Prospective effects of adolescent indicators of behavioral disinhibition on DSM-IV alcohol, tobacco, and illicit drug dependence in young adulthood

A Bivariate Twin Study of Lifetime cannabis Initiation and Lifetime Regular Tobacco Smoking Across Three Different Countries

Regular cigarette smoking and cannabis consumption are strongly positively related to each other, yet few studies explore their underlying variation and covariation. We evaluated the genetic and environmental decomposition of variance and covariance of these two traits in twin data from three countries with different social norms and legislation. Data from the Netherlands Twin Register, FinnTwin12/16, and the Minnesota Center for Twin Family Research (total N = 21,617) were analyzed in bivariate threshold models of lifetime regular smoking initiation (RSI) and lifetime cannabis initiation (CI). We ran unstratified models and models stratified by sex and country. Prevalence of RSI was lowest in the Netherlands and prevalence of CI was highest in Minnesota. In the unstratified model, genetic (A) and common environmental factors (C) contributed substantially to the liabilities of RSI (A = 0.47, C = 0.34) and CI (A = 0.28, C = 0.51). The two liabilities were significantly phenotypically (rP = 0.56), genetically (rA = 0.74), and environmentally correlated in the unstratified model (rC = 0.47and rE = 0.48, representing correlations between common and unique environmental factors). The magnitude of phenotypic correlation between liabilities varied by country but not sex (Minnesota rP ~ 0.70, Netherlands rP ~ 0.59, Finland rP ~ 0.45). Comparisons of decomposed correlations could not be reliably tested in the stratified models. The prevalence and association of RSI and CI vary by sex and country. These two behaviors are correlated because there is genetic and environmental overlap between their underlying latent liabilities. There is heterogeneity in the genetic architecture of these traits across country.

Subjective effects as predictors of substance use disorders in a clinical sample: A longitudinal study

BACKGROUND

The literature on the association between subjective effects (SEs; i.e., how an individual perceives their physiological and psychological reactions to a drug) and substance use disorders (SUDs) is largely limited to community samples. The present study addressed the following aims in a clinical sample: whether SEs predict general versus substance-specific SUD in adolescence and adulthood after controlling for conduct disorder symptoms (CDsymp); whether SEs predict SUDs across drug classes; whether SEs predict change in SUD from adolescence to adulthood; and whether there are racial/ethnic differences in associations.

METHODS

Longitudinal analyses were conducted using data from a sample of 744 clinical probands recruited from residential and outpatient SUD treatment facilities in CO during adolescence (Mage = 16.26) and re-assessed twice in adulthood (Mages = 22.56 and 28.96), approximately seven and twelve years after first assessment. SEs and CDsymp were assessed in adolescence. SUD severity was assessed at adolescence and twice during adulthood.

RESULTS

SEs assessed in adolescence robustly predicted general SUD for legal and illegal substances in adolescence and adulthood, whereas CDsymp predicted SUD primarily in adolescence. Higher positive and negative SEs in adolescence were associated with greater SUD severity after controlling for CDsymp, with similar magnitudes. Results indicated cross-substance effects of SEs on SUD. We found no evidence for racial/ethnic differences in associations.

CONCLUSIONS

We investigated the progression of SUD in a high-risk sample with greater odds of sustained SUD. In contrast to CDsymp, both positive and negative SEs consistently predicted general SUD across substances in adolescence and adulthood.

Temperament and character profiles of adolescent participants in the choking game

OBJECTIVE

The role of personality traits in self-asphyxial behaviors remains largely unexplored. The aim of this study was to explore temperament and character profiles of youth reporting participation in the choking game using Cloninger's biopsychosocial model of personality.

METHODS

Data were collected among French middle-school students (N=1771) aged 9-16 years (mean age=13.0, SD=1.3) and randomly selected from 13 public establishments located in different regions of France. Logistic regression models were run to identify Cloninger's temperamental and character dimensions associated with engagement in the choking game.

RESULTS

Descriptive analysis revealed that participants showed high scores of novelty-seeking (Cohen's d=0.293, p<0.001) and low levels of cooperativeness (Cohen's d=0.182, p<0.01), persistence (Cohen's d=0.182, p<0.05), and reward dependence (Cohen's d=0.241, p<0.01). However, multivariate modeling indicated that only the novelty-seeking dimension tended to slightly differentiate participants from non-participants within the global sample (OR=1.03, 95% CI: 1-1.06). When we compared girls and boys, we found a slight trend in association only in boys (OR=1.04, 95% CI: 1-1.08).

CONCLUSIONS

Our study, which contributes to the growing literature on the psychological correlates of choking activities and is the first to investigate the potential predictive role of personality traits in this risky behavior, suggests to some extent that (a) the choking game could possibly be influenced by some temperamental characteristics, and that (b) it might not have the same function according to the gender considered.

Electrophysiological Evidence of Enhanced Processing of Novel Pornographic Images in Individuals With Tendencies Toward Problematic Internet Pornography Use

Novelty seeking is regarded as a core feature in substance use disorders. However, few studies thus far have investigated this feature in problematic Internet pornography use (PIPU). The main aim of the present study was to examine group differences in electrophysiological activity associated with novelty processing in participants with high tendencies toward PIPU vs. low tendencies using event-related potentials (ERPs). Twenty-seven participants with high tendencies toward PIPU and 25 with low tendencies toward PIPU completed a modified three-stimulus oddball task while electroencephalogram (EEG) was recorded. Participants were instructed to detect neutral target stimuli from distracting stimuli. The distracting stimuli contained a familiar sexual stimulus and a set of novel sexual stimuli. The novel-familiar difference waves were calculated to identify specific group difference in novelty effect. While both groups demonstrated a sustained novelty effect in the late positive potential (LPP) within the 500–800 ms time windows, the novelty effect was greater in the high tendencies toward PIPU group than in the low tendencies toward PIPU group. This result suggests that individuals with high tendencies toward PIPU allocate more attentional resources for novelty processing. Enhanced brain responding to novel sexual stimuli may facilitate pornographic consumption and play an essential role in the development and maintenance of PIPU.

A Review of Associations between Externalizing Behaviors and Prenatal Cannabis Exposure: Limitations & Future Directions

In utero cannabis exposure can disrupt fetal development and increase risk for various behavioral disruptions, including hyperactivity, inattention, delinquent behaviors, and later substance abuse, among others. This review summarizes the findings from contemporary investigations linking prenatal cannabis exposure to the development of psychopathology and identifies the limitations within the literature, which constrain our interpretations and generalizability. These limitations include a lack of genetic/familial control for confounding and limited data examining real world products, the full range of cannabinoids, and motives for use specifically in pregnant women. Taken together, our review reveals the need to continue to improve upon study designs in order to allow researchers to accurately draw conclusions about the development of behavioral consequences of prenatal cannabis exposure. Findings from such studies would inform policy and practices regarding cannabis use during pregnancy and move the field toward developing a comprehensive teratogenic profile of cannabis similar to what is characterized in the prenatal alcohol and tobacco literature.

Genetic architecture of four smoking behaviors using partitioned SNP heritability

BACKGROUND AND AIMS

Although genome-wide association studies have identified many loci that influence smoking behaviors, much of the genetic variance remains unexplained. We characterized the genetic architecture of four smoking behaviors using single nucleotide polymorphism (SNP) heritability (h²_SNP ). This is an estimate of narrow-sense heritability specifically estimating the proportion of phenotypic variation due to causal variants (CVs) tagged by SNPs.

DESIGN

Partitioned h²_SNP analysis of smoking behavior traits.

SETTING

UK Biobank.

PARTICIPANTS

UK Biobank participants of European ancestry. The number of participants varied depending on the trait, from 54 792 to 323 068.

MEASUREMENTS

Smoking initiation, age of initiation, cigarettes per day (CPD; count, log-transformed, binned and dichotomized into heavy versus light) and smoking cessation with imputed genome-wide SNPs.

FINDINGS

We estimated that, in aggregate, approximately 18% of the phenotypic variance in smoking initiation was captured by imputed SNPs [h²_SNP = 0.18, standard error (SE) = 0.01] and 12% [SE = 0.02] for smoking cessation, both of which were more than twice the previously reported estimates. Estimated age of initiation (h²_SNP  = 0.05, SE = 0.01) and binned CPD (h²_SNP  = 0.1, SE = 0.01) were substantially below published twin-based h² of 50%. CPD encoding influenced estimates, with dichotomized CPD h²_SNP  = 0.28. There was no evidence of dominance genetic variance for any trait.

CONCLUSION

A biobank study of smoking behavior traits suggested that the phenotypic variance explained by SNPs of smoking initiation, age of initiation, cigarettes per day and smoking cessation is modest overall.

Novelty preferences and cocaine-associated cues influence regions associated with the salience network in juvenile female rats

Preferences for novel environments (novelty-seeking) is a risk factor for addiction, with little known about its underlying circuitry. Exposure to drug cues facilitates addiction maintenance, leading us to hypothesize that exposure to a novel environment activates a shared neural circuitry. Stimulation of the D1 receptor in the prelimbic cortex increases responsivity to drug-associated environments. Here, we use D1 receptor overexpression in the prelimbic cortex to probe brain responses to novelty-preferences (in a free-choice paradigm) and cocaine-associated odors following place conditioning. These same cocaine-conditioned odors were used to study neural circuitry with Blood Oxygen Level Dependent (BOLD) activity. D1 overexpressing females had deactivated BOLD signals related to novelty-preferences within the insula cortex and amygdala and activation in the frontal cortex and dopamine cell bodies. BOLD responses to cocaine cues were also sensitive to D1. Control females demonstrated a place preference for cocaine environments with no significant BOLD response, while D1 overexpressing females demonstrated a place aversion and weak BOLD responses to cocaine-conditioned odor cues within the insula cortex. For comparison, we provide data from an earlier study with juvenile males overexpressing D1 that show a strong preference for cocaine and elevated BOLD responses. The results support the use of a pharmacological manipulation (e.g., D1 overexpression) to probe the neural circuitry downstream from the prelimbic cortex.

Sensation seeking versus alcohol use: Evaluating temporal precedence using cross-lagged panel models

BACKGROUND

Sensation seeking has been theoretically conceptualized as the personality trait for novel and complex experiences responsible for the predilection of engaging in risky activities. The study evaluated several cross-lagged panel models premised on various measurement variations of sensation seeking to determine the extent that each representation operates as the temporal antecedent or consequent of alcohol use.

METHODS

Participants (N = 201) were United States college students under 21 years of age. The measures, completed in two assessments separated by a month, included the Sensation Seeking Scale-V (SSS-V) and its subscales of boredom susceptibility, disinhibition, experience seeking, thrill & adventure seeking; the Brief Sensation Seeking Scale (BSSS); and the frequency and quantity of alcoholic drinks. Cross-lagged panel models containing synchronous correlations, auto-regressive paths, and cross-lagged paths were estimated in path analysis using structural equation modeling.

RESULTS

The cross-lagged panel model results varied depending on the measurement variant of sensation seeking. The SSS-V emerged as a longitudinal precursor to both drink frequency and quantity. Thrill & adventure seeking longitudinally anticipated drink frequency and quantity. However, disinhibition and drink quantity reciprocally reinforced one another across time. Boredom susceptibility and experience seeking did not exhibit any temporal directionality with alcohol behaviors. Furthermore, the BSSS operated as a longitudinal precursor of drink quantity.

CONCLUSIONS

Findings help to unravel the temporal precedent of sensation seeking versus alcohol behaviors based on the scrutiny of various sensation seeking measurement approaches.

Conduct disorder and somatic health in children: a nationwide genetically sensitive study

BACKGROUND

Conduct disorder (CD), a serious behavioral and emotional disorder in childhood and adolescence, characterized by disruptive behavior and breaking societal rules. Studies have explored the overlap of CD with neurodevelopmental problems (NDP). The somatic health of children with NDP has been investigated; however, the prevalence of these problems in children with CD has not been sufficiently studied. Holistic assessment of children with CD is required for establishing effective treatment strategies.

AIMS

(1) Define the prevalence of selected neurological problems (migraine and epilepsy) and gastrointestinal problems (celiac disease, lactose intolerance, diarrhea, and constipation) in a population of twins aged 9 or 12; (2) Compare the prevalence of somatic problems in three subpopulations: (a) children without CD or NDP, (b) children with CD, and (c) children with both CD and NDP; (3) Select twin pairs where at least one child screened positive for CD but not NDP (proband) and map both children's neurological and gastrointestinal problems.

METHOD

Telephone interviews with parents of 20,302 twins in a cross-sectional, nationwide, ongoing study. According to their scores on the Autism-Tics, AD/HD, and Comorbidities inventory, screen-positive children were selected and divided into two groups: (1) children with CD Only, (2) children with CD and at least one NDP.

RESULTS

Children with CD had an increased prevalence of each neurological and gastrointestinal problem (except celiac disease), and the prevalence of somatic problems was further increased among children with comorbid CD and NDP. The presence of CD (without NDP) increased the odds of constipation for girls and the odds of epilepsy for boys. Girls with CD generally had more coexisting gastrointestinal problems than boys with CD. Female co-twins of probands with CD were strongly affected by gastrointestinal problems. Concordance analyses suggested genetic background factors in neurological and gastrointestinal problems, but no common etiology with CD could be concluded.

CONCLUSION

Co-occurring NDP could explain most of the increased prevalence of somatic problems in CD. Our results raise a new perspective on CD in children and adolescents; their CD seems to be linked to a number of other health problems, ranging from neurodevelopmental and psychiatric disorders to somatic complaints.

The Role of A Priori-Identified Addiction and Smoking Gene Sets in Smoking Behaviors

INTRODUCTION

Smoking is a leading cause of death, and genetic variation contributes to smoking behaviors. Identifying genes and sets of genes that contribute to risk for addiction is necessary to prioritize targets for functional characterization and for personalized medicine.

METHODS

We performed a gene set-based association and heritable enrichment study of two addiction-related gene sets, those on the Smokescreen Genotyping Array and the nicotinic acetylcholine receptors, using the largest available GWAS summary statistics. We assessed smoking initiation, cigarettes per day, smoking cessation, and age of smoking initiation.

RESULTS

Individual genes within each gene set were significantly associated with smoking behaviors. Both sets of genes were significantly associated with cigarettes per day, smoking initiation, and smoking cessation. Age of initiation was only associated with the Smokescreen gene set. Although both sets of genes were enriched for trait heritability, each accounts for only a small proportion of the single nucleotide polymorphism-based heritability (2%-12%).

CONCLUSIONS

These two gene sets are associated with smoking behaviors, but collectively account for a limited amount of the genetic and phenotypic variation of these complex traits, consistent with high polygenicity.

IMPLICATIONS

We evaluated evidence for the association and heritable contribution of expert-curated and bioinformatically identified sets of genes related to smoking. Although they impact smoking behaviors, these specifically targeted genes do not account for much of the heritability in smoking and will be of limited use for predictive purposes. Advanced genome-wide approaches and integration of other 'omics data will be needed to fully account for the genetic variation in smoking phenotypes.

Identifying Early Risk Factors for Addiction Later in Life: A Review of Prospective Longitudinal Studies

PURPOSE OF REVIEW

To review prospective longitudinal studies that have identified risk factors for the development of substance use disorders in adulthood from individual differences during childhood and adolescence.

RECENT FINDINGS

Risk factors during childhood and adolescence that have been consistently linked to increased risk for addiction include externalizing and internalizing symptoms, early substance use, and environmental influences, such as parental behavior and exposure to traumatic experiences.

SUMMARY

Since the etiology of substance use disorders is complex and likely is attributable to many causal pathways, systematic examination of the associations between risk factors will be necessary to understand the mixed findings in the existing literature, to determine which individuals should be targeted for prevention efforts, and to design interventions that address risk factors that are most likely to improve outcomes.

The association between early life mental health and alcohol use behaviours in adulthood: A systematic review

This systematic review aims to summarise current evidence on the association between early life mental health and alcohol use behaviours in adulthood. Peer-reviewed publications were located by searching EMBASE, Medline, PsycINFO, and the ISI Web of Science up to 31 October 2018. Prospective longitudinal studies reporting associations between externalising problems (EXT), internalising problems (INT), depression, anxiety before age 18, and alcohol use behaviours (alcohol consumption, heavy/problematic drinking, alcohol use disorder) after age 18 were included. After screening 17259 articles, 36 articles met the inclusion criteria. Information extracted included strength of associations, age when mental health and alcohol use behaviours were measured, sex differences in the association, and other sample characteristics. 103 tests in 23 articles were identified on the externalising domain and 135 tests in 26 articles on the internalising domain. 37 out of 103 tests reported positive associations between EXT and alcohol use behaviours. The likelihood of observing positive associations was higher for more severe alcohol use outcomes, but this trend disappeared among high-quality studies. Findings on associations between internalising domain and alcohol use varied across their subtypes. INT tended to be negatively associated with alcohol consumption but positively associated with more severe outcomes (heavy/problematic drinking, alcohol use disorder). Depression tended to be positively associated with alcohol outcomes, while no clear association between anxiety and alcohol outcomes was evident. Variation of the association across developmental timing, sex, culture, historical period was explored where appropriate. Great heterogeneity in the current literature calls for greater attention to view the relationship developmentally.

Adolescent Externalizing Psychopathology and Its Prospective Relationship to Marijuana Use Development from Age 14 to 30: Replication Across Independent Longitudinal Twin Samples

Externalizing psychopathology in early adolescence is a highly heritable risk factor for drug use, yet how it relates to marijuana use development is not well-characterized. We evaluate this issue in independent twin samples from Colorado (N = 2608) and Minnesota (N = 3630), assessed from adolescence to early adulthood. We used a biometric latent growth model of marijuana use frequency with data from up to five waves of assessment from ages 14 to 30, to examine change in marijuana use and its relationship with a factor model of adolescent externalizing psychopathology. The factor structure of adolescent externalizing psychopathology was similar across samples, as was the association between that common factor and early marijuana use (Minnesota r = 0.67 [0.60, 0.75]; Colorado r = 0.69 [0.59, 0.78]), and increase in use (Minnesota r = 0.18 [0.10, 0.26]; Colorado r = 0.20 [0.07, 0.34]). Early use was moderately heritable in both samples (Minnesota h² = 0.57 [0.37, 0.79]; Colorado h² = 0.42 [0.14, 0.73]). Increase in use was highly heritable in Minnesota (h² = 0.82 [0.72, 0.88]), less so in Colorado (h² = 0.22 [0.01, 0.66]), and shared environmental effects were larger in Colorado (c² = 0.55 [0.14, 0.83]) than Minnesota (c² = 0 [0, 0.06]). We found moderate genetic correlations between externalizing psychopathology and early use in both samples. Finally, additional analyses in the Minnesota sample indicated that marijuana use decreased during the late 20s. This decline is strongly heritable (h² = 0.73 [0.49, 0.91]) and moderately negatively correlated with adolescent externalizing psychopathology (r = - 0.41 [- 0.54, - 0.28]). Adolescent externalizing psychopathology is genetically correlated with change in late adolescent marijuana use (late teens, early 20s), as well as maintenance of use in early adulthood (late 20 s) even after controlling for the effects of early use.

Externalizing and internalizing symptoms in childhood and adolescence and the risk of alcohol use disorders in young adulthood: A meta-analysis of longitudinal studies

BACKGROUND

Evidence suggests that externalizing and internalizing symptoms are expressed early in life and are associated with problematic drinking in young adulthood. However, few studies have examined their role during childhood and adolescence in predicting alcohol problems later in life.

OBJECTIVES

To examine the role of childhood and adolescent externalizing and internalizing symptoms in predicting alcohol use disorders in young adulthood.

METHODS

We searched five electronic databases (PubMed, Scopus, PsycINFO, Web of Sciences and Embase) for studies which diagnosed alcohol use disorders through either the International Classification of Diseases or American Psychiatric Association - Diagnostic and Statistical Manual of Mental Disorders criteria and followed up children or adolescents into the transition to young adulthood. We performed a meta-analysis and obtained pooled odds ratio estimates with 95% confidence intervals using random-effects models.

RESULTS

A total of 12 longitudinal studies met eligibility criteria and were included in the meta-analysis. All measured the outcome using Diagnostic and Statistical Manual of Mental Disorders criteria. The majority were of good quality and were conducted in the United States. A total of 19,407 participants (50% female) were included in this meta-analysis. Of these, n = 2337 (12%) had diagnoses of alcohol use disorders/alcohol dependence. Participant ages ranged from birth to 36 years. Internalizing symptoms increased the risk of young adult alcohol use disorders by 21% (odds ratio = 1.21; 95% confidence interval = [1.05, 1.39]), with no strong evidence of publication bias. Subgroup analysis suggested significantly lower heterogeneity than for externalizing studies. Externalizing symptoms increased the risk of alcohol use disorders by 62% (odds ratio = 1.62, 95% confidence interval = [1.39, 1.90]). We found some evidence of publication bias and significant heterogeneity in the studies.

CONCLUSION

Our findings highlight the contribution of early behavioural problems to the development of alcohol use disorders in young adulthood and the need for timely scrutiny of and intervention on early behavioural problems.

Non-overlapping and Inverse Associations Between the Sexes in Structural Brain-Trait Associations

Personality reflects the set of psychological traits and mechanisms characteristic for an individual. The brain-trait association between personality and gray matter volume (GMv) has been well studied. However, a recent study has shown that brain structure-personality relationships are highly dependent on sex. In addition, the present study investigates the role of sex on the association between temperaments and regional GMv. Sixty-six participants (33 male) completed the Temperament and Character Inventory (TCI) and underwent structural magnetic resonance brain imaging. Mann-Whitney U tests showed a significant higher score on Novelty Seeking (NS) and Reward Dependence (RD) for females, but no significant group effects were found for Harm Avoidance (HA) and Persistence (P) score. Full factor model analyses were performed to investigate sex-temperament interaction effects on GMv. This revealed increased GMv for females in the superior temporal gyrus when linked to NS, middle temporal gyrus for HA, and the insula for RD. Males displayed increased GMv compared to females relating to P in the posterior cingulate gyrus, the medial superior frontal gyrus, and the middle cingulate gyrus, compared to females. Multiple regression analysis showed clear differences between the brain regions that correlate with female subjects and the brain correlates that correlate with male subjects. No overlap was observed between sex-specific brain-trait associations. These results increase the knowledge of the role of sex on the structural neurobiology of personality and indicate that sex differences reflect structural differences observed in the normal brain. Furthermore, sex hormones seem an important underlying factor for the found sex differences in brain-trait associations. The present study indicates an important role for sex in these brain structure-personality relationships, and implies that sex should not just be added as a covariate of no interest.

Disinhibition as a unifying construct in understanding how personality dispositions undergird psychopathology

Disinhibition has been a construct of interest for decades, as evidenced by its inclusion in most prominent models of general personality functioning and its link to personality pathology, other psychopathology, health behaviors, and public health concerns. Disinhibition is manifest in behavioral, task based, and physiological measures, and common etiologies are a major reason for the coherence of the domain across a variety of assessment modalities. The current review will provide a summary of the conceptualization of the construct across prominent models, its link to psychopathology and maladaptive behaviors, and its etiology. Finally, we provide discussion on its clinical application utilizing disinhibition to aid in understanding comorbid psychopathology and through a description of its potential use in treatment.

ADOLESCENTS´ PERCEPTION OF HARMS, BENEFITS AND INTENTION TO USE MARIJUANA WITHIN THE CONTEXT OF REGULATORY CHANGES IN BELIZE

ABSTRACT Objective: to evaluate the perception of harm and benefits from using marijuana in adolescents’, to determine lifetime, past year and past month prevalence of marijuana use; and to analyze the relationship between marijuana use and the perception of harm and benefits from using marijuana. Methods: multi-centric, quantitative cross sectional survey design method was utilized for this research. Data was collected using structured standardized approved questionnaire. A total of 273 students from three high schools in two cities of the country of Belize participated in the survey conducted in 2015. Results: lifetime prevalence of marijuana use of 41.4% (39.2% past year, 24.9% past 30 days), and average age of onset of 12 years. First time prevalence of marijuana use among students by sex indicated 53.1% male students used marijuana as compared to 46.9% female students with no significant (p>0.05) statistical difference seen between genders. Participants reported that their friends use marijuana (45.1%); while 68.1% of the marijuana users had some friends that use marijuana. 51% of the students surveyed stated that they would not use marijuana, even if it were legally available. The majority (70%) perceived no risk to using marijuana occasionally. Statistical analysis revealed that a high perception of benefits, a low risk perception and friends’ use of marijuana was associated with individual use as well as intention to use in a hypothetical context of regulatory changes. Conclusion: the Belizean school-aged adolescents are more than likely to smoke marijuana because of friends’ influence, low perception of risks and if marijuana is legally available and accessible to them.

Genetic correlation of antisocial behaviour with alcohol, nicotine, and cannabis use

BACKGROUND

There is high comorbidity between antisocial behaviour (ASB) and substance use, and twin studies have shown that part of the covariation is due to overlapping genetic influences. Here we used measured genetic effects to estimate the genetic correlations of ASB with nicotine, alcohol, and cannabis use.

METHODS

We meta-analysed data from two genome-wide association studies for ASB and used existing summary statistics from the largest genome-wide association studies into substance use (ever smoking, cigarettes smoked per day, weekly alcohol consumption, and lifetime cannabis use). We performed cross-trait LD-score regression to estimate genetic correlations between ASB and substance use phenotypes explained by all single nucleotide polymorphisms (SNPs). When significant, we tested whether the signs of the regression coefficients of SNPs from the ASB and substance use phenotypes were in the same direction across multiple p-value thresholds and examined enrichment in overlap of the strongest associated SNPs.

RESULTS

We found nominally significant genetic correlations of ASB with lifetime cannabis use (r_g = 0.69, p=.016) and cigarettes per day (r_g = 0.59, p = 0.036) but not with weekly alcohol consumption or ever smoking. Sign-tests revealed consistent directions of effect of SNPs for ASB and cannabis use for all p-value thresholds except the most stringent one, whereas for ASB with cigarettes per day no consistent evidence was found. We found no evidence of enrichment in overlap of the most associated SNPs across these traits.

CONCLUSION

Using measured genetic variants, we found preliminary support for a genetic correlation of ASB with lifetime cannabis use and cigarettes per day.

Gray Matter Volume of a Region in the Thalamic Pulvinar Is Specifically Associated with Novelty Seeking

Personality reflects the set of psychological traits and mechanisms characteristic for an individual. Geno-neuro-biologically inspired personality accounts have proposed a set of temperaments and characters that jointly compose personality profiles. The present study addresses the link between neurobiology and personality and investigates the association between temperament traits and regional gray matter volume. Furthermore, the specificity of these associations as well as the underlying components that drive the association are addressed. One hundred and four participants completed the Temperament and Character Inventory (TCI) and underwent structural magnetic resonance brain imaging. The participants included premanifest carriers of Huntington's disease, as this population is associated with temperament-related neuropsychiatric symptoms. Whole brain voxel-based multiple regression analyses on gray matter volume revealed a significant specific positive correlation between a region in the left thalamic pulvinar and novelty seeking score, controlled for the other traits (P_height < 0.05, FWE-corrected). No significant associations were observed for the other temperament traits. Region of interest analyses showed that this association is driven by the subscale NS2: impulsiveness. The results increase the knowledge of the structural neurobiology of personality and indicate that individual differences in novelty seeking reflect the structural differences observed in the brain in an area that is widely and densely connected, which is in line with the typically domain-general behavioral influence of personality traits on a wide range of affective, perceptual, mnemotic, executive, and other cognitive functions.

Distinct pathological profiles of inmates showcasing cluster B personality traits, mental disorders and substance use regarding violent behaviors

High rates of violence are found amid offenders with severe mental illnesses (SMI), substance use disorders (SUDs) and Cluster B personality disorders. Elevated rates of comorbidity lead to inconsistencies when it comes to this relationship. Furthermore, overlapping Cluster B personality traits have been associated with violence. Using multiple correspondence analysis and cluster analysis, this study was designed to differentiate profiles of 728 male inmates from penitentiary and psychiatric settings marked by personality traits, SMI and SUDs following different violent patterns. Six significantly differing clusters emerged. Cluster 1, "Sensation seekers", presented recklessness with SUDs and low prevalence's of SMI and auto-aggression. Two clusters committed more sexual offenses. While Cluster 2, "Opportunistic-sexual offenders", had more antisocial lifestyles and SUDs, Cluster 6, "Emotional-sexual offenders", displayed more emotional disturbances with SMI and violence. Clusters 3 and 4, representing "Life-course-persistent offenders", shared early signs of persistent antisocial conduct and severe violence. Cluster 3, "Early-onset violent delinquents", emerged as more severely antisocial with SUDs. Cluster 4, "Early-onset unstable-mentally ill delinquents", were more emotionally driven, with SMI and auto-aggression. Cluster 5, "Late-start offenders", was less severely violent, and emotionally driven with antisocial behavior beginning later. This study suggests the presence of specific psychopathological organizations in violent inmates.

Past 15-year trends in lifetime cocaine use among US high school students

BACKGROUND

Most recent research on adolescent drug use has focused on alcohol, tobacco, and marijuana. Less is known about the recent epidemiology of adolescent cocaine use, which has serious health consequences.

PURPOSE

To describe recent trends in cocaine use by U.S. high school students, and identify differences in lifetime and repeated use across sex and racial/ethnic groups.

METHODS

We used data from the national Youth Risk Behavior Surveys (YRBS) from 1999 to 2015. We estimated the prevalence of lifetime cocaine use (LCU) and repeated lifetime cocaine use (RLCU) across years by race/ethnicity and sex and tested for linear and quadratic trends.

RESULTS

The prevalence of LCU decreased from 1999 to 2015 (9.54%-5.19%). RLCU also decreased (5.13%-2.84%). Despite the overall decline, LCU and RLCU both rose between 2009-2015 (LCU:2.78%-5.19%, RLCU:1.58%-2.84%). Boys had higher rates of LCU and RLCU than girls (LCU:6.42% vs 4.65%; RLCU:3.69% vs 2.18%). American Indian/Alaskan Native, Native Hawaiian/Pacific Islander, and Hispanic adolescents had the highest overall prevalence of LCU. Black adolescents' LCU patterns differed from other racial/ethnic groups. The prevalence of LCU among Black boys increased over time, while the prevalence for Black girls remained consistently low.

CONCLUSIONS

Adolescent cocaine use is less common today than in the 1990s. However, rates of adolescent cocaine use have risen across all racial/ethnic groups in the past few years. Public health efforts should address at risk groups with particularly high or rising rates of cocaine use.

Cloninger's Temperament and Character Dimensions of Personality and Binge Drinking Among College Students

BACKGROUND

Temperament and character dimensions of personality remain largely unexplored in young adults exhibiting binge drinking (BD) patterns. Moreover, the available studies do not consider gender differences and dismiss possible personality heterogeneity among binge drinkers. In this study, we aimed to compare temperament and character dimensions between young binge drinkers and age- and sex-matched social drinkers. We further applied cluster analysis to investigate the potential heterogeneity of personality patterns among BD college students.

METHODS

This study included 200 university students of 18 to 24 years of age, who were recruited via an invitation to take an alcohol use survey. These participants included 100 individuals (50 females and 50 males) with a BD pattern, and 100 participants (50 females and 50 males) with a social drinking (SD) pattern. These subjects were evaluated with regard to their use of alcohol and other substances, impulsiveness, sensation seeking, mood, and Cloninger's Temperament and Character Inventory.

RESULTS

Between-group comparisons revealed that both male and female binge drinkers were characterized by high levels of novelty seeking, and low levels of persistence and self-directedness. However, cluster analyses within the binge drinker group revealed 2 distinct groups that differed between males and females. These groups shared similarities with Cloninger's type I (high harm-avoidance) and II (high novelty-seeking) alcoholism typology.

CONCLUSIONS

The present findings support the subdivision of binge drinkers according to gender and personality dimensions. Male and female binge drinkers should not be considered a unitary group, but rather a population of individuals that encompasses at least 2 distinct personality patterns. These findings have major implications for prevention and treatment approaches.

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

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

Gender Differences in Relations among Perceived Family Characteristics and Risky Health Behaviors in Urban Adolescents

BACKGROUND

Research regarding the role of gender in relations between family characteristics and health risk behaviors has been limited.

PURPOSE

This study aims to investigate gender differences in associations between family processes and risk-taking in adolescents.

METHODS

Adolescents (N = 249; mean age = 14.5 years) starting their first year at an urban high school in the northeastern USA completed self-report measures that assessed family characteristics (i.e., parental monitoring, family social support, family conflict) and health behaviors (i.e., tobacco use, alcohol use, marijuana use, sex initiation) as part of a prospective, community-based study. Multivariate logistic regression models were used to investigate gender differences in associations between the family characteristics and health behaviors.

RESULTS

Among males, higher levels of perceived parental monitoring were associated with lower odds of using tobacco and having ever engaged in sex. Among females, higher levels of perceived parental monitoring were associated with lower odds of marijuana use, alcohol use, and having ever engaged in sex. However, in contrast to males, among females (a) higher levels of perceived family social support were associated with lower odds of alcohol use and having ever engaged in sex and (b) higher levels of perceived family conflict were associated with higher odds of marijuana use and having ever engaged in sex.

CONCLUSION

Family processes were more strongly related to health behaviors among adolescent females than adolescent males. Interventions that increase parental monitoring and family social support as well as decrease family conflict may help to protect against adolescent risk taking, especially for females.

Main mental disorders in crack-cocaine users treated at Psychosocial Care Centers for Alcohol and Drugs in the city of Recife, Brazil

Abstract Introduction: Brazil's Northeast region has the highest crack-cocaine consumption in the country. Crack-cocaine has more intense effects than cocaine powder and can cause greater chemical dependence. Psychosocial Care Centers for Alcohol and Drugs (CAPSad) are public health services that provide treatment for drug dependence. It is common for drug users, and particularly crack-cocaine users, to develop mental disorders. Objective: To evaluate the most common mental disorders in crack-cocaine dependents in treatment at CAPSad in the city of Recife, Brazil. Methods: The research database "Between rocks and shots: user profiles, consumption strategies, and social impact of crack cocaine" (CEP/CCS/UFPE no. 206/11) was consulted to establish the areas of crack cocaine consumption in the city of Recife. Results: There were 885 patients in treatment for crack-cocaine use, with a mean age of 29.8±9.4 years. The mean duration of drug use was 6.1±4.6 years. Most of the patients were males (80.3%), had left school at some point between the 1st and 9th grades (45.6%), were unemployed and/or seeking employment (52%) and used drugs daily (56.4%). Cocaine chemical dependence was more significant when correlated with use of crack-cocaine and other drugs such as medications and hallucinogens (p = 0.01). Conclusions: Data from this study showed strong associations between crack-cocaine uses and development of mental disorders, particularly when abuse of multiple substances occurs. Based on these data, there is a clear need for coordination of related public policies for support and social reintegration to provide these people with comprehensive care.

Childhood attention-deficit/hyperactivity disorder symptoms and the development of adolescent alcohol problems: A prospective, population-based study of Swedish twins

Children with attention-deficit/hyperactivity disorder (ADHD) are at increased risk of problematic alcohol and other substance use in adolescence. This study used data from an ongoing, prospective, population-based twin study of Swedish children and adolescents to evaluate the extent to which the association between ADHD symptoms and alcohol problems reflects a unique source of genetic or environmental risk related to ADHD versus a broader predisposition to youth externalizing behavior. We used all available data from same-sex monozygotic (MZ) and dizygotic (DZ) twins on ADHD symptoms in childhood (age 9/12; N = 15,549) and alcohol problems in late adolescence (age 18; N = 2,564). Consistent with prior longitudinal studies, the phenotypic association between hyperactive/impulsive ADHD symptoms and alcohol problems was small in magnitude, whereas the association for inattentive symptoms was even weaker. Additive genetic influences explained 99.8% of the association between hyperactive/impulsive symptoms and alcohol problems. Furthermore, we found that the genetic risk specifically associated with hyperactive/impulsive symptoms was attenuated when estimated in the context of externalizing behavior liability during childhood, of which ADHD symptoms were specific expressions. In sensitivity analyses exploring hyperactivity in mid-adolescence, we found a similar pattern of genetic associations. These results are consistent with previous findings of genetically driven overlap in the etiology of ADHD and problematic alcohol use. At least some of this co-occurrence may result from a general predisposition to externalizing behaviors in youth. © 2015 Wiley Periodicals, Inc.

The indirect effects of childhood attention deficit hyperactivity disorder on alcohol problems in adulthood through unique facets of impulsivity

BACKGROUND AND AIMS

Research has not studied unique impulsivity dimensions as prospective links between childhood attention deficit hyperactivity disorder (ADHD) and alcohol problems. We examined the association between childhood ADHD, five facets of impulsivity and alcohol problems in adulthood and the indirect effects of childhood ADHD-to-impulsivity-to-alcohol problems.

DESIGN, SETTING AND PARTICIPANTS

Participants were from a longitudinal study (n = 289, meanage  = 28.67) of individuals with (n = 170) and without (n = 119) childhood ADHD. The ADHD sample, as part of an ADHD summer treatment program, was diagnosed initially in childhood (1987-96, Pittsburgh, PA, USA) via structured parent interview and standardized parent/teacher ratings. The ADHD sample and demographically similar individuals without ADHD (living in the greater Pittsburgh area) were recruited to participate in the Pittsburgh ADHD Longitudinal Study (PALS) between 1999 and 2003.

MEASUREMENTS

Self-reported impulsivity (UPPS-P) and alcohol-related problems were assessed in adulthood (2011-14).

FINDINGS

Adults with, compared with those without, childhood ADHD had more alcohol problems (β = 0.34, P < 0.05) and higher levels of negative urgency, positive urgency, lack of perseverance and lack of planning (βs = 0.24-0.31, Ps < 0.001). Impulsivity facets (except sensation-seeking) were related to number of alcohol problems (βs = 0.34-0.61, Ps < 0.05). Negative (β = 0.26, P < 0.01) and positive (β = 0.27, P < 0.01) urgency mediated the association between childhood ADHD and number of adult alcohol problems.

CONCLUSIONS

Elevated levels of emotional impulsivity (negative/positive urgency) may place children with attention deficit hyperactivity disorder at increased risk for alcohol problems in adulthood.

Role of parenting styles in adolescent substance use: results from a Swedish longitudinal cohort study

OBJECTIVE

Adolescent substance use is an area of concern because early substance use is associated with a higher risk of adverse outcomes. Parenting style, defined as the general style of parenting, as well as substance-specific parenting practices may influence children's substance use behaviour. The present study aims to probe the impact of parenting style on adolescent substance use.

METHOD

A cohort of 1268 adolescents (48% girls), aged 12-13 years at baseline, from 21 junior high schools was assessed in the first semester of junior high school, and then again in the last semester of the 9th grade, 32 months later. Parenting style, operationalised as a fourfold classification of parenting styles, including established risk factors for adolescent substance use, were measured at baseline.

RESULTS

Neglectful parenting style was associated with worse substance use outcomes across all substances. After adjusting for other proximal risk factors in multivariate analyses, parenting style was found to be unrelated to substance use outcomes with one exception: authoritative parenting style was associated with less frequent drinking. Association with deviant peers, delinquent behaviour, provision of alcohol by parents, and previous use of other substances were associated with substance use outcomes at follow-up.

CONCLUSIONS

The results of the present study indicate that parenting style may be less important for adolescent substance use outcomes than what has previously been assumed, and that association with deviant peers and delinquent behaviour may be more important for adolescent substance use outcomes than general parenting style.

Shared additive genetic influences on DSM-IV criteria for alcohol dependence in subjects of European ancestry

BACKGROUND AND AIMS

Genetic studies of alcohol dependence (AD) have identified several candidate loci and genes, but most observed effects are small and difficult to reproduce. A plausible explanation for inconsistent findings may be a violation of the assumption that genetic factors contributing to each of the seven DSM-IV criteria point to a single underlying dimension of risk. Given that recent twin studies suggest that the genetic architecture of AD is complex and probably involves multiple discrete genetic factors, the current study employed common single nucleotide polymorphisms in two multivariate genetic models to examine the assumption that the genetic risk underlying DSM-IV AD is unitary.

DESIGN, SETTING, PARTICIPANTS, MEASUREMENTS

AD symptoms and genome-wide single nucleotide polymorphism (SNP) data from 2596 individuals of European descent from the Study of Addiction: Genetics and Environment were analyzed using genomic-relatedness-matrix restricted maximum likelihood. DSM-IV AD symptom covariance was described using two multivariate genetic factor models.

FINDINGS

Common SNPs explained 30% (standard error=0.136, P=0.012) of the variance in AD diagnosis. Additive genetic effects varied across AD symptoms. The common pathway model approach suggested that symptoms could be described by a single latent variable that had a SNP heritability of 31% (0.130, P=0.008). Similarly, the exploratory genetic factor model approach suggested that the genetic variance/covariance across symptoms could be represented by a single genetic factor that accounted for at least 60% of the genetic variance in any one symptom.

CONCLUSION

Additive genetic effects on DSM-IV alcohol dependence criteria overlap. The assumption of common genetic effects across alcohol dependence symptoms appears to be a valid assumption.

Antisocial behavior reduces the association between subdimensions of ADHD symptoms and alcohol use in a large population-based sample of adolescents

The aim of this study was to investigate possible effects of antisocial behavior on reducing the association between subdimensions of ADHD symptoms (inattention, hyperactivity and impulsivity) and alcohol use. Boys and girls were analyzed separately using a population-based Swedish adolescent sample. A randomly selected cross-sectional survey was performed in secondary and upper secondary schools in Västmanland County during 2010. Participants were a population of 2,439 15-16 year-olds and 1,425 17-18 year-olds (1,947 girls and 1,917 boys). Psychosocial adversity, antisocial behaviors, symptoms of ADHD and alcohol use were assessed by questionnaires. Except for girls' inattention, subdimensions of ADHD symptoms were not associated with alcohol use when variance due to antisocial behavior was accounted for. Among boys, instead of an indirect effect of antisocial behavior on the association between impulsivity and alcohol use, a moderating effect was found. Among girls, the inattention component of ADHD was independently associated with alcohol use even when adjusted for antisocial behavior. The reduced associations between symptoms of hyperactivity, impulsivity, and alcohol use for boys and girls after adjusting for antisocial behavior suggest a considerable overlap between hyperactivity, impulsivity, and antisocial behavior. The direct pathway between inattention and alcohol use among girls suggests that girls with inattention symptoms are at risk of alcohol use regardless of antisocial behavior. Special attention should be given to these girls. Accounting for antisocial behavior reduced the relation between subdimensions of ADHD symptoms and alcohol use, and antisocial behaviors should therefore be screened for when symptoms of ADHD are present.

Novelty Seeking as a Phenotypic Marker of Adolescent Substance Use

Trait novelty seeking has been consistently implicated in substance use, yet the origins and mechanisms of novelty seeking in substance use proneness are unclear. We aimed to characterize novelty seeking as a phenotypic marker of substance use proneness in adolescence, a critical period for drug use experimentation. To this end, we parsed novelty seeking's two constituent subdimensions - exploratory excitability (drive for novel experience) and impulsiveness (careless decision-making) - and explored the individual relations of these dimensions to: (1) the use of a variety of licit and illicit substances, (2) family history of substance use, and (3) subjective drug effects. Five hundred eighty five adolescents (mean age = 14.5 years) completed surveys of key variables. Results indicated that, when accounting for the covariation among exploratory excitability and impulsiveness, impulsiveness emerged as the more salient correlate of substance use and was independently associated with initiation of nearly all drug classes. Mediation analyses of the mechanisms of novelty seeking-related risk illustrated that impulsiveness mediated the association of family history of substance use with both initiation and past 30-day frequency of use. Both impulsiveness and exploratory excitability were associated with increased positive and negative subjective drug effects, and the analyses supported a significant indirect pathway from impulsiveness to a more frequent use via positive subjective effects. Although limited by a cross-sectional design, these findings suggest that impulsiveness-like aspects of the novelty seeking construct may represent a useful phenotypic marker for early substance use proneness that potentially (1) increases initiation risk, (2) has familial origins, and (3) promotes more frequent use by altering subjective drug response.

Gender, psychopathy factors, and intimate partner violence

The present study sheds light on relationships between distinct psychopathic traits and perpetration of intimate partner violence (IPV) in women versus men. Men and women with recent drug and/or violence histories (N = 250) were assessed for psychopathic traits using the Psychopathy Checklist: Screening Version and for their and their partner's use of IPV with the Revised Conflict Tactics Scale. The first goal was to examine the moderating role of gender in psychopathy factor relationships to IPV. Although both the interpersonal-affective traits (Factor1) and the impulsive-antisocial traits (Factor 2) of psychopathy were related to higher frequency of IPV perpetration, the relationship between Factor 1 and IPV was stronger in men. Our second goal examined the moderating role of psychopathy traits in the relationship between partner's perpetration of IPV and participant perpetration (mutual violence) in the 2 genders. Relationships between partner- and self-IPV were similar at both low and high levels of Factor 1 in men, although the partner- and self-IPV relationship was significantly stronger among women at low relative to high levels of Factor 1. The relationship between partner- and self-IPV was stronger at high levels of Factor 2 in men, whereas Factor 2 did not moderate mutual violence in women. These results indicate that relationships between psychopathy factors and IPV differ by gender, with psychopathy generally exacerbating IPV perpetration in men and Factor 1 traits playing a unique role in mutual violence in women. These findings add to the literature on female psychopathy and have important implications for future research on gender and IPV. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

Examination of genetic variation in GABRA2 with conduct disorder and alcohol abuse and dependence in a longitudinal study

Previous studies have shown associations between single nucleotide polymorphisms (SNPs) in gamma aminobutyric acid receptor alpha 2 (GABRA2) and adolescent conduct disorder (CD) and alcohol dependence in adulthood, but not adolescent alcohol dependence. The present study was intended as a replication and extension of this work, focusing on adolescent CD, adolescent alcohol abuse and dependence (AAD), and adult AAD. Family based association tests were run using Hispanics and non-Hispanic European American subjects from two independent longitudinal samples. Although the analysis provided nominal support for an association with rs9291283 and AAD in adulthood and CD in adolescence, the current study failed to replicate previous associations between two well replicated GABRA2 SNPs and CD and alcohol dependence. Overall, these results emphasize the utility of including an independent replication sample in the study design, so that the results from an individual sample can be weighted in the context of its reproducibility.

Smoking behavior characteristics of non-selected smokers with childhood attention-deficit/hyperactivity disorder (AD/HD) history: a systematic review and meta-analysis

It is unclear whether adult smokers with childhood attention-deficit/hyperactivity disorder history (CH) have more severe smoking behavior than non-CH smokers, while it is clearly suggested that CH adolescents have more severe smoking behavior than CH adolescents. The aim of the present comprehensive meta-analysis is to determine whether CH smokers have more severe smoking behavior characteristics than those without and the effect of age on the association between CH and smoking behavior. We included all case-control studies and first round data collection of observational studies addressing the difference in smoking behavior characteristics of CH smokers versus non-CH smokers, with validated scales or structured interviews, without any language or date restriction. Nine studies (including 365 smokers with CH and 1,708 smokers without) were included. Compared to non-CH smokers, CH smokers smoked significantly more cigarettes [standardized mean differences (SMD) = 0.15, 95 % CI 0.01-0.28, p = 0.04] and began to regularly smoke earlier (SMD = -0.28, 95 % CI -0.49; -0.07, p = 0.01) but were not significantly more nicotine dependent (SMD = 0.23, 95 % CI -0.04 to 0.48, p = 0.08). After removing the single adolescent study, the significant association between CH and number of daily smoked cigarettes disappeared, and subgroups analyses confirmed that the significant association between CH and number of daily smoked cigarettes disappeared as age increased. Our meta-analysis illustrates a clinically important link between CH and tobacco smoking in adolescence but not later in life. Further high-quality studies are needed to confirm this finding, as only two studies included participants with a mean age below 20 years.

Implications of marijuana legalization for adolescent substance use

Marijuana that is legally available for adults has multiple implications for adolescent substance use. One potential effect that legalization may have is an increase in adolescent use to due increased availability, greater social acceptance, and possibly lower prices. Legalization may also facilitate the introduction of new formulations of marijuana (edible, vaporized) and with potentially higher potencies. It is unknown what adolescent consumption patterns will be if marijuana is widely available and marketed in different forms, or what effects different patterns of adolescent use will have on cognition, the development of marijuana use disorders, school performance, and the development of psychotic illnesses. Also unclear is whether adolescent users will be experiencing higher levels of tetrahydrocannabinol (THC) compared with previous generations of users due to higher potencies. Although previous studies of the effects of adolescent marijuana use provide some guidance for current policy and public health recommendations, many new studies will be needed that answer questions in the context of use within a legal adult environment. Claims that marijuana has medicinal benefits create additional challenges for adolescent prevention efforts, as they contrast with messages of its harmfulness. Prevention and treatment approaches will need to address perceptions of the safety of marijuana, claims of its medicinal use, and consider family-wide effects as older siblings and parents may increasingly openly consume and advocate for marijuana use. Guidance for primary care physicians will be needed regarded screening and counseling. Widespread legalization and acceptance of marijuana implies that as law enforcement approaches for marijuana control decline, public health, medical, and scientific efforts to understand and reduce negative consequences of adolescent marijuana use need to be substantially increased to levels commensurate with those efforts for tobacco and alcohol.