Human laboratory paradigms in alcohol research

Characterizing alcohol cue reactive and non-reactive individuals with alcohol use disorder

PURPOSE

Exposure to alcohol-related cues is thought to elicit a conditional response characterized by increased craving in individuals with alcohol use disorder (AUD). In the context of AUD research, it is important to consider that not all individuals with an AUD are alcohol cue reactive. This study systematically examined subjective alcohol cue reactivity and its clinical and drinking correlates in individuals with an AUD enrolled in a human laboratory pharmacotherapy trial.

METHODS

Individuals with current moderate-to-severe AUD (N = 52) completed a standard alcohol cue exposure paradigm and individual difference assessments as part of a human laboratory pharmacotherapy trial (NCT04249882). We classified participants as cue reactive (CR+) and cue non-reactive (CR-), as indicated by self-reported, subjective alcohol urge, and examined group differences in baseline clinical characteristics and drinking outcomes over the course of the trial.

RESULTS

Twenty participants (38%) were identified as CR+, while 32 participants (62%) were identified as CR-. The CR+ and CR- groups did not differ in baseline drinking and AUD clinical characteristics, but the groups differed in race composition (p = 0.02) and smoking prevalence (p = 0.04) such that the CR+ group had lower prevalence of smokers. The CR+, compared with the CR-, group drank more during the trial titration period (p = 0.03). Both groups reduced drinking across the trial (p's < 0.001), but the CR+ group exhibited a smaller reduction in drinking, compared with the CR- group (time x group, p = 0.029; CR-, p < 0.0001; CR+: p = 0.01).

CONCLUSION

Results indicate that cue reactivity is a heterogenous construct. Recognizing this heterogeneity, and the clinical factors associated with it, is critical to advancing this paradigm as an early efficacy marker in AUD research.

Leveraging meta-regression to test if medication effects on cue-induced craving are associated with clinical efficacy

RATIONALE

The alcohol cue exposure paradigm is a common method for evaluating new treatments for alcohol use disorder (AUD); however, it is unclear if medication-related reductions in cue-induced craving in the human laboratory can predict the clinical success of those medications in reducing alcohol consumption during clinical trials.

OBJECTIVES

To use a novel meta-analytic approach to test whether medication effect sizes on cue-induced alcohol craving are associated with clinical efficacy in clinical trials.

METHOD

We searched the literature for medications tested for AUD treatment using both the alcohol cue-reactivity paradigm and randomized clinical trials (RCTs). For alcohol cue-reactivity studies, we computed medication effect sizes for cue-induced alcohol craving (k = 36 studies, 15 medications). For RCTs, we calculated medication effect sizes for heavy drinking and abstinence (k = 139 studies, 19 medications). Using medication as the unit of analysis, we applied the Williamson-York bivariate weighted least squares estimation to account for errors in both independent and dependent variables. We also conducted leave-one-out cross validation simulations to examine the predictive utility of cue-craving medication effect sizes on RCT heavy drinking and abstinence endpoints.

RESULTS

There was no significant relationship between medication effects on cue-induced alcohol craving in the human laboratory and medication effects on heavy drinking ( β ^ = 0.253, SE = 0.189, p = 0.090) and abstinence ( β ^ = 0.829, SE = 0.747, p = 0.133) in RCTs.

CONCLUSIONS

The preliminary results of the current study challenge the assumption that alcohol cue-reactivity alone can be used as an early efficacy indicator for AUD pharmacotherapy development. These findings suggest that a wider range of early efficacy indicators and experimental paradigms be considered for Phase II testing of novel compounds.

Cannabis demand and use among veterans: A prospective examination

OBJECTIVE

Cannabis demand (i.e., relative value), assessed cross-sectionally via a hypothetical marijuana purchase task (MPT), has been associated with use, problems, and dependence symptoms, among others. However, limited work exists on the prospective stability of the MPT. Furthermore, cannabis demand among veterans endorsing cannabis use, and the prospective cyclical relationship between demand and use over time, have yet to be investigated.

METHOD

Two waves of data from a veteran sample (N = 133) reporting current (past 6-month) cannabis use were analyzed to assess stability in cannabis demand over 6 months. Autoregressive cross-lagged panel models (CLPMs) assessed the longitudinal associations between demand indices (i.e., intensity, Omax, Pmax, breakpoint) and cannabis use.

RESULTS

Baseline cannabis use predicted greater intensity (β = .32, p < .001), Omax (β = .37, p < .001), breakpoint (β = .28, p < .001), and Pmax (β = .21, p = .017) at 6 months. Conversely, baseline intensity (β = .14, p = .028), breakpoint (β = .12, p = .038), and Pmax (β = .12, p = .043), but not Omax, predicted greater use at 6 months. Only intensity demonstrated acceptable prospective reliability.

CONCLUSIONS

Cannabis demand demonstrated stability over 6 months in CLPM models, varying along with natural changes in cannabis use. Importantly, intensity, Pmax, and breakpoint displayed bidirectional predictive associations with cannabis use, and the prospective pathway from use to demand was consistently stronger. Test-retest reliability ranged from good to poor across indices. Findings highlight the value of assessing cannabis demand longitudinally, particularly among clinical samples, to determine how demand fluctuates in response to experimental manipulation, intervention, and treatment. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Are medication effects on subjective response to alcohol and cue-induced craving associated? A meta regression study

RATIONALE

Alcohol administration and cue-reactivity paradigms are frequently used to screen for the initial efficacy of medications for alcohol use disorder (AUD). While medication effects on the primary outcomes for these paradigms are assumed to be qualitatively related, there is a critical lack of quantitative evidence to support this hypothesis.

OBJECTIVES

The study aims to test the relationship between medication effect sizes on subjective response to alcohol administration and medication effect sizes for cue-induced craving to cue exposure, using meta-analysis.

METHODS

Systematic literature searches were conducted to identify randomized trials, wherein AUD medications were tested using the alcohol administration and/or cue-reactivity paradigms. From these studies, descriptive statistics were collected to compute medication effect sizes on the primary outcomes for each respective paradigm. With medication as the unit of analysis, medication effect sizes in alcohol administration studies were compared with medication effect sizes in cue-reactivity studies using the Williamson-York regression which allows for meta-regression across independent samples.

RESULTS

Medication effect sizes on alcohol-induced stimulation and alcohol-induced craving were not significantly associated with medication effect sizes on cue-induced alcohol craving (k stimulation = 10 medications, [Formula: see text] and k craving = 11 medications, [Formula: see text] (SE = 0.237), [Formula: see text]), respectively. Medication effect sizes on alcohol-induced sedation were significantly associated with medication effects on cue-induced craving (k = 10 medications, [Formula: see text] (SE = 0.258), [Formula: see text]), such that medications that increased alcohol-induced sedation were more likely to reduce cue-induced alcohol craving.

CONCLUSIONS

With the exception of alcohol-induced sedation, there is little quantitative evidence of medication effects on subjective response domains measured during alcohol administration parallel medication effects on cue-induced alcohol craving. To provide additional context to the current study, future work should examine whether cue-reactivity findings predict clinical trial outcomes.

Testing pharmacotherapies for alcohol use disorder with cue exposure paradigms: A systematic review and quantitative synthesis of human laboratory trial methodology

Alcohol cue exposure is a widely used experimental paradigm for screening pharmacotherapies for alcohol use disorder (AUD). Medication-related reductions in cue-reactivity signal early efficacy and inform medications development. Yet, across trials, the design of cue exposure, parameter testing, and outcome reporting is heterogeneous. This systematic review is a quantitative synthesis of trial methodologies and effect size estimation for AUD medication-related craving and psychophysiological outcomes under the cue exposure paradigm. A PubMed search was conducted on January 3, 2022 based on identified pharmacotherapies for peer-reviewed articles reported in English. Study-level characteristics, including sample descriptors, paradigm design, analytic approach, and Cochrane Risk of Bias, along with descriptive statistics for cue-exposure outcomes, were coded by two independent raters. Study-level effect sizes were estimated for craving and psychophysiological outcomes separately and sample-level effect sizes were calculated for each medication. Thirty-six trials, comprising 1640 participants and testing 19 different medications satisfied eligibility criteria. All studies reported on biological sex (71% male participants on average). The exposure paradigms implemented used in vivo (n = 26), visual (n = 8), and audio script (n = 2) cues. Some trials included means for craving by medication condition in text (k = 7) or figures (k = 18). The quantitative synthesis included 63 effect sizes (craving kes  = 47; psychophysiological kes  = 16) from 28 unique randomized trials testing 15 medications for effects on cue reactivity. For cue-induced craving, eight medications (kes range: 1-12) demonstrated small-to-medium effects (Cohen's d range: |0.24-0.64|) compared to placebo, with individuals randomized to receive medication reporting lower craving following cue exposure. Recommendations are provided to promote further consilience, so that the utility of cue exposure paradigms can be maximized in the development of effective AUD pharmacotherapies. Future work should explore the predictive utility of medication-related reductions in cue-reactivity on clinical outcomes.

Sex moderates effects of alcohol and cannabis co-use on alcohol and stress reactivity

BACKGROUND

Simultaneous or concurrent use (co-use) of alcohol and cannabis is associated with greater use of both substances over time, academic difficulties, more severe substance use consequences, and adverse impacts on cognitive functioning than the use of a single substance or no substance use. This study examined potential neural mechanisms underlying co-use behaviors in comparison to single substance use. Specifically, we compared alcohol cue reactivity and stress-cue reactivity among individuals who reported frequent same-day co-use of alcohol and cannabis and individuals who reported only alcohol use.

METHODS

The sample included 88 individuals (41 women) who reported only alcohol use and 24 individuals (8 women) who reported co-use of alcohol and cannabis on at least 50% of drinking occasions. All participants completed fMRI stress and alcohol cue reactivity tasks. Because of known sex effects on stress reactivity and alcohol cue reactivity, we tested sex by co-use interactions.

RESULTS

During alcohol cue presentation, co-users had less activation in the thalamus and dorsomedial prefrontal cortex than alcohol-only users, effects that were driven by differences in responses to neutral cues. Examination of stress cue reactivity revealed sex by co-use interactions in the lingual gyrus, with women co-users showing a greater difference between negative and neutral cue reactivity than all other groups. In addition, women co-users had greater connectivity between the nucleus accumbens and both the medial orbitofrontal cortex and the rostral anterior cingulate cortex during negative cue presentation than the other groups.

CONCLUSIONS

These results provide preliminary evidence of enhanced stress cue reactivity in individuals reporting co-use of alcohol and cannabis, particularly women co-users.

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

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

Alcohol subjective responses in heavy drinkers: Measuring acute effects in the natural environment versus the controlled laboratory setting

BACKGROUND

For decades, laboratory alcohol challenges have been the "gold standard" for measuring individual differences in alcohol's subjective effects. However, these approaches are expensive and labor-intensive, making them impractical for large-scale use. This study examined the reliability and validity of a new high-resolution EMA (HR-EMA) ambulatory approach to assessing alcohol use and subjective responses in drinkers' natural environments.

METHODS

Participants were 83 young adult heavy social drinkers (58% male; mean ± SD age = 25.4 ± 2.6 years) who completed up to two smartphone-based, 3-h HR-EMA assessments of alcohol use and related subjective responses in their typical drinking environments. Reported alcohol consumption during the HR-EMA periods was used to calculate estimated blood alcohol concentration (eBAC). Subjective effects were measured using the Brief Biphasic Alcohol Effects Scale (B-BAES) and Drug Effects Questionnaire (DEQ). All participants also completed identical measures during a separate, 4 to 5-h laboratory session in which they received a 0.8 g/kg alcohol challenge.

RESULTS

Most natural environment drinking episodes (87%) met or exceeded the threshold for binge drinking (final mean eBAC = 0.12 g/dl). Associations between reported alcohol use and subjective responses on the B-BAES and DEQ were strongest earlier in the drinking events, with fair reliability of reported subjective effects across two HR-EMA episodes (intraclass correlation [ICC] range = 0.46-0.49). There was fair-to-good correspondence between HR-EMA- and laboratory-derived subjective responses (ICC range = 0.49-0.74), even after accounting for differences in alcohol consumption and drinking context. Reported stimulating and rewarding alcohol effects were higher in the ambulatory than laboratory setting, and vice versa for sedating effects.

CONCLUSIONS

This study supports the reliability and validity of smartphone-based HR-EMA to measure alcohol use and subjective responses in heavy drinkers' natural environments. These findings lend support to the use of ambulatory HR-EMA as a measure of alcohol subjective responses in risky drinkers when a laboratory protocol is not practical, feasible, or safe.

Refining the marijuana purchase task: Using qualitative methods to inform measure development

Behavioral economic demand for cannabis (i.e., relative reinforcing value) can be measured via marijuana purchase tasks (MPTs). However, commodity ambiguities pose challenges and design concerns exist regarding current MPTs. The aim of this 2-phase study was to modify and improve a MPT using qualitative methods. Phase I: Focus groups were conducted with regular (i.e., average use ≥ once/week) cannabis users (n = 31; 6-7 per group M[SD] age = 26 [7]; 28% female). Focus groups followed a semistructured agenda, and executive summaries were made concerning key MPT themes. Feedback was used to refine the MPT. Phase II: Cognitive interviews using the refined MPT were conducted with regular cannabis users (n = 20; M[SD] age = 28 [8]; 50% female). Phase I: Focus group analyses highlighted 4 critical areas for MPT improvement: (a) unit of purchase, (b) cannabis quality, (c) time duration specified for use episode, and (d) price. Participants suggested using grams as the unit of purchase, tailoring cannabis quality to the individual, and clarifying intended episode length. Phase II: Cognitive interviewing indicated additional areas for task refinement, resulting in a second iteration of the MPT based on the 2 phases. Qualitative research in both phases suggested a number of substantive modifications to the MPT format. MPT modifications are expected to improve comprehension, ecological validity, and general construct validity. Findings highlight the importance of careful instructional set development for drug purchase tasks for heterogeneous products that do not have standard units of consumption. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Validity and measurement invariance of the Addictions Neuroclinical Assessment incentive salience domain among treatment-seekers with alcohol use disorder

Incentive salience, or the attribution of motivational value to stimuli, is a biopsychological process that is disrupted in alcohol use disorder (AUD). The Addictions Neuroclinical Assessment (ANA) is a framework to characterize heterogeneity in addiction and establish a common assessment battery for research and clinical use. The ANA framework hypothesizes three constructs that correspond to processes in the etiology, course, and treatment of addiction: incentive salience, negative emotionality, and executive function. The current study extends prior findings on the ANA by validating the incentive salience construct among participants (n = 563) in a multisite prospective study of individuals entering treatment for AUD. We used confirmatory factor analysis to test a one-factor model of incentive salience. Indicators included items assessing perception of urges to drink from the Alcohol Dependence Scale, Impaired Control Scale, and Marlatt Relapse Interview. Results indicated the one-factor model fit the data well (χ² (12) = 19.42, p = .08; RMSEA = 0.034 [90% CI: 0.000, 0.060], CFI = 0.992) and was measurement invariant across sex. Incentive salience was associated with drinking patterns (e.g., drinks per day, r = 0.447 [95% CI: 0.379, 0.514]); reasons for drinking (urges/temptation r = 0.529 [95% CI: 0.460, 0.599]); testing personal control, r = 0.384 (95% CI: 0.308, 0.461); social pressure, r = 0.549 (95% CI: 0.481, 0.617); and family history of AUD, r = 0.134. The incentive salience factor demonstrated greater predictive validity for drinking outcomes compared to alternative preexisting scales. Overall, this study provides support for the construct validity and measurement invariance of the ANA incentive salience construct in a sample of individuals seeking AUD treatment.

Translational dynamics of alcohol tolerance of preclinical models and human laboratory studies

Increasing sensitivity due to alcohol intake has been explored using molecular and cellular mechanisms of sensitization and adaptive biobehavioral changes as well as through negative experiences of altered function during withdrawal. However, within both a preclinical and human laboratory setting, little has been elucidated toward understanding the neural substrates of decreased sensitivity to alcohol effects, that is, alcohol tolerance. More paradigms assessing alcohol tolerance are needed. Tolerance can be assessed through both self-reported response (subjective) and observed (objective) measurements. Therefore, sensitivity to alcohol is an exploitable variable that can be utilized to disentangle the diverse alcohol use disorder (AUD) phenotypical profile. This literature review focuses on preclinical models and human laboratory studies to evaluate alcohol tolerance and its modulating factors. Increased understanding of alcohol tolerance has the potential to reduce gaps between preclinical models and human laboratory studies to better evaluate the development of alcohol-related biobehavioral responses. Furthermore, alcohol tolerance can be used as an AUD phenotypic variable in randomized clinical trials designed for developing AUD therapies. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Effects of Alcohol Cue Reactivity on Subsequent Treatment Outcomes Among Treatment-Seeking Individuals with Alcohol Use Disorder: A Multisite Randomized, Double-Blind, Placebo-Controlled Clinical Trial of Varenicline

BACKGROUND

The alcohol cue reactivity paradigm is increasingly used to screen medications for the treatment of alcohol use disorder (AUD) and other substance use disorders. Yet, its prospective association with craving and naturalistic drinking outcomes in clinical trials remains unknown. This study embedded repeated human laboratory assessments of alcohol cue reactivity within the context of a randomized controlled trial to examine the effects of varenicline tartrate (Chantix® ), a partial agonist of α4β2 nicotinic acetylcholine receptors, on alcohol craving among treatment-seeking heavy drinkers with AUD. Our main objectives were to test whether varenicline, as compared to placebo, blunts alcohol cue-elicited craving and test whether alcohol cue reactivity observed in the human laboratory predicts subsequent alcohol craving and use during the remainder of the trial.

DESIGN AND METHODS

This double-blind, randomized, 2-site study compared the effects of varenicline (up to 2 mg/d) and placebo on responses to in vivo alcohol cue and affective picture cue exposure in the human laboratory. Forty-seven volunteers (18 females, 29 males), ages 23 to 67 years (M = 43.7, SD = 11.5), were recruited from the community via advertisements to participate in a clinical trial designed to study the effects of varenicline on alcohol use. Participants were randomized to either varenicline or placebo for 6 weeks.

RESULTS

Varenicline did not attenuate cue-induced alcohol craving relative to placebo, but craving captured during the cue reactivity paradigm significantly predicted subsequent alcohol use in real-world settings during the clinical trial. Higher craving predicted heavier alcohol use.

CONCLUSIONS

Our results are among the first to show alcohol cue-induced craving captured during a human laboratory paradigm predicts drinking outcomes in the context of a clinical trial.

Preliminary evidence of different and clinically meaningful opioid withdrawal phenotypes

Opioid use disorder (OUD) is a public health crisis. Differences in opioid withdrawal severity that predict treatment outcome could facilitate the process of matching patients to treatments. This is a secondary analysis of a randomized controlled trial (RCT) that enrolled treatment seeking heroin-users (N = 89, males = 78) into a residential study. Participants maintained on morphine (30 mg, subcutaneous, four-times daily) underwent a naloxone (0.4 mg, IM = intramuscular) challenge session to precipitate withdrawal. Area-under-the-curve (AUC) values from self-reported withdrawal ratings during the challenge session were analyzed using K-means clustering, revealing two phenotype groups. Withdrawal and retention from the subsequent 14-day double-blind, double-dummy RCT comparing three study medications (clonidine, tramadol-ER, and buprenorphine) were evaluated as a function of phenotype. Cluster analyses suggested HIGH (N = 37; mean [SD] subjective opiate withdrawal scale [SOWS]-AUC 123.7 [65.8]) and LOW (N = 52; SOWS-AUC 68.0 [47.7]) withdrawal phenotype groups. HIGH participants were significantly more female and had lower body mass indices than LOW participants; no drug-use variables were significant. Regarding RCT outcomes, HIGH phenotype participants were less likely to be retained in the study (P = 0.02) and had higher mean self-reported withdrawal (P = 0.05) than LOW phenotype participants. A significant interaction in RCT retention was observed between phenotype (P = 0.02) and study medication (P < 0.01). Self-reported withdrawal was significant for phenotype (P = 0.02); study medication trended towards significance (P = 0.07). Results suggest patients have meaningfully different experiences of opioid withdrawal that may predict differential response to opioid pharmacotherapies during supervised withdrawal. Additional prospective research to replicate and more thoroughly evaluate withdrawal phenotype correlates and sex differences is warranted.

Mobile alcohol biosensors and pharmacotherapy development research

Recent advances in biosensor technology herald a major shift in the way alcohol use will be tracked in humans. Wearable biosensors can passively and continuously monitor wearers' alcohol consumption in real time. An important application of these biosensors is to improve the way medication for alcohol use disorder (AUD) is tested in clinical research. Both laboratory-based screening paradigms and clinical trials have methodological problems that impact their efficiency and predictive validity. Medication screening using laboratory-based methods is a resource-intensive assessment of a single episode of behavior in a non-representative setting. Clinical trials rely on participant self-report to document medication-induced changes in drinking behavior. This review describes how mobile biosensors can be leveraged to improve AUD medication development research. We first review the current state of alcohol biosensor technology with a focus on strengths and limitations of the devices. We describe how multiple biosensors can be combined to create a far more detailed record of drinking compared to single biosensor platforms. We then discuss each phase of the medication development pipeline in turn (i.e., phases 1-4) and describe how mobile biosensors can be incorporated in standard medication testing paradigms to improve efficiency and predictive validity. We conclude with discussion of challenges associated with using currently available biosensors for medication testing and recommendations for researchers wishing to incorporate alcohol biosensors into their own research.

Exposure to Stigma Elicits Negative Affect and Alcohol Craving Among Young Adult Sexual Minority Heavy Drinkers

BACKGROUND

Sexual orientation disparities in alcohol use disorder (AUD) are thought to be explained by stigma specific to sexual minorities. Despite the importance of negative affect and craving in addiction, research has yet to test the effects of stigma on affect and alcohol craving among sexual minorities. This laboratory study examined the effects of 3 novel mood inductions (stigma, general unpleasant, and neutral) on affect and alcohol craving among heavy-drinking sexual minority young adults. We also paired these mood inductions with an established alcohol cue reactivity paradigm to explore the effects of stigma on cue-elicited craving.

METHODS

Sexual minority participants (N = 20; 55% female), aged 18 to 27 years (M = 21.80, standard deviation = 2.65), were recruited from the community. Participants completed 3 mood induction and cue reactivity trials counterbalanced over 3 visits on different days: stigma, general unpleasant, and neutral mood inductions. A structured interview assessed criteria for DSM-5 AUD, and self-report measures assessed lifetime adverse experiences.

RESULTS

Most participants met criteria for past-year AUD (75%). Exposure to stigma produced more negative affect and greater alcohol craving than the neutral and general unpleasant mood induction conditions. The general unpleasant mood induction did not predict greater alcohol craving than the neutral mood induction. Stigma enhanced alcohol cue reactivity effects, as measured with a single-item craving measure, compared to the general unpleasant mood condition, and this effect remained significant while controlling for covariates.

CONCLUSIONS

Findings are the first to demonstrate how stigma uniquely predicts negative affect and alcohol craving among sexual minorities. This study suggests that being exposed to stigma, specifically heterosexism, elicits negative mood and alcohol craving among sexual minority young adults who are heavy drinkers.

The Interplay Between Subjective Response to Alcohol, Craving, and Alcohol Self-Administration in the Human Laboratory

BACKGROUND

Despite a rich literature on human laboratory paradigms of subjective response (SR) to alcohol, craving for alcohol, and alcohol self-administration, few studies have examined the interplay across these 3 constructs. The present study addresses this gap in the literature by examining the interplay between SR, craving, and self-administration in the human laboratory.

METHODS

Data were culled from a medication study (NCT02026011) in which heavy drinking participants of East Asian ancestry completed 2 double-blinded and counterbalanced experimental sessions. In each experimental session, participants received a priming dose of intravenous (IV) alcohol to a target breath alcohol concentration (BrAC) of 0.06 g/dl and measures of SR (stimulation and sedation) and alcohol craving were collected across rising BrACs. The IV alcohol challenge was immediately followed by a 1-hour alcohol self-administration period.

RESULTS

Mixed model analyses found a positive and significant relationship between the slope of stimulation and the slope of craving during the alcohol challenge. The relationship between sedation and craving, however, was not significant. The slope of craving during the alcohol challenge significantly predicted a higher number of mini-drinks consumed and lower latency to first drink. Further, mediation analyses found that craving was a significant mediator of the relationship between stimulation and total number of mini-drinks consumed, but the same pattern was not found for sedation.

CONCLUSIONS

Insofar as alcohol self-administration represents the end point of interest for a host of experimental and clinical research questions, the present study suggests that alcohol craving represents a more proximal predictor of self-administration than measures of alcohol-induced stimulation. It is recommended that human laboratory models interpret measures of SR and craving in light of their relative predictive utility for drinking outcomes.

Overcoming the "Valley of Death" in Medications Development for Alcohol Use Disorder

As the development of novel pharmacotherapies for alcohol use disorder (AUD) has been slow, the discovery and testing of more efficacious pharmacotherapies for AUD represent a high priority research area. In fact, the transition from preclinical to clinical testing of novel compounds has been termed the "valley of death" in medications development. One key obstacle consists of the lack of an articulated set of goals for each stage of medications development. Specifically, the knowledge outputs required to make the transition from safety testing, to early efficacy detection, to confirming clinical efficacy remain unclear, and this is despite a great deal of interest and substantial financial investment in developing novel therapeutics for AUD. This qualitative critical review seeks to draw parallels and lessons from the well-established stage model for behavioral therapies research with alcohol and other substance use disorders and to apply these insights into AUD pharmacotherapy development. We argue that human laboratory models and/or pilot randomized controlled trials should serve as intermediaries in the transition from preclinical studies to large, and costly, randomized controlled efficacy trials. The relative strengths and weaknesses of pilot clinical trials versus human laboratory studies for bridging the "valley of death" are discussed and explored via a Monte Carlo data simulation study. Multiple permutations of suitable research designs informed by the behavioral therapies development model are discussed with the overall goal of promoting consilience and maximizing efficiency across all phases of clinical testing of novel AUD pharmacotherapies.

Differences Between Treatment-Seeking and Nontreatment-Seeking Alcohol-Dependent Research Participants: An Exploratory Analysis

BACKGROUND

Alcoholism is a chronic relapsing disorder with complex behavioral and functional heterogeneity. To date, attempts to characterize subgroups of alcohol-dependent (AD) individuals have largely been focused on categorical distinctions based on behaviors such as ability to abstain, age of onset, and drinking motives, but these have failed to yield predictors of treatment response and disease course. The distinction between AD individuals who are or are not interested in treatment holds significant implications for interpreting results of human laboratory studies with nontreatment seekers and clinical trials with treatment-seeking AD patients. However, despite their crucial role in alcohol-related research, these 2 groups are poorly defined. In this exploratory analysis, we attempt to better define the phenotypic differences between these 2 experimentally relevant populations.

METHODS

We analyzed data from AD individuals who participated in screening protocols to evaluate their suitability for participation in either treatment or nontreatment research studies at NIAAA. Scores on individual measures from a battery of behavioral, neuropsychological, and blood laboratory measures were compared between those who presented seeking treatment for AD and those who were not seeking treatment. Differences in each measure were assessed between the 2 groups. In addition, we explored whether significant differences were apparent when drinking behavior was used as a covariate.

RESULTS

Treatment seekers manifested more impairment compared to nontreatment seekers on a wide variety of measures in the following categories: alcohol drinking, personality, impulsivity, trauma/stress, cognition, aggression, mood, and liver enzyme tests. Treatment seekers endorsed a greater number of AD criteria. Several measures including elevations in liver enzyme tests remained significantly different between the 2 groups when average daily alcohol consumption per drinking day was used as a covariate.

CONCLUSIONS

Treatment-seeking, compared to nontreatment-seeking AD subjects who present for alcohol-related research studies, differ in characteristics beyond the quantity of alcohol consumption. Implications of these differences with respect to clinical research for treatments of AD are discussed.

GRIK1 and GABRA2 Variants Have Distinct Effects on the Dose-Related Subjective Response to Intravenous Alcohol in Healthy Social Drinkers

BACKGROUND

The heritable risk for alcohol use disorder (AUD) is expressed partly through alterations in subjective alcohol response. In this study, we investigated the effects of 2 AUD-risk-associated single nucleotide polymorphisms, GABRA2 rs279858 and GRIK1 rs2832407, on the subjective response to alcohol administered intravenously to healthy social drinkers in a laboratory setting.

METHODS

In total, 93 self-identified European American social drinkers underwent 3 blinded laboratory sessions in which they received intravenous infusions of ethanol at 3 target blood alcohol levels (0.00 mg%, 40 mg%, and 100 mg%) using a "clamp" procedure. The self-reported Biphasic Alcohol Effects Scale (BAES) stimulation and sedation subscales were the primary outcome measures. We examined the effects of these 2 genetic variants on subjective response to alcohol.

RESULTS

For the BAES stimulation subscale scores, adjusting for age, baseline scores, and time effects, individuals with 2 copies of the GABRA2 rs279858 C "risk" allele for AUD exhibited the greatest stimulant responses to high-dose alcohol compared to the other risk allele counts (dose-by-allele count interaction effect, p = 0.001, post hoc contrast for C-allele, p = 0.012). For the BAES sedation subscale scores, adjusting for the same covariates, we detected a dose-by-allele count interaction effect (p = 0.0044) such that subjects with 2 copies of the GRIK1 C "risk" allele reported the greatest sedative response to the higher alcohol dose.

CONCLUSIONS

This study suggests that gene variants contributing to the risk for AUD may alter features of the alcohol dose-response relationship in specific ways. GABRA2 rs279858*C enhances stimulant responses to higher levels of alcohol, while the GRIK1 rs2832407*C-allele increases sedative responses. In summary, GRIK1 and GABRA2 variants have distinct effects on the dose-related subjective response to intravenous alcohol in humans.

Effects of naltrexone on alcohol self-administration and craving: meta-analysis of human laboratory studies

Randomized clinical trials have established the efficacy of naltrexone for reducing quantity of alcohol consumption and incidence of relapse to heavy drinking. To evaluate putative treatment mechanisms, human laboratory studies have examined naltrexone's effects on alcohol responses and self-administration during short-term medication protocols. Results from these studies are inconsistent and have yet to be examined in aggregate. This meta-analysis aimed to quantify naltrexone's effects on alcohol self-administration and craving in the context of placebo-controlled human laboratory trials. Potential moderators of medication effects were also examined. Meta-analyses of alcohol self-administration (k = 9, N = 490) and craving (k = 16, N = 748) confirmed that, under controlled experimental conditions, naltrexone reduces the quantity of consumption (Hedges' g = -.277, SE = .074, 95 percent CI = -.421, -.133, p < .001) and magnitude of self-reported craving (g = -.286, SE = .066, 95 percent CI = -.416, -.156, p < .001) relative to placebo. Subgroup and moderation analyses found no evidence that effect sizes differed by study population (dependent versus non-dependent drinkers), laboratory paradigm or duration of medication exposure. These results substantiate prior evidence for reductions in event-level craving and consumption as potential treatment mediators, also establishing effect sizes to inform future human laboratory trials. From a clinical perspective, these results may provide additional evidence regarding naltrexone's efficacy in the context of acute or subacute dosing regimens.

A Review of Developmental Considerations in Human Laboratory Alcohol Research

PURPOSE OF REVIEW

Human laboratory studies involving alcohol administration have generated critical knowledge about individual differences in risk for alcohol use disorder (AUD), but have primarily involved adult populations and cross-sectional research designs. Ethical constraints have largely precluded human laboratory alcohol research in adolescence, and prospective studies have been rare. This paper provides an overview of developmental considerations in human laboratory alcohol research, with a focus on studies conducted with youth.

RECENT FINDINGS

Recent human laboratory studies from Europe and Canada have examined aspects of alcohol response during late adolescence, while recent survey studies from the United States have highlighted methods for circumventing alcohol administration in studies of adolescents.

SUMMARY

Across several decades of research, exceedingly few laboratory studies have examined developmental differences in alcohol responses or utilized prospective designs. Efforts to prioritize prospective research would further clarify the role of alcohol sensitivity traits as predictors or markers of AUD onset and progression.

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

INTRODUCTION

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

METHOD

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

RESULTS

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

CONCLUSION

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

Medications development for the treatment of alcohol use disorder: insights into the predictive value of animal and human laboratory models

Development of effective treatments for alcohol use disorder (AUD) represents an important public health goal. This review provides a summary of completed preclinical and clinical studies testing pharmacotherapies for the treatment of AUD. We discuss opportunities for improving the translation from preclinical findings to clinical trial outcomes, focusing on the validity and predictive value of animal and human laboratory models of AUD. Specifically, while preclinical studies of medications development have offered important insights into the neurobiology of the disorder and alcohol's molecular targets, limitations include the lack of standardized methods and streamlined processes whereby animal studies can readily inform human studies. Behavioral pharmacology studies provide a less expensive and valuable opportunity to assess the feasibility of a pharmacotherapy prior to initiating larger scale clinical trials by providing insights into the mechanism of the drug, which can then inform recruitment, analyses, and assessments. Summary tables are provided to illustrate the wide range of preclinical, human laboratory, and clinical studies of medications development for alcoholism. Taken together, this review highlights the challenges associated with animal paradigms, human laboratory studies, and clinical trials with the overarching goal of advancing treatment development and highlighting opportunities to bridge the gap between preclinical and clinical research.

Differences between treatment-seeking and non-treatment-seeking participants in medication studies for alcoholism: do they matter?

BACKGROUND

Medication development for alcoholism typically includes experimental pharmacology studies with non-treatment-seeking individuals with alcohol use disorder (AUD) paving the way for randomized controlled trials in treatment-seekers with AUD.

OBJECTIVES

The goal of this study is to provide a direct comparison between AUD treatment-seeking research participants and non-treatment-seeking participants on demographic and clinical variables and to test whether variables that differentiate the two groups are associated with clinical outcomes.

METHOD

Non-treatment-seeking AUD participants (n = 213; 76.3% male) who completed behavioral pharmacology studies were compared to treatment-seekers who completed the COMBINE Study (n = 1383; 69.1% male) on demographic and clinical variables. Analyses examined whether the variables that differentiated the two groups predicted treatment outcomes in the COMBINE Study.

RESULTS

Analyses revealed that treatment-seeking participants were older, had more years of education, higher Alcohol Dependence Scale scores, higher Drinker Inventory of Consequences scores, higher Obsessive Compulsive Drinking Scale scores, a greater number of DSM-IV symptoms of AUD, longer duration of AUD, and consumed more standard drinks and more drinks per drinking day (i.e., in the past 30 days) compared to non-treatment-seeking participants. Nearly all characteristics that differed between the groups predicted at least one of the primary clinical outcomes of the COMBINE Study.

CONCLUSIONS

This study highlights a host of clinical and demographic factors that differ between non-treatment-seeking and treatment-seeking research participants and the clinical significance of these variables. Differences between samples should be considered and addressed in order to promote greater consilience across stages of medication development.

Biobehavioral effects of baclofen in anxious alcohol-dependent individuals: a randomized, double-blind, placebo-controlled, laboratory study

Baclofen has been suggested as a potential pharmacotherapy for alcohol use disorder, but the clinical data are conflicting. Here we investigated the biobehavioral effects of baclofen in a sample of anxious alcohol-dependent individuals. This was a randomized, double-blind, placebo-controlled, human laboratory study in non-treatment seeking alcohol-dependent individuals with high trait anxiety (N=34). Participants received baclofen (30 mg per day) or placebo for at least 8 days, then performed an experimental session consisting of alcohol cue-reactivity followed by alcohol administration procedure (alcohol priming, then alcohol self-administration). Total amount of alcohol self-administered was the primary outcome; alcohol craving, subjective/physiological responses and mood/anxiety symptoms were also evaluated. There was no significant medication effect on the total amount of alcohol consumed during the alcohol self-administration (P=0.76). Baclofen blunted the positive association between maximum breath alcohol concentration during priming and the amount of alcohol consumption (significant interaction, P=0.03). Ratings of feeling intoxicated were significantly higher in the baclofen group after consuming the priming drink (P=0.006). During the self-administration session, baclofen significantly increased ratings of feeling high (P=0.01) and intoxicated (P=0.01). A significant reduction in heart rate (P<0.001) and a trend-level increase in diastolic blood pressure (P=0.06) were also detected in the baclofen group during the alcohol laboratory session. In conclusion, baclofen was shown to affect subjective and physiological responses to alcohol drinking in anxious alcohol-dependent individuals. These results do not support an anti-craving or anti-reinforcing effect of baclofen, but rather suggest that baclofen may act as a substitution medication for alcohol use disorder.

Functional significance of subjective response to alcohol across levels of alcohol exposure

Pre-clinical neurobiological models of addiction etiology including both the allostatic model and incentive sensitization theory suggest that alcohol consumption among alcohol-dependent (AD) individuals will be dissociated from hedonic reward as positive reinforcement mechanisms wane in later stage dependence. The aims of this study are to test this claim in humans by examining the relationship between dimensions of subjective responses to alcohol (SR) and alcohol craving across levels of alcohol exposure. Non-treatment-seeking drinkers (n = 205) completed an i.v. alcohol challenge (final target breath alcohol concentration = 0.06 g/dl) and reported on SR and craving. Participants were classified as light-to-moderate drinkers (LMD), heavy drinkers (HD) or AD. Analyses examined group differences in SR and craving response magnitude, as well as concurrent and predictive associations between SR domains and craving. At baseline, LMD and AD reported greater stimulation than HD, which carried over post-alcohol administration. However, stimulation was dose-dependently associated with alcohol craving in HD only. Furthermore, lagged models found that stimulation preceded craving among HD only, whereas this hypothesized pattern of results was not observed for craving preceding stimulation. Sedation was also positively associated with craving, yet no group differences were observed. In agreement with the prediction of diminished positive reinforcement in alcohol dependence, this study showed that stimulation/hedonic reward from alcohol did not precede craving in AD, whereas stimulation was dose-dependently associated with and preceded craving among non-dependent HD.

Alcohol Craving and Consumption in Borderline Personality Disorder: When, Where, and with Whom

Substance use is highly prevalent in our society, and substance use disorders are comorbid with most psychiatric disorders, including borderline personality disorder (BPD; Grant et al., 2006, 2008). Craving is a fundamental feature of addiction and disorder, yet the contexts in which craving occurs and is associated with substance use is still under-researched. We examined alcohol craving and consumption in a sample of 56 BPD individuals and a comparison group of community drinkers (COM; n = 60) who carried electronic diaries for approximately 21 days. BPD individuals reported more craving than COM individuals in most contexts. Compared to COM individuals, elevated craving in BPD individuals was paralleled by more drinking when at work, at home, and with romantic partners, coworkers, and children. These findings identify contexts of particular relevance to those with BPD and other mood/anxiety disorders in which craving may lead to risky and maladaptive alcohol use.

Discovery, Development, and Adoption of Medications to Treat Alcohol Use Disorder: Goals for the Phases of Medications Development

For more than 25 years, advances have been made in developing medications to treat alcohol use disorder (AUD), highlighted by the U.S. Food and Drug Administration's approval of naltrexone (oral and long-acting) and acamprosate. Despite this progress, more work remains to be done in this area because these medications, although effective for some people, do not work for everyone. A high priority for the National Institute on Alcohol Abuse and Alcohol is to put into place a solid infrastructure to aid in the development of medications that are more effective than those currently available and with few side effects. Medication development, especially for a disorder as complex as AUD, is challenging and involves multiple phases, including discovery of "druggable" targets, preclinical studies, human clinical trials, and the adoption and implementation of the new medication into mainstream medicine. A successful medications development program requires clearly established goals for each phase to ensure that a candidate compound is not trapped in one particular phase, a condition known as "the valley of death." In this article, the phases of medication development are described as they apply to AUD, and specific goals of each phase are identified for the next decade. In addition, several important crosscutting themes are outlined for each phase, all of which are essential for advancing medications development. These include identifying and validating screening models and druggable targets, making use of precision medicine, and establishing partnerships among key stakeholders. Our goal in writing this article is to provide a guide on medications development that will aid the alcohol research community in planning, testing, and developing medications for AUD.

A Pilot Study of the Safety and Initial Efficacy of Ivermectin for the Treatment of Alcohol Use Disorder

BACKGROUND

Ivermectin (IVM) is an antiparasitic agent that has been shown to reduce alcohol intake in mice, suggesting IVM as a potential treatment for alcohol use disorder (AUD). However, the safety profile of IVM administered in combination with an intoxicating dose of alcohol has not been characterized in humans.

METHODS

This pilot project sought to provide the first clinical evidence that IVM could be repositioned as an AUD pharmacotherapy by examining (i) the safety of combining IVM (30 mg oral , once a day [QD]) with an intoxicating dose of intravenous alcohol (0.08 g/dl) and (ii) the effects of IVM on alcohol cue-induced craving and subjective response to alcohol. Eleven individuals with AUD participated in a randomized, placebo-controlled, crossover study in which they received the study medication, participated in a cue exposure paradigm followed by intravenous alcohol administration, and remained in an inpatient unit overnight for observation.

RESULTS

IVM treatment, versus placebo, did not increase the number or severity of adverse effects during alcohol administration or throughout the visit. However, IVM did not reduce cue-induced craving nor did it significantly affect subjective response to alcohol.

CONCLUSIONS

These results suggest that IVM (30 mg oral, QD) is safe in combination with an intoxicating dose of alcohol, but do not provide evidence that this dose of IVM is effective in reducing alcohol craving or its reinforcing effects. Given the preclinical data suggesting IVM is effective in reducing alcohol consumption in mice, additional studies testing larger samples and alternate dosing regimens are warranted to further characterize the potential efficacy of IVM as an AUD treatment.

Associations of OPRM1 A118G and alcohol sensitivity with intravenous alcohol self-administration in young adults

Human laboratory and animal models implicate variation in the μ-opioid receptor gene (OPRM1) as relevant for alcohol-related reward. OPRM1 is associated with alcohol self-administration in non-human primate studies, but the relevance of this finding to human models is unclear. This study used computer-assisted self-infusion of ethanol (CASE) to examine associations among OPRM1 A118G genotype, subjective responses to alcohol and intravenous alcohol self-administration in young heavy drinkers (n = 40, mean age = 19.95 years, SD = 0.82). Participants completed a 2-hour CASE session comprising a priming phase followed by ad libitum self-administration in a free-access paradigm. Participants achieved a mean peak breath alcohol concentration (BrAC) of 81.18 mg% (SD = 24.96). Those with the OPRM1 118G variant (GA or GG genotypes) achieved significantly higher peak BrAC (M = 94.90 mg%, SD = 16.56) than those with the AA genotype (M = 74.46 mg%, SD = 25.36), reflecting a significantly greater number of alcohol requests among GA/GG participants. Eighty percent of GA/GG participants surpassed a threshold defining a laboratory analog of heavy alcohol exposure (80 mg%) compared with 46 percent of AA participants. Results indicated significant associations between subjective measures of alcohol sensitivity and CASE outcomes, although the pattern of findings differed across self-report measures. Subjective responses did not differ by OPRM1 status. These results offer further support for the feasibility of the CASE paradigm and provide initial evidence for an association of OPRM1 with alcohol self-administration in a human laboratory context.

Further validation of a marijuana purchase task

BACKGROUND

A valid measure of the relative economic value of marijuana is needed to characterize individual variation in the drug's reinforcing value and inform evolving national marijuana policy. Relative drug value (demand) can be measured via purchase tasks, and demand for alcohol and cigarettes has been associated with craving, dependence, and treatment response. This study examined marijuana demand with a marijuana purchase task (MPT).

METHODS

The 22-item self-report MPT was administered to 99 frequent marijuana users (37.4% female, 71.5% marijuana use days, 15.2% cannabis dependent).

RESULTS

Pearson correlations indicated a negative relationship between intensity (free consumption) and age of initiation of regular use (r=-0.34, p<0.001), and positive associations with use days (r=0.26, p<0.05) and subjective craving (r=0.43, p<0.001). Omax (maximum expenditure) was positively associated with use days (r=0.29, p<0.01) and subjective craving (r=0.27, p<0.01). Income was not associated with demand. An exponential demand model provided an excellent fit to the data across users (R(2)=0.99). Group comparisons based on presence or absence of DSM-IV cannabis dependence symptoms revealed that users with any dependence symptoms showed significantly higher intensity of demand and more inelastic demand, reflecting greater insensitivity to price increases.

CONCLUSIONS

These results provide support for construct validity of the MPT, indicating its sensitivity to marijuana demand as a function of increasing cost, and its ability to differentiate between users with and without dependence symptoms. The MPT may denote abuse liability and is a valuable addition to the behavioral economic literature. Potential applications to marijuana pricing and tax policy are discussed.

Methods for inducing alcohol craving in individuals with co-morbid alcohol dependence and posttraumatic stress disorder: behavioral and physiological outcomes

Alcohol addiction is a chronic relapsing disorder that presents a substantial public health problem, and is frequently co-morbid with posttraumatic stress disorder (PTSD). Craving for alcohol is a predictor of relapse to alcohol use, and is triggered by cues associated with alcohol and trauma. Identification of reliable and valid laboratory methods for craving induction is an important objective for alcoholism and PTSD research. The present study compares two methods for induction of craving via stress and alcohol cues in individuals with co-morbid alcohol dependence (AD) and PTSD: the combined Trier social stress test and cue reactivity paradigm (Trier/CR), and a guided imagery (Scripts) paradigm. Outcomes include self-reported measures of craving, stress and anxiety as well as endocrine measures. Subjects were 52 individuals diagnosed with co-morbid AD and PTSD seeking treatment at the National Institute on Alcohol Abuse and Alcoholism inpatient research facility. They participated in a 4-week inpatient study of the efficacy of a neurokinin 1 antagonist to treat co-morbid AD and PTSD, and which included the two challenge procedures. Both the Trier/CR and Scripts induced craving for alcohol, as well as elevated levels of subjective distress and anxiety. The Trier/CR yielded significant increases in adrenocorticotropic hormone and cortisol, while the Scripts did not. Both paradigms are effective laboratory means of inducing craving for alcohol. Further research is warranted to better understand the mechanisms behind craving induced by stress versus alcohol cues, as well as to understand the impact of co-morbid PTSD and AD on craving.

Long-term behavioral impairment following acute embryonic ethanol exposure in zebrafish

BACKGROUND

Developmental exposure to ethanol has long been known to cause persisting neurobehavioral impairment. However, the neural and behavioral mechanisms underlying these deficits and the importance of exposure timing are not well-characterized. Given the importance of timing and sequence in neurodevelopment it would be expected that alcohol intoxication at different developmental periods would result in distinct neurobehavioral consequences.

METHODS

Zebrafish embryos were exposed to ethanol (0%, 1%, 3%) at either 8-10 or 24-27 h post-fertilization (hpf) then reared to adolescence and evaluated on several behavioral endpoints. Habituation to a repeated environmental stimulus and overall sensorimotor function were assessed using a tap startle test; measurements of anxiety and exploration behavior were made following introduction to a novel tank; and spatial discrimination learning was assessed using aversive control in a three-chambered apparatus. Overt signs of dysmorphogenesis were also scored (i.e. craniofacial malformations, including eye diameter and midbrain-hindbrain boundary morphology).

RESULTS

Ethanol treated fish were more active both at baseline and following a tap stimulus compared to the control fish and were hyperactive when placed in a novel tank. These effects were more prominent following exposure at 24-27 hpf than with the earlier exposure window, for both dose groups. Increases in physical malformation were only present in the 3% ethanol group; all malformed fish were excluded from behavioral testing.

DISCUSSION

These results suggest specific domains of behavior are affected following ethanol exposure, with some but not all of the tests revealing significant impairment. The behavioral phenotypes following distinct exposure windows described here can be used to help link cellular and molecular mechanisms of developmental ethanol exposure to functional neurobehavioral effects.

Craving and subjective responses to alcohol administration: validation of the desires for alcohol questionnaire in the human laboratory

OBJECTIVE

The abbreviated Desires for Alcohol Questionnaire (DAQ) is a self-report assessment of craving comprising the following subscales: (a) strong desires/intentions to drink, (b) negative reinforcement, and (c) positive reinforcement and ability to control drinking. Although the DAQ is sensitive to changes in alcohol craving precipitated by alcohol administration and/or cue exposure, no studies to date have examined the relationship between DAQ scores and subjective responses to alcohol. This study addresses this gap in the literature by testing the relationship between subjective responses to alcohol during alcohol administration and DAQ scores assessed 1 month later.

METHOD

Individuals with alcohol dependence (n = 32) completed a randomized, single-blinded, intravenous alcohol administration in the laboratory in which subjective responses to the alcohol were measured, followed by a visit to the laboratory 1 month later to complete the DAQ.

RESULTS

Analyses revealed robust associations between DAQ scores and alcohol craving during alcohol administration (partial correlations: r = .43-.50, ps < .01), with the exception of the positive reinforcement subscale (r = .20, p = .30). Subjective intoxication and sedation were only associated with the negative reinforcement subscale of the DAQ (r = .38, p < .05 and r = .33, p < .05, respectively).

CONCLUSIONS

Craving, captured by the DAQ, is reliably and positively associated with alcohol-induced craving. The DAQ is also associated with specific dimensions of subjective responses to alcohol. These results support the clinical utility of the DAQ, particularly in large samples where experimental manipulations may not be feasible.

Opportunities for the development of neuroimmune therapies in addiction

Studies have implicated neuroinflammatory processes in the pathophysiology of various psychiatric conditions, including addictive disorders. Neuroimmune signaling represents an important and relatively poorly understood biological process in drug addiction. The objective of this review is to update the field on recent developments in neuroimmune therapies for addiction. First, we review studies of neuroinflammation in relation to alcohol and methamphetamine dependence followed by a section on neuroinflammation and accompanying neurocognitive dysfunction in HIV infection and concomitant substance abuse. Second, we provide a review of pharmacotherapies with neuroimmune properties and their potential development for the treatment of addictions. Pharmacotherapies covered in this review include ibudilast, minocycline, doxycycline, topiramate, indomethacin, rolipram, anakinra (IL-1Ra), peroxisome proliferator-activated receptor agonists, naltrexone, and naloxone. Lastly, summary and future directions are provided with recommendations for how to efficiently translate preclinical findings into clinical studies that can ultimately lead to novel and more effective pharmacotherapies for addiction.

Effects of the opioid receptor antagonist naltrexone on smoking and related behaviors in smokers preparing to quit: a randomized controlled trial

AIMS

To determine if naltrexone affects smoking behaviors in smokers preparing to quit, and whether or not such pre-quit responses predict post-quit date outcomes.

DESIGN

Double-blind, placebo-controlled, randomized study. The current study focused on smoking-related outcomes in the pre-quit phase, which was 1 week prior to the quit date, and these findings were linked with reductions in the same outcomes demonstrated in the post-quit phase published previously for this randomized controlled trial (RCT) in mediation analyses.

SETTING

Community sample of adult smokers desiring to quit in Chicago, Illinois, USA.

PARTICIPANTS

Participants were 315 smokers randomized to naltrexone (n = 161; mean age = 42.58 years; 60% Caucasian) or placebo (n = 154; mean age = 41.32 years; 55% Caucasian).

MEASUREMENTS

The difference from baseline in the number of cigarettes smoked during the pre-quit phase interval was the primary outcome. Secondary pre-quit outcomes were assessed using Likert scales of subjective responses and consumption of cigarettes, alcohol and food. Number of cigarettes smoked, alcoholic drinks consumed and the Brief Questionnaire of Smoking Urges were assessed in the post-quit phase.

FINDINGS

Relative to placebo, naltrexone decreased the number of cigarettes smoked (-4.21 versus -2.93, P < 0.05), smoking urge (P = 0.02) and number of alcoholic drinks consumed (P = 0.04). Exploratory mediation analyses linking outcomes of the pre-quit and post-quit phases found that naltrexone's effects on reducing smoking urge, cigarettes smoked and alcoholic drinks consumed in the pre-quit phase demonstrated full mediation of their respective effects during the post-quit phase.

CONCLUSIONS

Naltrexone taken in the week before a quit attempt reduces cigarette consumption, urges to smoke and alcohol consumption relative to placebo. The size of the effect mediates statistically the size of similar effects after the quit date.

Alcohol use following an alcohol challenge and a brief intervention among alcohol-dependent individuals

BACKGROUND AND OBJECTIVES

The study examined the effects of an alcohol challenge on naturalistic drinking among alcohol-dependent individuals and explored brief motivational interviewing (MI) as a potential intervention for these participants.

METHOD

Alcohol-dependent individuals (n = 32, eight females) completed the intake assessment, alcohol challenge, one MI session, and 1-month follow-up (87.5% retention) where they completed measures of drinking and motivation for change.

RESULTS

As expected, multilevel mixed models revealed that drinking did not increase post-alcohol challenge. Participants reported a reduction in ambivalence, drinking days, and a trend towards fewer total drinks between the MI and 1-month follow-up.

CONCLUSIONS

Consistent with other studies, the alcohol challenge did not worsen alcohol use. Results support further investigation of brief MI for alcohol-dependent participants in alcohol challenges.

SCIENTIFIC SIGNIFICANCE

Alcohol administration to alcohol-dependent participants appears to not exacerbate naturalistic drinking. MI may be a feasible intervention for non-treatment seeking alcohol-dependent participants in alcohol challenge studies.