a visual alcohol cue reactivity task 120 min following treatment administration, and alcohol cue reactivity and percentage of heavy drinking days (% HDD) associations were assessed.

RESULTS

Both baclofen-treated groups reported fewer post-scan % HDD when compared to the placebo-treated group, but no subjective craving group differences were found. Increased alcohol cue-elicited activation was seen in placebo compared to the 75 mg/day baclofen participants in two clusters spanning prefrontal regions implicated in cue reactivity, chiefly frontal regions (i.e., frontal and precentral gyri, anterior cingulate cortex), but no observed alcohol cue reactivity differences between placebo and 30 mg/day baclofen groups. Post-scan % HDD was positively correlated with increased alcohol cue-elicited activation in a cluster encompassing the bilateral caudate nucleus and dorsal anterior cingulate cortex when comparing placebo versus 75 mg/day baclofen groups, and several clusters including prefrontal and mesolimbic regions when comparing placebo versus 30 mg/day baclofen groups.

CONCLUSIONS

Baclofen administration attenuates alcohol cue-elicited activation and reduced the association in baclofen-treated participants between increased activity in key drug cue reactivity regions and higher post-scan % HDD observed in placebo-treated participants, suggesting a dose-specific response effect that may lead to reduced heavy drinking in chronic alcohol-dependent individuals.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT01711125, https://clinicaltrials.gov/ct2/show /NCT01711125.

High-dose baclofen attenuates insula activation during anticipatory anxiety in treatment-seeking alcohol dependant individuals: Preliminary findings from a pharmaco-fMRI study

The GABA _B agonist, baclofen, has been shown to reduce alcohol consumption in patients with alcohol use disorder and also those with comorbid anxiety. This study aimed to evaluate the effect of baclofen versus placebo on the BOLD response during an anticipatory anxiety fMRI task in treatment seeking alcohol patients. Participants included 28 alcohol dependant individuals who had received daily baclofen 30 mg (n = 10), 75 mg (n = 8) or placebo (n = 10) for at least 2 week on a randomized controlled trial (Morley, Leung et al. 2013, Morley, Baillie et al. 2018). Using functional magnetic resonance imaging (fMRI), we examined threat cue-elicited neural activation during a threat reactivity task 120 min following administration of BAC (30 mg or 75 mg) or placebo. Whole-brain analyses revealed no significant differences between the combined BAC doses versus PL. However, there were significant decreases in anticipatory threat cue-elicited activation observed in BAC 75 mg/day compared to PL participants in the insula. In response to threat cues, high dose (75 mg/day) baclofen administration attenuates activation in the insula and inferior frontal gyrus, relative to placebo. These preliminary findings suggests that modulating emotional regulation and attentional allocation during high threat stimuli may be mediated by GABA _B receptors and may be a potential mechanism of action for baclofen's beneficial treatment effects for alcohol use disorder.

French Validation of the Alcohol Urge Questionnaire: Psychometric Properties and Relationship with Alcohol Dependence and Drinking Behavior

AIM

To validate a French translation of the Alcohol Urge Questionnaire (AUQ) that measures craving in patients with alcohol dependence.

METHOD

All patients aged > 18 years who were hospitalized for alcohol detoxification from February to May 2019 in the alcohol unit of the Rennes university hospital were eligible. A back-translated version of the AUQ was completed at admission. Patients were interviewed at the end of the 7-day detoxification program by a trained addiction psychiatrist (MS), using tablet computed-based questionnaires assessing state craving (visual analog scale), alcohol dependence severity, drinking behavior, psychological distress and physical/mental health. The same investigator assessed relapse 1 month after discharge.

RESULTS

A total of 80 inpatients were recruited and completed questionnaires. The single factor structure of the French version of the AUQ was similar to the original questionnaire, and was supported by strong internal reliability and item-scale validity. The AUQ score correlated highly acute craving measure, but moderately scales assessing the severity of alcohol dependence, drinking behavior and mental health. Relapse 1 month after discharge was significantly related to AUQ score assessed either at baseline, or with better estimate at the end of the 7-day detoxification period.

CONCLUSION

The French version of the AUQ provides a reliable measure of phasic craving, which is best described as a context-dependent single-factor variable, related to but distinct from tonic craving, dependence severity and drinking behavior. The ease of administration makes the AUQ a useful tool for French-speaking patients with alcohol dependence.

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'.

Dimensions of Craving Interact with COMT Genotype to Predict Relapse in Individuals with Alcohol Use Disorder Six Months after Treatment

(1) Background: Alcohol use disorder (AUD) is associated with poor medical, psychological, and psychosocial outcomes and approximately 60% of individuals with AUD relapse six months after treatment. Craving is a core aspect of AUD and associated with high risk of relapse. One promising avenue to improve outcomes may be in understanding the relationship between COMT genotype, craving, and treatment outcomes. (2) Methods: To this end, we assessed craving, recent drinking history, and impulsivity in 70 individuals with AUD undergoing a standard course of treatment at a regional Veteran Affairs (VA) medical center. Saliva samples were collected to determine COMT genotype. In this prospective observational study, participants were followed for six months to determine who went on to relapse after treatment. (3) Results: Results revealed a significant interaction between craving and catechol-O-methyltransferse (COMT) genotype in predicting relapse. Post hoc exploratory analyses indicated that Met/Met homozygotes reported the highest levels of craving, and craving was associated with recent drinking history. Among Val/Val homozygotes, who had higher rates of relapse, craving was associated with impulsivity. (4) Conclusions: These associations highlight that specific profiles of psychological and biological factors may be important in understanding which individuals are at highest risk of relapse following treatment. Future studies that build on these findings are warranted.

Effects of cortisol administration on craving during in vivo exposure in patients with alcohol use disorder

Alcohol-associated memories and craving play a crucial role in the development and maintenance of alcohol use disorder (AUD). As treatment options are limited in AUD, novel treatment strategies focus on the manipulation of alcohol-associated memories. The stress hormone cortisol affects various memory processes, and first clinical studies have shown that it inhibits the retrieval of disorder-specific memories and enhances extinction memory. This study aimed to investigate the effects of a single oral administration of cortisol on craving in patients with AUD during repeated in vivo exposure to alcohol pictures and the preferred alcoholic drink. In a double-blind, block-randomized, placebo-controlled cross-over design, 46 patients with AUD were treated with two sessions of in vivo exposure to alcohol. Cortisol (20 mg) or placebo was orally administered 1 h before each test day. Craving, stress, and cortisol were repeatedly measured during exposure sessions. Results show, that cortisol administration had distinct effects on craving depending on the severity of AUD and test day. While cortisol administration significantly enhanced craving during exposure on the first test day in patients with less severe AUD, it reduced craving in patients with more severe AUD. Independent of the cortisol administration, repeated in vivo exposure reduced craving from test day 1 to test day 2. In conclusion, adding cortisol to in vivo exposure might be a promising approach for reducing the strength of alcohol-associated memories and might promote the consolidation of extinction memory in patients with severe AUD. However, the differential effect of cortisol on craving depending on AUD severity cannot be conclusively explained and highlights the need for future studies elucidating the underlying mechanism.

Neurofeedback Training versus Treatment-as-Usual for Alcohol Dependence: Results of an Early-Phase Randomized Controlled Trial and Neuroimaging Correlates

INTRODUCTION

Alcohol dependence is one of the most common substance use disorders, and novel treatment options are urgently needed. Neurofeedback training (NFT) based on real-time functional magnetic resonance imaging (rtf-MRI) has emerged as an attractive candidate for add-on treatments in psychiatry, but its use in alcohol dependence has not been formally investigated in a clinical trial. We investigated the use of rtfMRI-based NFT to prevent relapse in alcohol dependence.

METHODS

Fifty-two alcohol-dependent patients from the UK who had completed a detoxification program were randomly assigned to a treatment group (receiving rtfMRI NFT in addition to standard care) or the control group (receiving standard care only). At baseline, alcohol consumption was assessed as the primary outcome measure and a variety of psychological, behavioral, and neural parameters as secondary outcome measures to determine feasibility and secondary training effects. Participants in the treatment group underwent 6 NFT sessions over 4 months and were trained to downregulate their brain activation in the salience network in the presence of alcohol stimuli and to upregulate frontal activation in response to pictures related to positive goals. Four, 8, and 12 months after baseline assessment, both groups were followed up with a battery of clinical and psychometric tests.

RESULTS

Primary outcome measures showed very low relapse rates for both groups. Analysis of neural secondary outcome measures indicated that the majority of patients modulated the salience system in the desired directions, by decreasing activity in response to alcohol stimuli and increasing activation in response to positive goals. The intervention had a good safety and acceptability profile.

CONCLUSION

We demonstrated that rtfMRI-neurofeedback targeting hyperactivity of the salience network in response to alcohol cues is feasible in currently abstinent patients with alcohol dependence.

The physiological responses to acute stress in alcohol-dependent patients: A systematic review

Dysregulation of physiological stress reactivity plays a key role in the development and relapse risk of alcohol dependence. This article reviews studies investigating physiological responses to experimentally induced acute stress in patients with alcohol dependence. A systematic search from electronic databases resulted in 3641 articles found and after screening 62 articles were included in our review. Studies are analyzed based on stress types (i.e., social stress tasks and nonsocial stress tasks) and physiological markers (i.e., the nervous system, the endocrine system, somatic responses and the immune system). In studies applying nonsocial stress tasks, alcohol-dependent patients were reported to show a blunted stress response compared with healthy controls in the majority of studies applying markers of adrenocorticotropic hormone and cortisol. In studies applying social stress tasks, findings are inconsistent, with less than half of the studies reporting altered physiological stress responses in patients. We discuss the impact of duration of abstinence, comorbidities, baseline physiological arousal and intervention on the discrepancy of study findings. Furthermore, we review evidence for an association between blunted physiological stress responses and the relapse risk among patients with alcohol dependence.

Game-based learning environments affect frontal brain activity

Inclusion of game elements in learning environments to increase motivation and learning outcome is becoming increasingly popular. However, underlying mechanisms of game-based learning have not been studied sufficiently yet. In the present study, we investigated effects of game-based learning environments on a neurofunctional level. In particular, 59 healthy adults completed a game-based version (including game elements such as a narrative and virtual incentives) as well as a non-game-based version of a number line estimation task, to improve fractional knowledge, while their brain activity was monitored using near-infrared spectroscopy. Behavioral performance was comparable across the two versions, although there was a tendency that less errors were made in the game-based version. However, subjective user experience differed significantly between versions. Participants rated the game-based version as more attractive, novel, and stimulating but less efficient than the non-game-based version. Additionally, positive affect was reported to be higher while engaging in the game-based as compared to the non-game-based task version. Corroborating these user reports, we identified increased brain activation in areas associated with emotion and reward processing while playing the game-based version, which might be driven by rewarding elements of the game-based version. Moreover, frontal areas associated with attention were also more activated in the game-based version of the task. Hence, we observed converging evidence on a user experience and neurofunctional level indicating that the game-based version was more rewarding as well as emotionally and attentionally engaging. These results underscore the potential of game-based learning environments to promote more efficient learning by means of attention and reward up-tuning.