Opioid and Dopamine Genes Interact to Predict Naltrexone Response in a Randomized Alcohol Use Disorder Clinical Trial

BACKGROUND

While the opiate antagonist, naltrexone, is approved for treating alcohol use disorder (AUD), not everyone who receives the medication benefits from it. This study evaluated whether the OPRM1 SNP rs1799971 interacts with the dopamine transporter gene DAT1/SLC6A3 VNTR rs28363170 or the catechol-O-methyltransferase (COMT) gene SNP rs4680 in predicting naltrexone response.

METHODS

Individuals who met DSM-IV alcohol dependence were randomly assigned to naltrexone (50 mg/d) or placebo based on their OPRM1 genotype (75 G-allele carriers and 77 A-allele homozygotes) and also genotyped for DAT1 VNTR (9 vs. 10 repeats) or COMT SNP (val/val vs. met carriers). Heavy drinking days (%HDD) were evaluated over 16 weeks and at the end of treatment. Effect sizes (d) for naltrexone response were calculated based on genotypes.

RESULTS

Naltrexone, relative to placebo, significantly reduced %HDD among OPRM1 G carriers who also had DAT1 10/10 (p = 0.021, d = 0.72) or COMT val/val genotypes (p = 0.05, d = 0.80), and to a lesser degree in those OPRM1 A homozygotes who were also DAT1 9-repeat carriers (p = 0.09, d = 0.70) or COMT met carriers (p = 0.03, d = 0.63). All other genotype combinations showed no differential response to naltrexone. Diarrhea/abdominal pain was more prominent in OPRM1 A homozygotes who were also DAT 9 or COMT met carriers.

CONCLUSIONS

These results suggest that individuals with AUD with a more opioid-responsive genotype (OPRM1 G carriers) respond better to naltrexone if they have genotypes indicating normal/less dopamine tone (DAT1 10,10 or COMT val,val), while those with a less responsive opioid-responsive genotype (OPRM1 A homozygotes) respond better to naltrexone if they have genotypes indicating greater dopamine tone (DAT1 9-repeat or COMT met carriers). These results could lead to more personalized AUD treatments.

Nicotine-Use/Smoking Is Associated with the Efficacy of Naltrexone in the Treatment of Alcohol Dependence

BACKGROUND

The opioid antagonist naltrexone is not efficacious for every alcohol treatment seeker. However, various individual factors, such as genetic differences and nicotine-use/smoking status, have been suggested as predictors of naltrexone response. In a randomized clinical trial, we previously reported that nicotine-use/smoking status might be a stronger predictor of naltrexone efficacy than OPRM1 A118G single nucleotide polymorphism (SNP) genotype. In this report, we further characterize the nicotine-users in that trial, examine other drinking outcomes, examine the influence of smoking change on naltrexone effects on drinking, and validate the result in smokers with disialo carbohydrate-deficient transferrin (%dCDT) change as an independent biomarker of response.

METHODS

Individuals (n = 146) meeting DSM-IV criteria for alcohol dependence who were genotyped for the OPRM1 A118G SNP and who did, or did not, use nicotine/cigarettes were randomized, in a balanced fashion, to naltrexone (50 mg/d) or placebo and provided medical management (MM) over a 16-week clinical trial. Alcohol use and smoking during the trial were assessed and analyzed.

RESULTS

Nicotine-use/smoking status significantly interacted with medication in reducing percent heavy drinking days (PHDD) during the trial (p = 0.003), such that nicotine-users/smokers showed significantly lower PHDD on naltrexone versus placebo (p = 0.0001, Cohen's d = 0.89), while nonusers showed no significant difference between naltrexone and placebo (p = 0.95, Cohen's d = 0.02). Similar effects were shown for drinks per day and percent days drinking. The superiority of naltrexone over placebo on PHDD reduction in nicotine-users/smokers was confirmed with %dCDT (Cohen's d range 0.3 to 0.9 over the study). Naltrexone did not significantly change cigarette use in smokers, and change in use did not influence naltrexone's effect on PHDD.

CONCLUSIONS

These data confirm past findings that naltrexone is more efficacious in those who use nicotine/cigarettes. Compared to previous work on the OPRM1 A118G SNP, it appears that nicotine-use might be a more salient predictor of naltrexone treatment response. While naltrexone did not change cigarette use during the study, and smoking change was not related to alcohol reduction, it should be noted that participants were not seeking smoking cessation and MM did not address this issue.

Aripiprazole Suppression of Drinking in a Clinical Laboratory Paradigm: Influence of Impulsivity and Self-Control

BACKGROUND

Aspects of impulsivity have been implicated in the development, or maintenance, of alcohol use disorder (AUD). The brain dopamine system is implicated in both reward processing/memory (typically subcortical) and in brain inhibitory control mechanisms (typically cortical). Using a validated clinical laboratory paradigm, the dopamine/serotonin "stabilizing" drug, aripiprazole was evaluated in non-treatment-seeking AUD individuals based on their level of impulsivity/self-control.

METHODS

Ninety-nine individuals (77% male; mean age 27; 7.5 drinks per day; 83% heavy drinking days) meeting DSM-IV criteria for alcohol dependence were randomized to aripiprazole (N = 47 evaluable) or placebo (N = 48 evaluable) based on their Barratt Impulsiveness Scale (BIS-11) score (above or below 68). Aripiprazole, or similar placebo, was titrated to 15 mg over 8 days. Drinking was recorded over 6 days under natural conditions. On Day 8, after 1 day of required abstinence, individuals participated in a bar laboratory paradigm that included a priming drink (breath alcohol concentration [BAC] target 0.02 to 0.03 g/dl) and free-choice consumption of up to 8 drinks (max BAC 0.1 g/dl) in exchange for a "bar credit" of $2 per drink (max $16). End points were drinks per day under natural conditions and drinks consumed in the bar laboratory after the priming drink.

RESULTS

There was no significant main effect of aripiprazole or interaction with BIS-11 score during the natural drinking period. However, there was a main effect of aripiprazole on bar laboratory drinking (p = 0.04) and aripiprazole reduced the total number of drinks consumed more among individuals with low self-control (p = 0.034) and increased latency to consume those drinks (p = 0.045) more among those with high impulsivity. Relative to placebo, aripiprazole caused more side effects and increased alcohol-induced sedation, but neither significantly influenced its interaction with impulsivity/self-control scores on drinking.

CONCLUSIONS

This paradigm forced a choice between immediate drinking reward and delayed monetary reward. In those with high impulsivity and/or low self-control, aripiprazole shifts the balance away from immediate drinking toward a later reward. Medications targeting cortical dopamine/serotonin balance might show clinical benefit of reduced drinking, among individuals with impulsivity/low self-control.

Differential potassium channel gene regulation in BXD mice reveals novel targets for pharmacogenetic therapies to reduce heavy alcohol drinking

Alcohol (ethanol) dependence is a chronic relapsing brain disorder partially influenced by genetics and characterized by an inability to regulate harmful levels of drinking. Emerging evidence has linked genes that encode K_V7, K_IR, and K_Ca2 K⁺ channels with variation in alcohol-related behaviors in rodents and humans. This led us to experimentally test relations between K⁺ channel genes and escalation of drinking in a chronic-intermittent ethanol (CIE) exposure model of dependence in BXD recombinant inbred strains of mice. Transcript levels for K⁺ channel genes in the prefrontal cortex (PFC) and nucleus accumbens (NAc) covary with voluntary ethanol drinking in a non-dependent cohort. Transcripts that encode K_V7 channels covary negatively with drinking in non-dependent BXD strains. Using a pharmacological approach to validate the genetic findings, C57BL/6J mice were allowed intermittent access to ethanol to establish baseline consumption before they were treated with retigabine, an FDA-approved K_V7 channel positive modulator. Systemic administration significantly reduced drinking, and consistent with previous evidence, retigabine was more effective at reducing voluntary consumption in high-drinking than low-drinking subjects. We evaluated the specific K⁺ channel genes that were most sensitive to CIE exposure and identified a gene subset in the NAc and PFC that were dysregulated in the alcohol-dependent BXD cohort. CIE-induced modulation of nine genes in the NAc and six genes in the PFC covaried well with the changes in drinking induced by ethanol dependence. Here we identified novel candidate genes in the NAc and PFC that are regulated by ethanol dependence and correlate with voluntary drinking in non-dependent and dependent BXD mice. The findings that Kcnq expression correlates with drinking and that retigabine reduces consumption suggest that K_V7 channels could be pharmacogenetic targets to treat individuals with alcohol addiction.

Phenotype-dependent inhibition of glutamatergic transmission on nucleus accumbens medium spiny neurons by the abused inhalant toluene

Abused inhalants are voluntarily inhaled at high concentrations to produce intoxicating effects. Results from animal studies show that the abused inhalant toluene triggers behaviors, such as self-administration and conditioned place preference, which are commonly associated with addictive drugs. However, little is known about how toluene affects neurons within the nucleus accumbens (NAc), a brain region within the basal ganglia that mediates goal-directed behaviors and is implicated in the development and maintenance of addictive behaviors. Here we report that toluene inhibits a component of the after-hyperpolarization potential, and dose-dependently inhibits N-methyl-D-aspartate (NMDA)-mediated currents in rat NAc medium spiny neurons (MSN). Moreover, using the multivariate statistical technique, partial least squares discriminative analysis to analyze electrophysiological measures from rat NAc MSNs, we show that toluene induces a persistent depression of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-mediated currents in one subtype of NAc MSNs, and that the electrophysiological features of MSN neurons predicts their sensitivity to toluene. The CB1 receptor antagonist AM281 blocked the toluene-induced long-term depression of AMPA currents, indicating that this process is dependent on endocannabinoid signaling. The neuronal identity of recorded cells was examined using dual histochemistry and shows that toluene-sensitive NAc neurons are dopamine D2 MSNs that express preproenkephalin mRNA. Overall, the results from these studies indicate that physiological characteristics obtained from NAc MSNs during whole-cell patch-clamp recordings reliably predict neuronal phenotype, and that the abused inhalant toluene differentially depresses excitatory neurotransmission in NAc neuronal subtypes.

The potential utility of drinking motive questions to screen at-risk drinking in socially anxious patients

BACKGROUND

Drinking motives are thought to be important mediators of the relationship between social anxiety and alcohol use. This project evaluates whether specific drinking motives accurately reflect alcohol dependence. If so, brief questions about drinking motives could serve as valuable alcohol screening tools with socially anxious patients.

METHODS

This investigation was a secondary analysis of an existing data set of 83 subjects with social anxiety disorder and at-risk alcohol use. The relationship between Drinking Motives Questionnaire (DMQ-R-5) subscales and alcohol dependence was evaluated.

RESULTS

Coping-Depression was the only subscale that contributed to the unique prediction of a diagnosis of alcohol dependence. Additionally, two items (i.e. "to cheer up when you're in a bad mood" and "to forget painful memories") predicted a diagnosis of alcohol dependence above and beyond their association with each other.

CONCLUSIONS

Among patients with social anxiety, two specific questions on the DMQ-R-5 could provide a useful screen for health professionals to predict alcohol dependence. It may be fruitful to specifically target the motives of "to cheer up when you're in a bad mood" and "to forget painful memories" when providing advice during brief interventions.

Modeling longitudinal drinking data in clinical trials: an application to the COMBINE study

BACKGROUND

There is a lack of consensus in the literature as to how to define drinking outcomes in clinical trials. Typically, separate statistical models are fit to assess treatment effects on several summary drinking measures. These summary measures do not capture the complexity of drinking behavior. We used the COMBINE study to illustrate a statistical approach for examining treatment effects on high-resolution drinking data.

METHODS

This is a secondary data analysis of COMBINE participants randomly assigned to naltrexone, acamprosate, with medical management and/or combined behavioral intervention (CBI). Using a Poisson hurdle model, abstinence and number of drinks were simultaneously modeled as a function of treatment and covariates. An emphasis was placed on the evaluation of "risky drinking" (3 drinks/day for women and 4 for men).

RESULTS

During treatment, naltrexone increased the odds of abstinence vs placebo naltrexone (OR=1.35 [1.06, 1.65]) but receiving CBI in addition to naltrexone (vs not) obscured this effect; thus, the naltrexone effect was largest in the group not receiving CBI (OR=1.87 [1.29, 2.46]). Naltrexone vs placebo naltrexone also reduced the risk of drinking in those who resumed risky drinking (RR=0.58 [0.24, 0.93]) and increased the odds of maintaining low risk drinking (OT=1.99 [1.07, 2.90]). Both effects were strongest in the absence of CBI when only "medical management" was provided.

CONCLUSIONS

The hurdle model is an appropriate statistical tool for assessing the effect of treatment on the two part drinking process, abstinence and number of drinks. When applied to COMBINE, results bolster the use of naltrexone in promoting abstinence and reduction in risky drinking.

Effects of a GABA-ergic medication combination and initial alcohol withdrawal severity on cue-elicited brain activation among treatment-seeking alcoholics

RATIONALE

Many studies have reported medication effects on alcohol cue-elicited brain activation or associations between such activation and subsequent drinking. However, few have combined the methodological rigor of a randomized clinical trial (RCT) with follow-up assessments to determine whether cue-elicited activation predicts relapse during treatment, the crux of alcoholism.

OBJECTIVES

This study analyzed functional magnetic resonance imaging (fMRI) data from 48 alcohol-dependent subjects enrolled in a 6-week RCT of an investigational pharmacotherapy.

METHODS

Subjects were randomized, based on their level of alcohol withdrawal (AW) at study entry, to receive either a combination of gabapentin (GBP; up to 1,200 mg for 39 days) and flumazenil (FMZ) infusions (2 days) or two placebos. Midway through the RCT, subjects were administered an fMRI alcohol cue reactivity task.

RESULTS

There were no main effects of medication or initial AW status on cue-elicited activation, but these factors interacted, such that the GBP/FMZ/higher AW and placebo/lower AW groups, which had previously been shown to have relatively reduced drinking, demonstrated greater dorsal anterior cingulate cortex (dACC) activation to alcohol cues. Further analysis suggested that this finding represented differences in task-related deactivation and was associated with greater control over alcohol-related thoughts. Among study completers, regardless of medication or AW status, greater left dorsolateral prefrontal cortex (DLPFC) activation predicted more post-scan heavy drinking.

CONCLUSIONS

These data suggest that alterations in task-related deactivation of dACC, a component of the default mode network, may predict better alcohol treatment response, while activation of DLPFC, an area associated with selective attention, may predict relapse drinking.

A double-blind placebo-controlled trial of N-acetylcysteine in the treatment of cocaine dependence

BACKGROUND

There remains no FDA approved medication for the treatment of cocaine dependence. Preclinical studies and early pilot clinical investigations have suggested that N-acetylcysteine (NAC) may be useful in the treatment of the disorder.

OBJECTIVE

The present report assessed the efficacy of NAC in the treatment of cocaine dependence.

METHODS

Cocaine-dependent volunteers (n = 111) were randomized to receive daily doses of 1,200 mg of NAC, 2,400 mg of NAC, or placebo. Participants were followed for 8 weeks (up to three visits weekly). At each of these visits, urine samples were collected, along with self-reports of cocaine use. Urine samples were assessed for quantitative levels of benzoylecognine (ie, cocaine metabolite).

RESULTS

Overall, the primary results for the clinical trial were negative. However, when considering only subjects who entered the trial having already achieved abstinence, results favored the 2,400 mg NAC group relative to placebo, with the 2,400 mg group having longer times to relapse and lower craving ratings.

CONCLUSION

While the present trial failed to demonstrate that NAC reduces cocaine use in cocaine-dependent individuals actively using, there was some evidence it prevented return to cocaine use in individuals who had already achieved abstinence from cocaine.

SCIENTIFIC SIGNIFICANCE

N-acetylcysteine may be useful as a relapse prevention agent in abstinent cocaine-dependent individuals.

Interacting effects of naltrexone and OPRM1 and DAT1 variation on the neural response to alcohol cues

Variation at a single nucleotide polymorphism in the μ-opioid receptor gene (OPRM1), A118G (Asn40Asp), may moderate naltrexone (NTX) effects in alcohol dependence. Both NTX and A118G variation have also been reported to affect alcohol cue-elicited brain activation. This study investigated whether sub-acute NTX treatment and A118G genotype interacted in their effects on cue-elicited activation of the ventral striatum (VS), medial prefrontal cortex (mPFC), and orbitofrontal cortex (OFC). Secondarily, variation at a variable number tandem repeat polymorphism in the dopamine transporter gene (DAT1/SLC6A3), which has been associated with increased reward-related activation in VS, was analyzed as a moderator of medication and A118G effects. Seventy-four non-treatment-seeking alcohol-dependent individuals, half preselected to carry at least one copy of the A118G G (Asp) allele, were randomized to NTX (50 mg) or placebo for 7 days, and performed an fMRI alcohol cue reactivity task on day 6. Region-of-interest analyses indicated no main effects of medication or A118G genotype. However, these factors interacted in their effects on OFC activation, such that, among NTX-treated individuals, G-allele carriers had less activation than A-allele homozygotes. DAT1 variation also moderated medication/A118G effects. There was a three-way interaction between medication and A118G and DAT1 genotypes on VS activation, such that, among G-allele carriers who received NTX, DAT1 10-repeat-allele (10R) homozygotes had less activation than 9-repeat-allele (9R) carriers. Further, 10R homozygotes who received NTX had less mPFC activation than 9R carriers. Polymorphic variation in OPRM1 and DAT1 should be considered in future studies of NTX, particularly regarding its effects on reward processing.

Interactive effects of methylphenidate and alcohol on discrimination, conditioned place preference and motor coordination in C57BL/6J mice

INTRODUCTION

Prior research indicates methylphenidate (MPH) and alcohol (ethanol, EtOH) interact to significantly affect responses humans and mice. The present studies tested the hypothesis that MPH and EtOH interact to potentiate ethanol-related behaviors in mice.

METHODS

We used several behavioral tasks including: drug discrimination in MPH-trained and EtOH-trained mice, conditioned place preference (CPP), rota-rod and the parallel rod apparatus. We also used gas chromatographic methods to measure brain tissue levels of EtOH and the D- and L-isomers of MPH and the metabolite, ethylphenidate (EPH).

RESULTS

In discrimination, EtOH (1 g/kg) produced a significant leftward shift in the MPH generalization curve (1-2 mg/kg) for MPH-trained mice, but no effects of MPH (0.625-1.25 mg/kg) on EtOH discrimination in EtOH-trained mice (0-2.5 g/kg) were observed. In CPP, the MPH (1.25 mg/kg) and EtOH (1.75 g/kg) combination significantly increased time on the drug paired side compared to vehicle (30.7 %), but this was similar to MPH (28.8 %) and EtOH (33.6 %). Footslip errors measured in a parallel rod apparatus indicated that the drug combination was very ataxic, with footslips increasing 29.5 % compared to EtOH. Finally, brain EtOH concentrations were not altered by 1.75 g/kg EtOH combined with 1.25 mg/kg MPH. However, EtOH significantly increased D-MPH and L-EPH without changing L-MPH brain concentrations.

CONCLUSIONS

The enhanced behavioral effects when EtOH is combined with MPH are likely due to the selective increase in brain D-MPH concentrations. These studies are consistent with observations in humans of increased interoceptive awareness of the drug combination and provide new clinical perspectives regarding enhanced ataxic effects of this drug combination.

Hair ethyl glucuronide is highly sensitive and specific for detecting moderate-to-heavy drinking in patients with liver disease

AIMS

Hair ethyl glucuronide (EtG) is a promising biomarker of moderate-to-heavy alcohol consumption and may have utility in detecting and monitoring alcohol use in clinical populations where alcohol use is of particular importance. This study evaluated the relationship between hair EtG and drinking in patients with liver disease.

METHODS

The subjects (n = 200) were patients with liver disease who presented for care at a university medical center. Alcohol use during the 3 months preceding participation in the study was assessed, and a sample of hair was obtained for EtG testing. Classification of drinking status (any drinking or averaging at least 28 g per day) by hair EtG was evaluated, as well as the effects of liver disease severity and demographic and hair care factors.

RESULTS

The area under the receiver operating characteristic curve for detecting an average of 28 g or more per day during the prior 90 days was 0.93. The corresponding sensitivity and specificity of hair EtG ≥8 pg/mg for averaging at least 28 g of ethanol per day were 92 and 87%, respectively. Cirrhosis and gender may have a modest influence on the relationship between drinking and hair EtG.

CONCLUSION

Hair EtG was highly accurate in differentiating subjects with liver disease averaging at least 28 g of ethanol per day from abstainers and lighter drinkers.

Naltrexone modification of drinking effects in a subacute treatment and bar-lab paradigm: influence of OPRM1 and dopamine transporter (SLC6A3) genes

BACKGROUND

Naltrexone is moderately effective for the treatment of alcohol dependence, but there is great individual variability. The opioid receptor (OPRM1) single nucleotide polymorphism (SNP) asn40asp has been shown to alter alcohol and naltrexone response in animals and humans. In addition, the brain opioid and dopamine systems interact and might underlie drinking and craving. This study investigated the effects of the OPRM1 SNP and dopamine transporter (DAT) variable number of tandem repeat (VNTR) genetic differences on drinking, alcohol effects, and naltrexone response under controlled conditions in nontreatment-seeking alcoholics.

METHODS

Two hundred and sixty-five nontreatment-seeking individuals with alcohol dependence were genotyped a priori for the OPRM1 asn40asp SNP and post hoc for DAT (SLC6A3) 9 and 10 VNTRs. Asp40 carriers (n = 43) and matched asn40 homozygotes (n = 40) were randomized to naltrexone or placebo for 7 days before receiving a priming drink and limited-access alcohol consumption in a bar-lab setting. Effects of genotypes on natural drinking as well as drinking, alcohol effects, and response to naltrexone in the bar-lab setting were examined by genotype.

RESULTS

There were no significant main effects of naltrexone or OPRM1 genotype, or any medication by OPRM1 interaction, on drinking variables. However, in individuals who had at least one DAT 9 VNTR, and who were also OPRM1 asn40 homozygotes, naltrexone reduced drinks/d consumed under natural conditions (p = 0.006), but not in the bar-lab. OPRM1 asn40 homozygotes (p = 0.028) and DAT 9 VNTR carriers (p = 0.032) had more stimulation to alcohol after the priming drink.

CONCLUSIONS

This study does not support a salient role for the OPRM1 asp40 alone in predicting drinking or naltrexone effects. However, although exploratory and in need of replication, it introduces the possibility that epistasis between the OPRM1 gene and DAT gene might need to be taken into account when examining differential genetic response to alcohol or medication treatment, especially in early-stage alcoholics.

NR2B-deficient mice are more sensitive to the locomotor stimulant and depressant effects of ethanol

The NR2B subunit of N-methyl d-aspartate glutamate receptors influences pharmacological properties and confers greater sensitivity to the modulatory effects of ethanol. This study examined behavioral responses to acute ethanol in a conditional knockout mouse model that allowed for a delayed genetic deletion of the NR2B subunit to avoid mouse lethality. Mice lacking the NR2B gene (knockout) were produced by mating NR2B[f/f] mice with CAMKIIa-driven tTA transgenic mice and the tetO-CRE transgenic mice. Adult male and female offspring representing each of the resultant genotypes (knockout, CAM, CRE and wildtype mice) were tested for open-field locomotor activity following acute low- and high-dose ethanol challenge as well as loss of righting reflex. Findings indicate that male and female mice lacking the NR2B subunit exhibited greater overall activity in comparison to other genotypes during the baseline locomotor activity test. NR2B knockout mice exhibited an exaggerated stimulant response to 1.5 g/kg (i.p.) and an exaggerated depressant response to 3.0 g/kg (i.p.) ethanol challenge. In addition, NR2B knockout mice slept longer following a high dose of ethanol (4.0 g/kg, i.p.). To evaluate pharmacokinetics, clearance rates of ethanol (1.5, 4.0 g/kg, i.p.) were measured and showed that female NR2B knockouts had a faster rate of metabolism only at the higher ethanol dose. Western blot analyses confirmed significant reduction in NR2B expression in the forebrain of knockout mice. Collectively, these data indicate that the NR2B subunit of the N-methyl d-aspartate glutamate receptor is involved in regulating low-dose stimulant effects of ethanol and the depressant/hypnotic effects of ethanol.

Gabapentin combined with naltrexone for the treatment of alcohol dependence

OBJECTIVE

Naltrexone, an efficacious medication for alcohol dependence, does not work for everyone. Symptoms such as insomnia and mood instability that are most evident during early abstinence might respond better to a different pharmacotherapy. Gabapentin may reduce these symptoms and help prevent early relapse. This clinical trial evaluated whether the combination of naltrexone and gabapentin was better than naltrexone alone and/or placebo during the early drinking cessation phase (first 6 weeks), and if so, whether this effect persisted.

METHOD

A total of 150 alcohol-dependent individuals were randomly assigned to a 16-week course of naltrexone alone (50 mg/day [N=50]), naltrexone (50 mg/day) with gabapentin (up to 1,200 mg/day [N=50]) added for the first 6 weeks, or double placebo (N=50). All participants received medical management.

RESULTS

During the first 6 weeks, the naltrexone-gabapentin group had a longer interval to heavy drinking than the naltrexone-alone group, which had an interval similar to that of the placebo group; had fewer heavy drinking days than the naltrexone-alone group, which in turn had more than the placebo group; and had fewer drinks per drinking day than the naltrexone-alone group and the placebo group. These differences faded over the remaining weeks of the study. Poor sleep was associated with more drinking in the naltrexone-alone group but not in the naltrexone-gabapentin group, while a history of alcohol withdrawal was associated with better response in the naltrexone-gabapentin group.

CONCLUSIONS

The addition of gabapentin to naltrexone improved drinking outcomes over naltrexone alone during the first 6 weeks after cessation of drinking. This effect did not endure after gabapentin was discontinued.

Neurocognitive performance, alcohol withdrawal, and effects of a combination of flumazenil and gabapentin in alcohol dependence

BACKGROUND

Among some alcohol-dependent individuals, early alcohol abstinence is marked by alcohol withdrawal (AW), a phenomenon mediated by GABA and glutamate signaling. We previously reported that a combination of 2 medications that affect GABA and glutamate tone, gabapentin and flumazenil, more effectively reduced drinking among individuals with higher pretreatment AW (Anton et al., 2009). This study evaluated whether this finding is related to changes in neurocognitive performance, which is also affected by cortical GABA and glutamate tone.

METHODS

Neurocognitive performance was assessed at baseline and twice during the first week of treatment among 60 alcohol-dependent participants in the previously published clinical trial.

RESULTS

AW was associated with poorer baseline performance on 4 of 8 measures, and individuals with higher baseline AW who received the gabapentin and flumazenil combination demonstrated greater improvement on a measure of response inhibition than those with lower AW or those who received a combination of placebos. Improvement in response inhibition during the first week and medication group interacted in their effect on subsequent drinking, such that improvement predicted greater abstinence only among individuals who received gabapentin and flumazenil. Improvement on other neurocognitive measures was neither differentially impacted by medication or baseline AW nor related to subsequent drinking.

CONCLUSIONS

Taken together, these data suggest that acute AW accounts for a small proportion of variance in neurocognitive performance, that gabapentin and flumazenil slightly improve response inhibition during early abstinence, and that such improvement may somewhat reduce later drinking. However, these medications may not affect other neurocognitive domains.

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.

Effects of brain-derived neurotrophic factor on dopaminergic function and motor behavior during aging

Brain-derived neurotrophic factor (BDNF) is critical in synaptic plasticity and in the survival and function of midbrain dopamine neurons. In this study, we assessed the effects of a partial genetic deletion of BDNF on motor function and dopamine (DA) neurotransmitter measures by comparing Bdnf(+/-) with wildtype mice (WT) at different ages. Bdnf(+/-) and WT mice had similar body weights until 12 months of age; however, at 21 months, Bdnf(+/-) mice were significantly heavier than WT mice. Horizontal and vertical motor activity was reduced for Bdnf(+/-) compared to WT mice, but was not influenced by age. Performance on an accelerating rotarod declined with age for both genotypes and was exacerbated for Bdnf(+/-) mice. Body weight did not correlate with any of the three behavioral measures studied. Dopamine neurotransmitter markers indicated no genotypic difference in striatal tyrosine hydroxylase, DA transporter (DAT) or vesicular monoamine transporter 2 (VMAT2) immunoreactivity at any age. However, DA transport via DAT (starting at 12 months) and VMAT2 (starting at 3 months) as well as KCl-stimulated DA release were reduced in Bdnf(+/-) mice and declined with age suggesting an increasingly important role for BDNF in the release and uptake of DA with the aging process. These findings suggest that a BDNF expression deficit becomes more critical to dopaminergic dynamics and related behavioral activities with increasing age.

Gender differences in alcohol treatment: an analysis of outcome from the COMBINE study

BACKGROUND

Relatively few studies have examined gender differences in the effectiveness of specific behavioral or pharmacologic treatment of alcohol dependence. The aim of this study is to assess whether there were gender differences in treatment outcomes for specific behavioral and medication treatments singly or in combination by conducting a secondary analysis of public access data from the national, multisite NIAAA-sponsored COMBINE study.

METHODS

The COMBINE study investigated alcohol treatment among 8 groups of patients (378 women, 848 men) who received medical management (MM) with 16 weeks of placebo, naltrexone (100 mg/day), acamprosate (3 g/day), or their combination with or without a specialist-delivered combined behavioral intervention. We examined efficacy measures separately for men and women, followed by an overall analysis that included gender and its interaction with treatment condition in the analyses. These analyses were performed to confirm whether the findings reported in the parent trial were also relevant to women, and to more closely examine secondary outcome variables that were not analyzed previously for gender effects.

RESULTS

Compared to men, women reported a later age of onset of alcohol dependence by approximately 3 years, were significantly less likely to have had previous alcohol treatment, and drank fewer drinks per drinking day. Otherwise, there were no baseline gender differences in drinking measures. Outcome analyses of 2 primary (percent days abstinent and time to first heavy drinking day) and 2 secondary (good clinical response and percent heavy drinking days) drinking measures yielded the same overall pattern in each gender as that observed in the parent COMBINE study report. That is, only the naltrexone by behavioral intervention interaction reached or approached significance in women as well as in men. There was a naltrexone main effect that was significant in both men and women in reduction in alcohol craving scores with naltrexone-treated subjects reporting lower craving than placebo-treated subjects.

CONCLUSIONS

This gender-focused analysis found that alcohol-dependent women responded to naltrexone with COMBINE's Medical Management, similar to the alcohol-dependent men, on a wide range of outcome measures. These results suggest that clinicians can feel comfortable prescribing naltrexone for alcohol dependence in both men and women. In this study, it is also notable that fewer women than men reported receiving any alcohol treatment prior to entry into the COMBINE study. Of note, women tend to go to primary health care more frequently than to specialty substance abuse programs for treatment, and so the benefit we confirm for women of the naltrexone and MM combination has practical implications for treating alcohol-dependent women.

12-Step Therapy and Women with and without Social Phobia: A Study of the Effectiveness of 12-Step Therapy to Facilitate AA Engagement

Alcoholism treatment often encourages involvement in Alcoholics Anonymous (AA). Little provision is made for women with social phobia (SP), who have been reported to have worse outcomes in twelve-step-facilitation (TSF) relative to cognitive behavioral therapy. This study examined whether SP moderated the effects of gender for these women in TSF. 133 SP alcoholics assigned to TSF (35 females and 98 males) in Project MATCH were compared to a non-SP control group. SP women drank earlier and more intensely than non-SP women and all males, had equivalent AA attendance and completion of Step 5, and were less likely to acquire a sponsor during TSF.

Phosphatidylethanol and alcohol consumption in reproductive age women

BACKGROUND

Fetal alcohol disorders are preventable, but self-reported alcohol consumption can be misleading and impede effective treatment. Biomarkers represent an alternative method for assessing alcohol use, and this study evaluated the relationship between blood phosphatidylethanol (PEth) and alcohol use in a sample of reproductive age women.

METHODS

Alcohol use was estimated by validated self-report methods in 80 nonpregnant women ages 18 to 35. PEth was measured by a contracted laboratory using a liquid chromatography-tandem mass spectrometry assay. Regression methods appropriate for the distribution of PEth were used to define its relationship to alcohol consumption during the prior 2 weeks and explore the effects of drinking patterns on this association. Receiver operating characteristic analysis was used to estimate the sensitivity of PEth for various drinking levels at 95% specific cutoffs.

RESULTS

PEth had a positive linear association with grams of alcohol consumed (p < 0.001), and was detectable in 93% of subjects consuming an average of 2 or more drinks per day. The relationship between total alcohol consumption and PEth may be stronger in women with recent heavy drinking days. The relationship between drinking and PEth varied considerably between individuals, and sensitivity for a certain amount of drinking was low at a highly specific cutoff concentration.

CONCLUSIONS

PEth is a highly sensitive indicator of moderate and heavy alcohol consumption in reproductive age women and may complement the use of self-report alcohol screens when additional objective markers of alcohol use are desirable. However, choosing a highly valid cutoff concentration for PEth to differentiate various levels of alcohol consumption may not be feasible.

A double-blind trial of gabapentin versus lorazepam in the treatment of alcohol withdrawal

INTRODUCTION

Some anticonvulsants ameliorate signs and symptoms of alcohol withdrawal, but have an unacceptable side effect burden. Among the advantages of using anticonvulsant agents in this capacity is their purported lack of interaction with alcohol that could increase psychomotor deficits, increase cognitive impairment, or increase intoxication. The aim of this study was to evaluate alcohol use and symptom reduction of gabapentin when compared with lorazepam in the treatment of alcohol withdrawal in a double-blinded randomized clinical trial.

METHODS

One hundred individuals seeking outpatient treatment of alcohol withdrawal with Clinical Institute Withdrawal Assessment for Alcohol-Revised (CIWA-Ar) ratings > or =10 were randomized to double-blind treatment with 2 doses of gabapentin (900 mg tapering to 600 mg or 1200 tapering to 800 mg) or lorazepam (6 mg tapering to 4 mg) for 4 days. Severity of alcohol withdrawal was measured by the CIWA-Ar on days 1 to 4 of treatment and on days 5, 7, and 12 post-treatment and alcohol use monitored by verbal report and breath alcohol levels.

RESULTS

CIWA-Ar scores decreased over time in all groups; high-dose gabapentin was statistically superior but clinically similar to lorazepam (p = 0.009). During treatment, lorazepam-treated participants had higher probabilities of drinking on the first day of dose decrease (day 2) and the second day off medication (day 6) compared to gabapentin-treated participants (p = 0.0002). Post-treatment, gabapentin-treated participants had less probability of drinking during the follow-up post-treatment period (p = 0.2 for 900 mg and p = 0.3 for 1200 mg) compared to the lorazepam-treated participants (p = 0.55). The gabapentin groups also had less craving, anxiety, and sedation compared to lorazepam.

CONCLUSIONS

Gabapentin was well tolerated and effectively diminished the symptoms of alcohol withdrawal in our population especially at the higher target dose (1200 mg) used in this study. Gabapentin reduced the probability of drinking during alcohol withdrawal and in the immediate postwithdrawal week compared to lorazepam.

Preliminary evaluation of phosphatidylethanol and alcohol consumption in patients with liver disease and hypertension

AIMS

The goal of this preliminary study was to evaluate the relationship between blood phosphatidylethanol (PEth) and recent drinking in patients with liver disease and hypertension.

METHODS

Twenty-one patients with liver disease and 21 patients with essential hypertension were recruited at an academic medical center. Alcohol consumption was estimated using validated self-report methods, and blood PEth was measured by HPLC-MS/MS at a contracted laboratory. Nonparametric comparisons were made between abstainers/light drinkers, moderate drinkers consuming between 1 and 3 drinks per day, and those drinking above this level. Regression methods were used to estimate the effects of liver disease, gender, and age on the relationship between PEth and alcohol use, and to estimate the strength of the linear relationship between PEth and drinking.

RESULTS

PEth differed significantly between the three drinking groups (P < 0.001). The relationship between PEth and alcohol did not differ between hypertension and liver disease patients (P = 0.696), nor by gender and age. While there was substantial variability between subjects in the PEth concentration given a similar level of reported drinking, the amount of ethanol consumed was strongly associated with the PEth concentration (P < 0.001).

CONCLUSION

Results support PEth measurement by HPLC-MS/MS as a promising marker of past 1- to 2-week moderate to heavy alcohol consumption in patients with and without liver disease. PEth appears useful for differentiating abstinence or light drinking from moderate to heavy consumption, but may have limited utility for differentiating moderate from heavy alcohol use.

Iso-osmolality versus low-osmolality iodinated contrast medium at intravenous contrast-enhanced CT: effect on kidney function

PURPOSE

To determine the effects of iso-osmolality contrast medium compared with a low-osmolality agent on renal function (serum creatinine [SCr] and glomerular filtration rate [GFR]) in high-risk patients undergoing intravenous contrast material-enhanced CT.

MATERIALS AND METHODS

This HIPAA-compliant study was IRB-approved; formal consent was obtained. One hundred seventeen patients (83 men, 34 women; mean age, 64.3 years; range, 18-86 years) with decreased renal function underwent contrast-enhanced CT with either iso-osmolality iodixanol (n = 61) or low-osmolality iopromide (n = 56). Outcome measures were of SCr increase or GFR decrease for 3 days after CT, a SCr increase (of >or=0.5 mg/dL [44.2 micromol/L, 25%] or >or=1.0 mg/dL [88.4 micromol/L, 50%]), a GFR reduction (of >or=5 mL/min), and patient outcome at 30- and 90-day follow-up.

RESULTS

Iodixanol decreased SCr (mean +/- standard deviation) from 1.77 mg/dL +/- 0.24 (156.47 micromol/L +/- 21.22) at baseline to 1.65 mg/dL +/- 0.35 (145.86 micromol/L +/- 30.94, P = .046) at day 1, 1.73 mg/dL +/- 0.53 (152.93 micromol/L +/- 46.85, not significant) at day 2, and 1.73 mg/dL +/- 0.55 (152.93 micromol/L +/- 48.62, not significant) at day 3 (not significant). Iopromide increased SCr from 1.75 mg/dL +/- 0.32 (154.7 micromol/L +/- 28.29) at baseline to 1.8 mg/dL +/- 0.42 (159.12 micromol/L +/- 15.59) at day 1, 1.77 mg/dL +/- 0.49 (156.47 micromol/L +/- 43.32) at day 2, and 1.77 mg/dL +/- 0.62 (156.47 micromol/L +/- 54.81) at day 3 (not significant). Iodixanol increased and iopromide decreased GFR on all 3 days after CT (not significant). Fewer patients in the iodixanol group (8.5%) than in the iopromide group (27.8%) had SCr increase 0.5 mg/dL or higher (>or=25%, P = .012). Two patients in each group had SCr increase of 1.0 mg/dL or more (not significant). More patients in the iopromide group (42.3%) than in the iodoxanol group (24.1%) had a GFR reduction of 5 mL/min or higher (P = .0426). No patient had a contrast material-related adverse event at 30- or 90-day follow-up.

CONCLUSION

Intravenous contrast material application in high-risk patients is unlikely to be associated with permanent adverse outcomes. SCr levels after contrast material administration are lower in iodixanol than iopromide groups.

Effect of naltrexone and ondansetron on alcohol cue-induced activation of the ventral striatum in alcohol-dependent people

CONTEXT

Medication for the treatment of alcoholism is currently not particularly robust. Neuroimaging techniques might predict which medications could be useful in the treatment of alcohol dependence.

OBJECTIVE

To explore the effect of naltrexone, ondansetron hydrochloride, or the combination of these medications on cue-induced craving and ventral striatum activation.

DESIGN

Functional brain imaging was conducted during alcohol cue presentation.

SETTING

Participants were recruited from the general community following media advertisement. Experimental procedures were performed in the magnetic resonance imaging suite of a major training hospital and medical research institute.

PATIENTS

Ninety non-treatment-seeking alcohol-dependent (by DSM-IV criteria) and 17 social drinking (< 14 drinks per week) paid volunteers recruited through advertisements at an academic center.

INTERVENTIONS

A taste of alcohol and a series of alcohol-related pictures, neutral beverage pictures, and visual control images were provided to volunteers after 7 days of double-blind randomly assigned daily dosing with 50 mg of naltrexone (n = 23), 0.50 mg of ondansetron hydrochloride (n = 23), the combination of the 2 medications (n = 20), or matching placebos (n = 24).

MAIN OUTCOME MEASURES

Difference in brain blood oxygen level-dependent magnetic resonance when viewing alcohol pictures vs neutral beverage pictures with a particular focus on ventral striatum activity comparison across medication groups. Self-ratings of alcohol craving.

RESULTS

The combination treatment decreased craving for alcohol. Naltrexone with (P = .02) or without (P = .049) ondansetron decreased alcohol cue-induced activation of the ventral striatum. Ondansetron by itself was similar to naltrexone and the combination in the overall analysis but intermediate in a region-specific analysis.

CONCLUSIONS

Consistent with animal data that suggest that both naltrexone and ondansetron reduce alcohol-stimulated dopamine output in the ventral striatum, the current study found evidence that these medications, alone or in combination, could decrease alcohol cue-induced activation of the ventral striatum, consistent with their putative treatment efficacy.

Improving acceptance of naltrexone in community addiction treatment centers: a pilot study

Alcoholism pharmacotherapies are underused in community addiction treatment settings, in part because individuals who practice in these settings--nonmedical addiction counselors and administrators--lack knowledge about and confidence in the value of adjunctive alcohol pharmacotherapies. We developed and tested an intervention to improve knowledge and attitudes about naltrexone. A team of researchers, physicians, addiction treatment counselors, and administrators collaborated to develop a naltrexone educational intervention designed for nonmedical addiction professionals. The intervention was compared with a control condition in a pilot study with 6 addiction treatment agencies (3 agencies per group). Participants (counselors and administrators, N = 84) were assessed before and 6 months after the intervention. Results revealed that the intervention significantly improved naltrexone knowledge, and participants who received the intervention reported greater satisfaction with the education they received, as well as greater use of the information. The effect of the intervention on attitudes about naltrexone was encouraging but did not to reach statistical significance. This study is the first reported attempt to develop and test an intervention specifically to improve acceptance of adjunctive medications for alcoholism among nonmedical addiction professionals.

Paroxetine reduces social anxiety in individuals with a co-occurring alcohol use disorder

Patients with social anxiety disorder who are seen in clinical practice commonly have additional psychiatric comorbidity, including alcohol use disorders. The first line treatment for social anxiety disorder is selective-serotonin-reuptake-inhibitors (SSRIs), such as paroxetine. However, the efficacy of SSRIs has been determined with studies that excluded alcoholics. Forty two subjects with social anxiety and a co-occurring alcohol use disorder participated in a 16-week, double-blind, placebo-controlled clinical trial to determine the efficacy of paroxetine for social anxiety in patients with co-occurring alcohol problems. Paroxetine was superior to placebo in reducing social anxiety, as measured by the Liebowitz Social Anxiety Scale total and subscale scores and additional measures of social anxiety. This study provides the first evidence-based recommendation for the use of an SSRI to treat social anxiety in this patient population.

Appetitive nature of drug cues re-confirmed with physiological measures and the potential role of stage of change

RATIONALE

Smokers report pleasant reactions to viewing cigarettes, suggesting that smoking cues may be appetitive in nature. Two studies have investigated this hypothesis through physiological assessment. The first study found that smoking cues were physiologically appetitive in nature, with dampened startle response to smoking pictures in comparison to neutral pictures. The second found that smoking pictures did not modulate the startle response, suggesting such cues may not be physiologically appetitive.

OBJECTIVE

The goal of the present study was to further investigate how participants' motivation to quit smoking might modulate responses to smoking cues.

MATERIALS AND METHODS

Twenty-two nicotine-dependent smokers viewed standardized pleasant, unpleasant, neutral, and smoking pictures. Eleven of the subjects reported no intent to quit (precontemplators) and 11 reported planning to quit within the next 6 months (contemplators). Acoustic startle probes were randomly administered while subjects viewed the pictures, and eyeblink startle magnitude was measured with electromyography (EMG).

RESULTS

As a whole, participants exhibited dampened startle responses during smoking pictures, relative to unpleasant pictures. Precontemplators showed robust startle inhibition to smoking pictures, in comparison to both neutral and unpleasant pictures. Contemplators, however, showed blunted unpleasant picture augmentation and a lack of startle inhibition for pleasant pictures.

CONCLUSION

These findings are consistent with the idea that smoking pictures are appetitive in nature. Furthermore, they suggest that smokers at a later stage of change may exhibit a lesser response.

Intravenous cocaine self-administration: individual differences in male and female C57BL/6J mice

This study examined individual differences in male and female C57BL/6J (C57) mice responding for intravenous cocaine reinforcement. The experiment used 4 groups of mice, distinguished by sex and cocaine unit dose (0.3 or 1 mg/kg/infusion). Mice trained to lever respond for IV cocaine were given the drug initially on an FR2 schedule and then on a Progressive Ratio 2(PR2) schedule. Hierarchical linear modeling (HLM) techniques were used to examine data generated across four FR2 and four PR2 sessions, as well as within session data when cocaine was delivered on the PR2 schedule. HLM techniques, although uncommon in the animal literature, characterize individual differences in human studies and are likely to be useful in more complex preclinical studies. Analysis established distinct patterns of self-administration both across and within sessions. Responses for cocaine delivered on the FR2 schedule was dose-dependent, but did not differ according to sex. Response output was greater when either dose of cocaine was delivered on the PR2 than the FR2 schedule. Although response output for the more rewarding 1 mg/kg unit dose was similar for the two sexes, males responded more and had greater cocaine intake than females when the less reinforcing 0.3 mg/kg dose was delivered at the more behaviorally challenging PR2 schedule. HLM analysis of response patterns and cocaine intake within the PR2 sessions corroborated this sex difference and also indicated that trajectories differed for individual mice after accounting for the sex and dose factors. The reduced response output by females for cocaine in the present experiment is consistent with previous reports that sex differences in the rewarding effects of either alcohol or food reinforcement were revealed for C57 mice only when delivered on more behaviorally demanding schedules (e.g. PR2 or FR100).

Self-reported sleep, sleepiness, and repeated alcohol withdrawals: a randomized, double blind, controlled comparison of lorazepam vs gabapentin

STUDY OBJECTIVES

Insomnia is a central symptom of alcohol withdrawal and increases relapse potential. The primary objective of this study was to compare the efficacy of gabapentin to lorazepam in alleviating sleep disturbances and daytime sleepiness during an episode of alcohol withdrawal. The secondary objective of this study was to determine if drug treatment efficacy differed by the patient history of previous treatments for alcohol withdrawal.

METHODS

Outpatients in treatment for alcohol withdrawal received a 4-day fixed-dose taper of gabapentin or lorazepam in a double-blind, randomized, controlled trial with an 8-day follow-up. Daily across a 5 day outpatient treatment and Days 7 and 12 post-treatment, patients self-reported daytime sleepiness using the Epworth Sleepiness Scale. Self-reports of depression (Beck Depression Inventory) were completed at Days 1, 5, 7 and 12. Staff assessed daily alcohol withdrawal using the Clinical Institute Withdrawal Assessment for Alcohol. From these instruments, self-reported sleep and sleepiness were extracted and assessed in the context of limited (0-1) or multiple (2 or more) previously treated alcohol withdrawal episodes.

RESULTS

Patients with limited previous withdrawals reported similar treatment effects on self-reports of sleep and sleepiness for gabapentin and lorazepam. In contrast, patients with multiple previous alcohol withdrawals receiving gabapentin reported reduced sleep disturbances and sleepiness in comparison to those receiving lorazepam.

CONCLUSIONS

During treatment for alcohol withdrawal, gabapentin as compared to standard therapy with lorazepam, was superior on multiple sleep measures, in patients who had previous withdrawals. Lorazepam subjects experienced rebound symptoms. Early drinking was related to persisting insomnia with both drugs.

The impact of alcohol dependence and posttraumatic stress disorder on cold pressor task response

OBJECTIVE

Posttraumatic stress disorder (PTSD) is commonly comorbid with alcohol-use disorders. Abnormalities in the hypothalamic-pituitary-adrenal (HPA) axis response are common in both disorders. The objective of this study was to investigate HPA axis reactivity to the cold pressor task (CPT) among individuals with alcohol dependence, PTSD, and comorbid alcohol dependence and PTSD.

METHOD

Participants were 119 individuals with alcohol dependence only (n = 31), comorbid alcohol dependence and PTSD (n = 28), PTSD without alcohol dependence (n = 30), and a control group (n = 30). Subjective response, adrenal corticotropic hormone (ACTH), and cortisol were measured before, immediately after, and for 120 minutes after each subject completed the CPT.

RESULTS

There were significant group and gender differences found in the subjective and ACTH response, with significantly higher subjective stress ratings and decreased ACTH response in the alcohol-dependent, PTSD, and comorbid alcohol dependent-PTSD groups compared with the control group.

CONCLUSIONS

There were differences in the HPA axis and subjective response to the CPT between the control group and both the alcohol and PTSD groups. The HPA response in the comorbid alcohol-PTSD group was not significantly different than that of the alcohol-only or PTSD-only groups.

Cold pressor task reactivity: predictors of alcohol use among alcohol-dependent individuals with and without comorbid posttraumatic stress disorder

BACKGROUND

The association between stress and alcohol dependence has been well established. Abnormalities in stress reactivity and hypothalamic-pituitary-adrenal axis (HPA) function may be involved in the mechanistic connection between stress and the initiation, development, and/or maintenance of alcohol dependence. Posttraumatic stress disorder (PTSD) commonly co-occurs with alcohol dependence and is characterized by HPA axis abnormalities. This study investigated the relationship between subjective and neuroendocrine stress reactivity to the cold pressor task (CPT) and prospective alcohol use among individuals with alcohol dependence, with and without comorbid PTSD.

METHODS

Participants were 63 individuals with (a) alcohol dependence only (n=35) or (b) comorbid alcohol dependence and PTSD (n=28). Participants completed the CPT, a widely used physical laboratory stressor. Subjective stress, craving, adrenocorticotrophin (ACTH), and cortisol were measured before, immediately after, and at 5, 30, 60, and 120 minutes after the CPT. Alcohol use during 1 month following testing was also assessed.

RESULTS

For the alcohol-only group, change in craving immediately following the CPT and craving during the 120-minute recovery phase were predictive of follow-up alcohol use. For the alcohol/PTSD group, change in craving was not predictive of follow-up use. Baseline drinking was, however, predictive of followup alcohol use for the alcohol/PTSD group. For the alcohol-only group, a blunted ACTH response coupled with a higher change in craving following the CPT was associated with significantly greater frequency and intensity of drinking during the follow-up phase.

CONCLUSIONS

These preliminary findings demonstrate significant differences between the alcohol-only and the alcohol/PTSD group in predictors of relapse. For the alcohol-only group, reactivity to an acute laboratory stressor may be predictive of subsequent alcohol use. This was not true for the alcohol/PTSD group. Although preliminary, the findings may help shed light on the mechanistic relationship between stress reactivity and increased risk for alcohol relapse and dependence in individuals with and without other Axis I comorbidity.

Patterns of gene expression in the frontal cortex discriminate alcoholic from nonalcoholic individuals

Alcohol dependence is characterized by tolerance, physical dependence, and craving. The neuroadaptations underlying these effects of chronic alcohol abuse are likely due to altered gene expression. Previous gene expression studies using human post-mortem brain demonstrated that several gene families were altered by alcohol abuse. However, most of these changes in gene expression were small. It is not clear if gene expression profiles have sufficient power to discriminate control from alcoholic individuals and how consistent gene expression changes are when a relatively large sample size is examined. In the present study, microarray analysis (approximately 47,000 elements) was performed on the superior frontal cortex of 27 individual human cases (14 well characterized alcoholics and 13 matched controls). A partial least squares statistical procedure was applied to identify genes with altered expression levels in alcoholics. We found that genes involved in myelination, ubiquitination, apoptosis, cell adhesion, neurogenesis, and neural disease showed altered expression levels. Importantly, genes involved in neurodegenerative diseases such as Alzheimer's disease were significantly altered suggesting a link between alcoholism and other neurodegenerative conditions. A total of 27 genes identified in this study were previously shown to be changed by alcohol abuse in previous studies of human post-mortem brain. These results revealed a consistent re-programming of gene expression in alcohol abusers that reliably discriminates alcoholic from non-alcoholic individuals.

The relationship between women's subjective and physiological sexual arousal

Previous literature presents discordant results on the relationship between physiological and subjective sexual arousal in women. In this study, the use of hierarchical linear modeling (HLM) revealed a significant concordance between continuous measures of physiological and subjective sexual arousal as assessed during exposure to erotic stimuli in a laboratory setting. We propose that past studies that have found little or no association between the two measures may have been in part limited by the methodology and statistical analyses employed.

Gene expression profiling of individual cases reveals consistent transcriptional changes in alcoholic human brain

Chronic alcohol exposure induces lasting behavioral changes, tolerance, and dependence. This results, at least partially, from neural adaptations at a cellular level. Previous genome-wide gene expression studies using pooled human brain samples showed that alcohol abuse causes widespread changes in the pattern of gene expression in the frontal and motor cortices of human brain. Because these studies used pooled samples, they could not determine variability between different individuals. In the present study, we profiled gene expression levels of 14 postmortem human brains (seven controls and seven alcoholic cases) using cDNA microarrays (46,448 clones per array). Both frontal cortex and motor cortex brain regions were studied. The list of genes differentially expressed confirms and extends previous studies of alcohol responsive genes. Genes identified as differentially expressed in two brain regions fell generally into similar functional groups, including metabolism, immune response, cell survival, cell communication, signal transduction and energy production. Importantly, hierarchical clustering of differentially expressed genes accurately distinguished between control and alcoholic cases, particularly in the frontal cortex.

Prenatal ethanol exposure modifies [3H]MK-801 binding to NMDA receptors: spermidine and ifenprodil

BACKGROUND

It has been suggested that abnormalities seen in fetal alcohol syndrome are linked with NMDA receptor malfunction. Our laboratory has previously shown that prenatal ethanol treatment decreases [3H]MK-801 binding density at postnatal day 21, when NMDA receptor subunit protein levels were unaltered. Thus, the focus of the present study was to examine whether prenatal ethanol modifies native NMDA receptor levels.

METHODS

Cerebral cortices were taken from offspring born to three treatment groups of pregnant Sprague Dawley(R) rats: an ethanol group given an ethanol liquid diet during the gestational period, a pair-fed control group that received a liquid diet without ethanol, and an ad libitum group fed rat chow and tap water. Western blot studies were carried out at postnatal days 1, 7, 14, and 21 to examine total protein expression of NR1 and NR1b splice variants. NR2 subunit levels were examined by [3H]MK-801 binding studies using spermidine, an endogenous polyamine, and ifenprodil, a selective NR2B antagonist.

RESULTS

[3H]MK-801 binding density was significantly reduced in prenatal ethanol-treated groups compared with ad libitum and pair-fed control groups. Spermidine increased [3H]MK-801 binding, although potentiation by spermidine was not significantly different among all three experimental groups. Furthermore, no significant differences in total protein expression of NR1 or NR1b splice variants were observed in cortical membrane homogenates at postnatal days 1 through 21. [3H]MK-801 binding in the presence of ifenprodil showed that prenatal ethanol treatment significantly decreased low-affinity ifenprodil binding. High-affinity ifenprodil binding was reduced in both pair-fed and ethanol-treated groups.

CONCLUSIONS

These results suggest that prenatal ethanol treatment reduces [3H]MK-801 binding and that this reduction may be due to a decrease in NR2A subunits.

Unipolar Depression, Life Context Vulnerabilities, and Drinking to Cope

This study followed baseline samples of 424 unipolar depressed patients and 424 community controls across 10 years to investigate the association between depression and alcohol-related coping and to examine how life context vulnerabilities underlie the risk for depressed individuals to rely on drinking to cope. Findings supported all hypotheses. Depressed patients engaged in more drinking to cope than did community controls. Within individuals, more negative life events and less family support were associated with more drinking to cope across the 4 observations. Depressed patients experienced more negative life events and less family support than did community controls. These underlying life context vulnerabilities explained the relationship between depressed patient status and drinking to cope.

Methods for the identification of differentially expressed genes in human post-mortem brain

Microarrays can be used to monitor the expression of thousands of genes simultaneously. This technique requires high-quality RNA which can be extracted from a variety of tissues and cells including post-mortem human brain. Given the vast amount of information obtained from microarray studies, it is critical to establish valid analysis techniques to identify differentially expressed genes. This technical report describes the basic methodology and analyses used to identify such genes in human post-mortem brain tissue.

Acute ethanol affects phosphorylation state of the NMDA receptor complex: implication of tyrosine phosphatases and protein kinase A

Phosphorylation has been shown to regulate N-methyl-D-aspartic acid receptor (NMDAR) function. The inhibitory effect of ethanol on NMDAR function could be due, at least in part, to a change in NMDAR phosphorylation states. In order to investigate the effect of ethanol on phosphorylation of NR1 and NR2 subunits, NMDAR complexes were immunoprecipitated from cortical slices pre-exposed to ethanol. Acute ethanol, 100 and 200 mM, significantly decreased the tyrosine phosphorylation of NR2 subunits (Tyr-NR2). Treatment with a tyrosine phosphatase inhibitor reduced the inhibition of Tyr-NR2 phosphorylation caused by 100 mM ethanol. This suggests an involvement of tyrosine phosphatases in ethanol-induced inhibition of Tyr-NR2 phosphorylation. Slices pre-exposed to 100 and 200 mM ethanol exhibited a significant increase in the phosphorylation of NR1 by PKA at serine 897 (Ser897-NR1), which was blocked by a PKA inhibitor. Moreover, at 200 mM, ethanol produced a significant increase in PKA activity. Together, these results indicate that ethanol may increase Ser897-NR1 phosphorylation by activating PKA. However, ethanol did not affect phosphorylation of NR1 subunits by PKC at serine 896. We conclude that ethanol has the ability to modulate phosphorylation of both NR2 and NR1 subunits and these effects appear to implicate tyrosine phosphatases and PKA, respectively.

Drinking to cope and alcohol use and abuse in unipolar depression: a 10-year model

This study examined drinking to cope with distress and drinking behavior in a baseline sample of 412 unipolar depressed patients assessed 4 times over a 10-year period. Baseline drinking to cope operated prospectively as a risk factor for more alcohol consumption at 1-, 4-, and 10-year follow-ups and for more drinking problems at 1- and 4-year follow-ups. Findings elucidate a key mechanism in this process by showing that drinking to cope strengthened the link between depressive symptoms and drinking behavior. Individuals who had a stronger propensity to drink to cope at baseline showed a stronger connection between depressive symptoms and both alcohol consumption and drinking problems.

An examination of the decline in fear and disgust during exposure-based treatment

It has been suggested that disgust plays a prominent role in the fear of spiders. Participants (N=27) displaying marked spider fear were provided 30 min of self-directed in vivo exposure to an actual tarantula, during which time their fear and disgust levels were assessed repeatedly. Growth curve analyses were then conducted to examine the decay slopes in both fear and disgust and their relationship. Consistent with prediction, exposure led to significant declines in both spider fear and spider-specific disgust but not in global disgust sensitivity. However, the decay slope observed for fear was significantly greater than that for disgust. Further analyses revealed that the reduction in disgust during treatment remained significant even after controlling for change in fear; and similarly, change in fear remained significant even after controlling for change in disgust. Contrary to prediction, disgust levels at pretreatment did not moderate the level of fear activation or fear reduction during treatment. Theoretical and clinical implications of the findings are discussed.

Effect of dopamine D2/D3 receptor antagonist sulpiride on amphetamine-induced changes in striatal extracellular dopamine

Amphetamine increases extracellular dopamine and induces locomotor and stereotypical behaviors in rats. This study examined the effect of the dopamine D2/D3 receptor antagonist sulpiride (50 mg/kg s.c.) on the dopaminergic response to amphetamine (0.5, 2.0, or 8.0 mg/kg i.p.) in male Sprague-Dawley rats. Extracellular dopamine in the striatum was monitored using in vivo microdialysis and high performance liquid chromatography with electrochemical detection. Dopamine concentration curves were analyzed using non-linear regression and residual F-testing. Amphetamine enhanced extracellular dopamine in a dose-dependent manner. Sulpiride augmented the increase in dopamine induced by 0.5 and 2 mg/kg amphetamine by decreasing the rate of dopamine concentration fall off in the extracellular space (P<0.05). Sulpiride also potentiated the amount of dopamine increased by 8 mg/kg amphetamine, but did so by affecting the maximum concentration achieved (P<0.05), not the onset or offset rates. We conclude that the primary effect of a dopamine D2/D3 receptor antagonist is a potentiation of the effect of amphetamine on extracellular striatal dopamine levels, which may contribute to the enhanced stereotypic effects observed when paired with amphetamine.

Drinking to cope, emotional distress and alcohol use and abuse: a ten-year model

OBJECTIVE

This study examines the ability of baseline drinking to cope to predict drinking behavior across an ensuing 10-year period. In addition, it examines whether a propensity to consume alcohol to cope with stressors strengthens the link between emotional distress and drinking behavior.

METHOD

The study uses survey data from a baseline sample of 421 adults (54% women) assessed four times over a 10-year period (i.e., baseline and 1-, 4- and 10-year follow-ups).

RESULTS

Baseline drinking to cope was associated with more alcohol consumption and drinking problems at all four observations across the 10-year interval. Baseline drinking to cope also predicted increases in both alcohol consumption and drinking problems in the following year. Moreover, change in drinking to cope was positively linked to changes in both alcohol consumption and drinking problems over the interval. Individuals who had a stronger propensity to drink to cope at baseline showed a stronger link between both anxiety and depressive symptoms and drinking outcomes.

CONCLUSIONS

Findings demonstrate the power of alcohol-related coping strategies in predicting long-term drinking behavior and they illustrate one way in which such coping is linked to alcohol use and abuse. More broadly, they underscore the importance of considering individual differences in emotion-based theories of drinking behavior.

Nonlinear analysis of partial dopamine agonist effects on cAMP in C6 glioma cells

Most drugs have some efficacy so that improved methods to determine the relative intrinsic efficacy of partial agonists should be of benefit to preclinical and clinical investigators. We examined the effects of partial D(1) or partial D(2) dopamine agonists using a partial agonist interaction model. The dependent variable was the modulation of the dopamine-receptor-mediated cAMP response in C6 glioma cells selectively and stably expressing either D(1) or D(2) recombinant dopamine receptors. The dissociation constant (K(B)) and relative intrinsic efficacy (E(r)) for each partial agonist were calculated using a partial agonist interaction null model in which the effects of fixed concentrations of each partial agonist on the dopamine dose-response curve were evaluated. This model is an extension of the competitive antagonist null model to drugs with efficacy and assumes only that the log-dose--response curve is monotonic. Generally, the partial agonist interaction model fit the data, as well as fits of the independent logistic curves. Furthermore, the partial agonist K(B) values could be shared across partial agonist concentrations without worsening the model fit (by increasing the residual variance). K(B) values were also similar to drug affinities reported in the literature. The model was validated in three ways. First, we assumed a common tissue stimulus parameter (beta) and calculated the E(r) values. This provided a qualitative check on the interaction model results. Second, we calculated new relative efficacy values, E(r)(beta), using the beta estimate. Third, we calculated relative efficacy using relative maxima times midpoint shift ratios (J. Theor. Biol. 198 (1999) 347.). All three methods indicated that the present model yielded reasonable estimates of affinity and relative efficacy for the set of compounds studied. Our results provide a quick and convenient method of quantification of partial agonist efficacy. Special applications and limitations of the model are discussed. In addition, the present results are the first report of the relative intrinsic efficacy values for this set of D(2) ligands.

Dissociation between the time course of ethanol and extracellular dopamine concentrations in the nucleus accumbens after a single intraperitoneal injection

BACKGROUND

Dopamine release in the nucleus accumbens has been linked to the reinforcing effects of ethanol, but the time course or relationship of this response to ethanol concentrations in the brain has not been studied.

METHODS

Various doses of ethanol (0-2.0 g/kg) were administered intraperitoneally to male Sprague Dawley rats, and dopamine and ethanol were simultaneously analyzed in dialysate samples from the nucleus accumbens. A separate study to compare the ethanol-induced dopamine response in male and female rats was carried out by using a 1 g/kg intraperitoneal dose of ethanol.

RESULTS

In male rats, 1 and 2 g/kg ethanol significantly increased dialysate dopamine by 40% over basal, whereas 0.25 and 0.5 g/kg ethanol produced a nonsignificant 20% increase. Dialysate ethanol concentrations exhibited a curvilinear decline after reaching peak levels for the lower doses but showed a linear decrease after 1 and 2 g/kg. There was a dissociation between the time courses of extracellular dopamine and ethanol after 1 and 2 g/kg ethanol treatment. The dopamine response returned to basal within 90 min, whereas the ethanol concentrations remained elevated. In a separate study that compared male and female rats, the ratio of the dopamine response over basal to the dialysate ethanol concentrations was significantly decreased at 60 min after an injection of 1 g/kg. However, there were no differences between males and females.

CONCLUSIONS

The dissociation between dopamine and ethanol levels may reflect the development of acute tolerance to ethanol-induced dopamine release in the nucleus accumbens within the time course of a single acute injection. Given the strong links between dopamine and ethanol reinforcement, our findings may be relevant for understanding the time course of ethanol's reinforcing effects in vivo.