Common Liabilities in Internalizing Symptoms and Cigarette Use in Adolescence

INTRODUCTION

Substance use and mood disorders account for about 10% of the global burden of disease and, among adolescents, are a significant source of disability. The present study examined whether additive genetic or shared environmental factors influenced the covariance of internalizing symptoms and cigarette use during adolescence when both of these problems begin to increase.

AIMS AND METHODS

We used data (n = 1230 pairs of twins) from the Virginia Twin Study of Adolescent Behavioral Development (mean age = 15.3) to decompose the variance of internalizing symptoms, cigarette initiation, and quantity of cigarettes smoked in a variance decomposition model that included a beta coefficient to allow for estimates of cigarette initiation to influence quantity of cigarettes smoked.

RESULTS

In biometric models we were able to equate all parameter estimates by sex. After identifying the best fitting model, parameter estimates were calculated and the significance of overlapping paths between internalizing symptoms and cigarette initiation were tested. After accounting for the genetic architecture of cigarette initiation and quantity smoked, the covariance between internalizing symptoms and cigarette use was accounted for by sex-specific shared and unique environmental factors.

CONCLUSIONS

Among adolescents, the overlap in risk factors between internalizing symptoms and cigarette use is because of non-genetic, environmental factors. Further exploration of the environmental sources of variance involved in the onset of adolescents internalizing symptoms and cigarette use is warranted.

IMPLICATIONS

We find that during adolescence common environmental factors influence the association between internalizing symptoms and cigarette use. Correlated vulnerabilities because of environmental sources between internalizing and cigarette use may be open to intervention and likely will influence the progression of internalizing and cigarette use.

Transancestral GWAS of alcohol dependence reveals common genetic underpinnings with psychiatric disorders

Liability to alcohol dependence (AD) is heritable, but little is known about its complex polygenic architecture or its genetic relationship with other disorders. To discover loci associated with AD and characterize the relationship between AD and other psychiatric and behavioral outcomes, we carried out the largest genome-wide association study to date of DSM-IV-diagnosed AD. Genome-wide data on 14,904 individuals with AD and 37,944 controls from 28 case-control and family-based studies were meta-analyzed, stratified by genetic ancestry (European, n = 46,568; African, n = 6,280). Independent, genome-wide significant effects of different ADH1B variants were identified in European (rs1229984; P = 9.8 × 10-13) and African ancestries (rs2066702; P = 2.2 × 10-9). Significant genetic correlations were observed with 17 phenotypes, including schizophrenia, attention deficit-hyperactivity disorder, depression, and use of cigarettes and cannabis. The genetic underpinnings of AD only partially overlap with those for alcohol consumption, underscoring the genetic distinction between pathological and nonpathological drinking behaviors.

Childhood socioeconomic status and longitudinal patterns of alcohol problems: Variation across etiological pathways in genetic risk

Childhood socioeconomic status (SES) is an important aspect of early life environment associated with later life health/health behaviors, including alcohol misuse. However, alcohol misuse is modestly heritable and involves differing etiological pathways. Externalizing disorders show significant genetic overlap with substance use, suggesting an impulsivity pathway to alcohol misuse. Alcohol misuse also overlaps with internalizing disorders, suggesting alcohol is used to cope. These differing pathways could lead to different patterns over time and/or differential susceptibility to environmental conditions, such as childhood SES. We examine whether: 1) genetic risk for externalizing and internalizing disorders influence trajectories of alcohol problems across adolescence to adulthood, 2) childhood SES alters genetic risk these disorders on trajectories of alcohol problems, and 3) these patterns are consistent across sex. We find modest evidence of gene-environment interaction. Higher childhood SES increases the risk of alcohol problems in late adolescence/early adulthood, while lower childhood SES increases the risk of alcohol problems in later adulthood, but only among males at greater genetic risk of externalizing disorders. Females from lower SES families with higher genetic risk of internalizing or externalizing disorders have greater risk of developing alcohol problems.

Cross-Lagged Analysis of Interplay Between Differential Traits in Sibling Pairs: Validation and Application to Parenting Behavior and ADHD Symptomatology

Understanding the factors that contribute to behavioral traits is a complex task, and partitioning variance into latent genetic and environmental components is a useful beginning, but it should not also be the end. Many constructs are influenced by their contextual milieu, and accounting for background effects (such as gene-environment correlation) is necessary to avoid bias. This study introduces a method for examining the interplay between traits, in a longitudinal design using differential items in sibling pairs. The model is validated via simulation and power analysis, and we conclude with an application to paternal praise and ADHD symptoms in a twin sample. The model can help identify what type of genetic and environmental interplay may contribute to the dynamic relationship between traits using a cross-lagged panel framework. Overall, it presents a way to estimate and explicate the developmental interplay between a set of traits, free from many common sources of bias.

Potentially Traumatic Events, Posttraumatic Stress Disorder, and Depression among Adults in Puerto Rico

The aims of the current study were to examine the prevalence of potentially traumatic events (PTEs), posttraumatic stress disorder (PTSD; data available in males only), and depressive symptoms in a Puerto Rican sample of 678 adult caretakers (50% female) of twins participating in the Puerto Rican Infant Twin Study. The World Health Organization Composite International Diagnostic Interview version 3.0 (CIDI 3.0) was utilized to assess rates of PTEs, PTSD, and depression among male participants while an abbreviated version of the CIDI 3.0 and the Mood and Feelings Questionnaire were administered to females to assess PTEs and depressive symptoms. Significantly more males than females reported exposure to a PTE (76.6% vs. 44.2%, χ(2) = 64.44, p < 0.001). In males, endorsement of multiple PTEs was associated with increased level of PTSD symptomatology (β = 0.33, p < 0.001). With regard to depression, a similar dose-response relationship was found in both males and females, with depressive symptoms increasing as number of PTEs increased (βs = 0.15, 0.16, ps < 0.05). Exposure to an attack with a weapon was significantly associated with increased depression symptoms in both males and females (βs = 0.24, 0.20, ps < 0.01, respectively). These findings highlight the need for identification of putative risk and resilience factors among PTE-exposed individuals in Puerto Rico.

Factors Influencing Men's Interest in Gene Testing for Prostate Cancer Susceptibility

Interest in genetic testing for inherited cancer susceptibility is high in the general population. Women at risk for BRCA1 and BRCA2 mutations represent the best-studied population undergoing genetic testing for cancer susceptibility. However, it is unclear whether factors influencing interest in genetic testing in women are directly applicable to men. We designed a study to examine factors associated with men's interest in genetic testing to identify prostate cancer susceptibility. Our sample consisted of 267 men present in waiting rooms of a urology clinic in an urban area. We examined whether the concept of "monitoring" could be used to predict the interest of men in a genetic test for prostate cancer susceptibility. Our results indicated that "monitoring" trait was positively associated with interest in genetic testing in these men, but principally for patients rather than nonpatients. Moreover we found that monitoring was associated with over estimation of risk in those men with prostate cancer. Other factors found to influence interest in genetic testing included recommendation by a doctor, family history of prostate cancer, and cost. This study indicated that interest in genetic testing and estimation of risk is influenced by a complex interaction between both psychological factors (monitoring) and nonbehavioral factors (such as patient status, cost, and doctor recommendation).

Age of onset and the subclassification of conduct/dissocial disorder

BACKGROUND

Conduct Disorder (CD) is a markedly heterogeneous psychiatric condition. Moffitt (1993) proposed that subclassification of CD should be according to age of onset. Our goals were to compare childhood-onset and adolescent-onset CD in terms of differences in phenotypic risk factors, genetic analyses, and factors associated with the persistence of antisocial behavior into young adulthood.

METHODS

The data are from the Virginia Twin Study of Adolescent Behavioral Development (VTSABD) and Young Adult Follow-Up (YAFU). Childhood-onset CD was defined as CD beginning at or before age 11. Adolescent-onset CD was defined as having CD onset between ages 14 and 17. These subgroups were compared on ADHD, young adult antisocial behavior (ASB), family dysfunction, and parental depression. Genetic analyses compare childhood-onset and adolescent-onset CD, as well as their cooccurrence with ADHD and ASB. Finally, predictors of persistence were examined.

RESULTS

Childhood-onset CD was significantly associated with ADHD, ASB, family dysfunction, and parental depression. Adolescent-onset CD was marginally associated with parental depression (p = .05) but not with any of the other risk factors. Univariate genetic models showed that both childhood-onset and adolescent-onset CD involve a large genetic liability accounting for 62% and 65% of the variance, respectively. A common genetic factor (as well as an ADHD-specific factor) accounted for the cooccurrence of childhood-onset CD and ADHD. The cooccurrence of childhood-onset CD and ASB are reflected by a common genetic factor with genetic specific effects on ASB. There was no etiological link between adolescent-onset CD and either ADHD or ASB. Both ADHD and family dysfunction were significantly associated with the persistence of antisocial behavior into young adulthood.

CONCLUSIONS

Phenotypic findings differentiated between childhood-onset and adolescent-onset CD. ADHD and family dysfunction predicted persistence of antisocial behavior into young adulthood.

Has the “Equal Environments” Assumption Been Tested in Twin Studies?

Arecurring criticism of the twin method for quantifying genetic and environmental components of human differences is the necessity of the so-called “equal environments assumption” (EEA) (i.e., that monozygotic and dizygotic twins experience equally correlated environments). It has been proposed to test the EEA by stratifying twin correlations by indices of the amount of shared environment. However, relevant environments may also be influenced by genetic differences. We present a model for the role of genetic factors in niche selection by twins that may account for variation in indices of the shared twin environment (e.g., contact between members of twin pairs). Simulations reveal that stratification of twin correlations by amount of contact can yield spurious evidence of large shared environmental effects in some strata and even give false indications of genotype x environment interaction. The stratification approach to testing the equal environments assumption may be misleading and the results of such tests may actually be consistent with a simpler theory of the role of genetic factors in niche selection.

The impact of environmental experiences on symptoms of anxiety and depression across the life span

Symptoms of anxiety and depression are relatively stable over time. Can this stability be explained by genetic influences, or is it caused by the long-lasting effects of accumulating environmental experiences? To address this question, we analyzed longitudinally assessed symptoms of anxiety and depression in eight samples of monozygotic twins of widely varying ages. These samples were drawn from American and European population-based registries. Using hierarchical linear modeling, we examined individual differences and individual changes in the level of symptoms over time. This method enabled us to decompose the variance into the predictable variance shared by both members of each pair of twins, the differences between individuals within pairs, and the residual variance. We then modeled how these components of individual variation changed over time. Within pairs, the twins' predicted levels of symptoms increasingly diverged from childhood until late adulthood, at which point the divergence ceased. By middle adulthood, environmental experiences contributed substantially to stable and predictable interindividual differences in levels of anxiety and depression.

The relationship between separation anxiety and impairment

The goal of this study was to characterize the contemporaneous and prognostic relationship between symptoms of separation anxiety disorder (SAD) and associated functional impairment. The sample comprised n=2067 8-16-year-old twins from a community-based registry. Juvenile subjects and their parents completed a personal interview on two occasions, separated by an average follow-up period of 18 months, about the subject's current history of SAD and associated functional impairment. Results showed that SAD symptoms typically caused very little impairment but demonstrated significant continuity over time. Older youth had significantly more persistent symptoms than younger children. Prior symptom level independently predicted future symptom level and diagnostic symptom threshold, with and without impairment. Neither diagnostic threshold nor severity of impairment independently predicted outcomes after taking account of prior symptom levels. The results indicate that impairment may index current treatment need but symptom levels provide the best information about severity and prognosis.

Heterogeneity among juvenile antisocial behaviours: findings from the Virginia Twin Study of Adolescent Behavioural Development

The examination of heterogeneity in antisocial behaviour was accomplished by applying latent class analytic methods to multivariate categorical data on 389 same-sex male twins, aged 11 to 16 from the Virginia Twin Study of Adolescent Behavioural Development (VTSABD). The data included multiple measures of oppositional and conduct disorder, attention deficit disorder, hyperactivity, impulsivity, reading disability and anxiety from mother, teacher, and child report from both questionnaire and interview (child and adult psychiatric assessment; CAPA). A latent four-class model provided a good fit to the data and yielded four phenotypically and aetiologically distinct latent classes: (1) a non-symptomatic class influenced by both additive genetic and shared environmental factors; (2) a hyperactivity-conduct disturbance class accounted for by both additive and non-additive genetic effects; (3) a 'pure' conduct disturbance class with a very strong shared environmental component; and (4) a multisymptomatic class explained entirely by the additive effect of the genes. Further characterization of these four latent classes by age of the child and parental psychiatric history is also shown.

A Children of Twins Study of parental divorce and offspring psychopathology

BACKGROUND

Although parental divorce is associated with increased substance use and internalizing problems, experiencing the separation of one's parents may not cause these outcomes. The relations may be due to genetic or environmental selection factors, characteristics that lead to both marital separation and offspring functioning.

METHOD

We used the Children of Twins (CoT) Design to explore whether unmeasured genetic or environmental factors related to the twin parent, and measured characteristics of both parents, account for the association between parental divorce and offspring substance use and internalizing problems.

RESULTS

The association between parental divorce and offspring substance use problems remained robust when controlling for genetic and environmental risk from the twin parent associated with parental divorce, and measured characteristics of both parents. The results do not prove, but are consistent with, a causal connection. In contrast, the analyses suggest that shared genetic liability in parents and their offspring accounts for the increased risk of internalizing problems in adult offspring from divorced families.

CONCLUSIONS

The study illustrates that unmeasured genetic and environmental selection factors must be considered when studying parental divorce. In explaining associations between parental divorce and young-adult adjustment, our evidence suggests that selection versus causal mechanisms may operate differently for substance abuse (a causal relation) and internalizing problems (an artifact of selection). The CoT design only controls for the genetic and environmental characteristics of one parent; thus, additional genetically informed analyses are needed.

Application of Bayesian Inference using Gibbs Sampling to Item-Response Theory Modeling of Multi-Symptom Genetic Data

Several "genetic" item-response theory (IRT) models are fitted to the responses of 1086 adolescent female twins to the 33 multi-category item Mood and Feeling Questionnaire relating to depressive symptomatology in adolescence. A Markov-chain Monte Carlo (MCMC) algorithm is used within a Bayesian framework for inference using Gibbs sampling, implemented in the program WinBUGS 1.4. The final model incorporated separate genetic and non-shared environmental traits ("A and E") and item-specific genetic effects. Simpler models gave markedly poorer fit to the observations judged by the deviance information criterion (DIC). The common genetic factor showed major loadings on melancholic items, while the environmental factor loaded most highly on items relating to self-deprecation. The MCMC approach provides a convenient and flexible alternative to Maximum Likelihood for estimating the parameters of IRT models for relatively large numbers of items in a genetic context. Additional benefits of the IRT approach are discussed including the estimation of latent trait scores, including genetic factor scores, and their sampling errors.

Genetic and Environmental Influences on the Relative Timing of Pubertal Change

A multicategory item-response theory model was developed to characterize developmental changes in three items relating to the assessment of puberty in adolescent twin girls and boys. The model allowed for the fixed effects of age on probability of endorsing the responses and for the random effects of individual differences on the timing of pubertal changes relative to chronological age. In girls, the model was applied three-wave data on twin pairs (N = 414 female monozygotic [MZ] and 197 female dizygotic [DZ] pairs) and female twins from boy-girl pairs (N = 300 twins) from the Virginia Twin Study of Adolescent Behavioral Development. In boys, the data comprised 318 MZ and 185 DZ pairs and 297 male twins from boy-girl pairs. A total of 3172 and 2790 individual twin assessments were available in girls and boys, respectively, spanning ages 8-17 years. The availability of twin data allows the contributions of genes, the shared environment and individual unique environmental experiences to be resolved in the relative timing of pubertal changes. Parameters of the mixed model including fixed effects of age and random effects of genes and environment were estimated by Markov Chain Monte Carlo simulations using the BUGS algorithm for Gibbs sampling. The estimated standard deviation of random differences in the timing of puberty relative to age was 0.96 years in girls and 1.01 years in boys. The estimated intraclass correlations for the relative timing of pubertal changes were 0.99 +/-0.01 in MZ girls, 0.52 +/-0.02 in DZ girls, 0.88 +/-0.04 in MZ boys and 0.44+/-0.02 in DZ boys, indicating a very large contribution of genetic factors to the relative timing of pubertal change in both sexes. Additive genetic factors account for an estimated 96.3+/-3.3% of the total variance in random effects in girls and 88.0+/-3.6% in boys. Shared environmental influences account for 3.6+/-3.4% in girls and 0% in boys. In girls, nonshared environmental effects explain 0.1+/-0.1% of the total residual variance. The comparable figure in boys is 12.0+/-3.6%.

Informant disagreement for separation anxiety disorder

OBJECTIVE

To characterize informant disagreement for separation anxiety disorder (SAD).

METHOD

The sample comprised 2,779 8- to 17-year-old twins from a community-based registry. Children and their parents completed a personal interview about the child's psychiatric history. Parents completed a personal interview about their own psychiatric history and a questionnaire about their marital relationship.

RESULTS

Informant agreement for SAD ranged between chance and extremely poor. Most cases of SAD were diagnosed by interview with only one informant. SAD diagnosed only by child interview was associated with an increased odds of father-rated oppositional defiant disorder, and vice versa. SAD diagnosed only by parent interview was predicted by the parental informant's history of antisocial personality disorder. SAD diagnosed only by paternal interview was also predicted by mother-rated marital conflict and dissatisfaction.

CONCLUSIONS

Parents and children rarely agree about the presence of any level of child separation anxiety. A symptom "or-rule" mostly indexes diagnoses based on interview with only one informant, but the relative validity of such diagnoses remains unclear.

Has the "Equal Environments" Assumption Been Tested in Twin Studies?

A recurring criticism of the twin method for quantifying genetic and environmental components of human differences is the necessity of the so-called "equal environments assumption" (EEA) (i.e., that monozygotic and dizygotic twins experience equally correlated environments). It has been proposed to test the EEA by stratifying twin correlations by indices of the amount of shared environment. However, relevant environments may also be influenced by genetic differences. We present a model for the role of genetic factors in niche selection by twins that may account for variation in indices of the shared twin environment (e.g., contact between members of twin pairs). Simulations reveal that stratification of twin correlations by amount of contact can yield spurious evidence of large shared environmental effects in some strata and even give false indications of genotype x environment interaction. The stratification approach to testing the equal environments assumption may be misleading and the results of such tests may actually be consistent with a simpler theory of the role of genetic factors in niche selection.

Resolving multiple epigenetic pathways to adolescent depression

BACKGROUND

Genotype x environment interaction (G x E) arises when genes influence sensitivity to the environment. G x E is easily recognized in experimental organisms that permit randomization of genotypes over fixed environmental treatments. Genotype-environment correlation (rGE) arises when genetic effects create or evoke exposure to environmental differences. Simultaneous analysis of G x E and such 'active' or 'evocative' rGE in humans is intractable with linear structural models widely used in behavioral genetics because environments are random effects often correlated with genotype. The causes of the environmental variation, therefore, need to be modeled at the same time as the primary outcome.

METHODS

A Markov Chain Monte Carlo approach is used to resolve three distinct pathways involving genes and life events affecting the development of post-pubertal depression in female twins and its relationship to pre-pubertal anxiety: 1) the main of genes and environment; 2) the interaction of genes and environment (G x E); and 3) genotype-environment correlation (rGE).

RESULTS

A model including G x E and rGE in addition to the main effects of genes and environment yields significant estimates of the parameters reflecting G x E and rGE. Omission of either G x E or rGE leads to overestimation of the effects of the measured environment and the unique random environment within families.

CONCLUSIONS

1) Genetic differences in anxiety create later genetic differences in depression; 2) genes that affect early anxiety increase sensitivity (G x E) to adverse life events; 3) genes that increase risk to early anxiety increase exposure to depressogenic environmental influences (rGE). Additional genetic effects, specific to depression, further increase sensitivity to adversity. Failure to take into account the effects of G x E and rGE will lead to misunderstanding how genes and environment affect complex behavior.

Genetic and environmental risk factors in adolescent substance use

BACKGROUND

The present study was undertaken with the goal of understanding the causes of association between substance use and both conduct disturbance (CD) and depression in adolescent boys and girls.

METHOD

Multivariate genetic structural equation models were fitted to multi-informant, multi-wave, longitudinal data collected in extensive home interviews with parents and children with respect to 307 MZ male, 392 MZ female, 185 DZ male, and 187 DZ female, same-sex twin pairs aged 12-17 years from the Virginia Twin Study of Adolescent Behavioral Development (VTSABD).

RESULTS

Although conduct disturbance and depression were moderately associated with substance use, the pattern of genetic and environmental risk differed for males and females and across the two disorders. Genetic factors were predominant in girls' substance use whereas boys' use was mediated primarily by shared environmental factors reflecting family dysfunction and deviant peers. The patterns of correlations across the two waves of the study were consistent with conduct disturbance leading to substance use in both males and females, but depression leading to smoking, drug use and, to a lesser extent, alcohol use in girls.

CONCLUSIONS

The comorbidity between substance use and depression, and between substance use and conduct disturbance in childhood/adolescence, probably reflects rather different mediating mechanisms--as well as a different time frame, with conduct disturbance preceding substance use but depression following it. In both, the co-occurrence partially reflected a shared liability but, in girls, genetic influences played an important role in the comorbidity involving depression, whereas in both sexes (but especially in boys) environmental factors played a substantial role. The extent to which these differences reflect genuine differences in the causal mechanisms underlying substance use and CD/depression in boys and girls revealed in the present analysis awaits replication from studies of other general population samples.

Depression scale scores in 8-17-year-olds: effects of age and gender

BACKGROUND

The excess of unipolar depression in females emerges in adolescence. However, studies of age effects on depression scale scores have produced divergent estimates of changes from childhood to adolescence.

METHOD

We explored possible reasons for this discrepancy in two large, longitudinal samples of twins and singletons aged 8-17.

RESULTS

There were no differences between twins and singletons in their scores on the Short Mood and Feelings Questionnaire (SMFQ), a 13-item self-report depression scale. SMFQ scores for boys fell over this age-range, while those for girls fell from age 9 to age 11 and then increased from age 12 to age 17. The mean scores of girls under 12 and those 12 and over differed by only around one-fifth of a standard deviation. However, given the non-normal distribution of the scores, a cut point that selected the upper 6% of scores created the expected female:male ratio of 2:1.

CONCLUSIONS

Implications for future research on adolescent depression are discussed.

Gene-environment interplay in relation to emotional and behavioral disturbance

The conceptual and methodological issues involved in the study of gene-environment correlations (rGE) and interactions (GxE) are discussed in historical context. Quantitative genetic findings are considered with respect to rGE and GxE in relation to emotional and behavioral disturbance. Key conceptual and substantive implications are outlined in relation to both genetic and environmental risk mediation, with a brief note on evolutionary considerations.

Child psychiatric symptoms and psychosocial impairment: relationship and prognostic significance

BACKGROUND

Relatively little is known about the relationships between psychiatric symptoms, diagnosis and psychosocial impairment.

AIMS

To examine these contemporaneous relationships and prognostic significance in a large general population sample.

METHOD

Symptoms of major depression, conduct and oppositional defiant disorders were assessed by interview in two waves of the Virginia Twin Study of Adolescent behavioural Development (2800 children aged 8-16 years).

RESULTS

Many children below the DSM-III-R diagnostic threshold, especially for depression, had symptom-related impairment, whereas many children reaching the symptom threshold for conduct and oppositional defiant disorders were little impaired. Impairment score was linearly related to symptom count, with no evidence of any additional impairment at the diagnostic threshold. For depression, only symptoms predicted later symptoms and diagnosis. For conduct and oppositional defiant disorders, impairment was additionally predictive of later symptoms and diagnosis.

CONCLUSIONS

Impairment, in addition to symptoms, is important for both nosology and prognosis.

Genetic moderation of environmental risk for depression and anxiety in adolescent girls

BACKGROUND

There is huge individual variation in people's response to negative life events.

AIMS

To test the hypothesis that genetic factors moderate susceptibility to the environmentally mediated risks associated with negative life events.

METHOD

The Virginia Twin Study of Adolescent Behavioral Development (VTSABD) was used to study the effects of independent life events (assessed from maternal interview) on depression/anxiety (assessed from child interview) in 184 same-gender female twin pairs, aged 14--7 years, measured on two occasions.

RESULTS

There was no genetic effect on the independent negative life events studied. A significant gene-environment interaction was found using structural equation modelling. There was no effect of independent life events on adolescents' depression in the absence of parental emotional disorder, but a significant effect in its presence.

CONCLUSIONS

There is an environmentally mediated effect of life events on depression/anxiety. Genetic factors play a significant role in individual differences in susceptibility to these environmentally mediated risks.

Childhood sexual abuse and adult psychiatric and substance use disorders in women: an epidemiological and cotwin control analysis

BACKGROUND

Women who report childhood sexual abuse (CSA) are at increased risk for developing psychiatric disorders in adulthood. What is the diagnostic specificity and cause of this association?

METHODS

In a population-based sample of 1411 female adult twins, 3 levels of CSA were assessed by self-report and cotwin report: nongenital, genital, and intercourse. Interviews with twins and parents assessed family background and diagnoses of psychiatric and substance dependence disorders. Odds ratios (ORs) were calculated by logistic regression.

RESULTS

By self-report, 30.4% reported any CSA and 8.4% reported intercourse. Self-reported CSA was positively associated with all disorders, the highest ORs being seen with bulimia and alcohol and other drug dependence. The ORs were modest and often nonsignificant with nongenital CSA and increased with genital CSA and especially intercourse, where most ORs exceeded 3.0. A similar pattern of findings was seen with CSA as reported by the cotwin, although many ORs were smaller. Controlling for family background factors and parental psychopathology produced a small to modest reduction in ORs. In twin pairs discordant for CSA, the exposed twin was at consistently higher risk of illness.

CONCLUSIONS

Women with CSA have a substantially increased risk for developing a wide range of psychopathology. Most of this association is due to more severe forms of CSA and cannot be explained by background familial factors. Although other biases cannot be ruled out, these results are consistent with the hypothesis that CSA is causally related to an increased risk for psychiatric and substance abuse disorders.

College women's awareness and consumption of folic acid for the prevention of neural tube defects

PURPOSE

Awareness and consumption of folic acid in the context of neural tube defect prevention among college women were assessed.

METHODS

Subjects documented folic acid awareness and multivitamin consumption. Beliefs about folic acid before and after an educational intervention were characterized using the Health Belief Model (HBM) and the Fetal Health Locus of Control Scale (FHLCS).

RESULTS

Awareness of folic acid was not associated with multivitamin consumption. Belief variables were not associated with awareness or consumption of folic acid.

CONCLUSION

This study does not support educational interventions based on the HBM or FHLCS to increase multivitamin consumption among college women.

IntroductionExposing Misinformation Concerning Child Sexual Abuse and Adult Survivors

This article introduces a special volume on misinformation about child sexual abuse. Despite extensive research findings on the long-term effects and consequences of child sexual abuse, misinformation on this topic is widespread. Several forces have worked to support and disseminate this erroneous information. Because it is difficult to comprehend the horror of sexual crimes against children, society's denial and disbelief have often unwittingly supported the agendas of those who want to discount or minimize the impact of these crimes. The media has also contributed to the aura of skepticism surrounding claims of sexual abuse and its mental health impact, and has reported favorably on controversial and unproven claims such as the &#0147;false memory syndrome.&#0148; In the hope of countering misinformation and thus raising the level of discourse to the engagement of real scientific issues, a number of well known and respected researchers and clinicians examine various facets of the problem.

An evaluation of different approaches for behavior genetic analyses with psychiatric symptom scores

We used a simulation study to evaluate six approaches for behavior genetic analyses of psychiatric symptom scores. For the selection of the correct model, the best results were obtained with approaches using transformed scores in combination with a procedure involving p-values. With normalizing transformations, the chi 2 test statistic gave a reasonable impression of the overall fit of the model but was less accurate when used as a difference test. The asymptotic distribution free estimation methods yielded chi 2s that were much too large. All data analysis techniques yielded substantially biased parameter estimates. The most biased results were obtained with normalizing transformations. The least biased results were obtained with tobit correlations, but because of its large standard errors the most precise estimates were obtained with polychoric correlations and optimal scale scores. An empirical study showed that a recognition of the role of methodological factors was helpful to understand part of the differences between assessment instruments, raters, and data analysis techniques that were found in the real data.

The influence of genetic factors and life stress on depression among adolescent girls

BACKGROUND

The possible causes of greater depression among adolescent girls were investigated by examining variation in the influence of genetic and environmental risk factors among 182 prepubertal female, 237 prepubertal male, 314 pubertal female, and 171 pubertal male twin pairs from the Virginia Twin Study of Adolescent Behavioral Development.

OBJECTIVES

To compare the trajectory of depressive symptoms among boys and girls from childhood to adolescence; to analyze the role of genetic, shared, and unique environmental factors in depression among prepubertal and pubertal male and female twins; and to investigate a possible link between liability to depression and one salient index of the child's environment: past-year life events.

METHODS

Child-reported depression was assessed using the Child and Adolescent Psychiatric Interview and ratings of past-year life events and pubertal status obtained by maternal questionnaire and interview, respectively.

RESULTS

The impact of life events on depression was particularly evident in the adolescent girls. The results from model fitting indicate increased heritability for depression in this group, and its long-term consistency was mediated primarily by latent genetic factors. Model fitting also showed that at least part of the liability to depression and to life events can be linked to a common set of genes in the adolescent girls, and there is a notable developmental increase in the genetic variance for life events.

CONCLUSIONS

The greater heritability for depression in pubertal girls, its genetic mediation over time, and the increase in genetic variance for life events may be one possible explanation for the emergence of increased depression among pubertal girls and its persistence through adolescence.

Genetics and child psychiatry: II Empirical research findings

Key substantive findings from quantitative and molecular genetic research are reviewed in relation to affective disorder, schizophrenia, autism, hyperkinetic/attention deficit disorder, oppositional and conduct disorders, drug/alcohol problems, and Tourette's syndrome/chronic tics.

Genetics and child psychiatry: I Advances in quantitative and molecular genetics

Advances in quantitative psychiatric genetics as a whole are reviewed with respect to conceptual and methodological issues in relation to statistical model fitting, new genetic designs, twin and adoptee studies, definition of the phenotype, pervasiveness of genetic influences, pervasiveness of environmental influences, shared and nonshared environmental effects, and nature-nurture interplay. Advances in molecular genetics are discussed in relation to the shifts in research strategies to investigate multifactorial disorders (affected relative linkage designs, association strategies, and quantitative trait loci studies); new techniques and identified genetic mechanisms (expansion of trinucleotide repeats, genomic imprinting, mitochondrial DNA, fluorescent in-situ hybridisation, behavioural phenotypes, and animal models); and the successful localisation of genes.

Genetic and environmental influences on subtypes of conduct disorder behavior in boys

Oppositional and conduct disorders are a heterogeneous collection of disruptive behaviors associated with diverse risk factors and varying outcomes. Data from males in the Virginia Twin Study of Adolescent Behavioral Development (VTSABD) are used to explore the relative importance of genetic and environmental influences on four previously described disruptive subtypes: property violations, status violations, oppositional behavior, and aggression. Striking differences between results according to mother and child ratings are found, indicating the need to consider carefully the origin of rater differences. Child ratings indicate support for a general genetic liability, with greatest influence on property violations, oppositional behavior and aggression. Maternal ratings suggest that the genetic factors influencing conduct disorder behavior are more specific to the behavioral area, with the stronger genetic influence on property violations and aggression.

Genetic "clocks" and "soft" events: a twin model for pubertal development and other recalled sequences of developmental milestones, transitions, or ages at onset

We propose and explore a twin model to examine the basis for synchrony that often characterizes different facets of normal development. In so doing we also present an approach to the analysis of "soft" events; events for which available reports of dates or ages of occurrence are unreliable or inconsistent. Discrepancies among reports are accounted for by a statistical measurement model. This combines current status error reflecting uncertain definition of onset and two mechanisms for the phenomenon of "telescoping," namely, systematic compression of the time scale and heteroscedastic random measurement error. Statistically, the model can be viewed as a mixed generalized linear model with random effects within both mean and variance functions or, alternatively, as involving multiplicative random effects. We apply the model to multiple maternal reports on menarche and onset of breast development in twin daughters. Fitted to data from the Virginia Twin Study Of Adolescent and Behavioral Development by the use of penalized/predictive quasi-likelihood, the model provided much improved estimates of the true age-at-onset distribution as compared to those from a naive analysis. Results suggested that the observed variance was made up almost entirely of genetic variance and measurement error variance due to telescoping and current status errors and that the timing of breast development and menarche are largely under the control of a common set of genes. Results also indicated that maternal recollections of the onset of breast development were both more poorly defined and subject to greater recall errors than maternal recollections of menarche.

Age changes in the causes of individual differences in conservatism

Age-related changes are analyzed in the correlation of 3416 monozygotic and 3780 dizygotic U.S. twin pairs aged between 9 and 75+ years for conservatism scores derived from a 28-item social attitude inventory. The effects of the shared environment are overwhelming in twins aged 20 years or younger. In older twins, genetic effects appear to play a larger role. A more dynamic conception of the interaction between genes and environment in the development of complex human differences is needed.

Genetic and environmental influences on the covariation between hyperactivity and conduct disturbance in juvenile twins

Structural equation models were applied to the maternal ratings of 265 MZ and 163 DZ male-male, 347 MZ and 160 DZ female-female, and 262 male-female twin pairs, aged 8-16 years, who participated in the Virginia Twin Study of Adolescent Behavioral Development (VTSABD). Substantial additive genetic influences and contrast effects were found for hyperactivity, and additive genetic and shared environmental effects or positive comparison effects (particularly for the girls) for oppositional/ conduct disturbance. Bivariate model fitting showed that the covariation between hyperactivity and oppositional/conduct problems in both younger and older boys and girls is almost entirely attributable to genetic factors. However, whereas in the younger males and females the same set of genes explain all the variation in hyperactivity and conduct disturbance, in the older cohort at least some of the genetic effects are behavior- and gender-specific.

Differences in the refractory properties of two distinct inhibitory circuitries in field CA1 of the hippocampus

Extracellular reflections of IPSPs were examined in two distinct circuitries in field CA1 of the hippocampus. Stimulation in the stratum radiatum in the presence of AMPA receptor antagonists elicited positive potentials in the same stratum that were eliminated by picrotoxin, a blocker of GABAA receptors. Laminar profile analysis revealed that the response was maximal in the stratum radiatum at a point well distal to the pyramidal cell body layer and had a negative reflection in the stratum oriens. These field IPSPs presumably mediate the feedforward inhibition normally activated by the Schaffer-commissural projections to field CA1. Stimulation of the alveus produced an antidromic response followed by a much slower positive potential in recordings collected in the pyramidal cell layer. The latter response was suppressed by AMPA receptor antagonists or picrotoxin, as expected for disynaptic, recurrent (feedback) inhibition. The laminar profile for the feedback field IPSPs had its maximum near the pyramidal cell layer and its negative dipole in the stratum radiatum. Feedforward IPSPs were inhibited by about 50% if they were preceded within 200 ms by a priming pulse while feedback IPSPs were reduced by less than 20% under comparable conditions. The refractory effect was minimally dependent on stimulation intensity but was strongly affected by an antagonist of GABAB receptors. Attempts to modify IPSPs in the s. radiatum with long trains of low frequency stimulation or with theta-burst stimulation were not successful, suggesting that GABAergic synapses do not have the plasticities found in their glutamatergic counterparts. These results indicate that interneurons contacted by the extrinsic afferents of hippocampus form GABAergic synapses that differ in terms of spatial location and functional properties from the synapses generated by interneurons innervated by the recurrent collaterals of the pyramidal cells. The findings also suggest that repetitive afferent activity, while reducing the influence of dendritic IPSPs on excitatory input, will leave feedback suppression of cell spiking largely intact.

Multiple raters of disruptive child behavior: using a genetic strategy to examine shared views and bias

Most research on child behavior incorporates information from different individuals. While agreement between informants is generally only modest, there is little understanding of the processes underlying disagreement. In twin studies, differential agreement among raters for MZ and DZ twins is of particular concern. The processes underlying differences among mother, father, and child ratings of oppositional and conduct disorder symptoms are explored. Evidence in favor of a shared parental view of behavior is presented. Parental ratings give higher intrapair correlations, which could be due to either parents rating their twins more similarly or twins contrasting themselves. Rater bias and situational specificity are among the possible explanations of differential ratings. The effects of incorporating multiple raters of behavior on estimates of genetic and environmental effects are explored. These suggest that genetic influences are greater for the shared (multiple-rater) phenotype than for individual ratings; reduction in measurement error is only a partial explanation.

Effect of thiocyanate on AMPA receptor mediated responses in excised patches and hippocampal slices

The binding affinity of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors for [3H]AMPA is increased 10-30-fold by the chaotropic anion thiocyanate. The present experiments tested if thiocyanate alters AMPA receptor mediated current fluxes and if any such effects are reflected in the waveform of synaptic responses. Currents were measured after a step application of glutamate or AMPA to patches excised from pyramidal cells of hippocampal slice cultures. Application of 1 mM AMPA produced responses with an average peak amplitude of 86 pA at -50 mV and a 10-90% rise time of 1.7 +/- 0.1 ms; the responses desensitized to a steady-state level below 10% of the peak current with a time constant of 11.1 +/- 0.7 ms. Glutamate in presence of D-amino-phosphonopentanoate produced similar responses which were inhibited by 6-cyano-7-nitro-quinoxaline-dione and enhanced by aniracetam or cyclothiazide and thus are characteristic for AMPA receptors. Thiocyanate accelerated the decay of AMPA responses two-fold and reduced the peak current by 30-50% with an EC50 of 3.2 mM which is comparable to its EC50 for enhancing binding. Effects on the desensitization of glutamate induced responses were much smaller and only evident at the highest thiocyanate concentration; no effect was seen on response amplitude. Binding and physiological effects can be adequately explained by assuming that thiocyanate enhances conversion from the sensitive to the desensitized state of the receptor and reduces ligand dissociation from the desensitized state. Synaptic responses were measured in disinhibited hippocampal slices. Perfusion with 20 mM sodium thiocyanate increased the slope of the field excitatory postsynaptic potential by 44.9 +/- 4.2% and reduced its decay time by 10.4 +/- 4.3%. The former effect appears to result at least in part from an increase in transmitter release since it was accompanied by a decrease in paired-pulse facilitation and was reduced in magnitude after enhancing transmitter release. The decrease in the decay time constant points to an effect of thiocyanate on AMPA receptors in situ which is similar to that seen in excised patches. These results demonstrate that an increase in binding affinity may be indicative of reduced rather than enhanced current flow through AMPA receptors. In addition, the results provide further evidence that the kinetics of the AMPA receptor channel contribute significantly to at least the decay phase of fast excitatory synaptic responses.

A simple method for censored age-of-onset data subject to recall bias: mothers' reports of age of puberty in male twins

Genetic analysis of variation in age of onset of development milestones or psychopathological behaviors has been little researched, owing largely to the computational difficulty of dealing with "censored" observations. Censored observations arise when the only information on individuals is that they have reached a particular age but without onset having occurred. This paper shows how models can be simply fitted to such data using programs that can perform genetic analysis of categorical data by maximum likelihood. The method is illustrated using the program Mx with data on maternal report of the onset of puberty in twin sons from the Virginia Twin Study of Adolescent Behavioral Development. Frequently, data on age of onset is collected by retrospective recall. This can pose a variety of measurement problems. Suggestions are made for models that account for some of these problems or are robust to their presence. Substantial evidence for "telescoping" of onset dates is found for the puberty data. If left unaccounted for, these effects can artifactually inflate estimates of common environment effects.

Survival models for developmental genetic data: age of onset of puberty and antisocial behavior in twins

The use of survival analysis for developmental genetic data is discussed. The main requirements for models based on the decomposition of frailty distributions into shared and unshared components are outlined for the simple case of twins. Extending the earlier work of Clayton, Oakes, and Hougaard, among others, three forms of hazard model are presented, all of which can be applied to pedigree data with flexible baseline hazards without the use of numerical integration. The first two models use an additive decomposition of frailty, with either gamma or positive stable law distributed (PSL) components. The third model previously described by Hougaard involves a multiplicative PSL decomposition. The models are applied to data on the onset of puberty in male twins and illustrate the importance of correct specification of the baseline hazard for correct inference about genetic effects. The difficulty of assessing model specification using information only on the margins is also noted. Overall, the new model with additive PSL components appeared to fit these data best. A second application illustrates the use of a time-varying covariate in examining the impact of puberty on the onset of conduct disorder symptomotology.

A model system for analysis of family resemblance in extended kinships of twins

The "Virginia 30,000" comprise 29,698 subjects from the extended kinships of 5670 twin pairs. Over 80 unique correlations between relatives can be derived from these kinships, comprised of monozygotic (MZ) and dizygotic (DZ) twins and their spouses, parents, siblings, and children. This paper describes the first application of a fairly general model for family resemblance to data from the Virginia 30,000. The model assesses the contributions of additive and dominant genetic effects in the presence of vertical cultural inheritance, phenotypic assortative mating, shared twin and sibling environments, and within-family environment. The genetic and environmental effects can be dependent on sex. Assortment and cultural inheritance may be based either on the phenotype as measured or on a latent trait of which the measured phenotype is an unreliable index. The model was applied to church attendance data from this study. The results show that the contributions of genes, vertical cultural inheritance, and genotype-environment covariance are all important, but their contributions are significantly heterogeneous over sexes. Phenotypic assortative mating has a major impact on family resemblance in church attendance.