Genetics and alcoholism: how close are we to potential clinical applications?

Subjective Effects of Alcohol Predict Alcohol Choice in Social Drinkers

INTRODUCTION

Alcohol is among the most commonly used psychoactive drugs, yet it can produce markedly different subjective effects in different people. Certain effects, including both heightened stimulatory effects and lesser sedative effects, are thought to predict repeated or excessive use. However, we do not fully understand the nature of these individual differences or their relationships to alcohol consumption. This controlled laboratory study examined subjective and physiologic responses to a moderate dose of alcohol in social drinkers in relation to the subjects' decision to consume alcohol.

METHODS

Healthy adult volunteers (N = 95) participated in a 5-session double-blind alcohol choice study. On the first 4 sessions, they received alcohol (0.8 g/kg) and placebo in alternating order, and on the fifth session, they chose and consumed whichever of the 2 they preferred. During each session, participants completed the Profile of Mood States (POMS) and Biphasic Alcohol Effects Scale (BAES) questionnaires and had their vitals recorded every 30 minutes. We compared subjective and physiologic response to alcohol during the sampling sessions in participants who chose alcohol or placebo on session 5.

RESULTS

Of the 95 participants, 55 chose alcohol (choosers) and 40 chose placebo (nonchoosers). In the full sample, alcohol produced its expected effects (e.g., increased friendliness, elation, and vigor (POMS), and stimulation and sedation (BAES)). The chooser and nonchooser groups did not differ in demographic characteristics, blood alcohol levels, or cardiovascular measures. However, the choosers experienced greater alcohol-induced increases in positive mood (POMS) and liked the drug more, whereas the nonchoosers experienced greater anger, anxiety (POMS), and sedation (BAES) after alcohol.

CONCLUSION

Both greater positive mood effects and lesser sedative effects after alcohol predicted preference under controlled conditions, suggesting that both factors can predict future consumption of alcohol.

South Korean alcohol free associations: negative expectancy not predicting drinks per occasion

INTRODUCTION AND AIMS

Cultural and biological particulars existing in East Asian countries are likely to mediate differences in the alcohol consumption experience. Despite this no research to date has directly explored the alcohol free association or expectancy of any East Asian nations. The current research aims to provide a set of South Korean alcohol expectancies.

DESIGN AND METHODS

Two hundred and thirty-seven South Koreans participated in an alcohol free association test and completed a demographic survey.

RESULTS

The results both confirmed and contradicted areas of past alcohol expectancy research. There appears to be differences in associates with high probability of recall and alcohol expectancy, where negative, negative sedating and sedating expectancy categories were not found to be predictors of South Korean drinker level.

DISCUSSION AND CONCLUSION

The results suggest that South Koreans have a more even level of negative expectancy across all drinker categories, possibly due to a combination of linguistic, cultural and biological difference found among this population. The results provide a list of South Korean alcohol free association norms for future alcohol research in the region, with the results also underlining the need for alcohol free association tests among East Asian nations.

Chronology of alcohol dependence: implications in prevention

Background:

Study of the chronology of criteria of dependence in alcohol dependence syndrome (ADS) can enable us design strategies for the prevention for ADS, which aims at reducing the occurrence of ADS.

Objective:

To study the age-wise and order-wise chronologies of ICD-10 (DCR) dependence criteria in individuals with ADS.

Materials and Methods:

Consecutively admitted and consenting inpatients with ICD-10 (DCR) diagnosis of ADS were evaluated in a structured interview after detoxification using Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA)-II.

Results:

The total sample size was 81. The mean ages at the first onset of alcohol use, development of the first criterion and International Statistical Classification of Diseases and Related Health Problems 10^th Revision (ICD-10) dependence was 18.72 years (SD, 6.84), 24.33 years (SD, 9.21) and 27.51 years (SD, 9.28), respectively. In age-wise chronology, tolerance, loss of control and craving were present in 97.53%, 80.24% and 79%, respectively, of our study sample. In order-wise chronology, either craving (16%) or tolerance (71.6%) was present as the first criterion and the presence of craving (16%), tolerance (21%) or loss of control (18.5%) was observed in the first criterion in 55.5% of the subjects.

Conclusions:

Knowledge of chronology, its frequencies and time duration between various milestones in the development of the dependence criteria may enable the selection of the target population at an early stage. The pattern of development of dependence may provide us with an opportunity for interventions to reduce the incidence of ADS, as a step toward primary prevention. Adequate training of the primary care personnel and early psychiatric referral may help in the reduction in the incidence of ADS.

Network analysis of EtOH-related candidate genes

Recently, we collected many large-scale datasets for alcohol dependence and EtOH response in five organisms and deposited them in our EtOH-related gene resource database (ERGR, http://bioinfo.mc.vanderbilt.edu/ERGR/). Based on multidimensional evidence among these datasets, we prioritized 57 EtOH-related candidate genes. To explore their biological roles, and the molecular mechanisms of EtOH response and alcohol dependence, we examined the features of these genes by the Gene Ontology (GO) term-enrichment test and network/pathway analysis. Our analysis revealed that these candidate genes were highly enriched in alcohol dependence/alcoholism and highly expressed in brain or liver tissues. All the significantly enriched GO terms were related to neurotransmitter systems or EtOH metabolic processes. Using the Ingenuity Pathway Analysis system, we found that these genes were involved in networks of neurological disease, cardiovascular disease, inflammatory response, and small molecular metabolism. Many key genes in signaling pathways were in the central position of these networks. Furthermore, our protein-protein interaction (PPI) network analysis suggested some novel candidate genes which also had evidence in the ERGR database. This study demonstrated that our candidate gene selection is effective and our network/pathway analysis is useful for uncovering the molecular mechanisms of EtOH response and alcohol dependence. This approach can be applied to study the features of candidate genes of other complex traits/phenotypes.

Conserved role of unc-79 in ethanol responses in lightweight mutant mice

The mechanisms by which ethanol and inhaled anesthetics influence the nervous system are poorly understood. Here we describe the positional cloning and characterization of a new mouse mutation isolated in an N-ethyl-N-nitrosourea (ENU) forward mutagenesis screen for animals with enhanced locomotor activity. This allele, Lightweight (Lwt), disrupts the homolog of the Caenorhabditis elegans (C. elegans) unc-79 gene. While Lwt/Lwt homozygotes are perinatal lethal, Lightweight heterozygotes are dramatically hypersensitive to acute ethanol exposure. Experiments in C. elegans demonstrate a conserved hypersensitivity to ethanol in unc-79 mutants and extend this observation to the related unc-80 mutant and nca-1;nca-2 double mutants. Lightweight heterozygotes also exhibit an altered response to the anesthetic isoflurane, reminiscent of unc-79 invertebrate mutant phenotypes. Consistent with our initial mapping results, Lightweight heterozygotes are mildly hyperactive when exposed to a novel environment and are smaller than wild-type animals. In addition, Lightweight heterozygotes exhibit increased food consumption yet have a leaner body composition. Interestingly, Lightweight heterozygotes voluntarily consume more ethanol than wild-type littermates. The acute hypersensitivity to and increased voluntary consumption of ethanol observed in Lightweight heterozygous mice in combination with the observed hypersensitivity to ethanol in C. elegans unc-79, unc-80, and nca-1;nca-2 double mutants suggests a novel conserved pathway that might influence alcohol-related behaviors in humans.

Risky alcohol use, peer and family relationships and legal involvement in adolescents with antisocial problems

The aim of the study was to examine risk and vulnerability factors contributing to problems with alcohol use in adolescence. Data relating to seven life areas (medical status, school status, social relationships, family background and relationships, psychological functioning, legal involvement, and alcohol use) was gathered using the ADAD (Adolescent Drug Abuse Diagnosis) interview. A total of 1163 Swedish adolescents (809 boys and 354 girls) between the ages of 12 and 20 years old were interviewed. All had antisocial problems and were detained at special youth homes. It was found that for those aged between 12 and 18 years, the general risk factors for alcohol use were leisure and peer problems, problems associated with family background and relationships, and criminal behavior. These results suggest that drug abuse treatment planning should focus on altering the predisposing factors that exist in these domains. It was also found that the ADAD problem areas seem to be most useful as prognostic indicators of treatment outcome for adolescents with antisocial problems who are under 18 years of age.

Confirmation of provisional quantitative trait loci for voluntary alcohol consumption: genetic analysis in chromosome substitution strains and F2 crosses derived from A/J and C57BL/6J progenitors

AIMS

Earlier research utilizing AXB/BXA recombinant inbred (RI) and AcB/BcA recombinant congenic (RC) strains of mice independently mapped provisional quantitative trait loci (QTL) for voluntary alcohol consumption (VAC) to common chromosomal regions. This study was designed to confirm QTL on chromosomes 2, 3, 5, 7, and 15 in an A/J (A)xC57Bl/6J (B6) F2 cross, and a panel of B6.A chromosome substitution strains (CSS).

METHODS AND RESULTS

AxB6F2 mice, CSS, and A/J and C57BL/6J progenitors were tested for VAC. Previously identified QTL regions were targeted for genotyping in the AxB6F2 mice. Among the AxB6F2 mice, significant differences in VAC were associated with loci on chromosome 2 (peak marker D2Mit367) and chromosome 3 (D3Mit189). Additionally, a significant interaction was observed between loci on chromosome 15 (D15Mit245) and chromosome 2 (D2Mit367). A survey of the CSS panel provided further evidence for VAC QTLs on chromosomes 2 and 15. In the CSS panel, lower ethanol consumption was observed in those strains carrying the A/J 2 or 15 chromosome on a B6 background. This finding is consistent with the allelic influences observed in AxB6F2 mice in this study and those reported previously in the RI and RC strains of mice. Specifically, A/J alleles were associated with decreased ethanol consumption whereas C57BL/6J alleles were associated with increased ethanol consumption.

CONCLUSION

The present results confirm previously reported QTL, on chromosomes 2 and 15 for VAC in RI and RC strains. Collectively, the regions on chromosomes 2 and 15 have now been replicated in at least three independent crosses derived from the A/J and C57BL/6J progenitors. The identification of potential candidate genes for the chromosome 15 QTL is discussed in the context of an in-silico analysis.

Mice selectively bred for high- or low-alcohol-induced locomotion exhibit differences in dopamine neuron function

Elevated sensitivity to the euphoric or stimulant effects of ethanol is associated with higher levels of alcohol use in some human populations. Midbrain dopamine neurons are thought to be important mediators of both ethanol reward and locomotor stimulation. Patch-clamp recordings were used to examine the electrical properties of dopamine neurons in a genetic model of heightened (FAST) and reduced (SLOW) sensitivity to the locomotor-activating effects of ethanol. Pacemaker firing of dopamine neurons was faster in FAST than SLOW mice, as was the current density through I(H) channels. Acute administration of ethanol accelerated the firing of dopamine neurons to a greater extent in recordings from FAST than SLOW mice. Dopamine neurons from FAST mice also exhibited reduced GABA(A) receptor-mediated synaptic input, compared with SLOW mice. The results suggest that dopamine neuron I(H) channels, firing rate, and GABAergic input may play a role in sensitivity to the locomotor activation observed at early time points after ethanol administration and could underlie differences in sensitivity to alcohol relevant to risk for alcohol abuse.