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.

Evaluating Craving in Alcohol Use Disorder: Psychometric Characteristics of the Craving Typology Questionnaire-15 (CTQ-15)

AIMS

The Craving Typology Questionnaire (CTQ) is a psychometric instrument used to assess alcohol craving in normal controls and subjects with alcohol use disorder (AUD). It allows a dimensional self-rating assessment of craving according to a three-pathway psychobiological model of craving distinguishing craving into a reward, relief and obsessive component. The aim of the present study is to evaluate psychometric properties of the CTQ-15, a revised version of CTQ with 15 items.

METHODS

The CTQ-15 was firstly administered to two groups of control subjects, one (414 subjects) used for the exploratory factor analysis and the other one (415 subjects) for the confirmatory factor analysis. A three-factor model was assessed and compared to alternative models.

RESULTS

The resulting structure was in line with the original scale CTQ. Obsessive craving accounted for 15.20% of the total variance, relief craving for the 13.99% and reward craving for 13.13% of the total variance. The three-factor model (M1) reached good fit indices (CFI = 0.96, TLI = 0.95, RMSEA = 0.06 and SRMR = 0.05) and was significantly better than other alternative models. Reliability showed good internal consistency for each scale, i.e. obsessive craving (α = 0.92), relief craving (α = 0.82) and reward craving (α = 0.81).

CONCLUSIONS

The CTQ-15 proved to be reliable and practical for identifying the three dimensions of craving in clinical practice. Craving plays a crucial role in the mechanisms of dependence and relapse; thus, characterizing the craving can be fundamental to a targeted drug therapy.

The influence of anxiety symptoms on clinical outcomes during baclofen treatment of alcohol use disorder: A systematic review and meta-analysis

Given the high coexistence of anxiety symptoms in people with alcohol use disorder (AUD), we aimed to determine the influence of anxiety symptoms on outcomes in patients with AUD treated with the GABA_B receptor agonist baclofen. A meta-analysis of 13 comparisons (published 2010-2020) including baseline and outcome data on alcohol consumption and anxiety after 12 weeks was undertaken. There were significantly higher rates of abstinent days in patients treated with baclofen compared to placebo (p = 0.004; high certainty evidence); specifically in those with higher baseline anxiety levels (p < 0.00001; high certainty evidence) compared to those with lower baseline anxiety levels (p = 0.20; moderate certainty evidence). The change in anxiety ratings over 12 weeks did not differ between those treated with baclofen or placebo (p = 0.84; moderate certainty evidence). This may be due to different anxiety constructs being measured by scales not validated in this patient group, or that anxiety is not a biobehavioral mechanism by which baclofen may reduce alcohol drinking. Given the prevalence of anxiety symptoms in AUD all these factors warrant further research.

The Neural Processes Interlinking Social Isolation, Social Support, and Problem Alcohol Use

BACKGROUND

Subjective feeling of social isolation, as can be measured by perceived burdensomeness (PB), is a major risk factor for alcohol misuse. Heightened PB is associated with elevated stress response and diminished cognitive control, both of which contribute to problem drinking. Here, we sought to identify the neural substrates underlying the relationship between PB and alcohol misuse.

METHODS

We employed resting-state functional magnetic resonance imaging data collected from 61 problem drinkers to characterize the functional connectivity of the hypothalamus and ventral striatum (VS) in relation to PB. We specifically examined whether the connectivities of the hypothalamus and VS were differentially influenced by PB to produce contrasting effects on alcohol use. Finally, we evaluated how individual differences in social support modulate the inter-relationships of social isolation, neural connectivity, and the severity of problem drinking.

RESULTS

Whole-brain multiple regressions show a positive relationship between PB and hypothalamic connectivity with the hippocampus and an inverse pattern for VS connectivity with the middle frontal gyrus. Difference in strength between the 2 connectivities predicted the severity of problem drinking, suggesting an imbalance involving elevated hypothalamic and diminished prefrontal cortical modulation in socially isolated problem drinkers. A path analysis further revealed that the lack of social support was associated with a bias toward low prefrontal connectivity, which in turn increased PB and facilitated problem drinking.

CONCLUSIONS

Altered hypothalamus and VS connectivity may underlie problem drinking induced by social isolation. The current findings also highlight the important role of social support as a potential protective factor against alcohol misuse.

Alcohol Withdrawal and Proopiomelanocortin Neuropeptides in an Animal Model of Alcohol Dependence

BACKGROUND

Alcohol is one of the leading threats to health worldwide. Craving for alcohol makes abstinence a difficult challenge by maintaining alcohol dependence. Many studies suppose the hypothalamic-pituitary-adrenal axis, especially the proopiomelanocortin (POMC)-derived neuropeptides, to mediate craving during withdrawal in alcohol dependence. Evidence is available that the two POMC proteins, α-melanocyte-stimulating hormone (α-MSH) and β-endorphin (β-END) are altered by alcohol consumption and influence alcohol consumption, respectively.

OBJECTIVES

We investigated the dynamics of α-MSH and β-END during alcohol withdrawal and the influence of intraperitoneal administration of either α-MSH or β-END in an established rodent model (Wistar rats) for alcohol dependence.

RESULTS

After long-term alcohol self-administration over 12 months and repeated deprivation periods for 3 days, we found a significant decrease in α-MSH levels during withdrawal in rodents (p = 0.006) compared to controls, while β-END levels remained unchanged. Treatment with intraperitoneally administered α-MSH and β-END did not affect alcohol drinking behavior after deprivation.

CONCLUSION

We demonstrate the effects of alcohol deprivation on α-MSH in alcohol-dependent rodents, which appear to mimic α-MSH alteration found after fasting periods during appetite regulation. Therefore, low α-MSH levels are a possible indicator for craving in alcohol-dependent individuals and hence would be a potential target for anti-craving treatment.

High doses of Baclofen as suicide attempt in patients with alcohol use disorders - A serious concern

Baclofen is increasingly being used as an off label anti-craving agent in alcohol use disorders in various parts of the world. The lack of proper recommendations regarding the dosage has important implications for safety in clinical management. In this context, we report two patients who were started with Baclofen as an anti-craving agent, and later developed serious complications following acute self inflicted overdose. We also highlight the important mechanisms of such complications and precautions that needs to be exerted while prescribing.

Leptin levels are reduced by intravenous ghrelin administration and correlated with cue-induced alcohol craving

Increasing evidence supports the role of appetite-regulating pathways, including ghrelin and leptin, in alcoholism. This study tested the hypothesis that intravenous exogenous ghrelin administration acutely decreases endogenous serum leptin levels, and that changes in leptin levels negatively correlate with alcohol craving. This was a double-blind, placebo-controlled human laboratory study. Non-treatment-seeking, alcohol-dependent, heavy drinkers (n=45) were randomized to receive intravenous ghrelin or placebo, followed by a cue-reactivity procedure, during which participants were exposed to neutral (juice) and alcohol trial cues. There was a main effect for intravenous ghrelin administration, compared with placebo, in reducing serum leptin levels (P<0.01). Post hoc analysis showed significant differences in serum leptin levels at the alcohol trial (P<0.05) that persisted at the end of the experiment (P<0.05). By contrast, there were no significant differences in serum leptin levels at the juice trial (P=not significant (NS)). The change of serum leptin level at the alcohol trial correlated with the increase in alcohol urge (P<0.05), whereas urge to drink juice was not correlated with the leptin change at the juice trial (P=NS). These findings provide preliminary evidence of ghrelin-leptin cross-talk in alcoholic individuals and suggest that their relationship may have a role in alcohol craving.

Investigating dimensionality and measurement bias of DSM-5 alcohol use disorder in a representative sample of the largest metropolitan area in South America

BACKGROUND

Given the recent launch of a new diagnostic classification (DSM-5) for alcohol use disorders (AUD), we aimed to investigate its dimensionality and possible measurement bias in a non-U.S.

METHODS

The current analyses were restricted to 948 subjects who endorsed drinking at least one drink per week in the past year from a sample of 5037 individuals. Data came from São Paulo Megacity Project (which is part of World Mental Health Surveys) collected between 2005 and 2007. First, exploratory factor analysis (EFA) was carried out to test for the best dimensional structure for DSM-5-AUD criteria. Then, item response theory (IRT) was used to investigate the severity and discrimination properties of each criterion of DSM-5-AUD. Finally, differential criterion functioning (DCF) were investigated by socio-demographics (income, gender, age, employment status, marital status and education). All analyses were performed in Mplus software taking into account complex survey design features.

RESULTS

The best EFA model was a one-dimensional model. IRT results showed that the criteria "Time Spent" and "Given Up" have the highest discrimination and severity properties, while the criterion "Larger/Longer" had the lowest value of severity, but an average value of discrimination. Only female gender had DCF both at criterion- and factor-level, rendering measurement bias.

CONCLUSION

This study reinforces the existence of a DSM-5-AUD continuum in the largest metropolitan area of South America, including subgroups that had previously higher rates of alcohol use (lower educational/income levels). Lower DSM-5-AUD scores were found in women.

Intravenous ghrelin administration increases alcohol craving in alcohol-dependent heavy drinkers: a preliminary investigation

BACKGROUND

There is a need to identify novel pharmacologic targets to treat alcoholism. Animal and human studies suggest a role for ghrelin in the neurobiology of alcohol dependence and craving. Here, we were the first to test the hypothesis that intravenous administration of exogenous ghrelin acutely increases alcohol craving.

METHODS

This was a double-blind, placebo-controlled human laboratory proof-of-concept study. Nontreatment-seeking, alcohol-dependent, heavy-drinking individuals were randomized to receive intravenous ghrelin 1 mcg/kg, 3 mcg/kg or 0 mcg/kg (placebo), followed by a cue-reactivity procedure, during which participants were exposed to neutral (juice) and alcohol cues. The primary outcome variable was the increase in alcohol craving (also called urge) for alcohol, assessed by the Alcohol Visual Analogue Scale.

RESULTS

Out of 103 screenings, 45 individuals received the study drug. Repeated measures of analysis of covariance revealed a group effect across ghrelin doses in increasing alcohol craving (p < .05). A dose-specific examination revealed a significant effect of ghrelin 3 mcg/kg versus placebo in increasing alcohol craving (p < .05) with a large effect size (d = .94). By contrast, no significant ghrelin effect was found in increasing either urge to drink juice or food craving (p = ns). No significant differences in side effects were found (p = ns).

CONCLUSIONS

Intravenous administration of exogenous ghrelin increased alcohol craving in alcohol-dependent heavy-drinking individuals. Although the small sample requires confirmatory studies, these findings provide preliminary evidence that ghrelin may play a role in the neurobiology of alcohol craving, thus demonstrating a novel pharmacologic target for treatment.

Alcohol consumption in young adults: the role of multisensory imagery

Little is known about the subjective experience of alcohol desire and craving in young people. Descriptions of alcohol urges continue to be extensively used in the everyday lexicon of young, non-dependent drinkers. Elaborated Intrusion (EI) Theory contends that imagery is central to craving and desires, and predicts that alcohol-related imagery will be associated with greater frequency and amount of drinking. This study involved 1535 age stratified 18-25 year olds who completed an alcohol-related survey that included the Imagery scale of the Alcohol Craving Experience (ACE) questionnaire. Imagery items predicted 12-16% of the variance in concurrent alcohol consumption. Higher total Imagery subscale scores were linearly associated with greater drinking frequency and lower self-efficacy for moderate drinking. Interference with alcohol imagery may have promise as a preventive or early intervention target in young people.

Craving Typology Questionnaire (CTQ): a scale for alcohol craving in normal controls and alcoholics

INTRODUCTION

Craving is commonly thought to play a crucial role both in the transition from controlled drinking to alcohol dependence and in the mechanism underlying relapse. However there is no consensus on its definition, and on its correct assessment. Another significant hindrance is that craving is almost certainly a multi-faceted construct. To this respect a three pathway psychobiological model able to differentiate craving into a reward, relief, and obsessive component has been suggested.

METHODS

CTQ was administered to 547 control subjects and to 100 alcohol dependent patients. The dimensional structure of the questionnaire, through the principal component analysis, the reliability and the threshold values were evaluated in both the control and clinical sample.

RESULTS

The results showed and confirmed that the CTQ is composed of three dimensions. Cronbach's alpha coefficients suggest that the questionnaire is reliable. Alcohol-dependent subjects had a significantly higher mean score as compared to the normative sample in both Reward, Relief, Obsessive craving. Younger age correlated with higher scores on Reward craving (r=0.38; p<0.001) and males reported significantly higher scores than women on Reward craving (t=4.36; p<0.001).

DISCUSSION

CTQ showed to be a reliable and valid questionnaire to distinguish a normative sample from pathological individuals. The average scores obtained represent the first normative data available for this questionnaire. Identifying a craving type may represent an important predicting or matching variable for anti-craving psychotropics. More research is needed with respect to CTQ's external validity, i.e. correlations with phenotypic, endophenotypic and genetic indicators of relief, reward and obsessive drinking.

Providing information about the neurobiology of alcohol use disorders to close the 'referral to treatment gap'

Only a small proportion of the 18 million Americans who could benefit from alcohol treatment actually receive it. Disseminating information on the neurobiological base of alcohol disorders may be useful in removing the prevailing barriers to accepting a referral to alcohol treatment. Nurses, guided by a set of clinical strategies known as screening, brief intervention, and referral to treatment, can be instrumental in closing this treatment gap.

Measurement of alcohol craving

Despite considerable research activity and application in treatment, the construct of craving remains poorly understood. We propose that cravings and urges are cognitive-emotional events in time, characterised by frequency, duration, intensity and salience. Commonly used measures of alcohol craving are reviewed, and their strengths and weaknesses identified. Most measures confound craving with behaviours, or with separable cognitive phenomena such as expectancies, intentions, or perceived behavioural control. These confounds have limited our advances in understanding the determinants and consequences of craving. Based on the criteria applied in this review, among the better performing multi-item measures are the Penn Alcohol Craving Scale and Obsessive subscale of the Obsessive-Compulsive Drinking Scale. Optimal assessment strategies are likely to involve daily assessments of peak intensity of cravings, desires or urges and of the frequency and duration of craving episodes. Of particular interest are measures of intensity at times when individuals are at risk of drinking or of other functional impacts from craving.

The relationship of appetitive, reproductive and posterior pituitary hormones to alcoholism and craving in humans

A significant challenge for understanding alcoholism lies in discovering why some, but not other individuals, become dependent on alcohol. Genetic, environmental, cultural, developmental, and neurobiological influences are recognized as essential factors underlying a person's risk for becoming alcohol dependent (AD); however, the neurobiological processes that trigger this vulnerability are still poorly understood. Hormones are important in the regulation of many functions and several hormones are strongly associated with alcohol use. While medical consequences are important, the primary focus of this review is on the underlying confluence of appetitive/feeding, reproductive and posterior pituitary hormones associated with distinct phases of alcoholism or assessed by alcohol craving in humans. While these hormones are of diverse origin, the involvement with alcoholism by these hormone systems is unmistakable, and demonstrates the complexity of interactions with alcohol and the difficulty of successfully pursuing effective treatments. Whether alcohol associated changes in the activity of certain hormones are the result of alcohol use or are the result of an underlying predisposition for alcoholism, or a combination of both, is currently of great scientific interest. The evidence we present in this review suggests that appetitive hormones may be markers as they appear involved in alcohol dependence and craving, that reproductive hormones provide an example of the consequences of drinking and are affected by alcohol, and that posterior pituitary hormones have potential for being targets for treatment. A better understanding of the nature of these associations may contribute to diagnosing and more comprehensively treating alcoholism. Pharmacotherapies that take advantage of our new understanding of hormones, their receptors, or their potential relationship to craving may shed light on the treatment of this disorder.

Effects of alcohol availability, access to alcohol, and naltrexone on self-reported craving and patterns of drinking in response to an alcohol-cue availability procedure

OBJECTIVE

Craving has long been cited by patients and providers as a principal construct in alcohol use disorders and an essential target for treatment. The goal of the current study was to examine the effects of alcohol availability (20% vs. 80% availability), access to alcohol ("open" vs. "locked" trials), and medication (oral naltrexone [Revia] vs. placebo) on self-reported craving and two behavioral measures of drinking (latency of attempt to access alcohol, amount of alcohol consumed when access permitted) in response to an alcohol-cue availability procedure.

METHOD

Non-treatment-seeking, alcohol-dependent men and women (N = 58) self-referred for an alcohol administration study and were administered a modified alcohol-cue availability procedure under two medication conditions (naltrexone, placebo) using a within-subjects, repeated-measures design.

RESULTS

Analyses demonstrated that the experimental manipulations used in this study had differential effects on craving and patterns of drinking. Specifically, reduced availability of alcohol (i.e., when alcohol was available in only 20% as opposed to 80% of trials) resulted in greater amounts of alcohol consumed per open trial; the unanticipated blocking of access to alcohol (i.e., a "locked" trial during the 80% availability condition) triggered more rapid attempts to obtain alcohol on subsequent trials. Naltrexone, relative to placebo, was associated with significant reductions in cravings for alcohol.

CONCLUSIONS

Taken together, these findings offer partial support for the cognitive processing model and reinforce the utility of evaluating both self-report and behavioral indicators of motivation to drink in studies designed to identify factors associated with the construct of craving.

Feed-forward mechanisms: addiction-like behavioral and molecular adaptations in overeating

Food reward, not hunger, is the main driving force behind eating in the modern obesogenic environment. Palatable foods, generally calorie-dense and rich in sugar/fat, are thus readily overconsumed despite the resulting health consequences. Important advances have been made to explain mechanisms underlying excessive consumption as an immediate response to presentation of rewarding tastants. However, our understanding of long-term neural adaptations to food reward that oftentimes persist during even a prolonged absence of palatable food and contribute to the reinstatement of compulsive overeating of high-fat high-sugar diets, is much more limited. Here we discuss the evidence from animal and human studies for neural and molecular adaptations in both homeostatic and non-homeostatic appetite regulation that may underlie the formation of a "feed-forward" system, sensitive to palatable food and propelling the individual from a basic preference for palatable diets to food craving and compulsive, addiction-like eating behavior.

Ghrelin system in alcohol-dependent subjects: role of plasma ghrelin levels in alcohol drinking and craving

Animal studies suggest that the gut-brain peptide ghrelin plays an important role in the neurobiology of alcohol dependence (AD). Human studies show an effect of alcohol on ghrelin levels and a correlation between ghrelin levels and alcohol craving in alcoholics. This investigation consisted of two studies. Study 1 was a 12-week study with alcohol-dependent subjects, where plasma ghrelin determinations were assessed four times (T0-T3) and related to alcohol intake and craving [Penn Alcohol Craving Score (PACS) and Obsessive Compulsive Drinking Scale (OCDS)]. Serum growth hormone levels and assessment of the nutritional/metabolic status were also performed. Study 2 was a pilot case-control study to assess ghrelin gene polymorphisms (Arg51Gln and Leu72Met) in alcohol-dependent individuals. Study 1 showed no significant differences in ghrelin levels in the whole sample, while there was a statistical difference for ghrelin between non-abstinent and abstinent subjects. Baseline ghrelin levels were significantly and positively correlated with the PACS score at T1 and with all craving scores both at T2 and T3 (PACS, OCDS, obsessive and compulsive OCDS subscores). In Study 2, although there was a higher frequency of the Leu72Met ghrelin gene polymorphism in alcohol-dependent individuals, the distribution between healthy controls and alcohol dependent individuals was not statistically significant. This investigation suggests that ghrelin is potentially able to affect alcohol-seeking behaviors, such as alcohol drinking and craving, representing a new potential neuropharmacological target for AD.

Biological mechanisms in alcohol dependence--new perspectives

Neurobiological research in alcohol dependence has led to a new understanding of this addictive disease. While some important mechanisms like alterations in the mesolimbic reward system or changes in the hypothalamus-pituitary-adrenocortical axis have been well studied, other possible neurobiological mechanisms are still unrevealed. This applies for the role of specific neuroendocrinological pathways like the appetite-regulating system and the modification of gene expression, particularly the influence of genetic variants of transcription factors or epigenetic mechanism like DNA methylation or histone acetylation. This review describes the current knowledge regarding these factors, focusing particularly on the role of appetite- and volume-regulating hormones, the role of genetic variants of specific transcription factors and the function of epigenetic alterations in the genomic sequence of candidate genes for alcohol dependence. A further understanding of the influence of transcription factors and epigenetic regulation may help to elucidate the pathophysiological mechanisms in the neurobiology of alcohol dependence.

Role of feeding-related pathways in alcohol dependence: A focus on sweet preference, NPY, and ghrelin

Converging research evidence suggests that alcohol and food-seeking behaviors share common neural pathways. There is preclinical and clinical evidence linking the consumption of sweets to alcohol intake in both animals and humans. In addition, a growing body of animal and human literature suggests the involvement of "feeding-related" peptides in alcohol-seeking behavior. In particular, both central and peripheral appetitive peptides have shown a possible role in alcohol dependence. The present mini-review will summarize the literature on the link between sweet preference and alcohol dependence, and on the role of feeding-related peptides in alcohol dependence. Specifically, in an attempt to narrow the field, the present mini-review will focus on 2 specific pathways, the central neuropeptide Y and the peripheral gut peptide ghrelin. Although more research is needed, data available suggest that studying feeding-related pathways in alcohol dependence may have theoretic, biologic, diagnostic, and therapeutic implications.