Biological mechanisms in alcohol dependence--new perspectives

Internet addiction and mental health disorders in high school students in a Peruvian region: a cross-sectional study

OBJECTIVES

To determine the association between internet addiction disorder (IAD) and anxiety and depressive symptomatology in high school students in two private schools in Chiclayo, Peru, during the COVID-19 pandemic.

MATERIALS AND METHODS

Analytical cross-sectional investigation of 505 adolescents from two private schools. The dependent variables were anxiety and depressive symptomatology, measured with the Beck Adapted Depression Questionnaire (BDI-IIA) and the Beck Anxiety Inventory (BAI), respectively. The main independent variable was IAD, measured with the Internet Addiction Test instrument(IATI). Prevalence ratios (PR) and 95% confidence intervals (95%CI) were estimated.

RESULTS

The average age was 14.16 years and 54.9% were women. 22.2% and 3.2% presented mild and moderate IAD; respectively. 9.3% presented severe anxiety and 34.3% severe depressive symptomatology. In the simple regression, adolescents with mild, moderate and severe IAD presented 19% (PR = 1.19; 95%CI: 1.05-1.35), 25% (PR = 1.25; 95%CI: 1.02-1.53) and 53% (PR = 1.47; 95% CI: 1.47-1.60) higher prevalence of depressive symptomatology; however, this association was not maintained in the multiple model. Anxiety increased 196% in adolescents with severe IAD (PR = 2.96; 95%CI: 1.86-4.71).

CONCLUSION

 We found that 2, 1, and 3 out of 10 students presented IAD, depressive symptomatology, and anxiety, respectively. We did not find an association between IAD and depressive symptomatology, but we did find an association with anxiety. Among the factors associated with the development of depressive symptomatology were the male sex, the presence of eating disorders, subclinical insomnia, using devices for more than 2 h, and using the Internet for academic activities. About anxiety, the associated factors are the female sex, the presence of eating disorders, subclinical insomnia, and the use of the Internet as social interaction. We recommend implementing counseling programs in view of the imminent introduction of the Internet as a pillar in education.

Combining Metabolomics and Interpretable Machine Learning to Reveal Plasma Metabolic Profiling and Biological Correlates of Alcohol-Dependent Inpatients: What About Tryptophan Metabolism Regulation?

Alcohol dependence (AD) is a condition of alcohol use disorder in which the drinkers frequently develop emotional symptoms associated with a continuous alcohol intake. AD characterized by metabolic disturbances can be quantitatively analyzed by metabolomics to identify the alterations in metabolic pathways. This study aimed to: i) compare the plasma metabolic profiling between healthy and AD-diagnosed individuals to reveal the altered metabolic profiles in AD, and ii) identify potential biological correlates of alcohol-dependent inpatients based on metabolomics and interpretable machine learning. Plasma samples were obtained from healthy (n = 42) and AD-diagnosed individuals (n = 43). The plasma metabolic differences between them were investigated using liquid chromatography-tandem mass spectrometry (AB SCIEX^® QTRAP 4500 system) in different electrospray ionization modes with scheduled multiple reaction monitoring scans. In total, 59 and 52 compounds were semi-quantitatively measured in positive and negative ionization modes, respectively. In addition, 39 metabolites were identified as important variables to contribute to the classifications using an orthogonal partial least squares-discriminant analysis (OPLS-DA) (VIP > 1) and also significantly different between healthy and AD-diagnosed individuals using univariate analysis (p-value < 0.05 and false discovery rate < 0.05). Among the identified metabolites, indole-3-carboxylic acid, quinolinic acid, hydroxy-tryptophan, and serotonin were involved in the tryptophan metabolism along the indole, kynurenine, and serotonin pathways. Metabolic pathway analysis revealed significant changes or imbalances in alanine, aspartate, glutamate metabolism, which was possibly the main altered pathway related to AD. Tryptophan metabolism interactively influenced other metabolic pathways, such as nicotinate and nicotinamide metabolism. Furthermore, among the OPLS-DA-identified metabolites, normetanephrine and ascorbic acid were demonstrated as suitable biological correlates of AD inpatients from our model using an interpretable, supervised decision tree classifier algorithm. These findings indicate that the discriminatory metabolic profiles between healthy and AD-diagnosed individuals may benefit researchers in illustrating the underlying molecular mechanisms of AD. This study also highlights the approach of combining metabolomics and interpretable machine learning as a valuable tool to uncover potential biological correlates. Future studies should focus on the global analysis of the possible roles of these differential metabolites and disordered metabolic pathways in the pathophysiology of AD.

[Mindfulness in Development-oriented Approaches to Substance Use Prevention and Therapy: Rationale, Design and Objectives of the Research Consortium IMAC-Mind]

Mindfulness in Development-oriented Approaches to Substance Use Prevention and Therapy: Rationale, Design and Objectives of the Research Consortium IMAC-Mind Substance use disorders (SUD) are a major contributor to morbidity and mortality. They are typically initiated during adolescence and can have fatal implications for healthy development. Despite substantial scientific advances, there remains a need to prioritize research directed at reducing risks for SUD, particularly in vulnerable periods and populations from a developmental perspective. Research indicates that reward sensitivity, impulsivity, deficient self-regulation, and stress reactivity develop markedly in childhood and adolescence and play an important role in the initiation and maintenance of SUD. A growing number of research results suggest that these factors can be favorably influenced by mindfulness-based interventions and that mindfulness-based exercises can be successfully integrated into established prevention and treatment programs. In this paper we summarize the conceptual relationships between the development and maintenance of addiction disorders and mindfulness, discuss existing empirical findings with regard to childhood and adolescence, and present the aims, study designs and intervention models of the subprojects from the ongoing research network "IMAC-Mind: Improving Mental Health and Reducing Addiction in Childhood and Adolescence through Mindfulness: Mechanisms, Prevention and Treatment".

Alcohol Withdrawal and Proopiomelanocortin Neuropeptides in an Animal Model of Alcohol Dependence

BACKGROUND

Alcohol is one of the leading threats to health worldwide. Craving for alcohol makes abstinence a difficult challenge by maintaining alcohol dependence. Many studies suppose the hypothalamic-pituitary-adrenal axis, especially the proopiomelanocortin (POMC)-derived neuropeptides, to mediate craving during withdrawal in alcohol dependence. Evidence is available that the two POMC proteins, α-melanocyte-stimulating hormone (α-MSH) and β-endorphin (β-END) are altered by alcohol consumption and influence alcohol consumption, respectively.

OBJECTIVES

We investigated the dynamics of α-MSH and β-END during alcohol withdrawal and the influence of intraperitoneal administration of either α-MSH or β-END in an established rodent model (Wistar rats) for alcohol dependence.

RESULTS

After long-term alcohol self-administration over 12 months and repeated deprivation periods for 3 days, we found a significant decrease in α-MSH levels during withdrawal in rodents (p = 0.006) compared to controls, while β-END levels remained unchanged. Treatment with intraperitoneally administered α-MSH and β-END did not affect alcohol drinking behavior after deprivation.

CONCLUSION

We demonstrate the effects of alcohol deprivation on α-MSH in alcohol-dependent rodents, which appear to mimic α-MSH alteration found after fasting periods during appetite regulation. Therefore, low α-MSH levels are a possible indicator for craving in alcohol-dependent individuals and hence would be a potential target for anti-craving treatment.

Desacylghrelin but not acylghrelin is reduced during smoking cessation

This study focused on the acetylation status of ghrelin examining acyl- and desacylghrelin and its effect on craving during 14 days of smoking abstinence. This is the first study demonstrating changes in desacylghrelin plasma levels in smokers compared to non-smokers while there was no difference of acylated ghrelin. Future studies should specifically refer to plasma ghrelin as either desacyl- or acylghrelin since both have different effects on tobacco-seeking behavior and the underlying physiology.

The importance of nutrition in aiding recovery from substance use disorders: A review

BACKGROUND

Nutrition is a prerequisite for health; yet, there is no special nutritional assessment or guidance for drug and alcohol dependent individuals, despite the fact that their food consumption is often very limited, risking malnutrition. Further, the premise is examined that malnutrition may promote drug seeking and impede recovery from substance use disorders (SUD).

METHOD

A narrative review addressed the relationship between substance use disorders and nutrition, including evidence for malnutrition, as well as their impact on metabolism and appetite regulation. The implications of the biopsychology of addiction and appetite for understanding the role of nutrition in SUD were also considered.

RESULTS

The literature overwhelmingly finds that subjects with alcohol use disorder (AUD) and drug use disorder (DUD) typically suffer from nutrient deficiencies. These nutrient deficiencies may be complicit in the alcoholic myopathy, osteopenia and osteoporosis, and mood disorders including anxiety and depression, observed in AUD and DUD. These same individuals have also been found to have altered body composition and altered hormonal metabolic regulators. Additionally, brain processes fundamental for survival are stimulated both by food, particularly sweet foods, and by substances of abuse, with evidence supporting confusion (addiction transfer) when recovering from SUD between cravings for a substance and craving for food.

CONCLUSION

Poor nutritional status in AUD and DUD severely impacts their physical and psychological health, which may impede their ability to resist substances of abuse and recover their health. This review contributes to a better understanding of interventions that could best support individuals with substance use disorders.

Alcohol use disorders

Alcohol use disorders are common in developed countries, where alcohol is cheap, readily available, and heavily promoted. Common, mild disorders often remit in young adulthood, but more severe disorders can become chronic and need long-term medical and psychological management. Doctors are uniquely placed to opportunistically assess and manage alcohol use disorders, but in practice diagnosis and treatment are often delayed. Brief behavioural intervention is effective in primary care for hazardous drinkers and individuals with mild disorders. Brief interventions could also encourage early entry to treatment for people with more-severe illness who are underdiagnosed and undertreated. Sustained abstinence is the optimum outcome for severe disorder. The stigma that discourages treatment seeking needs to be reduced, and pragmatic approaches adopted for patients who initially reject abstinence as a goal. To engage people in one or more psychological and pharmacological treatments of equivalent effectiveness is more important than to advocate a specific treatment. A key research priority is to improve the diagnosis and treatment of most affected people who have comorbid mental and other drug use disorders.

SWI/SNF chromatin remodeling regulates alcohol response behaviors in Caenorhabditis elegans and is associated with alcohol dependence in humans

Alcohol abuse is a widespread and serious problem. Understanding the factors that influence the likelihood of abuse is important for the development of effective therapies. There are both genetic and environmental influences on the development of abuse, but it has been difficult to identify specific liability factors, in part because of both the complex genetic architecture of liability and the influences of environmental stimuli on the expression of that genetic liability. Epigenetic modification of gene expression can underlie both genetic and environmentally sensitive variation in expression, and epigenetic regulation has been implicated in the progression to addiction. Here, we identify a role for the switching defective/sucrose nonfermenting (SWI/SNF) chromatin-remodeling complex in regulating the behavioral response to alcohol in the nematode Caenorhabditis elegans. We found that SWI/SNF components are required in adults for the normal behavioral response to ethanol and that different SWI/SNF complexes regulate different aspects of the acute response to ethanol. We showed that the SWI/SNF subunits SWSN-9 and SWSN-7 are required in neurons and muscle for the development of acute functional tolerance to ethanol. Examination of the members of the SWI/SNF complex for association with a diagnosis of alcohol dependence in a human population identified allelic variation in a member of the SWI/SNF complex, suggesting that variation in the regulation of SWI/SNF targets may influence the propensity to develop abuse disorders. Together, these data strongly implicate the chromatin remodeling associated with SWI/SNF complex members in the behavioral responses to alcohol across phyla.

Peptide YY and ghrelin predict craving and risk for relapse in abstinent smokers

Appetite hormones are directly involved in regulating satiety, energy expenditure, and food intake, and accumulating evidence suggests their involvement in regulating reward and craving for drugs. This study investigated the ability of peptide YY (PYY) and ghrelin during the initial 24-48 h of a smoking cessation attempt to predict smoking relapse at 4 weeks. Multiple regression analysis indicated that increased PYY was associated with decreased reported craving and increased positive affect. Cox proportional hazard models showed that higher ghrelin levels predicted increased risk of smoking relapse (hazard ratio=2.06, 95% CI=1.30-3.27). These results indicate that circulating PYY may have buffering effects during the early stages of cessation while ghrelin may confer increased risk of smoking relapse. Further investigation of the links between these hormones and nicotine dependence is warranted.

Multiparameter rodent chronic model for complex evaluation of alcoholism-mediated metabolic violations

BACKGROUND

Despite of the wide spectrum of alcoholism experimental models, the majority of them are very specialized on the short list of investigated parameters and could not provide reproduction of complex metabolic changes in the rats. The aim of the present study was to estimate whether rats selected by high alcohol preference, allowed free access to 15% alcohol for 150 days, develop simultaneous multilevel disturbances of cell macromolecules structure, metabolism and oxidative/nitrosative stress.

METHODS

Wistar albino male rats were divided into groups: I - rats selected by preferences to alcohol were used for chronic alcoholism modeling by replacing water with 15% ethanol (150 days), II - control. Contents of amino acids in serum, liver mRNA CYP2E1 and CYP3A2 expression, DNA fragmentation and lipid peroxidation levels, the reduced glutathione content, superoxide dismutase, catalase, iNOS and cNOS activities were evaluated.

RESULTS

In serum of ethanol-treated rats contents of aspartic acid, serine, glycine, alanine and valine were decreased whereas contents of histidine, methionine and phenylalanine were increased. Liver CYP2E1, CYP3A2 mRNA expression, DNA fragmentation levels significantly elevated. Level of cNOS in ethanol-treated rat's hepatocytes was within the normal limits, whereas iNOS activity was raised 1.6 times. Liver pro- and anti-oxidant system alterations were shown.

CONCLUSIONS

Rats' chronic 15% alcohol consumption (150 days) led solely to complex metabolomic changes at different levels, which simultaneously characterized cell macromolecules structure, metabolism, and oxidative/nitrosative stress. Rodent model of chronic alcoholism in the proposed modification could be an adequate and reasonably priced tool for further preclinical development and testing of pharmacotherapeutic agents.

Impaired one carbon metabolism and DNA methylation in alcohol toxicity

Excessive alcohol consumption is a prominent problem and one of the major causes of mortality and morbidity around the world. Long-term, heavy alcohol consumption is associated with a number of deleterious health consequences, such as cancer, heart and liver disease, a variety of neurological, cognitive, and behavioral deficits. Alcohol consumption is also associated with developmental defects. The causes of alcohol-induced toxicity are presently unclear. One of the mechanisms underlying alcohol toxicity has to do with its interaction with folic acid/homocysteine or one-carbon metabolism (OCM). OCM is a major donor of methyl groups for methylation, particularly DNA methylation critical for epigenetic regulation of gene expression, and its disturbance may compromise DNA methylation, thereby affecting gene expression. OCM disturbance mediated by nutrient deficits is a well-known risk factor for various disorders and developmental defects (e.g., neural tube defects). In this review, we summarize the role of OCM disturbance and associated epigenetic aberrations in chronic alcohol-induced toxicity. In this review, we summarize the role of one-carbon metabolism (OCM) aberrations in chronic alcohol-induced toxicity. OCM is a major donor of methyl groups for methylation reactions, particularly DNA methylation critical for epigenetic regulation of gene expression. Alcohol interference with OCM and consequent reduced availability of methyl groups, improper DNA methylation, and aberrant gene expression can play a causative role in alcohol toxicity.

Understanding the rural-urban differences in nonmedical prescription opioid use and abuse in the United States

Nonmedical prescription opioid misuse remains a growing public problem in need of action and is concentrated in areas of US states with large rural populations such as Kentucky, West Virginia, Alaska, and Oklahoma. We developed hypotheses regarding the influence of 4 factors: (1) greater opioid prescription in rural areas, creating availability from which illegal markets can arise; (2) an out-migration of young adults; (3) greater rural social and kinship network connections, which may facilitate drug diversion and distribution; and (4) economic stressors that may create vulnerability to drug use more generally. A systematic consideration of the contexts that create differences in availability, access, and preferences is critical to understanding how drug use context varies across geography.

Molecular imaging in alcohol dependence

The cellular mechanisms of alcohol's effects in the brain are complex, targeting multiple transmitter systems. Molecular imaging has been used to study the effects of alcohol and alcohol use disorders on these various systems. Studies of dopaminergic indices have provided robust evidence for deficits in D2-mediated transmission in the striatum of chronic recently detoxified alcoholics. Their presence in the at-risk state prior to excessive drinking, and their recovery after long-term sobriety, are unclear and represent an active area of current research. Investigations of the GABAergic system have shown generalized deficits in various brain regions in the chronic abstinence phase. Studies of the opiate system have suggested alterations in some subtypes in discrete brain regions, including the ventral striatum, while studies of serotonin have been negative and those of the cannabinoid system have been inconclusive. Future investigations should target the glutamatergic system, which plays an important role both in the acute intoxicating effects of alcohol as well as in the long-term effects associated with dependence.

Alcohol and NMDA receptor: current research and future direction

The brain is one of the major targets of alcohol actions. Most of the excitatory synaptic transmission in the central nervous system is mediated by N-methyl-D-aspartate (NMDA) receptors. However, one of the most devastating effects of alcohol leads to brain shrinkage, loss of nerve cells at specific regions through a mechanism involving excitotoxicity, oxidative stress. Earlier studies have indicated that chronic exposure to ethanol both in vivo and in vitro, increases NR1 and NR2B gene expression and their polypeptide levels. The effect of alcohol and molecular changes on the regulatory process, which modulates NMDAR functions including factors altering transcription, translation, post-translational modifications, and protein expression, as well as those influencing their interactions with different regulatory proteins (downstream effectors) are incessantly increasing at the cellular level. Further, I discuss the various genetically altered mice approaches that have been used to study NMDA receptor subunits and their functional implication. In a recent countable review, epigenetic dimension (i.e., histone modification-induced chromatin remodeling and DNA methylation, in the process of alcohol related neuroadaptation) is one of the key molecular mechanisms in alcohol mediated NMDAR alteration. Here, I provide a recount on what has already been achieved, current trends and how the future research/studies of the NMDA receptor might lead to even greater engagement with many possible new insights into the neurobiology and treatment of alcoholism.

Genome-wide DNA methylation analysis in alcohol dependence

Genetic, epigenetic, and environmental factors influence the development of alcohol dependence (AD). Recent studies have shown that DNA methylation markers in peripheral blood may serve as risk markers for AD. Yet a genome-wide epigenomic approach investigating the role of DNA methylation in AD has yet to be performed. We conducted a population-based, case-control study of genome-wide DNA methylation to determine if alterations in gene-specific methylation were associated with AD in a Chinese population. Using the Illumina Infinium Human Methylation27 BeadChip, we assessed gene-specific methylation in over 27 000 CpG sites from DNA isolated from lymphocytes in 63 male AD in-patients and 65 male healthy controls. Using a multi-factorial statistical model, we observed differential methylation between cases and controls at multiple CpG sites with the majority of the methylated CpG sites being hypomethylated. Analyses with the online gene set analysis toolkit WebGestalt revealed that the genes of interest were enriched in multiple biological processes involved in AD development. Gene Ontology function annotation showed that stress, immune response and signal transduction were highly associated with AD. Further analysis by the Kyoto Encyclopedia of Genes and Genomes revealed associations with multiple pathways involved in metabolism through cytochrome P450, cytokine-cytokine receptor interaction and calcium signaling. Associations with canonical pathways previously shown to be involved in AD were also observed, such as dehydrogenases 1A (ADH1A), ADH7, aldehyde dehydrogenases 3B2 (ALDH3B2) and cytochrome P450 2A13. We present evidence that alterations in DNA methylation may be associated with AD, which is consistent with epigenetic theory.

The genetics of alcohol dependence: advancing towards systems-based approaches

BACKGROUND

Personalized treatment for psychopathologies, in particular alcoholism, is highly dependent upon our ability to identify patterns of genetic and environmental effects that influence a person's risk. Unfortunately, array-based whole genome investigations into heritable factors that explain why one person becomes dependent upon alcohol and another does not, have indicated that alcohol's genetic architecture is highly complex. That said, uncovering and interpreting the missing heritability in alcohol genetics research has become all the more important, especially since the problem may extend to our inability to model the cumulative and combinatorial relationships between common and rare genetic variants. As numerous studies begin to illustrate the dependency of alcohol pharmacotherapies on an individual's genotype, the field is further challenged to identify new ways to transcend agnostic genomewide association approaches. We discuss insights from genetic studies of alcohol related diseases, as well as issues surrounding alcohol's genetic complexity and etiological heterogeneity. Finally, we describe the need for innovative systems-based approaches (systems genetics) that can provide additional statistical power that can enhance future gene-finding strategies and help to identify heretofore-unrealized mechanisms that may provide new targets for prevention/treatments efforts. Emerging evidence from early studies suggest that systems genetics has the potential to organize our neurological, pharmacological, and genetic understanding of alcohol dependence into a biologically plausible framework that represents how perturbations across evolutionarily robust biological systems determine susceptibility to alcohol dependence.

Variation in regulator of G-protein signaling 17 gene (RGS17) is associated with multiple substance dependence diagnoses

Background

RGS17 and RGS20 encode two members of the regulator of G-protein signaling RGS-Rz subfamily. Variation in these genes may alter their transcription and thereby influence the function of G protein-coupled receptors, including opioid receptors, and modify risk for substance dependence.

Methods

The association of 13 RGS17 and eight RGS20 tag single nucleotide polymorphisms (SNPs) was examined with four substance dependence diagnoses (alcohol (AD), cocaine (CD), opioid (OD) or marijuana (MjD)] in 1,905 African Americans (AAs: 1,562 cases and 343 controls) and 1,332 European Americans (EAs: 981 cases and 351 controls). Analyses were performed using both χ² tests and logistic regression analyses that covaried sex, age, and ancestry proportion. Correlation of genotypes and mRNA expression levels was assessed by linear regression analyses.

Results

Seven RGS17 SNPs showed a significant association with at least one of the four dependence traits after a permutation-based correction for multiple testing (0.003≤P_empirical≤0.037). The G allele of SNP rs596359, in the RGS17 promoter region, was associated with AD, CD, OD, or MjD in both populations (0.005≤P_empirical≤0.019). This allele was also associated with significantly lower mRNA expression levels of RGS17 in YRI subjects (P = 0.002) and non-significantly lower mRNA expression levels of RGS17 in CEU subjects (P = 0.185). No RGS20 SNPs were associated with any of the four dependence traits in either population.

Conclusions

This study demonstrated that variation in RGS17 was associated with risk for substance dependence diagnoses in both AA and EA populations.