Review: Environmental influences on alcohol use: Informing research on the joint effects of genes and the environment in diverse U.S. populations

Understanding alcohol use and alcohol use disorders from a developmental psychopathology perspective: Research advances, challenges, and future directions

As part of the special issue of Development and Psychopathology honoring the remarkable contributions of Dr Dante Cicchetti, the current paper attempts to describe the recent contributions that a developmental psychopathology perspective has made in understanding the development of alcohol use and alcohol-related problems over the lifespan. The paper also identifies some of the future challenges and research directions. Because the scope of this task far exceeds the confines of a journal length article this paper does not attempt a comprehensive review. Rather, it builds on an earlier review and commentary that was published in Development and Psychopathology in 2013, with a similar goal.)Building on that work and updating its conclusions and suggestions for future directions, the current paper emphasizes findings from the research areas that were identified for further study in 2013 and the findings that have been published since that time.

Community exposure to armed conflict and subsequent onset of alcohol use disorder

AIMS

To measure the independent consequences of community-level armed conflict beatings on alcohol use disorders (AUD) among males in Nepal during and after the 2000-2006 conflict.

DESIGN

A population-representative panel study from Nepal, with precise measures of community-level violent events and subsequent individual-level AUD in males. Females were not included because of low AUD prevalence.

SETTING

Chitwan, Nepal.

PARTICIPANTS

Four thousand eight hundred seventy-six males from 151 neighborhoods, systematically selected and representative of Western Chitwan. All residents aged 15-59 were eligible (response rate 93%).

MEASUREMENTS

Measures of beatings in the community during the conflict (2000-2006), including the date and distance away, were gathered through neighborhood reports, geo-location and official resources, then linked to respondents' life histories of AUD (collected in 2016-2018) using the Nepal-specific Composite International Diagnostic Interview with life history calendar. Beatings nearby predict the subsequent onset of AUD during and after the armed conflict. Data were analyzed in 2021-2022.

FINDINGS

Cohort-specific, discrete-time models revealed that within the youngest cohort (born 1992-2001), those living in neighborhoods where armed conflict beatings occurred were more likely to develop AUD compared with those in other neighborhoods (odds ratio = 1.66; 95% confidence interval = 1.02-2.71). In this cohort, a multilevel matching analysis designed to simulate a randomized trial showed the post-conflict incidence of AUD for those living in neighborhoods with any armed conflict beatings was 9.5% compared with 5.3% in the matched sample with no beatings.

CONCLUSIONS

Among male children living in Chitwan, Nepal during the 2000-2006 armed conflict, living in a neighborhood where armed conflict beatings occurred is associated with increased odds of developing subsequent alcohol use disorder. This association was independent of personal exposure to beatings and other mental disorders.

Examining interactions between polygenic scores and interpersonal trauma exposure on alcohol consumption and use disorder in an ancestrally diverse college cohort

Introduction: Genetic factors impact alcohol consumption and use disorder (AUD), with large-scale genome-wide association studies (GWAS) identifying numerous associated variants. Aggregate genetic methods in combination with important environmental factors (e.g., interpersonal trauma [IPT]) can be applied to expand our understanding of the ways by which genetic and environmental variables work together to influence alcohol consumption and disordered use. The present study aimed to detail the relationships between genome-wide polygenic scores (PGS) for alcohol phenotypes (i.e., alcohol consumption and AUD status) and IPT exposure as well as the interaction between them across ancestry. Methods: Data were drawn from the Spit for Science (S4S) study, a US college student population, where participants reported on IPT exposure prior to college and alcohol consumption and problems during college (N = 9,006; ancestry: 21.3% African [AFR], 12.5% Admixed Americas [AMR], 9.6% East Asian [EAS], 48.1% European [EUR], 8.6% South Asian [SAS]). Two trans-ancestry PGS were constructed, one for alcohol consumption and another for AUD, using large-scale GWAS summary statistics from multiple ancestries weighted using PRS-CSx. Regression models were applied to test for the presence of associations between alcohol-PGS and IPT main and interaction effects. Results: In the meta-analysis across ancestry groups, IPT exposure and PGS were significantly associated with alcohol consumption (βIPT = 0.31, P IPT = 0.0002; βPGS = 0.09, P PGS = 0.004) and AUD (ORIPT = 1.12, P IPT = 3.5 × 10-8; ORPGS = 1.02, P PGS = 0.002). No statistically significant interactions were detected between IPT and sex nor between IPT and PGS. When inspecting ancestry specific results, the alcohol consumption-PGS and AUD-PGS were only statistically significant in the EUR ancestry group (βPGS = 0.09, P PGS = 0.04; ORPGS = 1.02, P PGS = 0.022, respectively). Discussion: IPT exposure prior to college was strongly associated with alcohol outcomes in this college-age sample, which could be used as a preventative measure to identify students at high risk for problematic alcohol use. Additionally, results add to developing evidence of polygenic score association in meta-analyzed samples, highlighting the importance of continued efforts to increase ancestral representation in genetic studies and inclusive analytic approaches to increase the generalizability of results from genetic association studies.

Risk and Protective Factors Associated with Adverse Childhood Experiences in Vulnerable Families: Results of a Randomized Clinical Trial of SafeCare®

Early adversity predicts increased risk for mental and physical health problems. As such, intervention efforts, such as home-based parenting programs, have been initiated with vulnerable families to reduce adversity exposure and promote child well-being. The present randomized clinical trial had a parallel design and 1:1 allocation ratio of SafeCare augmented for an urban high-risk population (SC+) compared to standard home-based mental health services (SAU) to examine risk and protective factors proximal to child maltreatment. Parents (N=562) of young children (5 years or less) at risk of depression, intimate partner violence, or substance abuse were randomized to SC+ or SAU. A significant program effect was found in favor of SC+ for parental depression and social support, as well as within-group improvements for both groups in depression, intimate partner victimization, family resources, and social support. Promising next steps include future trials examining how improvements in parental depression and social support impact child well-being over time and further augmentation of SafeCare to enhance healthy relationships and address cultural congruency of services.

Review of Ethanol Intoxication Sensing Technologies and Techniques

The field of alcohol intoxication sensing is over 100 years old, spanning the fields of medicine, chemistry, and computer science, aiming to produce the most effective and accurate methods of quantifying intoxication levels. This review presents the development and the current state of alcohol intoxication quantifying devices and techniques, separated into six major categories: estimates, breath alcohol devices, bodily fluid testing, transdermal sensors, mathematical algorithms, and optical techniques. Each of these categories was researched by analyzing their respective performances and drawbacks. We found that the major developments in monitoring ethanol intoxication levels aim at noninvasive transdermal/optical methods for personal monitoring. Many of the "categories" of ethanol intoxication systems overlap with each other with to a varying extent, hence the division of categories is based only on the principal operation of the techniques described in this review. In summary, the gold-standard method for measuring blood ethanol levels is through gas chromatography. Early estimation methods based on mathematical equations are largely popular in forensic fields. Breath alcohol devices are the most common type of alcohol sensors on the market and are generally implemented in law enforcement. Transdermal sensors vary largely in their sensing methodologies, but they mostly follow the principle of electrical sensing or enzymatic reaction rate. Optical devices and methodologies perform well, with some cases outperforming breath alcohol devices in terms of the precision of measurement. Other estimation algorithms consider multimodal approaches and should not be considered alcohol sensing devices, but rather as prospective measurement of the intoxication influence. This review found 38 unique technologies and techniques for measuring alcohol intoxication, which is testament to the acute interest in the innovation of noninvasive technologies for assessing intoxication.

Maternal Parenting Behaviors Amplify Environmental Influences on Developmental Trajectories of Alcohol Use During Adolescence

Compared to peer alcohol use, less is known on how parenting practices may modify genetic and environmental contributions to alcohol use longitudinally across adolescence. This study examined whether two maternal parenting behaviors, supervision and harsh parenting, may suppress or amplify genetic and environmental influences on three distinct developmental trajectories of adolescent alcohol use: normative increasing, early-onset, and low trajectories. Participants were drawn from a longitudinal study of a population-based twin sample (N = 842, 84% European descent, 52.7% female). Adolescents self-reported their past year alcohol use at ages 13, 14, 15, and 17 years, and their mothers reported their supervision and harsh parenting when twins were 13, 15, and 17 years old. Maternal supervision amplified non-shared environmental influence on the normative increasing and early-onset trajectories, whereas maternal harsh parenting amplified shared environmental influence on the early-onset trajectory and non-shared environmental influence on the low trajectory, respectively. The findings suggest maternal parenting practices as a potent developmental context that modulates the environmental influences of other proximal processes on adolescent alcohol use, and suggest that family-based parenting-focused intervention could be especially beneficial for adolescents following the early-onset trajectory.

Perception of Aqueous Ethanol Binary Mixtures Containing Alcohol-Relevant Taste and Chemesthetic Stimuli

Ethanol is a complex stimulus that elicits multiple gustatory and chemesthetic sensations. Alcoholic beverages also contain other tastants that impact flavour. Here, we sought to characterize the binary interactions between ethanol and four stimuli representing the dominant orosensations elicited in alcoholic beverages: fructose (sweet), quinine (bitter), tartaric acid (sour) and aluminium sulphate (astringent). Female participants were screened for thermal taste status to determine whether the heightened orosensory responsiveness of thermal tasters (n = 21–22) compared to thermal non-tasters (n = 13–15) extends to these binary mixtures. Participants rated the intensity of five orosensations in binary solutions of ethanol (5%, 13%, 23%) and a tastant (low, medium, high). For each tastant, 3-way ANOVAs determined which factors impacted orosensory ratings. Burning/tingling increased as ethanol concentration increased in all four binary mixture types and was not impacted by the concentration of other stimuli. In contrast, bitterness increased with ethanol concentration, and decreased with increasing fructose concentration. Sourness tended to be reduced as ethanol concentration increased, although astringency intensity decreased with increasing concentration of fructose. Overall, thermal tasters tended to be more responsive than thermal non-tasters. These results provide insights into how the taste and chemesthetic profiles of alcoholic beverages across a wide range of ethanol concentrations can be manipulated by changing their composition.

Doubly Photopolymerized Holographic Sensors

Holographic sensors are two-dimensional (2D) photonic crystals that diffract narrow-band light in the visible spectrum to quantify analytes in aqueous solutions. Here, a holographic fabrication setup was developed to produce holographic sensors through a doubly polymerization system of a poly-2-hydroxyethyl methacrylate hydrogel film using a pulsed Nd:YAG laser (λ = 355 nm, 5 ns, 100 mJ). Wavelength shifts of holographic Bragg peak in response to alcohol species (0-100 vol %) were characterized. Diffraction spectra showed that the holographic sensors could be used for short-chain alcohols at concentrations up to 60 vol %. The reversibility of the sensor was demonstrated, exhibiting a response time of 7.5 min for signal saturation. After 30 cycles, the Bragg peak and color remained the same in both 20 and 60 vol %. The fabrication parameters were simulated in MATLAB using a 2D finite-difference time-domain algorithm to model the interference pattern and energy flux profile of laser beam recording in the hydrogel medium. This work demonstrates a particle-free holographic sensor that offers continuous, reversible, and rapid colorimetric readouts for the real-time quantification of alcohols.

Intersection of familial risk and environmental social control on high-risk drinking and alcohol dependence in a US national sample of adults

BACKGROUND

Effects of a family history of alcoholism may be moderated by area-level social control factors. We examine whether increased neighborhood alcohol availability (low social control environment) or increased presence of religious adherents in the county (high social control environment) interact with family history in relation to alcohol outcomes.

METHODS

Weighted data from 12,686 adult drinkers (51% male; mean age 44; 80% White, 9% Black, 11% Hispanic) in three US National Alcohol Surveys were linked with data on area-level off-premise alcohol availability and adherence to religions with strong prohibitions against drinking. Family history density had four levels (family history negative, extended family only, first-degree relative(s) only, high family density). Dichotomous outcomes were past-year high-risk drinking and alcohol dependence. Logistic regression models with interaction terms assessed whether associations of family history with alcohol outcomes differed significantly by area-level social control. Stratified models assessed differences by sex and by race/ethnicity.

RESULTS

In the full sample, effects of first-degree relatives and high family density on high-risk drinking strengthened as alcohol availability increased. This was replicated in the subsample of women and suggested in relation to dependence among men and Black drinkers. For White drinkers, higher religious social control reduced effects of first-degree relatives on high-risk drinking.

CONCLUSIONS

Low social control-in particular, greater density of off-premise alcohol outlets-appears to exacerbate effects of a family history of alcoholism on high-risk drinking. Policy makers should consider differential benefits of decreasing alcohol availability for people from high-risk families to reduce high-risk drinking and alcohol problems.

Heterogeneity of Executive Function Abilities in Recently Detoxified Patients with Alcohol Use Disorder: Evidence from a Cluster Analysis

BACKGROUND

Impairments of executive functions (EF) have been consistently reported in patients with alcohol use disorder (AUD), mostly in studies which were based on comparisons of means between groups. However, given the high heterogeneity in AUD patients, this approach could actually cover a wide range of EF patterns. In the present study, we addressed the paucity of the literature about cognitive heterogeneity in AUD by applying a cluster analytical approach on EF measures.

METHODS

Seventy-eight withdrawn AUD patients and 77 healthy Control participants completed measures targeting a variety of EF components. We then used cluster analysis to identify subgroups of AUD patients. Furthermore, the AUD subgroups were compared to the Control group to establish their specific EF patterns.

RESULTS

Findings showed that AUD patients could be divided into 3 clusters based on their EF performances. A first cluster accounting for half of the AUD sample was characterized by unimpaired EF (Cluster 1). The 2 other clusters displayed major EF deficits but differed regarding the deficient EF component. While Cluster 2 was mainly impaired on measures of rule deduction and mental flexibility, Cluster 3 was mainly characterized by a lower processing speed and impaired inhibition of an ongoing motor response. Differences in EF performances of AUD patients could be related to differences in premorbid cognitive reserve, impulsiveness patterns, and withdrawal complications.

CONCLUSIONS

This study highlights the importance of the cognitive heterogeneity in AUD by showing that AUD patients display substantially different EF patterns. Future studies should try to go beyond mere group comparisons to further deepen our understanding about cognitive differences between AUD patients. In the long run, this could lead to more personalized prevention and treatment programs specifically tailored to the patient's impairments.

Effects of Polygenic Risk and Perceived Friends' Drinking and Disruptive Behavior on Development of Alcohol Use Across Adolescence

OBJECTIVE

Developmental theory posits interacting individual and contextual factors that contribute to alcohol use across adolescence. Despite the well-documented salience of peer environmental influences on adolescent drinking, it is not known whether peer environments moderate polygenic risks for trajectories of alcohol use. The current theoretically based investigation aimed to test developmental gene-environment interaction (G×E) effects across adolescence.

METHOD

Latent growth curve models tested interactive associations of polygenic risk scores and adolescents' perceived friend drinking and disruptive behavior with adolescents' initial level of alcohol use frequency at age 16 years old and change in alcohol frequency from ages 16 to 20. The sample comprised 8,941 White adolescents (49% female) from Great Britain within the Avon Longitudinal Study of Parents and Children (ALSPAC).

RESULTS

Greater polygenic risk was associated with more frequent initial drinking as well as escalations in drinking frequency over the subsequent 5 years in latent growth curve models. Contrary to study hypotheses, no significant G×E effects were identified after controlling for confounding main and interaction effects.

CONCLUSIONS

Adolescents at heightened genetic risk may accelerate their alcohol use across adolescence, although not significantly more so in the presence of these alcohol-promoting peer environments. Future well-powered, theoretically driven replication efforts are needed to examine generalizability of these findings across diverse samples.

Effects of Polygenic Risk and Perceived Friends' Drinking and Disruptive Behavior on Development of Alcohol Use Across Adolescence

OBJECTIVE

Developmental theory posits interacting individual and contextual factors that contribute to alcohol use across adolescence. Despite the well-documented salience of peer environmental influences on adolescent drinking, it is not known whether peer environments moderate polygenic risks for trajectories of alcohol use. The current theoretically based investigation aimed to test developmental gene-environment interaction (G×E) effects across adolescence.

METHOD

Latent growth curve models tested interactive associations of polygenic risk scores and adolescents' perceived friend drinking and disruptive behavior with adolescents' initial level of alcohol use frequency at age 16 years old and change in alcohol frequency from ages 16 to 20. The sample comprised 8,941 White adolescents (49% female) from Great Britain within the Avon Longitudinal Study of Parents and Children (ALSPAC).

RESULTS

Greater polygenic risk was associated with more frequent initial drinking as well as escalations in drinking frequency over the subsequent 5 years in latent growth curve models. Contrary to study hypotheses, no significant G×E effects were identified after controlling for confounding main and interaction effects.

CONCLUSIONS

Adolescents at heightened genetic risk may accelerate their alcohol use across adolescence, although not significantly more so in the presence of these alcohol-promoting peer environments. Future well-powered, theoretically driven replication efforts are needed to examine generalizability of these findings across diverse samples.

Quantile-Specific Heritability of Intakes of Alcohol but not Other Macronutrients

Genetic heritability (h²) of alcohol use is reported to be greater in rural dwellers, distressed marriages, low socioeconomic status, in girls who are unmarried or lacking closeness with their parents or religious upbringing, in less-educated men, and in adolescents with peers using alcohol. However, these are all risk factors for heavy drinking, and the greater heritability could be due to quantile-dependent expressivity, i.e., h² dependent upon whether the phenotype (alcohol intake) is high or low relative to its distribution. Quantile regression showed that h² estimated from the offspring-parent regression slope increased significantly from lowest to highest gram/day of alcohol consumption (0.006 ± 0.001 per percent, P = 1.1 × 10^-7). Heritability at the 90th percentile of the sample distribution (0.557 ± 0.116) was 4.5-fold greater than at the 10th percentile (0.122 ± 0.037). Heritabilities for intakes of other macronutrients were not quantile-dependent. Thus quantile-dependent expressivity may explain the higher estimated heritability associated with risk factors for high alcohol consumption.

Exploring how Family and Neighborhood Stressors Influence Genetic Risk for Adolescent Conduct Problems and Alcohol Use

Previous research suggests that genetic risk factors may predispose to conduct problems and alcohol use in adolescence. Whether genetic risk factors interact with social contexts has not been well characterized among African American adolescents. Data came from a subsample of the Genes, Environment, and Neighborhood Initiative study comprising 501 African American adolescents, including 151 lifetime drinkers (56% female, mean age = 16.3, SD = 1.4). Genetic risk was assessed with polygenic risk scores for alcohol dependence. Analyses explored interactions between genetic risk and self-reported alcohol use, conduct problems, life stressors, and other covariates. The effects of two gene-environment interactions (G × E) were tested in the sample of alcohol exposed adolescents; one on conduct problems and the other on alcohol use. There were significant associations between polygenic risk for alcohol dependence and conduct problems. A significant G × E interaction showed the impact of genetic risk on conduct problems was stronger under conditions of high exposure to family and neighborhood stressors. Among this sample of African American adolescents, genetic risk for alcohol dependence was not directly associated with alcohol use but was related to more conduct problems. Further, the effect of genetic risk interacted with stressors from the family and neighborhood, so that the effect of genetic risk on conduct problems was stronger for individuals who reported greater stressors.

Recent advances in genetic studies of alcohol use disorders

PURPOSE OF REVIEW

Alcohol use disorder (AUD) is a complex genetic disorder with very high heritability. This polygenic disorder not only results in increased morbidity and mortality, it is also a substantial social and economic burden on families and the nation. For past three decades, several genetic studies were conducted to identify genes and pathways associated with AUD. This review aims to summarize past efforts and recent advances in genetic association studies of AUD and related traits.

RECENT FINDINGS

Initial genetic association studies achieved a limted success and suffered from low power due to small sample sizes. AUD is a polygenic trait and data from several thousands individuals was required to identify the genetic factors of small effect sizes. The scenario changed recently with technological advances and significant reduction in cost of the genome wide association analyses (GWAS). This enabled researchers to generate genomic data on mega biobanks and cohorts with access to extensive clinical and non-clinical phenotypes. Public access to data from biobanks and collaborative efforts of researchers lead to identification of several novel loci associated with AUDs and related traits. Efforts are now underway to identify the causal variants under the GWAS loci to identify target genes and biological mechanisms underpining AUDs. Many GWAS variants occur in promoter or enhancer regions of the genes and are involved in regulation of gene expression of causal genes. This, large amounts of "omics" data from projects such as "ENCODE", RoadMap and GTEx is also helping researchers to integrate "multi-omics" data to interpret functional significance of GWAS variants.

SUMMARY

With current review, we aim to present the recent advances in genetic and molecular studies of AUDs. Recent successes in genetic studies of AUDs will definetely motivate researchers and lead to better therapeutic interventions for this complex disorder.

Linking Delay Discounting and Substance Use Disorders: Genotypes and Phenotypes

Research supports the idea that "delay discounting," also known as temporal discounting, intertemporal choice, or impulsive choice, is a transdisease process with a strong connection to substance use disorders (SUDs) and other psychopathologies, like attention deficit hyperactivity disorder and depression. This article briefly reviews the evidence used to conclude that delay discounting is heritable and should be considered to be an endophenotype, as well as evidence of its behavioral and genetic associations with SUDs. It also discusses the limitations that should be considered when evaluating the strength of these associations. Finally, this article briefly describes research examining relationships among delay discounting and SUD-associated intermediate phenotypes to better understand the conceptual relationships underlying the links between SUDs and delay discounting, and identifies research gaps that should be addressed.

Evaluating Neighborhood, Social, and Genetic Influences on Precursors of Alcohol Use Risk Behavior in African American Adolescents

Background: Using a socioecological framework, we examined neighborhood and social stressors in concert with genetic risk for alcohol dependence in relation to externalizing behaviors, important precursors to alcohol-related problems. Methods: We used data from African American adolescents and their caregivers in the Gene, Environment, and Neighborhood Initiative, a subsample of the Mobile Youth and Poverty Study. Participants for the current analyses included 112 adolescents who reported ever having at least one full drink of alcohol. Empirical Bayes scores were used to estimate neighborhood-level violence and transitions. Multivariate models tested main effects and then interactions of family stressors, discrimination, and genetic risk with the neighborhood variables. Results: In the main effects model, adolescent externalizing behaviors were positively associated with greater family stressors, more racial discrimination experiences, and genetic liability, while neighborhood variables were nonsignificant. We found three significant interactions. Specifically, the joint effects of neighborhood violence and transitions and between these neighborhood variables and family stressors were significantly associated with externalizing behaviors. Conclusions: Our findings suggest genetic liability and complex interactions between neighborhood context and social stressors are important contributors that should be considered in the development of early prevention programs for adolescents who live in economically disadvantaged areas.

Neighborhood density of alcohol outlets moderates genetic and environmental influences on alcohol problems

BACKGROUND AND AIMS

Geographic differences in rates of alcohol use disorder suggest that environmental factors and gene-environment interactions are likely to play an important role in its genesis. We aimed to examine whether living in a community with more alcohol outlets would facilitate the expression of the genetic propensity to develop alcohol problems.

DESIGN

Cross-sectional twin/sibling study.

SETTING

United States.

PARTICIPANTS

The participants were 18-26-year-old twin, full- and half-sibling pairs from Wave III of the National Longitudinal Study of Adolescent to Adult Health.

MEASUREMENTS

Participants completed in-home interviews in which past year alcohol problems were assessed. Alcohol outlet densities were extracted from state-level liquor license databases aggregated at the census tract level.

FINDINGS

There was evidence that estimates of genetic and environmental influences on alcohol problems varied as a function of the density of alcohol outlets in the community. The heritability of alcohol problems for those residing in a neighborhood with more than 10 on-premises outlets was 78% (95% confidence limits = 52-100%), compared with 11% (95% confidence limits = 0-29%) for those in a neighborhood with no on-premises outlets. This moderating effect of alcohol outlet density was not explained by state of residence, population density or neighborhood socio-demographic characteristics.

CONCLUSIONS

Individuals who are genetically predisposed to develop alcohol problems may be especially sensitive to the influence of many alcohol outlets in their community.

Neighborhood alcohol outlet density and genetic influences on alcohol use: evidence for gene-environment interaction

BACKGROUND

Genetic influences on alcohol involvement are likely to vary as a function of the 'alcohol environment,' given that exposure to alcohol is a necessary precondition for genetic risk to be expressed. However, few gene-environment interaction studies of alcohol involvement have focused on characteristics of the community-level alcohol environment. The goal of this study was to examine whether living in a community with more alcohol outlets would facilitate the expression of the genetic propensity to drink in a genetically-informed national survey of United States young adults.

METHODS

The participants were 2434 18-26-year-old twin, full-, and half-sibling pairs from Wave III of the National Longitudinal Study of Adolescent to Adult Health. Participants completed in-home interviews in which alcohol use was assessed. Alcohol outlet densities were extracted from state-level liquor license databases aggregated at the census tract level to derive the density of outlets.

RESULTS

There was evidence that the estimates of genetic and environmental influences on alcohol use varied as a function of the density of alcohol outlets in the community. For example, the heritability of the frequency of alcohol use for those residing in a neighborhood with ten or more outlets was 74% (95% confidence limits = 55-94%), compared with 16% (95% confidence limits = 0-34%) for those in a neighborhood with zero outlets. This moderating effect of alcohol outlet density was not explained by the state of residence, population density, or neighborhood sociodemographic characteristics.

CONCLUSIONS

The results suggest that living in a neighborhood with many alcohol outlets may be especially high-risk for those individuals who are genetically predisposed to frequently drink.

Shared additive genetic variation for alcohol dependence among subjects of African and European ancestry

Alcohol dependence (AD) affects individuals from all racial/ethnic groups, and previous research suggests that there is considerable variation in AD risk between and among various ancestrally defined groups in the United States. Although the reasons for these differences are likely due in part to contributions of complex sociocultural factors, limited research has attempted to examine whether similar genetic variation plays a role across ancestral groups. Using a pooled sample of individuals of African and European ancestry (AA/EA) obtained through data shared within the Database for Genotypes and Phenotypes, we estimated the extent to which additive genetic similarity for AD between AA and EAs using common single nucleotide polymorphisms overlapped across the two populations. AD was represented as a factor score by using Diagnostic and Statistical Manual dependence criteria, and genetic data were imputed by using the 1000 Genomes Reference Panel. Analyses revealed a significant single nucleotide polymorphism-based heritability of 17 percent (SE = 5) in EAs and 24 percent (SE = 15) in AAs. Further, a significant genetic correlation of 0.77 (SE = 0.46) suggests that the allelic architecture influencing the AD factor for EAs and AAs is largely similar across the two populations. Analyses indicated that investigating the genetic underpinnings of alcohol dependence in different ethnic groups may serve to highlight core etiological factors common to both groups and unique etiological factors specific to each ethnic group.

Examining interactions between genetic risk for alcohol problems, peer deviance, and interpersonal traumatic events on trajectories of alcohol use disorder symptoms among African American college students

Numerous studies have demonstrated that genetic and environmental factors interact to influence alcohol problems. Yet prior research has primarily focused on samples of European descent and little is known about gene–environment interactions in relation to alcohol problems in non-European populations. In this study, we examined whether and how genetic risk for alcohol problems and peer deviance and interpersonal traumatic events independently and interactively influence trajectories of alcohol use disorder symptoms in a sample of African American students across the college years (N = 1,119; Mage= 18.44 years). Data were drawn from the Spit for Science study where participants completed multiple online surveys throughout college and provided a saliva sample for genotyping. Multilevel growth curve analyses indicated that alcohol dependence genome-wide polygenic risk scores did not predict trajectory of alcohol use disorder symptoms, while family history of alcohol problems was associated with alcohol use disorder symptoms at the start of college but not with the rate of change in symptoms over time. Peer deviance and interpersonal traumatic events were associated with more alcohol use disorder symptoms across college years. Neither alcohol dependence genome-wide polygenic risk scores nor family history of alcohol problems moderated the effects of these environmental risk factors on alcohol use disorder symptoms. Our findings indicated that peer deviance and experience of interpersonal traumatic events are salient risk factors that elevate risk for alcohol problems among African American college students. Family history of alcohol problems could be a useful indicator of genetic risk for alcohol problems. Gene identification efforts with much larger samples of African descent are needed to better characterize genetic risk for alcohol use disorders, in order to better understand gene–environment interaction processes in this understudied population.

A systematic review: Candidate gene and environment interaction on alcohol use and misuse among adolescents and young adults

BACKGROUND AND OBJECTIVES

Youth drinking is a pervasive public health concern with serious negative developmental implications. Candidate gene and environment interaction studies (cGxE) show that environmental effects on drinking behaviors may differ by individuals' genotypes. Yet little is known about whether genetic and environmental effects on drinking behaviors are developmentally specific.

METHODS

This systematic review evaluated 42 cGxE studies of drinking in adolescence and young adulthood.

RESULTS

Although there are mixed findings, studies of cGxE effects involving DRD4, 5-HTTLPR, DRD2, and OPRM1 genotypes showed relatively consistent patterns. The effects of under-controlled environments (eg, low levels of parental monitoring) on early and middle adolescent drinking appeared to differ across DRD2 or OPRM1 genotypes. Effects of alcohol-facilitating environments (eg, heavy drinking peers) on late adolescent and young adult drinking appeared to differ across DRD4 or OPRM1 genotypes. Interactions between 5-HTTLPR genotype with stressful environments (eg, negative life events) were found throughout adolescence and young adulthood, although there were some inconsistencies regarding the risk-conferring allele. There was limited evidence for other cGxE effects due to the small number of studies.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

This review suggests that GxE findings may advance our knowledge regarding which developmentally specific conditions result in the expression of candidate genes that influence youth alcohol use and misuse. However, since a significant number of studies had small sample sizes and most studies had small effect sizes, findings need replication across independent studies with large samples. (Am J Addict 2018;XX:1-19).

The Future of Research on Alcohol-Related Disparities Across U.S. Racial/Ethnic Groups: A Plan of Attack

OBJECTIVE

Research suggests striking disparities in alcohol use, problems, and treatment across racial/ethnic groups in the United States. However, research on alcohol-related disparities affecting racial/ethnic minorities remains in its developmental stages. The current article aims to support future research in this growing field by highlighting some of the most important findings, questions, and approaches, focusing on psychosocial research.

METHOD

This article advances seven research needs (i.e., questions and topics meriting attention) that we believe are of crucial importance to the field. We draw on the existing literature to illuminate under-explored areas that are highly relevant to health intervention and that complement the field's existing focus.

RESULTS

Identified research needs include research that (a) better describes disparities in alcohol-related health conditions and their drivers, (b) identifies appropriate screening and brief intervention methods for racial/ethnic minorities, (c) investigates disparities in access to and use of alcohol treatment and support services, (d) examines the comparative efficacy of existing alcohol interventions and develops tailored interventions, (e) explores the impacts of specific alcohol policies across and within racial/ethnic groups, and (f) describes the full spectrum of alcohol-related harms and how and why these may vary across racial/ethnic groups. We also call for (g) continuing research to monitor disparities over time.

CONCLUSIONS

This article points to specific strategies for describing, explaining, intervening on, and monitoring some of the most substantial alcohol-related disparities. Conclusions outline methods and processes that may be advantageous in addressing these priorities, including the use of longitudinal designs; consideration of life course changes; attention to nontraditional intervention settings; and inclusion of disadvantaged populations in all aspects of research.

Commentary: Perspectives on alcohol-related gene and environment interplay in diverse populations

BACKGROUND AND OBJECTIVES

Racial/ethnic groups comprise more than 20% of the U.S. population, but many experience disproportionately high risk for alcohol misuse, often resulting in higher rates of alcohol-associated consequences. Completion of mapping the human genome has launched rapidly evolving research methods aimed at improved understanding of genetic contribution to disease. Despite decades of research on the influence of genetic and environmental risks on alcohol use disorders and outcomes, few studies have included racial/ethnic subpopulations in sufficient numbers to allow for proper statistical analysis.

METHODS

The papers in this special issue help to elucidate current knowledge on the etiology of genetic and environmental contributors and potential moderators of alcohol use and associated problems among racial/ethnic populations. The lack of racial/ethnic diversity across many genetic studies contributes to challenges in interpretation of findings and eventually applications to precision medicine.

RESULTS

Proposed approaches to overcome disparities in racial/ethnic participant recruitment in genetic studies include methods to address population stratification in allele frequency, improve transparency in subjects' consenting to participate, and engaging interdisciplinary research teams and community involvement to improve recruitment of racial/ethnic minorities.

DISCUSSION AND CONCLUSIONS

The reviews presented underscore various gaps in our knowledge of the genetic influences on alcohol use disorders due to the failure to include racially and ethnically diverse populations in genetic and epigenetic study samples. New directions are suggested to overcome the resulting research challenges and ultimately to inform future personalized intervention approaches for racial/ethnic populations.

SCIENTIFIC SIGNIFICANCE

Inclusion of heterogeneous populations in genomic research will provide a better comprehension of possible unique genetic factors in the broader general population that may be missed due to exclusion of unique and common variants that may be present in racial/ethnic populations. (Am J Addict 2017;26:526-531).

Conclusion: Special issue on genetic and alcohol use disorder research with diverse racial/ethnic groups: Key findings and potential next steps

BACKGROUND AND OBJECTIVES

This special issue brings together papers focusing on a wide range of topics relevant to the research and understanding of the role of race/ethnicity and genetic variation for the susceptibility of developing an alcohol use disorder (AUD).

METHODS

The key findings from the issue's 10 articles are reviewed and organized here around three topics: I: addictive behaviors and potential environmental influences; II: a focus on four racial/ethnic groups; and III: special methodologies.

RESULTS

Several potential next steps in improving effective research strategies are highlighted: (1) implementing best practices for outreach and community engagement may reduce reluctance to participate; (2) recruiting adequately sized and racially/ethnically diverse samples will require new collaborations with investigators who successfully work in diverse communities; (3) identifying and assessing environmental influences that are both unique to, and common among, racial/ethnic groups may inform preventions for AUD; (4) use of standardized measures will facilitate the generation of larger samples and meta-analysis of research findings; and (5) use of better analytic approaches and experimental methods will improve replication in gene finding research and help advance new areas of research.

CONCLUSIONS

Genetic research of AUD in diverse racial/ethnic populations is advancing. The articles in this issue examined the general theme of including diverse population groups in genetic studies and offered potential strategies for addressing some common problems.

SCIENTIFIC SIGNIFICANCE

Greater inclusion of diverse racial/ethnic populations in this research is important to ensure that the benefits of new knowledge and technology are equally shared. (Am J Addict 2017;26:532-537).

Introduction: Special issue on genetic research of alcohol use disorder in diverse racial/ethnic populations

This special issue of The American Journal on Addictions is an extension of a workshop held at the Research Society on Alcoholism (2015) highlighting several important issues related to studies of the genetic bases of alcohol use disorder among racially/ethnically diverse populations. While not exhaustive in their coverage, the papers in this special issue focus on three important topics: (1) the importance of considering the social and environmental context in genetic analyses; (2) social and cultural considerations for engaging diverse communities in genetic research; and (3) methodologies related to phenotype development for use with racially/ethnically diverse populations. A brief overview of each paper included in these three sections is presented. The issue concludes with additional considerations for genetic research with racially/ethnically diverse population groups along with a commentary. (Am J Addict 2017;26:422-423).