Effects of pharmacological and genetic regulation of COMT activity in alcohol use disorder: a randomized, placebo-controlled trial of tolcapone.

Alcohol Use Disorder (AUD) is characterized by loss of control over drinking. Behavioral control is mediated, in part, by cortical dopamine signaling. Inhibition of catechol-O-methyltransferase (COMT), the enzyme primarily responsible for cortical dopamine inactivation, may increase cortical dopamine, especially among individuals with genetically mediated lower dopaminergic tone, such as COMT rs4680 (val158met) val-allele homozygotes. This study was a randomized, placebo-controlled, pharmacogenetic trial of the COMT inhibitor tolcapone. Ninety non-treatment-seeking AUD individuals were prospectively genotyped for rs4680 and randomized to tolcapone (200 mg t.i.d.) or placebo for 8 days. At baseline and on day 7, peripheral COMT activity was assayed, and participants completed an fMRI alcohol cue-reactivity task; on day 8, they completed a bar-lab paradigm. Primary outcomes were: (1) natural drinking during the medication period; (2) alcohol self-administration in the bar lab; and (3) alcohol cue-elicited cortical (right inferior frontal gyrus [rIFG]) and ventral striatal activation. At baseline, the rs4680 val-allele had an additive effect on COMT activity. Tolcapone, relative to placebo, reduced COMT activity in all genotype groups. COMT genotype moderated tolcapone's effect on drinking during the medication period and in the bar lab, such that tolcapone, relative to placebo, reduced drinking only among val-allele homozygotes. Tolcapone did not affect cue-elicited ventral striatal activation but reduced rIFG activation; less rIFG activation on day 7 was associated with less drinking during the medication period. Taken together, these data suggest that COMT inhibition may reduce drinking specifically among individuals genetically predisposed to excessive COMT activity and potentially low cortical dopamine tone.ClinicalTrials.gov identifier: NCT02949934 https://clinicaltrials.gov/ct2/show/NCT02949934.

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.

Dopaminergic Genetic Variation Influences Aripiprazole Effects on Alcohol Self-Administration and the Neural Response to Alcohol Cues in a Randomized Trial.

Dopamine (DA) signaling regulates many aspects of Alcohol Use Disorder (AUD). However, clinical studies of dopaminergic medications, including the DA partial agonist aripiprazole (APZ), have been inconsistent, suggesting the possibility of a pharmacogenetic interaction. This study examined whether variation in DA-related genes moderated APZ effects on reward-related AUD phenotypes. The interacting effects of APZ and a variable number tandem repeat (VNTR) polymorphism in DAT1/SLC6A3 (the gene encoding the DA transporter (DAT)) were tested. In addition, interactions between APZ and a genetic composite comprising the DAT1 VNTR and functional polymorphisms in catechol-O-methyltransferase (COMT), DRD2, and DRD4 were evaluated. Ninety-four non-treatment-seeking individuals with AUD were genotyped for these polymorphisms, randomized to APZ (titrated to 15 mg) or placebo for 8 days, and underwent an fMRI alcohol cue-reactivity task (day 7; n=81) and a bar lab paradigm (day 8). Primary outcomes were alcohol cue-elicited ventral striatal (VS) activation and the number of drinks consumed in the bar lab. DAT1 genotype significantly moderated medication effects, such that APZ, relative to placebo, reduced VS activation and bar-lab drinking only among carriers of the DAT1 9-repeat allele, previously associated with lower DAT expression and greater reward-related brain activation. The genetic composite further moderated medication effects, such that APZ reduced the primary outcomes more among individuals who carried a larger number of DAT1, COMT, DRD2, and DRD4 alleles associated with higher DA tone. Taken together, these data suggest that APZ may be a promising AUD treatment for individuals with a genetic predisposition to higher synaptic DA tone.

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.

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.

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.

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.

Sertraline and cognitive behavioral therapy for depressed alcoholics: results of a placebo-controlled trial.

Alcoholism and depression are common disorders that frequently co-occur in the same individual. Selective serotonin reuptake inhibitors (SSRIs) are effective in the treatment of depression and also had decreased drinking in some studies of heavy drinkers and alcoholics. The reported effect of serotonergic medications on alcohol intake in depressed alcoholics has not been consistent. Most previous studies have not investigated the use of an SSRI in the context of cognitive behavioral therapy (CBT), a known efficacious treatment of both alcoholism and depression. The study presented here was a randomized placebo-controlled 12-week trial of sertraline combined with individual CBT focused on both alcoholism relapse prevention and depressive symptoms. Subjects were 82 currently depressed, actively drinking alcohol-dependent individuals. Subjects had either primary (independent) major depression (70 subjects) or substance-induced mood disorder and at least 1 first-degree relative (parent, sibling, or child) with an affective disorder (12 subjects). Depression and alcohol consumption outcomes were measured weekly over 12 weeks. Sertraline was well tolerated and all subjects had decreases in both depression and alcohol use during the study compared with baseline. Subjects who received sertraline had fewer drinks per drinking day than subjects who received placebo, but other drinking outcomes were not different between the 2 treatment groups. Treatment with sertraline was associated with less depression at the end of treatment in female subjects compared with female subjects who received placebo. Less drinking during the study was associated with improved depression outcome. The findings in this study suggest that sertraline, compared with placebo, may provide some modest benefit in terms of drinking outcome and also may lead to improved depression in female alcohol-dependent subjects. Additionally, alcohol relapse prevention CBT, delivered according to manual guidelines with modifications that provide specific attention to depression, appeared to be of benefit to subjects, although this interpretation is limited by the design of the study.