Factor Structure of Subjective Responses to Alcohol in Light and Heavy Drinkers

Use of mindfulness training to improve BAC self-estimation during a drinking episode

OBJECTIVE

Individuals are often inaccurate at estimating levels of intoxication following doses of alcohol. Previous research has shown that when required to estimate (BAC) at different time points, participants often underestimate their BACs and amounts of alcohol consumed. The present study aimed to increase drinkers' BAC estimation accuracy after drinking alcohol using mindfulness-based feedback to increase their awareness of the interoceptive cues associated with alcohol intoxication.

METHOD

Thirty-three adults were given 0.65 g/kg of alcohol and received one of three training conditions: BAC feedback only, body scan exercise + BAC feedback and no treatment control. Those in the BAC feedback group received feedback concerning their observed BAC during dose exposure. Participants in the body scan group received BAC feedback and underwent a mindfulness exercise to enhance their perception of the acute subjective effects of alcohol. The control group received no BAC estimation training. Participants attended four study sessions: Two training sessions where participants underwent structured training based on their condition and two retention sessions to test for the lasting effects of the training exercises.

RESULTS

Retention tests showed that participants in both treatment groups were most accurate in estimating their BACs. There were no differences among the groups in their perceived levels of intoxication at posttraining. The findings suggest that BAC feedback, alone and in combination with, mindfulness training can improve accuracy in estimating BACs.

CONCLUSIONS

The findings provide preliminary support for the efficacy of mindfulness training in combination with BAC feedback to improve BAC estimation accuracy. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Slow Drinking of Beer Attenuates Subjective Sedative Feeling in Healthy Volunteers: A Randomized Crossover Pilot Study

The change in physiological parameters and subjective feelings according to the speed of drinking alcohol has not been reported to date. The aim of this randomized crossover pilot study was to investigate the objective and subjective effects of different speeds of alcohol ingestion in healthy volunteers. Accordingly, 11 male and 7 female healthy Japanese adults were asked to consume 480 mL of beer at three different drinking speeds (80, 40, and 20 mL/5 min). According to the objective measurement, the transient increase in blood alcohol and serum uric acid concentrations was most inhibited at a drinking speed of 20 mL/5 min. Acetate, lactate, pyruvate, and lactate/pyruvate ratios did not differ between the three drinking speeds. Stimulant feelings measured by the subjective scores of the Brief Biphasic Alcohol Effects Scale did not differ between the three speeds. However, the sedative feeling score obtained at a drinking speed of 20 mL/5 min (the slowest speed of alcohol consumption) was significantly weakened in comparison with those obtained at drinking speeds of 40 and 80 mL/5 min. Therefore, a slower consumption of alcohol mitigated the subjective sedative feeling. The effects of slower alcohol consumption may be caused by the slower slope of the increasing trend of blood alcohol concentration.

Cannabis use and subjective response to alcohol in the human laboratory

BACKGROUND

Cannabis is often used in combination with alcohol; yet, whether cannabis use impacts risk factors for alcohol use disorder (AUD) remains unknown. Subjective response (SR) to alcohol represents a biobehavioral risk factor for subsequent heavy drinking and for developing AUD. Given the high prevalence of alcohol and cannabis co-use, it is plausible to hypothesize that cannabis users differ in SR to alcohol compared to non-cannabis users. The purpose of this study is to examine the influence of past-month cannabis use on subjective response to alcohol in the human laboratory.

METHODS

This study culled data from multiple alcohol administration trials to test whether cannabis users, compared to non-cannabis users, differed in subjective response to alcohol, comprised of four domains: stimulation, sedation, negative affect, and craving. Non-treatment-seeking heavy drinkers (N = 168) completed a battery of self-report scales of mood and alcohol/cigarette/cannabis use and problems. All participants completed an intravenous alcohol administration session wherein SR domains were measured at the following breath alcohol concentrations (BrAC): baseline (i.e., 0), 20, 40, and 60 mg%.

RESULTS

Multilevel statistical analyses revealed that cannabis users had a greater reduction in negative affect during alcohol administration, compared to non-cannabis users. No significant differences were found for the other SR domains.

CONCLUSIONS

Using a large sample and advanced data analytic methods, this study extends the literature by suggesting that cannabis users are more sensitive to alcohol-induced reductions in negative affect compared to non-cannabis users. This work extends research on how cannabis use may influence risk factors for AUD, such as subjective response to alcohol.

Acute alcohol rewarding effects as a risk factor for hangover frequency

BACKGROUND/PURPOSE

Acute subjective alcohol effects appear to play an important role in predicting alcohol hangover. However, no studies have used a laboratory-based alcohol challenge to examine the concurrent or longitudinal effects of subjective alcohol responses on hangover frequency. As such, we investigated the direct and indirect effects of alcohol stimulation, sedation, liking and wanting, as measured in a controlled setting, on hangover frequency over five years.

METHOD

Participants were 294 young adult light-to-heavy social drinkers (aged 21-35 years, 42% female) enrolled in the Chicago Social Drinking Project. The study utilized a placebo-controlled, double blind, laboratory alcohol challenge and a battery of measures including the Biphasic Alcohol Effects Scale, Drug Effects Questionnaire, Hangover Symptom Scale, and alcohol use Quantity-Frequency Interview, with the latter two re-administered after five years.

RESULTS

Through the use of a path analysis, the present study found significant direct effects from alcohol liking to hangover frequency at initial testing. In addition, there were multiple significant indirect effects from greater alcohol liking and wanting to greater alcohol use quantity-frequency and, in turn, greater hangover frequency at initial testing and 5-year follow-up. Last, there were significant indirect effects from greater alcohol sedation to less alcohol use quantity-frequency and, in turn, less hangover frequency at initial testing and 5-year follow-up.

CONCLUSION

This study highlights the role of the hedonic reward and motivational salience of alcohol as potential mechanisms of alcohol-related consequences (i.e., hangover) among light-to-heavy social drinking young adults.

Moderators of subjective response to alcohol in the human laboratory

BACKGROUND

Subjective response (SR) to alcohol represents a biobehavioral risk factor for heavy drinking and for developing alcohol use disorder (AUD). Identifying moderators of SR have been hindered by small sample sizes that are often used in alcohol administration studies.

METHODS

This study combined data from multiple alcohol administration trials to test whether sex, family history of alcohol problems, and impulsivity (via delay discounting) predict SR to alcohol, comprised of four domains: stimulation, sedation, negative affect, and craving. Non-treatment-seeking heavy drinkers (N = 250) completed a battery of self-report scales and behavioral measures of alcohol use and problems, mood, and impulsivity. All participants completed an intravenous alcohol administration session wherein SR domains were measured at baseline, 20, 40, and 60 mg%.

RESULTS

Analyses using multilevel modeling showed that male sex independently predicted higher alcohol-induced stimulation and alcohol craving, after controlling for other moderators. A family history of alcohol problems also independently predicted alcohol craving after controlling for other moderators.

CONCLUSIONS

Using a large sample and advanced data analytic methods, this study extends the literature on alcohol administration by identifying important moderators of SR in heavy drinkers: namely, male sex and family history of alcohol problems. These findings consolidate and extend a growing body of research aimed at differentiating individuals most likely to report the SR features that confer risk for AUD.

Subjective alcohol responses in high- and low-risk adolescents: results from the Dresden Longitudinal Study on Alcohol Use in Young Adults

BACKGROUND AND AIMS

Research shows that sensitivity to certain alcohol responses conveys risk for problem drinking. This study aimed to determine if high-risk adolescent drinkers infuse more alcohol and experience greater alcohol-induced stimulation and wanting and less sedation than low-risk adolescent drinkers.

DESIGN AND PARTICIPANTS

Ninety-two low- (n = 38) and high-risk (n = 54) adolescent drinkers, as determined by Alcohol Use Disorders Identification Test scores of < 6 or ≥ 6, respectively, participated in the Dresden Longitudinal Study on Alcohol Use in Young Adults in which intravenous alcohol self-administration was examined in a mixed within- and between-subjects design.

SETTING

Technische Universität Dresden. Dresden, Germany.

MEASUREMENTS

Predictors were drinking status (high- versus low-risk), time and their interactions. Outcomes were arterial blood alcohol concentration (aBAC); alcohol-induced stimulation, sedation and wanting assessed at baseline, 10 (alcohol prime), 45, 65, 85, 105, 125 and 145 minutes. Covariates were family history of alcohol use disorder, sex and aBAC.

RESULTS

The alcohol prime dose produced similar sharp increases in stimulation and sedation in high- and low-risk drinkers (time P < 0.001; group × time P > 0.05). During self-administration, high-risk drinkers reached higher aBACs (P = 0.028) at a faster rate (group × time P < 0.001), and experienced further increases in stimulation (group × time P = 0.005) but with similar sedation (group × time P = 0.794) than in low-risk drinkers. High-risk drinkers also exhibited greater tonic alcohol wanting (group P = 0.003) throughout the session.

CONCLUSIONS

High-risk adolescent drinkers appear to have heightened sensitivity to alcohol-induced stimulation and tonic high levels of wanting compared with low-risk adolescent drinkers.

A meta-regression of methodological features that predict the effects of medications on the subjective response to alcohol

BACKGROUND

Alcohol administration paradigms have been used for early efficacy testing of novel compounds for alcohol use disorder (AUD). There has been an ongoing debate about sample characteristics and methodological features that affect the likelihood of detecting an early efficacy signal for AUD medications. We conducted a meta-regression to test whether the drinking level of the study sample and the peak breath alcohol concentration (BrAC) in the alcohol administration study predict the efficacy of AUD pharmacotherapies on the subjective responses to alcohol.

METHODS

We computed the effects of 21 medications on alcohol-induced stimulation, sedation, negative mood, and craving during alcohol administration in 49 studies.

RESULTS

Meta-regression analyses indicated a significant and positive effect of pre-study drinks per month on alcohol-induced stimulation (β = 0.142, p < 0.0001), such that as drinking increases, the benefit of medication over placebo decreases. There was an effect of drinks per month on negative mood (β = -0.164, p = 0.0248), such that at higher levels of drinks per month, the effects of medications on negative mood are stronger. For sedation, there was an effect of peak BrAC (β = 0.119, p = 0.0002), such that at low levels of peak BrAC, the effects of medication on sedation were null. For craving, there was a peak BrAC × drinks per month interaction such that at low levels of BrAC, a heavier drinking sample is required to detect the effects of medication on craving. Sensitivity analyses comparing naltrexone studies and non-naltrexone studies suggested that naltrexone was less sensitive to drinks per month across subjective response domains.

CONCLUSIONS

These analyses show that design features are critical in studies that test the effects of medications on the subjective responses to alcohol. By specifying the significance and directionality of these effects, as well as the specific points in BrAC or drinks per month at which medication effects are detectable, the study offers recommendations for design features of alcohol administration studies that aim to inform AUD medication development.

Modeling motivation for alcohol in humans using traditional and machine learning approaches

Given the significant cost of alcohol use disorder (AUD), identifying risk factors for alcohol seeking represents a research priority. Prominent addiction theories emphasize the role of motivation in the alcohol seeking process, which has largely been studied using preclinical models. In order to bridge the gap between preclinical and clinical studies, this study examined predictors of motivation for alcohol self-administration using a novel paradigm. Heavy drinkers (n = 67) completed an alcohol infusion consisting of an alcohol challenge (target breath alcohol = 60 mg%) and a progressive-ratio alcohol self-administration paradigm (maximum breath alcohol 120 mg%; ratio requirements range = 20-3 139 response). Growth curve modeling was used to predict breath alcohol trajectories during alcohol self-administration. K-means clustering was used to identify motivated (n = 41) and unmotivated (n = 26) self-administration trajectories. The data were analyzed using two approaches: a theory-driven test of a-priori predictors and a data-driven, machine learning model. In both approaches, steeper delay discounting, indicating a preference for smaller, sooner rewards, predicted motivated alcohol seeking. The data-driven approach further identified phasic alcohol craving as a predictor of motivated alcohol self-administration. Additional application of this model to AUD translational science and treatment development appear warranted.

Do behavioral pharmacology findings predict clinical trial outcomes? A proof-of-concept in medication development for alcohol use disorder

Behavioral pharmacology paradigms have been used for early efficacy testing of novel compounds for alcohol use disorder (AUD). However, the degree to which early efficacy in the human laboratory predicts clinical efficacy remains unclear. To address this gap in the literature we employed a novel meta-analytic approach. We searched the literature for medications tested for AUD using both behavioral pharmacology (i.e., alcohol administration) and randomized clinical trials (RCTs). For behavioral pharmacology, we computed medication effects on alcohol-induced stimulation, sedation, and craving during the alcohol administration (k = 51 studies, 24 medications). For RCTs, we computed medication effects on any drinking and heavy drinking (k = 118 studies, 17 medications). We used medication as the unit of analysis and applied the Williamson-York bivariate weighted least squares estimation to preserve the errors in both the independent and dependent variables. Results, with correction for publication bias, revealed a significant and positive relationship between medication effects on alcohol-induced stimulation (β = 1.18 p < 0.05), sedation (β = 2.38, p < 0.05), and craving (β = 3.28, p < 0.001) in the laboratory, and drinking outcomes in RCTs, such that medications that reduced stimulation, sedation, and craving during the alcohol administration were associated with better clinical outcomes. A leave-one-out Monte Carlo analysis examined the predictive utility of these laboratory endpoints for each medication. The observed clinical effect size was within one standard deviation of the mean predicted effect size for all but three pharmacotherapies. This proof-of-concept study demonstrates that behavioral pharmacology endpoints of alcohol-induced stimulation, sedation, and craving track medication effects from the human laboratory to clinical trial outcomes. These results apply to alcohol administration phenotypes and may be especially useful to medications for which the mechanisms of action involve alterations in subjective responses to alcohol (e.g., antagonist medication). These methods and results can be applied to a host of clinical questions and can streamline the process of screening novel compounds for AUD. For instance, this approach can be used to quantify the predictive utility of cue-reactivity screening models and even preclinical models of medication development.

Systems genetics analysis of the LXS recombinant inbred mouse strains:Genetic and molecular insights into acute ethanol tolerance

We have been using the Inbred Long- and Short-Sleep mouse strains (ILS, ISS) and a recombinant inbred panel derived from them, the LXS, to investigate the genetic underpinnings of acute ethanol tolerance which is considered to be a risk factor for alcohol use disorders (AUDs). Here, we have used RNA-seq to examine the transcriptome of whole brain in 40 of the LXS strains 8 hours after a saline or ethanol "pretreatment" as in previous behavioral studies. Approximately 1/3 of the 14,184 expressed genes were significantly heritable and many were unique to the pretreatment. Several thousand cis- and trans-eQTLs were mapped; a portion of these also were unique to pretreatment. Ethanol pretreatment caused differential expression (DE) of 1,230 genes. Gene Ontology (GO) enrichment analysis suggested involvement in numerous biological processes including astrocyte differentiation, histone acetylation, mRNA splicing, and neuron projection development. Genetic correlation analysis identified hundreds of genes that were correlated to the behaviors. GO analysis indicated that these genes are involved in gene expression, chromosome organization, and protein transport, among others. The expression profiles of the DE genes and genes correlated to AFT in the ethanol pretreatment group (AFT-Et) were found to be similar to profiles of HDAC inhibitors. Hdac1, a cis-regulated gene that is located at the peak of a previously mapped QTL for AFT-Et, was correlated to 437 genes, most of which were also correlated to AFT-Et. GO analysis of these genes identified several enriched biological process terms including neuron-neuron synaptic transmission and potassium transport. In summary, the results suggest widespread genetic effects on gene expression, including effects that are pretreatment-specific. A number of candidate genes and biological functions were identified that could be mediating the behavioral responses. The most prominent of these was Hdac1 which may be regulating genes associated with glutamatergic signaling and potassium conductance.

An Exploratory Factor Analysis of the Stimulant, Sedative, and Affective Responses to Alcohol

BACKGROUND

Subjective response (SR) to acute alcohol reflects individual variance to the sensitivity of alcohol's pharmacological effects. It has been argued that measures of stimulation and sedation may not fully capture the full-range SR, with 2 novel domains proposed: high arousal negative and low arousal positive. While substantial progress has been made in the field of SR and alcohol use risk, it remains unknown how these novel domains correspond to traditional SR measures. Therefore, the current study examined the latent structure of traditional and novel SR measures at rising breath alcohol concentrations (BrACs) during alcohol administration.

METHODS

Heavy drinkers (n = 67; 36M/31F) participated in an intravenous alcohol administration. Questionnaires assessing stimulation, sedation, mood, valence and arousal, and craving were assessed at baseline and at BrACs of 20, 40, and 60 mg%. A series of exploratory factor analyses were conducted to examine the latent factor structure of SR at each time point. Correlations examined the association between the generated factors and measures of problematic alcohol use.

RESULTS

The analysis generated a 3-factor solution, consistent across all time points. The factors measured the following effects of SR: (i) stimulation and positive mood, (ii) sedation and aversive effects, and (iii) tension reduction. The tension reduction factor was most commonly associated with problematic alcohol use in this sample.

CONCLUSION

This study extends upon the literature evaluating the biobehavioral effects of alcohol by examining a novel combination of SR to alcohol measures. This study demonstrates that the proposed low arousal positive domain, which loaded onto the tension reduction factor, provides novel information not captured by previous SR measures. Going forward, studies of alcohol's subjective effects should use this dimensional approach to reduce multiple comparisons across a wide range of scales and to build a literature grounded on the underlying structure of SR as a translational phenotype for AUD.

Reward, Relief and Habit Drinking: Initial Validation of a Brief Assessment Tool

AIMS

Alcohol use disorder is highly heterogeneous. One approach to understanding this heterogeneity is the identification of drinker subtypes. A candidate classification consists of reward and relief subtypes. The current study examines a novel self-report measure of reward, relief, and habit drinking for its clinical correlates and subjective response (SR) to alcohol administration.

METHODS

Non-treatment-seeking heavy drinkers (n = 140) completed the brief reward, relief, habit drinking scale (RRHDS). A subset of this sample (n = 67) completed an intravenous alcohol administration. Individuals were classified into drinker subtypes. A crowdsourced sample of heavy drinkers (n = 187) completed the RRHDS and a validated reward relief drinking scale to compare drinking classification results.

RESULTS

The majority of the sample was classified as reward drinkers (n = 100), with fewer classified as relief (n = 19) and habit (n = 21) drinkers. Relief and habit drinkers reported greater tonic alcohol craving compared to reward drinkers. Reward drinkers endorsed drinking for enhancement, while relief drinkers endorsed drinking for coping. Regarding the alcohol administration, the groups differed in negative mood, such that relief/habit drinkers reported a decrease in negative mood during alcohol administration, compared to reward drinkers. The follow-up crowdsourcing study found a 62% agreement in reward drinker classification between measures and replicated the tonic craving findings.

CONCLUSIONS

Our findings suggest that reward drinkers are dissociable from relief/habit drinkers using the brief measure. However, relief and habit drinkers were not successfully differentiated, which suggests that these constructs may overlap phenotypically. Notably, measures of dysphoric mood were better at detecting group differences than measures capturing alcohol's rewarding effects.

Alcohol Tolerance in Human Laboratory Studies for Development of Medications to treat Alcohol Use Disorder

AIMS

Human laboratory studies have contributed extensively in the research and development of novel medications to treat alcohol use disorder (AUD). Alcohol tolerance may represent one additional variable that can be utilized to expand the understanding of the AUD wide phenotypic profile and provide support to the medication development process. Tolerance is characterized as an individual's subjective response to alcohol and has been recognized as a predictor of AUD progression. Tolerance can be evaluated both by self-reported response (e.g. assessments) and objective measurements (e.g. motor impairment); as such, it represents an exploitable variable in the field of alcohol research.

METHODS

This Narrative Review focuses on the use of alcohol tolerance, specifically within alcohol laboratory studies, for medication development. It seeks to identify a research gap and a research opportunity in clinical studies to evaluate biobehavioral responses captured in order to develop medications to treat AUD.

RESULTS

Alcohol tolerance may provide additional information on the safety and tolerability of medications to treat AUD, in particular, when novel medications are co-administered with alcohol within the AUD population.

CONCLUSIONS

As such, alcohol tolerance represents an additional outcome that may be included in randomized clinical trial (RCT) protocols designed for developing AUD pharmacotherapies.

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

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

Naltrexone effects on subjective responses to alcohol in the human laboratory: A systematic review and meta-analysis

Naltrexone (NTX) has been widely studied for the treatment of alcohol use disorder with overall support for its efficacy. The mechanisms of action of naltrexone are thought to involve attenuation of the hedonic effects of alcohol and potentiation of its aversive effects. In order to provide a quantitative estimate of the effects of naltrexone on subjective response to alcohol, the aims of this meta-analytic review are to examine the effects of naltrexone across four domains of subjective response. Meta-analyses of naltrexone effects on alcohol craving (k = 16, N = 686), stimulation (k = 15, N = 675), sedation (k = 18, N = 777), and negative mood (k = 9, N = 281) suggested that under laboratory conditions and compared with placebo, naltrexone reduces craving (Hedges g = -0.252; SE = 0.054; 95% CI, -0.375 to -0.130; P < 0.01), reduces stimulation (g = -0.223; SE = 0.067; 95% CI, -0.372 to -0.074; P < 0.01), increases sedation (g = 0.251; SE = 0.064; 95% CI, 0.112-0.389; P < 0.01), and increases negative mood (g = 0.227; SE = 0.047; 95% CI, 0.100-0.354; P < 0.01). Results were robust when drinks per month and alcohol dose were added to the models as covariates. The effects of naltrexone varied by severity of alcohol use with medication effects on craving and stimulation being observed in sample of both heavy drinkers and AUD individuals. These results are consistent with the hypothesized mechanisms of action of NTX, although the effects are of small magnitude. This meta-analysis aggregates across multiple human laboratory studies of NTX's effects on subjective response to alcohol, providing a comprehensive summary of a key mechanism of NTX efficacy, namely, alteration of the subjective experience of alcohol.

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.

Interactions between TLR4 methylation and alcohol consumption on subjective responses to an alcohol infusion

Aims

Converging evidence has implicated perturbed inflammatory signaling in alcohol use disorders (AUDs), and both animal and human studies suggest that alcohol-induced inflammatory signaling is mediated by Toll-Like Receptor 4 (TLR4). We previously demonstrated that TLR4 is hypermethylated in subjects with AUD compared to control individuals. Examining the relationship between TLR4 methylation and subjective alcohol responses could shed light on the role of TLR4 in promoting AUDs, thereby highlighting its potential as a treatment target.

Short summary

Significant interactions were demonstrated between Toll-like Receptor 4 (TLR4) methylation and human alcohol consumption patterns, such that greater methylation was associated with decreased positive and negative self-reported arousal during an alcohol infusion among light-to-moderate drinkers, but increased self-reported positive arousal and physiological arousal (i.e. systolic blood pressure) among heavy drinkers.

Methods

Latent growth models were used to examine the relationship between TLR4 methylation and subjective responses and physiological measures of arousal during an alcohol infusion across 222 drinkers.

Results

We observed significant interactions of TLR4 methylation and alcohol use (drinks per week) on intercepts for self-report and physiological arousal measures. Specifically, light-to-moderate drinkers had positive associations between methylation and stimulation and tension (r's = 0.21-0.24), and heavy drinkers had negative associations (r's = -0.15 to -0.21). There were also significant interaction effects on changes in tension (β = 0.31, P < 0.01), systolic blood pressure (β = 0.74, P < 0.01) and marginal effects on stimulation (β = 0.15, P = 0.07) during the infusion, such that methylation was associated with decreased arousal among light-to-moderate drinkers (r's = -0.12 to -0.25) but stable or increased arousal among heavy drinkers (r's = 0.05-0.19).

Conclusions

Findings suggest that the relationship between TLR4 methylation and subjective and physiological arousal during acute alcohol intoxication depends upon on self-reported alcohol use. These data demonstrate the influence of TLR4 on subjective responses to alcohol, thereby supporting the need for further research on its potential as a pharmacological treatment target.

Differences in the subjective and motivational properties of alcohol across alcohol use severity: application of a novel translational human laboratory paradigm

The Allostatic Model proposes that Alcohol Use Disorder (AUD) is associated with a transition in the motivational structure of alcohol drinking: from positive reinforcement in early-stage drinking to negative reinforcement in late-stage dependence. However, direct empirical support for this preclinical model from human experiments is limited. This study tests predictions derived from the Allostatic Model in humans. Specifically, this study tested whether alcohol use severity (1) independently predicts subjective responses to alcohol (SR; comprised of stimulation/hedonia, negative affect, sedation and craving domains), and alcohol self-administration and 2) moderates associations between domains of SR and alcohol self-administration. Heavy drinking participants ranging in severity of alcohol use and problems (N = 67) completed an intravenous alcohol administration paradigm combining an alcohol challenge (target BrAC = 60 mg%), with progressive ratio self-administration. Alcohol use severity was associated with greater baseline negative affect, sedation, and craving but did not predict changes in any SR domain during the alcohol challenge. Alcohol use severity also predicted greater self-administration. Craving during the alcohol challenge strongly predicted self-administration and sedation predicted lower self-administration. Neither stimulation, nor negative affect predicted self-administration. This study represents a novel approach to translating preclinical neuroscientific theories to the human laboratory. As expected, craving predicted self-administration and sedation was protective. Contrary to the predictions of the Allostatic Model, however, these results were inconsistent with a transition from positively to negatively reinforced alcohol consumption in severe AUD. Future studies that assess negative reinforcement in the context of an acute stressor are warranted.

Relationships of Impulsivity and Subjective Response to Alcohol Use and Related Problems

OBJECTIVE

Impulsivity and subjective response to alcohol are predictors of alcohol use disorder. The purpose of this study was to replicate and extend prior research examining relationships between impulsivity and subjective response patterns. In addition, impulsivity and initial subjective response patterns were examined in relation to current heavy episodic drinking and alcohol-related problems.

METHOD

Data were cross-sectional, retrospective self-reports, obtained from baseline assessments from five studies affiliated with the Yale Center for the Translational Neuroscience of Alcoholism. Analyses were conducted in a sample restricted to nondependent, young adults (n = 186) and in a larger, more heterogeneous sample (n = 363). Data were analyzed using hierarchical regression in three separate types of models.

RESULTS

In the young adult, nondependent sample, impulsivity was a statistically significant predictor of lower recent sedative subjective response. Impulsivity and initial sedative subjective response patterns were statistically significant predictors of past-year heavy drinking. Impulsivity, but not initial subjective response patterns, was a statistically significant predictor of past-year alcohol-related problems. Findings in the larger sample were similar.

CONCLUSIONS

More-impulsive individuals may perceive less sedation from alcohol, which is associated with increased heavy drinking. However, higher levels of impulsivity may be more responsible than diminished subjective response for poor decision making that results in negative drinking consequences. These results suggest that high impulsivity and certain subjective response patterns are worthy intervention targets.

Pharmacogenetic Effects of Naltrexone in Individuals of East Asian Descent: Human Laboratory Findings from a Randomized Trial

BACKGROUND

Genetic variation in the endogenous opioid system has been identified as 1 potential source of individual variability in naltrexone treatment outcomes. The majority of naltrexone pharmacogenetic studies have focused on a particular single nucleotide polymorphism (SNP) of the mu-opioid receptor gene (OPRM1; rs1799971; commonly known as the Asn40Asp SNP) in Caucasian samples with decidedly mixed results. The goal of this study was to test the pharmacogenetic effects of naltrexone on subjective response to alcohol and self-administration of alcohol in individuals of East Asian descent. We hypothesized that naltrexone, compared with placebo, would potentiate the aversive and sedative effects of alcohol and reduce alcohol self-administration to a greater extent in Asp40 carriers.

METHODS

Participants (N = 77; Asn40Asn, n = 29; Asn40Asp, n = 34, and Asp40Asp, n = 14) completed 2 double-blinded and counterbalanced experimental sessions: one after taking naltrexone (50 mg/d) for 5 days and one after taking matched placebo for 5 days. In each experimental session, participants received a priming dose of intravenous alcohol up to the breath alcohol concentration target of 0.06 g/dl which was immediately followed by an alcohol self-administration period (1 hour).

RESULTS

There were no pharmacogenetic effects observed for alcohol-induced stimulation, sedation, craving for alcohol, or alcohol self-administration in the laboratory. During the self-administration period, Asp40 carriers consumed fewer drinks and had a longer latency to first drink as compared to Asn40 homozygotes.

CONCLUSIONS

These findings in East Asians add to the mixed literature on naltrexone pharmacogenetics from predominantly Caucasian samples and highlight the complexity of these effects and their overall limited replicability. It is plausible that a consistent pharmacogenetic effect in tightly controlled preclinical and experimental medicine models "fades" in more complex and heterogeneous settings and samples.

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.

The Neurobiological Mechanism of Chemical Aversion (Emetic) Therapy for Alcohol Use Disorder: An fMRI Study

A recent NIH epidemiology study found the lifetime prevalence of alcohol use disorder in the United States to be 29%. Alcohol drinking behavior is strongly "learned" via pleasure center activation/reinforcement. Alcohol craving is a powerful desire to drink alcoholic beverages. Craving was added as one of the defining criteria for alcohol use disorder in DSM5, and craving reduction is becoming an increasingly important treatment goal. In the current study, patients with alcohol use disorder received 10 days of inpatient multi-modal treatments at Schick Shadel Hospital (SSH) of Seattle. The treatments included five chemical aversion conditioning sessions that associated alcohol cues (and alcohol) with nausea and emesis. All patients met DSM4 criteria for alcohol use disorder, were heavy drinkers, and reported craving alcohol pre-treatment. Craving reduction was one of the primary treatment goals. This is the first fMRI study to measure the effects of chemical aversion therapy on alcohol craving-related brain activity. Patients were recruited as subjects for the University of Washington (UW) brain scan study following SSH admission but before treatment onset. Prior to treatment, patients reported craving/desire for alcohol. After treatment (after four SSH chemical aversion treatments, again after five SSH chemical treatments, 30 and 90-days post-discharge), these same patients reported avoidance/aversion to alcohol. Most of the participants (69%) reported being still sober 12 months post-treatment. Consistent with a craving reduction mechanism of how chemical aversion therapy facilitates sobriety, results of the UW fMRI brain scans showed significant pre- to post-treatment reductions in craving-related brain activity in the occipital cortex. Additional fMRI brain scan studies are needed to further explore the neurobiological mechanism of chemical aversion therapy treatment for alcohol use disorder, and other substance use disorders for which chemical aversion therapy is used (e.g., opioid dependence and cocaine dependence). Substance use disorders are estimated to affect well over one billion people worldwide.

Association of Anticipated and Laboratory-Derived Alcohol Stimulation, Sedation, and Reward

BACKGROUND

Laboratory alcohol challenges are the "gold standard" for obtaining accurate measurements of subjective alcohol stimulation, sedation, and reward. However, these approaches are time and resource intensive. This study examined the extent to which self-reported anticipated alcohol stimulation, sedation, and reward corresponded with those same responses measured with the Biphasic Alcohol Effects Scale (BAES), Brief-BAES (B-BAES), and Drug Effects Questionnaire (DEQ) during a controlled laboratory alcohol challenge.

METHODS

Participants were 106 light-to-heavy social drinkers (58.5% male; mean ± SD age = 35.8 ± 3.2 years) who completed the Anticipated BAES and DEQ, as well as laboratory-derived versions of these scales 30 and 60 minutes after consuming placebo and 0.8 g/kg alcohol on separate days as part of laboratory sessions in the Chicago Social Drinking Project.

RESULTS

Anticipated BAES/B-BAES and Anticipated DEQ alcohol effects were strong predictors of their corresponding laboratory-derived responses during both the rising limb and at peak breath alcohol concentrations. Effects were significant even when accounting for age, sex, past-month heavy drinking frequency, and laboratory session order (placebo or alcohol first).

CONCLUSIONS

This study provides strong preliminary support for measuring anticipated alcohol effects with the Anticipated BAES/B-BAES and Anticipated DEQ as a proxy of subjective responses experienced during a controlled laboratory alcohol challenge. The findings lend support for these measures as viable alternatives to other anticipatory scales when laboratory-derived alcohol response measurement is not feasible.

A cis-eQTL in OPRM1 is Associated with Subjective Response to Alcohol and Alcohol Use

BACKGROUND

A functional polymorphism within the μ-opioid receptor (OPRM1) gene, rs1799971 (A118G), previously has been associated with measures of alcohol use and sensitivity to its effects, but findings have been inconclusive. A recent study suggested that a second nearby variant within OPRM1, rs3778150, is robustly associated with heroin dependence and fully explained a smaller observed association with rs1799971. Given evidence that the rs3778150-C allele is associated with decreased OPRM1 expression levels in the human brain, the current study sought to test the hypothesis that rs3778150 represents a causal variant within OPRM1 that increases risk for a variety of alcohol use phenotypes.

METHODS

Participants with genotype and phenotype data from a larger experimental study (N = 152) were assessed on measures of subjective response to alcohol and alcohol use. Measures included (i) the Self-Rating of the Effects of Alcohol and the Alcohol Sensitivity Questionnaire, (ii) the Biphasic Alcohol Effects Scale (BAES) and ratings of subjective intoxication, and (iii) average number of drinks per week in the past month.

RESULTS

Compared to rs3778150-T homozygous individuals, carriers of the rs3778150-C allele exhibited significantly lower retrospective self-report levels of alcohol sensitivity. Carriers of the rs3778150-C allele also exhibited lower levels of BAES alcohol-related stimulation during an alcohol challenge and reported higher levels of drinking in the last 30 days. With the exception of lower levels of BAES alcohol-related sedation, the rs1799971 variant did not show consistent significant association with any of the alcohol phenotypes in the presence of rs3778150.

CONCLUSIONS

Results suggest that rs3778150 may be causally related to alcohol use phenotypes, and could potentially account for previously observed associations of rs1799971 with substance use phenotypes. Future studies may investigate potential causal relations among genetic variants in OPRM1, subjective response to alcohol, and drinking phenotypes to further delineate the effects of rs3778150.

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.

Test-retest reliability of the underlying latent factor structure of alcohol subjective response

RATIONALE

Alcohol subjective experiences are multi-dimensional and demonstrate wide inter-individual variability. Recent efforts have sought to establish a clearer understanding of subjective alcohol responses by identifying core constructs derived from multiple measurement instruments.

OBJECTIVE

The aim of this study was to evaluate the temporal stability of this approach to conceptualizing alcohol subjective experiences across successive alcohol administrations in the same individuals.

METHODS

Healthy moderate alcohol drinkers (n = 104) completed six experimental sessions each, three with alcohol (0.8 g/kg), and three with a non-alcoholic control beverage. Participants reported subjective mood and drug effects using standardized questionnaires before and at repeated times after beverage consumption. We explored the underlying latent structure of subjective responses for all alcohol administrations using exploratory factor analysis and then tested measurement invariance over the three successive administrations using multi-group confirmatory factor analyses.

RESULTS

Exploratory factor analyses on responses to alcohol across all administrations yielded four factors representing "Positive mood," "Sedation," "Stimulation/Euphoria," and "Drug effects and Urges." A confirmatory factor analysis on the separate administrations indicated acceptable configural and metric invariance and moderate scalar invariance.

CONCLUSIONS

In this study, we demonstrate temporal stability of the underlying constructs of subjective alcohol responses derived from factor analysis. These findings strengthen the utility of this approach to conceptualizing subjective alcohol responses especially for use in prospective and longitudinal alcohol challenge studies relating subjective response to alcohol use disorder risk.

Alcohol-induced place conditioning in moderate social drinkers

AIMS

To test whether non-dependent drinkers show place preference for a location paired with alcohol, and to test if the amount of time spent in the alcohol-paired location is related to self-reported subjective alcohol effects experienced in that environment.

DESIGN

Two groups of subjects completed six conditioning sessions: three with alcohol (0.8 g/kg) and three without alcohol. Individuals were assigned randomly to two groups, paired and unpaired, in a 2 : 1 ratio. The paired group (n = 78) received alcohol in one testing room and no-alcohol in another testing room (biased assignment). The unpaired group (n = 30) received alcohol and no-alcohol in each testing room.

SETTING

Human Behavioral Pharmacology Laboratory, University of Chicago, Chicago, IL, USA (single site).

PARTICIPANTS

Healthy male and female social drinkers (n = 108) aged 21-40 years participated in the study (consisting of 10 separate laboratory visits) between March 2012 and August 2014 (an average of 36 separate subject visits per month).

MEASUREMENTS

The primary outcome measure was the pre- to post-conditioning change in the percentage of time spent in the least preferred room (obtained during drug-free exploration tests conducted at separate visits before and after the six conditioning sessions were completed). Secondary measures included self-reported subjective mood and drug effects obtained during the conditioning sessions.

FINDINGS

The groups differed in the change in the percentage of time spent in the initially least preferred room, from pre- to post-conditioning; paired group = 11.0%, unpaired group = -1.4%, mean difference = 12.4%, 95% confidence interval = 1.9-23.0, P = 0.02. The change in the percentage of time spent in the least-preferred room was related to the self-reported sedative effects of alcohol during conditioning sessions among paired group participants only.

CONCLUSIONS

Non-dependent consumers of alcohol appear to develop a behavioral preference for locations paired with alcohol consumption, more so for those who experience sedative effects from alcohol in those locations.

Experimental psychopathology paradigms for alcohol use disorders: Applications for translational research

In spite of high prevalence and disease burden, scientific consensus on the etiology and treatment of Alcohol Use Disorder (AUD) has yet to be reached. The development and utilization of experimental psychopathology paradigms in the human laboratory represents a cornerstone of AUD research. In this review, we describe and critically evaluate the major experimental psychopathology paradigms developed for AUD, with an emphasis on their implications, strengths, weaknesses, and methodological considerations. Specifically we review alcohol administration, self-administration, cue-reactivity, and stress-reactivity paradigms. We also provide an introduction to the application of experimental psychopathology methods to translational research including genetics, neuroimaging, pharmacological and behavioral treatment development, and translational science. Through refining and manipulating key phenotypes of interest, these experimental paradigms have the potential to elucidate AUD etiological factors, improve the efficiency of treatment developments, and refine treatment targets thus advancing precision medicine.

Subjective Response to Alcohol as a Research Domain Criterion

BACKGROUND

Individual differences in the subjective experience of the pharmacological effects of alcohol have long been implicated in the likelihood that one will drink heavily and develop alcoholism. The theme of this conceptual review and perspective article is to synthesize the literature on subjective responses to alcohol and to set an agenda for the next generation of research in the area. Specifically, we contend that in order for subjective response to alcohol to play a prominent role in alcoholism research, it is critical that it be studied as a multimodal phenotype.

METHODS

First, we review the human research on subjective response to alcohol measured under controlled laboratory conditions and draw recommendations for the application of these findings to understanding alcoholism neurobiology in humans. Second, we highlight multimodal approaches, including studies of the genetic and neural substrates of individual differences in subjective response to alcohol. Third, we review treatment implications with a focus on subjective response to alcohol as an intervention target. Upon review of the research on subjective response to alcohol across levels of analyses, we provide recommendations for leveraging these phenotypes in a systematic and methodologically rigorous fashion that can address central questions about alcoholism etiology, disease progression, and personalized treatment.

DISCUSSION

The approach recommended herein is largely consistent with the Research Domain Criteria (RDoC) initiative across the National Institute of Mental Health. The defining feature of such domains is that they inform behavior yet be amenable to examination through multiple units of analysis, such as molecular, genetic, circuit-level, and behavioral measurements. To that end, we contend that subjective response to alcohol represents a behaviorally and biologically plausible phenotype upon which to build using the RDoC framework for understanding alcohol use disorder.

Genome characterization of the selected long- and short-sleep mouse lines

The Inbred Long- and Short-Sleep (ILS, ISS) mouse lines were selected for differences in acute ethanol sensitivity using the loss of righting response (LORR) as the selection trait. The lines show an over tenfold difference in LORR and, along with a recombinant inbred panel derived from them (the LXS), have been widely used to dissect the genetic underpinnings of acute ethanol sensitivity. Here we have sequenced the genomes of the ILS and ISS to investigate the DNA variants that contribute to their sensitivity difference. We identified ~2.7 million high-confidence SNPs and small indels and ~7000 structural variants between the lines; variants were found to occur in 6382 annotated genes. Using a hidden Markov model, we were able to reconstruct the genome-wide ancestry patterns of the eight inbred progenitor strains from which the ILS and ISS were derived, and found that quantitative trait loci that have been mapped for LORR were slightly enriched for DNA variants. Finally, by mapping and quantifying RNA-seq reads from the ILS and ISS to their strain-specific genomes rather than to the reference genome, we found a substantial improvement in a differential expression analysis between the lines. This work will help in identifying and characterizing the DNA sequence variants that contribute to the difference in ethanol sensitivity between the ILS and ISS and will also aid in accurate quantification of RNA-seq data generated from the LXS RIs.

Individual differences in subjective alcohol responses and alcohol-related disinhibition

There are important individual differences in acute subjective responses to alcohol, which have often been assessed using self-report measures. There is also evidence of meaningful between-persons variation in alcohol's disinhibiting effects on behavior, such that some individuals become more impaired on tasks of inhibition than do others after an intoxicating dose. The degree to which subjective alcohol responses correspond with these disinhibition effects is not yet clear. In this study, we tested associations among indices of subjective alcohol responses and their correspondence with sensitivity to alcohol-related disinhibition. We recruited recent-binge-drinking emerging adults (N = 82) for a group-administered, placebo-controlled, within-subject, counterbalanced alcohol challenge in a simulated bar laboratory. Confirmatory factor analyses revealed that a 2-factor model with several cross-loadings explained associations among the subjective measures well, replicating a differentiation between stimulant-like and sedative-like subjective responses. Controlling sex and placebo performance, participants who reported greater subjective stimulant-like effects-but not sedative-like effects-experienced more alcohol-related disinhibition, as measured by cued go/no-go task inhibitory failures. This association was small-to-moderate in magnitude. The results of this study highlight the distinction between stimulant-like and sedative-like subjective alcohol effects. They suggest, additionally, that there may be modest commonalities between alcohol's acute impacts on subjective stimulation and objective disinhibition.

Current insights into the mechanisms and development of treatments for heavy drinking cigarette smokers

There is a strong association between cigarette smoking and alcohol use at the epidemiological, behavioral, and molecular levels, and this co-use creates substantial impediments to smoking cessation among smokers who are also heavy drinkers. Compared with individuals who only smoke, those who both drink and smoke heavily experience more severe health consequences and have greater difficulty in quitting smoking. During smoking abstinence, greater alcohol use is associated with decreased odds of smoking cessation, and smokers are substantially more likely to experience a smoking lapse during drinking episodes. As heavy drinking smokers are less responsive to the currently available pharmacological treatments, this subgroup of high-risk substance users possesses a unique clinical profile and treatment needs. Thus, treatment development for heavy drinking smokers represents a significant and understudied research area within the field of smoking cessation. This review will briefly describe findings from epidemiological, behavioral, and molecular studies illustrating alcohol and tobacco co-use and identify how the behavioral and neurobiological mechanisms underlying the interaction of alcohol and nicotine may inform the development of targeted treatments for this unique population of smokers.