Gender specific effects of a mild stressor on alcohol cue reactivity in heavy social drinkers

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.

Negative affect among daily smokers: A systematic review and meta-analysis

BACKGROUND

Negative Affect (NA), as a personality trait is a tendency towards experiencing a more negative emotion. The body of research suggests that NA encourages smoking relapse and smoking as a reason for NA reduction, though. The likelihood of this connection does not seem to be bright yet. The present study critically reviews researches to synthesize the existing literature to determine the strength of this linkage.

METHODS

Key-word related research was systematically searched in PubMed, PsychINFO, Science Direct and Google Scholar for studies conducted from 1980 to 2019, followed by, the assessment and selection of retrieved studies based on defined inclusion criteria. A random-effects meta-analysis model was used to examine the prospective relationship between NA and smoking. Meta-regression was also used to dig for possible explanations of heterogeneity. Furthermore a multi-moderators model and sub-group analyses examined the moderating factors.

RESULTS

Forty effect-sizes comprising 12 cross-sectional studies, 28 longitudinal studies and 24,913 participants were included in the meta-analysis. The forest plot of the pooled correlation effect size in the random model indicates a significant effect size of the relationship between NA and smoking (r = 0.11; 95%CI 0.071-0.15, P = 0.001) in the meta-analysis with high heterogeneity (Q = 473.916; df=39; P = 0.001; I²=91.77%). Also, the pooled effect size was obtained as 0.143 (95%CI 0.071-0.214) for light-to-moderate and 0.112 (95%CI 0.057-0.166) for moderate-to-heavy smokers, with the effect size ranging from 0.061 to 0.195 which was significant among all subtypes, though this trend seem higher among adolescents, males, and longitudinal studies than in adults, females, and cross-sectional studies.

LIMITATIONS

The review was limited to English articles, and the heterogeneity of the studies were high.

CONCLUSION

These results support the notion that NA was positively and weakly linked to smoking and this linkage is stronger in light-to-moderate smokers, males, and adolescents. Theoretical and clinical implications are discussed with the aim of extending future directions on NA and smoking.

The Role of Stress, Trauma, and Negative Affect in Alcohol Misuse and Alcohol Use Disorder in Women

Recent evidence indicates that the United States is facing a public health crisis of alcohol misuse and alcohol use disorder (AUD), which has been fueled in part by dramatic rises in binge and heavy drinking and prevalence of AUD in women. Historically, alcohol misuse and AUD have been more prevalent in men than in women. However, recent evidence on data from the past decade shows increases in AUD prevalence rates that are associated with substantially higher binge and heavy drinking and AUD prevalence in women compared to men. This paper first addresses the key roles of stress, trauma, childhood maltreatment, negative affect, and mood and anxiety disorders; sex differences in the presentation of these psychosocial and psychological factors; and their contributions to alcohol misuse, escalation to binge and heavy drinking, and transition to AUD in women. Also examined are potential central and peripheral biological mechanisms by which stressors and traumatic experiences, as well as chronic stress states-including depression and anxiety-may facilitate differential pathways to alcohol misuse, escalation, and transition to AUD in women. Finally, this paper discusses major gaps in the literature on sex differences in these areas as well as the need for greater research on sex-specific pathways to alcohol misuse and transition to AUD, so as to support a more comprehensive understanding of AUD etiology and for the development of new strategies for prevention and treatment of alcohol misuse and AUD in women.

Alcohol consumption alters Gdnf promoter methylation and expression in rats

Alcohol use disorder is one of the most disabling diseases worldwide. Glial-cell derived neurotrophic factor (Gdnf) shows promising results concerning the inhibition of alcohol consumption in rodent models. We investigated the epigenetic regulation of Gdnf following ethanol consumption and withdrawal in a rat model. 32 Wistar rats underwent 7 weeks of intermittent access to alcohol in a 2-bottle choice (IA2BC). Whole blood, Nucleus Accumbens (NAc) and Ventral Tegmental Area (VTA) were collected immediately after the last 24 h of an alcohol-drinking session (alcohol group, AG) or 24 h after withdrawal (withdrawal group, WG). MRNA levels were measured using real-time quantitative PCR. Bisulfite-conversion of DNA and capillary sequencing was used to determine methylation levels of the core promoter (CP) and the negative regulatory element (NRE). The CP of the AG in the NAc was significantly less methylated compared to controls (p < 0.05). In the NAc, mRNA expression was significantly higher in the WG (p < 0.05). In the WG, mRNA expression levels in the VTA were significantly lower (p < 0.05) and showed significantly less methylation in the NRE in the VTA (p < 0.001) and the NAc (p < 0.01) compared to controls. Changes in the cerebral mRNA expression correspond to alterations in DNA methylation of the Gdnf promoter in a rodent model. Our results hold clinical relevance since differences in Gdnf mRNA expression and DNA methylation could be a target for pharmacological interventions.

Metabotropic Glutamate Receptor Subtype 5 in Alcohol-Induced Negative Affect

Allosteric modulators of metabotropic glutamate 5 receptors (mGlu5 receptors) have been identified as a promising treatment to independently alleviate both negative affective states and ethanol-seeking and intake. However, these conditions are often comorbid and might precipitate one another. Acute and protracted ethanol withdrawal can lead to negative affective states. In turn, these states are primary drivers of alcohol relapse, particularly among women. The current review synthesizes preclinical studies that have observed the role of mGlu5 receptor modulation in negative affective states following ethanol exposure. The primary behavioral assays discussed are ethanol-seeking and intake, development and extinction of ethanol-associated cues and contexts, behavioral despair, and anxiety-like activity. The work done to-date supports mGlu5 receptor modulation as a promising target for mediating negative affective states to reduce ethanol intake or prevent relapse. Limitations in interpreting these data include the lack of models that use alcohol-dependent animals, limited use of adolescent and female subjects, and a lack of comprehensive evaluations of negative affective-like behavior.

Risk profiles for heavy drinking in adolescence: differential effects of gender

Abnormalities across different domains of neuropsychological functioning may constitute a risk factor for heavy drinking during adolescence and for developing alcohol use disorders later in life. However, the exact nature of such multi-domain risk profiles is unclear, and it is further unclear whether these risk profiles differ between genders. We combined longitudinal and cross-sectional analyses on the large IMAGEN sample (N ≈ 1000) to predict heavy drinking at age 19 from gray matter volume as well as from psychosocial data at age 14 and 19-for males and females separately. Heavy drinking was associated with reduced gray matter volume in 19-year-olds' bilateral ACC, MPFC, thalamus, middle, medial and superior OFC as well as left amygdala and anterior insula and right inferior OFC. Notably, this lower gray matter volume associated with heavy drinking was stronger in females than in males. In both genders, we observed that impulsivity and facets of novelty seeking at the age of 14 and 19, as well as hopelessness at the age of 14, are risk factors for heavy drinking at the age of 19. Stressful life events with internal (but not external) locus of control were associated with heavy drinking only at age 19. Personality and stress assessment in adolescents may help to better target counseling and prevention programs. This might reduce heavy drinking in adolescents and hence reduce the risk of early brain atrophy, especially in females. In turn, this could additionally reduce the risk of developing alcohol use disorders later in adulthood.

Real-time social stress response and subsequent alcohol use initiation among female adolescents

Adolescents who are particularly sensitive to social stress may be vulnerable to earlier alcohol consumption and related problems. Although a small literature supports this contention, previous studies mostly relied on retrospective self-report. The current study used discrete-time survival analysis (DTSA) to test whether real-time social stress responding (via laboratory induction) and social anxiety symptoms predicted 12-month alcohol onset in an alcohol-naïve sample of young female adolescents. Anxiety elicited by the task was expected to predict greater and earlier rates of alcohol incidence, particularly among girls with higher levels of self-reported social anxiety symptoms. Participants were 104 community-recruited girls (ages 12-15 years) who completed a modified Trier Social Stress Test and questionnaires; follow-up calls were conducted at 3, 6, 9, and 12 months after the laboratory visit. Self-reported anxiety was assessed in response to the stressor following acclimation (baseline), instruction (anticipation), and speech (posttask). By 12 months, 30.8% of the sample had consumed a full alcoholic beverage. The DTSA revealed that girls with higher levels of social anxiety and greater elevations in anticipatory (but not posttask) anxiety compared to baseline had earlier alcohol initiation. This is the first study to examine the role of both laboratory-induced anxious responding and retrospective reports of social anxiety as prospective predictors of alcohol incidence. These preliminary findings suggest that adolescent girls who are more sensitive to social stress may be at risk for experimenting with alcohol earlier than their peers. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Striatal alcohol cue-reactivity is stronger in male than female problem drinkers

Despite apparent sex differences in the development and treatment of alcohol use disorder, relatively little is known about the underlying neural mechanisms. In this study, we therefore investigated neural cue-reactivity in a sample of male (n = 28) and female (n = 27) problem drinkers (matched on age and alcohol use severity) with an average alcohol use disorder identification test score of 12 which is indicative of a likely alcohol use disorder. Neural cue-reactivity data were extracted from four regions of interest: the ventral and dorsal striatum and the ventral and dorsal anterior cingulate cortex, with a significance level set at p < 0.05. While the cue-reactivity paradigm induced similar levels of self-reported craving in men and women, visual alcohol cues induced significantly stronger striatal activation in men compared to drinkers. While sex differences in ventral striatal cue-reactivity were partly explained by sex differences in alcohol intake, cannabis use, negative affect and anxiety, this was not the case for sex differences in dorsal striatal cue-reactivity. These results suggest that alcohol cues are differentially processed by men and women and that the neurobiological mechanisms behind cue-reactivity differ between the sexes. Consequently, paradigms using alcohol-related pictures may not be optimal to induce cue-reactivity in female drinkers and may not be optimal to measure neurobiological markers of alcohol use severity and relapse. Future alcohol cue-reactivity studies should, in addition to including both men and women, include different types of cues (e.g., stressors and imagery in addition to pictures) to assess sex differences in alcohol cue-reactivity.

Excluded, then inebriated: A preliminary investigation into the role of ostracism on alcohol consumption

Introduction

Ostracism has only recently been investigated as a relevant social stressor that might precede college student alcohol use. The present study continues initial efforts to examine the effects of ostracism on subsequent alcohol consumption in the laboratory. A 2 (sex: male, female) × 2 (condition: ostracism, control) between-subjects experimental design was conducted to examine the effects of these variables on alcohol consumption in the laboratory.

Methods

Social drinking college students (N = 40; 43% female) were randomly assigned to one of two social interaction tasks: either an in-person conversation from which the participant was excluded by two confederates, or independently rating neutrally valenced photographs alongside confederates. Participants then consumed a priming drink (targeted dose = 0.03 BrAC) before completing a mock taste test of up to 710 ml of light beer. Amount consumed (in ml) during the mock taste test served as the primary dependent variable.

Results

The ostracism condition was effective at decreasing mood and psychological need variables (i.e., control, belonging) compared to the control condition. After removing from analyses those who identified the confederates as part of the study (n = 7; 3 control, 4 ostracism), results indicated that males consumed more beer than females, and that ostracized participants trended toward consuming more beer than control participants.

Conclusions

Findings contribute important methodological additions to a burgeoning literature on the effects of ostracism on drinking, and suggest that ostracism may be a valuable addition to studies examining drinking to cope behaviors.

Sex differences in daily life stress and craving in opioid-dependent patients

BACKGROUND

Responses to stress and drug craving differ between men and women. Differences in the momentary experience of stress in relation to craving are less well-understood.

OBJECTIVES

Using ecological momentary assessment (EMA), we examined sex differences in real-time in two areas: (1) causes and contexts associated with stress, and (2) the extent to which stress and drug cues are associated with craving.

METHODS

Outpatients on opioid-agonist treatment (135 males, 47 females) reported stress, craving, and behavior on smartphones for 16 weeks. They initiated an entry each time they felt more stressed than usual (stress event) and made randomly prompted entries 3 times/day. In stress-event entries, they identified the causes and context (location, activity, companions), and rated stress and craving severity.

RESULTS

The causes reported for stress events did not differ significantly by sex. Women reported arguing and being in a store more often during stress events, and men reported working more often during stress events, compared to base rates (assessed via random prompts). Women showed a greater increase in opioid craving as a function of stress (p < 0.0001) and had higher stress ratings in the presence of both stress and drug cues relative to men (p < 0.01). Similar effects were found for cocaine craving in men (p < 0.0001).

CONCLUSION

EMA methods provide evidence based on real-time activities and moods that opioid-dependent men and women experience similar contexts and causes for stress but differ in stress- and cue-induced craving. These findings support sex-based tailoring of treatment, but because not all participants conformed to the overall pattern of sex differences, any such tailoring should also consider person-level differences.

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.

Sex differences in reinstatement of alcohol seeking in response to cues and yohimbine in rats with and without a history of adolescent corticosterone exposure

RATIONALE

Women represent a vulnerable and growing population with respect to alcohol abuse. Elevated glucocorticoid exposure in adolescence increases addiction risk and stress sensitivity in adulthood. However, little is known about sex differences in ethanol craving-like behavior.

OBJECTIVE

This study characterized sex differences in ethanol-motivated behavior following ethanol-paired cues and/or acute stimulation of the HPA axis in male and female rats with or without exposure to chronically elevated glucocorticoids in adolescence.

METHODS

Adolescent corticosterone-treated (Experiment 1) or naïve (Experiment 2) male and female rats were trained as adults to self-administer ethanol paired with a cue, and tested for the effects of this cue, alone or in combination with yohimbine, on the reinstatement of ethanol seeking.

RESULTS

Females showed elevated ethanol self-administration and seeking compared to males. In Experiment 1, corticosterone exposure in adolescence augmented cue-induced reinstatement of ethanol seeking in females only, and females were more sensitive to yohimbine in promoting reinstatement. Experiment 2 replicated these findings and showed that exposure to both yohimbine and alcohol-related cues enhanced the reinstatement of alcohol seeking, producing additive effects in females. Corticosterone levels were higher in females and in yohimbine-treated rats, and corticosterone and estradiol correlated with responding during reinstatement.

CONCLUSIONS

Chronic manipulations in adolescence and acute manipulations in adulthood of the HPA axis increase cue-induced reinstatement of ethanol seeking to a greater degree in females than in males. Elucidating the mechanisms that underlie these effects may lead to the development of sex-specific interventions aimed at mitigating alcohol relapse risk in females.

Perceived racial discrimination and negative-mood-related drinking among African American college students

OBJECTIVE

Research consistently shows a positive association between racial discrimination and problematic alcohol use among African Americans, but little is known about the micro-processes linking this pernicious form of stress to drinking. One possibility is that the cumulative effects of discrimination increase individuals' likelihood of negative-mood-related drinking. In the current study, we examined whether individual differences in lifetime perceived racial discrimination among African American college students moderate relations between daily negative moods and evening alcohol consumption in both social and nonsocial contexts.

METHOD

Data came from an online daily diary study of 441 African Americans (58% female) enrolled at a historically black college/university. Lifetime discrimination was measured at baseline. For 30 days, students reported the number of drinks they consumed the night before both socially and nonsocially, as well as their daytime level of negative mood.

RESULTS

In support of the hypotheses, only men who reported higher (vs. lower) lifetime discrimination showed a positive association between daily negative mood and that evening's level of nonsocial drinking. Contrary to expectation, women who reported higher (vs. lower) discrimination showed a negative association between daily negative mood and nonsocial drinking. Neither daily negative mood nor lifetime discrimination predicted level of social drinking.

CONCLUSIONS

These findings provide further evidence that the cumulative impact of racial discrimination may produce a vulnerability to negative-mood-related drinking--but only for African American men. Importantly, these effects emerged only for nonsocial drinking, which may further explain the robust association between discrimination and problematic alcohol use.

Measures of skin conductance and heart rate in alcoholic men and women during memory performance

We examined abnormalities in physiological responses to emotional stimuli associated with long-term chronic alcoholism. Skin conductance responses (SCR) and heart rate (HR) responses were measured in 32 abstinent alcoholic (ALC) and 30 healthy nonalcoholic (NC) men and women undergoing an emotional memory task in an MRI scanner. The task required participants to remember the identity of two emotionally-valenced faces presented at the onset of each trial during functional magnetic resonance imaging (fMRI) scanning. After viewing the faces, participants saw a distractor image (an alcoholic beverage, nonalcoholic beverage, or scrambled image) followed by a single probe face. The task was to decide whether the probe face matched one of the two encoded faces. Skin conductance measurements (before and after the encoded faces, distractor, and probe) were obtained from electrodes on the index and middle fingers on the left hand. HR measurements (beats per minute before and after the encoded faces, distractor, and probe) were obtained by a pulse oximeter placed on the little finger on the left hand. We expected that, relative to NC participants, the ALC participants would show reduced SCR and HR responses to the face stimuli, and that we would identify greater reactivity to the alcoholic beverage stimuli than to the distractor stimuli unrelated to alcohol. While the beverage type did not differentiate the groups, the ALC group did have reduced skin conductance and HR responses to elements of the task, as compared to the NC group.

The relationship between perceived stress and cue sensitivity for alcohol

Previous research has shown that cue sensitivity and stress affect the risk for relapse in alcohol-dependent patients. Theoretically, a link between the two can be expected. However, a clear overview of the interplay of these factors is not yet available. The purpose of this review was to examine the empirical evidence for the influence of stress on sensitivity for alcohol-related cues. Empirical studies indexed in PubMed, EMBASE, PsycINFO, and Web of Knowledge that assessed the relation between stress and sensitivity for alcohol-related cues using subjective, behavioral and/or physiological measures were included in the review. Of the 359 articles screened, 12 were included in the review. Nine articles supported the existence of the relationship between stress and heightened cue sensitivity for alcohol-related cues, whereas three articles did not support our hypothesis. We conclude that the relationship between stress and sensitivity to alcohol cues appears to exist. In fact, there may be different factors at play: our review points toward (1) differences between the effect of psychological stress and physiological stress on cue-sensitivity, and (2) individual differences regarding coping drinking which may explain stress-induced cues sensitivity.

Effects of stress and dietary tryptophan enhancement on craving for alcohol in binge and non-binge heavy drinkers

Stress is known to play an important role in alcohol abuse, whereas binge drinking may increase individuals' susceptibility to the development of alcohol dependence. We set out to investigate whether binge drinkers (BDs) or non-BDs (NBDs) are at a greater risk of an increase in their desire for alcohol following experimental stress induction (modified Trier Social Stress Test; Experiment 1) and to explore the biological mechanisms underlying such an effect (Experiment 2). Preclinical evidence suggests that serotonin may mediate stress-induced reinstatement of alcohol intake. We therefore tested whether dietary tryptophan (TRP) enhancement would modulate stress-induced desire for alcohol and whether it would affect the two populations (BD/NBD) differently. In Experiment 1 (14 NBDs, 10 BDs; mean weekly alcohol intake 50.64 U), stress induction selectively increased strong desire for alcohol compared with the nonstressful condition in BDs. Throughout the experiment, BDs reported greater negative reinforcement type of craving than NBDs, but also a higher expectancy of alcohol-induced negative effects. In Experiment 2, 41 participants (22 NBDs, 19 BDs; mean alcohol intake 38.81 U) were given either the TRP-rich (TRP+; 9 BDs, 11 NBD) or the control (CTR; 10 BD, 11 NBD) diet before undergoing stress induction. In BDs, the TRP+ diet prevented the stress-induced increase in strong desire that was observed in individuals receiving the CTR diet. In NBDs, the TRP+ diet appeared to facilitate an increase in strong desire. These findings suggest that BDs may indeed be at a greater risk than NBDs of an increase in their craving for alcohol when stressed. Furthermore, whereas enhancement of 5-hydroxytryptamine function may moderate the impact of stress on craving in BDs, it seems to facilitate stress-induced craving in NBDs, suggesting that the serotonergic system may be differentially involved depending on individual binge drinking status.

Sex moderates stress reactivity in heavy drinkers

Psychological stress and alcohol use disorders have a well-known connection. Individual differences in stress reactivity have been an area of interest in alcohol research, particularly given the relationship between craving and stress reactivity to later relapse. The present study examines the role of sex on stress-induced alcohol craving and emotional reactivity using a guided imagery stress paradigm. Participants were 64 non-treatment seeking heavy drinkers from the community who completed a two-session protocol that included two guided imagery exposures, Stress and Neutral. Participants reported their mood and craving before and after each exposure using the Differential Emotions Scale and the Alcohol Urge Questionnaire respectively. Analyses revealed a significant Stress × Sex × Trial effect on craving [F (1,61) = 5.35; p < .05] after controlling for AUDIT scores [F (1,61) = 8.16; p < .01] such that females reported greater increases in craving from baseline to post-imagery during the stress imagery versus the neutral imagery condition, than did males. Mood reactivity analysis showed similar patterns. Specifically, there was a significant Stress × Sex × Trial effect on the anxiety subscale of the DES [F (1,61) = 15.81; p < .001] such that females reported greater increases in anxiety from baseline to post-imagery during the stress imagery versus the neutral conditions, than did males. These results suggest that female heavy drinkers were more sensitive to the effects of the stress-induction on alcohol craving and mood reactivity than males. If supported by future studies, these initial findings may help advance understanding of the mechanisms of stress and mood regulation as central to alcoholism liability and recovery in females.

Increased anxiety, voluntary alcohol consumption and ethanol-induced place preference in mice following chronic psychosocial stress

Stress exposure is known to be a risk factor for alcohol use and anxiety disorders. Comorbid chronic stress and alcohol dependence may lead to a complicated and potentially severe treatment profile. To gain an understanding of the interaction between chronic psychosocial stress and drug exposure, we studied the effects of concomitant chronic stress exposure on alcohol reward using two-bottle choice and ethanol-conditioned place preference (CPP). The study consisted of exposure of the chronic subordinate colony (CSC) mice "intruders" to an aggressive "resident" mouse for 19 consecutive days. Control mice were single housed (SHC). Ethanol consumption using two-bottle choice paradigm and ethanol CPP acquisition was assessed at the end of this time period. As expected, CSC exposure increased anxiety-like behavior and reduced weight gain as compared to SHC controls. Importantly, in the two-bottle choice procedure, CSC mice showed higher alcohol intake than SHC. When testing their response to ethanol-induced CPP, CSC mice achieved higher preference for the ethanol-paired chamber. In fact, CSC exposure increased ethanol-CPP acquisition. Taken together, these data demonstrate the long-term consequences of chronic psychosocial stress on alcohol intake in male mice, suggesting chronic stress as a risk factor for developing alcohol consumption and/or anxiety disorders.

Individual differences in elevated plus-maze exploration predicted higher ethanol consumption and preference in outbred mice

Psychiatric illnesses, such as anxiety, are highly comorbid with drug use disorders in general and alcohol abuse in particular. Unfortunately, the causal role of anxiety in ethanol addiction is still unclear. We asked the question whether high anxiety predicts predilection of mice to voluntarily consume more alcohol than water. In the current study, we used the voluntary alcohol intake in two bottle choice drinking paradigm to explore whether high anxiety predicts higher alcohol preference and intake in outbred Tuck-Ordinary "TO" mice. To this end, mice were tested for their anxiety-like behavior using the elevated plus maze, open field and the marble burying test prior to voluntary continuous access to increasing concentrations of alcohol solutions. To assess their taste discrimination, mice had access to saccharin and quinine solutions. Results showed that compared to low-anxious mice (LAM), high-anxious mice (HAM) showed greater consumption and preference for ethanol but not for saccharin and quinine suggesting alterations in the rewarding effects of alcohol. Taken together, these findings suggest a correlative link between trait anxiety and the behavioral responses to ethanol.

Yohimbine increases opioid-seeking behavior in heroin-dependent, buprenorphine-maintained individuals

RATIONALE

In laboratory animals, the biological stressor yohimbine (α(2)-noradrenergic autoreceptor antagonist) promotes drug seeking. Human laboratory studies have demonstrated that psychological stressors can increase drug craving but not that stressors alter drug seeking.

OBJECTIVES

This clinical study tested whether yohimbine increases opioid-seeking behavior.

METHODS

Ten heroin-dependent, buprenorphine-stabilized (8 mg/day) volunteers sampled two doses of hydromorphone [12 and 24 mg IM in counterbalanced order, labeled drug A (session 1) and drug B (session 2)]. During each of six later sessions (within-subject, double-blind, randomized crossover design), volunteers could respond on a 12-trial choice progressive ratio task to earn units (1 or 2 mg) of the sampled hydromorphone dose (drug A or B) vs money ($2) following different oral yohimbine pretreatment doses (0, 16.2, and 32.4 mg).

RESULTS

Behavioral economic demand intensity and peak responding (O (max)) were significantly higher for hydromorphone 2 than 1 mg. Relative to placebo, yohimbine significantly increased hydromorphone demand inelasticity, more so for hydromorphone 1-mg units (P (max) = 909, 3,647, and 3,225 for placebo, 16.2, and 32.4 mg yohimbine doses, respectively) than hydromorphone 2-mg units (P (max) = 2,656, 3,193, and 3,615, respectively). Yohimbine produced significant but clinically modest dose-dependent increases in blood pressure (systolic ≈ 15 and diastolic ≈ 10 mmHg) and opioid withdrawal symptoms, and decreased opioid agonist symptoms and elated mood.

CONCLUSIONS

These findings concur with preclinical data by demonstrating that yohimbine increases drug seeking; in this study, these effects occurred without clinically significant subjective distress or elevated craving, and partly depended on opioid unit dose.

Human laboratory paradigms in alcohol research

BACKGROUND

Human laboratory studies have a long and rich history in the field of alcoholism. Human laboratory studies have allowed for advances in alcohol research in a variety of ways, including elucidating neurobehavioral mechanisms of risk, identifying phenotypically distinct subtypes of alcohol users, investigating the candidate genes underlying experimental phenotypes for alcoholism, and testing mechanisms of action of alcoholism pharmacotherapies on clinically relevant translational phenotypes, such as persons exhibiting positive-like alcohol effects or alcohol craving. Importantly, the field of human laboratory studies in addiction has progressed rapidly over the past decade and has built upon earlier findings of alcohol's neuropharmacological effects to advancing translational research on alcoholism etiology and treatment.

METHODS AND RESULTS

To that end, the new generation of human laboratory studies has focused on applying new methodologies, further refining alcoholism phenotypes, and translating these findings to studies of alcoholism genetics, medication development, and pharmacogenetics. The combination of experimental laboratory approaches with the recent developments in neuroscience and pharmacology has been particularly fruitful in furthering our understanding of the impact of individual differences in alcoholism risk and in treatment response.

CONCLUSIONS

This review of the literature focuses on human laboratory studies of subjective intoxication, alcohol craving, anxiety, and behavioral economics. Each section discusses opportunities for phenotype refinement under laboratory conditions, as well as its application to translational science of alcoholism. A summary and recommendations for future research are also provided.

Effects of alcohol on the acquisition and expression of fear-potentiated startle in mouse lines selectively bred for high and low alcohol preference

RATIONALE

Anxiety disorders and alcohol use disorders frequently co-occur in humans perhaps because alcohol relieves anxiety. Studies in humans and rats indicate that alcohol may have greater anxiolytic effects in organisms with increased genetic propensity for high alcohol consumption.

OBJECTIVES AND METHODS

The purpose of this study was to investigate the effects of moderate doses of alcohol (0.5, 1.0, 1.5 g/kg) on the acquisition and expression of anxiety-related behavior using a fear-potentiated startle (FPS) procedure. Experiments were conducted in two replicate pairs of mouse lines selectively bred for high- (HAP1 and HAP2) and low- (LAP1 and LAP2) alcohol preference; these lines have previously shown a genetic correlation between alcohol preference and FPS (HAP > LAP; Barrenha and Chester, Alcohol Clin Exp Res 31:1081-1088, 2007). In a control experiment, the effect of diazepam (4.0 mg/kg) on the expression of FPS was tested in HAP2 and LAP2 mice.

RESULTS

The 1.5 g/kg alcohol dose moderately decreased the expression of FPS in both HAP lines but not LAP lines. Alcohol had no effect on the acquisition of FPS in any line. Diazepam reduced FPS to a similar extent in both HAP2 and LAP2 mice.

CONCLUSIONS

HAP mice may be more sensitive to the anxiolytic effects of alcohol than LAP mice when alcohol is given prior to the expression of FPS. These data collected in two pairs of HAP/LAP mouse lines suggest that the anxiolytic response to alcohol in HAP mice may be genetically correlated with their propensity toward high alcohol preference and robust FPS.

Craving in response to stress induction in a human laboratory paradigm predicts treatment outcome in alcohol-dependent individuals

RATIONALE

Alcohol dependence is associated with high rates of recidivism. Stress has been shown to increase alcohol craving in alcohol-dependent individuals, but the association between stress-induced craving and alcoholism treatment outcome is not well understood.

OBJECTIVE

The aim of the present study was to examine the relationship between strength of stress-induced alcohol craving in the human laboratory and subsequent drinking in a cohort of treatment-seeking, alcohol-dependent adults.

MATERIALS AND METHODS

This is a prospective study assessing stress-induced craving in the lab and subsequent treatment outcomes in alcohol-dependent subjects enrolled in a 12-week outpatient study. Stress was induced using a previously developed, individualized, audio recorded stress script and validated with objective (salivary cortisol) and subjective measures of distress. In vivo craving for alcohol was measured pre- and post-challenge using VAS.

RESULTS

Subjects were 28 (16 male, 12 female) alcohol-dependent outpatients. Greater stress-induced craving was associated with a blunted salivary cortisol response, significantly shorter time to alcohol relapse, higher mean drinks per week, fewer percent days abstinent, and lower rates of complete abstinence over the study duration (all p's < 0.05). Conversely, no demographic or baseline variables were significant predictors of any outcome variable.

CONCLUSIONS

These results suggest that greater stress-related increases in alcohol craving are associated with poorer alcohol treatment outcomes. The findings support the use of stress-induced craving as a predictor of alcohol relapse propensity. Furthermore, treatments that address high stress levels and the associated high levels of alcohol craving are likely to improve treatment outcomes in alcohol dependence.

Stress- and cue-elicited craving and reactivity in marijuana-dependent individuals

RATIONALE

Cue-elicited craving and stress responses have been identified as predictors of relapse in drug dependence, but little research exists on the contribution of these factors to marijuana use specifically.

OBJECTIVES

The aims of the present study were to evaluate (1) responses to a psychological stressor, (2) responses to marijuana-related cues, and (3) if an exposure to a psychological stressor augmented craving subsequently elicited by marijuana-related cue exposure in marijuana-dependent individuals.

METHODS

Subjective (craving, stress), neuroendocrine (adrenocorticotropic hormone (ACTH), cortisol), and physiologic responses to the presentation of neutral and marijuana cues were assessed after randomization to a stress (Trier Social Stress Task (TSST)) or non-stress control condition in marijuana-dependent individuals. Outcome measures were assessed at baseline, post-stressor/pre-neutral cue, post-neutral cue, and post-marijuana cue.

RESULTS

Eighty-seven participants completed procedures (stress group, n = 45; non-stress group, n = 42). The stress group had a significant increase over the non-stress group in stress rating (p < 0.001), craving (p = 0.028), cortisol (p < 0.001), and ACTH (p < 0.001) after the completion of the TSST. An increased craving response for all participants was seen following the presentation of the marijuana cues (p = 0.005). Following the TSST or non-stress condition, the non-stress group had an increase in craving to marijuana cues as compared to neutral cues (p = 0.002); an increase in craving was not observed in the stress group (p = 0.404).

CONCLUSIONS

Marijuana cue exposure and a social stressor increased craving in marijuana-dependent individuals. Completion of the TSST did not increase craving response to subsequent marijuana cue exposure.

A role for glutamate in subjective response to smoking and its action on inhibitory control

RATIONALE

Our previous study using memantine in smokers suggests that there may be a differential role for N-methyl-D-aspartate (NMDA) receptors in the subjective and cognitive effects of smoking.

OBJECTIVES

This study was designed to investigate if D-cycloserine (DCS) would modulate the subjective and cognitive effects of limited smoking.

METHODS

Forty-eight habitual smokers abstinent for a minimum of 2 h were randomly allocated to receive either placebo or 50 mg DCS (double-blind) and were subsequently required either to smoke half of one cigarette or to remain abstinent. Subjective and physiological effects of DCS were measured at baseline, 90 min postcapsule, and again after the partial-smoking manipulation, while the effects on sustained attention (rapid visual information processing test--RVIP) and cognitive flexibility (intra-extra dimensional set-shift test--IED) were evaluated only after the partial-smoking manipulation.

RESULTS

DCS alone did not produce significant subjective effects other than an increase in ratings of "Stimulated". In combination with partial smoking, however, DCS blocked the smoking-induced increase in "Stimulated" and the decrease in "Relaxed" ratings. Furthermore, in combination with smoking, DCS reduced the number of false alarms during the RVIP test (an index of inhibitory control) and produced a small increase in diastolic blood pressure. DCS failed to modulate IED performance.

CONCLUSIONS

These findings provide further evidence of a role for glutamate release in the subjective effects of smoking but not the effects on attention and cognitive flexibility. Furthermore, our results indicate that glutamate release may also be involved in the effect of smoking on inhibitory control.

Drinking and stress: an examination of sex and stressor differences using IVR-based daily data

BACKGROUND

Research on the relation of stress to alcohol consumption is inconsistent regarding the direction of effects, and this association has been shown to vary by sex and type of stress. We sought to build upon the stress-drinking literature by examining the direction of the stress-drinking association over time as well as sex and stressor differences using daily data.

METHOD

246 heavy drinking adults (67% men) aged 21-82 reported daily stress levels and alcohol consumption over 180 days using Interactive Voice Response (IVR). Baseline daily hassles were examined as an alternative measure of stress. Generalized estimating equations (GEEs) were conducted to test the stress-drinking association accounting for alcohol dependency at baseline and sex and stressor type as moderators.

RESULTS

IVR daily stress predicted increased alcohol consumption the following day, whereas baseline level of daily hassles did not. Examining the opposite direction of effects, IVR ratings of daily alcohol consumption predicted decreased next-day stress. Stress predicted higher alcohol consumption the next day for men but there was no significant association for women. For both sexes, drinking predicted decreased stress the next day, but this effect was stronger for women.

CONCLUSIONS

This study generally supported the drinking to cope and self-medication hypotheses, with findings that increased stress led to increased drinking. The time-varying relation between stress and alcohol appears to be sex- and measure-specific, however. Therefore, interventions targeted at stress management found to be effective for one sex should not be presumed to be applicable to the other.

Degree of dependence influences the effect of smoking on cognitive flexibility

Pre-frontal cortical (PFC) dysfunction has been put forward as the basis for development and maintenance of addiction. To explore this relationship, the present study investigated the effects of smoking on PFC-mediated cognitive flexibility and subjective states in low- (LD) and high-dependent (HD) smokers. Twenty-four LD and 24 HD smokers (Fagerström dependence scores ≤ 4 and ≥ 5, respectively) were randomly allocated to non-smoking or smoking condition (12 LD and 12 HD participants per condition). After abstaining from smoking for a minimum of two hours volunteers completed a battery of questionnaires [nicotine-specific Visual Analogue Scales (Nic-VAS), Questionnaire of Smoking Urges (QSU) and Profile of Mood States (POMS)] at baseline [T1] and again after smoking one cigarette or remaining abstinent [T2]. Cognitive flexibility was evaluated at T2 using the Intra-Extra Dimensional Set-Shift test. The Rapid Visual Information Processing test was performed as a control nicotine-sensitive task at several time points during the experiment. Compared to LD smokers, HD smokers had higher salivary cotinine and breath CO levels at baseline and reported more craving (QSU) and felt less stimulated (Nic-VAS), vigorous, friendly and elated (POMS) throughout the experiment. Smoking increased Nic-VAS ratings of 'Buzzed' and 'Dizzy' and decreased craving in all participants. Smoking selectively impaired cognitive flexibility in HD smokers since HD smokers allocated to the smoking condition made significantly more errors with the intra-dimensional set-shift than their counterparts in the abstinent condition. No effect of smoking on RVIP test was observed, most likely due to the practice effect which was significant in both groups of smokers. The practice effect, however, was more pronounced in LD smokers. This study demonstrates that PFC-mediated cognitive effects of smoking as well as subjective reports vary according to the degree of nicotine dependence.

Smoking cue reactivity across massed extinction trials: negative affect and gender effects

Designing and implementing cue exposure procedures to treat nicotine dependence remains a challenge. This study tested the hypothesis that gender and negative affect (NA) influence changes in smoking urge over time using data from a pilot project testing the feasibility of massed extinction procedures. Forty-three smokers and ex-smokers completed the behavioral laboratory procedures. All participants were over 17 years old, smoked at least 10 cigarettes daily over the last year (or the year prior to quitting) and had expired CO below 10 ppm at the beginning of the ~4-hour session. After informed consent, participants completed 45 min of baseline assessments, and then completed a series of 12 identical, 5-minute exposure trials with inter-trial breaks. Smoking cues included visual, tactile, and olfactory cues with a lit cigarette, in addition to smoking-related motor behaviors without smoking. After each trial, participants reported urge and negative affect (NA). Logistic growth curve models supported the hypothesis that across trials, participants would demonstrate an initial linear increase followed by a decrease in smoking urge (quadratic effect). Data supported hypothesized gender, NA, and gender×NA effects. Significant linear increases in urge were observed among high and low NA males, but not among females in either NA subgroup. A differential quadratic effect showed a significant decrease in urge for the low NA subgroup, but a non-significant decrease in urge in the high NA group. This is the first study to demonstrate gender differences and the effects of NA on the extinction process using a smoking cue exposure paradigm. Results could guide future cue reactivity research and exposure interventions for nicotine dependence.

Stress and alcohol cues exert conjoint effects on go and stop signal responding in male problem drinkers

Stress, cues, and pharmacological priming are linked with relapse to addictive behavior. Increased salience and decreased inhibitory control are thought to mediate the effects of relapse-related stimuli. However, the functional relationship between these two processes is unclear. To address this issue, a modified Stop Signal Task was employed, which used Alcohol, Neutral, and Non-Words as Go stimuli, and lexical decision as the Go response. Subjects were 38 male problem drinkers (mean Alcohol Dependence Scale (ADS) score: 18.0). Uncontrollable noise (∼ 10 min at 110 dB) was the stressor; nonalcoholic placebo beer (P-Beer) was the cue manipulation, and alcohol (0.7 g/kg), the pharmacological prime. Half the sample received alcohol, and half P-Beer. Stress and beverage (test drink vs soft drink) were manipulated within subjects on two sessions, with half the sample receiving active manipulations together and half receiving them separately. Go response time (RT) and Stop Signal RT (SSRT) were slower to Alcohol than Neutral words. Stress augmented this bias. Alcohol and P-Beer impaired overall SSRT. Stress impaired neither overall SSRT nor Go RT. SSRT to Neutral words and Non-Words correlated inversely with Go RT to Alcohol and Neutral words, and Non-Words. ADS correlated directly with SSRT to Alcohol words. A resource allocation account was proposed, whereby diversion of limited resources to salient cues effectively yoked otherwise independent Go and Stop processes. Disturbances of prefrontal norepinephrine and dopamine were cited as possibly accounting for these effects. Treatments that optimize prefrontal catecholamine transmission may deter relapse by reducing disinhibitory effects of salient eliciting stimuli.

An acute psychosocial stressor does not potentiate alcohol cue reactivity in non-treatment-seeking alcoholics

BACKGROUND

Relapse risk factors, such as psychological stress and alcohol cues, are often encountered together. Understanding how they interact has the potential to improve alcoholism treatments. This study was conducted to examine whether an acute psychosocial stressor enhanced alcohol cue reactivity in non-treatment-seeking alcoholics.

METHODS

Seventy-nine alcohol-dependent individuals (39 women) randomly received either the Trier Social Stress Test or a no-stress control condition. Stress reactivity was measured with serum adrenocorticotropic hormone and cortisol, mean arterial blood pressure, and subjective distress. Immediately following the stress manipulation, participants held and sniffed a neutral cue then their preferred alcoholic beverage. Cue reactivity was measured by 2 subjective measures of craving following each cue. Additionally, general craving was assessed with the Alcohol Urge Questionnaire at the beginning and end of the laboratory procedure.

RESULTS

The stress manipulation showed internal validity on all measures of stress reactivity. There was not a main effect of stress nor a stress × cue interaction on either cue reactivity measure. As expected, there was a main effect of cue (alcohol > neutral cue) on both measures of cue reactivity. General craving increased during the challenge, but not differently by stress group. Magnitude of stress reactivity was not associated with magnitude of cue reactivity, and all results were independent of gender.

CONCLUSION

In this well-controlled clinical laboratory study of non-treatment-seeking alcoholics, an acute psychological stressor did not make an alcohol cue a more potent urge-inducing stimulus, and stress had no effect on general alcohol craving.

The importance of glucocorticoids in alcohol dependence and neurotoxicity

Alterations in hypothalamo-pituitary adrenal (HPA) function have been described in alcoholics and in rodents after chronic alcohol consumption but the role of glucocorticoids in alcohol consumption, and the mechanisms involved, has received little attention until recently. Both alcohol consumption and withdrawal from chronic alcohol intake raise circulating glucocorticoid levels, and prolonged high concentrations of glucocorticoids are known to have detrimental effects on neuronal function and cognition. This minireview covers the ways in which glucocorticoids may be involved in drinking behavior, from social drinking to dependence, and the negative consequences of alcohol consumption seen during withdrawal which may have a detrimental effect on treatment outcome. Research shows prolonged increases in brain glucocorticoid concentrations and decreased brain glucocorticoid receptor availability (consistent with increased levels of endogenous ligand) after withdrawal from chronic alcohol treatment. Evidence suggests that increased glucocorticoid levels in the brain after chronic alcohol treatment are associated with the cognitive deficits seen during abstinence which impact on treatment efficacy and quality of life. Studies on organotypic cultures also demonstrate the importance of glucocorticoids in the neuropathological consequences of alcohol dependence.

Exploring the relationship between depressive and anxiety symptoms and neuronal response to alcohol cues

BACKGROUND

Depressive and anxiety symptoms tend to co-occur with heavy drinking. Specifically, their presence may exacerbate the severity and intractability of heavy drinking. Similarly, heavy drinking may increase the risk for and experience of depressive and anxiety symptoms. Although depressive and anxiety symptoms have been significantly correlated with alcohol craving in cue-exposure paradigms, physiological responses have not always mapped onto emotional responses. Therefore, this study sought to examine the role of depressive and anxiety symptoms using a more basic science approach, through examining functional brain changes.

METHODS

Seventy nontreatment seeking, heavy drinking adults were recruited through a college campus (n = 45 men; mean age = 22.8). They completed measures of drinking, smoking, depressive symptoms, anxiety symptoms, and a functional magnetic resonance imaging (fMRI) cue-exposure paradigm.

RESULTS

As hypothesized, depressive symptoms were positively correlated with activation during the alcohol (vs. appetitive control) cue in the insula, cingulate, ventral tegmentum, striatum, and thalamus (cluster-corrected p < 0.05, z = 2.3). Similarly, anxiety symptoms were positively correlated with activation during the alcohol (vs. appetitive control) cue in the striatum, thalamus, insula, and inferior frontal, mid-frontal, and cingulate gyri (cluster-corrected p < 0.05, z = 2.3).

CONCLUSIONS

Significant correlations were found between depressive symptoms, anxiety symptoms, and differential brain activation in response to an alcohol versus an appetitive control cue in an fMRI paradigm. Moreover, the pattern of activation mapped onto expected regions. This study strongly supports the posited relationships between depressive symptoms, anxiety symptoms, and differential brain activation in an alcohol cue-exposure paradigm with a sample of heavy drinking adults.

Gender differences in acute alcohol effects on self-regulation of arousal in response to emotional and alcohol-related picture cues

Basic mechanisms through which men and women self-regulate arousal have received little attention in human experimental addiction research, although stress-response-dampening and craving theories suggest an important role of emotional arousal in motivating alcohol use. This study examined gender differences in the effects of acute alcohol intoxication on psychophysiological and self-reported arousal in response to emotionally negative, positive, and neutral, and alcohol-related, picture cues. Thirty-six social drinkers (16 women) were randomly assigned to an alcohol, placebo, or control beverage group and exposed to picture cues every 10 s (0.1 Hz presentation frequency). Psychophysiological arousal was assessed via a 0.1-Hz heart rate variability (HRV) index. A statistically significant beverage group-by-gender interaction effect on psychophysiological, but not self-reported, arousal was found. The 0.1-Hz HRV responses to picture cues were suppressed by alcohol only in men. This gender-specific suppression pattern did not differ significantly across picture cue types. There were no significant gender differences in the placebo or control group. Greater dampening of arousal by alcohol intoxication in men, compared with women, may contribute to men's greater tendency to use alcohol to cope with stress.

Sex differences in drug-related stress-system changes: implications for treatment in substance-abusing women

Extensive research indicates that chronic substance abuse disrupts stress and reward systems of the brain. Gender variation within these stress-system alterations, including the impact of sex hormones on these changes, may influence sex-specific differences in both the development of, and recovery from, dependency. As such, gender variations in stress-system function may also provide a viable explanation for why women are markedly more vulnerable than men to the negative consequences of drug use. This article therefore initially reviews studies that have examined gender differences in emotional and biophysiological changes to the stress and reward system following the acute administration of drugs, including cocaine, alcohol, and nicotine. The article then reviews studies that have examined gender differences in response to various types of stress in both healthy and drug-abusing populations. Studies examining the impact of sex hormones on these gender-related responses are also reported. The implications of these sex-specific variations in stress and reward system function are discussed in terms of both comorbid psychopathology and treatment outcome.

Impact of Age at First Drink on Stress-Reactive Drinking

BACKGROUND

Although recent data from animal models indicate that adolescent ethanol exposure increases self-administered ethanol intake in adult rats, the impact of age at first drink on the association between stress and drinking has not been studied in humans.

METHODS

Data collected in the 2001 to 2002 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) were used to estimate the extent to which age at first drink modified the association between stress and average daily volume (ADV) of ethanol intake in a sample of 26,946 past-year drinkers. Successive models estimated the magnitude and significance of the interaction between age at first drink (ages 14 or younger, 15-17, and 18 or older) and number of stressors (out of 12 past-year negative life events) after (1) adjusting for sociodemographic characteristics, (2) additionally adjusting for family history of alcoholism, comorbid psychopathology, adolescent, and past-year tobacco and illicit drug use, and (3) additionally adjusting for all other significant interactions with number of stressors.

RESULTS

Even after adjusting for a wide range of confounders and their interactions with stress, initiation of drinking at ages 14 and younger increased the association between the number of stressors and ADV of ethanol consumption by 8% (p=0.014), when considering the full range of 12 potential stressors. In fact, the positive association between stress and consumption was significant only for this group of drinkers with early adolescent exposure to ethanol. Within this group, ADV of consumption increased by an average of 7% with each additional stressor experienced, although the exact percentage increase varied as a function of other covariates that had significant interactions with stress. When a reduced set of 4 stressors was considered, the magnitudes of the associations were mostly unchanged, but the modifying effect of age at first drink fell short of statistical significance (p=0.309) in the fully adjusted model.

CONCLUSIONS

The findings of this study are consistent with the argument that early-onset drinking may increase stress-reactive ethanol consumption; however, these findings need to be replicated in an experimental human study in order to control fully the direction of the relationship between stress and consumption.