Temperament and externalizing behavior as mediators of genetic risk on adolescent substance use

Pathways to substance use: Examining conduct problems and parenting behaviors from preschool to adolescence

While many studies have identified risk and protective factors of substance use (SU), few have assessed the reciprocal associations of child conduct problems (CP) and parenting practices and behaviors in the prediction of SU across development. A greater understanding of how these factors relate over time is needed to improve the timing of targeted prevention efforts. This study examined how child CP, parenting behaviors, and parents' own antisocial behavior relate from preschool to adolescence and eventuate in SU. Participants included 706 youth (70.6% male; 89.7% white) enrolled in the Michigan Longitudinal Study. Data from waves 1 (ages 3-5), 2 (ages 6-8), 3 (ages 9-11), 4 (ages 12-14), and 5 (ages 15-17) were included. A random intercept cross-lagged panel model (RI-CLPM) examined reciprocal associations between parenting practices, parents' antisocial behavior, and child CP over time (waves 1-4) and how these factors contribute to adolescent alcohol, cigarette, and marijuana use (wave 5). At the within-person level, negative parenting and parents' own antisocial behavior had a strong influence in late childhood/early adolescence. Only child CP emerged as a significant predictor of SU. Results highlight the importance of early intervention and the potential influence of parenting and child factors throughout development in the prevention of SU.

Developmental genetic effects on externalizing behavior and alcohol use: Examination across two longitudinal samples

Externalizing behavior in early adolescence is associated with alcohol use in adolescence and early adulthood and these behaviors often emerge as part of a developmental sequence. This pattern can be the result of heterotypic continuity, in which different behaviors emerge over time based on an underlying shared etiology. In particular, there is largely a shared genetic etiology underlying externalizing and substance use behaviors. We examined whether polygenic risk for alcohol use disorder predicted (1) externalizing behavior in early adolescence and alcohol use in adolescence in the Early Steps Multisite sample and (2) externalizing behavior in adolescence and alcohol use in early adulthood in the Project Alliance 1 (PAL1) sample. We examined associations separately for African Americans and European Americans. When examining European Americans in the Early Steps sample, greater polygenic risk was associated with externalizing behavior in early adolescence. In European Americans in PAL1, we found greater polygenic risk was associated with alcohol use in early adulthood. Effects were largely absent in African Americans in both samples. Results imply that genetic predisposition for alcohol use disorder may increase risk for externalizing and alcohol use as these behaviors emerge developmentally.

The role of parenting in developmental trajectories of risk for adolescent substance use: a bioecological systems cascade model

Parenting is a key influence and prevention target for adolescent substance use, and changes dramatically in form and function during adolescence. This theoretical synthesis reviews evidence of associations of substance use-specific parenting behaviors, dimensions, and styles with adolescent substance use, and integrates key developmental and family theories (e.g., bioecological, dynamical systems, family systems, developmental cascades) and methodological-conceptual advances to illustrate the complex role that parenting plays for the development of adolescent substance use in combination with child and contextual influences. The resulting bioecological systems cascade model centers the dynamic co-development of parenting and child influences in developmental cascades that lead to more or less risk for adolescent substance use. These trajectories are initiated by intergenerational influences, including genetics, parents' familial environments, and child-parent attachment. Culture and context influences are a holistic backdrop shaping parent-adolescent trajectories. Parenting is influences are conceptualized as a complex process by which specific parenting behaviors are informed by and accumulate into parenting dimensions which together comprise general parenting styles and are informed by the broader family context. The co-development of parenting and child biobehavioral risk is shaped by both parents and children, including by the genetics and environments they do and do not share. This co-development is dynamic, and developmental transitions of individuals and the family lead to periods of increased lability or variability that can change the longer-term trajectories of children's risk for substance use. Methodological avenues for future studies to operationalize the model are discussed.

Coping strategies as mediating mechanisms between adolescent polysubstance use classes and adult alcohol and substance use disorders

Adolescent polysubstance use is a robust predictor of substance use in adulthood and can be exacerbated by poor coping with stress over time. We examined whether latent classes of adolescents' polysubstance use predicted alcohol use disorder and substance use disorder diagnoses in adulthood via multiple stress coping strategies. Self-reported frequency of past 3-month alcohol, tobacco, and marijuana use in 792 adolescents (aged 16/17) were used to form latent classes of polysubstance use. Self-reported aggressive, reactive, substance use and cognitive coping strategies (ages 18/19, 22/23, 23/24) were examined as multiple mediators of polysubstance use classes and alcohol use disorder and substance use disorder in adulthood (age 26/27) controlling for demographic covariates. Latent class analysis resulted in High, Experimental, and Low polysubstance use classes. Those in high and experimental polysubstance use classes, compared to those in the low polysubstance use class, had greater use of aggressive and reactive coping strategies, which respectively predicted greater substance use disorder and alcohol use disorder in adulthood. Across all comparisons (high vs low, experimental vs low, and high vs experimental), higher polysubstance use was associated with greater substance use coping, which predicted both alcohol and substance use disorder. Greater polysubstance use, even experimental use, in adolescence is a significant risk factor for developing alcohol use disorder and substance use disorder in adulthood and this occurs, in part, via maladaptive stress coping strategies.

Chronic pain and delinquency partially explain the effect of the DRD4 gene polymorphism on adult substance use

Background: The dopamine receptor D4 [DRD4] has been reported to be associated with substance use. Yet, the roles that health conditions and behaviors may play in such association are understudied.Objective: This longitudinal study investigated the potential mediation effects of chronic pain and delinquency in adolescence on the association between the DRD4 2-repeat allele and substance use in adulthood. Sex, witnessing violence, and experiencing violence were also examined as potential moderators for the mediation pathways.Methods: We used the restricted and candidate gene data from the National Longitudinal Study of Adolescent to Adult Health (Waves I-IV) to conduct secondary analysis (N = 8,671; 47% male). A two-step approach was adopted to examine the mediation effects regarding four substance use outcomes in adulthood: number of lifetime alcohol use disorder symptoms, lifetime regular smoker status, past-month smoking, and lifetime "pain killer" misuse. The moderation effects were investigated using stratification and permutation.Results: The DRD4 2-repeat allele was associated with all adulthood substance use outcomes through adolescent chronic pain and delinquency (AORs/IRR range 1.08-3.78; all ps<0.01). The association between delinquency and smoking was higher among females. The association between delinquency and substance use was lower among the participants who witnessed violence in adolescence.Conclusions: This study identified modifiable mediators underlying the association between the DRD4 2-repeat allele and substance use behaviors, concluding that chronic pain and delinquency partially explain the effect of the DRD4 gene polymorphism on adult substance use.

α6-Containing GABAA Receptors: Functional Roles and Therapeutic Potentials

GABAA receptors containing the α6 subunit are highly expressed in cerebellar granule cells and less abundantly in many other neuronal and peripheral tissues. Here, we for the first time summarize their importance for the functions of the cerebellum and the nervous system. The cerebellum is not only involved in motor control but also in cognitive, emotional, and social behaviors. α6βγ2 GABAA receptors located at cerebellar Golgi cell/granule cell synapses enhance the precision of inputs required for cerebellar timing of motor activity and are thus involved in cognitive processing and adequate responses to our environment. Extrasynaptic α6βδ GABAA receptors regulate the amount of information entering the cerebellum by their tonic inhibition of granule cells, and their optimal functioning enhances input filtering or contrast. The complex roles of the cerebellum in multiple brain functions can be compromised by genetic or neurodevelopmental causes that lead to a hypofunction of cerebellar α6-containing GABAA receptors. Animal models mimicking neuropsychiatric phenotypes suggest that compounds selectively activating or positively modulating cerebellar α6-containing GABAA receptors can alleviate essential tremor and motor disturbances in Angelman and Down syndrome as well as impaired prepulse inhibition in neuropsychiatric disorders and reduce migraine and trigeminal-related pain via α6-containing GABAA receptors in trigeminal ganglia. Genetic studies in humans suggest an association of the human GABAA receptor α6 subunit gene with stress-associated disorders. Animal studies support this conclusion. Neuroimaging and post-mortem studies in humans further support an involvement of α6-containing GABAA receptors in various neuropsychiatric disorders, pointing to a broad therapeutic potential of drugs modulating α6-containing GABAA receptors. SIGNIFICANCE STATEMENT: α6-Containing GABAA receptors are abundantly expressed in cerebellar granule cells, but their pathophysiological roles are widely unknown, and they are thus out of the mainstream of GABAA receptor research. Anatomical and electrophysiological evidence indicates that these receptors have a crucial function in neuronal circuits of the cerebellum and the nervous system, and experimental, genetic, post-mortem, and pharmacological studies indicate that selective modulation of these receptors offers therapeutic prospects for a variety of neuropsychiatric disorders and for stress and its consequences.

The externalizing and internalizing pathways to marijuana use initiation: Examining the synergistic effects of impulsiveness and sensation seeking

Adolescent marijuana use has become increasingly more problematic compared with the past; thus, understanding developmental processes that increase the liability of marijuana use is essential. Two developmental pathways to adolescent substance use have been proposed: an externalizing pathway that emphasizes the expression of aggressive and delinquent behavior, and an internalizing pathway that emphasizes the role of depressive symptoms and negative affect. In this study, we aimed to examine the synergistic role of impulsiveness and sensation seeking in the two risk pathways to determine whether both high and low levels of the traits are risk factors for marijuana use. Our study included 343 adolescents (52% were girls, 78% identified as Hispanic) that oversampled high-risk youth (78% had a family history of substance use disorder), assessed biannually between the ages of 13-16 years old. Moderated mediation analyses revealed that high levels of sensation seeking indirectly predicted marijuana use through higher mean levels of externalizing behavior. The positive relationship between sensation seeking and externalizing behavior was only significant at high levels of impulsiveness. Conversely, low levels of sensation seeking indirectly predicted marijuana use through higher mean levels of internalizing behavior. The negative relationship between sensation seeking and internalizing behavior was only significant at low levels of impulsiveness. Collectively, these results demonstrate that high and low levels of both impulsiveness and sensation seeking confer increased risk of marijuana use, albeit through different mechanisms. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Temperament and character traits in substance use disorder in Iran: a case control study

Background

Patients with Substance use disorder have distinct personality traits, they were high score in novelty seeking (NS) and sensation seeking and lower in Self-directedness and higher in Self-transcendence, so we aim to investigate the relationships of temperament and characteristics with related some variables such as substance of choice.

Design and setting

A case–control study enrolling 70 Substance use disorder patients and 70 controls was conducted at Mashhad University of medical sciences.

Methods

Using a case–control design, a group of 70 Substance use disorder patients and 70 controls was conducted at Mashhad university of medical sciences. All participation completed the 240 questions of Temperament and Character Inventory-Revised (TCI-R). Multivariate analysis of covariance (MANCOVA) was employed to compare the relationship between temperament and character traits and patterns of substance use.

Results

The scores of reward dependence, persistence, self-directedness, cooperativeness, and self-transcendence were significantly lower in the case group compared to healthy individuals (P < 0.05). In contrast, the score of novel seeking was significantly higher in the case group (P < 0.05). On the other hand, harm avoidance was not significantly different between the two studied groups (P = 0.637).

Conclusions

Higher NS in patients with substance use disorder is common and different traits, and temperaments would choose different substance combinations.

Developmental Cascades from Polygenic and Prenatal Substance Use to Adolescent Substance Use: Leveraging Severity and Directionality of Externalizing and Internalizing Problems to Understand Pubertal and Harsh Discipline-Related Risk

The current study leveraged the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort (n = 4504 White boys, n = 4287 White girls assessed from the prenatal period through 18.5 years of age) to test a developmental cascade from genetic and prenatal substance use through pubertal timing and parenting to the severity of (regardless of type) and directionality (i.e., differentiation) of externalizing and internalizing problems to adolescent substance use. Limited associations of early pubertal timing with substance use outcomes were only observable via symptom directionality, differently for girls and boys. For boys, more severe exposure to prenatal substance use influenced adolescent substance use progression via differentiation towards relatively more pure externalizing problems, but in girls the associations were largely direct. Severity and especially directionality (i.e., differentiation towards relatively more pure externalizing problems) were key intermediaries in developmental cascades from parental harsh discipline with substance use progressions for girls and boys.

Substance Use Outcomes from Two Formats of a Cognitive-Behavioral Intervention for Aggressive Children: Moderating Roles of Inhibitory Control and Intervention Engagement

Although cognitive-behavioral interventions have reduced the risk of substance use, little is known about moderating factors in children with disruptive behaviors. This study examined whether aggressive preadolescents’ inhibitory control and intervention engagement moderates the effect of group versus individual delivery on their substance use. Following screening for aggression in 4th grade, 360 children were randomly assigned to receive the Coping Power intervention in either group or individual formats. The sample was primarily African American (78%) and male (65%). Assessments were made of children’s self-reported substance use from preintervention through a six-year follow-up after intervention, parent-reported inhibitory control at preintervention, and observed behavioral engagement in the group intervention. Multilevel growth modeling found lower increases in substance use slopes for children with low inhibitory control receiving individual intervention, and for children with higher inhibitory control receiving group intervention. Children with low inhibitory control but who displayed more positive behavioral engagement in the group sessions had slower increases in their substance use than did similar children without positive engagement. Aggressive children’s level of inhibitory control can lead to tailoring of group versus individual delivery of intervention. Children’s positive behavioral engagement in group sessions is a protective factor for children with low inhibitory control.

Effects of an Alcohol-Related Harm Prevention Program among Out-of-School Female Adolescents

This study aimed to evaluate the effects of an alcohol-related harm prevention program on out-of-school adolescent girls. This was a quasi-experimental study employing a randomized controlled non-synchronized design. There were 23 and 22 participants in the experimental and control groups, respectively. The program comprised three sessions aiming to motivate voluntary changes and promote autonomous decision-making. The experimental group showed significantly higher alcohol-related knowledge and substantially lower alcohol outcome expectancy than the control group. No significant differences emerged from drinking refusal, self-efficacy, or alcohol abstinence intention. This program could improve alcohol-related knowledge and reduce out-of-school adolescent girls' positive alcohol outcome expectancy.

Implicit play or explicit cognitive behaviour therapy: The impact of intervention approaches to facilitate social skills development in adolescents

INTRODUCTION

Early adolescence is a time of increased social interaction with peers. Social competence is related to pretend play ability in younger children, but a lack of pretend play ability in childhood may also be associated with social challenges in early adolescence. Adolescents who find social situations challenging experience alienation from peers resulting in lowered self-regard. This paper presents an exploratory study comparing an Implicit group intervention (age-appropriate play based group (PB)) to an Explicit group intervention Cognitive Behavioural Therapy (CBT) to increase social ability in adolescents.

METHODS

Six adolescents, three female and three male, were in the Implicit group (PB; mean age 12.3 years, SD = 1.21). Six male adolescents were in the Explicit group (CBT; mean age 13.3 years, SD = 1.03). All participants were assessed pre- and post the 8-week intervention for social competence, cognitive flexibility and narrative ability. The Implicit group (PB) was assessed through an age appropriate play assessment. Seven participants had a formal diagnosis, including autism spectrum disorder, and all were in mainstream high schools.

RESULTS

The Explicit group (CBT) showed a medium effect for social engagement, total social skills, emotional engagement and a large effect for a decrease in flexible thinking. The Implicit group (PB) showed a large impact for narrative ability with increases in ability to sequence events, initiation and creation of plot, understanding character roles and total movie score, with medium effects for generation of problems, precise vocabulary and use of symbols. The Implicit group (PB) maintained cognitive flexibility, and decreased in social self-scoring which showed medium effects for externalising and internalising.

CONCLUSION

This paper contributes to evidence that the choice of social skills intervention impacts different skill sets. For neuro-diverse adolescents, the cognitive intervention impacted social and emotional engagement and the play-based intervention impacted a wider range of abilities related to narrative social interaction.

Exploring pathways to substance use: A longitudinal examination of adolescent sport involvement, aggression, and peer substance use

The relationship between adolescent sport involvement and later substance use (SU) has been unclear. Understanding the pathways through which sport involvement influences SU may help identify targets for prevention. Using a sample of 535 adolescents from the Michigan Longitudinal Study (MLS; 67.29% male, 78.13% European American), this study prospectively examined whether aggression during late adolescence mediated the association between sport involvement during early adolescence and alcohol, marijuana, and cigarette use during early adulthood. In addition, perceived peer SU during early adolescence was tested as a potential moderator in the association between sport involvement on SU. High sport involvement was associated with more alcohol use. In contrast, the indirect effect of sport involvement on SU via aggression was significant for cigarette use, and marginally significant for marijuana use. Lastly, peer SU was a significant moderator in the cigarette model, indicating low peer SU was somewhat protective among high sport-involved adolescents. Prevention targeting alcohol use and associated consequences, as well as aggressive behaviors may help address future substance use.

Childhood adversity, externalizing behavior, and substance use in adolescence: Mediating effects of anterior cingulate cortex activation during inhibitory errors

Childhood adversity can negatively impact development across various domains, including physical and mental health. Adverse childhood experiences have been linked to aggression and substance use; however, developmental pathways to explain these associations are not well characterized. Understanding early precursors to later problem behavior and substance use can inform preventive interventions. The aim of the current study was to examine neurobiological pathways through which childhood adversity may lead to early adolescent problem behavior and substance use in late adolescence by testing two prospective models. Our first model found that early adolescent externalizing behavior mediates the association between childhood adversity and alcohol, cigarette, and marijuana use in late adolescence. Our second model found that activation in the anterior cingulate cortex (ACC) during an inhibitory control task mediates the association between childhood adversity and early adolescent externalizing behavior, with lower ACC activation associated with higher levels of adversity and more externalizing behavior. Together these findings indicate that the path to substance use in late adolescence from childhood adversity may operate through lower functioning in the ACC related to inhibitory control and externalizing behavior. Early life stressors should be considered an integral component in the etiology and prevention of early and problematic substance use.

The link between bipolarity and substance use: A controlled clinic based study

OBJECTIVES

Because of high rates of co-occurrence, common familial risk, and phenotypic similarities, we conjectured that substance use and bipolar disorder might have a common substrate of origin in bipolarity and that they might lie on a continuum of bipolarity. Thus it was aimed to investigate the association between bipolarity and substance use through a controlled, clinic based study.

METHODS

Cross sectional assessment and comparison of bipolarity as trait in four groups, namely the substance use disorder (SUD), bipolar disorder (BPAD), dual diagnosis (DD), and the healthy control (HC) groups. Bipolar spectrum diagnostic scale (BSDS) was used. The quality of life in these four groups was also assessed using WHOQOL-Bref scale.

RESULTS

The mean Bipolar spectrum diagnostic scale (BSDS) score in SUD was 11.0 ± 5.3 which was more than that of HC (6.2 ± 3.9) and lesser than that in BPAD (18.4 ± 4.2) and DD (20.6 ± 3.6). Differences among all four groups were statistically significant. SUD group was found to have significantly higher score than healthy control. The BSDS score of DD and BPAD groups were higher than those of SUD but the difference between BPAD and DD was non-significant.

DISCUSSION

The results showed a potential association between substance dependence and bipolarity. Mood dysregulation appears to be the link between the two. The gradient of bipolarity detected by BSDS screener suggests a continuum model between substance use and bipolar disorder. However, this is a clinic based study and only male patients have been taken for study.

Developmental Pathways from Genetic, Prenatal, Parenting and Emotional/Behavioral Risk to Cortisol Reactivity and Adolescent Substance Use: A TRAILS Study

Cortisol reactivity is a frequently studied biomarker of substance use, though infrequently examined in adolescence. However, past research provides evidence that multiple developmental influences, including genetics and both prenatal and postnatal environmental influences, contribute both to cortisol reactivity and adolescent substance use. The aim of this study was to assess the impact of these earlier developmental influences on cortisol reactivity to a social stress challenge and adolescent substance use (smoking, alcohol, and marijuana use frequency assessed at age 16 years), using data from the TRacking Adolescents' Individual Lives Survey (TRAILS; N= 2230 adolescents, 51% female). Developmental pathways included polygenic risk, prenatal stress, warm parenting (age 11), and internalizing and externalizing problems (intercepts and change from 11-16 years). Cortisol reactivity was associated with smoking but not alcohol or marijuana use. Externalizing problems were the stronger predictor of adolescent substance use, but internalizing problems also had an important role. Prenatal stress and middle childhood parenting operated via middle childhood externalizing problems, and parenting also operated via trajectories of growth of externalizing problems in predicting adolescent substance use outcomes. Further, there were protective effects of internalizing problems for alcohol and marijuana use in the context of a more comprehensive model. These developmental influences did not attenuate the association of cortisol reactivity and smoking. These findings suggest a need to understand the broader developmental context regarding the impact of internalizing pathways to substance use, and that it is unlikely that cortisol reactivity and smoking are associated solely because of common developmental influences.

The Impact of Genes on Adolescent Substance Use: A Developmental Perspective

Purpose

This review discusses the importance of understanding the impact of genetic factors on adolescent substance use within a developmental framework. Methods for identifying genetic factors, relevant endophenotypes and intermediate phenotypes, and gene-environment interplay effects will be reviewed.

Findings

Prior work supports the role of polygenic variation on adolescent substance use. Mechanisms through which genes impact adolescent phenotypes consist of differences in neural structure and function, early temperamental differences, and problem behavior. Gene-environment interactions are characterized by increased vulnerability to both maladaptive and adaptive contexts.

Summary

Developmental considerations in genetic investigations highlight the critical role that polygenic variation has on adolescent substance use. Yet, determining what to do with this information, especially in terms of personalized medicine, poses ethical and logistic challenges.

Parenting Practices and Adjustment Profiles among Latino Youth in Rural Areas of the United States

On average, Latino adolescents in the United States (U.S.) are at an elevated risk for developing internalizing symptoms, externalizing behaviors, and engaging in binge drinking. Latino youth in rural U.S. contexts may be particularly at risk. Parent–adolescent relationships may be associated with each of these indicators of maladjustment, as well as the co-occurrence of these issues. In the current study, adjustment profiles based on internalizing symptoms, externalizing behaviors, and binge drinking among 198 Latino adolescents (Mage = 15.90, SD = 1.47) living in rural areas of the United States were examined. Further, the association of adjustment profiles with parental behavioral involvement, parental monitoring, and familial ethnic socialization was tested. Four adjustment profiles emerged from a cluster analysis (i.e., low risk, internalizing risk, externalizing risk, co-occurring risk). Results indicated that adolescents in the co-occurring risk profile reported the lowest levels of parental monitoring compared to the other three profiles, lower familial ethnic socialization compared to the low risk and internalizing risk profiles, and lower parental behavioral involvement compared to the internalizing risk profile. The findings have implications for family-based, culturally informed interventions to encourage positive adjustment among Latino adolescents in rural areas of the United States.

Predicting Behavior Problems in Korean Preschoolers: Interactions of the SLC6A4 Gene and Maternal Negative Affectivity

Objective

This study aimed to investigate whether maternal negative affectivity (MNA) moderates the effect of genetic polymorphism of SLC6A4 on behavior problems in children.

Methods

Study participants comprised 143 preschoolers and their mothers from South Korea. The Childhood Behavior Checklist and Emotionality, Activity, and Sociability adult scale were used to measure child behavior and maternal affectivity. DNA from saliva was genotyped to determine serotonin transporter polymorphism.

Results

MNA appeared to exert effects in externalizing (b=5.78, p<0.001) and internalizing problems (b=6.09, p< 0.001). Interaction between SLCA4 polymorphism and MNA showed effects on externalizing (b=−7.62, p<0.01) and internalizing problems (b=−9.77, p<0.01). Children with two short alleles showed considerable differences in both externalizing and internalizing problems according to MNA; however, children with one short allele or none showed relatively few differences in behavior problems due to maternal affectivity.

Conclusion

The effect of SLC6A4 polymorphism on child behavior seemed to be moderated by MNA. In addition, the impact of MNA was found to vary based on a child’s genetic risk. High MNA may trigger the risk allele while low MNA causes the risk allele to illicit less behavior problems. Children with two short variants of the SLC6A4 gene may benefit from intervention that modulates MNA.

[Internalizing and externalizing behavior problems and substance use in adolescence]

This study investigated the relationship between externalizing behavior problems (EBP), internalizing behavior problems (IBP), and combined externalizing/internalizing behavior problems (EIBP) in early adolescence (11 years) and substance use (alcohol, tobacco, and illegal drugs) at 15 years, using data from the 1993 Pelotas (Brazil) birth cohort. Behavior problems were assessed with the Strengths and Difficulties Questionnaire (SDQ), applied to mothers when their children were 15 years old. Substance use was assessed with a self-applied confidential questionnaire for the adolescent. The association between behavior problems and substance use was analyzed with Poisson regression with robust adjustment of variance. After adjusting for confounding, adolescents with EBP showed higher risk of alcohol abuse (RR = 1.74, 95%CI: 1.21; 2.50) and experimentation (RR = 1.78, 95%CI: 1.42; 2,23) and tobacco use in the previous 30 days (RR = 2.38, 95%CI: 1.64; 3.45). Adolescents with IBP showed greater risk of having tried tobacco (RR = 1.54, 95%CI: 1.22; 1.93) and of having used tobacco products in the previous 30 days (RR = 1.92, 95%CI: 1.31; 2.83). Adolescents with EIBP showed greater risk of trying (RR = 2.24, 95%CI: 1.57; 3.21) and consuming tobacco products in the previous days (RR = 3.01, 95%CI: 1.63; 5.56), and lower risk of having tried alcohol at 15 years of age (RR = 0.72, 95%CI: 0.55; 0.94). Public health measures aimed at reducing behavior problems in early adolescence can help reduce tobacco and alcohol consumption at 15 years.

Pathways to Youth Behavior: The Role of Genetic, Neural, and Behavioral Markers

Neural and temperamental mechanisms through which a genetic risk marker in the γ-amino butyric acid α2 receptor subunit (GABRA2) impacts adolescent functioning were investigated. Participants (N = 80; 29 female) completed an emotional word task during functional magnetic resonance imaging. Behavioral control, negative emotionality, and resiliency temperament constructs were assessed. Externalizing and internalizing problems were the outcomes. Those with the GABRA2 minor allele had reduced activation to positive words in the angular gyrus, middle temporal gyrus, and cerebellum, and to negative words in frontal, parietal, and occipital cortices. Reduced activation in the angular gyrus predicted greater negative emotionality and, in turn, elevated externalizing problems. Reduced activation in the inferior parietal cortex predicted greater resiliency and, in turn, low externalizing problems.

Biological underpinnings of an internalizing pathway to alcohol, cigarette, and marijuana use

There is a limited understanding as to how specific genes impact addiction risk. Applying a developmental framework and research domain criteria (RDoC) to identify etiological pathways from genetic markers to addiction may have utility. Prior research has largely focused on externalizing pathways to substance use. Although internalizing mechanisms have received less attention, there is strong support that addiction is a longer term consequence of using substances to cope with internalizing as well as externalizing problems. This study tests whether temperament and depression mediate the association between specific genetic variants and substance use. The sample consisted of 426 adolescents from the Michigan Longitudinal Study (70.9% boys, 84.0% White). Four specific genetic variants were examined: SLC6A4 (5HTTLPR), BDNF (rs6265), NPY (rs3037354), and CRHBP (rs7728378). Childhood resiliency and behavioral control were examined as potential mediators, in addition to early adolescent depression, using a multiple-mediator path model. Resiliency and depression were supported as mediators in the association between genetic risk and later substance use. Important differences emerged across substances of abuse. Indirect effects via depression were not significant with the inclusion of aggression. Early difficulties with emotional coping may represent nonspecific neurobiological underpinnings for an internalizing pathway to addiction. (PsycINFO Database Record

An endophenotype approach to the genetics of alcohol dependence: a genome wide association study of fast beta EEG in families of African ancestry

Fast beta (20-28 Hz) electroencephalogram (EEG) oscillatory activity may be a useful endophenotype for studying the genetics of disorders characterized by neural hyperexcitability, including substance use disorders (SUDs). However, the genetic underpinnings of fast beta EEG have not previously been studied in a population of African-American ancestry (AA). In a sample of 2382 AA individuals from 482 families drawn from the Collaborative Study on the Genetics of Alcoholism (COGA), we performed a genome-wide association study (GWAS) on resting-state fast beta EEG power. To further characterize our genetic findings, we examined the functional and clinical/behavioral significance of GWAS variants. Ten correlated single-nucleotide polymorphisms (SNPs) (r2>0.9) located in an intergenic region on chromosome 3q26 were associated with fast beta EEG power at P<5 × 10-8. The most significantly associated SNP, rs11720469 (β: -0.124; P<4.5 × 10-9), is also an expression quantitative trait locus for BCHE (butyrylcholinesterase), expressed in thalamus tissue. Four of the genome-wide SNPs were also associated with Diagnostic and Statistical Manual of Mental Disorders Alcohol Dependence in COGA AA families, and two (rs13093097, rs7428372) were replicated in an independent AA sample (Gelernter et al.). Analyses in the AA adolescent/young adult (offspring from COGA families) subsample indicated association of rs11720469 with heavy episodic drinking (frequency of consuming 5+ drinks within 24 h). Converging findings presented in this study provide support for the role of genetic variants within 3q26 in neural and behavioral disinhibition. These novel genetic findings highlight the importance of including AA populations in genetics research on SUDs and the utility of the endophenotype approach in enhancing our understanding of mechanisms underlying addiction susceptibility.

Variation in SWI/SNF Chromatin Remodeling Complex Proteins is Associated with Alcohol Dependence and Antisocial Behavior in Human Populations

BACKGROUND

Testing for direct gene or single nucleotide polymorphism replication of association across studies may not capture the true importance of a candidate locus; rather, we suggest that relevant replication across studies may be found at the level of a biological process. We previously observed that variation in 2 members of the switching defective/sucrose nonfermenting (SWI/SNF) chromatin remodeling complex is associated with alcohol dependence (AD) in the Irish Affected Sib Pair Study for Alcohol Dependence. Here, we tested for association with alcohol-related outcomes using a set of genes functioning in the SWI/SNF complex in 2 independent samples.

METHODS

We used a set-based analysis to examine the 29 genes of the SWI/SNF complex for evidence of association with (i) AD in the adult Collaborative Study on the Genetics of Alcoholism (COGA) case-control sample and (ii) antisocial behavior, hypothesized to be a genetically related developmental precursor, in a younger population sample (Spit for Science [S4S]).

RESULTS

We found evidence for association of the SWI/SNF complex with AD in COGA (p = 0.0435) and more general antisocial behavior in S4S (p = 0.00026). The genes that contributed most strongly to the signal in COGA were SS18L1, SMARCD1, BRD7, BCL7B, SMARCB1, and BCL11A. In the S4S sample, ACTB, ARID2, BCL11A, BCL11B, BCL7B, BCL7C, DPF2, and DPF3 all contributed strongly to the signal.

CONCLUSIONS

We detected associations between the SWI/SNF complex and AD in an adult population selected from treatment-seeking probands and antisocial behavior in an adolescent population sample. This provides strong support for a role for SWI/SNF in the development of alcohol-related problems.

National Trends in Substance Use and Use Disorders Among Youth

OBJECTIVE

To examine trends in the 12-month prevalence of patterns of substance use and substance use disorders (SUDs) among US youth during 2002 through 2014.

METHOD

Data were from 288,300 persons 12 to 17 years old who participated in the 2002 to 2014 National Surveys on Drug Use and Health. Descriptive analyses and bivariable and multivariable logistic regressions were applied.

RESULTS

During 2002 through 2014, among US youth, the 12-month prevalence of any substance use decreased by 27.1% (from 43.2% to 31.5%); among youth users, the 12-month prevalence of SUDs decreased by 28.9% (from 27.0% to 19.2%), and the ratio of substance dependence to abuse decreased from 2.2 to 1.6. Multiple substance use was common and was associated with SUDs. During 2002 through 2014, the prevalence of using marijuana and alcohol only, using marijuana only, and having marijuana use disorders only increased, whereas most other trends were downward. Increases in age at first substance use were associated with downward trends in any substance use. Upward trends in age at first substance use, youth and parental strong disapproval of cigarette use, and youths' seatbelt-wearing prevalence and downward trends in substance use patterns were associated with the downward trend in SUDs among youth users.

CONCLUSION

The 12-month prevalence of any substance use among youth and SUDs among youth users decreased during 2002 through 2014. Postponing age at first use of any substance is critical among youth in the United States. Future research is needed to better understand the interrelations between specific risk and protective factors, age at first substance use, substance use patterns, and SUDs among youth users.

Serotonin functioning and adolescents' alcohol use: A genetically informed study examining mechanisms of risk

The current study used data from two longitudinal samples to test whether self-regulation, depressive symptoms, and aggression/antisociality were mediators in the relation between a polygenic score indexing serotonin (5-HT) functioning and alcohol use in adolescence. The results from an independent genome-wide association study of 5-hydroxyindoleacetic acid in the cerebrospinal fluid were used to create 5-HT polygenic risk scores. Adolescents and/or parents reported on adolescents' self-regulation (Time 1), depressive symptoms (Time 2), aggression/antisociality (Time 2), and alcohol use (Time 3). The results showed that 5-HT polygenic risk did not predict self-regulation. However, adolescents with higher levels of 5-HT polygenic risk showed greater depression and aggression/antisociality. Adolescents' aggression/antisociality mediated the relation between 5-HT polygenic risk and later alcohol use. Deficits in self-regulation also predicted depression and aggression/antisociality, and indirectly predicted alcohol use through aggression/antisociality. Pathways to alcohol use were especially salient for males from families with low parental education in one of the two samples. The results provide insights into the longitudinal mechanisms underlying the relation between 5-HT functioning and alcohol use (i.e., earlier aggression/antisociality). There was no evidence that genetically based variation in 5-HT functioning predisposed individuals to deficits in self-regulation. Genetically based variation in 5-HT functioning and self-regulation might be separate, transdiagnostic risk factors for several types of psychopathology.

A genome wide association study of fast beta EEG in families of European ancestry

BACKGROUND

Differences in fast beta (20-28Hz) electroencephalogram (EEG) oscillatory activity distinguish some individuals with psychiatric and substance use disorders, suggesting that it may be a useful endophenotype for studying the genetics of disorders characterized by neural hyper-excitability. Despite the high heritability estimates provided by twin and family studies, there have been relatively few genetic studies of beta EEG, and to date only one genetic association finding has replicated (i.e., GABRA2).

METHOD

In a sample of 1564 individuals from 117 families of European Ancestry (EA) drawn from the Collaborative Study on the Genetics of Alcoholism (COGA), we performed a Genome-Wide Association Study (GWAS) on resting-state fronto-central fast beta EEG power, adjusting regression models for family relatedness, age, sex, and ancestry. To further characterize genetic findings, we examined the functional and behavioral significance of GWAS findings.

RESULTS

Three intronic variants located within DSE (dermatan sulfate epimerase) on 6q22 were associated with fast beta EEG at a genome wide significant level (p<5×10-8). The most significant SNP was rs2252790 (p<2.6×10-8; MAF=0.36; β=0.135). rs2252790 is an eQTL for ROS1 expressed most robustly in the temporal cortex (p=1.2×10-6) and for DSE/TSPYL4 expressed most robustly in the hippocampus (p=7.3×10-4; β=0.29). Previous studies have indicated that DSE is involved in a network of genes integral to membrane organization; gene-based tests indicated that several variants within this network (i.e., DSE, ZEB2, RND3, MCTP1, and CTBP2) were also associated with beta EEG (empirical p<0.05), and of these genes, ZEB2 and CTBP2 were associated with DSM-V Alcohol Use Disorder (AUD; empirical p<0.05).'

DISCUSSION

In this sample of EA families enriched for AUDs, fast beta EEG is associated with variants within DSE on 6q22; the most significant SNP influences the mRNA expression of DSE and ROS1 in hippocampus and temporal cortex, brain regions important for beta EEG activity. Gene-based tests suggest evidence of association with related genes, ZEB2, RND3, MCTP1, CTBP2, and beta EEG. Converging data from GWAS, gene expression, and gene-networks presented in this study provide support for the role of genetic variants within DSE and related genes in neural hyperexcitability, and has highlighted two potential candidate genes for AUD and/or related neurological conditions: ZEB2 and CTBP2. However, results must be replicated in large, independent samples.