Clinically relevant genetic biomarkers from the brain in alcoholism with representation on high resolution chromosome ideograms

Integrative genomics approach identifies glial transcriptomic dysregulation and risk in the cortex of individuals with Alcohol Use Disorder

BACKGROUND

Alcohol use disorder (AUD) is a prevalent neuropsychiatric disorder that is a major global health concern, affecting millions of people worldwide. Past studies of AUD used underpowered single cell analysis or bulk homogenates of postmortem brain tissue, which obscures gene expression changes in specific cell types. Therefore, we sought to conduct the largest-to-date single-nuclei RNAseq (snRNA-seq) postmortem brain study in AUD to elucidate transcriptomic pathology with cell type-specific resolution.

METHODS

Here we performed snRNA-seq and high dimensional network analysis of 73 post-mortem samples from individuals with AUD (N=36, Nnuclei= 248,873) and neurotypical controls (N=37, Nnuclei= 210,573) in the dorsolateral prefrontal cortex from both male and female donors. Additionally, we performed analysis for cell type-specific enrichment of aggregate genetic risk for AUD as well as integration of the AUD proteome for secondary validation.

RESULTS

We identified 32 distinct cell clusters and found widespread cell type-specific transcriptomic changes across the cortex in AUD, particularly affecting glial populations. We found the greatest dysregulation in novel microglial and astrocytic subtypes that accounted for the majority of differential gene expression and co-expression modules linked to AUD. Differential gene expression was secondarily validated by integration of a publicly available AUD proteome. Finally, analysis for aggregate genetic risk for AUD identified subtypes of glia as potential key players not only affected by but causally linked to the progression of AUD.

CONCLUSIONS

These results highlight the importance of cell type-specific molecular changes in AUD and offer opportunities to identify novel targets for treatment on the single-nuclei level.

Integrative genomics approach identifies glial transcriptomic dysregulation and risk in the cortex of individuals with Alcohol Use Disorder

Alcohol use disorder (AUD) is a prevalent neuropsychiatric disorder that is a major global health concern, affecting millions of people worldwide. Past molecular studies of AUD used underpowered single cell analysis or bulk homogenates of postmortem brain tissue, which obscures gene expression changes in specific cell types. Here we performed single nuclei RNA-sequencing analysis of 73 post-mortem samples from individuals with AUD (N=36, N nuclei = 248,873) and neurotypical controls (N=37, N nuclei = 210,573) in both sexes across two institutional sites. We identified 32 clusters and found widespread cell type-specific transcriptomic changes across the cortex in AUD, particularly affecting glia. We found the greatest dysregulation in novel microglial and astrocytic subtypes that accounted for the majority of differential gene expression and co-expression modules linked to AUD. Analysis for cell type-specific enrichment of aggregate genetic risk for AUD identified subtypes of microglia and astrocytes as potential key players not only affected by but causally linked to the progression of AUD. These results highlight the importance of cell-type specific molecular changes in AUD and offer opportunities to identify novel targets for treatment.

Chromatin-mediated alternative splicing regulates cocaine-reward behavior

Neuronal alternative splicing is a key gene regulatory mechanism in the brain. However, the spliceosome machinery is insufficient to fully specify splicing complexity. In considering the role of the epigenome in activity-dependent alternative splicing, we and others find the histone modification H3K36me3 to be a putative splicing regulator. In this study, we found that mouse cocaine self-administration caused widespread differential alternative splicing, concomitant with the enrichment of H3K36me3 at differentially spliced junctions. Importantly, only targeted epigenetic editing can distinguish between a direct role of H3K36me3 in splicing and an indirect role via regulation of splice factor expression elsewhere on the genome. We targeted Srsf11, which was both alternatively spliced and H3K36me3 enriched in the brain following cocaine self-administration. Epigenetic editing of H3K36me3 at Srsf11 was sufficient to drive its alternative splicing and enhanced cocaine self-administration, establishing the direct causal relevance of H3K36me3 to alternative splicing of Srsf11 and to reward behavior.

Morphopathological approaches in alcoholism

Alcohol morphopathology has been studied over time, being a central interest of specialists, due to the negative consequences it has on the brain and the entire central nervous system (CNS). This paper is a review of the literature that emphasizes one of the problems of the modern world, that of the compulsive consume of alcohol, having a great global spread. The studies analyzed are topical, being carried out in recent years and consider the harmful effects of alcohol on brain formations, such as corpus callosum, gray and white matter, hippocampus, and hypothalamus. At the same time, alcohol is a risk factor for cardiovascular diseases, and in combination with other harmful substances, increases the risk of various diseases, such as neurodegeneration. Abusive alcohol consumption can bring epigenetic changes and alter the typical functioning of cognitive functions. This paper focuses on alcohol consumption on adolescents and young people, which is a serious problem nowadays. Alcohol also influences the way of behavioral expression, becoming a risk for the development of mental disorders. However, alcohol withdrawal is another problem with different effects and must be in the attention of specialists.

Bibliometric Insights in Genetic Factors of Substance-Related Disorders: Intellectual Developments, Turning Points, and Emerging Trends

Substance-related disorders are a group of medical conditions that affect a person's brain and behavior and lead to an inability to control the use of legal or illegal drug(s) or medication. Substance-related disorder is a serious public health and society problem worldwide. Genetic factors have been proven to have an important role. Researchers have carried out a lot of work in this field, and a large number of research results have been published in academic journals around the world. However, there are few overviews of research progress, presentation, and development trends in this field. In this study, a total of 636 articles related to genetic factors of substance-related disorders were retrieved from the Web of Science (WoS) database from 1997 to 2018, and the scientific literatures were analyzed by bibliometrics. The study found that the United States (US) has maintained a leading position in the field of research, with many core institutions and plenty of high-quality research results. Alcohol use disorder is still the most concerning issue in this field. Over the past 20 years, new techniques such as genome-wide association study (GWAS) based on high-throughput sequencing technology have replaced family studies, twin studies, and retrospective studies in this field. We believe that it is urgent to study the genetic factors of substance-related disorders, which can greatly deepen the understanding of the pathogenesis of substance-related disorders and may provide potential targets for precise treatment of such diseases.

Medication-enhanced behavior therapy for alcohol use disorder: Naltrexone, Alcoholics Anonymous Facilitation, and OPRM1 genetic variation

Medication-assisted behavior treatment for alcohol use disorder (AUD) holds promise to enhance the efficacy of medication and of behavior therapy when administered individually. The present study examines the treatment benefit of combined outpatient naltrexone (NTX) treatment with Alcoholics Anonymous Facilitation (AAF) behavior therapy, in the context of OPRM1 genotype. The minor OPRM1 Asp40 G-allele has been associated with greater positive reinforcing effects of alcohol consumption and greater alcohol craving, suggesting that individuals carrying the OPRM1 G allele may have an improved naltrexone response. Twenty patients, including 7 G-allele carriers, received 90 days of naltrexone with medication support and dispensing sessions, and ten AAF behavior therapy sessions. During treatment and the eight-week posttreatment follow-up, an overall increase in percent days abstinent was observed for the sample as a whole, but G-allele carriers reported relatively heavier drinking relative to other subjects. These findings suggest that this enhanced medication-assisted behavior treatment is a promising therapeutic combination, and mirror other recent findings that G-allele carriers may require more intensive treatment.

The genetic epidemiology of substance use disorder: A review

BACKGROUND

Substance use disorder (SUD) remains a significant public health issue. A greater understanding of how genes and environment interact to regulate phenotypes comprising SUD will facilitate directed treatments and prevention.

METHODS

The literature studying the neurobiological correlates of SUD with a focus on the genetic and environmental influences underlying these mechanisms was reviewed. Results from twin/family, human genetic association, gene-environment interaction, epigenetic literature, phenome-wide association studies are summarized for alcohol, nicotine, cannabinoids, cocaine, and opioids.

RESULTS

There are substantial genetic influences on SUD that are expected to influence multiple neurotransmission pathways, and these influences are particularly important within the dopaminergic system. Genetic influences involved in other aspects of SUD etiology including drug processing and metabolism are also identified. Studies of gene-environment interaction emphasize the importance of environmental context in SUD. Epigenetic studies indicate drug-specific changes in gene expression as well as differences in gene expression related to the use of multiple substances. Further, gene expression is expected to differ by stage of SUD such as substance initiation versus chronic substance use. While a substantial literature has developed for alcohol and nicotine use disorders, there is comparatively less information for other commonly abused substances.

CONCLUSIONS

A better understanding of genetically-mediated mechanisms involved in the neurobiology of SUD provides increased opportunity to develop behavioral and biologically based treatment and prevention of SUD.

White matter disruptions in male cocaine polysubstance users: Associations with severity of drug use and duration of abstinence

BACKGROUND

Cocaine dependence has been associated with alterations in the brain's white matter integrity, yet relevant questions remain about what alterations are linked to cocaine use and/or polysubstance use, and whether they are amenable to abstinence.

METHODS

This study applied a single measurement session of diffusion tensor imaging (DTI) to examine white matter structure in male cocaine polysubstance users (n=37) versus male healthy controls (n=38), along with correlations between DTI measures and patterns of polysubstance use and duration of abstinence. Specifically, we conducted voxel-wise analyses of fractional anisotropy (FA) in the corpus callosum, frontolimbic, striatal and cingulate tracts relevant to drug sequelae.

RESULTS

Cocaine polysubstance users, compared to controls, showed lower FA in the body of the corpus callosum, anterior cingulate, uncinate fasciculus and retrolenticular part of the internal capsule. Duration of cocaine use had a marginal negative association with FA in the corpus callosum, and duration of alcohol use was negatively associated with FA in the internal capsule and the uncinate fasciculus. Duration of cocaine abstinence was positively correlated with FA in the uncinate fasciculus, posterior cingulate and fornix-striatum. In the context of cocaine polysubstance use, chronicity of cocaine use is therefore likely to be associated with lower FA in the corpus callosum, and chronicity of alcohol use with lower FA in the frontal-striatal and frontal-limbic tracts. Longer abstinence was correlated to greater FA in frontal-striatal and frontal-limbic tracts, though the direction of causality remains unclear.

CONCLUSION

Since the results did not survive multiple comparison-corrected thresholds, more studies are needed to confirm these indications.

A Genetic Animal Model of Alcoholism for Screening Medications to Treat Addiction

The purpose of this review is to present up-to-date pharmacological, genetic, and behavioral findings from the alcohol-preferring P rat and summarize similar past work. Behaviorally, the focus will be on how the P rat meets criteria put forth for a valid animal model of alcoholism with a highlight on its use as an animal model of polysubstance abuse, including alcohol, nicotine, and psychostimulants. Pharmacologically and genetically, the focus will be on the neurotransmitter and neuropeptide systems that have received the most attention: cholinergic, dopaminergic, GABAergic, glutamatergic, serotonergic, noradrenergic, corticotrophin releasing hormone, opioid, and neuropeptide Y. Herein, we sought to place the P rat's behavioral and neurochemical phenotypes, and to some extent its genotype, in the context of the clinical literature. After reviewing the findings thus far, this chapter discusses future directions for expanding the use of this genetic animal model of alcoholism to identify molecular targets for treating drug addiction in general.

GABBR1 and SLC6A1, Two Genes Involved in Modulation of GABA Synaptic Transmission, Influence Risk for Alcoholism: Results from Three Ethnically Diverse Populations

BACKGROUND

Animal and human studies indicate that GABBR1, encoding the GABAB1 receptor subunit, and SLC6A1, encoding the neuronal gamma-aminobutyric acid (GABA) transporter GAT1, play a role in addiction by modulating synaptic GABA. Therefore, variants in these genes might predict risk/resilience for alcoholism.

METHODS

This study included 3 populations that differed by ethnicity and alcoholism phenotype: African American (AA) men: 401 treatment-seeking inpatients with single/comorbid diagnoses of alcohol and drug dependence, 193 controls; Finnish Caucasian men: 159 incarcerated alcoholics, half with comorbid antisocial personality disorder, 181 controls; and a community sample of Plains Indian (PI) men and women: 239 alcoholics, 178 controls. Seven GABBR1 tag single nucleotide polymorphisms were genotyped in the AA and Finnish samples; rs29220 was genotyped in the PI for replication. Also, a uniquely African, functional SLC6A1 insertion promoter polymorphism (IND) was genotyped in the AAs.

RESULTS

We found a significant and congruent association between GABBR1 rs29220 and alcoholism in all 3 populations. The major genotype (heterozygotes in AAs, Finns) and the major allele in PIs were significantly more common in alcoholics. Moreover, SLC6A1 IND was more abundant in controls, that is, the major genotype predicted alcoholism. An analysis of combined GABBR1 rs29220 and SLC6A1 IND genotypes showed that rs29220 heterozygotes, irrespective of their IND status, had an increased risk for alcoholism, whereas carriers of the IND allele and either rs29220 homozygote were more resilient.

CONCLUSIONS

Our results show that with both GABBR1 and SLC6A1, the minor genotypes/alleles were protective against risk for alcoholism. Finally, GABBR1 rs29220 might predict treatment response/adverse effects for baclofen, a GABAB receptor agonist.

[Genius between music and disease: Medical considerations on Ludwig van Beethoven]

Ludwig van Beethoven is nowadays considered to be one of the greatest composers in the history of music and his myth-like reputation is enhanced by his deafness; however, deafness was not the only condition which affected his genius. Due to the many lamentations contained in his letters about continuously recurring health problems, various attempts at an interpretation of Beethoven's personality have been undertaken. These included psychoanalytical considerations with respect to his father-mother relationship and also diagnostic attempts with reference to the symptoms of a possible borderline personality syndrome. The aim of this article is to comprehensively analyze the diseases of the patient Beethoven from the perspective of specialized medical disciplines based on new research results, to summarize various discipline-specific considerations and to make a contemporary assessment from the viewpoint of current scientific results.