Genetically informative research on adolescent substance use: methods, findings, and challenges

Factors predicting the intention of drug abuse avoidance among adolescents in Pinlaung Township, Myanmar: predictive correlational design

BACKGROUND

Adolescence is a critical transition period and is at high risk for drug/substance abuse. In Myanmar, drug use is common among adolescents and is a public health concern. There are no studies of drug abuse prevention among Myanmar adolescents. Intentions to avoid drug abuse can be a protective factor for preventing drug abuse among adolescents. This study investigated the effects of sex, parental history of drug/alcohol abuse, self-efficacy, parental marital status, and family functioning on the intention of drug abuse avoidance among Myanmar adolescents.

METHODS

This is a predictive correlational study. The Biopsychosocial model was used as the theoretical framework of this study. A convenient sampling method was used to collect data from 157 students aged 13-18 years in a government school, middle school level and high school level, Pinlaung Town, Southern Shan State, Myanmar during the COVID-19 pandemic and political protests. G* power software was used to calculate the sample size. Data was collected by four self-administered questionnaires: a socio-demographic questionnaire, Thai Family Functioning Scale (TFFS), General Self-Efficacy Scale (GSE), and Intention of Drug Avoidance Scale (IDAS). Multiple linear regression was employed to analyze the data.

RESULTS

Five predictors, including biological sex, parental history without drug/alcohol abuse, self-efficacy, parental marital status, and family functioning, explained 24.4% of the variance in the intention of drug abuse avoidance among Myanmar adolescents (R 2 = .244, F (5,151) = 9.738, p = .000). In addition, only three factors, family functioning (β = .31, p < .001), biological sex (β = -.25, p < .01), and self-efficacy (β = .16, p < .05) statistically and significantly predicted the intention of drug abuse avoidance among Myanmar adolescents.

CONCLUSIONS

Family functioning, female gender, and self-efficacy predicted the intention of drug abuse avoidance among Myanmar adolescents in Pinlaung Township, Southern Shan State, Myanmar.

IMPLICATIONS OF THIS STUDY

The results of this study have implications for all stakeholders through research, education, practice, and policymaking leading to improve the intentions of drug abuse avoidance among Myanmar adolescents. Furthermore, the results of this study specifically contribute to create psychoeducational intervention programs for increasing intention to avoid substance use by promoting family functioning and self-efficacy of adolescents. This is especially proper for male adolescents who have less intention to avoid substance use.

Extending the "Worst of Both Worlds" hypothesis to the developmental antecedents of crime and substance use: school bullying and alcohol experimentation

The "Worst of Both Worlds" (WBW) hypothesis holds that individuals who both commit crime and misuse drugs are at significantly greater risk for future crime and drug problems than individuals who only commit crime or only misuse drugs. In the current investigation, two developmental antecedents of crime and substance use-school bullying and alcohol experimentation-were used to form four WBW conditions (no bullying or alcohol experimentation, alcohol experimentation without bullying, bullying without alcohol experimentation, and bullying with alcohol experimentation). Analyzing data from 3837 (1951 boys, 1886 girls) early adolescents from the Longitudinal Study of Australian Children (mean age = 12.4 years at baseline), it was noted that children who engaged in bullying and had experimented with alcohol by age 12/13 were significantly more likely to increase their involvement in delinquency and substance use by age 16/17 compared to children who did not engage in bullying and had not experimented with alcohol, children who bullied but had not experimented with alcohol, and children who experimented with alcohol but had not bullied. These results not only support the WBW hypothesis, they also suggest that the effect may have developmental origins beyond similarities in externalizing symptomatology.

Promoter Specific Methylation of SSTR4 is Associated With Alcohol Dependence in Han Chinese Males

Alcohol dependence (AD), a disease can be affected by environmental factors with epigenetic modification like DNA methylation changes, is one of the most serious and complex public health problems in China and worldwide. Previous findings from our laboratory using the Illumina Infinium Human Methylation450 BeadChip suggested that methylation at the promoter of SSTR4 was one of the major form of DNA modification in alcohol-dependent populations. To investigate whether DNA methylation levels of the SSTR4 promoter influence alcohol-dependent behaviors, genomic DNA was extracted from the peripheral blood sample of 63 subjects with AD and 65 healthy controls, and pyrosequencing was used to verify the results of BeadChip array. Linear regression was used to analyze the correlation between the methylation levels of SSTR4 promoter and the scores of alcohol dependence scales. Gene expression of SSTR4 in brain tissue was obtained from the Genotype-Tissue Expression (GTEx) project and Human Brain Transcriptome database (HBT). We found the methylation levels of SSTR4 in AD group were significantly lower than healthy controls (two-tailed t-test, t = 14.723, p < 0.001). In addition, only weak to moderate correlations between the methylation levels of the SSTR4 promoter region and scale scores of Alcohol Use Disorders Identification Test (AUDIT), Life Events Scale (LES) and Wheatley Stress Profile (WSS) based on linear regression analyses (AUDIT: R ² = 0.35, p < 0.001; LES: R ² = 0.27, p < 0.001; WSS: R ² = 0.49, p < 0.001). The hypomethylated status of SSTR4 may involve in the development of AD and increase the risk of AD persistence in Han Chinese males.

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.

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.

Depressive symptoms, sexual activity, and substance use among adolescents in Kampala, Uganda

BACKGROUND

Adolescents experience high rates of depression, initiation of sexual activity, and substance use.

OBJECTIVES

To better understand the demographics of adolescents presenting to an adolescent clinic in Uganda, and to elucidate which factors are associated with depressive symptoms, sexual initiation, and substance use.

METHODS

A retrospective review was performed on intake forms obtained during interviews with adolescents presenting to the Makerere/Mulago Columbia Adolescent Health Clinic (MMCAH) in Kampala, Uganda.

RESULTS

Depressive symptoms in adolescents were correlated with having a chronic illness (p=.026), and reported poor quality of home life (p<.001). Initiation of sexual activity was also correlated with chronic illness (p=.008) and poor quality of home life (p=.006). Substance use was correlated with maternal death (p=.041), chronic illness (p=.038), and substance use among family members (p<.001) and friends (p<.001).

CONCLUSIONS

Knowing the aforementioned risk factors can help us better understand the needs of adolescents presenting to MMCAH, and allows us to develop targeted interventions aimed at decreasing health risks in Kampala's adolescent population.

Relation between age at first alcohol drink & adult life drinking patterns in alcohol-dependent patients

Background & objectives:

Age at first drink has its influence on later life drinking patterns. The association between age at first drink and adult alcohol consumption has not been studied in clinical population. This study was aimed to determine the age at first drink and its correlation with adult life drinking patterns in alcohol-dependent patients.

Methods:

Adult participants with alcohol dependence were included from the inpatient and outpatient wards of a tertiary care de-addiction facility in India. Questionnaires administered were National Institute on Alcohol Abuse and Alcoholism-Quantity Frequency for alcohol and the Fagerstrom Test for Nicotine Dependence for tobacco.

Results:

Of the 99 participants (92% males) with mean age 37±8.36 yr, mean age at first drink was 21.14±5.33 yr. After controlling for age, satisfaction with life scores and smoking, age at first drink showed a significant negative correlation with drinking days per week (r=-0.259, P=0.012), typical drink per day (r=-0.218, P=0.035) and maximum drinks in the previous month/year (r=-0.233, -0.223 and P=0.024, 0.031, respectively).

Interpretation & conclusions:

Our study suggested that earlier age of first drink correlated with chronic heavy drinking patterns in later adult life in alcohol-dependent patients. This may have implications for alcohol control policies determining the age for legal consumption.

Assessing Associations in Substance Use across Three Generations: From Grandparents to Sons and from Sons to Their Children

The Three Generational Study (3GS) began in the early 90s and involves the third generation (G3) offspring of second generation (G2) fathers who were originally recruited in 1984 as part of the Oregon Youth Study (OYS) in mid childhood (ages 9-10 years) along with their first- generation (G1) parents. As boys, the G2 fathers lived in higher delinquency neighborhoods of a medium-sized Pacific Northwestern United States city. The OYS-3GS examines questions concerning socially mediated intergenerational transmission versus discontinuity (or moderation) of antisocial behavior, substance use, and related problem behaviors. Questions address influences of the grandparents, or Generation 1 (G1), on their sons in G2 and in turn of these sons and their partners on their own children in G3. In this article, we present an overview of the study design-and underlying theory-related to general and outcome-specific transmission pathways. We then summarize key issues and findings to date related to the current main focus of the study regarding intergenerational associations in substance use.

The utility of twins in developmental cognitive neuroscience research: How twins strengthen the ABCD research design

The ABCD twin study will elucidate the genetic and environmental contributions to a wide range of mental and physical health outcomes in children, including substance use, brain and behavioral development, and their interrelationship. Comparisons within and between monozygotic and dizygotic twin pairs, further powered by multiple assessments, provide information about genetic and environmental contributions to developmental associations, and enable stronger tests of causal hypotheses, than do comparisons involving unrelated children. Thus a sub-study of 800 pairs of same-sex twins was embedded within the overall Adolescent Brain and Cognitive Development (ABCD) design. The ABCD Twin Hub comprises four leading centers for twin research in Minnesota, Colorado, Virginia, and Missouri. Each site is enrolling 200 twin pairs, as well as singletons. The twins are recruited from registries of all twin births in each State during 2006-2008. Singletons at each site are recruited following the same school-based procedures as the rest of the ABCD study. This paper describes the background and rationale for the ABCD twin study, the ascertainment of twin pairs and implementation strategy at each site, and the details of the proposed analytic strategies to quantify genetic and environmental influences and test hypotheses critical to the aims of the ABCD study.

The association of prenatal cocaine exposure, externalizing behavior and adolescent substance use

Prenatal cocaine exposure (PCE) may increase adolescent substance use through alterations of neurotransmitter systems affecting fetal brain development. The relationship between PCE and substance use at 15 and 17 years was examined. Subjects (365: 186 PCE; 179 non-cocaine exposed (NCE)) supplied biologic and self-report data using the Youth Risk Behavior Surveillance System (YRBSS) and Computerized Diagnostic Interview Schedule for Children (C-DISC 4) at ages 15 and 17. The relationship between PCE and substance use was assessed using General Estimating Equation (GEE) analyses controlling for confounding factors including violence exposure and preschool lead level. Teens with PCE vs. NCE teens were 2 times more likely to use tobacco (OR=2.1; 95% CI 1.21-3.63; p<.001) and marijuana (OR=1.85; CI 1.18-2.91; p<.001) and have a substance use disorder at age 17 (OR=2.51; CI 1.00-6.28; p<.05). Evaluation of PCE status by gender revealed an association between PCE and marijuana use that was more pronounced for boys than girls at 17 years. Violence exposure was also a significant predictor of alcohol (p<.001), tobacco (p<.05), and marijuana (p<.0006) use and substance abuse/dependence (p<.01). Externalizing behavior at age 12 fully mediated the effects of PCE on substance use disorder at age 17 and partially mediated effects of PCE on tobacco use, but did not mediate effects on marijuana use. The percentage of substance use reported increased between 15 and 17 years, with no differences between the PCE and NCE groups. Data suggest specialized drug use prevention measures for children with PCE may benefit this high risk group.

Examining the role of psychological distress in linking childhood maltreatment and alcohol use in young adulthood

BACKGROUND AND OBJECTIVES

Childhood maltreatment is related to alcohol use as well as psychological distress in young adulthood. Few studies have examined whether psychological distress mediates the relationship between child maltreatment and alcohol use. We examined the role of psychological distress in linking child maltreatment subtypes (ie, emotional abuse, physical abuse, sexual abuse, neglect) to four patterns of alcohol use, including frequency of alcohol use, binge drinking, alcohol-related problems, and alcohol dependence.

METHODS

We used a community sample of young adults (N = 337), who completed an interview assessing exposure to childhood maltreatment, current psychological distress, and drinking behaviors.

RESULTS

Emotional abuse was associated with psychological distress, whereas psychological distress was related to more pathological drinking behaviors such as alcohol-related problems and alcohol dependence. Subsequent analyses indicated significant mediated effects between emotional abuse and alcohol-related problems and alcohol dependence via psychological distress, even after controlling for demographic factors, other maltreatment subtypes, parental alcoholism, and peer alcohol use.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Findings suggest that among four types of childhood maltreatment, emotional abuse might be the major driver of pathological drinking among child maltreatment victims. Interventions aimed at negative emotionality may be useful in preventing and treating problematic drinking among the victims of childhood emotional abuse.

Contextual risks linking parents' adolescent marijuana use to offspring onset

OBJECTIVE

We studied the extent to which parent marijuana use in adolescence is associated with marijuana use onset in offspring through contextual family and peer risks.

METHOD

Fathers assessed (n=93) since childhood, their 146 offspring (n=83 girls), and offspring's mothers (n=85) participated in a longitudinal study. Using discrete-time survival analysis, fathers' (prospectively measured) and mothers' (retrospective) adolescent marijuana use was used to predict offspring marijuana use onset through age 19 years. Parental monitoring, child exposure to marijuana use, peer deviance, peer marijuana use, and perceptions of parent disapproval of child use were measured before or concurrent with onset.

RESULTS

Parents' adolescent marijuana use was significantly associated with less monitoring, offspring alcohol use, the peer behaviors, exposure to adult marijuana use, and perceptions of less parent disapproval. Male gender and the two peer behaviors were positively associated with children's marijuana use onset, controlling for their alcohol use. Parents' adolescent marijuana use had a significant indirect effect on child onset through children's deviant peer affiliations and a composite contextual risk score.

CONCLUSIONS

Parents' histories of marijuana use may contribute indirectly to children's marijuana use onset through their influence on the social environments children encounter; specifically, those characterized by more liberal use norms, exposure to marijuana use and deviant and marijuana-using peers, and less adult supervision. Given that alcohol use onset was controlled, findings suggest that the contextual factors identified here confer unique risk for child marijuana use onset.

Contextual risks linking parents' adolescent marijuana use to offspring onset

OBJECTIVE

We studied the extent to which parent marijuana use in adolescence is associated with marijuana use onset in offspring through contextual family and peer risks.

METHOD

Fathers assessed (n=93) since childhood, their 146 offspring (n=83 girls), and offspring's mothers (n=85) participated in a longitudinal study. Using discrete-time survival analysis, fathers' (prospectively measured) and mothers' (retrospective) adolescent marijuana use was used to predict offspring marijuana use onset through age 19 years. Parental monitoring, child exposure to marijuana use, peer deviance, peer marijuana use, and perceptions of parent disapproval of child use were measured before or concurrent with onset.

RESULTS

Parents' adolescent marijuana use was significantly associated with less monitoring, offspring alcohol use, the peer behaviors, exposure to adult marijuana use, and perceptions of less parent disapproval. Male gender and the two peer behaviors were positively associated with children's marijuana use onset, controlling for their alcohol use. Parents' adolescent marijuana use had a significant indirect effect on child onset through children's deviant peer affiliations and a composite contextual risk score.

CONCLUSIONS

Parents' histories of marijuana use may contribute indirectly to children's marijuana use onset through their influence on the social environments children encounter; specifically, those characterized by more liberal use norms, exposure to marijuana use and deviant and marijuana-using peers, and less adult supervision. Given that alcohol use onset was controlled, findings suggest that the contextual factors identified here confer unique risk for child marijuana use onset.

Genetic and Environmental Interplay in Adolescent Substance Use Disorders

Adolescent substance use is of considerable public health importance. This narrative review provides a brief background to genetically informative research methodologies and highlights key recent literature examining the interplay between genetic and environmental influences in the etiology of substance use. Twin studies have quantified the magnitude of genetic and environmental influences, and more recently co-relative and Children of Twin designs have shown environments can moderate heritability. Studies have identified a number of specific gene variants (e.g. OPRM1, DRD4, 5HTTLPR) that interact with parenting and peer influence, and the effectiveness of interventions may vary by genotype. However, little research has taken into account the stage-sequential nature of substance use. This may obscure important differences in the genetic and environmental influences, and their interplay, at the stages of escalation to problem use. Future research needs to build on existing methodologies to disentangle the complexities of progression in adolescent substance use.

Intergenerational Hazardous Alcohol Use and Area Factors: The HUNT Study, Norway

BACKGROUND

Alcohol use among adolescents has been found to be associated with parental alcohol abuse, but it's relation to more prevalent forms of hazardous drinking patterns among parents has been less explored. Few studies have included area factors when investigating alcohol use across generations.

OBJECTIVES

The aims of this study were to investigate whether adolescent intoxication was associated with parental heavy episodic drinking (HED) and intoxication, area-level socioeconomic status (SES), and rates of area-level HED.

METHODS

General Estimation Equations (GEE) was applied to analyze data from the Nord-Trøndelag Health Study (2006-08) including 2,306 adolescents. Adolescent alcohol use was defined by self-reported frequency of intoxication. Parental alcohol use was defined by parental self-reports of drinking five glasses of alcohol at one occasion (HED), whether they had been strongly intoxicated, and adolescent reports of seeing parents intoxicated. Area-level SES and HED were based on data from HUNT3 and Statistics Norway.

RESULTS

Parental and offspring alcohol use were associated, although this varied to some extent with gender and exposures. The strongest associations were found between offspring intoxication and offspring reports of seeing their parent intoxicated (girls: OR 3.3, 95% CI 2.3-4.7; boys: OR 3.4, 95% CI 2.4-4.7). Intoxication was more common among girls, who lived in areas with a higher level of adult HED. Living in areas with higher SES was associated with less intoxication among adolescents.

CONCLUSION

Intoxication in adolescence was associated with factors at both family and area level, which emphasize the need of both population and high risk preventive approaches.

An ADH1B variant and peer drinking in progression to adolescent drinking milestones: evidence of a gene-by-environment interaction

BACKGROUND

Adolescent drinking is an important public health concern, one that is influenced by both genetic and environmental factors. The functional variant rs1229984 in alcohol dehydrogenase 1B (ADH1B) has been associated at a genome-wide level with alcohol use disorders in diverse adult populations. However, few data are available regarding whether this variant influences early drinking behaviors and whether social context moderates this effect. This study examines the interplay between rs1229984 and peer drinking in the development of adolescent drinking milestones.

METHODS

One thousand five hundred and fifty European and African American individuals who had a full drink of alcohol before age 18 were selected from a longitudinal study of youth as part of the Collaborative Study on the Genetics of Alcoholism (COGA). Cox proportional hazards regression, with G × E product terms in the final models, was used to study 2 primary outcomes during adolescence: age of first intoxication and age of first DSM-5 alcohol use disorder symptom.

RESULTS

The minor A allele of rs1229984 was associated with a protective effect for first intoxication (HR = 0.56, 95% CI 0.41 to 0.76) and first DSM-5 symptom (HR = 0.45, 95% CI 0.26 to 0.77) in the final models. Reporting that most or all best friends drink was associated with a hazardous effect for first intoxication (HR = 1.81, 95% CI 1.62 to 2.01) and first DSM-5 symptom (HR = 2.17, 95% 1.88 to 2.50) in the final models. Furthermore, there was a significant G × E interaction for first intoxication (p = 0.002) and first DSM-5 symptom (p = 0.01). Among individuals reporting none or few best friends drinking, the ADH1B variant had a protective effect for adolescent drinking milestones, but for those reporting most or all best friends drinking, this effect was greatly reduced.

CONCLUSIONS

Our results suggest that the risk factor of best friends drinking attenuates the protective effect of a well-established ADH1B variant for 2 adolescent drinking behaviors. These findings illustrate the interplay between genetic and environmental factors in the development of drinking milestones during adolescence.

Parental alcohol misuse and hazardous drinking among offspring in a general teenage population: gender-specific findings from the Young-HUNT 3 study

Background

Parental alcohol misuse may negatively affect drinking behaviours among offspring, but it is unclear to what extent influences are gender-specific and dependent upon the actual drinking behaviour measured. The aim of this study was to investigate whether hazardous drinking among Norwegian teenage boys (N = 2538) and girls (N = 2494) was associated with paternal and maternal alcohol misuse (CAGE).

Methods

Definitions of hazardous drinking among offspring were based on self-reported alcohol consumption (in litres a year), frequency of drinking, and frequency of drunkenness. Based on this information, two composite measures of hazardous drinking were also constructed. Cross-sectional data from the Norwegian Young-HUNT 3 survey (2006–2008) were linked to information from biological parents who participated in the adult part of the HUNT study.

Results

Logistic regression analyses showed that both boys and girls with alcohol misusing fathers were more likely to report high levels of alcohol intake compared to others of the same age and gender. This was contrary to boys with misusing mothers, who reported less alcohol consumption than other boys. Among girls, but not boys, high frequency of drunkenness was associated with maternal as well as paternal misuse.

Conclusions

This study suggests that adolescent hazardous drinking is more prevalent among boys and girls with alcohol misusing parents versus those whose parents do not misuse alcohol. However, findings were gender specific and varied depending on the drinking outcomes under investigation. More evidence-based knowledge in this field is of great importance for better understanding the possible role paternal and maternal alcohol misuse may play in the development of hazardous alcohol drinking patterns among adolescent boys and girls.

Overview of Behavioral Genetics Research for Family Researchers

This article provides an overview of the methods, assumptions, and key findings of behavioral genetics methodology for family researchers with a limited background. We discuss how family researchers can utilize and contribute to the behavioral genetics field, particularly in terms of conducting research that seeks to explain shared environmental effects. This can be done, in part, by theoretically controlling for genetic confounds in research that seeks to determine cause-and-effect relationships among family variables and individual outcomes. Gene-environment correlation and interaction are especially promising areas for the family researcher to address. Given the methodological advancements in the field, we also briefly comment on new methods in molecular genetics for studying psychological mental health disorders.

Genetics and epigenetics of alcohol dependence

Alcohol dependence is a severe and common disorder associated with high morbidity and mortality rates. Genetic as well as environmental factors are known to modulate susceptibility to alcohol dependence. There is a growing body of evidence suggesting that this interaction between the genome and the environment is mediated by epigenetic mechanisms, e.g. DNA methylation at CpG sites. Following an introduction of epigenetic regulation of gene transcription, this review will provide an overview over recent genetic and epigenetic findings in the context of alcohol dependence focusing on human studies. Finally, we will discuss the current limitations of epigenetic studies as well as the implications of genetic and epigenetic findings for the development of better treatment and prevention strategies.

Peer deviance, alcohol expectancies, and adolescent alcohol use: explaining shared and nonshared environmental effects using an adoptive sibling pair design

Previous research suggests adolescent alcohol use is largely influenced by environmental factors, yet little is known about the specific nature of this influence. We hypothesized that peer deviance and alcohol expectancies would be sources of environmental influence because both have been consistently and strongly correlated with adolescent alcohol use. The sample included 206 genetically related and 407 genetically unrelated sibling pairs assessed in mid-to-late adolescence. The heritability of adolescent alcohol use (e.g., frequency, quantity last 12 months) was minimal and not significantly different from zero. The associations among peer deviance, alcohol expectancies, and alcohol use were primarily due to shared environmental factors. Of special note, alcohol expectancies also significantly explained nonshared environmental influence on alcohol use. This study is one of few that have identified specific environmental variants of adolescent alcohol use while controlling for genetic influence.

Preliminary evidence for a gene-environment interaction in predicting alcohol use disorders in adolescents

BACKGROUND

Emerging research suggests that genetic influences on adolescent drinking are moderated by environmental factors. The present study builds on molecular-genetic findings by conducting the first analysis of gene-environment interactions in the association between a functional single nucleotide polymorphism (SNP) of the μ-opioid receptor (OPRM1) gene (A118G) and risk of developing an alcohol use disorder (AUD) during adolescence. Specifically, we tested whether variation in parenting practices or affiliation with deviant peers moderated the link between the OPRM1 gene and risk of an AUD.

METHODS

Adolescents reporting European ancestry (N = 104), ages 12 to 19 years (M = 15.60, SD = 1.77), were interviewed to ascertain AUD diagnoses, provided a DNA sample for genetic analyses, and completed measures of parental monitoring and deviant peer affiliation. Logistic regression was used to test the effects of environmental variables and their interactions with OPRM1 genotype as predictors of AUD diagnosis while controlling for age and sex.

RESULTS

Case-control comparisons showed that the proportion of youth with an AUD (n = 18) significantly differed by genotype such that 33.3% of G allele carriers met criteria for an AUD compared to 10.8% of youth who were homozygous for the A allele (p = 0.006). The OPRM1 × parental monitoring (odds ratio = 0.16) and OPRM1 × deviant peer affiliation (odds ratio = 7.64) interactions were significant predictors of AUD risk, such that G allele carriers with high levels of deviant peer affiliation or lower levels of parental monitoring had the greatest likelihood of developing an AUD (p-values <0.01).

CONCLUSIONS

This study provides initial evidence that the association between the A118G SNP of the OPRM1 gene and risk of AUDs is moderated by modifiable factors. These results are limited, however, by the small sample size and require replication.

Four factors for the initiation of substance use by young adulthood: a 10-year follow-up twin and sibling study of marital conflict, monitoring, siblings, and peers

This study examined genetic and environmental influences on associations among marital conflict about the child, parental monitoring, sibling relationship negativity, and peer delinquency during adolescence and initiation of illegal drug use by young adulthood. The sample comprised data collected longitudinally from same-sex sibling pairs and parents when the siblings were 10-18 years old (M = 14.5 and 12.9 years for Child 1 and Child 2, respectively) and 20-35 years old (M = 26.8 and 25.5 years for Child 1 and Child 2, respectively). Findings indicate four factors that explain the initiation of illegal drug use: two shaped by genetic influences and two shaped by environments shared by siblings. The two genetically shaped factors probably have distinct mechanisms: one a child-initiated coercive process in the family and the other parent and peer processes shaped by the child's disclosure. The environmentally influenced factors seem distinctively shaped by poor parental monitoring of both sibs and the effects of siblings on each other's deviancy.

Intergenerational influences on early alcohol use: independence from the problem behavior pathway

Conduct problems are a general risk factor for adolescent alcohol use. However, their role in relation to alcohol-specific risk pathways of intergenerational transmission of alcohol use is not well understood. Further, the roles of alcohol-specific contextual influences on children's early alcohol use have been little examined. In a 20-year prospective, multimethod study of 83 fathers and their 125 children, we considered the predictors of child alcohol use by age 13 years. The predictors included fathers' adolescent antisocial behavior and alcohol use, both parents' adult alcohol use, norms about and encouragement of child use, parental monitoring, child-reported exposure to intoxicated adults, and parent-reported child externalizing behaviors. Path models supported an association between fathers' adolescent alcohol use and children's use (β = 0.17) that was not better explained by concurrent indicators of fathers' and children's general problem behavior. Fathers' and mothers' adult alcohol use uniquely predicted child use, and exposure to intoxicated adults partially mediated the latter path. Other family risk mechanisms were not supported. However, parental alcohol use and child alcohol use were linked in expected ways with family contextual conditions known to set the stage for alcohol use problems later in adolescence.

Maternal predictors of comorbid trajectories of cigarette smoking and marijuana use from early adolescence to adulthood

This is the first study to examine maternal predictors of comorbid trajectories of cigarette smoking and marijuana use from adolescence to adulthood. Participants (N=806) are part of an on-going longitudinal psychosocial study of mothers and their children. Mothers were administered structured interviews when participants were adolescents, and participants were interviewed at six time waves, from adolescence to adulthood. Mothers and participants independently reported on their relationships when participants were X¯ age 14.1 years. At each time wave, participants answered questions about their cigarette and marijuana use from the previous wave to the present. Latent growth mixture modeling determined the participants' membership in trajectory groups of comorbid smoking and marijuana use, from X¯ ages 14.1 to 36.6 years. Multivariate logistic regression was used to assess the association of maternal factors (when participants were adolescents) with participants' comorbid trajectory group membership. Findings showed that most maternal risk (e.g., mother-child conflict, maternal smoking) and protective (e.g., maternal affection) factors predicted participants' membership in trajectory groups of greater and lesser comorbid substance use, respectively. Clinical implications include the importance of addressing the mother-child relationship in prevention and treatment programs for comorbid cigarette smoking and marijuana use.