Implications of genetic epidemiology for the prevention of substance use disorders

Exploring perceptions of genetic risk and the transmission of substance use disorders

BACKGROUND

Substance use disorders (SUDs) have been consistently shown to exhibit moderate intergenerational continuity (1-3). While much research has examined genetic and social influences on addiction, less attention has been paid to clients' and lay persons' perceptions of genetic influences on the heritability of SUD (4) and implications for treatment.

METHODS

For this qualitative study, twenty-six structured Working Model of the Child Interviews (WMCI) were conducted with mothers receiving inpatient SUD treatment. These interviews were thematically analyzed for themes related to maternal perceptions around intergenerational transmission of substance use behaviours.

RESULTS

Findings show that over half of the mothers in this sample were preoccupied with their children's risk factors for addictions. Among this group, 29% spontaneously expressed concerns about their children's genetic risk for addiction, 54% shared worries about their children's propensity for addiction without mentioning the word gene or genetic. Additionally, 37% had challenges in even discussing their children's future when prompted. These concerns mapped onto internal working models of attachment in unexpected ways, with parents who were coded with balanced working models being more likely to discuss intergenerational risk factors and parents with disengaged working models displaying difficulties in discussing their child's future.

CONCLUSION

This research suggests that the dominant discourse around the brain-disease model of addictions, in its effort to reduce stigma and self-blame, may have unintended downstream consequences for parents' mental models about their children's risks for future addiction. Parents receiving SUD treatment, and the staff who deliver it, may benefit from psychoeducation about the intergenerational transmission of SUD as part of treatment.

Cocaine-Induced Locomotor Activation Differs Across Inbred Mouse Substrains

Cocaine use disorders (CUD) are devastating for affected individuals and impose a significant societal burden, but there are currently no FDA-approved therapies. The development of novel and effective treatments has been hindered by substantial gaps in our knowledge about the etiology of these disorders. The risk for developing a CUD is influenced by genetics, the environment and complex interactions between the two. Identifying specific genes and environmental risk factors that increase CUD risk would provide an avenue for the development of novel treatments. Rodent models of addiction-relevant behaviors have been a valuable tool for studying the genetics of behavioral responses to drugs of abuse. Traditional genetic mapping using genetically and phenotypically divergent inbred mice has been successful in identifying numerous chromosomal regions that influence addiction-relevant behaviors, but these strategies rarely result in identification of the causal gene or genetic variant. To overcome this challenge, reduced complexity crosses (RCC) between closely related inbred mouse strains have been proposed as a method for rapidly identifying and validating functional variants. The RCC approach is dependent on identifying phenotypic differences between substrains. To date, however, the study of addiction-relevant behaviors has been limited to very few sets of substrains, mostly comprising the C57BL/6 lineage. The present study expands upon the current literature to assess cocaine-induced locomotor activation in 20 inbred mouse substrains representing six inbred strain lineages (A/J, BALB/c, FVB/N, C3H/He, DBA/2 and NOD) that were either bred in-house or supplied directly by a commercial vendor. To our knowledge, we are the first to identify significant differences in cocaine-induced locomotor response in several of these inbred substrains. The identification of substrain differences allows for the initiation of RCC populations to more rapidly identify specific genetic variants associated with acute cocaine response. The observation of behavioral profiles that differ between mice generated in-house and those that are vendor-supplied also presents an opportunity to investigate the influence of environmental factors on cocaine-induced locomotor activity.

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.

All in the family: parental substance misuse, harsh parenting, and youth substance misuse among juvenile justice-involved youth

PURPOSE

Research consistently connects parental and youth substance misuse, yet less is known about the mechanisms driving this association among justice-involved youth. We examine whether harsh parenting is an explanatory mechanism for the association between parental substance use and parental mental health and youth substance use disorder in a sample of justice-involved youth.

METHODS

Data were drawn from the Northwestern Juvenile Project, a large-scale longitudinal survey of mental health and substance misuse in a representative sample of youth in juvenile detention. Harsh parenting, child maltreatment, youth alcohol and cannabis use disorder, and parental substance misuse and mental health were assessed among 1,825 detained youth (35.95% female) at baseline, three-year follow-up, and four-year follow-up.

RESULTS

At baseline, over 80% of youth used alcohol and/or cannabis; at the four-year follow-up, 16.35% and 19.69% of the youth were diagnosed with alcohol and cannabis use disorder, respectively. More than 20% of youth reported their parent misused substances and 6.11% reported a parent had a severe mental health need. Black youth experienced significantly fewer types of harsh parenting compared to White youth. Multivariate path analyses revealed harsh parenting mediated the association between parental substance misuse and mental health on youth alcohol and cannabis use disorder. Harsh parenting that does not rise to the level of child maltreatment mediated the association between parental substance misuse and mental health on youth alcohol use disorder; in contrast, child maltreatment did not mediate these associations. Multigroup analyses revealed the effect of harsh parenting on youth alcohol and cannabis use disorder did not vary across sex or race-ethnic subgroups.

CONCLUSIONS

Harsh parenting represents one mechanism for the intergenerational continuity of alcohol and cannabis misuse and should be regularly assessed for and addressed in juvenile justice settings.

Detection of altered methylation of MB-COMT promotor and DRD2 gene in cannabinoid or synthetic cannabinoid use disorder regarding gene variants and clinical parameters

This study aims to investigate the association between cannabinoid use disorder (CUD) or synthetic cannabinoid use disorder (SCUD) and methylation status of MB-COMT (membrane-bound catechol-O-methyltransferase) promotor or DRD2 gene considering gene variants and clinical parameters. Based on the DSM-5 criteria, 218 CUD/SCUD patients' diagnoses were confirmed with a positive urine test, and a control group consisting of 102 participants without substance use disorders was included. Methylation-specific PCR was used to identify the methylation of the MB-COMT promotor and DRD2 gene. DRD2-141C Ins/Del and COMT Val158Met gene variants were evaluated by using PCR-RFLP. When the DRD2 and MB-COMT promoter methylation of CUD/SCUD patients were compared with the control group, there was a significant difference between the MB-COMT promoter methylation status of the two groups. When comparing DRD2 gene methylation due to clinical parameters and DRD2 genotype distribution in patients, the methylation status was significantly different between the groups due to the family history. Again, comparing the MB-COMT promotor methylation due to the COMT Val158Met genotype distribution and clinical parameters in patients, the MB-COMT promoter methylation status was significantly different between the groups due to the presence of alcohol usage. In summary, whereas the MB-COMT promoter methylation may be associated with the CUD/SCUD, the methylation of the DRD2 gene was not related to CUD/SCUD.

A longitudinal study of personality traits, anxiety, and depressive disorders in young adults

BACKGROUND

How personality traits, anxiety, and depressive disorders relate longitudinally has implications for etiologic research and prevention. We sought to determine how neuroticism and extraversion relate to first-onset anxiety and depressive disorders in young adults.

DESIGN

An inception cohort of 489 university freshmen was followed for 6 years.

METHOD

Participants self-reported personality traits using the Eysenck Personality Questionnaire. Anxiety and depressive disorders were assessed using the Diagnostic Interview Schedule.

RESULTS

Baseline neuroticism predicted first-onset panic disorder, agoraphobia, generalized anxiety disorder (GAD), and major depressive disorder (MDD), while introversion predicted first-onset agoraphobia (moderate-large effects). Participants who developed panic disorder, agoraphobia, GAD, or MDD had increases in neuroticism if the disorder was current at follow-up (moderate-large effects). Participants who developed MDD but were in remission by follow-up had a moderate increase in neuroticism.

CONCLUSIONS

High neuroticism in young adulthood is either a true risk factor, or marker of risk, for first-onset anxiety and depressive disorders, as is low extraversion for agoraphobia. The current data suggest large neuroticism "state" effects for panic disorder, agoraphobia, and MDD, and moderate "scar" effects from MDD. Though many clinicians and researchers regard personality traits simply as "vulnerability" factors, longitudinal analyses suggest additional complexity.

Ankyrin Repeat and Kinase Domain Containing 1 Gene, and Addiction Vulnerability

The TaqIA single nucleotide variant (SNV) has been tested for association with addictions in a huge number of studies. TaqIA is located in the ankyrin repeat and kinase domain containing 1 gene (ANKK1) that codes for a receptor interacting protein kinase. ANKK1 maps on the NTAD cluster along with the dopamine receptor D2 (DRD2), the tetratricopeptide repeat domain 12 (TTC12) and the neural cell adhesion molecule 1 (NCAM1) genes. The four genes have been associated with addictions, although TTC12 and ANKK1 showed the strongest associations. In silico and in vitro studies revealed that ANKK1 is functionally related to the dopaminergic system, in particular with DRD2. In antisocial alcoholism, epistasis between ANKK1 TaqIA and DRD2 C957T SNVs has been described. This clinical finding has been supported by the study of ANKK1 expression in peripheral blood mononuclear cells of alcoholic patients and controls. Regarding the ANKK1 protein, there is direct evidence of its location in adult and developing central nervous system. Together, these findings of the ANKK1 gene and its protein suggest that the TaqIA SNV is a marker of brain differences, both in structure and in dopaminergic function, that increase individual risk to addiction development.

Addiction resistance to alcohol: What about heavy drinkers who avoid alcohol problems?

BACKGROUND

Some individuals are resistant to alcohol use disorders despite high levels of intake. Addiction Resistance (AR) measures the disparity between alcohol consumption and alcohol use disorder (AUD) symptoms, such that some persons exhibit few (AUD) symptoms despite higher intake. The validity of the concept and the factors contributing to AR are not well understood. The aim of this study was to predict AR based on variables related to risk for addiction that are measured in the Family Health Patterns Project.

METHOD

Participants were healthy young adults (n = 1122) with and without a family history of alcohol and other substance use disorders who were given measures of mood stability and risk-taking tendencies, and were interviewed to determine alcohol intake, AUD symptoms, and other substance use disorders (SUD). AR was calculated using maximal lifetime alcohol intake and number of AUD symptoms.

RESULTS

A principal components analysis was run with varimax rotation, which yielded three components: Component 1 indexed behavioral and mood regulation, Component 2 encompassed family and environmental factors, and Component 3 included cognitive factors. A multiple regression analysis revealed that Component 1 and Component 2 were predictive of AR whereas Component 3 was not.

DISCUSSION

Individuals who reported greater emotional stability, norm adherence, risk avoidance, and fewer family members with substance use disorders were more resistant to AUD despite higher alcohol intake. These findings suggest that AUD risk and resistance may represent different points of the same continuum.

The Neuroscience of Drug Reward and Addiction

Drug consumption is driven by a drug's pharmacological effects, which are experienced as rewarding, and is influenced by genetic, developmental, and psychosocial factors that mediate drug accessibility, norms, and social support systems or lack thereof. The reinforcing effects of drugs mostly depend on dopamine signaling in the nucleus accumbens, and chronic drug exposure triggers glutamatergic-mediated neuroadaptations in dopamine striato-thalamo-cortical (predominantly in prefrontal cortical regions including orbitofrontal cortex and anterior cingulate cortex) and limbic pathways (amygdala and hippocampus) that, in vulnerable individuals, can result in addiction. In parallel, changes in the extended amygdala result in negative emotional states that perpetuate drug taking as an attempt to temporarily alleviate them. Counterintuitively, in the addicted person, the actual drug consumption is associated with an attenuated dopamine increase in brain reward regions, which might contribute to drug-taking behavior to compensate for the difference between the magnitude of the expected reward triggered by the conditioning to drug cues and the actual experience of it. Combined, these effects result in an enhanced motivation to "seek the drug" (energized by dopamine increases triggered by drug cues) and an impaired prefrontal top-down self-regulation that favors compulsive drug-taking against the backdrop of negative emotionality and an enhanced interoceptive awareness of "drug hunger." Treatment interventions intended to reverse these neuroadaptations show promise as therapeutic approaches for addiction.

Genetic Markers in Psychiatry

Psychiatric disorders such as addiction (substance use and addictive disorders), depression, eating disorders, schizophrenia, and post-traumatic stress disorder (PTSD) are severe, complex, multifactorial mental disorders that carry a high social impact, enormous public health costs, and various comorbidities as well as premature morbidity. Their neurobiological foundation is still not clear. Therefore, it is difficult to uncover new set of genes and possible genetic markers of these disorders since the understanding of the molecular imbalance leading to these disorders is not complete. The integrative approach is needed which will combine genomics and epigenomics; evaluate epigenetic influence on genes and their influence on neuropeptides, neurotransmitters, and hormones; examine gene × gene and gene × environment interplay; and identify abnormalities contributing to development of these disorders. Therefore, novel genetic approaches based on systems biology focused on improvement of the identification of the biological underpinnings might offer genetic markers of addiction, depression, eating disorders, schizophrenia, and PTSD. These markers might be used for early prediction, detection of the risk to develop these disorders, novel subtypes of the diseases and tailored, personalized approach to therapy.

Resilience to Risk for Psychopathology: The Role of White Matter Microstructural Development in Adolescence

BACKGROUND

One major risk factor for the development of psychopathology is a family history of psychopathology (FHP). Cross-sectional studies have shown that FHP is associated with alterations in white matter microstructure in adolescents without current psychopathology; however, whether these associations persist throughout adolescence, particularly in those who remain resilient to developing psychopathology, is unclear.

METHODS

Sixty-six adolescents underwent diffusion-weighted imaging at baseline (12-16 years of age) and at one or two follow-up visits (142 total scans). Adolescents' parents completed a modified Family History Assessment Module to calculate FHP density (FHPD) based on familial alcohol use, substance use, and major depressive, generalized anxiety, substance-induced mood, and antisocial personality disorders. The relationship between FHPD and white matter microstructural development was examined using multilevel modeling.

RESULTS

FHPD was associated with significant alterations in white matter microstructure at baseline; in the bilateral superior corona radiata and left superior longitudinal fasciculus, these effects were transient (FHPD was associated with altered white matter microstructure only in early adolescence), while effects in the posterior limb of the internal capsule were persistent. Associations between FHPD and white matter microstructure in the body of the corpus callosum emerged later in adolescence.

CONCLUSIONS

This prospective, longitudinal study provides novel information indicating that the association between FHP and white matter microstructure previously observed in adolescents is transient in most regions but may persist into late adolescence in other regions, despite current resilience to developing psychopathology. Future studies are necessary to determine if these persistent alterations are associated with onset of psychopathology later in life.

Environmental, genetic and epigenetic contributions to cocaine addiction

Decades of research on cocaine has produced volumes of data that have answered many important questions about the nature of this highly addictive drug. Sadly, none of this information has translated into the development of effective therapies for the treatment of cocaine addiction. This review endeavors to assess the current state of cocaine research in an attempt to identify novel pathways for therapeutic development. For example, risk of cocaine addiction is highly heritable but genome-wide analyses comparing cocaine-dependent individuals to controls have not resulted in promising targets for drug development. Is this because the genetics of addiction is too complex or because the existing research methodologies are inadequate? Likewise, animal studies have revealed dozens of enduring changes in gene expression following prolonged exposure to cocaine, none of which have translated into therapeutics either because the resulting compounds were ineffective or produced intolerable side-effects. Recently, attention has focused on epigenetic modifications resulting from repeated cocaine intake, some of which appear to be heritable through changes in the germline. While epigenetic changes represent new vistas for therapeutic development, selective manipulation of epigenetic marks is currently challenging even in animals such that translational potential is a distant prospect. This review will reveal that despite the enormous progress made in understanding the molecular and physiological bases of cocaine addiction, there is much that remains a mystery. Continued advances in genetics and molecular biology hold potential for revealing multiple pathways toward the development of treatments for the continuing scourge of cocaine addiction.

Neuroepigenetics and addiction

Drug addiction involves long-term behavioral abnormalities that arise in response to repeated exposure to drugs of abuse in vulnerable individuals. It is a multifactorial syndrome involving a complex interplay between genes and the environment. Evidence suggests that the underlying mechanisms regulating these persistent behavioral abnormalities involve changes in gene expression throughout the brain's reward circuitry, in particular, in the mesolimbic dopamine system. In the past decade, investigations have begun to reveal potential genes involved in the risk for addiction through genomewide association studies. Additionally, a crucial role for epigenetic mechanisms, which mediate the enduring effects of drugs of abuse on the brain in animal models of addiction, has been established. This chapter focuses on recent evidence that genetic and epigenetic regulatory events underlie the changes throughout the reward circuitry in humans, as well as animal models of addiction. While further investigations are necessary, a picture of genetic and epigenetic mechanisms involved in addiction is beginning to emerge and the insight gained from these studies will be key to the identification of novel targets for improved diagnosis and treatment of addiction syndromes in humans.

Spatial Analysis Methods for Health Promotion and Education

This article provides a review of spatial analysis methods for use in health promotion and education research and practice. Spatial analysis seeks to describe or make inference about variables with respect to the places they occur. This includes geographic differences, proximity issues, and access to resources. This is important for understanding how health outcomes differ from place to place; and in terms of understanding some of the environmental underpinnings of health outcomes data by placing it in context of geographic location. This article seeks to promote spatial analysis as a viable tool for health promotion and education research and practice. Four more commonly used spatial analysis techniques are described in-text. An illustrative example of motor vehicle collisions in a large metropolitan city is presented using these techniques. The techniques discussed are as follows: descriptive mapping, global spatial autocorrelation, cluster detection, and identification and spatial regression analysis. This article provides useful information for health promotion and education researchers and practitioners seeking to examine research questions from a spatial perspective.

Etiology of drug abuse: a narrative analysis

Introduction and Aim. Further gains in the prevention of drug abuse disorders require in-depth and holistic understanding of the risk factors of addiction from different perspectives. Lay persons and experts have different concepts of risk which could complement each other. The purpose of this study was to elaborate drug abuse risk factors through the story of individuals who had become drug dependent. Design and Methods. In this qualitative research, 33 individuals attending treatment centres for drug abuse were interviewed about the story of their addiction in Kerman, Iran. Interview questions were around the story of the participants. Results. All participants were male and in the age range of 18–40 years. Narrative analysis identified five themes as the main risk factors: family factors, peer pressure, the effect of gateway drugs (especially waterpipe), individual characteristics, and the community factors. More emphasis was placed upon the role of family factors, peer influence, and gateway effect. Discussion and Conclusion. This study elicited information from drug dependent subjects regarding the risk factors of drug abuse. According to drug dependent individuals' views, more attention should be devoted to family and peer influences by policy makers, in developing culture-based preventive strategies.

On the interaction between drugs of abuse and adolescent social behavior

RATIONALE

Social factors influence drug abuse. Conversely, drugs of abuse alter social behavior. This is especially pertinent during post-weaning development, when there are profound changes in the social repertoire, and the sensitivity to the positive and negative effects of drugs of abuse is altered.

OBJECTIVES

This study aimed to provide an overview of our current understanding of the interaction between drugs of abuse and juvenile/adolescent social behavior.

METHODS

We first provide evidence that a characteristic form of juvenile and adolescent social behavior, i.e., social play behavior, has reinforcing properties and is affected by drugs of abuse. Next, social risk factors for drug use and addiction are described, including antisocial personality traits and early social insults. Last, we discuss research that investigates social influences on drug use, as well as the consequences of perinatal drug exposure on later social interactions.

RESULTS

Social play behavior is highly rewarding in laboratory animals, and it is affected by low doses of opioids, cannabinoids, ethanol, nicotine, and psychostimulants. In humans, antisocial personality traits, most prominently in the form of conduct disorder, are a prominent risk factor for drug addiction. Preclinical studies have consistently shown altered sensitivity to drugs as a result of social isolation during post-weaning development. The social environment of an individual has a profound, but complex, influence on drug use, and perinatal drug exposure markedly alters later social interactions.

CONCLUSIONS

The studies reviewed here provide a framework to understand the interaction between drugs of abuse and adolescent social interaction, at the preclinical and the clinical level.

Diagnostic transitions from childhood to adolescence to early adulthood

BACKGROUND

Quantifying diagnostic transitions across development is needed to estimate the long-term burden of mental illness. This study estimated patterns of diagnostic transitions from childhood to adolescence and from adolescence to early adulthood.

METHODS

Patterns of diagnostic transitions were estimated using data from three prospective, longitudinal studies involving close to 20,000 observations of 3,722 participants followed across multiple developmental periods covering ages 9-30. Common DSM psychiatric disorders were assessed in childhood (ages 9-12; two samples), adolescence (ages 13-18; three samples), and early adulthood (ages 19 to age 32; three samples) with structured psychiatric interviews and questionnaires.

RESULTS

Having a disorder at an early period was associated with at least a threefold increase in odds for having a disorder at a later period. Homotypic and heterotypic transitions were observed for every disorder category. The strongest evidence of continuity was seen for behavioral disorders (particularly ADHD) with less evidence for emotional disorders such as depression and anxiety. Limited evidence was found in adjusted models for behavioral disorders predicting later emotional disorders. Adult substance disorders were preceded by behavioral disorders, but not anxiety or depression.

CONCLUSIONS

Having a disorder in childhood or adolescence is a potent risk factor for a range of psychiatric problems later in development. These findings provide further support for prevention and early life intervention efforts and suggest that treatment at younger ages, while justified in its own right, may also have potential to reduce the risk for disorders later in development.

The genetics of alcohol dependence

Alcohol consumption dates back to the Neolithic period, and alcohol dependence contributes substantially to the current global burden of disease. Despite this, optimal therapies and preventive strategies are lacking. Formal genetic studies of alcohol dependence have shown that genetic factors play as large a role in disease etiology as environmental factors. Molecular genetic studies may identify causal factors and facilitate the development of novel preventive and therapeutic approaches. Whereas earlier studies involved the use of linkage- and candidate-gene approaches, recent years have witnessed the introduction of genome-wide association studies (GWAS). The present review provides a brief overview of the findings of formal genetic studies, summarizes the results of earlier molecular-genetic investigations, and presents a detailed overview of all published GWAS in the field of alcohol dependence research. To date, few genome-wide significant findings have been reported. However, through the polygenic approach, GWAS have both confirmed the existence of a multitude of novel risk genes and indicated interesting new candidates.

The genetic basis of addictive disorders

Addictions are common, chronic, and relapsing diseases that develop through a multistep process. The impact of addictions on morbidity and mortality is high worldwide. Twin studies have shown that the heritability of addictions ranges from 0.39 (hallucinogens) to 0.72 (cocaine). Twin studies indicate that genes influence each stage from initiation to addiction, although the genetic determinants may differ. Addictions are by definition the result of gene × environment interaction. These disorders, which are in part volitional, in part inborn, and in part determined by environmental experience, pose the full range of medical, genetic, policy, and moral challenges. Gene discovery is being facilitated by a variety of powerful approaches, but is in its infancy. It is not surprising that the genes discovered so far act in a variety of ways: via altered metabolism of drug (the alcohol and nicotine metabolic gene variants), via altered function of a drug receptor (the nicotinic receptor, which may alter affinity for nicotine but as discussed may also alter circuitry of reward), and via general mechanisms of addiction (genes such as monoamine oxidase A and the serotonin transporter that modulate stress response, emotion, and behavioral control). Addiction medicine today benefits from genetic studies that buttress the case for a neurobiologic origin of addictive behavior, and some general information on familially transmitted propensity that can be used to guide prevention. A few well-validated, specific predictors such as OPRM1, ADH1B, ALDH2, CHRNA5, and CYP26 have been identified and can provide some specific guidance, for example, to understand alcohol-related flushing and upper GI cancer risk (ADH1B and AKLDH2), variation in nicotine metabolism (CYP26), and, potentially, naltrexone treatment response (OPRM1). However, the genetic predictors available are few in number and account for only a small portion of the genetic variance in liability, and have not been integrated into clinical nosology or care.

Epidemiology of substance use disorders

Epidemiological studies of substance use and substance use disorders (SUDs) have provided an abundance of data on the patterns of substance use in nationally representative samples across the world (Degenhardt et al. in PLoS Med 5(7):e141, 2008; Johnston et al. in Monitoring the future national survey results on drug use, 1975-2010, vol I, secondary school students. Institute for Social Research, Ann Arbor, MI, 2011; SAMHSA in Results from the 2010 national survey on drug use and health: summary of national findings, vol NSDUH, series H-41, HHS Publication No. (SMA) 11-4658. Substance Abuse and Mental Health Services Administration, Rockville, 2011). This paper presents a summary of the goals, methods, and recent findings on the epidemiology of substance use and disorders in the general population of adults and adolescents and describes the methods and findings on the genetic epidemiology of drug use disorders. The high 12-month prevalence rates of substance dependence in US adults (about 12 % for alcohol and 2-3 % for illicit drugs) approximate those of other mental disorders as well as chronic physical disorders with major public health impact. New findings from the nationally representative samples of US youth reveal that the lifetime prevalence of alcohol use disorders is approximately 8 % and illicit drug use disorders is 2-3 % (Merikangas et al. in J Am Acad Child Adolesc Psychiatry 49(10):980-989, 2010; Swendsen et al. in Arch Gen Psychiatry 69(4):390-398, 2012; SAMHSA in Results from the 2010 national survey on drug use and health: summary of national findings, vol NSDUH, Series H-41, HHS Publication No. (SMA) 11-4658. Substance Abuse and Mental Health Services Administration, Rockville, 2011). The striking increase in prevalence rates from ages 13 to 18 highlight adolescence as the key period of development of SUDs. The application of genetic epidemiological studies has consistently demonstrated that genetic factors have a major influence on progression of substance use to dependence, whereas environmental factors unique to the individual play an important role in exposure and initial use of substances. Identification of specific susceptibility genes and environmental factors that influence exposure and progression of drug use may enhance our ability to prevent and treat SUDs.

Parental substance use impairment, parenting and substance use disorder risk

Using data from a nationally representative sample, this study investigated substance use disorder (SUD) among respondents with ages 15-54 years as a function of their parents' substance-related impairment and parents' treatment history. In addition, associations among maternal and paternal substance-related impairment, specific parenting behaviors, and risk for SUD in the proband were examined. As expected, parental substance-related impairment was associated with SUD. Paternal treatment history was associated with a decreased risk for SUD in the proband but did not appear to be associated with positive parenting practices. Results of post hoc analyses suggested that parenting behaviors might operate differently to influence SUD risk in children where parents are affected by substance use problems compared with nonaffected families. Future research is warranted to better understand the complex relationships among parental substance use, treatment, parenting behaviors, and SUD risk in offspring. Opportunities might exist within treatment settings to improve parenting skills.

Sex hormone activity in alcohol addiction: integrating organizational and activational effects

There are well-known sex differences in the epidemiology and etiopathology of alcohol dependence. Male gender is a crucial risk factor for the onset of alcohol addiction. A directly modifying role of testosterone in alcohol addiction-related behavior is well established. Sex hormones exert both permanent (organizational) and transient (activational) effects on the human brain. The sensitive period for these effects lasts throughout life. In this article, we present a novel early sex hormone activity model of alcohol addiction. We propose that early exposure to sex hormones triggers structural (organizational) neuroadaptations. These neuroadaptations affect cellular and behavioral responses to adult sex hormones, sensitize the brain's reward system to the reinforcing properties of alcohol and modulate alcohol addictive behavior later in life. This review outlines clinical findings related to the early sex hormone activity model of alcohol addiction (handedness, the second-to-fourth-finger length ratio, and the androgen receptor and aromatase) and includes clinical and preclinical literature regarding the activational effects of sex hormones in alcohol drinking behavior. Furthermore, we discuss the role of the hypothalamic-pituitary-adrenal and -gonadal axes and the opioid system in mediating the relationship between sex hormone activity and alcohol dependence. We conclude that a combination of exposure to sex hormones in utero and during early development contributes to the risk of alcohol addiction later in life. The early sex hormone activity model of alcohol addiction may prove to be a valuable tool in the development of preventive and therapeutic strategies.

Understanding genetic risk for substance use and addiction: a guide for non-geneticists

There is considerable enthusiasm for the potential of genetics research for prevention and treatment of addiction and other mental disorders. As a result, clinicians are increasingly exposed to issues of genetics that are fairly complex, and for which they may not have been adequately prepared by their training. Studies suggest that the heritability of substance use disorders is approximately 0.5. Others report that family members of affected individuals experience a 4- to 8-fold increased risk of disorder themselves. Statements that addiction is "50% genetic" in origin may be taken by some to imply one's chances of developing the disorder, or that a lack of a positive family history confers immunity. In fact, such conclusions are inaccurate, their implications unwarranted given the true meaning of heritability. Through a review of basic concepts in genetic epidemiology, we attempt to demystify these estimates of risk and situate them within the broader context of addiction. Methods of inferring population genetic variance and individual familial risk are examined, with a focus on their practical application and limitations. An accurate conceptualization of addiction necessitates an approach that transcends specific disciplines, making a basic awareness of the perspectives of disparate specialties key to furthering progress in the field.

Risky decision making in substance dependent adolescents with a disruptive behavior disorder

Of all psychiatric disorders, the disruptive behavior disorders (DBDs) are the most likely to predispose to substance dependence (SD). One possible underlying mechanism for this increased vulnerability is risky decision making. The aim of this study was to examine decision making in DBD adolescents with and without SD. Twenty-five DBD adolescents (19 males) with SD (DBD+SD), 28 DBD adolescents (23 males) without SD (DBD-SD) and 99 healthy controls (72 males) were included in the study. DBD adolescents with co-morbid attention deficit/ hyperactivity disorder (ADHD) were excluded. Risky decision making was investigated by assessing the number of disadvantageous choices in the Iowa gambling task. DBD+SD made significantly more risky choices than healthy controls and DBD-SD. Healthy controls and DBD-SD did not differ on risky decision making. These results suggest that risky decision making is a vulnerability factor for the development of SD in a subgroup of adolescents with DBD without ADHD.

Psychopathology in offspring from families of alcohol dependent female probands: a prospective study

BACKGROUND

Despite the importance of understanding the long-term outcome for children of alcohol dependent (AD) women, the available literature is largely based on offspring of AD fathers and few have utilized prospective designs that include child, adolescent and young adult assessments. Multiplex AD families in which multiple cases of AD are present provide an ideal setting for understanding developmental variants of the adult phenotype.

METHOD

Offspring from multiplex AD families identified through the mother or control families were evaluated multiple times during childhood and followed to young adulthood. Familial risk status and the presence of specific child/adolescent disorders were used as predictors of substance use disorder outcome by young adulthood.

RESULTS

Offspring who were members of maternal multiplex families had elevated rates of child and young adulthood disorders. High risk offspring of alcohol dependent women were at increased risk for externalizing (Conduct Disorder and ADHD) and internalizing disorders (Major Depressive Disorder (MDD) and Anxiety Disorders). By young adulthood, offspring from these multiplex families had significantly greater odds of developing alcohol abuse or dependence (odds ratio [OR] = 3.63 [CI 1.36-9.64]) and drug abuse or dependence (OR = 4.23 [CI 1.73-10.32]). The prospective design of the study revealed that specific childhood disorders (Conduct Disorder, ADHD, MDD) increased the odds of subsequent development of substance use disorder (SUD).

CONCLUSIONS

Multiplex familial risk for alcohol dependence is a significant predictor of substance use disorders by young adulthood. Familial risk and an earlier childhood disorder may set the stage for later development of SUD.

Co-occurrence of ODD and Anxiety: Shared Risk Processes and Evidence for a Dual-Pathway Model

Although oppositional defiant disorder (ODD) and anxiety disorders (ADs) often co-occur, the literature is mixed regarding the effects of such co-occurrence. For example, there is evidence that AD symptoms may mitigate ODD symptoms (buffer hypothesis) or exacerbate ODD symptoms (multiple problem hypothesis). A dual-pathway model incorporates previous research and addresses both hypotheses. We describe several possible etiological or risk processes that may underlie each of these ODD-AD pathways, including child temperament, aggression, limbic system processes, executive functioning abilities, and social information-processing biases, and suggest an integrated model. We conclude with implications for the model and directions for future research involving co-occurring ODD and ADs.

Measuring addiction propensity and severity: the need for a new instrument

Drug addiction research requires but lacks a valid and reliable way to measure both the risk (propensity) to develop addiction and the severity of manifest addiction. This paper argues for a new measurement approach and instrument to quantify propensity to and severity of addiction, based on the testable assumption that these constructs can be mapped onto the same dimension of liability to addiction. The case for this new direction becomes clear from a critical review of empirical data and the current instrumentation. The many assessment instruments in use today have proven utility, reliability, and validity, but they are of limited use for evaluating individual differences in propensity and severity. The conceptual and methodological shortcomings of instruments currently used in research and clinical practice can be overcome through the use of new technologies to develop a reliable, valid, and standardized assessment instrument(s) to measure and distinguish individual variations in expression of the underlying latent trait(s) that comprises propensity to and severity of drug addiction. Such instrumentation would enhance our capacity for drug addiction research on linkages and interactions among familial, genetic, psychosocial, and neurobiological factors associated with variations in propensity and severity. It would lead to new opportunities in substance abuse prevention, treatment, and services research, as well as in interventions and implementation science for drug addiction.

Association of adolescent symptoms of depression and anxiety with daily smoking and nicotine dependence in young adulthood: findings from a 10-year longitudinal study

AIMS

To examine the association of adolescent depression and anxiety symptoms with daily smoking and nicotine dependence in young adulthood.

DESIGN

A prospective cohort study of adolescent and young adult health (n = 1943). Teen assessments occurred at 6-monthly intervals, with two follow-up assessments in young adulthood (wave 7, 1998; wave 8, 2001-03).

SETTING

Victoria, Australia. Participants Students who participated at least once during the first six (adolescent) waves of the cohort study.

MEASUREMENTS

Adolescent depression and anxiety symptoms were assessed using the Revised Clinical Interview Schedule (CIS-R). Young adult tobacco use was defined as: daily use (6 or 7 days per week) and dependent use (> or =4 on the Fagerstrom Test for Nicotine Dependence).

FINDINGS

Among adolescent 'less than daily' smokers, those with high levels of depression and anxiety symptoms had an increased risk of reporting nicotine dependence in young adulthood [odds ratio (OR) 3.3, 95% confidence interval (CI) 1.2-9.1] compared to young adults who had low levels of adolescent depression and anxiety symptoms, after adjusting for potential confounding factors. Similarly, in the adjusted model (OR 1.9, 95% CI 1.0-3.4), among adolescent 'daily' smokers, those with high levels of depression and anxiety symptoms had an almost two-fold increase in the odds of reporting nicotine dependence in young adulthood compared to young adults with low levels of adolescent depression and anxiety symptoms.

CONCLUSIONS

Adolescent smokers with depression and anxiety symptoms are at increased risk for nicotine dependence into young adulthood. They warrant vigilance from primary care providers in relation to tobacco use well into adulthood.

Epidemiology of mental disorders in children and adolescents

This article provides a review of the magnitude of mental disorders in children and adolescents from recent community surveys across the world. Although there is substantial variation in the results depending upon the methodological characteristics of the studies, the findings converge in demonstrating that approximately one fourth of youth experience a mental disorder during the past year, and about one third across their lifetimes. Anxiety disorders are the most frequent conditions in children, followed by behavior disorders, mood disorders, and substance use disorders. Fewer than half of youth with current mental disorders receive mental health specialty treatment. However, those with the most severe disorders tend to receive mental health services. Current issues that are now being identified in the field of child psychiatric epidemiology include: refinement of classification and assessment, inclusion of young children in epidemiologic surveys, integration of child and adult psychiatric epidemiology, and evaluation of both mental and physical disorders in children.

Substance use and behaviour disorders in Puerto Rican youth: a migrant family study

BACKGROUND

Hispanics in the USA have higher rates of substance use disorders than similar ethnic groups residing in Latin American nations, and recent evidence suggests an increase in substance use among US Hispanic youth. This investigation examines the familial and societal correlates of this increase by comparing Puerto Rican families residing in the mainland USA and Puerto Rico.

METHODS

Using migrant and controlled family study methods, 279 probands in San Juan and 236 probands in New Haven were recruited from treatment clinics and the general community to compose four diagnostic groups: drug abuse/dependence; alcohol abuse/dependence; psychiatric controls; unaffected controls. 806 biological offspring aged 12-17 were then directly interviewed.

RESULTS

Total rates for alcohol use were greater among San Juan youth than their migrant counterparts. By contrast, US migrant adolescents were more likely to use cannabis. A strong association was observed between parental and child substance use at both sites, particularly for boys, and offspring of probands with drug use disorders were at greatest risk for substance use and related disorders. Familial aggregation patterns did not vary substantially by site.

CONCLUSIONS

Despite societal influences on the magnitude and patterns of substance use in migrant youth, the consistent influence of parental disorders across sites reveals that the cross-generational transmission of substance use disorders in prior studies extends to Hispanic families and is an important factor to consider in the development of prevention strategies.

Treatment-naive active alcoholics have greater psychiatric comorbidity than normal controls but less than treated abstinent alcoholics

BACKGROUND

Most alcoholism research in the U.S. uses convenience samples of treated alcoholics. The findings from treated samples have traditionally been applied to all alcoholics, including the 75% of alcoholics who are untreated. Improper generalization from select samples to an entire population is called 'Berkson's fallacy'. We compared untreated versus treated alcoholics, in order to ascertain whether both groups belonged to the same population with regard to psychiatric comorbidity.

METHODS

We compared psychiatric comorbidity in 1) active treatment-naive alcoholics (TNA; n=86) 2) treated long-term abstinent alcoholics (TAA; n=52) and 3) non-alcoholic controls (NAC;n=118). We examined lifetime and current diagnoses, lifetime symptom counts, and psychological measures in the anxiety, mood and externalizing disorder domains.

RESULTS

TNA did not differ from NAC in psychiatric diagnosis rates, were abnormal compared to NAC on all psychological measures, had more externalizing symptoms than NAC, and showed a strong trend for men to have more symptoms in the mood and anxiety domains. TAA compared to TNA had higher diagnosis rates (all domains), symptom counts (all domains), and psychological measures of deviance proneness, but were comparable to TNA on anxiety and mood psychological measures.

CONCLUSIONS

The abnormal thinking (psychological measures) in TNA (versus NAC) does not extend to behavior (symptoms) to the degree that it does in TAA. These results underline the importance of the use of subdiagnostic measures of psychiatric comorbidity in studies of alcoholics. The finding of lesser comorbidity in TNA versus TAA confirms the presence of Berkson's fallacy in generalizing from treated samples to all alcoholics.

Psychopathology in offspring from multiplex alcohol dependence families with and without parental alcohol dependence: a prospective study during childhood and adolescence

Multiplex families ascertained through multiple alcohol dependent individuals appear to transmit alcohol and drug use disorders at higher rates than randomly selected families of alcoholics. Our goal was to investigate the risk of developing specific psychiatric diagnoses during childhood or adolescence in association with familial risk status (high-risk [HR] or low-risk [LR]) and parental diagnosis. Using a prospective longitudinal design, HR offspring from three generation multiplex alcohol dependence families and LR control families were followed yearly. Data analysis was based on consensus diagnoses from 1738 yearly evaluations conducted with the offspring and a parent using the K-SADS, and separately modeled the effects of familial susceptibility and exposure to parental alcohol dependence. Multiplex family membership and parental alcohol and drug dependence significantly increased the odds that offspring would experience some form of psychopathology during childhood or adolescence, particularly externalizing disorders. Additionally, parental alcohol dependence increased the odds that adolescent offspring would have major depressive disorder (MDD). While it is well known that parental substance dependence is associated with externalizing psychopathology, the increased risk for MDD seen during adolescence in the present study suggests the need for greater vigilance of these children.

Co-occurring ODD and GAD symptom groups: source-specific syndromes and cross-informant comorbidity

Despite important clinical and nosological implications, the comorbidity of oppositional defiant disorder (ODD) and generalized anxiety disorder (GAD) has received little attention. A clinic-based sample of 243 boys (ages 6-10 years), their parents, and teachers participated in an evaluation that involved assessments of behavioral, academic, and family functioning. ODD and GAD symptom groups were defined using various combinations of mother and teacher reports. ODD symptom groups were associated with conduct disorder symptoms, and GAD symptom groups with major depressive disorder symptoms, regardless of rater. Attention deficit/hyperactivity disorder (ADHD) symptoms were associated with ODD and GAD symptom groups; however, covarying ADHD symptoms altered few findings. The ODD + GAD symptom groups were associated with higher rates of co-occurring symptoms and risk factors within (source-specific syndromes) and across (cross-informant comorbidity) informants.

Evidence for a two-stage model of dependence using the NESARC and its implications for genetic association studies

Some twin studies suggest that substance initiation and dependence are part of a complex, two-stage process and that some genetic influences are stage-specific, acting on either the transition from abstinence to initiation, or on the transition from use to dependence. However, questions remain about the two-stage model, especially for illicit drugs. Using a familial aggregation design, we tested the hypothesized two-stage model of dependence on illicit substances and alcohol in a large, nationally representative sample. Family history of drug or alcohol problems is significantly associated with initiation that does not progress to dependence (i.e., conditional initiation). Furthermore, family history of drug or alcohol problems is significantly associated with dependence even after conditioning on factors influencing initiation (i.e., conditional dependence). These results suggest that substance initiation and dependence involve at least partially distinct familial factors. The possibility that different genetic factors affect initiation and dependence has important implications for control group selection in case-control genetic association studies, and may explain some inconsistent results for drug dependence. If some genetic factors are stage-specific (i.e., not common across initiation and dependence), inclusion of abstainers in the control group may mix the genetic effects for initiation with those for transition to dependence, providing unclear results. Depending on the specific question about the nature of the genetic effect (whether on initiation, on dependence, or both), investigators designing case-control genetic association studies should carefully consider inclusion and exclusion criteria of the control group.

Under the influence of genetics: how transdisciplinarity leads us to rethink social pathways to illness

This article describes both sociological and genetic theories of illness causation and derives propositions expected under each and under a transdisciplinary theoretical frame. The authors draw propositions from three theories -- fundamental causes, social stress processes, and social safety net theories -- and tailor hypotheses to the case of alcohol dependence. Analyses of a later wave of the Collaborative Study on the Genetics of Alcoholism reveal a complex interplay of the GABRA2 gene with social structural factors to produce cases meeting DSM/ICD diagnoses. Only modest evidence suggests that genetic influence works through social conditions and experiences. Further, women are largely unaffected in their risk for alcohol dependence by allele status at this candidate gene; family support attenuates genetic influence; and childhood deprivation exacerbates genetic predispositions. These findings highlight the essential intradisciplinary tension in the role of proximal and distal influences in social processes and point to the promise of focusing directly on dynamic, networked sequences that produce different pathways to health and illness.

Smoking, drugs, and other behavioral health problems among multiethnic adolescents in the NHSDA

Data from the NHSDA (2000) which contained screening measures for assessing risk for DSM-IV psychiatric disorders, were used to estimate smoking prevalence and its association with these disorders, among European American, Hispanic, and African American adolescents. Prevalence estimates, odds ratios, and hazard models were used to compare ethnic subgroups. European American and Hispanic adolescents born in the U.S. had a higher prevalence of smoking and DSM-IV tobacco dependence, and girls were higher than boys. Lifetime smokers had statistically significant odds ratios for anxiety, affective, substance use, and any behavior disorder, while Current smokers had a similar risk pattern except anxiety disorder. The increased risk for substance use disorder among smokers was notably higher. A hazard analysis showed that early onset of smoking (before 12 years) was related to earlier illicit drug use initiation as contrasted with later onset (12 years +), and non-smoking sharply reduced risk and delayed initiation into drug use. African American and Hispanic immigrants had lower risk of smoking initiation and tobacco dependence, however, ethnic group adolescents who initiated smoking shared increased risk of addictive and non-addictive disorders.

Declining transition rate in ultra high risk (prodromal) services: dilution or reduction of risk?

There is growing interest in the prodromal stage of psychotic disorders, with many services now providing care for these "ultra high risk" (UHR) individuals. However, a reduction in the rate of transition to psychosis has been suspected over the last few years. This has implications for the use of interventions in this population and for the validity of research findings. This study examined the transition rate in one UHR service, the Personal Assessment and Crisis Evaluation Clinic, over the years 1995-2000 and investigated possible causes for the transition rate reduction. There was evidence for a declining transition rate, with each successive year showing a rate 0.80 times that of the preceding year. Functioning and symptom level were not responsible for the change. The decreased transition rate was partly explained by a reduction in the duration of symptoms of patients prior to receiving help. That is, UHR individuals are being detected and provided with care earlier than in the past. Thus, the decline in transition rate may be due to treatment being more effective at this very early stage of illness or it may be due to finding more false positives who were never at risk of psychosis, ie, a "dilution" effect. Given that it is not possible to distinguish between these alternatives at least phenotypically at present, perhaps it is time to rethink the role and practice of UHR clinics. Patients presenting to them need help. It may be that we need to aim to prevent a range of target syndromes.

The vulnerability to alcohol and substance abuse in individuals diagnosed with schizophrenia

Individuals with schizophrenia are at increased risk for developing substance abuse disorders. Here, we consider factors that might elevate their risk for substance abuse. The tendency among schizophrenic individuals to overvalue drug-like rewards and to devalue the potential negative consequences of substance abuse may be a contributing factor to their substance abuse risk. This bias, which may partly reflect the convergence of glutamatergic and dopaminergic input to the limbic striatum, also may contribute to disadvantageous decision-making and other impulsive behavior. This propensity to seek drug-like rewards is augmented by alterations in nicotinic cholinergic, GABAergic, glutamatergic, and cannabinnoid receptor function associated with schizophrenia that increase the abuse liability of low doses of nicotine, ethanol, and perhaps cannabis, and augment the dysphoric effects of higher doses of ethanol and cannabis. The distortions in reward processing and altered response to substances of abuse also increase the likelihood that individuals with schizophrenia will self-medicate their subjective distress with abused substances. The focus on distinctions between motivation and reward with respect to substance abuse risk by schizophrenic patients suggests a need for a reconsideration of the construct of "negative symptoms" for this dually-diagnosed patient group.

Associations between volume of alcohol consumption and social status, intelligence, and personality in a sample of young adult Danes

Relatively few studies have investigated associations between volume of alcohol consumption and psychological characteristics in normal samples. A sub-sample, comprising 363 men and 331 women between 29 and 34 years of age, was selected from the Copenhagen Perinatal Cohort on the basis of perinatal records. The sample was divided into four consumption categories: abstainers (including occasional drinkers), light, moderate, and risk drinkers. ANOVA and relevant contrasts were used to test the significance of differences among consumption categories. Both abstaining and risk drinking were associated with low social status family background, low education and intelligence. Abstaining was associated with low disinhibition and social recognition scores, while risk drinking was associated with high neuroticism and, in males, high disinhibition, low social recognition, and low achievement scores. Compared with light drinkers, a more "carefree" life orientation characterized male moderate drinkers, while relatively high scores on anxiety, dysthymia, and somatoform symptom scales characterized female moderate drinkers.

Outpatient drug abuse treatment for Hispanic adolescents

The objective of this article is to review the state of the science in evidence-based drug abuse treatments for Hispanic adolescents, highlight scientific opportunities, and offer recommendations to further the field of drug abuse treatment for this population. The article is divided into seven sections: boundaries for this review, drug abuse and associated problems, behavioral treatment, cultural issues in hispanic adolescent behavioral drug abuse treatment, pharmacological treatment, gender differences in treatment, and scientific opportunities/recommendations. Although only one treatment approach, Brief Strategic Family Therapy, has been empirically shown to be efficacious in treating Hispanic adolescent drug abusers, with some modifications other treatments may also have the potential to be efficacious with Hispanic adolescents. Family-based approaches, which typically appear to be most efficacious with adolescents in general, may also have the greatest potential to treat drug abuse in Hispanic adolescents.

Linking Substance Use and Problem Behavior Across Three Generations

This study examined patterns of between-generation continuity in substance use from generation 1 (G1) parents to generation 2 (G2) adolescents and from G2 adult substance use and G1 substance use to generation 3 (G3) problem behavior in childhood. Structural equation modeling of prospective, longitudinal data from 808 participants, their parents, and their children showed low levels of G1 to G2 cross-generational continuity in the general tendency to use drugs. This effect was fully mediated by G2 early adolescent behavior problems. Drug-specific residual effects were observed across generations for cigarette smoking. Once established in adolescence, substance use in G2 showed stability over time. G2 substance use at age 27 significantly predicted G3 problem behavior. G1 substance use also was related to G3 problem behavior indirectly. These findings highlight the importance of interrupting intergenerational cycles of substance use and problem behavior.

Behavioral predictors of substance-use initiation in adolescents with and without attention-deficit/hyperactivity disorder

OBJECTIVE

Our goal was to examine substance-use initiation in healthy adolescents and in adolescents who have been diagnosed with attention-deficit/hyperactivity disorder.

METHODS

Seventy-eight adolescents (28 healthy and 50 with attention-deficit/hyperactivity disorder) participated in an ongoing longitudinal study of predictors of substance use. The substances most commonly reported were tobacco, alcohol, and marijuana. Aggression, conduct problems, hyperactivity, impulsivity, inattention, anxiety/depression, social difficulties, and somatic complaints were assessed at study entry and tested as predictors for later substance use.

RESULTS

With an average of 4 years into the study, 37 adolescents had not used any substances, 41 had experimented with at least 1 substance, and 29 experimented with >1 substance. Psychiatric diagnoses (attention-deficit/hyperactivity disorder, attention-deficit/hyperactivity disorder and conduct disorder, and attention-deficit/hyperactivity disorder and depression/anxiety) did not influence reports of substance use. Distinct behavioral measures collected at study entry predicted use of different substances. In a multivariate analysis, aggression had the greatest association with tobacco smoking and marijuana use. Impulsivity was associated with alcohol use. Severity of drug exposure, indexed by the number of substances used, was predicted by aggression.

CONCLUSIONS

This 4-year longitudinal study captured the onset of substance use, not abuse. Behavioral predictors differed with the type of substance used. These behavioral characteristics may raise suspicion among pediatricians for enhanced risk for substance-use initiation.

Applying Transdisciplinary Research Strategies to Understanding and Eliminating Health Disparities

This overview for the special issue of Health Education & Behavior on “Health Disparities and Social Inequities” briefly outlines the transdisciplinary (TD) approach to research and examines the scope of TD science. The need to embrace basic science as well as several domains of applied research is discussed along the TD “pipeline” from discovery to development to delivery to policy. The overview concludes with selected examples of the emerging TD science of disparities. One central challenge for a TD approach is the need to strengthen what is being called “the science of dissemination” along with improving the “dissemination of evidence-based science.”

Challenges in genetic studies of the etiology of substance use and substance use disorders: introduction to the special issue

Misuse of psychoactive substances is associated with substantial costs to users and to society. A growing literature suggests individual differences in vulnerability to develop substance related problems are influenced to a large degree by genetic factors. We review the evidence from genetic epidemiologic and molecular genetic studies of problematic use of alcohol, tobacco, and other drugs, then discuss the challenges for the next generation of studies of genetic influences on substance use. These challenges are addressed in the remaining papers of this special issue. The papers cover a variety of approaches, substances, and non-human as well as human studies, but are united by their focus on going beyond heritability estimates to address the mechanisms and processes underlying the development of substance use and substance related problems, including measurement, precursors of substance abuse, stages of substance involvement, and specificity of genetic influences.

Gender-related pathways for behavior problems in the offspring of alcoholic fathers

The objective of the present study was to examine gender differences in the influence of paternal alcoholism on children's social-emotional development and to determine whether paternal alcoholism is associated with a greater number of externalizing symptoms in the male offspring. From the Mannheim Study of Risk Children, an ongoing longitudinal study of a high-risk population, the developmental data of 219 children [193 (95 boys and 98 girls) of non-alcoholic fathers, non-COAs, and 26 (14 boys, 12 girls) of alcoholic fathers, COAs] were analyzed from birth to the age of 11 years. Paternal alcoholism was defined according to the ICD-10 categories of alcohol dependence and harmful use. Socio-demographic data, cognitive development, number and severity of behavior problems, and gender-related differences in the rates of externalizing and internalizing symptoms were assessed using standardized instruments (IQ tests, Child Behavior Checklist questionnaire and diagnostic interviews). The general linear model analysis revealed a significant overall effect of paternal alcoholism on the number of child psychiatric problems (F = 21.872, d.f. = 1.217, P < 0.001). Beginning at age 2, significantly higher numbers of externalizing symptoms were observed among COAs. In female COAs, a pattern similar to that of the male COAs emerged, with the predominance of delinquent and aggressive behavior. Unlike male COAs, females showed an increase of internalizing symptoms up to age 11 years. Of these, somatic complaints revealed the strongest discriminating effect in 11-year-old females. Children of alcoholic fathers are at high risk for psychopathology. Gender-related differences seem to exist and may contribute to different phenotypes during development from early childhood to adolescence.

Revisiting drug progression: long-range effects of early tobacco use

AIMS

Drug progression models have been a cornerstone of scientific and public policy discussions for decades. These models have been criticized for their lack of causal mechanisms leading to drug dependence. Future research should focus on identification of pathways and covariates. This study re-examines tobacco use onset and progression to drug dependence in a multi-ethnic sample followed longitudinally from early to late adolescence (1990 to 1998-2000).

METHODS

Data were collected in schools (n = 1208) during early adolescence (mean age 11.07), and subsequently face-to-face interviews were conducted at late adolescence (mean age 20.01).

FINDINGS

Results indicated ethnic differences in rates and progression of tobacco use, with African Americans and foreign-born Latinos having larger proportions of abstainers and lower rates of persistent use. Most early adolescent smokers progressed to regular use. The odds of progression to marijuana abuse or dependence by later adolescence were highest (O.R. = 4.9) among persistent smokers, but not significant for foreign-born Latinos. The odds of progression to drug abuse or dependence were also highest (O.R. = 6.4) for persistent smokers, but not significant for African Americans.

CONCLUSIONS

Implications for research on pathways and mechanisms of progression are discussed. Prevention programs may interrupt drug progression if they delay onset of tobacco use until mid-adolescence. Preventing targeted marketing efforts by the tobacco industry, regulating and enforcing tobacco control laws and pricing cigarettes at cost levels that adolescents find prohibitive are effective supplements to traditional behavior change interventions.

The genetics of addictions: uncovering the genes

The addictions are common chronic psychiatric diseases that today are prevented and treated using relatively untargeted and only partially effective methods. The addictions are moderately to highly heritable, which is paradoxical because these disorders require use; a choice that is itself modulated by both genes and environment. The addictions are interrelated and related to other psychiatric diseases by common neurobiological pathways, including those that modulate reward, behavioural control and the anxiety or stress response. Our future understanding of addictions will be enhanced by the identification of genes that have a role in altered substance-specific vulnerabilities such as variation in drug metabolism or drug receptors and a role in shared vulnerabilities such as variation in reward or stress resiliency.

Genetic determinants of addiction to opioids and cocaine

OBJECTIVE

The completion of the human genome sequence has spurred investigation of the genetic contribution to substance dependence. In this article some of the recent scientific evidence for genetic determinants of opioid and cocaine dependence is reviewed.

METHOD

An electronic search of the medical literature was conducted to locate published studies relevant to the genetics of opioid and cocaine dependence. The collected information judged to be most pertinent is described and discussed.

RESULTS

Genetic epidemiologic studies support a high degree of heritable vulnerability for both opioid and cocaine dependence. Polymorphisms in the genes coding for dopamine receptors and transporter, opioid receptors, endogenous opioid peptides, cannabinoid receptors, and serotonin receptors and transporter all appear to be associated with the phenotypic expression of this vulnerability once opioids or cocaine are consumed.

CONCLUSIONS

Despite this initial progress, identification of specific genes and quantification of associated risk for the expression of each gene remain to be elucidated. While alteration of an individual's genome to change the phenotype seems remote, future interventions for treatment of opioid and cocaine dependence may include precise medications targeted to block the effects of proteins that have been identified through genetic research.