Sex differences in genetic and environmental contributions to alcohol consumption from early adolescence to young adulthood

Multi-modal neuroimaging reveals differences in alcohol-cue reactivity but not neurometabolite concentrations in adolescents who drink alcohol

BACKGROUND

The objective of this multi-modal neuroimaging study was to identify neuroscience-informed treatment targets for adolescent alcohol use disorder (AUD) by examining potential neural alterations associated with adolescent alcohol use.

METHODS

Adolescents (ages 17-19) who heavily used (n=49) or did not use alcohol (n=22) were recruited for a multi-modal neuroimaging protocol, including proton magnetic resonance spectroscopy within the dorsal anterior cingulate cortex (dACC) and an fMRI alcohol cue-reactivity task. The alcohol cue-reactivity task was analyzed across 11 a priori regions-of-interest (ROI), including the dACC, and in an exploratory whole-brain approach. Correlations were run between neurometabolite levels and alcohol cue-reactivity in the dACC.

RESULTS

There were no significant group differences in absolute neurometabolite concentrations. Compared to the control group, the alcohol-using group exhibited heightened alcohol cue reactivity in the left amygdala ROI (p=0.04). The whole-brain approach identified higher alcohol cue reactivity in the alcohol-using group compared to controls in the amygdala and occipital regions, and lower reactivity in the parietal lobe. Whole-brain sex effects were noted, with females displaying higher reactivity regardless of group. No significant correlations were found between neurometabolite levels and alcohol cue-reactivity in the dACC.

CONCLUSIONS

The null neurometabolic findings may be due to age, relatively low severity of alcohol use, and non-treatment-seeking status of the participants. Females showed overall higher reactivity to alcohol cues, indicating a sex effect regardless of alcohol use history. Higher amygdala reactivity in alcohol-using adolescents suggests that emotional processing related to alcohol cues may be a useful target for future adolescent AUD interventions.

Changes over time in endorsement of 11 DSM-IV alcohol use disorder (AUD) criteria in young adults with persistent or recurrent AUD in The Collaborative Study on the Genetics of Alcoholism

BACKGROUND

Endorsement of specific Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) alcohol use disorder (AUD) criteria have been shown to change significantly over time in men in their thirties who have persistent or recurrent AUD. However, few studies have documented whether the endorsement of AUD items changes over time in younger individuals or in women. We evaluated changes in the endorsement of AUD criteria in 377 men and women with persistent or recurrent AUD during their twenties.

METHODS

Information on AUD-item endorsement over time was available for 223 men and 154 women aged 20-25 with persistent or recurrent AUD in at least three interviews in the Collaborative Study on the Genetics of Alcoholism. The statistical significance of endorsement changes over time was evaluated using the related-sample Cochran's Q test for the full sample and for men and women separately. Additional analyses evaluated sex differences in the patterns of change.

RESULTS

In the full sample, the predominant pattern was for a significant increase in the rates of endorsement for six of the seven alcohol dependence criteria but not in the four abuse criteria. A similar pattern was seen within men, but women had significant changes in only three of the seven dependence criteria.

CONCLUSIONS

Endorsement of the seven alcohol dependence criteria among individuals with persistent or recurrent AUD in their twenties generally increased, but few changes were observed in the rates of endorsement of the four abuse criteria. These results are discussed in terms of how they reflect on the nature of AUD and the DSM criteria.

Performance of the Self-Report of the Effects of Alcohol Questionnaire Across Sexes and Generations

BACKGROUND

Low level of responses (low LRs) to alcohol established using the Self-Report of the Effects of Alcohol (SRE) questionnaire are genetically influenced phenotypes related to heavy drinking and alcohol problems. To date, most studies using SREs focused on scores for the number of drinks needed for effects across the first 5 times of drinking (SRE-5), and few evaluated scores that also included the prior 3 months and heaviest drinking periods (SRE-T). This paper evaluates characteristics of SRE-5 and SRE-T within and across generations.

METHODS

Data were extracted from 407 participants across 2 generations of 107 families in the San Diego Prospective Study (SDPS). Pearson's product-moment correlations for SRE-5 and SRE-T were determined across first-degree relatives both within and across generations and sexes, as well as correlations of each measure to maximum drinking quantities and alcohol problems.

RESULTS

Responding to 4 hypotheses, first the analyses demonstrated significant within-generation positive correlations for both SRE measures across brother-brother and sister-sister pairs as well as cross-generation correlations for fathers and sons, although correlations for mothers and daughters were not robust. Second, both SRE-5 and SRE-T correlated with maximum drinks and alcohol problems for both sexes and both generations. Third, within parental and offspring generations SRE-T correlated more robustly than SRE-5 to maximum drinks and alcohol problems. Fourth, across generations SRE values for sons were more closely related to drinking quantities and problems than for their fathers, but the mother-daughter SRE relationships to adverse alcohol characteristics were not different.

CONCLUSIONS

Both the SRE-5 and SRE-T offered useful information about propensities toward heavier drinking and alcohol problems in SDPS families. Correlations with adverse alcohol outcomes were greater for the more broad-based SRE-T, but both scores appeared to be genetically influenced and continue to operate in a robust manner in both generations of these families.

Prediction of new potential associations between LncRNAs and environmental factors based on KATZ measure

The associations between genetic and environmental factors (EFs) are significant to understand the development and progression of many complex human diseases. There have been many research studies concerning genetic factors (protein-coding genes, microRNAs) and EFs but limited research addressing the associations between long noncoding RNAs (lncRNAs) and EFs. LncRNAs of more than 200 nucleotides are an important class of non-coding transcripts and are effective in the organization of gene expressions and, therefore, on the formation of diseases. Environmental factors can alter the expression patterns of some lncRNAs, so a thorough understanding of the associations between lncRNAs and environmental factors will contribute to the understanding of the mechanisms of many complex diseases at the molecular level. In this study, we have developed a model based on the KATZ measure to find potential new associations between lncRNAs and EFs by using the DLREFD database, which contains proven associations between lncRNAs and EFs. The KATZ measure and Gaussian interaction profile kernel similarity were used to predict new potential associations between lncRNAs and EFs. The AUC results obtained by global leave-one-out cross-validation and 2-fold and 5-fold cross-validations were 0.855, 0.827, 0.838, respectively. These results show that our model can predict new potential associations between lncRNAs and EFs with high reliability. Also, the results obtained in case studies demonstrate the effectiveness of our model.

A Bipartite Network and Resource Transfer-Based Approach to Infer lncRNA-Environmental Factor Associations

Phenotypes and diseases are often determined by the complex interactions between genetic factors and environmental factors (EFs). However, compared with protein-coding genes and microRNAs, there is a paucity of computational methods for understanding the associations between long non-coding RNAs (lncRNAs) and EFs. In this study, we focused on the associations between lncRNA and EFs. By using the common miRNA partners of any pair of lncRNA and EF, based on the competing endogenous RNA (ceRNA) hypothesis and the technique of resources transfer within the experimentally-supported lncRNA-miRNA and miRNA-EF association bipartite networks, we propose an algorithm for predicting new lncRNA-EF associations. Results show that, compared with another recently-proposed method, our approach is capable of predicting more credible lncRNA-EF associations. These results support the validity of our approach to predict biologically significant associations, which could lead to a better understanding of the molecular processes.

Developmental Etiologies of Alcohol Use and Their Relations to Parent and Peer Influences Over Adolescence and Young Adulthood: A Genetically Informed Approach

BACKGROUND

Distinct changes in alcohol use etiologies occur during adolescence and young adulthood. Additionally, measured environments known to influence alcohol use such as peers and parenting practice can interact or be associated with this genetic influence. However, change in genetic and environmental influences over age, as well as how associations with measured environments change over age, is understudied.

METHODS

The National Longitudinal Study of Adolescent Health (Add Health) sibling subsample was used to examine data-driven biometric models of alcohol use over ages 13 to 27. Associations between friends' drinking, parental autonomy granting, and maternal closeness were also examined.

RESULTS

The best-fitting model included a 5-factor model consisting of early (ages 13 to 20) and overall (ages 13 to 27) additive genetic and unique environmental factors, as well as 1 overall common environment factor. The overall additive genetic factor and the early unique environment factor explained the preponderance of mean differences in the alcohol use over this portion of the life span. The most important factors explaining variance attributed to alcohol use changed over age. Additionally, friend use had the strongest associations with genetic and environmental factors at all ages, while parenting practices had almost no associations at any age.

CONCLUSIONS

These results supplement previous studies indicating changes in genetic and environmental influences in alcohol use over adolescence and adulthood. However, prior research suggesting that constraining exogenous predictors of genetic and environmental factors to have effects of the same magnitude across age overlooks the differential role of factors associated with alcohol use during adolescence. Consonant with previous research, friend use appears to have a more pervasive influence on alcohol use than parental influence during this age. Interventions and prevention programs geared toward reducing alcohol use in younger populations may benefit from focus on peer influence.

Moderation of Genetic Influences on Alcohol Involvement by Rural Residency among Adolescents: Results from the 1962 National Merit Twin Study

Adolescents in rural and urban areas may experience different levels of environmental restrictions on alcohol use, with those in rural areas experiencing greater monitoring and less access to alcohol. Such restrictions may limit expression of genetic vulnerability for alcohol use, resulting in a gene-environment interaction (G × E). This phenomenon has previously been reported in Finnish and Minnesota adolescents. The current study used data from 839 same-sex twin pairs from the 1962 National Merit Scholarship Qualifying Test to determine whether the G × E interaction would be evident in this earlier time period. We also assessed whether the G × E interaction would be moderated by sex, and whether family socioeconomic status (SES; income and parental education) may mediate the G × E interaction. Findings showed the expected interaction among females, with a weaker contribution of genes (2 vs. 44%) and greater contribution of shared environment (62 vs. 29%) to variation in alcohol involvement among rural as compared to urban residents. The G × E interaction was not observed among males, and operated independently from differences in family SES among rural and urban adolescents. This study represents a partial replication in a novel setting of the moderation of the genetic contribution to alcohol use by rural/urban residency, and suggests that SES differences may not explain this effect.

Genes, Environments, and Sex Differences in Alcohol Research

OBJECTIVE

The study of sex differences has been identified as one way to enhance scientific reproducibility, and the National Institutes of Health (NIH) have implemented a new policy to encourage the explicit examination of sex differences. Our goal here is to address sex differences in behavioral genetic research on alcohol outcomes.

METHOD

We review sex differences for alcohol outcomes and whether the source and magnitude of genetic influences on alcohol consumption and alcohol use disorder (AUD) are the same across sexes; describe common research designs for studying sex-specific gene-by-environment interaction (G × E) effects; and discuss the role of statistical power and theory when testing sex-specific genetic effects.

RESULTS

There are robust sex differences for many alcohol outcomes. The weight of evidence suggests that the source and magnitude of genetic influences on alcohol consumption and AUD are the same across sexes. Whether there are sex-specific G × E effects has received less attention to date.

CONCLUSIONS

The new NIH policy necessitates a systematic approach for studying sex-specific genetic effects in alcohol research. Researchers are encouraged to report power for tests of these effects and to use theory to develop testable hypotheses, especially for studies of G × E.

Gender differences in the transmission of risk for antisocial behavior problems across generations

Previous studies have shown that children of alcohol use disorder (AUD) parents are more likely to develop alcohol problems as well as antisocial and other behavior problems. The purpose of this study was to examine gender discordance in the effect of early maternal and paternal influences on antisocial behaviors of boys and girls, as well as the environmental factors that moderate the parental effects. Specifically, we examined the effects of childhood and adulthood antisocial behavior of the parents on offspring antisocial behavior as young adults. We also examined whether mothers' and fathers' drinking problems when offspring were young children (6-8 years) affected offspring antisocial behavior as young adults (18-21 years). We evaluated 655 children from 339 families in the Michigan Longitudinal Study (MLS), a prospective study of AUD and non-AUD families. Path models were constructed in order to test for the parental contributions to offspring outcomes. We found that both mothers' and fathers' antisocial behavior contributed to the children's young adult antisocial behavior. Only mothers' drinking problems while their children were little had a significant effect on their sons' later drinking, but not on their daughters'. These different parental effects suggest that maternal and paternal influences may be mediated by different mechanisms.