Predictors of Naltrexone Response in a Randomized Trial: Reward-Related Brain Activation, OPRM1 Genotype, and Smoking Status.

This corrects the article DOI: 10.1038/npp.2017.74.

Predictors of Naltrexone Response in a Randomized Trial: Reward-Related Brain Activation, OPRM1 Genotype, and Smoking Status.

Naltrexone reduces drinking among individuals with alcohol use disorders (AUDs), but it is not effective for everyone. Variability in its effects on reward-related brain activation, genetic variation, and/or cigarette smoking may account for this mixed response profile. This randomized clinical trial tested the effects of naltrexone on drinking and alcohol cue-elicited brain activation, evaluated whether OPRM1 A118G genotype or smoking moderated these effects, and explored whether the effects of medication on cue-elicited activation predicted subsequent drinking. One hundred and fifty-two treatment-seeking individuals with alcohol dependence, half preselected to carry at least one A118G G (Asp) allele, were randomized to naltrexone (50 mg) or placebo for 16 weeks and administered an fMRI alcohol cue reactivity task at baseline and after 2 weeks of treatment. Naltrexone, relative to placebo, significantly reduced alcohol cue-elicited activation of the right ventral striatum (VS) between baseline and week 2 and reduced heavy drinking over 16 weeks. OPRM1 genotype did not significantly moderate these effects, but G-allele carriers who received naltrexone had an accelerated return to heavy drinking after medication was stopped. Smoking moderated the effects of medication on drinking, such that naltrexone was superior to placebo only among smokers. The degree of reduction in right VS activation between scans interacted with medication in predicting subsequent drinking, such that individuals with greater reduction in activation who received naltrexone, but not placebo, experienced the least heavy drinking during the following 14 weeks. These data replicate previous findings that naltrexone reduces heavy drinking and reward-related brain activation among treatment-seeking individuals with AUDs, and indicate that smoking and the magnitude of reduction in cue-elicited brain activation may predict treatment response.

Randomized Controlled Trial Comparing Exercise to Health Education for Stimulant Use Disorder: Results From the CTN-0037 STimulant Reduction Intervention Using Dosed Exercise (STRIDE) Study.

OBJECTIVE: To evaluate exercise as a treatment for stimulant use disorders. METHODS: The STimulant Reduction Intervention using Dosed Exercise (STRIDE) study was a randomized clinical trial conducted in 9 residential addiction treatment programs across the United States from July 2010 to February 2013. Of 497 adults referred to the study, 302 met all eligibility criteria, including DSM-IV criteria for stimulant abuse and/or dependence, and were randomized to either a dosed exercise intervention (Exercise) or a health education intervention (Health Education) control, both augmenting treatment as usual and conducted thrice weekly for 12 weeks. The primary outcome of percent stimulant abstinent days during study weeks 4 to 12 was estimated using a novel algorithm adjustment incorporating self-reported Timeline Followback (TLFB) stimulant use and urine drug screen (UDS) data. RESULTS: Mean percent of abstinent days based on TLFB was 90.8% (SD = 16.4%) for Exercise and 91.6% (SD = 14.7%) for Health Education participants. Percent of abstinent days using the eliminate contradiction (ELCON) algorithm was 75.6% (SD = 27.4%) for Exercise and 77.3% (SD = 25.1%) for Health Education. The primary intent-to-treat analysis, using a mixed model controlling for site and the ELCON algorithm, produced no treatment effect (P = .60). In post hoc analyses controlling for treatment adherence and baseline stimulant use, Exercise participants had a 4.8% higher abstinence rate (78.7%) compared to Health Education participants (73.9%) (P = .03, number needed to treat = 7.2). CONCLUSIONS: The primary analysis indicated no significant difference between exercise and health education. Adjustment for intervention adherence showed modestly but significantly higher percent of abstinent days in the exercise group, suggesting that exercise may improve outcomes for stimulant users who have better adherence to an exercise dose. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01141608.

Regional Brain Activity in Abstinent Methamphetamine Dependent Males Following Cue Exposure.

BACKGROUND: Neuroimaging of drug-associated cue presentations has aided in understanding the neurobiological substrates of craving and relapse for cocaine, alcohol, and nicotine. However, imaging of cue-reactivity in methamphetamine addiction has been much less studied. METHOD: Nine caucasian male methamphetamine-dependent subjects and nine healthy controls were scanned in a Phillips 3.0T MRI scan when they viewed a randomized presentation of visual cues of methamphetamine, neutral objects, and rest conditions. Functional Imaging data were analyzed with Statistical Parametric Mapping software 5 (SPM 5). RESULTS: Methamphetamine subjects had significant brain activation in the ventral striatum and medial frontal cortex in comparison to meth pictures and neutral pictures in healthy controls (p<0.005, threshold 15 voxels). Interestingly the ventral striatum activation significantly correlated with the days since the last use of meth (r=-0.76, p=0.017). No significant activity was found in healthy control group. CONCLUSION: The preliminary data suggest that methamphetamine dependent subjects, when exposed to methamphetamine-associated visual cues, have increased brain activity in ventral striatum, caudate nucleus and medial frontal cortex which subserve craving, drug-seeking, and drug use.

Suicide-specific Safety in the Inpatient Psychiatric Unit.

In total, 75% of suicides reported to the Joint Commission as sentinel events since 1995, have occurred in psychiatric settings. Ensuring patient safety is one of the primary tasks of inpatient psychiatric units. A review of inpatient suicide-specific safety components, inclusive of incidence and risk; guidelines for evidence-based care; environmental safety; suicide risk assessment; milieu observation and monitoring; psychotherapeutic interventions; and documentation is provided. The Veterans Health Administration (VA) has been recognized as an exemplar system in suicide prevention. A VA inpatient psychiatric unit is used to illustrate the operationalization of a culture of suicide-specific safety. We conclude by describing preliminary unit outcomes and acknowledging limitations of suicide-specific inpatient care and gaps in the current inpatient practices and research on psychotherapeutic interventions, observation, and monitoring.

Extended release naltrexone for alcohol use disorders: quasi-experimental effects on mortality and subsequent detoxification episodes.

BACKGROUND: Utilization of extended release naltrexone (XRN) for alcohol use disorders (AUDs) in the U.S. Veterans Health Administration (VHA) has been limited, perhaps due to high cost, lack of established superiority over less expensive alternatives including oral naltrexone, and related formulary restrictions. Despite these barriers, pockets of higher utilization exist in VHA, allowing for the quasi-experimental examination of the effects of XRN on 1-year mortality and number of subsequent detoxification episodes among patients with high rates of psychiatric comorbidities and previous psychosocial and pharmacological addiction treatment. METHODS: Using propensity score-weighted mixed-effects logistic regression, 1-year mortality was compared between patients with AUDs who received XRN in fiscal year 2010 (n = 387) and a random sample of patients with AUDs who did not receive XRN (n = 3,759). Among the subgroup of patients who had at least 1 detoxification episode in the previous year, 1-year mortality and number of subsequent detoxification episodes were compared between those who did and did not receive XRN. RESULTS: Overall, 1-year mortality for the patients receiving XRN was significantly lower than for the comparison group who did not receive XRN (odds ratio [OR] = 0.30; p < 0.001). Among patients with a detoxification episode in the previous year, those receiving XRN had, on average, 0.80 fewer subsequent detoxification episodes (p < 0.001) and significantly lower mortality (OR = 0.78, p < 0.001) in the postindex year. CONCLUSIONS: Among patients with AUDs, those receiving XRN had lower 1-year mortality and fewer detoxifications compared to similar patients not receiving XRN. These results, although observational, support the use of XRN, especially among patients with high rates of psychiatric comorbidities and previous addiction treatment who are still struggling with AUDs and/or facing a period of vulnerability to relapse.

Variation in SLC1A1 is related to combat-related posttraumatic stress disorder.

Candidate gene studies have yet to investigate the glutamate system, the primary excitatory neurotransmitter of the HPA-axis related to PTSD risk. We investigated 13 SNPs in the glutamate transporter gene (SLC1A1) in relation to PTSD among combat-exposed veterans. Participants (n=418) completed a diagnostic interview and provided a blood sample for DNA isolation and genotyping. A subset of participants (n=391) had severity and combat exposure data available. In the primary logistic regression gender and rs10739062 were significant predictors of PTSD diagnosis (OR=0.50; OR=1.43). In the linear regression analysis, combat exposure was the only significant predictor (ß=0.16) of severity. A computed genetic risk sum score was significant in relation to PTSD diagnosis (OR=1.15) and severity scores (ß=0.14) above and beyond the effects of combat exposure. This study provides preliminary support for the relationship of glutamate transporter polymorphisms to PTSD risk and the need for further genetic studies within this system.

The relationship between years of cocaine use and brain activation to cocaine and response inhibition cues.

AIMS: Functional magnetic resonance imaging research has attempted to elucidate the neurobehavioral underpinnings of cocaine dependence by evaluating differences in brain activation to cocaine and response inhibition cues between cocaine-dependent individuals and controls. This study investigated associations between task-related brain activation and cocaine use characteristics. DESIGN: Cross-sectional. SETTING: The Center for Biomedical Imaging at the Medical University of South Carolina, USA. PARTICIPANTS: Fifty-one cocaine users (41 dependent). MEASUREMENTS: Brain activation to cocaine-cue exposure and Go No-Go tasks in six a priori selected brain regions of interest and cocaine use characteristics (i.e. cocaine dependence status, years of cocaine use, cocaine use in the past 90 days) assessed via standardized interviews. FINDINGS: Participants demonstrated elevated activation to cocaine (bilateral ventral striatum, dorsal caudate, amygdala) and response inhibition (bilateral anterior cingulate, insula, inferior frontal gyrus) cues in all hypothesized brain regions. Years of cocaine use was associated with task-related brain activation, with more years of cocaine use associated with greater activation to cocaine cues in right (F = 7.97, P = 0.01) and left (F = 5.47, P = 0.02) ventral striatum and greater activation to response inhibition cues in left insula (F = 5.10, P = 0.03) and inferior frontal gyrus (F = 4.12, P = 0.05) controlling for age, cocaine dependence status and cocaine use in the past 90 days. CONCLUSIONS: Years of cocaine use may be more centrally related to cocaine cue and response inhibition brain activation than cocaine dependence diagnosis or amount of recent use.

Varenicline effects on drinking, craving and neural reward processing among non-treatment-seeking alcohol-dependent individuals.

RATIONALE: The α4ß2 nicotinic acetylcholine receptor partial agonist varenicline has been reported to reduce drinking among both heavy-drinking smokers and primary alcoholics, and this effect may be related to varenicline-mediated reduction of alcohol craving. Among smokers, varenicline has been reported to modulate cigarette cue-elicited brain activation in several reward-related areas. OBJECTIVES: This pilot study tested varenicline's effects on drinking, alcohol craving, and alcohol cue-elicited activation of reward-related brain areas among non-treatment-seeking alcohol-dependent individuals. METHODS: Thirty-five such individuals (mean age = 30, 57 % male, 76 % heavy drinking days in the past month, 15 smokers) were randomized to either varenicline (titrated to 2 mg) or placebo for 14 days, and were administered an alcohol cue reactivity fMRI task on day 14. A priori regions of interest (ROIs) were bilateral and medial orbitofrontal cortex (OFC), right ventral striatum (VS), and medial prefrontal cortex (mPFC). RESULTS: Despite good medication adherence, varenicline did not reduce heavy drinking days or other drinking parameters. It did, however, increase self-reported control over alcohol-related thoughts and reduced cue-elicited activation bilaterally in the OFC, but not in other brain areas. CONCLUSIONS: These data indicate that varenicline reduces alcohol craving and some of the neural substrates of alcohol cue reactivity. However, varenicline effects on drinking mediated by cue-elicited brain activation and craving might be best observed among treatment-seekers motivated to reduce their alcohol consumption.

Brain activation to cocaine cues and motivation/treatment status.

Motivation to change is believed to be a key factor in therapeutic success in substance use disorders; however, the neurobiological mechanisms through which motivation to change impacts decreased substance use remain unclear. Existing research is conflicting, with some investigations supporting decreased and others reporting increased frontal activation to drug cues in individuals seeking treatment for substance use disorders. The present study investigated the relationship between motivation to change cocaine use and cue-elicited brain activity in cocaine-dependent individuals using two conceptualizations of 'motivation to change': (1) current treatment status (i.e. currently receiving versus not receiving outpatient treatment for cocaine dependence) and (2) self-reported motivation to change substance use, using the Stages of Change Readiness and Treatment Eagerness Scale. Thirty-eight cocaine-dependent individuals (14 currently in treatment) completed a diagnostic assessment and an fMRI cocaine cue-reactivity task. Whole-brain analyses demonstrated that both treatment-seeking and motivated participants had lower activation to cocaine cues in a wide variety of brain regions in the frontal, occipital, temporal and cingulate cortices relative to non-treatment-seeking and less motivated participants. Future research is needed to explain the mechanism by which treatment and/or motivation impacts neural cue reactivity, as such work could potentially aid in the development of more effective therapeutic techniques for substance-dependent patients.

Prospective associations between brain activation to cocaine and no-go cues and cocaine relapse.

BACKGROUND: The ability to predict potential for relapse to substance use following treatment could be very useful in targeting aftercare strategies. Recently, a number of investigators have focused on using neural activity measured by fMRI to predict relapse propensity. The purpose of the present study was to use fMRI to investigate prospective associations between brain reactivity to cocaine and response inhibition cues and relapse to cocaine use. METHODS: Thirty cocaine-dependent participants with clean cocaine urine drug screens (UDS) completed a baseline fMRI scan, including a cocaine-cue reactivity task and a go no-go response inhibition task. After participating in a brief clinical trial of d-cycloserine for the facilitation of cocaine-cue extinction, they returned for a one-week follow-up UDS. Associations between baseline activation to cocaine and inhibition cues and relapse to cocaine use were explored. RESULTS: Positive cocaine UDS was significantly associated with cocaine-cue activation in the right putamen and insula, as well as bilateral occipital regions. Associations between positive cocaine UDS and activation to no-go cues were concentrated in the postcentral gyri, a region involved in response execution. CONCLUSIONS: Although preliminary, these results suggest that brain imaging may be a useful tool for predicting risk for relapse in cocaine-dependent individuals. Further, larger-scale naturalistic studies are needed to corroborate and extend these findings.

Impact of DCS-facilitated cue exposure therapy on brain activation to cocaine cues in cocaine dependence.

BACKGROUND: The development of addiction is marked by a pathological associative learning process that imbues incentive salience to stimuli associated with drug use. Recent efforts to treat addiction have targeted this learning process using cue exposure therapy augmented with d-cycloserine (DCS), a glutamatergic agent hypothesized to enhance extinction learning. To better understand the impact of DCS-facilitated extinction on neural reactivity to drug cues, the present study reports fMRI findings from a randomized, double-blind, placebo-controlled trial of DCS-facilitated cue exposure for cocaine dependence. METHODS: Twenty-five participants completed two MRI sessions (before and after intervention), with a cocaine-cue reactivity fMRI task. The intervention consisted of 50mg of DCS or placebo, combined with two sessions of cocaine cue exposure and skills training. RESULTS: Participants demonstrated cocaine cue activation in a variety of brain regions at baseline. From the pre- to post-study scan, participants experienced decreased activation to cues in a number of regions (e.g., accumbens, caudate, frontal poles). Unexpectedly, placebo participants experienced decreases in activation to cues in the left angular and middle temporal gyri and the lateral occipital cortex, while DCS participants did not. CONCLUSIONS: Three trials of DCS-facilitated cue exposure therapy for cocaine dependence have found that DCS either increases or does not significantly impact response to cocaine cues. The present study adds to this literature by demonstrating that DCS may prevent extinction to cocaine cues in temporal and occipital brain regions. Although consistent with past research, results from the present study should be considered preliminary until replicated in larger samples.

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.

Functional neuroimaging studies of alcohol cue reactivity: a quantitative meta-analysis and systematic review.

A comprehensive understanding of the neurobiology of alcohol cue reactivity is critical in identifying the neuropathology of alcohol use disorders (AUD) and developing treatments that may attenuate alcohol craving and reduce relapse risk. Functional neuroimaging studies have identified many brain areas in which alcohol cues elicit activation. However, extant studies have included relatively small numbers of cases, with AUD of varying severity, and have employed many different cue paradigms. We used activation likelihood estimation, a quantitative, coordinate-based meta-analytic method, to analyze the brain areas activated by alcohol-related cues across studies, and to examine whether these areas were differentially activated between cases and controls. Secondarily, we reviewed correlations between behavioral measures and cue-elicited activation, as well as treatment effects on such activation. Data analyzed were from 28 studies of 679 cases and 174 controls. Among cases, alcohol cues elicited robust activation of limbic and prefrontal regions, including ventral striatum, anterior cingulate and ventromedial prefrontal cortex. As compared to controls, cases demonstrated greater activation of parietal and temporal regions, including posterior cingulate, precuneus and superior temporal gyrus. Cue-elicited activation of ventral striatum was most frequently correlated with behavioral measures and most frequently reduced by treatment, but these results were often derived from region-of-interest analyses that interrogated only limbic regions. These findings support long-standing theories of mesolimbic involvement in alcohol cue processing, but suggest that cue-elicited activation of other brain areas may more clearly differentiate cases from controls. Prevention and treatment for AUD should consider interventions that may reduce cue-elicited activation of these areas.

Computer simulation games as an adjunct for treatment in male veterans with alcohol use disorder.

This study examined the impact of a computer simulation designed to provide the opportunity for individuals with alcohol use disorders (AUDs) to practice relapse prevention skills. Participants were 41 male veterans enrolled in an intensive outpatient substance abuse treatment program. Participants were randomly assigned to either view educational slides about treatment for AUD or play a simulation videogame for eight sessions within 12 weeks. Participants were assessed at a 4-week follow-up visit. Outcome measures included relapse rates as well as ratings on the Obsessive Compulsive Drinking Scale (OCDS) and a custom-designed relapse prevention self efficacy scale. While rates of relapse did not differ between groups, those who played the game showed overall reductions in ratings on the OCDS, as well as higher ratings of self-efficacy at week 8, suggesting that the videogame simulation may be a useful adjunct to AUD treatment.

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.

Health service utilization before and after evidence-based treatment for PTSD.

Posttraumatic stress disorder (PTSD) is associated with functional impairment, co-occurring diagnoses, and increased health care utilization. Associated high demand for health care services is an important contributor to the large public-health cost of PTSD. Treatments incorporating exposure therapy are efficacious in ameliorating or eliminating PTSD symptoms. Accordingly, the Veterans Health Administration has made significant investments toward nationwide dissemination of a manualized exposure therapy protocol, prolonged exposure (PE). PE is effective with veterans; however, the relationship between PE and mental health service utilization is unknown. The current study investigates PE as it relates to actual tracked mental health service utilization in an urban VA medical center. A sample of 60 veterans with a diagnosis of PTSD was used to examine mental health service utilization in the 12-months prior to and 12-months after being offered PE. Hierarchical Linear Models and traditional repeated-measures ANOVA were used to estimate R²- and d-type effect sizes for service utilization. Associated estimated cost saving are reported. PE was associated with large reductions in symptoms and diagnosis remission. Treatment was also associated with statistically significant, large reductions in mental health service utilization for veterans who completed treatment. Findings suggest that expanding access to PE can increase access to mental health services in general by decreasing ongoing demand for specialty care clinical services.

A pilot trial of neuropsychological evaluations conducted via telemedicine in the Veterans Health Administration.

INTRODUCTION: Many veterans live in rural areas distant from Veterans Affairs Medical Centers (VAMCs) and receive primary medical care from community-based outpatient clinics (CBOCs). These veterans often must travel great distances to the nearest VAMC for neuropsychological evaluations, resulting in poor access to care, travel reimbursement costs, fee-basis evaluations of uncontrolled quality, and driving safety concerns. Return trips for feedback compound complications. Accordingly, we initiated a pilot trial of neuropsychological evaluation and feedback via telemedicine (i.e., clinical videoconferencing). SUBJECTS AND METHODS: Participants were veterans referred for neuropsychological evaluation from a rural CBOC 115 miles from the regional VAMC. All veterans were given the choice to undergo evaluation at the CBOC via telemedicine or in-person at the VAMC. Telemedicine equipment allowed presentation of digitized material with simultaneous patient observation. Testing materials were organized in numbered folders and given to veterans by CBOC clerks immediately prior to evaluation. Clerks returned completed materials via facsimile. RESULTS: Fifteen veterans from the rural CBOC were seen for neuropsychological evaluation. Eight chose telemedicine evaluation. Groups based on evaluation modality appeared similar on demographics, referral basis, resulting neuropsychiatric diagnoses, and follow-through on recommendations. No significant technical or clinical difficulties were encountered, and veterans reported satisfaction with telemedicine. All veterans requested feedback via telemedicine. CONCLUSIONS: Neuropsychological evaluation via telemedicine is feasible and appears comparable to in-person evaluation. Experiences are encouraging and consistent with the broader literature on the acceptance of and satisfaction with clinical videoconferencing. Future studies will assess possible psychometric issues in clinical populations.

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.

Effects of divalproex on smoking cue reactivity and cessation outcomes among smokers achieving initial abstinence.

Divalproex, a GABA agonist, may be a useful agent in the treatment of tobacco dependence. Cue reactivity assessment paradigms are ideally suited to explore basic mechanisms underlying the pharmacological effects of medications that purport to have efficacy for smoking cessation. Our primary goal in the current study was to examine the effects of divalproex on in-treatment reactivity to smoking-relevant and affective cues, and to determine if these reactions were predictive of posttreatment smoking behavior. There were 120 nicotine dependent smokers enrolled in an 8-week double-blind clinical trial and randomly assigned to either divalproex or placebo conditions. Of these, 72 smokers (60% female) who achieved a minimal level of abstinence underwent an in-treatment cue reactivity assessment. Contrary to expectations, divalproex was associated with greater craving and arousal during smoking cue presentation. Divalproex also inhibited cardiovascular response to pleasant cues. Although no significant differences in cessation-related outcomes between divalproex- and placebo-treated participants were observed, cue-elicited craving to smoke predicted end-of-treatment and posttreatment smoking rates. These findings suggest that in-treatment cue reactivity assessment may proactively and dynamically inform ongoing treatment as well as provide a tool for screening potential medications for smoking cessation.