Interaction between dopamine D2 receptor genotype and parental rule-setting in adolescent alcohol use: evidence for a gene-parenting interaction

Associations of parenting styles with substance use in the offspring-A systematic review and meta-analysis

ISSUES

Parenting styles have been suggested to predict the use of psychoactive substances in the offspring, although the size of associations might vary between cultures. The present meta-analysis tested whether parenting styles show concurrent and longitudinal associations with substance use and whether this association is moderated by study characteristics.

APPROACH

A systematic search in electronic data bases resulted in 184 studies that were included in multi-level meta-analysis.

KEY FINDINGS

An authoritative parenting style correlated with lower substance use (r =-0.12, confidence interval [CI] -0.14 to -0.10) while the reverse was found for neglectful (r = 0.10, CI 0.08 to 0.13), permissive (r = 0.04, CI 0.01 to 0.07) and authoritarian parenting (r = 0.03, CI 0.00 to 0.05). Analysis of cross-lagged effects found only an effect of authoritative parenting on decline of substance use (r = -0.06, CI -0.12 to -0.00). The size of associations varied, in part, by levels of horizontal and vertical collectivism or individualism, assessment of three versus four parenting styles, type of substance, and use of same versus different informants for assessing parenting and substance use.

IMPLICATIONS

Parenting styles show small to very small associations with substance use.

CONCLUSIONS

Although parents are recommended to behave in an authoritative manner, we should have only modest expectations about the effects of parenting styles on substance use in the offspring.

Candidate gene-environment interactions in substance abuse: A systematic review

BACKGROUND

The abuse of psychogenic drugs can lead to multiple health-related problems. Genetic and environmental vulnerabilities are factors in the emergence of substance use disorders. Empirical evidence regarding the gene-environment interaction in substance use is mixed. Summaries of the latest findings from a candidate gene approach will be useful for revealing the significance of particular gene contributions. Thus, we aim to identify different gene-environment interactions in patterns of substance use and investigate whether any effects trend notably across different genders and races.

METHODS

We reviewed published studies, until March 1, 2022, on substance use for candidate gene-environment interaction. Basic demographics of the included studies, target genes, environmental factors, main findings, patterns of gene-environment interaction, and other relevant information were collected and summarized.

RESULTS

Among a total of 44 studies, 38 demonstrated at least one significant interaction effect. About 61.5% of studies on the 5-HTTLPR gene, 100% on the MAOA gene, 42.9% on the DRD2 gene, 50% on the DRD4 gene, 50% on the DAT gene, 80% on the CRHR1 gene, 100% on the OPRM1 gene, 100% on the GABRA1 gene, and 50% on the CHRNA gene had a significant gene-environment interaction effect. The diathesis-stress model represents a dominant interaction pattern (89.5%) in the studies with a significant interaction effect; the remaining significant effect on substance use is found in the differential susceptibility model. The social push and swing model were not reported in the included studies.

CONCLUSION

The gene-environment interaction research on substance use behavior is methodologically multidimensional, which causes difficulty in conducting pooled analysis, or stated differently-making it hard to identify single sources of significant influence over maladaptive patterns of drug taking. In decreasing the heterogeneity and facilitating future pooled analysis, researchers must (1) replicate the existing studies with consistent study designs and measures, (2) conduct power calculations to report gene-environment correlations, (3) control for covariates, and (4) generate theory-based hypotheses with factorial based experiments when designing future studies.

Early parent-child interactions and substance use disorder: An attachment perspective on a biopsychosocial entanglement

This review aims to elucidate environmental and genetic factors, as well as their epigenetic and neuroendocrine moderators, that may underlie the association between early childhood experiences and Substance Use Disorders (SUD), through the lens of parental attachment. Here we review those attachment-related studies that examined the monoaminergic systems, the hypothalamic pituitary adrenal stress response system, the oxytoninergic system, and the endogenous opioid system from a genetic, epigenetic, and neuroendocrine perspective. Overall, the selected studies point to a moderating effect of insecure attachment between genetic vulnerability and SUD, reasonably through epigenetic modifications. Preliminary evidence suggests that vulnerability to SUDs is related with hypo-methylation (e.g. hyper-expression) of high-risk polymorphisms on the monoaminergic and hypothalamic pituitary adrenal system and hyper-methylation (e.g. hypo-expressions) of protective polymorphisms on the opioid and oxytocin system. These epigenetic modifications may induce a cascade of neuroendocrine changes contributing to the subclinical and behavioural manifestations that precede the clinical onset of SUD. Protective and supportive parenting could hence represent a key therapeutic target to prevent addiction and moderate insecure attachment.

Alcohol use disorders among adult children of alcoholics (ACOAs): Gene-environment resilience factors

Both genetic and early environmental factors contribute to the pathogenesis of Alcohol Use Disorder (AUD). Gender and psychopathology symptoms might further moderate this association, resulting in an impairment of both the dopaminergic and serotoninergic pathways that sustain the binge, withdrawal and craving cycle. In a sample of of adult children of alcoholic parents (ACOAs) (n = 107) we compared those with and without an AUD, on socio-demographic variables, adverse childhood experiences, psychopathology symptoms and two polymorphisms associated with an impaired serotoninergic and dopaminergic neurotransmission (5HTTLPR and Taq1A/DRD2). A logistic regression revealed that an early caring environment might lower the risk of developing an AUD. When controlling for the actual psychopathology symptoms, being male and having the genotype associated with an impaired dopaminergic neurotransmission were still associated with AUD. Results were confirmed by an unsupervised approach that showed how the clusters characterised by being male and having the high risk genotypes were still associated with AUD compared to being female without the unfavourable dopamine genotype.Our results point to the need for implementing prevention strategies aimed at creating a caring environment especially in those families with an alcoholic parent. We further suggest that psycho-education as a symptom recognition and avoiding self-medication could improve the outcome in those subjects at higher risk, especially males.

Epistatic effect of Ankyrin repeat and kinase domain containing 1 - Dopamine receptor D2 and catechol-o-methyltransferase single nucleotide polymorphisms on the risk for hazardous use of alcohol in Lithuanian population

AIM

The Lithuanian population has outstanding rates of alcohol consumption and alcohol related mortality. Alteration of brain dopaminergic system play a role in the risk for addiction disorders. We evaluated the association of one single nucleotide polymorphism rs1800497 in the Ankyrin Repeat and Kinase Domain Containing 1 - Dopamine Receptor D2 complex (ANKK1-DRD2) and a catechol-o-methyltransferase (COMT) rs4680 single nucleotide polymorphism with the risk for alcohol use disorder and impulsiveness in Lithuanian population. Both genetic polymorphisms are known to alter brain dopaminergic activity, thus we also investigated the possible interaction effect of these polymorphisms.

METHODS

The study included 329 participants recruited from the local community. Hazardous alcohol use was evaluated using the Alcohol Use Disorder Identification Test (AUDIT). Impulsiveness was measured using the Barratt Impulsiveness Scale - 11 (BIS-11). Between group differences of AUDIT and BIS-11 scores were examined stratified by genetic polymorphisms and their combinations. The independent effect of each polymorphism and their interaction for hazardous alcohol use were evaluated using adjusted logistic regression analyses.

RESULTS

The ANKK1-DRD2 rs1800497 polymorphism was associated with total AUDIT score, but not with the hazardous use of alcohol, as indicated by the AUDIT test cut-off of 8. The COMT rs4680 GG genotype was associated with the hazardous use of alcohol (adjusted OR = 2.094, p = 0.029), but this association was not statistically significant after adjustment for multiple comparisons. Presence of both COMT rs4680 and ANKK1-DRD2 rs1800497 GGxCT/TT polymorphisms was associated with significantly increased risk for hazardous use of alcohol (adjusted OR = 5.016, p = 0.005). The COMT rs4680 and ANKK1-DRD2 rs1800497 genetic polymorphisms, and their combination were not associated with impulsiveness.

CONCLUSIONS

Our study demonstrated that the interaction of COMT rs4680 and ANKK1-DRD2 rs1800497 genetic polymorphisms is associated with a hazardous use of alcohol.

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.

Application of Research Domain Criteria to childhood and adolescent impulsive and addictive disorders: Implications for treatment

The Research Domain Criteria (RDoC) initiative provides a large-scale, dimensional framework for the integration of research findings across traditional diagnoses, with the long-term aim of improving existing psychiatric treatments. A neurodevelopmental perspective is essential to this endeavor. However, few papers synthesizing research findings across childhood and adolescent disorders exist. Here, we discuss how the RDoC framework may be applied to the study of childhood and adolescent impulsive and addictive disorders in order to improve neurodevelopmental understanding and to enhance treatment development. Given the large scope of RDoC, we focus on a single construct highly relevant to addictive and impulsive disorders - initial responsiveness to reward attainment. Findings from genetic, molecular, neuroimaging and other translational research methodologies are highlighted.

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).

Association between Polymorphisms of the DRD2 and ANKK1 Genes and Suicide Attempt: A Preliminary Case-Control Study in a Mexican Population

BACKGROUND

The aim of this study was to analyze the possible association of polymorphic variants of the DRD2 and ANKK1 genes with suicide attempt in a Mexican population.

METHODS

We conducted a case-control study in 289 subjects (166 suicide attempters and 123 healthy controls). We genotyped 2 polymorphisms of DRD2 (rs6275 and rs1799978) and 1 polymorphism of ANKK1 (rs1800497); then we analyzed the association between suicide attempt and these polymorphisms through genotypes, alleles, and inheritance models.

RESULTS

Individuals who carried the TT genotype of the rs1800497 showed a 3-fold risk of attempting suicide (OR = 3.01; 95% CI 1.56-5.81, p = 0.001) when evaluated through the recessive model. In an analysis stratified by gender, this risk factor remained present among females (OR = 2.81; 95% CI 1.37-5.75) as well as males (OR = 3.3; 95% CI 1.01-10.77).

CONCLUSION

Our results suggest that the rs1800497 variant of the ANKK1 gene could increase the risk of suicide attempt in a Mexican population. However, further studies using larger samples are necessary to obtain more conclusive results.

Associations between alcohol dehydrogenase genes and alcohol use across early and middle adolescence: Moderation × Preventive intervention

Data from the in-school sample of the PROSPER preventive intervention dissemination trial were used to investigate associations between alcohol dehydrogenase genes and alcohol use across adolescence, and whether substance misuse interventions in the 6th and 7th grades (targeting parenting, family functioning, social norms, youth decision making, and peer group affiliations) modified associations between these genes and adolescent use. Primary analyses were run on a sample of 1,885 individuals and included three steps. First, we estimated unconditional growth curve models with separate slopes for alcohol use from 6th to 9th grade and from 9th to 12th grade, as well as the intercept at Grade 9. Second, we used intervention condition and three alcohol dehydrogenase genes, 1B (ADH1B), 1C (ADH1C), and 4 (ADH4) to predict variance in slopes and intercept. Third, we examined whether genetic influences on model slopes and intercepts were moderated by intervention condition. The results indicated that the increase in alcohol use was greater in early adolescence than in middle adolescence; two of the genes, ADH1B and ADH1C, significantly predicted early adolescent slope and Grade 9 intercept, and associations between ADH1C and both early adolescent slope and intercept were significantly different across control and intervention conditions.

Dopamine and serotonin genetic risk scores predicting substance and nicotine use in attention deficit/hyperactivity disorder

Individuals with attention deficit/hyperactivity disorder (ADHD) are at increased risk of developing substance use disorders (SUDs) and nicotine dependence. The co-occurrence of ADHD and SUDs/nicotine dependence may in part be mediated by shared genetic liability. Several neurobiological pathways have been implicated in both ADHD and SUDs, including dopamine and serotonin pathways. We hypothesized that variations in dopamine and serotonin neurotransmission genes were involved in the genetic liability to develop SUDs/nicotine dependence in ADHD. The current study included participants with ADHD (n = 280) who were originally part of the Dutch International Multicenter ADHD Genetics study. Participants were aged 5-15 years and attending outpatient clinics at enrollment in the study. Diagnoses of ADHD, SUDs, nicotine dependence, age of first nicotine and substance use, and alcohol use severity were based on semi-structured interviews and questionnaires. Genetic risk scores were created for both serotonergic and dopaminergic risk genes previously shown to be associated with ADHD and SUDs and/or nicotine dependence. The serotonin genetic risk score significantly predicted alcohol use severity. No significant serotonin × dopamine risk score or effect of stimulant medication was found. The current study adds to the literature by providing insight into genetic underpinnings of the co-morbidity of ADHD and SUDs. While the focus of the literature so far has been mostly on dopamine, our study suggests that serotonin may also play a role in the relationship between these disorders.

Allelic Variation of Risk for Anxiety Symptoms Moderates the Relation Between Adolescent Safety Behaviors and Social Anxiety Symptoms

Social anxiety often develops in adolescence, and precedes the onset of depression and substance use disorders. The link between social anxiety and use of behaviors to minimize distress in social situations (i.e., safety behaviors) is strong and for some patients, this link poses difficulty for engaging in, and benefiting from, exposure-based treatment. Yet, little is known about whether individual differences may moderate links between social anxiety and safety behaviors, namely variations in genetic alleles germane to anxiety. We examined the relation between adolescent social anxiety and expressions of safety behaviors, and whether allelic variation for anxiety moderates this relation. Adolescents (n=75; ages 14-17) were recruited from two larger studies investigating measurement of family relationships or adolescent social anxiety. Adolescents completed self-report measures about social anxiety symptoms and use of safety behaviors. They also provided saliva samples to assess allelic variations for anxiety from two genetic polymorphisms (BDNF rs6265; TAQ1A rs1800497). Controlling for adolescent age and gender, we observed a significant interaction between social anxiety symptoms and allelic variation (β=0.37, t=2.41, p=.02). Specifically, adolescents carrying allelic variations for anxiety evidenced a statistically significant and relatively strong positive relation between social anxiety symptoms and safety behaviors (β=0.73), whereas adolescents not carrying allelic variation evidenced a statistically non-significant and relatively weak relation (β=0.22). These findings have important implications for treating adolescent social anxiety, in that we identified an individual difference variable that can be used to identify people who evidence a particularly strong link between use of safety behaviors and expressing social anxiety.

Alcohol Expectancies Mediate and Moderate the Associations between Big Five Personality Traits and Adolescent Alcohol Consumption and Alcohol-Related Problems

Personality and expectancies are relevant psychological factors for the development of adolescent alcohol use and misuse. The present study examined their direct, mediated and moderated effects on different drinking behaviors in adolescence. Personality domains of the five-factor model, positive and negative alcohol expectancies (AEs), alcohol use during the week and the weekend, and alcohol-related problems were assessed in a sample of 361 adolescents. Different personality dimensions were directly associated with specific alcohol outcomes: Extraversion, low Conscientiousness and low Openness were associated with weekend alcohol use; low Agreeableness was related to weekday use; whereas low Agreeableness, low Conscientiousness and Extraversion were associated with alcohol-related problems. In addition, positive AEs mediated the relationship between Extraversion and alcohol use, whereas both positive and negative expectancies mediated the association between Neuroticism and alcohol consumption and alcohol-related problems. Finally, both types of expectancies interacted with Extraversion to predict alcohol problems. Our results highlight the importance of examining the complex interplay of comprehensive personality models and AEs to gain a better understanding of the development of different alcohol use and misuse patterns in adolescence.

Parental smoke exposure and the development of nicotine craving in adolescent novice smokers: the roles of DRD2, DRD4, and OPRM1 genotypes

BACKGROUND

Among adolescent novice smokers, craving is often the first, and is the most reported, symptom of nicotine dependence. Until now, little has been known about the development of craving symptoms in novice smokers. The aim of this study was to identify specific genetic (i.e., DRD2 Taq1A, DRD4 48 bp VNTR, and OPRM1 A118G polymorphisms) and environmental mechanisms that underlie the emergence of both cue-induced and cognitive craving among adolescent novice smokers.

METHOD

A five-wave longitudinal, genetically-informed survey study was conducted with intervals of four months. The sample included 376 early adolescent smokers (12-13 years of age at baseline). Self-report questionnaires were completed regarding smoking behavior, observed parental smoking behavior, and both cue-induced and cognitive craving.

RESULTS

Data were analyzed with a latent growth curve approach. For both cue-induced and cognitive craving, significant interaction effects were found for DRD2 Taq1A with parental smoke exposure. A1-allele carriers did not seem to be influenced by the environment with regard to craving development. Adolescents who are homozygous for the A2-allele and who are more exposed to parental smoking experience the highest levels of both types of craving over time. No significant interaction effects were found between parental smoke exposure and DRD4 48 bp VNTR or OPRM1 A118G.

CONCLUSIONS

Previous studies identified DRD2 Taq1A A1-allele carriers as vulnerable to developing nicotine dependence. However, this study showed that parental smoking increased the chances of developing dependence more rapidly for early adolescents who are considered to be less sensitive to the rewarding effects of nicotine according to their DRD2 Taq1A genotype. It is thus especially important that these young people not be exposed to smoking in their social environment.

The Molecular Neurobiology of Twelve Steps Program & Fellowship: Connecting the Dots for Recovery

There are some who suggest that alcoholism and drug abuse are not diseases at all and that they are not consequences of a brain disorder as espoused recently by the American Society of Addiction Medicine (ASAM). Some would argue that addicts can quit on their own and moderate their alcohol and drug intake. When they present to a treatment program or enter the 12 Step Program & Fellowship, many addicts finally achieve complete abstinence. However, when controlled drinking fails, there may be successful alternatives that fit particular groups of individuals. In this expert opinion, we attempt to identify personal differences in recovery, by clarifying the molecular neurobiological basis of each step of the 12 Step Program. We explore the impact that the molecular neurobiological basis of the 12 steps can have on Reward Deficiency Syndrome (RDS) despite addiction risk gene polymorphisms. This exploration has already been accomplished in part by Blum and others in a 2013 Springer Neuroscience Brief. The purpose of this expert opinion is to briefly, outline the molecular neurobiological and genetic links, especially as they relate to the role of epigenetic changes that are possible in individuals who regularly attend AA meetings. It begs the question as to whether "12 steps programs and fellowship" does induce neuroplasticity and continued dopamine D2 receptor proliferation despite carrying hypodopaminergic type polymorphisms such as DRD2 A1 allele. "Like-minded" doctors of ASAM are cognizant that patients in treatment without the "psycho-social-spiritual trio," may not be obtaining the important benefits afforded by adopting 12-step doctrines. Are we better off with coupling medical assisted treatment (MAT) that favors combining dopamine agonist modalities (DAM) as possible histone-deacetylase activators with the 12 steps followed by a program that embraces either one or the other? While there are many unanswered questions, at least we have reached a time when "science meets recovery," and in doing so, can further redeem joy in recovery.

Emergence of sex differences in the development of substance use and abuse during adolescence

Substance use and abuse begin during adolescence. Male and female adolescent humans initiate use at comparable rates, but males increase use faster. In adulthood, more men than women use and abuse addictive drugs. However, some women progress more rapidly from initiation of use to entry into treatment. In animal models, adolescent males and females consume addictive drugs similarly. However, reproductively mature females acquire self-administration faster, and in some models, escalate use more. Sex/gender differences exist in neurobiologic factors mediating both reinforcement (dopamine, opioids) and aversiveness (CRF, dynorphin), as well as intrinsic factors (personality, psychiatric co-morbidities) and extrinsic factors (history of abuse, environment especially peers and family) which influence the progression from initial use to abuse. Many of these important differences emerge during adolescence, and are moderated by sexual differentiation of the brain. Estradiol effects which enhance both dopaminergic and CRF-mediated processes contribute to the female vulnerability to substance use and abuse. Testosterone enhances impulsivity and sensation seeking in both males and females. Several protective factors in females also influence initiation and progression of substance use including hormonal changes of pregnancy as well as greater capacity for self-regulation and lower peak levels of impulsivity/sensation seeking. Same sex peers represent a risk factor more for males than females during adolescence, while romantic partners increase risk for women during this developmental epoch. In summary, biologic factors, psychiatric co-morbidities as well as personality and environment present sex/gender-specific risks as adolescents begin to initiate substance use.

Gene-environment interactions in common mental disorders: an update and strategy for a genome-wide search

A decade of research has demonstrated the explanatory potential of interplay between genetic variants and environmental factors in the development of common mental disorders. Initial findings have undergone tests of replicability and specificity. Some gene-environment interactions have been confirmed, some have not replicated and yet other turned out to be more specific than initially thought. Specific and complementary roles of genetic factors have been delineated: a common functional length polymorphism in the serotonin transporter gene (5-HTTLPR) moderated the effect of childhood maltreatment on chronic depression in adulthood, but did not substantially influence the effects of adult stressful life events on the onset of new depressive episodes; in contrast, a common functional polymorphism in the brain-derived neurotrophic factor gene (BDNF) moderated the effect of stressful life events in adulthood in triggering new depressive episodes, but did not influence the effects of childhood maltreatment. Molecular mechanisms underlying gene-environment interactions are being uncovered, including DNA methylation and other epigenetic modifications. New gene-environment interactions continue to be reported, still largely from hypothesis-driven research. Statistical and biological prioritization strategies are proposed to facilitate a systematic discovery of novel gene-environment interactions in genome-wide analyses.

Dual growth of adolescent smoking and drinking: evidence for an interaction between the mu-opioid receptor (OPRM1) A118G polymorphism and sex

Smoking and alcohol use often co-occur during adolescence, but little is known about the codevelopment of these substances. In the search for etiological factors that help to explain the development of adolescent substance use patterns, studies have revealed substantial heritability for both alcohol use and smoking. In this regard, the µ-opioid receptor gene (OPRM1, chromosome 6q24-q25) has been linked to both substances. This study examined the predictive relationships between initial level and growth of smoking and drinking in 311 early adolescents (13-15 years old) over a 4-year period. In addition, the effects of the A118G polymorphism of the OPRM1 gene on the initial values and the development over time of alcohol use and smoking were assessed. Finally, as prevalence and heritability estimates for both alcohol- and smoking-related behaviors differ between males and females, OPRM1 by sex interactions were tested. We found that high initial levels of early adolescent alcohol consumption were related to a stronger increase in smoking levels over time. In contrast, high initial levels of smoking were not related to growth of alcohol use. No main OPRM1 effects were found, but sex-specificity of the gene was found for smoking development. Male A-allele carriers showed a faster development in smoking behavior, whereas in females, the G-allele led to a faster development in smoking. Thus, in addition to high levels of alcohol as a risk factor for the development of smoking behavior, sex-specific effects exist for OPRM1, which may additionally have consequences for the development of adolescent smoking.

The developmental psychopathology of alcohol use and alcohol disorders: research achievements and future directions

The last 25 years have seen significant advances in our conceptualization of alcohol use and alcohol use disorders within a developmental framework, along with advances in our empirical understanding that have been potentiated by advances in quantitative methods. These include advances in understanding the heterogeneity of trajectories of alcohol outcomes; new insights about early childhood antecedents, and adolescence and emerging adulthood as important developmental periods for alcohol outcomes; a more nuanced understanding of the influences of developmental transitions, and their timing and contexts; a greater appreciation for the importance of considering multiple levels of analysis (including an increasing number of genetically informative studies); a continuing focus on studying multiple pathways underlying alcohol outcomes; and an increasing focus on studying the effects of alcohol exposure on future development. The current paper reviews these advances and suggests directions for future study.

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.

Smoking-specific parenting and smoking onset in adolescence: the role of genes from the dopaminergic system (DRD2, DRD4, DAT1 genotypes)

Although only few studies have shown direct links between dopaminergic system genes and smoking onset, this does not rule out the effect of a gene-environment interaction on smoking onset. Therefore, the aim of this study was to examine the associations between smoking-specific parenting (i.e., frequency and quality of communication and house rules) and smoking onset while considering the potential moderating role of dopaminergic system genes (i.e., DRD2, DRD4, and DAT1 genotypes). Data from five annual waves of the 'Family and Health' project were used. At time 1, the sample comprised 365 non-smoking adolescents (200 younger adolescents, mean age = 13.31, SD = .48; 165 older adolescents, mean age = 15.19, SD = .57). Advanced longitudinal analyses were used (i.e., logistic regression analyses, (dual) latent growth curves, and cross-lagged path models). The results showed a direct effect of quality of communication on smoking onset. No direct effects were found for frequency of communication and house rules. Furthermore, no direct and moderating effects of the DRD2, DRD4, or DAT1 genotypes were found. In conclusion, the findings indicated that the effects of smoking-specific parenting on smoking are similar for adolescent carriers and non-carriers of the dopaminergic system genes.

COMT Val158Met modulates the effect of childhood adverse experiences on the risk of alcohol dependence

Genetic factors and childhood adverse experiences contribute to the vulnerability to alcohol dependence. However, empirical data on the interplay between specific genes and adverse experiences are few. The COMT Val158Met and DRD2/ANKK1 Taq1A genotypes have been suggested to affect both stress sensitivity and the risk for alcohol dependence. This study tested the hypothesis that genetic variation in COMT Val158Met and DRD2/ANKK1 Taq1A interacts with childhood adverse experiences to predict alcohol dependence. Male abstinent alcohol-dependent patients (n = 110) and age-matched healthy male controls (n = 99) were genotyped for the COMT Val158Met and the DRD2/ANKK1 Taq1A genotypes. Childhood adverse events were measured using three self-report questionnaires. Alcohol dependence severity, age of onset and duration of alcohol dependence were analyzed as secondary outcome measures. Statistical analysis involved logistic regression analysis and analysis of variance. Alcohol-dependent patients reported increased childhood adversity. The interaction between childhood adversity and the COMT Val158Met genotype added significantly to the prediction model. This gene-environment interaction was confirmed in the analysis of the secondary outcome measures, i.e. alcohol dependence severity, age of onset and duration of alcohol dependence. The DRD2/ANKK1 Taq1A genotype was not related to alcohol dependence, nor did it interact with childhood adversity in predicting alcohol dependence. This study provides evidence for a gene-environment interaction in alcohol dependence, in which an individual's sensitivity to childhood adverse experience is moderated by the COMT genotype. Exposed carriers of a low-activity Met allele have a higher risk to develop severe alcohol dependence than individuals homozygous for the Val allele.

Interaction of the TaqIA polymorphism and poor parental socialization on changes in adolescent marijuana use

The current study uses data from the genetic subsample from the National Longitudinal Study of Adolescent Health (Add Health) in waves I and II (ages of 11-19 and 12-20 respectively) to investigate the interaction of the TaqIA polymorphism and poor parental socialization on changes in adolescent marijuana use. Results reveal that TaqIA interacts with poor parental rule setting, but not quality of mother-child communication, to influence changes in marijuana use. Adolescents who are homozygous for the A1 and whose parents allow the youth to set their own curfew experience significant increases in marijuana use during adolescence. In contrast, youths with the A1/A1 genotype whose parents do not allow the adolescent to set their own curfew experience significant decreases in the frequency of marijuana use. These results suggest that direct parental social control may effectively suppress the genetic risk of the A1/A1 genotype on marijuana use in adolescence. The study's limitations are noted.

The interplay between parental monitoring and the dopamine D4 receptor gene in adolescent cannabis use

BACKGROUND

Both environmental risk and genetic variation is believed to play a role in substance use. A candidate environmental variable is parenting. Recent studies have found support for the idea that the dopamine system affects the susceptibility to environmental influences. In the present study we will examine the interplay between effects of parental monitoring and the presence of the DRD4 7-repeat allele in adolescent lifetime cannabis use and the developmental course of cannabis use.

METHODS

A total of 311 adolescents participated in a five-wave longitudinal design. First, we conducted logistic regression analyses to examine the prospective associations between parental monitoring, the DRD4 polymorphism, their interaction and lifetime cannabis use. Second, individual growth parameters were calculated for frequency of cannabis use. Linear regression was used to assess the relationship between parental monitoring, the DRD4 polymorphism, their interaction, and the frequency of cannabis use.

RESULTS

There were no significant main effects of parental monitoring or the DRD4 polymorphism. However, both analyses showed that over a period of four years, a) when experiencing low levels of parental monitoring, individuals with the 7-repeat allele were more likely to show lifetime cannabis use and a stronger increase in frequency of cannabis use than individuals without this allele; b) when experiencing high levels of parental monitoring, individuals with the 7-repeat allele were less likely to show lifetime cannabis use and they showed a smaller increase in frequency of cannabis use than individuals without the 7-repeat allele.

CONCLUSIONS

This study shows that carriers of the DRD4 7-repeat allele are disproportionally affected by the negative and positive effects of parental monitoring such that carriers of the DRD4 7-repeat allele, as compared to non-carriers, are more likely to use cannabis when levels of parental monitoring are low, and less likely to use cannabis when parental monitoring levels are high.

The moderating effect of alcohol-specific parental rule-setting on the relation between the dopamine D2 receptor gene (DRD2), the μ-opioid receptor gene (OPRM1) and alcohol use in young adolescents

AIMS

The main aim of the study was to test the moderating effect of two genetic polymorphisms, one in the dopamine D2 receptor gene (DRD2) and one in the mu-opioid receptor gene (OPRM1), on the link between parental rule-setting and adolescent alcohol use.

METHODS

A total of 214 adolescents (M(age )=13.7, 44.9% male) provided saliva samples and completed survey items describing alcohol use and parental rule-setting.

RESULTS

Findings indicated that alcohol-specific parental rule-setting was more robustly associated with alcohol use for adolescents with the DRD2 A1 risk allele and for those with the OPRM1 G-allele.

CONCLUSION

This study replicates the interaction between parental rule-setting and the DRD2 risk allele on adolescent alcohol use and extends the literature by demonstrating the moderating effects of the OPRM1 risk allele on the link between parental rule-setting and adolescent alcohol use.

Parental alcohol-specific rules and alcohol use from early adolescence to young adulthood

BACKGROUND

  Several studies stress the importance of alcohol-specific rules during adolescence to prevent them from drinking early and heavily. However, most studies have short follow-up periods and do not cover the relevant developmental period in which direct parental control diminishes and adolescent alcohol use increases. The current study aimed to provide a developmental perspective on the link between alcohol-specific rules and alcohol use from early adolescence until early adulthood in the Netherlands.

METHODS

  The sample consisted of 428 Dutch families including fathers, mothers and adolescents from 2 age groups (13 and 15 years old) at Time 1 (T1), who have been surveyed annually for 6 years. To address the effect of alcohol-specific rules on adolescent alcohol use over time, a latent growth curve analytic approach with time-varying covariates was employed.

RESULTS

  Over time, adolescent alcohol use increased, whereas alcohol-specific rules decreased. Most importantly, however, the lagged paths of alcohol-specific rules consistently predicted subsequent alcohol use across the 6 assessments for both younger and older siblings. Thus, strict alcohol-specific rules at a certain point in time were related to a lower intensity of adolescent alcohol use a year later.

CONCLUSIONS

  Although parents turn somewhat less strict in alcohol-specific rules over time, and adolescent alcohol use increases over time, the specific rules parents set remain important in restraining the alcohol use of their adolescent offspring. Thus, parents should and can feel confident about their parenting capabilities, and they should maintain being strict to prevent their offspring from drinking.

Results of the 'in control: no alcohol!' pilot study

More than 50% of Dutch 12-year olds already started drinking. Since it is known that delaying the onset of alcohol use results in a lower risk of alcohol-related problems, the recently developed 'In control: No alcohol!' prevention program is targeted at elementary school children and their mothers. In this pilot study, the success of program implementation and impact of the program on quality of alcohol-specific communication, rules and monitoring were evaluated, using a randomized controlled design. A total of 108 children (11-12 years) and their mothers participated in the prevention program, while the control group consisted of 105 dyads. Families participating in the experimental condition showed an increase in frequency of alcohol-specific communication and 75% of the dyads reported that they took part in at least 3 of 5 magazines, suggesting implementation was successful. The program led to an increase in quality of communication but only for those dyads in which mothers' alcohol use was above average. The program led parents to set up a non-drinking contract with their children and to monitor their children more closely. Results are promising but need to be replicated in a larger longitudinal study.

Catechol-O-methyltransferase Val158 Met genotype, parenting practices and adolescent alcohol use: testing the differential susceptibility hypothesis

BACKGROUND

  Recently, first evidence has been reported for a gene-parenting interaction (G × E) with regard to adolescent alcohol use. The present investigation set out to extend this research using the catechol-O-methyltransferase (COMT) Val(158) Met polymorphism as a genetic susceptibility factor. Moreover, the current study examined whether a potential G×E would be consistent with one of two models of gene-environment interplay (genetic vulnerability vs. differential susceptibility).

METHODS

  Data were collected as part of an ongoing epidemiological cohort study following the outcome of early risk factors from birth into adulthood. Two hundred and eighty-five participants (130 males, 155 females) were genotyped for the COMT Val(158) Met polymorphism and were administered an alcohol interview, providing measures of current frequency and amount of drinking at ages 15 and 19 years. Information on three dimensions of perceived parenting behavior was obtained from the 15-year-olds.

RESULTS

  Adolescents homozygous for the Met allele showed higher drinking activity at age 19 years when their parents had engaged in less supervision or were less involved, while their drinking activity was reduced under conditions of favorable parenting. No such relationship was found in individuals carrying the Val allele.

CONCLUSIONS

  The present findings correspond with the pattern of results predicted by the differential susceptibility hypothesis, suggesting that environmental variation would have a greater impact in individuals carrying a genetic susceptibility such that, in this group, exposure to negative environmental conditions would result in more adverse outcomes and the experience of favorable conditions would lead to more positive outcomes.

The moderating role of working memory capacity and alcohol-specific rule-setting on the relation between approach tendencies and alcohol use in young adolescents

BACKGROUND

Dual process models of alcohol addiction propose that the transition from normative alcohol consumption to heavy drinking is the result of an imbalance in interplay between relatively impulsive or automatic and reflective or controlled processes. The current study examines whether impulsive and reflective processes are also detectable in a sample of adolescents with limited alcohol use.

METHODS

Specifically, we tested the interaction between alcohol approach tendencies and 2 types of reflective processes, working memory capacity (WMC) and alcohol-specific rule-setting, on changes in alcohol use of 238 young adolescents (mean age: 13.82 years). Gender differences in these associations were also explored.

RESULTS

Results showed that WMC did not moderate the relation between approach tendencies and subsequent alcohol use, whereas rule-setting did, with stronger associations between approach tendencies and alcohol use for male adolescents reporting more permissive parents than male adolescents with parents enforcing stricter rules involving alcohol use. Associations between approach tendencies and subsequent alcohol use did not emerge for female adolescents.

CONCLUSIONS

Results indicate that even in a sample of adolescents with limited drinking experience, automatic processes are positively associated with alcohol use for male adolescents that are not motivated by parents to control their drinking.

Strategies for characterizing complex phenotypes and environments: general and specific family environmental predictors of young adult tobacco dependence, alcohol use disorder, and co-occurring problems

BACKGROUND

Defining phenotypes in studies of tobacco and alcohol misuse is difficult because of the complexity of these behaviors and their strong association with each other and with other problem behaviors. The present paper suggests a strategy for addressing this issue by conceptualizing and partitioning variance in phenotypes into either general or substance/behavior-specific. The paper also applies the general or substance/behavior-specific conceptualization to environmental predictors of tobacco and alcohol misuse and other problem behaviors.

METHODS

Data were drawn from the Seattle Social Development Project, a contemporary, ethnically diverse and gender-balanced longitudinal panel including 808 participants. Latent variable modeling was used to partition variance in young adult (age 24) nicotine dependence, alcohol abuse and dependence, illicit drug abuse and dependence, involvement in crime, and engagement in HIV sexual risk behavior into general problem behavior and behavior-specific variance. Similarly, measures of general, drinking-specific, and smoking-specific adolescent family environment were constructed.

RESULTS

Consistent with expectations, more positive general family environment during adolescence was associated with lower levels of shared variance in problem behaviors at age 24, but not with unique variance in tobacco or alcohol use disorder. Higher levels of family smoking and drinking environments during adolescence, however, were positively associated with unique variance in tobacco and alcohol use disorder, respectively, but did not predict shared variance in problem behaviors.

CONCLUSIONS

Results support the utility of the proposed approach. Ways in which this approach might contribute to future molecular genetic studies are discussed.

Substance use and exercise participation among young adults: parallel trajectories in a national cohort-sequential study

AIMS

This study examined the extent to which the trajectory of participation in sports, athletics or exercising (PSAE) covaried with substance use in early adulthood controlling for team sports participation using parallel process latent growth curve modeling.

DESIGN, SETTING AND PARTICIPANTS

Analysis of data collected from a series of panel studies using a cohort-sequential design. Specifically, the analyses used longitudinal data from 11 741 individuals from the graduating classes of 1986-2001, first surveyed as seniors in American high schools. Up to four additional follow-up surveys were administered to age 26 years. Data were collected using in-school and mailed self-administered questionnaires.

MEASUREMENTS

Level of PSAE, past-30-day alcohol, cigarette and marijuana use frequency and any past-30-day use of illicit drugs other than marijuana (IOTM) were the main processes of interest. Self-reported race/ethnicity, college status at age 19/20 years, parental education, gender and team sports participation during high school were included as covariates.

FINDINGS

Results indicate that higher initial levels of PSAE related to lower initial substance use prevalence rates other than alcohol, and lower initial prevalence rates of substance use then corresponded with lower substance use rates throughout early adulthood. Further, as individuals increased PSAE levels throughout early adulthood, the frequency of their use of cigarettes, marijuana and IOTM correspondingly decreased.

CONCLUSIONS

Increased participation in sports, athletics or exercising (PSAE) is related to significantly lower substance use frequency at modal age 18 and through significantly and negatively correlated growth trajectories through early adulthood. Encouraging PSAE among adolescents and early adults may relate to lower substance use levels throughout early adulthood.

The influence of gene-environment interactions on alcohol consumption and alcohol use disorders: a comprehensive review

Since 2005, a rapidly expanding literature has evaluated whether environmental factors such as socio-cultural context and adversity interact with genetic influences on drinking behaviors. This article critically reviews empirical research on alcohol-related genotype-environment interactions (GxE) and provides a contextual framework for understanding how genetic factors combine with (or are shaped by) environmental factors to influence the development of drinking behaviors and alcohol use disorders. Collectively, evidence from twin, adoption, and molecular genetic studies indicates that the degree of importance of genetic influences on risk for drinking outcomes can vary in different populations and under different environmental circumstances. However, methodological limitations and lack of consistent replications in this literature make it difficult to draw firm conclusions regarding the nature and effect size of alcohol-related GxE. On the basis of this review, we describe several methodological challenges as they relate to current research on GxE in drinking behaviors and provide recommendations to aid future research.

Genes, environment, and individual differences in responding to treatment for depression

A principal weakness of evidence-based psychiatry is that it does not account for the individual variability in therapeutic response among individuals with the same diagnosis. The aim of personalized psychiatry is to remediate this shortcoming and to use predictors to select treatment that is most likely to be beneficial for an individual. This article reviews the evidence that genetic variation, environmental exposures, and gene-environment interactions shape mental illness and influence treatment outcomes, with a primary focus on depression. Several genetic polymorphisms have been identified that influence the outcome of specific treatments, but the strength and generalizability of such influences are not sufficient to justify personalized prescribing. Environmental exposures in early life, such as childhood maltreatment, exert long-lasting influences that are moderated by inherited genetic variation and mediated through stable epigenetic mechanisms such as tissue- and gene-specific DNA methylation. Pharmacological and psychological treatments act on and against the background of genetic disposition, with epigenetic annotation resulting from previous experiences. Research in animal models suggests the possibility that epigenetic interventions may modify the impact of environmental stressors on mental health. Gaps in evidence are identified that need to be bridged before knowledge about cause can inform cure in personalized psychiatry.

DRD2 and DRD4 in relation to regular alcohol and cannabis use among adolescents: does parenting modify the impact of genetic vulnerability? The TRAILS study

AIMS

The aims of the present study were to determine the direct effect of DRD2 and DRD4, as well as their interaction with parenting (i.e. rejection, overprotection and emotional warmth), on the development of regular alcohol and cannabis use in 1192 Dutch adolescents from the general population.

METHODS

Information was obtained by self-report questionnaires. Perceived rejection, overprotection and emotional warmth were assessed at age 10-12. Regular alcohol and cannabis use were determined at age 15-18 and defined as the consumption of alcohol on 10 or more occasions in the past four weeks, and the use of cannabis on 4 or more occasions in the past four weeks. Models were adjusted for age, sex, parental alcohol or cannabis use, and externalizing behavior.

RESULTS

Carrying the A1 allele of the DRD2 TaqIA polymorphism, or the 7 repeat DRD4, was not directly related to regular alcohol or cannabis use. In addition, adolescent carriers of these genetic risk markers were not more susceptible to the influence of less optimal parenting. Main effects for parenting indicated that overprotection increased the risk of regular alcohol use, whereas the risk of cannabis use was enhanced by parental rejection and buffered by emotional warmth.

CONCLUSIONS

Our findings do not support an association between DRD2/DRD4 and regular alcohol and cannabis use in adolescents. Given the substance-specific influences of rejection, overprotection and emotional warmth, these parenting factors might be promising candidates for prevention work.

Risky alcohol use in adolescence: the role of genetics (DRD2, SLC6A4) and coping motives

BACKGROUND

Drinking to cope (i.e., drinking to forget or alleviate negative feelings) has been found to be associated with adolescents' heavy drinking and alcohol-related problems. Additionally, it is widely accepted that genetic factors are involved in alcohol use and dependence. Studies are only beginning to reveal, however, which specific genotypes are related to drinking behaviors, and it is unknown whether they may interact with coping motives in predicting adolescents' risky drinking. The aim of this study was to examine relationships between the dopamine D2 receptor gene (DRD2) Taq1A polymorphism (rs1800497), a serotonin transporter gene (SLC6A4) polymorphism (5-HTTLPR), coping motives, and adolescents' binge drinking and alcohol-related problems.

METHODS

Participants in this cross-sectional study were 282 Dutch adolescents (mean age 17.4, 47% men) who had consumed alcohol at least once in their life.

RESULTS

Coping motives were positively related to both binge drinking and alcohol-related problems, while DRD2 and SLC6A4 genotypes were not. DRD2, but not the SLC6A4 genotype, interacted with coping motives. The link between coping motives and alcohol outcomes was stronger among those carrying the DRD2 risk (A1) allele.

CONCLUSIONS

This study extends the present literature by providing additional insight into the etiological factors of adolescent drinking behavior. An interaction between a vulnerability gene (DRD2) and a cognitive factor (coping drinking) was found to be related to adolescents' binge drinking and alcohol-related problems.

H2 haplotype at chromosome 17q21.31 protects against childhood sexual abuse-associated risk for alcohol consumption and dependence

Animal research supports a central role for corticotropin-releasing factor (CRF) in actions of ethanol on brain function. An examination of alcohol consumption in adolescents reported a significant genotype x environment (G x E) interaction involving rs1876831, a corticotropin-releasing hormone receptor 1 (CRHR1) polymorphism, and negative events. CRHR1 and at least four other genes are located at 17q21.31 in an extremely large block of high linkage disequilibrium resulting from a local chromosomal inversion; the minor allele of rs1876831 is contained within the H2 haplotype. Here, we examine whether G x E interactions involving this haplotype and childhood sexual abuse (CSA) are associated with risk for alcohol consumption and dependence in Australian participants (n = 1128 respondents from 476 families) of the Nicotine Addiction Genetics project. Telephone interviews provided data on DSM-IV alcohol dependence diagnosis and CSA and enabled calculation of lifetime alcohol consumption factor score (ACFS) from four indices of alcohol consumption. Individuals reporting a history of CSA had significantly higher ACFS and increased risk for alcohol dependence. A significant G x E interaction was found for ACFS involving the H2 haplotype and CSA (P < 0.017). A similar G x E interaction was associated with protective effects against alcohol dependence risk (odds ratio 0.42; 95% confidence interval 0.20-0.89). For each outcome, no significant CSA-associated risk was observed in H2 haplotype carriers. These findings support conducting further investigation of the H2 haplotype to determine the gene(s) responsible. Our results also suggest that severe early trauma may prove to be an important clinical covariate in the treatment of alcohol dependence.

Gene-environment interactions and alcohol use and dependence: current status and future challenges

AIM

To discuss the current status of gene-environment interaction research with regard to alcohol use and dependence. Further, we highlight the difficulties concerning gene-environment studies.

METHODS

Overview of the current evidence for gene-environment interactions in alcohol outcomes, and of the associated challenges in gene-environment studies.

RESULTS

Attention to the causative roles of gene-environment interactions in alcohol use and dependence is increasing. Studies with twin designs are beginning to examine gene-shared environment effects, and animal studies have investigated gene-environment interaction effects on alcohol intake in primates. Thirteen studies incorporated gene-environment interactions in examining alcohol use or dependence in humans. These studies held a variety of candidate genes and environmental risk factors and their heterogeneity made it impossible to draw firm general conclusions.

CONCLUSIONS

Challenges for future gene-environment studies are abundant, and consist of, for example, the development of clear theoretical assumptions about neurobiological mechanisms and the recruitment of large longitudinal samples that already start in childhood. Replication is essential to prevent an overload of false-positive results. Despite the difficulties, it is crucial to include gene-environment interactions in future studies in order to unravel the aetiological factors of human alcohol outcomes.