Behavioral disinhibition and the development of substance-use disorders: findings from the Minnesota Twin Family Study

Aversive startle potentiation and fear pathology: Mediating role of threat sensitivity and moderating impact of depression

Enhanced startle reactivity during exposure to unpleasant cues (aversive startle potentiation; ASP) appears in the RDoC matrix as a physiological index of acute threat response. Increased ASP has been linked to focal fear disorders and to scale measures of dispositional fearfulness (i.e., threat sensitivity; THT+). However, some studies have reported reduced ASP for fear pathology accompanied by major depressive disorder (MDD) or pervasive distress. The current study evaluated whether (a) THT+ as indexed by reported dispositional fearfulness mediates the relationship between fear disorders (when unaccompanied by depression) and ASP, and (b) depression moderates relations of THT+ and fear disorders with ASP. Fear disorder participants without MDD showed enhanced ASP whereas those with MDD (or other distress conditions) showed evidence of reduced ASP. Continuous THT+ scores also predicted ASP, and this association: (a) was likewise moderated by depression/distress, and (b) accounted for the relationship between ASP and fear pathology without MDD. These findings point to a role for the RDoC construct of acute threat, operationalized dispositionally, in enhanced ASP shown by individuals with fear pathology unaccompanied by distress pathology.

Cortisol reactivity to social stress as a mediator of early adversity on risk and adaptive outcomes

Children chronically exposed to stress early in life are at increased risk for maladaptive outcomes, though the physiological mechanisms driving these effects are unknown. Cortisol reactivity was tested as a mediator of the relation between prenatal substance exposure and/or early adversity on adaptive and maladaptive outcomes. Data were drawn from a prospective longitudinal study of prenatal substance exposure (N = 860). Cortisol reactivity was assessed at age 11. Among African Americans, prenatal substance exposure exerted an indirect effect through early adversity and cortisol reactivity to predict externalizing behavior, delinquency, and a positive student-teacher relationship at age 11. Decreased cortisol reactivity was related to maladaptive outcomes, and increased cortisol reactivity predicted better executive functioning and a more positive student-teacher relationship.

Developmental trajectories of disordered eating from early adolescence to young adulthood: a longitudinal study

OBJECTIVE

Research examining changes in eating disorder symptoms across adolescence suggests an increase in disordered eating from early to late adolescence. However, relevant studies have largely been cross-sectional in nature and most have not examined the changes in the attitudinal symptoms of eating disorders (e.g., weight concerns). This longitudinal study aimed to address gaps in the available data by examining the developmental trajectories of disordered eating in females from preadolescence into young adulthood.

METHOD

Participants were 745 same-sex female twins from the Minnesota Twin Family Study. Disordered eating was assessed using the Total Score, Body Dissatisfaction subscale, Weight Preoccupation subscale, and a combined Binge Eating and Compensatory Behavior subscale from the Minnesota Eating Behavior Survey assessed at the ages of 11, 14, 18, 21, and 25. Several latent growth models were fit to the data to identify the trajectory that most accurately captures the changes in disordered eating symptoms from 11 to 25 years.

RESULTS

The best-fitting models for overall levels of disordered eating, body dissatisfaction, and weight preoccupation showed an increase in from 11 through 25 years. In contrast, bulimic behaviors increased to age of 18 and then stabilized to age of 25.

DISCUSSION

The findings expanded upon extant research by investigating longitudinal, symptom specific, within-person changes and showing an increase in cognitive symptoms into young adulthood and the stability of disordered eating behaviors past late adolescence.

The contributions of early adverse experiences and trajectories of respiratory sinus arrhythmia on the development of neurobehavioral disinhibition among children with prenatal substance exposure

Neurobehavioral disinhibition (ND) is a complex condition reflecting a wide range of problems involving difficulties with emotion regulation and behavior control. Respiratory sinus arrhythmia (RSA) is a physiological correlate of emotion regulation that has been studied in a variety of at-risk populations; however, there are no studies of RSA in children with ND. Data were drawn from a prospective longitudinal study of prenatal substance exposure that included 1,073 participants. Baseline RSA and RSA reactivity to an attention-demanding task were assessed at 3, 4, 5, and 6 years. ND was assessed at ages 8/9, 11, and 13/14 years via behavioral dysregulation and executive dysfunction composite measures. Greater exposure to early adversity was related to less RSA reactivity at 3 years, increases in RSA reactivity from ages 3 to 6 years, and increased behavioral dysregulation from ages 8/9 to 13/14. RSA reactivity was examined as a moderator of the association between early adversity and changes in ND. A significant Early Adversity × RSA Reactivity quadratic interaction revealed that children with decelerations in RSA reactivity exhibited increases in behavioral dysregulation, regardless of their exposure to early adversity. However, greater exposure to early adversity was related to greater increases in behavioral dysregulation, but only if children exhibited accelerations in RSA reactivity from ages 3 to 6 years. The results contribute to our understanding of how interactions across multiple levels of analysis contribute to the development of ND.

Parental involvement moderates etiological influences on attention deficit hyperactivity disorder behaviors in child twins

Although few would now contest the presence of Gene × Environment (G × E) effects in the development of child psychopathology, it remains unclear how these effects manifest themselves. Alternative G × E models have been proposed (i.e., diathesis-stress, differential susceptibility, bioecological), each of which has notably different implications for etiology. Child twin studies present a powerful tool for discriminating between these models. The current study examined whether and how parental involvement moderated etiological influences on attention deficit hyperactivity disorder (ADHD) within 500 twin pairs aged 6-11 years. Results indicated moderation of genetic and nonshared environmental contributions to ADHD by parental involvement, and moreover, suggested both differential susceptibility and bioecological models of G × E. Results highlight the utility of child twin samples in testing different manifestations of G × E effects.

The developmental progression of age 14 behavioral disinhibition, early age of sexual initiation, and subsequent sexual risk-taking behavior

BACKGROUND

Research has demonstrated a consistent relationship between early sexual experience and subsequent sexual risk-taking behaviors. We hypothesized that this relationship is due to a general predisposition toward behavioral disinhibition (BD), and that relationships among BD, early sex, and subsequent risky sexual behavior may be influenced by common genetic influences for males and common environmental influences for females.

METHODS

A prospective sample of 1,512 same-sex adolescent twins (50.2% female) was used. Adolescent BD was measured by clinical symptom counts of conduct disorder, oppositional defiant disorder, and self-reported delinquent behavior (age 14). Age of sexual initiation was defined as first age of consensual oral or penetrative sex (mean age ~17). Adult risky sexual behavior was defined by sexual behaviors under the influence of drugs and alcohol and number of casual sexual partners in the past year (age 24).

RESULTS

Multivariate analyses showed evidence for substantial common genetic variance among age 14 BD, age at sexual initiation, and adult risky sexual behavior for males, but not females. There was no significant difference in the degree of common environmental influence on these variables for females compared to males. Notably, age of sexual initiation was not significantly correlated with age 24 risky sexual behavior for females.

CONCLUSION

The relationship between early sex and later risky sex can be better understood through a general liability toward BD, which is influenced primarily by genetic factors for males. The association between age 14 BD and age of sexual initiation was influenced through a combination of genetic and environmental factors for females; however, age of sexual initiation does not appear to be a salient predictor of adult women’s sexual risk-taking behavior. Findings suggest that prevention programs aimed at reducing sexual risk behavior might target youth exhibiting BD by age 14, particularly males. More research is needed on what predicts adult sexual risk-taking behavior for females.

Adolescent drinking and motivated decision-making: a cotwin-control investigation with monozygotic twins

The present study used a monozygotic (MZ) cotwin-control (CTC) design to investigate associations between alcohol use and performance on the Iowa gambling task (IGT) in a sample of 96 adolescents (half female). The MZ CTC design is well suited to shed light on whether poor decision-making, as reflected on IGT performance, predisposes individuals to abuse substances or is a consequence of use. Participants completed structural MRI scans as well, from which we derived gray matter volumes for cortical and subcortical regions involved in IGT performance and reduced in adolescents with problematic alcohol use. Drinking was associated with poorer task performance and with reduced volume of the left lateral orbital-frontal cortex. CTC analyses indicated that the former was due to differences between members of twin pairs in alcohol use (suggesting a causal effect of alcohol), whereas the latter was due to factors shared by twins (consistent with a pre-existing vulnerability for use). Although these preliminary findings warrant replication, they suggest that normative levels of alcohol use may diminish the quality of adolescent decision-making and thus have potentially important public health implications.

Personality and Psychopathology: A Stagnant Field in Need of Development

A dominant paradigm in psychopathology research proposes that individual differences in personality are centrally involved in the origins and manifestations of psychopathology, and structural models of personality and psychopathology have been extremely useful in helping to organize associations among many traits and disorders. However, these models merely describe patterns of covariation; they do not explain the processes by which these patterns emerge. We argue that the field is stagnated, as it is overly focused on the demonstration of concurrent associations and on confirming a spectrum model that proposes traits and disorders are manifestations of the same underlying constructs. We contend that if the field is to move toward an understanding of causal processes, it must integrate knowledge and principles of personality development and developmental psychopathology. To begin this integration, we review (1) normative trends in personality change, (2) age-related changes in the prevalence of disorders, and (3) the impact of onset and chronicity on the severity of disorders. We propose several developmental processes that may contribute to the co-development of personality and psychopathology. We then present novel empirical findings to illustrate how a developmental perspective on traits and disorders can inform new hypotheses, and propose principles and hypotheses that should guide future research.

Alcohol use disorder in women: Risks and consequences of an adolescent onset and persistent course

Women are more vulnerable to the deleterious effects of both acute and protracted alcohol use than men, but women's lower levels of alcohol consumption and alcohol use disorder (AUD) have resulted in a paucity of investigations on the development of alcohol problems in women. In particular, it is not clear to what extent the cascading effects of key etiological factors that contribute to an especially severe course of AUD in men also underlie the development of AUD in women. To fill this gap, we examined the adolescent risk factors and adult consequences associated with an adolescent onset and persistent course of AUD in a community sample of women (n = 636) from ages 17 to 29. Women with AUD exhibited greater psychopathology and psychosocial impairment than those without, with an adolescent onset and persistent course indicative of the greatest severity. Notably, high levels of impairment across all women with AUD reduced the utility of onset and course to differentiate profiles of risk and impairment. In contrast to previous work in men, even women whose AUD symptoms desisted continued to exhibit impairment, suggesting that an adolescent onset of AUD is associated with enduring consequences for women's health and functioning, even after ostensible "recovery."

Estimation of skin conductance at low frequencies using measurements at higher frequencies for EDA applications

Using low-frequency (LF) alternating current skin conductance (SC) has recently been recommended for electrodermal activity (EDA) measurement, but the method may imply some limitations in sampling rate, which are insufficient for capturing the complete SC waveform. The aim of this study was to assess whether LF SC can be estimated based on skin admittance (SA) measurements at higher frequencies allowing higher sampling rates. SA measurements from 1 Hz to 70 kHz were gathered from 20 healthy human participants, and an interval from 500 Hz to 10 kHz was used to fit a Cole model to the measured SA by means of the nonlinear least squares method. The LF extrapolation of this fit was used to estimate the LF SC at 1, 10, 22 and 30 Hz. The method produced an overestimation of SC by approximately 20%, and the variation in LF SC was preserved by approximately 95%. The overestimation is most likely due to different frequency dependence behavior (dispersion) of SC at the lowest frequencies, which is not accounted for by a single dispersion model. In conclusion, the SA method using high frequency is unsuitable for estimation of the LF SC level, but can probably be used in EDA measurements, which are scored based on the variations in SC.

Risky cannabis use is associated with alexithymia, frontal lobe dysfunction, and impulsivity in young adult cannabis users

Risky or problematic alcohol use by young adults has been found to be associated with factors such as alexithymia, frontal lobe dysfunction, reward sensitivity, and impulsivity. One interpretation is that these factors reflect inherent traits that predispose to risky substance use in general, a notion examined in the present study. Alexithymia, everyday frontal lobe functioning, sensitivity to reward and punishment, and impulsivity were examined in 138 young adult cannabis users who were divided into Low Risk (n = 99) and Risky (n = 39) users according to their Cannabis Use Disorder Identification Test (CUDIT) scores. Risky cannabis use was significantly positively associated with alexithymia, multiple signs of frontal lobe dysfunction in everyday life, and impulsivity. A broader pattern of dysfunction was indicated for risky cannabis use than for risky alcohol use in this sample. Findings are interpreted as likely reflecting not only inherent traits that predispose to risky substance use in general, but also perhaps residual effects of recent heavy cannabis use in the Risky user group. Longitudinal research is needed to disentangle these competing possibilities.

The role of early childhood ADHD and subsequent CD in the initiation and escalation of adolescent cigarette, alcohol, and marijuana use

Adolescents with attention deficit/hyperactivity disorder (ADHD) are at an increased risk for substance use but the pathways through which this risk emerges are insufficiently understood. Tobacco, alcohol, and marijuana outcomes were compared between adolescents diagnosed with ADHD in early childhood (N = 113) and demographically similar controls (N = 65). Participants were assessed from age 5 until age 18. A comprehensive history of adolescent substance use was compiled for each participant and growth in ADHD and conduct disorder (CD) were modeled as they related to substance use outcomes. Results indicated that when compared with controls, adolescents with ADHD were more likely to try cigarettes, initiate alcohol use at early ages, and smoke marijuana more frequently. Furthermore, adolescents with ADHD were 4 to 5 times more likely than controls to escalate to heavy cigarette and marijuana use after trying these substances once. Adolescents with ADHD who escalated to heavy use patterns were more likely to display early cigarette use and marked problems with family members, but displayed fewer peer problems. There was evidence of baseline effects (latent intercept, measured at age 5) for both ADHD and CD on substance use outcomes. Furthermore, growth in ADHD symptoms accounted for much of the growth in CD symptoms, and consequently, escalating CD symptoms in childhood (latent slope) were viewed as a mediator of the relationship between ADHD and cigarette and marijuana use. Maternal drinking in early childhood was the strongest predictor of early adolescent alcohol use. These findings are discussed with respect to the role of ADHD in the development of adolescent risk outcomes.

General and substance-specific predictors of young adult nicotine dependence, alcohol use disorder, and problem behavior: replication in two samples

BACKGROUND

This paper presents two replications of a heuristic model for measuring environment in studies of gene-environment interplay in the etiology of young adult problem behaviors.

METHODS

Data were drawn from two longitudinal, U.S. studies of the etiology of substance use and related behaviors: the Raising Healthy Children study (RHC; N=1040, 47% female) and the Minnesota Twin Family Study (MTFS; N=1512, 50% female). RHC included a Pacific Northwest, school-based, community sample. MTFS included twins identified from state birth records in Minnesota. Both studies included commensurate measures of general family environment and family substance-specific environments in adolescence (RHC ages 10-18; MTFS age 18), as well as young adult nicotine dependence, alcohol and illicit drug use disorders, HIV sexual risk behavior, and antisocial behavior (RHC ages 24, 25; MTFS age 25).

RESULTS

Results from the two samples were highly consistent and largely supported the heuristic model proposed by Bailey et al. (2011). Adolescent general family environment, family smoking environment, and family drinking environment predicted shared variance in problem behaviors in young adulthood. Family smoking environment predicted unique variance in young adult nicotine dependence. Family drinking environment did not appear to predict unique variance in young adult alcohol use disorder.

CONCLUSIONS

Organizing environmental predictors and outcomes into general and substance-specific measures provides a useful way forward in modeling complex environments and phenotypes. Results suggest that programs aimed at preventing young adult problem behaviors should target general family environment and family smoking and drinking environments in adolescence.

The Behavioural Genetics of Personality Development in Adulthood—Classic, Contemporary, and Future Trends

Behavioural genetic research has led to important advances in the field of personality psychology. When carried out on longitudinal data, behavioural genetic studies also offer promising ways to examine the genetic and environmental origins of personality stability and change. Here, we review the findings of longitudinal twin studies, discuss their implications for our understanding of adult personality development, and point out open questions that need to be addressed by future research. Three general conclusions stand out. First, there is a strong and relatively stable genetic foundation of individual differences in personality throughout the adult life span; second, environmental influences become more important and contribute to an increasing rank–order stability of personality traits from early to middle adulthood; and third, both genetic and nonshared environmental influences contribute to both stability and change in personality traits. Equipped with this knowledge, the most urgent tasks for the next generation of behavioural genetic studies on personality development will be to (i) identify measurable environmental factors that matter and (ii) to capture the interplay between genetic and environmental influences on personality stability and change throughout adulthood. Copyright © 2014 European Association of Personality Psychology

Understanding the role of conscientiousness in healthy aging: where does the brain come in?

In reviewing this impressive series of articles, I was struck by 2 points in particular: (a) the fact that the empirically oriented articles focused on analyses of data from very large samples, with the articles by Friedman, Kern, Hampson, and Duckworth (2014) and Kern, Hampson, Goldbert, and Friedman (2014) highlighting an approach to merging existing data sets through use of "metric bridges" to address key questions not addressable through 1 data set alone, and (b) the fact that the articles as a whole included limited mention of neuroscientific (i.e., brain research) concepts, methods, and findings. One likely reason for the lack of reference to brain-oriented work is the persisting gap between smaller sample size lab-experimental and larger sample size multivariate-correlational approaches to psychological research. As a strategy for addressing this gap and bringing a distinct neuroscientific component to the National Institute on Aging's conscientiousness and health initiative, I suggest that the metric bridging approach highlighted by Friedman and colleagues could be used to connect existing large-scale data sets containing both neurophysiological variables and measures of individual difference constructs to other data sets containing richer arrays of nonphysiological variables-including data from longitudinal or twin studies focusing on personality and health-related outcomes (e.g., Terman Life Cycle study and Hawaii longitudinal studies, as described in the article by Kern et al., 2014).

A construct-network approach to bridging diagnostic and physiological domains: application to assessment of externalizing psychopathology

A crucial challenge in efforts to link psychological disorders to neural systems, with the aim of developing biologically informed conceptions of such disorders, is the problem of method variance (Campbell & Fiske, 1959). Since even measures of the same construct in differing domains correlate only moderately, it is unsurprising that large sample studies of diagnostic biomarkers yield only modest associations. To address this challenge, a construct-network approach is proposed in which psychometric operationalizations of key neurobehavioral constructs serve as anchors for identifying neural indicators of psychopathology-relevant dispositions, and as vehicles for bridging between domains of clinical problems and neurophysiology. An empirical illustration is provided for the construct of inhibition-disinhibition, which is of central relevance to problems entailing deficient impulse control. Findings demonstrate that: (1) a well-designed psychometric index of trait disinhibition effectively predicts externalizing problems of multiple types, (2) this psychometric measure of disinhibition shows reliable brain response correlates, and (3) psychometric and brain-response indicators can be combined to form a joint psychoneurometric factor that predicts effectively across clinical and physiological domains. As a methodology for bridging between clinical problems and neural systems, the construct-network approach provides a concrete means by which existing conceptions of psychological disorders can accommodate and be reshaped by neurobiological insights.

Impulsivity, risk taking, and cortisol reactivity as a function of psychosocial stress and personality in adolescents

Although adolescence is characterized by hormonal changes and increased disinhibited behaviors, explanations for these developmental changes that include personality and environmental factors have not been fully elucidated. We examined the interactions between psychosocial stress and the traits of negative emotionality and constraint on impulsive and risk-taking behaviors as well as salivary cortisol reactivity in 88 adolescents. In terms of behavioral outcomes, analyses revealed that negative emotionality and constraint were protective of impulsivity and risk taking, respectively, for adolescents in the no-stress condition; personality did not relate to either behavior in the stress condition. Low-constraint adolescents in the stress condition engaged in less risk taking than low-constraint adolescents in the no-stress condition, whereas there was no effect of stress group for high-constraint adolescents. In terms of cortisol reactivity, analyses revealed that low-constraint adolescents in the stress condition exhibited greater cortisol reactivity compared to high-constraint adolescents, which suggests that low-constraint adolescents mobilize greater resources (e.g., increased cognitive control, heightened attention to threat) in stressful situations relative to nonstressful ones. These results demonstrate that two facets of disinhibition and cortisol reactivity are differentially affected by psychosocial stress and personality (and their interactions) in adolescents.

Does electroencephalogram phase variability account for reduced P3 brain potential in externalizing disorders?

OBJECTIVE

Amplitude deficits of the P3 event-related potential (ERP) are associated with externalizing psychopathology but little is known about the nature of underlying brain electrical activity that accounts for this amplitude reduction. We sought to understand if group differences in task-induced phase-locking in electroencephalographic (EEG) delta and theta frequencies may account for P3-externalizing associations.

METHODS

Adult males (N=410) completed a visual oddball task and frontal and parietal P3-related delta- and theta-band phase-invariant evoked energy and inter-trial phase-locking measures were investigated with respect to the externalizing spectrum, including substance dependence, adult antisociality, and childhood disruptive disorders. We hypothesized that P3-related phase-locking is weaker in externalizing-diagnosed individuals and this might mediate prior findings of reduced evoked P3 energy.

RESULTS

Reductions in both evoked energy and phase-locking, in both frequency bands, at both scalp sites, were associated with greater odds of externalizing diagnoses. Generally, adding phase-locking to evoked energy came with better prediction model fit. Moreover, reduced theta-band phase-locking partially mediated the effects of within-frequency evoked energy on externalizing prediction.

CONCLUSIONS

Inter-trial phase-locking underlying P3 appears to be an important distinction between externalizing and control subjects.

SIGNIFICANCE

This cross-trial phase-variability for externalizing-diagnosed individuals might reflect deficient top-down "tuning" by neuromodulatory systems.

The effect of paternal age on offspring intelligence and personality when controlling for paternal trait level

Paternal age at conception has been found to predict the number of new genetic mutations. We examined the effect of father’s age at birth on offspring intelligence, head circumference and personality traits. Using the Minnesota Twin Family Study sample we tested paternal age effects while controlling for parents’ trait levels measured with the same precision as offspring’s. From evolutionary genetic considerations we predicted a negative effect of paternal age on offspring intelligence, but not on other traits. Controlling for parental intelligence (IQ) had the effect of turning an initially positive association non-significantly negative. We found paternal age effects on offspring IQ and Multidimensional Personality Questionnaire Absorption, but they were not robustly significant, nor replicable with additional covariates. No other noteworthy effects were found. Parents’ intelligence and personality correlated with their ages at twin birth, which may have obscured a small negative effect of advanced paternal age (<1% of variance explained) on intelligence. We discuss future avenues for studies of paternal age effects and suggest that stronger research designs are needed to rule out confounding factors involving birth order and the Flynn effect.

Genetic and environmental factors underlying comorbid bulimic behaviours and alcohol use disorders: a moderating role for the dysregulated personality cluster?

Women with bulimia nervosa (BN) frequently have co-occurring alcohol use disorders (AUDs). Studies of shared genetic transmission of these disorders have been mixed. Personality heterogeneity among individuals with BN may explain discrepant findings. Cluster analysis has characterized women with BN in groups on the basis of personality profiles. One group, the Dysregulated cluster, characterized largely by behavioural disinhibition and emotional dysregulation may be more closely linked etiologically to AUDs. This study examined whether genetic associations between BN and AUDs are the strongest among the Dysregulated cluster. Symptoms of BN and AUDs were assessed in female twins at ages 17 and 25 years from the Minnesota Twin Family Study. Personality clusters were defined using the Multidimensional Personality Questionnaire. Twin moderation models suggested small-to-moderate common genetic transmission between BN and AUDs. However, shared genetic effects did not differ by personality cluster. Findings suggest that personality clusters are unlikely to account for inconsistent findings regarding their shared aetiology.

Obesity and depression in adolescence and beyond: reciprocal risks

Objective

Obesity and Major Depressive Disorder (MDD) are associated, but evidence about how they relate over time is conflicting. The goal of this study was to examine prospective associations between depression and obesity from early adolescence through early adulthood.

Methods

Participants were drawn from a statewide, community-based, Minnesota sample. MDD and obesity with onsets by early adolescence (by age 14), late adolescence (between 14 and 20), and early adulthood (ages 20 to 24) were assessed via structured interview (depression) and study-measured height and weight.

Results

Cross-sectional results indicated that depression and obesity with onsets by early adolescence were concurrently associated, but the same was not true later in development. Prospective results indicated that depression by early adolescence predicted the onset of obesity (odds ratio=3.76, confidence interval= 1.33–10.59) during late adolescence among females. Obesity that developed during late adolescence predicted the onset of depression (odds ratio=5.89, confidence interval= 2.31–15.01) during early adulthood among females.

Conclusions

For girls, adolescence is a high risk period for the development of this comorbidity, with the nature of the risk varying over the course of adolescence. Early adolescent-onset depression is associated with elevated risk of later onset obesity, and obesity, particularly in late adolescence, is associated with increased odds of later depression. Further investigation into the mechanisms of these effects and the reasons for the observed gender and developmental differences is needed. Prevention programs focused on early-onset cases of depression and adolescent-onset cases of obesity, particularly among females, may help in reducing risk for this form of comorbidity.

Gamma-aminobutyric acid system genes--no evidence for a role in alcohol use and abuse in a community-based sample

BACKGROUND

While twin and adoption studies point to substantial genetic influence upon alcohol use, dependence, and other alcohol-related phenotypes, few of the genes underlying variation in these phenotypes have been identified. Markers in genes related to GABAergic activity-a system integral to many of alcohol's biological effects-have been implicated in alcohol use and alcohol-related psychopathology in linkage and association studies.

METHODS

Using multiple methods, we conducted a comprehensive examination of the effects of markers in γ-aminobutyric acid (GABA) system genes in a community-based sample of 7,224 individuals assessed in early and middle adulthood. In addition to testing the effect of individual single nucleotide polymorphism (SNP) markers on alcohol-related phenotypes, we computed a polygenic score reflecting the aggregated effects of multiple GABA system SNPs. We also estimated the variance in alcohol-related phenotypes attributable to all GABA system markers considered simultaneously and conducted gene-based association tests.

RESULTS

No method produced results indicative of an effect of GABA system variants on measures of alcohol use or misuse.

CONCLUSIONS

These results reflect alcohol-related behaviors in a population-representative sample, many of whom are still in adolescence, and in which the incidence of heavy drinking and alcohol-related symptomatology are relatively low. Contrasted with existing studies of the association between alcohol use and GABA system genes, our results suggest that the relationship may be limited to particular contexts, such as when accompanied by polysubstance abuse or a familial history of alcoholism.

Low-Frequency Copy-Number Variants and General Cognitive Ability: No Evidence of Association

Although twin, family, and adoption studies have shown that general cognitive ability (GCA) is substantially heritable, GWAS has not uncovered a genetic polymorphism replicably associated with this phenotype. However, most polymorphisms used in GWAS are common SNPs. The present study explores use of a different class of genetic variant, the copy-number variant (CNV), to predict GCA in a sample of 6,199 participants, combined from two longitudinal family studies. We aggregated low-frequency (<5%) CNV calls into eight different mutational burden scores, each reflecting a different operationalization of mutational burden. We further conducted three genome-wide association scans, each of which utilized a different subset of identified low-frequency CNVs. Association signals from the burden analyses were generally small in effect size, and none were statistically significant after a careful Type I error correction was applied. No signal from the genome-wide scans significantly differed from zero at the adjusted Type I error rate. Thus, the present study provides no evidence that CNVs underlie heritable variance in GCA, though we cannot rule out the possibility of very rare or small-effect CNVs for this trait, which would require even larger samples to detect. We interpret these null results in light of recent breakthroughs that aggregate SNP effects to explain much, but not all, of the heritable variance in some quantitative traits.

The adolescent origins of substance use disorders: a behavioral genetic perspective

Over the past twenty years there has been an increasing recognition within the substance abuse research field that substance use disorders (SUDs) are usefully conceptualized within a developmental framework. That is, initiation of substance use in adolescence and escalation to substance abuse in early adulthood are strongly age-graded, with the relevant behavioral risk and protective factors manifesting early in development, often prior to substance use onset. In this chapter we review a program of research that seeks to provide a behavioral genetic perspective on the development of SUDs. The Minnesota Center for Twin and Family Research (MCTFR) undertakes longitudinal research on families including twins, adopted siblings and non-adopted siblings spanning early adolescence through early adulthood. A total of nearly 10,000 individuals in 2500 families have participated in MCTFR research. We review findings from the MCTFR to establish four general features of the development of SUDs informed by behavioral genetic research: 1) Both general and specific processes contribute to the aggregation of SUDs in families; 2) genetic contributions to SUD risk appear to be primarily at the general factor level, although the contribution of the general factor appears to decrease with age; 3) SUD risk is manifested before initiation of substance use in terms of elevated levels of externalizing psychopathology and personality characteristics indicative of low self-control; and 4) the genetic factors that contribute to SUD risk appear to be numerous with very small phenotypic effects, making them difficult to identify.

Lifetime prevalence and co-morbidity of externalizing disorders and depression in prospective assessment

BACKGROUND

Epidemiological research is believed to underestimate the lifetime prevalence of mental illness due to recall failure and a lack of rapport between researchers and participants.

METHOD

In this prospective study, we examined lifetime prevalence and co-morbidity rates of substance use disorders, antisocial personality disorder (ASPD) and major depressive disorder (MDD) in a representative, statewide Minnesota sample (n = 1252) assessed four times between the ages of 17 and 29 years with very low attrition.

RESULTS

Lifetime prevalence rates of all disorders more than doubled between the ages of 17 and 29 years in both men and women, and our prospective rates at the age of 29 years were consistently higher than rates from leading epidemiological surveys. Although there was some variation, the general trend was for lifetime co-morbidity to increase between the ages of 17 and 29 years, and this trend was significant for MDD-alcohol dependence, MDD-nicotine dependence, and ASPD-nicotine dependence.

CONCLUSIONS

Overall, our results show that emerging adulthood is a high-risk period for the development of mental illness, with increases in the lifetime prevalence and co-morbidity of mental disorders during this time. More than a quarter of individuals had met criteria for MDD and over a fifth had experienced alcohol dependence by the age of 29 years, indicating that mental illness is more common than is estimated in cross-sectional mental health surveys. These findings have important implications for the measurement of economic burden, resource allocation toward mental health services and research, advocacy organizations for the mentally ill, and etiological theories of mental disorders.

A further validation of the Minnesota Borderline Personality Disorder Scale

Previous research indicates that borderline personality disorder (BPD) is well conceptualized as a dimensional construct that can be represented using normal personality traits. A previous study successfully developed and validated a BPD measure embedded within a normal trait measure, the Minnesota Borderline Personality Disorder Scale (MBPD). The current study performed a further validation of the MBPD by examining its convergent validity, external correlates, and heritability in a sample of 429 female twins. The MBPD correlated strongly with the Structured Clinical Interview for DSM-IV Axis II Personality Disorders (SCID-II) screener for BPD and moderately with external correlates. Moreover, the MBPD and SCID-II screener exhibited very similar patterns of external correlations. Additionally, results indicated that the genetic and environmental influences on MBPD overlap with the genetic and environmental influences on the SCID-II screener, which suggests that these scales are measuring the same construct. These data provide further evidence for the construct validity of the MBPD.

The role of constraint in the development of nicotine, marijuana, and alcohol dependence in young adulthood

The personality-related construct of behavioral disinhibition is hypothesized to confer a generalized risk for alcohol and drug dependence. On average, rates of substance use and scores on measures of disinhibition peak in adolescence and decline as people mature into adulthood. The present study investigated this developmental change by evaluating the relationship between disinhibition and substance use disorders using a longitudinal study of 2,608 twins assessed at ages 17, 24, and 29. These ages include the period of highest risk for substance use disorders (ages 17-24) as well as when substance dependence symptoms typically decline (ages 24-29). Disinhibition was measured with the Multidimensional Personality Questionnaire higher-order scale of Constraint, as well as its constituent facet scales of Harm Avoidance, Control, and Traditionalism. Constraint's relationship with substance dependence was statistically significant but small and largely genetic, with the genetic relationship declining from adolescence into adulthood. However, this result appeared to be almost entirely driven by Traditionalism, a propensity to hold traditional moral and social values, and not an obvious component of behavioral disinhibition. The results suggest that personality measures of Control and Harm Avoidance play only a small role in the development of substance dependence during late adolescence, and previous findings linking personality measures of disinhibition and substance use may be driven significantly by social and moral values than deficits in impulse control.

Identifying childhood characteristics that underlie premorbid risk for substance use disorders: socialization and boldness

We utilized a longitudinal twin study (N = 2,510) to identify the child characteristics present prior to initiation of substance use that best predicted later substance use disorders. Two independent traits accounted for the majority of premorbid risk: socialization (conformity to rules and conventional values) and boldness (sociability and social assurance, stress resilience, and thrill seeking). Low socialization was associated with disruptive behavior disorders, parental externalizing disorders, and environmental adversity and exhibited moderate genetic (0.45) and shared environmental influences (0.30). Boldness was highly heritable (0.71) and associated with less internalizing distress and environmental adversity. In combination, these traits exhibited robust associations with adolescent and young adult substance use disorders (R = .48 and .50, respectively) and incremental prediction over disruptive behavior disorders, parental externalizing disorders, and environmental adversity. The results were replicated in an independent sample. Socialization and boldness offer a novel conceptualization of underlying risk for substance use disorders that has the potential to improve prediction and theory with implications for basic research, prevention, and intervention.

Blunted feedback processing during risky decision making in adolescents with a parental history of substance use disorders

Risky decision making, a hallmark phenotype of substance use disorders (SUD), is thought to be associated with deficient feedback processing. Whether these aberrations are present prior to SUD onset or reflect merely a consequence of chronic substance use on the brain remains unclear. The present study investigated whether blunted feedback processing during risky decision making reflects a biological predisposition to SUD. We assessed event-related potentials elicited by positive and negative feedback during performance of a modified version of the Balloon Analogue Risk Task (BART) among high-risk adolescents with a parental history of SUD (HR; n = 61) and normal-risk controls (NR; n = 91). HR males made significantly more risky and faster decisions during the BART than did NR controls. Moreover, HR adolescents showed significantly reduced P300 amplitudes in response to both positive and negative feedback as compared to NR controls. These differences were not secondary to prolonged substance use exposure. Results are discussed in terms of feedback-specific processes. Reduced P300 amplitudes in the BART may reflect poor processing of feedback at the level of overall salience, which may keep people from effectively predicting the probability of future gains and losses. Though conclusions are tentative, blunted feedback processing during risky decision making may represent a promising endophenotypic vulnerability marker for SUD.

Nicotine deprivation influences P300 markers of cognitive control

Studies suggest that reduced cognitive control due to nicotine withdrawal may have a critical role in promoting tobacco use. The P3 family of event-related brain potential (ERP) components is thought to serve as markers of cognitive control processes. Unfortunately, existing research that examines the effects of nicotine deprivation on P3 amplitude has been marred by small sample sizes and other design limitations. The present study sought to determine the effects of nicotine deprivation on P3b and P3a amplitudes, which index task relevant target detection and orienting responses to novelty, respectively. A secondary aim was to examine self-reported trait cognitive control as a moderator of nicotine deprivation-induced reductions in P3b and P3a amplitudes. In all, 121 nicotine-dependent smokers attended two experimental sessions following 12-h smoking/nicotine deprivation. In a counterbalanced manner, participants smoked nicotine cigarettes during one session and placebo cigarettes during the other session. Findings indicated that nicotine deprivation reduced P3b amplitude (p<0.00001) during a three-stimulus oddball task independent of trait cognitive control. In contrast, nicotine deprivation reduced P3a only among participants who scored lower on measures of trait cognitive control. Implications for conceptualizing risk for nicotine dependence, and its treatment, are discussed.

The effects of recurrent episodes of depression on startle responses

Prior work suggests that major depression is associated with abnormal startle blink responses; however, only chronic or recurrent depression appears to be associated with this effect. The current study tested this hypothesis directly by examining whether recurrent major depression accounted for the anomalous startle seen in major depression using a sample of 515 female twins from the Minnesota Twin Family Study. Blink responses recorded at the age of 20 were examined in relation to number of episodes of depression prospectively assessed from ages 11 to 20. Results showed that only subjects who had experienced multiple episodes of depression showed abnormal startle responses. Subjects who had experienced just one episode of depression in their lifetime did not differ from controls. This lends additional support to the idea that recurrent depression may have a different etiological basis than nonrecurrent depression.

Early childhood predictors of early onset of smoking: a birth prospective study

OBJECTIVE

Early onset of smoking is associated with subsequent abuse of other substances and development of negative health outcomes. This study aimed to examine early life predictors of onset of smoking in an Australian young cohort.

METHODS

Data were from the Mater Hospital and University of Queensland Study of Pregnancy (MUSP), a population-based prospective birth cohort study (1981-2012). The present study is based on a cohort of 3714 young adults who self-reported smoking status and age of onset of smoking at the 21-year follow-up. Of these, data were available for 3039 on early childhood factors collected between the baseline and 14-year follow-up of the study.

RESULTS

Of 3714 young adults, 49.6% (49.9% males and 49.3% females) reported having ever smoked cigarettes. For those who had ever smoked, mean and median ages at first smoke were 15.5 and 16.0years, respectively. In multivariate Cox proportional hazard analysis mother's education, change in maternal marital status, maternal cigarette smoking and alcohol consumption, maternal depression and child externalizing when the child was 5years statistically significantly predicted early onset of smoking.

CONCLUSIONS

The data suggest that individuals exposed to personal and environmental risk factors during the early stage of childhood are at increased risk of initiation to cigarette smoking at an earlier age. Identification of the pathways of association between these early life factors and initiation to cigarette smoking may help reduce risk of tobacco smoking in adolescents and its adverse consequences.

Changes in genetic and environmental influences on trait anxiety ćfrom middle adolescence to early adulthood

BACKGROUND

Middle adolescence to early adulthood is an important developmental period for the emergence of anxiety. Genetically-influenced stable traits are thought to underlie internalizing psychopathology throughout development, but no studies have examined changes in genetic and environmental influences on trait anxiety during this period.

METHOD

A longitudinal twin study design was used to study same-sex twin pairs (485 monozygotic pairs, 271 dizygotic pairs) at three ages, 14, 18, and 21 years, to examine developmental shifts in genetic and environmental effects on trait anxiety.

RESULTS

The heritability of trait anxiety increased with age, particularly between ages 14 and 18, no significant new genetic influences emerged after age 14, and the genetic influences were highly correlated across the three ages, supporting developmentally stable genetic risk factors. The environmental effects shared by members of a family decreased in influence across adolescence, while the influence of environmental effects unique to each individual twin remained relatively stable over the course of development and were largely age-specific.

LIMITATIONS

The twin study design does not inform about specific genes and environmental risk factors.

CONCLUSIONS

Genetic influences increased in importance from middle to late adolescence but common genetic factors influenced trait anxiety across the three ages. Shared environmental influences decreased in importance and demonstrated negligible influence by late adolescence/early adulthood. Nonshared environmental effects were almost entirely age-specific. These findings support the importance of developmentally-sensitive interventions that target shared environmental factors prior to middle adolescence and shifting non-shared environmental risks at each age.

Genetic and environmental influences on the familial transmission of externalizing disorders in adoptive and twin offspring

IMPORTANCE

Twin-family studies have shown that parent-child resemblance on substance use disorders and antisocial behavior can be accounted for by the transmission of a general liability to a spectrum of externalizing disorders. Most studies, however, include only biological parents and offspring, which confound genetic and environmental transmission effects.

OBJECTIVE

To examine the familial transmission of externalizing disorders among both adoptive (genetically unrelated) and biological relatives to better distinguish genetic and environmental mechanisms of transmission.

DESIGN

Family study design wherein each family included the mother, father, and 2 offspring, including monozygotic twin, dizygotic twin, nontwin biological, and adoptive offspring. Structural equation modeling was used to estimate familial transmission effects and their genetic and environmental influences.

SETTING

Participants were recruited from the community and assessed at a university laboratory.

PARTICIPANTS

A total of 1590 families with biological offspring and 409 families with adoptive offspring. Offspring participants were young adults (mean age, 26.2 years).

MAIN OUTCOMES AND MEASURES

Symptom counts of conduct disorder, adult antisocial behavior, and alcohol, nicotine, and drug dependence. RESULTS There was a medium effect for the transmission of the general externalizing liability for biological parents (r = 0.27-0.30) but not for adoptive parents (r = 0.03-0.07). In contrast, adoptive siblings exhibited significant similarity on the general externalizing liability (r = 0.21). Biometric analyses revealed that the general externalizing liability was highly heritable (a2 = 0.61) but also exhibited significant shared environmental influences (c2 = 0.20).

CONCLUSIONS AND RELEVANCE

Parent-child resemblance for substance use disorders and antisocial behavior is primarily due to the genetic transmission of a general liability to a spectrum of externalizing disorders. Including adoptive siblings revealed a greater role of shared environmental influences on the general externalizing liability than previously detected in twin studies and indicates that sibling rather than parent-child similarity indexes important environmental risk factors for externalizing disorders.

Behavioral disinhibition and sexual risk behavior among adolescents and young adults in Malawi

BACKGROUND

While behavioral factors such as early age of sexual debut, inconsistent use of condoms and multiple sexual partners have been studied in Africa, less is known about how characteristics such as impulsivity and externalizing behaviors relate to HIV-related sexual risk-taking in that region. The purpose of this study was to develop a culturally adapted behavioral disinhibition index in a sample of adolescents and young adults in Malawi. We then sought to examine the relationship between the index and sexual risk behavior as measured by multiple sexual partners and number of lifetime sexual partners.

METHODS

Cross-sectional data were collected from 2342 participants in rural Malawi aged 15 to 29 years. We constructed a disinhibitory behavior score (DBS) using questions assessing disinhibitory behaviors. Bivariate analyses were conducted to assess the relationships among the individual DBS component behaviors. We utilized multivariable logistic regression to determine the association of the DBS with multiple sexual partners, and negative binomial regression to model the relationship between the DBS and number of lifetime sexual partners.

FINDINGS

Nearly all the DBS component behaviors were significantly associated in the bivariate analyses. The DBS was associated with having multiple sexual partners (OR 1.97; 95% CI 1.57-2.48) in the multivariable logistic regression analysis. Further, negative binomial regression results demonstrated that the DBS was associated with an increased number of lifetime sexual partners (OR 1.11; 95% CI 1.07-1.16).

CONCLUSIONS

HIV preventive programs in Africa should take into consideration disinhibitory behaviors that may be associated with sexual risk-taking. The DBS can be used as a simple tool to identify those who may be more likely to engage in these behaviors and provide useful information regarding which groups of individuals particularly need to be targeted for behavior change interventions.

Genetic and environmental influences on affiliation with deviant peers during adolescence and early adulthood

Adolescence and early adulthood is a time when peer groups become increasingly influential in the lives of young people. Youths exposed to deviant peers risk susceptibility to externalizing behaviors and related psychopathology. In addition to environmental correlates of deviant peer affiliation, a growing body of evidence has suggested that affiliation with deviant peers is heritable. This study examined the magnitude of genetic and environmental influences on affiliation with deviant peers, changes in the relative importance of these factors, and which of these factors contribute to the stability of affiliation across this critical developmental period using a longitudinal twin study design that assessed same-sex twins (485 monozygotic pairs, 271 dizygotic pairs) at 3 discrete ages: 15, 18, and 21 years of age. Biometric models revealed that genetic influences increased with age. New genetic influences appeared during late adolescence, and no new genetic influences emerged by age 21. Environmental influences shared by sibling pairs decreased with age, while the proportion of nonshared environmental effects unique to each individual remained relatively stable over the course of development. Shared environmental influences were largely age-overlapping, whereas nonshared environmental influences were largely age-specific. In summary, this study found variance in affiliation with deviant peers is explained by shared and nonshared environment effects as well as by genetic influences (46% by age 21), supporting the role of genetically influenced selection factors. The shared environment was almost exclusively responsible for the stability in late adolescence, while genetic influences were primarily responsible for stability in early adulthood.

Alcohol and tobacco use disorder comorbidity in young adults and the influence of romantic partner environments

BACKGROUND

Although there is considerable evidence that the development of tobacco dependence (TD) and that of alcohol use disorder (AUD) are intertwined, less is known about the comorbid development of these disorders. The present study examines tobacco dependence and alcohol use disorder comorbidity in young adulthood within the context of romantic partner relationships.

METHODS

Data were drawn from the Seattle Social Development Project, a contemporary, ethnically diverse, and gender balanced longitudinal panel including 808 participants. A typological person-centered approach was used to assign participants to four outcome groups: no disorder, tobacco dependence (TD) only, alcohol use disorder (AUD) only, and comorbid (both). Multinomial logistic regression was used to determine the association between partner general and substance-specific environments and single or dual alcohol and tobacco use disorder diagnosis in young adulthood (ages 24-33, n=628). Previous heavy alcohol and tobacco use were controlled for, as were dispositional characteristics, gender, ethnicity, adult SES, and adult depression.

RESULTS

Greater partner conflict increased the likelihood of being comorbid compared to having TD only or AUD only. Having a smoking partner increased the likelihood of being comorbid compared to having AUD only, but having a drinking partner did not significantly distinguish being comorbid from having TD only.

CONCLUSIONS

Findings demonstrated the utility of a comorbidity-based, person-centered approach and the influence of general and tobacco-specific, but not alcohol-specific, partner environments on comorbid alcohol and tobacco use disorders in young adulthood.

P300 amplitude reduction is associated with early-onset and late-onset pathological substance use in a prospectively studied cohort of 14-year-old adolescents

P3 amplitude reduction (P3AR) is associated with risk for adolescent-onset pathological substance use (PSU). In this longitudinal study, data from over 1,100 adolescent twins were used to examine P3AR in relation to early adolescent onset PSU (i.e., by age 14), late adolescent onset PSU (i.e., ages 14-18), misuse of different classes of substances (PSU-nicotine, PSU-alcohol, PSU-illicit), degree of PSU comorbidity, and gender differences. P3 amplitude was recorded at age 14 from two midline electrodes during a visual oddball paradigm. PSU was defined as meeting criteria for any symptom of a substance use disorder assessed using semistructured clinical interviews. P3AR was associated with degree of drug class comorbidity, early adolescent onset PSU for all three substance classes, and late adolescent onset PSU for alcohol and illicit PSU. Gender differences in P3AR were not statistically significant. These findings provide further evidence that P3AR indexes a nonspecific diathesis for adolescent-onset PSU.

Gene-environment correlation in the development of adolescent substance abuse: selection effects of child personality and mediation via contextual risk factors

We used a longitudinal twin design to examine selection effects of personality traits at age 11 on high-risk environmental contexts at age 14 and the extent to which these contexts mediated risk for substance abuse at age 17. Socialization at age 11 (willingness to follow rules and endorse conventional values) predicted exposure to contextual risk at age 14. Contextual risk partially mediated the effect of socialization on substance abuse, though socialization also had a direct effect. In contrast, boldness at age 11 (social engagement and assurance, thrill seeking, and stress resilience) also predicted substance abuse directly but was unrelated to contextual risk. There was substantial overlap in the genetic and shared environmental influences on socialization and contextual risk, and genetic risk in socialization contributed to substance abuse indirectly via increased exposure to contextual risk. This suggests that active gene-environment correlations related to individual differences in socialization contributed to an early, high-risk developmental trajectory for adolescent substance abuse. In contrast, boldness appeared to index an independent and direct genetic risk factor for adolescent substance abuse.

An examination of the representativeness assumption for twin studies of eating pathology and internalizing symptoms

Little research has investigated whether the twin representativeness assumption (that results from twin research generalize to singletons) holds for eating pathology and internalizing symptoms. This study compared disordered eating, depression, and anxiety among young adult female twins versus singletons. Participants included 292 twins and 997 singletons in three samples. Questionnaires included the Minnesota Eating Behavior Survey, Eating Disorder Examination Questionnaire, Beck Depression Inventory, and State-Trait Anxiety Inventory. We examined mean differences between twins' and singletons' scores, after adjusting for age, body mass index, and ethnicity. We found statistically significant mean differences on psychopathology, with twins reporting less disordered eating and internalizing symptoms compared with singletons. Effect sizes of these mean differences were small to moderate. Our results suggest that twins report less disordered eating and internalizing symptoms than singletons, which, combined with the generally small effect sizes, indicate that results from twin samples generalize to singletons.

Characterizing electrodermal response habituation: a latent class approach with application to psychopathology

Response habituation is a fundamental form of nonassociative learning, yet there are substantial individual differences in its electrodermal manifestation. We employed a latent class analysis to identify discrete groups of electrodermal responders to a series of loud tones. We also evaluated whether heterogeneity in responsiveness was associated with lifetime prevalence of externalizing psychopathology and major depression. Participants were community-recruited men (N = 1,141) who underwent a standard habituation paradigm. A latent class analysis resulted in the identification of four electrodermal populations: rapid habituators, habituators, and two classes that showed weak response habituation, but differed markedly in their amplitude profiles. Relative to rapid habituators, members of slower habituating classes were less likely to receive lifetime diagnoses of antisocial personality disorder and substance dependence. Further research using this analytical strategy could help identify the functional significance of individual differences in habituation.

The moderating effect of family involvement on substance use risk factors in adolescents with severe emotional and behavioral challenges

OBJECTIVE

The current study longitudinally examined the moderating effects of family involvement, which previous research has shown to be a protective factor against adolescents' substance use involvement, on the associations between internalizing and externalizing problems, respectively, and substance use (alcohol, marijuana, and tobacco) and problems in a unique sample of adolescents with severe emotional and behavioral problems.

METHOD

Adolescents (n=4786) and their parents were assessed at three waves over a 1-year period as part of the SAMHSA funded Comprehensive Community Mental Health Initiative (CMHI). Multilevel growth curve models were estimated using Hierarchical Linear Modeling (HLM) to examine the associations between time-varying internalizing and externalizing problems, respectively, and substance use involvement over time as a function of family involvement at baseline.

RESULTS

Results supported the hypothesis that family involvement protects against adolescent substance use involvement by buffering the adverse effects of both internalizing and externalizing problems. Specifically, for alcohol use, family involvement buffered the negative effects of high externalizing problems. For tobacco use, family involvement buffered the negative effects of both internalizing and externalizing problems, respectively. For substance use problems, family involvement buffered the effects of only internalizing problems. Family involvement did not moderate effects of emotional and behavioral problems on marijuana use, however, a significant main effect was observed such that family involvement was negatively related to marijuana use.

CONCLUSIONS

Results suggest that the beneficial effects of family involvement on at-risk adolescents' substance use involvement are dependent on the type of emotional and behavioral problems the adolescent experiences as well as the type of substance the adolescent uses. Implications for family- and adolescent-focused treatment are discussed.

Dimensions of disinhibited personality and their relation with alcohol use and problems

Although alcohol use disorders (AUDs) have been associated with different aspects of disinhibited personality and antisociality, less is known about the specific relationships among different domains of disinhibited personality, antisociality, alcohol use, and alcohol problems. The current study was designed to address three goals, (i) to provide evidence of a three-factor model of disinhibited personality (comprised of impulsivity [IMP], risk taking/low harm avoidance [RTHA], excitement seeking [ES]), (ii) to test hypotheses regarding the association between each dimension and alcohol use and problems, and (iii) to test the hypothesis that antisociality (social deviance proneness [SDP]) accounts for the direct association between IMP and alcohol problems, while ES is directly related to alcohol use. Measures of disinhibited personality IMP, RTHA, ES and SDP and alcohol use and problems were assessed in a sample of young adults (N=474), which included a high proportion of individuals with AUDs. Confirmatory factor analyses supported a three-factor model of disinhibited personality reflecting IMP, RTHA, and ES. A structural equation model (SEM) showed that IMP was specifically associated with alcohol problems, while ES was specifically associated with alcohol use. In a second SEM, SDP accounted for the majority of the variance in alcohol problems associated with IMP. The results suggest that aspects of IMP associated with SDP represent a direct vulnerability to alcohol problems. In addition, the results suggest that ES reflects a specific vulnerability to excessive alcohol use, which is then associated with alcohol problems, while RTHA is not specifically associated with alcohol use or problems when controlling for IMP and ES.

Disentangling the relative contribution of parental antisociality and family discord to child disruptive disorders

A number of familial risk factors for childhood disruptive disorders have been identified. However, many of these risk factors often co-occur with parental antisociality, which by itself may account for both the familial risk factors and the increased likelihood of offspring disruptive behavior disorders (DBDs). The current study aimed to examine the association of parenting behaviors, marital conflict, and divorce with child DBDs while accounting for (a) coparent parenting behaviors, and (b) parental adult antisocial behavior (AAB). A series of regressions tested the association between family-level variables (namely, parent-child relationship quality, parental willingness to use physical punishment, marital adjustment, and history of divorce) and DBDs (attention deficit hyperactivity disorder, conduct disorder, and oppositional defiant disorder) alone and after statistically adjusting for coparent variables and parental AAB. Results indicated that parents with AAB were more likely to engage in various forms of maladaptive parenting, to divorce, and to have conflictual marriages. Maladaptive parenting, marital conflict, and divorce were associated with heightened rates of child DBDs, and these associations persisted after adjusting for coparent parenting and parental AAB. Finally, the mother's parenting behaviors had a higher impact on child DBDs than the father's parenting behaviors. Thus, familial variables continue to have an effect on childhood DBDs even after accounting for confounding influences. These variables should be a focus of research on etiology and intervention.

The dysregulated cluster in personality profiling research: longitudinal stability and associations with bulimic behaviors and correlates

Among cluster analytic studies of the personality profiles associated with bulimia nervosa, a group of individuals characterized by emotional lability and behavioral dysregulation (i.e., a dysregulated cluster) has emerged most consistently. However, previous studies have all been cross-sectional and mostly used clinical samples. This study aimed to replicate associations between the dysregulated personality cluster and bulimic symptoms and related characteristics using a longitudinal, population-based sample. Participants were females assessed at ages 17 and 25 from the Minnesota Twin Family Study, clustered based on their personality traits. The Dysregulated cluster was successfully identified at both time points and was more stable across time than either the Resilient or Sensation Seeking clusters. Rates of bulimic symptoms and related behaviors (e.g., alcohol use problems) were also highest in the dysregulated group. Findings suggest that the dysregulated cluster is a relatively stable and robust profile that is associated with bulimic symptoms.

How phenotype and developmental stage affect the genes we find: GABRA2 and impulsivity

CONTEXT

The detection and replication of genes involved in psychiatric outcome has been notoriously difficult. Phenotypic measurement has been offered as one explanation, although most of this discussion has focused on problems with binary diagnoses.

OBJECTIVE

This article focuses on two additional components of phenotypic measurement that deserve further consideration in evaluating genetic associations: (1) the measure used to reflect the outcome of interest, and (2) the developmental stage of the study population. We focus our discussion of these issues around the construct of impulsivity and externalizing disorders, and the association of these measures with a specific gene, GABRA2.

DESIGN, SETTING, AND PARTICIPANTS

Data were analyzed from the Collaborative Study on the Genetics of Alcoholism Phase IV assessment of adolescents and young adults (ages 12-26; N = 2,128).

MAIN OUTCOME MEASURES

Alcohol dependence, illicit drug dependence, childhood conduct disorder, and adult antisocial personality disorder symptoms were measured by psychiatric interview; Achenbach youth/adult self-report externalizing scale; Zuckerman Sensation-Seeking scale; Barratt Impulsivity scale; NEO extraversion and consciousness.

RESULTS

GABRA2 was associated with subclinical levels of externalizing behavior as measured by the Achenbach in both the adolescent and young adult samples. Contrary to previous associations in adult samples, it was not associated with clinical-level DSM symptom counts of any externalizing disorders in these younger samples. There was also association with sensation-seeking and extraversion, but only in the adolescent sample. There was no association with the Barratt impulsivity scale or conscientiousness.

CONCLUSIONS

Our results suggest that the pathway by which GABRA2 initially confers risk for eventual alcohol problems begins with a predisposition to sensation-seeking early in adolescence. The findings support the heterogeneous nature of impulsivity and demonstrate that both the measure used to assess a construct of interest and the age of the participants can have profound implications for the detection of genetic associations.

The effect of general and drug-specific family environments on comorbid and drug-specific problem behavior: a longitudinal examination

Previous research has shown that the development of alcohol and tobacco dependence is linked and that both are influenced by environmental and intrapersonal factors, many of which likely interact over the life course. The present study examines the effects of general and alcohol- and tobacco-specific environmental influences in the family of origin (ages 10-18) and family of cohabitation (ages 27-30) on problem behavior and alcohol- and tobacco-specific outcomes at age 33. General environmental factors include family management, conflict, bonding, and involvement. Alcohol environment includes parental alcohol use, parents' attitudes toward alcohol, and children's involvement in family drinking. Tobacco-specific environment is assessed analogously. Additionally, analyses include the effects of childhood behavioral disinhibition, initial behavior problems, and age 18 substance use. Analyses were based on 469 participants drawn from the Seattle Social Development Project (SSDP) sample. Results indicated that (a) environmental factors within the family of origin and the family of cohabitation are both important predictors of problem behavior at age 33; (b) family of cohabitation influences partially mediate the effects of family of origin environments; (c) considerable continuity exists between adolescent and adult general and tobacco (but not alcohol) environments; age 18 alcohol and tobacco use partially mediates these relationships; and (d) childhood behavioral disinhibition contributed to age 33 outcomes, over and above the effects of family of cohabitation mediators. Implications for preventive interventions are discussed.

Association between P3 event-related potential amplitude and externalizing disorders: a time-domain and time-frequency investigation of 29-year-old adults

This study determined whether time-domain P3 amplitude and time-frequency principal component (TF-PC) reductions are present in adulthood (age 29) when participants have largely passed through the age of heaviest substance misuse. Participants were assessed from age 17 through 29 for lifetime externalizing (EXT) disorders. EEG comparisons from three topographic regions were examined for P3 amplitude and TF-PCs at delta and theta frequency ranges. Significant P3 amplitude reductions were found in those with EXT for both regional and site-Pz analyses, with stronger effects observed the greater the EXT comorbidity. Reductions were also observed in all eight TF-PCs extracted, with a delta component yielding frontal effects not apparent in the time domain. Overall, results suggest that these brain measures continue, at age 29, to provide effective indices of EXT that potentially tap a neural substrate related to behavioral disinhibition.