Effects of current smoking severity on brain gray matter volume in opioid use disorder - a voxel-based morphometry study.

Background: Cigarette smoking (CS) and opioid use disorder (OUD) significantly alter brain structure. Although OUD and cigarette smoking are highly comorbid, most prior neuroimaging research in OUD did not control for smoking severity. Specifically, the combined effect of smoking and OUD on the brain gray matter volume (GMV) remains unknown.Objectives: We used structural magnetic resonance imaging (sMRI) to examine: (1) the GMV differences between OUD and non-OUD individuals with comparable smoking severity; and (2) the differential effect of smoking severity on the brain GMV between individuals with and without OUD.Methods: We performed a secondary analysis of existing sMRI datasets of 116 individuals who smoked cigarettes daily, among whom 60 had OUD (CS-OUD; 37 male, 23 female) and 56 did not (CS; 31 male, 25 female). Brain GMV was estimated by voxel-based morphometry analysis.Results: Compared to the CS group, the CS-OUD group had a higher GMV in the occipital cortex and lower GMV in the prefrontal and temporal cortex, striatum, and pre/postcentral gyrus (whole-brain corrected-p < .05). There was a significant interaction between group and smoking severity on GMV in the medial orbitofrontal cortex (whole-brain corrected-p < .05), such that heavier smoking was associated with lower medial orbitofrontal GMV in the CS-OUD but not CS participants (r=-0.32 vs. 0.12).Conclusions: Our findings suggest a combination of independent and interactive effects of cigarette smoking and OUD on the brain gray matter. Elucidating the neuroanatomical correlates of comorbid opioid and tobacco use may shed the light on the development of novel interventions for affected individuals.

The role of withdrawal in mesocorticolimbic drug cue reactivity in opioid use disorder.

Opioid use disorder (OUD) is characterized by heightened cognitive, physiological, and neural responses to opioid-related cues that are mediated by mesocorticolimbic brain pathways. Craving and withdrawal are key symptoms of addiction that persist during physiological abstinence. The present study evaluated the relationship between the brain response to drug cues in OUD and baseline levels of craving and withdrawal. We used functional magnetic resonance imaging (fMRI) to examine brain responses to opioid-related pictures and control pictures in 29 OUD patients. Baseline measures of drug use severity, opioid craving, and withdrawal symptoms were assessed prior to cue exposure and correlated with subsequent brain responses to drug cues. Mediation analysis was conducted to test the indirect effect of drug use severity on brain cue reactivity through craving and withdrawal symptoms. We found that baseline drug use severity and opioid withdrawal symptoms, but not craving, were positively associated with the neural response to drug cues in the nucleus accumbens, orbitofrontal cortex, and amygdala. Withdrawal, but not craving, mediated the effect of drug use severity on the nucleus accumbens' response to drug cues. We did not find similar effects for the neural responses to stimuli unrelated to drugs. Our findings emphasize the central role of withdrawal symptoms as the mediator between the clinical severity of OUD and the brain correlates of sensitization to opioid-related cues. They suggest that in OUD, baseline withdrawal symptoms signal a high vulnerability to drug cues.

Extended-Release Naltrexone to Prevent Opioid Relapse in Criminal Justice Offenders.

BACKGROUND: Extended-release naltrexone, a sustained-release monthly injectable formulation of the full mu-opioid receptor antagonist, is effective for the prevention of relapse to opioid dependence. Data supporting its effectiveness in U.S. criminal justice populations are limited. METHODS: In this five-site, open-label, randomized trial, we compared a 24-week course of extended-release naltrexone (Vivitrol) with usual treatment, consisting of brief counseling and referrals for community treatment programs, for the prevention of opioid relapse among adult criminal justice offenders (i.e., persons involved in the U.S. criminal justice system) who had a history of opioid dependence and a preference for opioid-free rather than opioid maintenance treatments and who were abstinent from opioids at the time of randomization. The primary outcome was the time to an opioid-relapse event, which was defined as 10 or more days of opioid use in a 28-day period as assessed by self-report or by testing of urine samples obtained every 2 weeks; a positive or missing sample was computed as 5 days of opioid use. Post-treatment follow-up occurred at weeks 27, 52, and 78. RESULTS: A total of 153 participants were assigned to extended-release naltrexone and 155 to usual treatment. During the 24-week treatment phase, participants assigned to extended-release naltrexone had a longer median time to relapse than did those assigned to usual treatment (10.5 vs. 5.0 weeks, P<0.001; hazard ratio, 0.49; 95% confidence interval [CI], 0.36 to 0.68), a lower rate of relapse (43% vs. 64% of participants, P<0.001; odds ratio, 0.43; 95% CI, 0.28 to 0.65), and a higher rate of opioid-negative urine samples (74% vs. 56%, P<0.001; odds ratio, 2.30; 95% CI, 1.48 to 3.54). At week 78 (approximately 1 year after the end of the treatment phase), rates of opioid-negative urine samples were equal (46% in each group, P=0.91). The rates of other prespecified secondary outcome measures--self-reported cocaine, alcohol, and intravenous drug use, unsafe sex, and reincarceration--were not significantly lower with extended-release naltrexone than with usual treatment. Over the total 78 weeks observed, there were no overdose events in the extended-release naltrexone group and seven in the usual-treatment group (P=0.02). CONCLUSIONS: In this trial involving criminal justice offenders, extended-release naltrexone was associated with a rate of opioid relapse that was lower than that with usual treatment. Opioid-use prevention effects waned after treatment discontinuation. (Funded by the National Institute on Drug Abuse; ClinicalTrials.gov number, NCT00781898.).

Effects of extended-release naltrexone on the brain response to drug-related stimuli in patients with opioid use disorder.

BACKGROUND: Heightened response to drug-related cues is a hallmark of addiction. Extended-release naltrexone (XR-NTX) is a US Food and Drug Administration-approved pharmacotherapy for relapse prevention in patients with opioid use disorder (OUD). In these patients, XR-NTX has been shown to reduce brain responses to opioid-related visual stimuli. To assess the biomarker potential of this phenomenon, it is necessary to determine whether this effect is limited to opioid-related stimuli and whether it is associated with key OUD symptoms. METHODS: Using functional MRI (fMRI), we measured the brain responses to opioid-related and control (i.e., sexual and aversive) images in detoxified patients with OUD before, during and after XR-NTX treatment. Craving and withdrawal severity were evaluated using clinician- and self-administered instruments during each session. RESULTS: We included 24 patients with OUD in our analysis. During XR-NTX treatment, we found reduced responses to opioid-related stimuli in the nucleus accumbens (NAcc) and medial orbitofrontal cortex (mOFC). The reduction in mOFC response was specific to the opioid-related stimuli. The reduced NAcc and mOFC opioid cue reactivity was correlated with reduction in clinician-assessed and self-reported withdrawal symptoms, respectively. LIMITATIONS: The study was not placebo-controlled owing to ethical, safety and feasibility concerns. CONCLUSION: Extended-release naltrexone reduces the NAcc and mOFC cue reactivity in patients with OUD. This effect is specific to opioid-related stimuli in the mOFC only. The reduction in neural response to opioid-related stimuli is more robust in patients with greater decline in withdrawal severity. Our results support the clinical utility of mesocorticolimbic cue reactivity in monitoring the XR-NTX treatment outcomes and highlight the link between opioid withdrawal symptomatology and neural opioid cue reactivity.

Effects of extended-release naltrexone on the brain response to drug-related stimuli in patients with opioid use disorder.

BACKGROUND: Heightened response to drug-related cues is a hallmark of addiction. Extended-release naltrexone (XR-NTX) is a US Food and Drug Administration-approved pharmacotherapy for relapse prevention in patients with opioid use disorder (OUD). In these patients, XR-NTX has been shown to reduce brain responses to opioid-related visual stimuli. To assess the biomarker potential of this phenomenon, it is necessary to determine whether this effect is limited to opioid-related stimuli and whether it is associated with key OUD symptoms. METHODS: Using functional MRI (fMRI), we measured the brain responses to opioid-related and control (i.e., sexual and aversive) images in detoxified patients with OUD before, during and after XR-NTX treatment. Craving and withdrawal severity were evaluated using clinician- and self-administered instruments during each session. RESULTS: We included 24 patients with OUD in our analysis. During XR-NTX treatment, we found reduced responses to opioid-related stimuli in the nucleus accumbens (NAcc) and medial orbitofrontal cortex (mOFC). The reduction in mOFC response was specific to the opioid-related stimuli. The reduced NAcc and mOFC opioid cue reactivity was correlated with reduction in clinician-assessed and self-reported withdrawal symptoms, respectively. LIMITATIONS: The study was not placebo-controlled owing to ethical, safety and feasibility concerns. CONCLUSION: Extended-release naltrexone reduces the NAcc and mOFC cue reactivity in patients with OUD. This effect is specific to opioid-related stimuli in the mOFC only. The reduction in neural response to opioid-related stimuli is more robust in patients with greater decline in withdrawal severity. Our results support the clinical utility of mesocorticolimbic cue reactivity in monitoring the XR-NTX treatment outcomes and highlight the link between opioid withdrawal symptomatology and neural opioid cue reactivity.

Low Risk of Producing an Opioid Use Disorder in Primary Care by Prescribing Opioids to Prescreened Patients with Chronic Noncancer Pain.

Objective: To examine the risk of developing aberrant behaviors that might lead to a substance use disorder (addiction) when prescribing opioids for the relief of chronic noncancer pain in primary care settings. Design: Longitudinal, prospective, descriptive design with repeated measures. Setting: Private community-based internal medicine and family medicine clinics. Subjects: Patients with chronic musculoskeletal pain. Methods: Standardized measures of patient status (pain, functional impairment, psychiatric disorders, family history) and treatments provided, urine drug monitoring, and medical chart audits (presence of aberrant drug-related behaviors) were obtained in a cohort of 180 patients at the time of initiating opioids for chronic noncancer pain and at three, six, and 12 months thereafter. Results: Over the 12-month follow-up period, subjects demonstrated stable, mild to moderate levels of depression (PHQ-9 scores ranging from 9.43 to 10.92), mild anxiety (BAI scores ranging from 11.80 to 14.67), minimal aberrant drug-related behaviors as assessed by chart reviews, and a low percentage of illicit drug use as revealed by results of urine drug monitoring. Less than 5% of our study population revealed any evidence of substance use disorder. Conclusions: This prospective study suggests that patients without a recent or prior history of substance use disorder who were prescribed primarily short-acting opioids in low doses for chronic noncancer pain have a low risk for developing a substance use disorder. This finding supports the importance of prescreening patients being considered for opioid therapy and that prescription of opioids for noncancer pain may carry a lower risk of abuse in selected populations such as in private, community-based practices.

Emotional, physical and sexual abuse are associated with a heightened limbic response to cocaine cues.

Drug-reward cues trigger motivational circuitry, a response linked to drug-seeking in animals and in humans. Adverse life events have been reported to increase sensitivity to drug rewards and to bolster drug reward signaling. Therefore, we hypothesized that cocaine-dependent individuals with prior emotional, physical and sexual abuse might have a heightened mesolimbic brain response to cues for drug reward in a new brief-cue probe. Cocaine-dependent human individuals (N = 68) were stabilized in an inpatient setting and then completed an event-related blood-oxygen-level dependent functional magnetic resonance imaging task featuring 500-ms evocative (cocaine, sexual, aversive) and comparator (neutral) cues. Responses to three questions about emotional, physical and sexual abuse from the Addiction Severity Index were used to divide the patients into subgroups (history of Abuse [n = 40] versus No Abuse [n = 28]). When subjects were grouped by the historical presence or absence of emotional, physical or sexual abuse, the Abuse group showed a heightened midbrain, thalamic, caudate, and caudal orbitofrontal cortex response to cocaine cues; a similar result was found in other evocative cues, as well. These findings are the first reported for a 500-ms cocaine-cue probe, and they highlight the ability of very brief evocative cues to activate the brain's motivational circuitry. Although all participants had severe cocaine use disorders, individuals reporting prior abuse had a heightened mesolimbic response to evocative cues. To our knowledge, this is the first study in humans linking a history of abuse to a brain vulnerability (heightened mesolimbic response to drug cues) previously shown to contribute to drug-seeking.

Pharmacogenetic approaches to the treatment of alcohol addiction.

Addictive disorders are partly heritable, chronic, relapsing conditions that account for a tremendous disease burden. Currently available addiction pharmacotherapies are only moderately successful, continue to be viewed with considerable scepticism outside the scientific community and have not become widely adopted as treatments. More effective medical treatments are needed to transform addiction treatment and address currently unmet medical needs. Emerging evidence from alcoholism research suggests that no single advance can be expected to fundamentally change treatment outcomes. Rather, studies of opioid, corticotropin-releasing factor, GABA and serotonin systems suggest that incremental advances in treatment outcomes will result from an improved understanding of the genetic heterogeneity among patients with alcohol addiction, and the development of personalized treatments.

Nipping cue reactivity in the bud: baclofen prevents limbic activation elicited by subliminal drug cues.

Relapse is a widely recognized and difficult to treat feature of the addictions. Substantial evidence implicates cue-triggered activation of the mesolimbic dopamine system as an important contributing factor. Even drug cues presented outside of conscious awareness (i.e., subliminally) produce robust activation within this circuitry, indicating the sensitivity and vulnerability of the brain to potentially problematic reward signals. Because pharmacological agents that prevent these early cue-induced responses could play an important role in relapse prevention, we examined whether baclofen-a GABAB receptor agonist that reduces mesolimbic dopamine release and conditioned drug responses in laboratory animals-could inhibit mesolimbic activation elicited by subliminal cocaine cues in cocaine-dependent individuals. Twenty cocaine-dependent participants were randomized to receive baclofen (60 mg/d; 20 mg t.i.d.) or placebo. Event-related BOLD fMRI and a backward-masking paradigm were used to examine the effects of baclofen on subliminal cocaine (vs neutral) cues. Sexual and aversive cues were included to examine specificity. We observed that baclofen-treated participants displayed significantly less activation in response to subliminal cocaine (vs neutral) cues, but not sexual or aversive (vs neutral) cues, than placebo-treated participants in a large interconnected bilateral cluster spanning the ventral striatum, ventral pallidum, amygdala, midbrain, and orbitofrontal cortex (voxel threshold p < 0.005; cluster corrected at p < 0.05). These results suggest that baclofen may inhibit the earliest type of drug cue-induced motivational processing-that which occurs outside of awareness-before it evolves into a less manageable state.

Internet Gaming Disorder in the DSM-5.

The fifth revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) includes in its research appendix a potential new diagnosis-Internet gaming disorder. This article outlines the debate surrounding non-substance addictions and the rationale for including this condition in the "Conditions for Further Study" chapter in DSM-5 Section III. It also describes the diagnostic criteria that DSM-5 recommends and methods to assess Internet gaming disorder. The paper details international research related to prevalence rates, demographic, psychiatric, and neurobiological risk factors, the natural course of the condition, and promising treatment approaches. The paper concludes by describing important issues for research to address prior to official recognition of this condition as a mental disorder.

The dopamine receptor D2 (DRD2) SNP rs1076560 is associated with opioid addiction.

The risk for drug addiction is partially heritable. Genes of the dopamine system are likely candidates to harbour risk variants, as dopamine neurotransmission is involved in mediating the rewarding effects of drugs of abuse. One functional single nucleotide polymorphism in dopamine receptor D2 (DRD2), rs1076560, is involved in regulating splicing of the gene and alters the ratio of DRD2 isoforms located pre- and postsynaptically. rs1076560 has been previously associated with cocaine abuse and we set out to confirm this association in a sample of European American (EA) (n = 336) and African American (AA) (n = 1034) cocaine addicts and EA (n = 656) and AA (n = 668) controls. We also analysed the role of rs1076560 in opioid dependence by genotyping EA (n = 1041) and AA (n = 284) opioid addicts. rs1076560 was found to be nominally associated with opioid dependence in EAs (p = 0.02, OR = 1.27) and AAs (p = 0.03, OR = 1.43). When both opioid-addicted ancestral samples were combined, rs1076560 was significantly associated with increased risk for drug dependence (p = 0.0038, OR = 1.29). This association remained significant after correction for multiple testing. No association was found with cocaine dependence. These data demonstrate the importance of dopamine gene variants in the risk for opioid dependence and highlight a functional polymorphism that warrants further study.

Neural correlates of attentional bias for smoking cues: modulation by variance in the dopamine transporter gene.

Cigarette-dependent smokers automatically and involuntarily orient attention toward smoking cues (SCs). This attentional bias is clinically significant, as it may contribute to relapse. Thus, identifying neural and genetic correlates of attentional bias is critical for improving interventions. Our previous studies show that the dopamine transporter (DAT) SLC6A3 genotype exerts profound effects on limbic responses to SCs. One potential mechanism underlying these effects is greater attentional bias for SCs. Here, we explored associations between attentional bias for SCs and neural responses to SCs among 'sated' smokers genotyped for the SLC6A3 polymorphism. Pseudo-continuous arterial spin-labeled perfusion functional magnetic resonance imaging images were acquired during SC exposure in 35 smokers genotyped for the SLC6A3 variable number of tandem repeats polymorphism (n = 16, 9-repeats; n = 19, 10/10-repeats). Participants completed a visual dot-probe attentional bias task, which contained pictures of smoking and non-smoking pictures, to examine whether genetic variation in DAT influences attentional bias and to investigate relationships between attentional bias and neural responses to SCs. Although attentional bias to smoking pictures was not significantly different between 9-repeats and 10/10-repeats, 9-repeats showed a positive correlation between attentional bias and increased SC-induced brain activity in the amygdala, whereas 10/10-repeats showed an inverse correlation in the medial orbitofrontal cortex (mOFC). In group comparisons, 9-repeats exhibited positive correlations between attentional bias and SCs in the mOFC and amygdala, relative to 10/10-repeats. Findings suggest that genetic variation in the DAT gene influences brain responses associated with attentional bias; thus, providing additional support for a SC-vulnerable endophenotype.

Extended-release naltrexone modulates brain response to drug cues in abstinent heroin-dependent patients.

Drug cues play an important role in relapse to drug use. Naltrexone is an opioid antagonist that is used to prevent relapse in opioid dependence. Central opioidergic pathways may be implicated in the heightened drug cue-reactivity, but the effects of the opioid receptors' blockade on the brain responses to drug cues in opioid dependence are unknown. To pursue this question, we studied 17 abstinent i.v. heroin users with brain functional magnetic resonance imaging (fMRI) during exposure to visual heroin-related cues and matched neutral images before and 10-14 days after an injection of extended-release naltrexone (XRNTX). Whole brain analysis of variance of fMRI data showed main effect of XRNTX in the medial frontal gyrus, precentral gyrus, cuneus, precuneus, caudate and the amygdala. fMRI response was decreased in the amygdala, cuneus, caudate and the precentral gyrus and increased in the medial frontal gyrus and the precuneus. Higher plasma levels of naltrexone's major metabolite, 6-beta-naltrexol, were associated with larger reduction in the fMRI response to drug cues after XRNTX in the precentral, caudate and amygdala clusters. The present data suggest that XRNTX pharmacotherapy of opioid-dependent patients may, respectively, decrease and potentiate prefrontal and limbic cortical responses to drug cues and that this effect might be related to the XRNTX metabolism. Our findings call for further evaluation of the brain fMRI response to drug-related cues and of the 6-beta-naltrexol levels as potential biomarkers of XRNTX therapeutic effects in patients with opioid dependence.

A pilot trial of injectable, extended-release naltrexone for the treatment of co-occurring cocaine and alcohol dependence.

BACKGROUND: There is a high co-occurrence of cocaine and alcohol use disorders, and patients with both of these problems are difficult to treat. There is a reasonable rationale and some empirical data to justify a pilot trial of an injectable, extended-release formulation of naltrexone for treating co-occurring cocaine and alcohol addiction. METHODS: Eighty cocaine (n = 80) and alcohol dependent, treatment-seeking subjects were randomly assigned to receive either two monthly extended-release injections of naltrexone or two matching placebo injections in an 8-week clinical trial, with weekly medical management plus cognitive behavioral therapy visits. RESULTS: No differences in reduction in cocaine or alcohol use were observed between the injectable naltrexone and placebo groups during the 8-week trial. CONCLUSIONS: Injectable extended-release naltrexone, while an ideal method for ensuring medication adherence in these traditionally hard-to-treat patients, did not result in any measurable reduction in cocaine or alcohol use over the course of 8 weeks of treatment.

Further evidence for association of polymorphisms in the CNR1 gene with cocaine addiction: confirmation in an independent sample and meta-analysis.

Genetic research on cocaine dependence (CD) may help clarify our understanding of the disorder as well as provide insights for effective treatment. As endocannabinoid signaling and dopamine neurotransmission have been shown to be involved in drug reward, genes related to these systems are plausible candidates for susceptibility to CD. The cannabinoid receptor 1 protein regulates both the endocannabinoid and dopaminergic neurobiological systems, and polymorphisms in the cannabinoid receptor gene, CNR1, have been associated previously with substance dependence. In this study, we attempt to replicate findings associating CNR1 with CD in African Americans. Cocaine-addicted individuals (n=860) and unaffected controls (n=334) of African descent were genotyped for two single nucleotide polymorphisms (SNPs) in CNR1 (rs6454674, rs806368). We observed a significant difference in genotype frequencies between cases and controls for both SNPs (P≤0.042). A meta-analysis was also performed combining our data with that of Zuo et al. who also studied these polymorphisms in African American cocaine addicts (total n=1253 cases versus 543 controls). When our data were combined, rs6454674 increased in significance to P=0.027; however, rs806368 was no longer significant. This study confirms the association between rs6454674 and CD. However, because there is considerable co-morbidity of CD with other drugs of abuse, additional studies are necessary to determine whether polymorphisms in CNR1 induce a general susceptibility to substance dependence or are specific to cocaine addiction. Furthermore, as this population consists of American individuals of African descent, the possibility of population stratification should not be excluded.

Concurrent naltrexone and prolonged exposure therapy for patients with comorbid alcohol dependence and PTSD: a randomized clinical trial.

IMPORTANCE: Alcohol dependence comorbid with posttraumatic stress disorder (PTSD) has been found to be resistant to treatment. In addition, there is a concern that prolonged exposure therapy for PTSD may exacerbate alcohol use. OBJECTIVE: To compare the efficacy of an evidence-based treatment for alcohol dependence (naltrexone) plus an evidence-based treatment for PTSD (prolonged exposure therapy), their combination, and supportive counseling. DESIGN, SETTING, AND PARTICIPANTS: A single-blind, randomized clinical trial of 165 participants with PTSD and alcohol dependence conducted at the University of Pennsylvania and the Philadelphia Veterans Administration. Participant enrollment began on February 8, 2001, and ended on June 25, 2009. Data collection was completed on August 12, 2010. INTERVENTIONS: Participants were randomly assigned to (1) prolonged exposure therapy plus naltrexone (100 mg/d), (2) prolonged exposure therapy plus pill placebo, (3) supportive counseling plus naltrexone (100 mg/d), or (4) supportive counseling plus pill placebo. Prolonged exposure therapy was composed of 12 weekly 90-minute sessions followed by 6 biweekly sessions. All participants received supportive counseling. MAIN OUTCOMES AND MEASURES: The Timeline Follow-Back Interview and the PTSD Symptom Severity Interview were used to assess the percentage of days drinking alcohol and PTSD severity, respectively, and the Penn Alcohol Craving Scale was used to assess alcohol craving. Independent evaluations occurred prior to treatment (week 0), at posttreatment (week 24), and at 6 months after treatment discontinuation (week 52). RESULTS: Participants in all 4 treatment groups had large reductions in the percentage of days drinking (mean change, -63.9% [95% CI, -73.6% to -54.2%] for prolonged exposure therapy plus naltrexone; -63.9% [95% CI, -73.9% to -53.8%] for prolonged exposure therapy plus placebo; -69.9% [95% CI, -78.7% to -61.2%] for supportive counseling plus naltrexone; and -61.0% [95% CI, -68.9% to -53.0%] for supportive counseling plus placebo). However, those who received naltrexone had lower percentages of days drinking than those who received placebo (mean difference, 7.93%; P = .008). There was also a reduction in PTSD symptoms in all 4 groups, but the main effect of prolonged exposure therapy was not statistically significant. Six months after the end of treatment, participants in all 4 groups had increases in percentage of days drinking. However, those in the prolonged exposure therapy plus naltrexone group had the smallest increases. CONCLUSIONS AND RELEVANCE: In this study of patients with alcohol dependence and PTSD, naltrexone treatment resulted in a decrease in the percentage of days drinking. Prolonged exposure therapy was not associated with an exacerbation of alcohol use disorder. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00006489.

A multisite pilot study of extended-release injectable naltrexone treatment for previously opioid-dependent parolees and probationers.

A feasibility study was conducted to pilot test the ability of 5 sites to recruit, treat, and retain opioid-dependent offenders in a trial of extended-release injectable naltrexone (XR-NTX). The participants, 61 previously opioid-dependent individuals under legal supervision in the community, received up to 6 monthly injections of Depotrex brand naltrexone and completed a 6-month follow-up interview. Six-month outcomes showed that those who completed treatment had significantly fewer opioid-positive urines and were less likely to have been incarcerated than those who had not completed treatment. The findings indicate that XR-NTX holds promise as a feasible, effective treatment option for opioid-dependent offenders.

Dopamine transporter genotype modulation of neural responses to smoking cues: confirmation in a new cohort.

Previously we demonstrated profound effects of dopamine transporter (DAT) SLC6A3 genotype on limbic responses to smoking cues (SCs). Probands carrying at least one copy of the 9-repeat allele (9-repeat carriers) had greater neural responses to SCs in the anatomically interconnected rostral ventral striatum/medial orbitofrontal cortex (VS/mOFC), compared with homozygotes for the 10-repeat allele (10/10-repeats). To test the reliability of the initial findings, we examined perfusion functional magnetic resonance images acquired during SC exposure in a new cohort of smokers (N=26) who were genotyped for the SLC6A3 polymorphism. In smokers overall, activity was enhanced in the VS/mOFC (t=3.77). Contrasts between allelic groups revealed that 9-repeat carriers had a greater response to SCs in the VS (t=3.12) and mOFC (t=3.19). In separate groups, 9-repeat carriers showed increased activity in the VS (t=5.47) and mOFC (T=4.96), while no increases were observed in 10-repeats. Subjective reports of craving correlated with increased activity in reward-related structures including the extended amygdala, insula and post-central gyrus, and decreased activity in the dorsolateral prefrontal cortex, and were DAT-genotype dependent (r=0.63-0.96). In secondary analyses, we found that The Fagerström Test for Nicotine Dependence scores correlated with enhanced SC-induced perfusion in 10/10-repeats in the insula, mOFC, medial temporal and superior frontal gyri (r=0.50-0.82), while correlations were absent in 9-repeat carriers. Despite heterogeneity introduced by a host of factors, including variance in other genes involved in smoking behavior, we confirm that DAT genotype predicts the direction and location of neural responses to SCs.

Long-term opioid blockade and hedonic response: preliminary data from two open-label extension studies with extended-release naltrexone.

The emergence of extended-release naltrexone (XR-NTX) raises the opportunity to explore the role of endorphin blockade on hedonic response during long-term alcohol dependence treatment. A hedonic survey was administered to 74 alcohol dependent patients treated for an average of 3.5 years with nearly continuous month-long intramuscular XR-NTX. The paper-and-pencil, one-time survey asked patients about the degree of pleasure they experienced in the past 90 days with drinking alcohol, sex, exercise and other daily activities. The data revealed lower pleasure ratings for alcohol than for sex, exercise and 10 other common activities. Mean responses to drinking alcohol and gambling were significantly lower than to listening to music, sex, reading, being with friends, eating good food, eating spicy food, and playing video/card games. This effect was independent of XR-NTX dose or duration. Although this exploratory study lacked baseline data, a comparison group or control for the impact of patient discontinuation, the data indicate the feasibility of examining long-term hedonic response in recovery. The differential hedonic ratings suggest that, in patients who persist with long-term continuous therapy, XR-NTX may selectively inhibit the pleasure associated with drinking alcohol, compared to a variety of other activities.