A twin study of genetic influences on behavioral deviance

The Genetic Architecture of Neuroticism in 3301 Dutch Adolescent Twins as a Function of Age and Sex: A Study From the Dutch Twin Register

The objective of this study was to estimate the magnitude of genetic and environmental influences to variation in adolescent neuroticism as a function of age and sex. Neuroticism was assessed using the Amsterdamse Biografische Vragenlijst (ABV): a self-report personality instrument similar in content to the Eysenck Personality Questionnaire. Genetic modeling procedures, including age as modifier, were fitted to the total sample of 3301 Dutch adolescent twins aged 12 to 17 years (mean age 15.5). Significant influences of additive genetic factors (.59, 95% confidence intervals [CI] .54–.63) and unshared environmental factors (.41, 95% CI .37–.45) were found. Our data did not support a role of shared environment. Results showed that different genes may influence variation in neuroticism between girls and boys. No interaction was found between the variance components and age. Results generally support prior findings in adults and young children that neuroticism is influenced principally by additive genetic and unique environmental factors. The magnitude of the genetic component appears higher in the present sample of adolescents than in most studies of adults. The present study suggests that, in adolescence, different genes are expressed in boys and girls.

The nature of nurture: Genetic influence on “environmental” measures

Evidence for genetic influence on environmental measures will emerge in quantitative genetic analyses if genetically influenced characteristics of individuals are assessed by these environmental measures. Recent twin and adoption studies indicate substantial genetic influence when measures of the environment are treated as phenotypes in genetic analyses. Genetic influence has been documented for measures as diverse as videotaped observations of parental behavior toward their children, ratings by parents and children of their family environment, and ratings of peer groups, social support, and life events. Evidence for genetic influence on environmental measures includes some of the most widely used measures of environment – the Home Observation for Measurement of the Environment, the Family Environment Scales, and the Social Readjustment Rating Scale of life events, for example. The goal of this article is to document and discuss these findings and to elicit commentary that might help to shape the course of research on this topic, which has far-reaching implications for the behavioral and brain sciences.

Monoamine oxidase A and childhood adversity as risk factors for conduct disorder in females

BACKGROUND

Recent studies among males have reported a genotype-environment interaction (GxE) in which low-activity alleles at the monoamine oxidase A (MAOA) locus conferred greater sensitivity to the effects of childhood adversity on risk for conduct disorder (CD). So far, few studies of females have controlled for gene-environment correlation or used females heterozygous for this X-linked gene.

METHOD

Logistic regression analysis of a sample of 721 females ages 8-17 years from the longitudinal Virginia Twin Study of Adolescent Behavioral Development (VTSABD) assessed the additive effects of MAOA genotypes on risk for CD, together with the main effect of childhood adversity and parental antisocial personality disorder (ASP), as well as the interaction of MAOA with childhood adversity on risk for CD.

RESULTS

A significant main effect of genotype on risk for CD was detected, where low-activity MAOA imparted the greatest risk to CD in girls while controlling for the significant effects of maternal ASP and childhood adversity. Significant GxE with weak effect was detected when environmental exposure was untransformed, indicating a higher sensitivity to childhood adversity in the presence of the high-activity MAOA allele. The interaction was no longer statistically significant after applying a ridit transformation to reflect the sample sizes exposed at each level of childhood adversity.

CONCLUSIONS

The main effect of MAOA on risk for CD in females, its absence in males and directional difference of interaction is suggestive of genotype-sex interaction. As the effect of GxE on risk for CD was weak, its inclusion is not justified.

Behavior problems in 5-year-old monozygotic and dizygotic twins: Genetic and environmental influences, patterns of regulation, and internalization of control

Genetic influence on externalizing problems, internalizing problems, and attentional/activity problems in 5-year-olds was consistently identified across informants and assessment contexts. Effects of the shared environment were identified as well but with less consistency (i.e., only from parents, not teachers, and more from father than mother reports). Correlations between observed patterns of regulation at ages 3, 4, and 5 years and behavior problems at age 5 years were often significant, but low in magnitude and specific to teacher reports. Adaptive internalization of control at each age (e.g., frustration tolerance, capacity to attend and focus, good impulse control) predicted fewer externalizing problems. Internalization of standards, reflected in children's moral themes, understanding of reciprocity, and constructive social problem solving, also were sometimes associated with fewer problems. Significant correlations were low in magnitude and again specific to teacher reports. Externalizing problems were more prevalent for boys than girls, and regulation (i.e., internalization of control and standards) was more characteristic of girls than boys.

The genetic architecture of neuroticism in 3301 Dutch adolescent twins as a function of age and sex: a study from the Dutch twin register

The objective of this study was to estimate the magnitude of genetic and environmental influences to variation in adolescent neuroticism as a function of age and sex. Neuroticism was assessed using the Amsterdamse Biografische Vragenlijst (ABV): a self-report personality instrument similar in content to the Eysenck Personality Questionnaire. Genetic modeling procedures, including age as modifier, were fitted to the total sample of 3301 Dutch adolescent twins aged 12 to 17 years (mean age 15.5). Significant influences of additive genetic factors (.59, 95% confidence intervals [CI] .54-.63) and unshared environmental factors (.41, 95% CI .37-.45) were found. Our data did not support a role of shared environment. Results showed that different genes may influence variation in neuroticism between girls and boys. No interaction was found between the variance components and age. Results generally support prior findings in adults and young children that neuroticism is influenced principally by additive genetic and unique environmental factors. The magnitude of the genetic component appears higher in the present sample of adolescents than in most studies of adults. The present study suggests that, in adolescence, different genes are expressed in boys and girls.

Genetics and developmental psychopathology: 2. The main effects of genes and environment on behavioral problems in the Virginia Twin Study of Adolescent Behavioral Development

Little is known about the contribution of genetic and environmental factors to risk for juvenile psychopathology. The Virginia Twin Study of Adolescent Behavioral Development allows these contributions to be estimated. A population-based, unselected sample of 1412 Caucasian twin pairs aged 8-16 years was ascertained through Virginia schools. Assessment of the children involved semi-structured face-to-face interviews with both twins and both parents using the Child and Adolescent Psychiatric Assessment (CAPA). Self-report questionnaires were also completed by parents, children, and teachers. Measures assessed DSM-III-R symptoms of Attention Deficit Hyperactivity Disorder (ADHD). Conduct Disorder, Oppositional Defiant Disorder, Overanxious Disorder, Separation Anxiety, and Depressive Disorder. Factorially derived questionnaire scales were also extracted. Scores were normalized and standardized by age and sex. Maximum likelihood methods were used to estimate contributions of additive and nonadditive genetic effects, the shared and unique environment, and sibling imitation or contrast effects. Estimates were tested for heterogeneity over sexes. Generally, monozygotic (MZ) twins correlated more highly than dizygotic (DZ) twins, parental ratings more than child ratings, and questionnaire scales more highly than interviews. DZ correlations were very low for measures of ADHD and DZ variances were greater than MZ variances for these variables. Correlations sometimes differed between sexes but those for boy-girl pairs were usually similar to those for like-sex pairs. Most of the measures showed small to moderate additive genetic effects and moderate to large effects of the unique individual environment. Measures of ADHD and related constructs showed marked sibling contrast effects. Some measures of oppositional behavior and conduct disorder showed shared environmental effects. There were marked sex differences in the genetic contribution to separation anxiety, otherwise similar genetic effects appear to be expressed in boys and girls. Effects of rater biases on the genetic analysis are considered. The study supports a widespread influence of genetic factors on risk to adolescent psychopathology and suggests that the contribution of different types of social influence may vary consistently across domains of measurement.

Genetics and developmental psychopathology: 1. Phenotypic assessment in the Virginia Twin Study of Adolescent Behavioral Development

We introduce an overlapping cohort sequential longitudinal study of behavioral development and psychopathology in a representative sample of 1412 pairs of twins aged 8 through 16 years. Multiple phenotypic assessments involve a full psychiatric interview with each child and each parent, and supplementary parental, teacher, and child interview material and questionnaires. For the first wave of assessments, the numbers of reported DSM-III-R symptoms of Major Depressive Disorder (MDD), Separation Anxiety Disorder (SAD), Overanxious Disorder (OAD), Oppositional Defiant Disorder (ODD), Conduct Disorder (CD), and Attention Deficit Hyperactivity Disorder (ADHD), assessed through interviews, confirm patterns of age and sex trends found in other epidemiological samples, but underscore their dependence on whether the child or the parent is the informant. Correlations across domains for symptoms reported by the same informant are often as large as correlations across informants for the same domain of symptoms. Factor analyses of these symptom counts, taking account of informant view and unreliability of assessment, show the high degree of correlation between SAD and OAD, between MDD and OAD, and between CD and ODD. ADHD symptoms are relatively independent of the other domains, but show moderate correlations with CD, ODD, and MDD. Factorially derived dimensional questionnaire scales, based on child, parental, and teacher reports, show patterns of relationship to symptom counts consistent with both convergent and discriminant validity as indices of liability to clinical symptoms. Across informants, questionnaire scales provide as good a prediction of symptoms as do clinical interviews. Multitrait-multimethod confirmatory factor analysis reveals the patterns of relationship between symptoms of psychiatric disorder in children taking due account of informant and unique sources of variance. Gender differences are consistent within the correlated clusters of ODD/CD and MDD/SAD/OAD, although there are disorder-specific age trends. There are large informant-specific influences on the reporting of symptoms in clinical interviews. Dimensional questionnaire scales provide a useful source of additional information. In subsequent analyses of genetic and environmental etiology of childhood psychopathology we must expect that results may differ by informant and method of assessment. Multivariate and developmental analyses that explore the sources of these differences will shed new light on the relationship between genetic and environmentally influenced vulnerability and the manifestation of psychopathology in specific circumstances.

Does psychiatric history bias mothers' reports? An application of a new analytic approach

OBJECTIVE

To evaluate whether mothers' psychiatric history biases reports of their children's behavior problems, mothers' and teachers' reports of children's behavior problems were compared using a recently developed statistical approach.

METHOD

Child Behavior Checklists and Teacher's Report Forms were completed by mothers and teachers, respectively, about 801 six-year-old children. Mother's history of major depression, anxiety disorders, and substance use disorder was assessed by using the National Institute of Mental Health Diagnostic Interview Schedule. Generalized estimating equations were used for data analysis.

RESULTS

According to both teachers and mothers, maternal history of major depression was associated with more internalizing problems; the association was significantly stronger when mothers were the informants. Mothers with history of any psychiatric disorder reported more externalizing problems in their children than expected, whereas teachers' reports of externalizing behaviors were unrelated to maternal psychiatric history. These findings could not be explained by variations in children's behaviors across settings.

CONCLUSION

The generalized estimating equation models enabled simultaneous examination of whether children of depressed mothers have excess behavior problems and whether depressed mothers overreport behavior problems in their children. The results indicate that children of depressed mothers have more internalizing problems. In addition, depressed mothers overstate and overgeneralize their offspring's behavior problems. This study broadens the concerns with reporting bias beyond maternal depression to include other psychiatric problems. The results emphasize the potential for bias in family history studies that rely on informants.

Behavioural problems of children with chronic physical illness and their siblings

Children suffering from chronic physical illness are considered to be at increased risk for behavioural problems. There is also evidence that their siblings are at risk for behavioural problems. This study investigated parent-reported behavioural problems in chronically ill children and their siblings. There were significant positive correlations between the behaviour problem scores of the ill children and the scores of their siblings. Siblings older than the ill child had significantly higher behaviour problems scores of an internalizing nature than did the younger siblings. Sibling behaviour problem scores were similar to those of a comparison group of normal children and significantly different from those of a comparison group of psychiatrically referred children. Siblings of chronically ill children showed no greater likelihood of receiving scores in the clinical range of behaviour problems than children in the general population. Implications of the findings and suggestions for future research are discussed.

A new instrument to assess sibling relationships in antisocial youth: the social interaction between siblings (SIBS) interview: a research note

This paper presents psychometric information on a new interview (SIBS) designed to examine sibling influences on antisocial behavior. The feasibility of the instrument and internal consistency of the SIBS scales was documented in a sample of 29 children (ages 6-11) with a delinquent older brother. In addition, adequate to excellent test-retest reliability of the SIBS scales was demonstrated in an unselected sample. The potential utility of the SIBS interview for assessing the role of siblings in the development of antisocial behavior is discussed.

A twin study of antisocial and neurotic symptoms in childhood

There is some evidence to suggest that the role of genetic and environmental influences may vary for different types of psychiatric symptoms in childhood. The aim of this study was to examine to what extent genetic and environmental factors influence parent-rated conduct and neurotic symptoms in childhood and adolescence, using data obtained from a systematically ascertained sample of twins (198 same sex pairs) aged between 8 and 16 years. For symptoms of antisocial behaviour, transmission could be explained entirely by shared environmental factors. Social class effects were also found to have a significant influence on antisocial behaviour, although these effects only accounted for a small proportion of the variance explained by shared environmental factors. In contrast, transmission of neurotic symptoms was best explained by additive genetic influences alone with no contribution from shared environment. Non-shared environmental factors accounted for a substantial component of the variation for both antisocial behaviour and neurotic symptoms.

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.

The impact of child IQ, parent IQ and sibling IQ on child behavioural deviance scores

In an epidemiological sample of 411 13-year-old twins of normal intelligence, both parents and teachers reported more behavioural problems among children with lower IQs. This was not attributable to the effects of parental IQ or social class and was not entirely mediated by lower scholastic attainments. Different causal models are discussed: "rater bias" and "IQ is a consequence" explanations seem less plausible than "IQ is a cause" and "IQ is a marker" explanations. Higher parental IQ was associated with more emotional symptoms in the child, both by parental and school report. There was no evidence that being brighter or less bright than a (twin) sibling influenced behavioural deviance, casting doubt on the importance of contrast effects.

The effect of maternal depression on maternal ratings of child behavior

There have been continuing concerns about the extent to which maternal depression may influence maternal reports of child behavior. To examine this issue, a series of structural equation models of the relationships between maternal depression and errors in maternal reports of child behavior was proposed and tested. These models assumed that (a) maternal depression was unrelated to maternal reporting behavior; (b) maternal depression causally influenced maternal reporting accuracy; (c) maternal depression was correlated with reporting accuracy. These models were fitted to data on maternal depression and multiple-informant (mother, teacher, child) reports of conduct disorder and attention deficit behaviors for a birth cohort of 12- and 13-year-old New Zealand children. The results of model fitting suggested the presence of small to moderate correlations (r = +.13 to +.40) between maternal depression and maternal reporting errors, indicating the presence of a tendency for increasing maternal depression to be associated with a tendency for mothers to over-report child behavior problems. However, independently of any effects of maternal depression on maternal reporting errors there was evidence of small but significant associations (r = .10 to .17; p < .05) between maternal depression and child conduct disorder and attention deficit behaviors.

The effect of maternal depression on maternal ratings of child behavior

There have been continuing concerns about the extent to which maternal depression may influence maternal reports of child behavior. To examine this issue, a series of structural equation models of the relationships between maternal depression and errors in maternal reports of child behavior was proposed and tested. These models assumed that (a) maternal depression was unrelated to maternal reporting behavior; (b) maternal depression causally influenced maternal reporting accuracy; (c) maternal depression was correlated with reporting accuracy. These models were fitted to data on maternal depression and multiple-informant (mother, teacher, child) reports of conduct disorder and attention deficit behaviors for a birth cohort of 12- and 13-year-old New Zealand children. The results of model fitting suggested the presence of small to moderate correlations (r = +.13 to +.40) between maternal depression and maternal reporting errors, indicating the presence of a tendency for increasing maternal depression to be associated with a tendency for mothers to over-report child behavior problems. However, independently of any effects of maternal depression on maternal reporting errors there was evidence of small but significant associations (r = .10 to .17; p < .05) between maternal depression and child conduct disorder and attention deficit behaviors.

Evidence for a genetic etiology in hyperactivity in children

There has been considerable controversy over the nosology of hyperactivity and attention deficit hyperactivity disorder (ADHD). There have been suggestions that genetic influences may play a role in the origins of individual differences on this dimension or dimensions of behavior and that an understanding of the significance of genetic factors might help to clarify the classification of these disorders. Multiple regression is used to analyze data from a sample of 91 pairs of identical twins and 105 pairs of same sex fraternal twins. The heritability of extreme group membership (h2g = 0.75) was significant for activity rated by the mother. The heritability for one of the measures of attention deficit was also significant (h2g = 0.76). The results are consistent with a significant genetic contribution to individual differences in activity levels and attention abilities.

The analysis of parental ratings of children's behavior using LISREL

A common procedure for assessing children's behavior is to obtain parental ratings of the child. Since the ratings obtained are a function of both parent and child, disentangling the child's phenotype from that of the rater becomes an important methodological problem. For the analysis of genetic and environmental contributions to children's behavior, solutions to this are available when multiple raters, e.g., two parents, rate multiple children, e.g., twins. This paper describes and illustrates simple LISREL models for the analysis of parental ratings of children's behavior. We show how the assumption that mothers and fathers are rating the same behavior in children can be contrasted with the weaker alternative that parents are rating correlated behaviors. Given the stronger assumption, which appears adequate for ratings of children's internalizing behavior problems, the contribution of rater bias and unreliability may be separated from the shared and nonshared environmental components of variation in a behavior genetic analysis.

Childhood behavior problems: a comparison of twin and non-twin samples

This study compares standardized measures of childhood behavior problems in a community-based twin sample with those for normative samples from the general population. Maternal parent ratings on the Child Behavior Checklist (CBCL) for 1824 twins were compared with the CBCL normative sample. The results indicated that twins showed small but consistently higher levels of problem behaviors. These elevations were significant for older children on both internalizing and externalizing behaviors; for younger children the elevations were significant for externalizing but not internalizing behaviors.