Neurometabolite Levels in Alcohol Use Disorder Patients During Baclofen Treatment and Prediction of Relapse to Heavy Drinking

Alcohol-Induced Oxidative Stress and the Role of Antioxidants in Alcohol Use Disorder: A Systematic Review

Alcohol use disorder (AUD) is a highly prevalent, comorbid, and disabling disorder. The underlying mechanism of ethanol neurotoxicity and the involvement of oxidative stress is still not fully elucidated. However, ethanol metabolism has been associated with increased oxidative stress through alcohol dehydrogenase, the microsomal ethanol oxidation system, and catalase metabolic pathways. We searched the PubMed and genome-wide association studies (GWAS) catalog databases to review the literature systematically and summarized the findings focusing on AUD and alcohol abstinence in relation to oxidative stress. In addition, we reviewed the ClinicalTrials.gov resource of the US National Library of Medicine to identify all ongoing and completed clinical trials that include therapeutic interventions based on antioxidants. The retrieved clinical and preclinical studies show that oxidative stress impacts AUD through genetics, alcohol metabolism, inflammation, and neurodegeneration.

Quantifying GABA in Addiction: A Review of Proton Magnetic Resonance Spectroscopy Studies

Gamma-aminobutyric acid (GABA) signaling plays a crucial role in drug reward and the development of addiction. Historically, GABA neurochemistry in humans has been difficult to study due to methodological limitations. In recent years, proton magnetic resonance spectroscopy (¹H-MRS, MRS) has emerged as a non-invasive imaging technique that can detect and quantify human brain metabolites in vivo. Novel sequencing and spectral editing methods have since been developed to allow for quantification of GABA. This review outlines the clinical research utilization of ¹H-MRS in understanding GABA neurochemistry in addiction and summarizes current literature that reports GABA measurements by MRS in addiction. Research on alcohol, nicotine, cocaine, and cannabis addiction all suggest medications that modulate GABA signaling may be effective in reducing withdrawal, craving, and other addictive behaviors. Thus, we discuss how improvements in current MRS techniques and design can optimize GABA quantification in future studies and explore how monitoring changes to brain GABA could help identify risk factors, improve treatment efficacy, further characterize the nature of addiction, and provide crucial insights for future pharmacological development.

The Ketogenic Diet Increases In Vivo Glutathione Levels in Patients with Epilepsy

The Ketogenic Diet (KD) is a high-fat, low-carbohydrate diet that has been utilized as the first line treatment for contrasting intractable epilepsy. It is responsible for the presence of ketone bodies in blood, whose neuroprotective effect has been widely shown in recent years but remains unclear. Since glutathione (GSH) is implicated in oxidation-reduction reactions, our aim was to monitor the effects of KD on GSH brain levels by means of magnetic resonance spectroscopy (MRS). MRS was acquired from 16 KD patients and seven age-matched Healthy Controls (HC). We estimated metabolite concentrations with linear combination model (LCModel), assessing differences between KD and HC with t-test. Pearson was used to investigate GHS correlations with blood serum 3-B-Hydroxybutyrate (3HB) concentrations and with number of weekly epileptic seizures. The results have shown higher levels of brain GSH for KD patients (2.5 ± 0.5 mM) compared to HC (2.0 ± 0.5 mM). Both blood serum 3HB and number of seizures did not correlate with GSH concentration. The present study showed a significant increase in GSH in the brain of epileptic children treated with KD, reproducing for the first time in humans what was previously observed in animal studies. Our results may suggest a pivotal role of GSH in the antioxidant neuroprotective effect of KD in the human brain.

Brain GABA levels are reduced in alcoholic liver disease: A proton magnetic resonance spectroscopy study

BACKGROUND AND AIMS

Baclofen, a selective γ-aminobutyric acid (GABA)_B receptor agonist, has emerged as a potential treatment for alcohol use disorder with much unexplained variation in response to treatment efficacy and dose regimen. Several positive studies include patients with alcoholic liver disease (ALD) and/or history of heavy drinking. The aim of this paper was to examine the association of cortical GABA+ concentration with severity of liver disease (including markers of liver injury) and other clinical characteristics in alcohol patients.

METHODS

Proton magnetic resonance spectroscopy (¹ H-MRS), from the parietal lobe, was analyzed to yield absolute concentration of GABA in 24 alcohol-dependent individuals. Diagnosis of ALD, markers of liver injury, severity of liver disease (Model for End-Stage Liver Disease [MELD]), and alcohol history were assessed. Covariates included concurrent medication, age, and recent alcohol consumption.

RESULTS

Multiple linear regression revealed that GABA+ concentration was significantly predicted by MELD scores (F = 5.02, R²  = 0.59, P = 0.01; MELD: B = -0.63, P = 0.02), when controlling for covariates concurrent medication, age, and recent alcohol consumption.

CONCLUSION

Severity of ALD is associated with lower cortical concentrations of GABA+. These results may explain variations in response to the GABA_B agonist, baclofen, in the alcohol-dependent population.

Prospects for pharmacotherapies to treat alcohol use disorder: an update on recent human studies

PURPOSE OF REVIEW

The aim of this study was to provide an update on medication development efforts for alcohol use disorder (AUD) by reviewing recently published (past 2 years) human studies that evaluated medications' effects on alcohol-related outcomes.

RECENT FINDINGS

Forty-five publications were found suitable for this review. A variety of compounds have been tested in the past 2 years as potential pharmacological options for AUD, including medications that act on multiple targets (topiramate, aripiprazole, quetiapine), calcium channels (gabapentin), gamma-Aminobutyric acid receptors (baclofen, diazepam), glutamate receptors (ifenprodil, memantine, glycine), nicotinic acetylcholine receptors (varenicline, mecamylamine), α1 adrenergic receptors (prazosin, doxazosin), neuroendocrine pathways (oxytocin, a vasopressin receptor 1b antagonist, a ghrelin receptor inverse agonist) and others (samidorphan, ibudilast, N-acetylcysteine, citoline). Important findings and limitations regarding the effects of these medications on alcohol-related outcomes are discussed.

SUMMARY

There is a critical need to increase the armamentarium of medications for AUD. Human laboratory studies may help screen and prioritize promising targets and compounds before running large clinical trials. Given the complexity of AUD and the heterogeneity of afflicted patients, future studies should also investigate potential moderators and predictors of response to each pharmacological intervention.

Selecting an appropriate alcohol pharmacotherapy: review of recent findings

PURPOSE OF REVIEW

Only a few pharmacological treatments are available for treating alcohol use disorders (AUDs). Disulfiram, naltrexone and acamprosate are Food and Drug Administration (FDA)-approved and nalmefene is EMA-approved in European Union. Off-label medications, such as baclofen, gabapentin, ondansetron and topiramate are medications commonly prescribed for the treatment of AUD. The aim of this review is to give an update on recent randomized controlled trials (RCTs) and reviews evaluating pharmacological treatment for AUD.

RECENT FINDINGS

A literature search was conducted for pharmacological treatment for alcohol use disorder, published from January 2017 to January 2019. An additional search from two ongoing-study databases was performed. A total of 13 studies, 11 reviews and 7 on-going clinical trials were identified. Interest in studying baclofen as a treatment for AUD was greater compared with other medications, yet with inconclusive results. Three new RCTs of first-line medication naltrexone showed reduction in drinking.

SUMMARY

Three new published RCTs focus on baclofen and naltrexone. These results are consistent with old findings demonstrating that naltrexone reduces heavy drinking. Several RCT on baclofen do not support the use of baclofen for treatment of AUD. Encouraging results have been reported for topiramate, gabapentin and also varenicline, which might be useful in patients with comorbid nicotine dependence.

The Use of Baclofen as a Treatment for Alcohol Use Disorder: A Clinical Practice Perspective

Alcohol use disorder (AUD) is a brain disorder associated with high rates of mortality and morbidity worldwide. Baclofen, a selective gamma-aminobutyric acid-B (GABA-B) receptor agonist, has emerged as a promising drug for AUD. The use of this drug remains controversial, in part due to uncertainty regarding dosing and efficacy, alongside concerns about safety. To date there have been 15 randomized controlled trials (RCTs) investigating the use of baclofen in AUD; three using doses over 100 mg/day. Two additional RCTs have been completed but have not yet been published. Most trials used fixed dosing of 30-80 mg/day. The other approach involved titration until the desired clinical effect was achieved, or unwanted effects emerged. The maintenance dose varies widely from 30 to more than 300 mg/day. Baclofen may be particularly advantageous in those with liver disease, due to its limited hepatic metabolism and safe profile in this population. Patients should be informed that the use of baclofen for AUD is as an "off-label" prescription, that no optimal fixed dose has been established, and that existing clinical evidence on efficacy is inconsistent. Baclofen therapy requires careful medical monitoring due to safety considerations, particularly at higher doses and in those with comorbid physical and/or psychiatric conditions. Baclofen is mostly used in some European countries and Australia, and in particular, for patients who have not benefitted from the currently used and approved medications for AUD.