Genetic and environmental influences on child reports of manifest anxiety and symptoms of separation anxiety and overanxious disorders: a community-based twin study

Genetic and environmental sources of familial resemblance in anxiety: a nuclear twin family design

BACKGROUND

A dominant feature of anxiety disorders is familial aggregation. However, the underlying mechanisms of between- and within-generational anxiety resemblance remain poorly understood. By disentangling the genetic v. environmental sources of familial resemblance in anxiety, we can help prevent within-family transmission of anxiety disorders. Therefore, data from both parents and twins are needed to obtain unbiased and detailed estimations of genetic and environmental sources of similarity between family members.

METHODS

We examined data from 991 families with same-sex twins. Trait anxiety in twins was assessed via self-report and parent report, while parental trait anxiety was assessed via self-report. We established a nuclear twin family model and estimated genetic and environmental variances using two survey waves.

RESULTS

The results suggested that additive genetic (A), dominant genetic (D), and non-shared environmental (E) influences significantly contributed to trait anxiety, whereas familial environmental influences (F) and passive gene-environment correlations (rGE) did not. Sibling environmental influences (S) were only found in self-report data, and increased when genetic influences decreased from Wave 1 to Wave 2.

CONCLUSIONS

Our study highlights the important role of broad heritability in intrafamilial trait anxiety similarity. Parent-child resemblance occurred primarily due to shared genetic makeup rather than direct environmental transmission. Sibling-specific environments, as the only source of shared environments, need further investigation. These findings have both theoretical and practical significance for anxiety disorders. Future research can expand our understanding by examining the gene-environment interplay and sex differences.

The Differential Heritability of Social Adjustment by Sex

Sex differences in social adjustment are frequently observed; however, there has been very little research on adaptability in the individual and social domains. The aim of this study was to investigate the sex difference in social abilities, such as high self-appeal, sociability, school adaptation, and home adaptation between school-age males and females. The sample for this study included both same-sex and opposite-sex twin pairs: a total of 467 twin pairs. We classified them into three groups: a group of those in lower classes of elementary school, a group of those in higher classes of elementary school, and a group of those in junior high school. The heritability of school adaptation was estimated to be 95% in males and 54% in females in the junior high school group. The full sex-limitation model showed a better fit in this group, and this means that a qualitative genetic difference exists. For school adaptation, there was no sex difference in lower elementary school classes; however, a quantitative difference appeared in higher classes of elementary school. Moreover, a qualitative difference appeared in junior high school. From this research, it became clear that sex differences in heritability exist for school adaptation, and there was a marked increase from the elementary school children to the junior high school children.

Genetic and environmental influences on internalizing psychopathology across age and pubertal development

Symptoms of anxiety and depression are commonly comorbid and partially share a genetic etiology. Mean levels of anxiety and depression increase over the transition to adolescence, particularly in girls, suggesting a possible role of pubertal development in the activation of underlying genetic risks. The current study examined how genetic and environmental influences on anxiety and depression differed by chronological age and pubertal status. We analyzed composite scores from child self-reports and parent informant-reports of internalizing symptomology in a racially and socioeconomically diverse sample of 1,913 individual twins from 1,006 pairs (ages 8-20 years) from the Texas Twin Project. Biometric models tested age and pubertal status as moderators of genetic and environmental influences shared between and specific to anxiety and depression to determine whether etiology of internalizing symptomology differs across development as a function of age or puberty. Genetic influences did not increase as a function of age or puberty, but instead shared environmental effects decreased with age. In an exploratory model that considered the moderators simultaneously, developmental differences in etiology were reflected in genetic and environmental effects unique to depression. Results suggest that genetic variance in internalizing problems is relatively constant during adolescence, with environmental influences more varied across development. (PsycINFO Database Record

Environmental transmission of generalized anxiety disorder from parents to children: worries, experiential avoidance, and intolerance of uncertainty

Generalized anxiety disorder (GAD) runs in families. Building on recent theoretical approaches, this review focuses on potential environmental pathways for parent-to-child transmission of GAD. First, we address child acquisition of a generalized pattern of fearful/anxious and avoidant responding to potential threat from parents via verbal information and via modeling. Next, we address how parenting behaviors may contribute to maintenance of fearful/anxious and avoidant reactions in children. Finally, we consider intergenerational transmission of worries as a way of coping with experiential avoidance of strong negative emotions and with intolerance of uncertainty. We conclude that parents with GAD may bias their children's processing of potential threats in the environment by conveying the message that the world is not safe, that uncertainty is intolerable, that strong emotions should be avoided, and that worry helps to cope with uncertainty, thereby transmitting cognitive styles that characterize GAD. Our review highlights the need for research on specific pathways for parent-to-child transmission of GAD.

The Shared Etiology of Attentional Control and Anxiety: An Adolescent Twin Study

We investigated the etiology of attentional control (AC) and four different anxiety symptom types (generalized, obsessive-compulsive, separation, and social) in an adolescent sample of over 400 twin pairs. Genetic factors contributed to 55% of the variance in AC and between 43 and 58% of the variance in anxiety. Negative phenotypic associations between AC and anxiety indicated that lower attentional ability is related to increased risk for all 4 anxiety categories. Genetic correlations between AC and anxiety phenotypes ranged from -.36 to -.47, with evidence of nonshared environmental covariance between AC and generalized and separation anxiety. Results suggest that AC is a phenotypic and genetic risk factor for anxiety in early adolescence, with somewhat differing levels of risk depending on symptomatology.

Developmental changes in genetic and environmental influences on Chinese child and adolescent anxiety and depression

BACKGROUND

Twin and family studies using Western samples have established that child and adolescent anxiety and depression are under substantial genetic, modest shared environmental, and substantial non-shared environmental influences. Generalizability of these findings to non-Western societies remains largely unknown, particularly regarding the changes of genetic and environmental influences with age. The current study examined changes in genetic and environmental influences on self-reported anxiety and depression from late childhood to mid-adolescence among a Chinese twin sample. Sex differences were also examined.

METHOD

Self-reported anxiety and depression were collected from 712 10- to 12-year-old Chinese twins (mean = 10.88 years, 49% males) and again 3 years later. Quantitative genetic modeling was used to examine developmental changes in genetic and environmental influences on anxiety and depression, and sex differences.

RESULTS

Heritability of anxiety and depression in late childhood (23 and 20%) decreased to negligible in mid-adolescence, while shared environmental influences increased (20 and 27% to 57 and 60%). Shared environmental factors explained most of the continuity of anxiety and depression (75 and 77%). Non-shared environmental factors were largely time-specific. No sex differences were observed.

CONCLUSIONS

Shared environmental influences might be more pronounced during the transition period of adolescence in non-Western societies such as China. Future research should examine similarities and differences in the genetic and environmental etiologies of child and adolescent internalizing and other psychopathology in development between Western and non-Western societies.

The pathogenesis of childhood anxiety disorders: Considerations from a developmental psychopathology perspective

Anxiety disorders are among the most prevalent psychiatric problems in children and adolescents. The present article summarizes the main evidence that has accumulated on the pathogenesis of childhood anxiety disorders during the past two decades. Various risk and vulnerability factors (e.g., genetics, behavioral inhibition, disgust sensitivity, negative life events, family influences), protective factors (e.g., effortful control, perceived control), and maintaining factors (e.g., avoidance, cognitive biases) will be discussed. The information will be described in terms of a developmental psychopathology perspective, which assumes that (a) most forms of psychopathology are the result of multiple causal influences; (b) both successful and unsuccessful adaptation are important for understanding the origins of psychopathology; and (c) psychopathology occurs in a developing organism.

Genetic and environmental contributions to anxiety among Chinese children and adolescents--a multi-informant twin study

BACKGROUND

Child and adolescent anxiety has become a major public health concern in China, but little was known about the etiology of anxiety in Chinese children and adolescents. The present study aimed to investigate genetic and environmental influences on trait anxiety among Chinese children and adolescents. Rater, sex, and age differences on these estimates were also examined.

METHODS

Self-reported and parent-reported child's trait anxiety was collected from 1,104 pairs of same-sex twins aged 9-18 years. Genetic models were fitted to data from each informant to determine the genetic (A), shared (C), and non-shared environmental (E) influences on trait anxiety.

RESULTS

The parameter estimates and 95% confidence intervals (CI) of A, C, E on self-reported trait anxiety were 50% [30%, 60%], 5% [0%, 24%], 45% [40%, 49%]. For parent-reported data, the corresponding parameter estimates were 63% [47%, 78%], 13% [1%, 28%], and 24% [22%, 27%], respectively. The heritability of anxiety was higher in girls for self-reported data, but higher in boys for parent-reported data. There was no significant age difference in genetic and environmental contributions for self-reported data, but a significant increase of heritability with age for parent-reported data.

CONCLUSIONS

The trait anxiety in Chinese children and adolescents was highly heritable. Non-shared environmental factors also played an important role. The estimates of genetic and environmental effects differed by rater, sex and age. Our findings largely suggest the cross-cultural generalizability of the etiological model of child and adolescent anxiety.

Are childhood trauma exposures predictive of anxiety sensitivity in school attending youth?

BACKGROUND

Stressful life events in adolescents have been found to be longitudinally associated with higher anxiety sensitivity (AS). A question that has not been addressed is whether AS in adolescence is associated with different childhood adversity exposures.

METHODS

School attending adolescents (n=1149) completed measures of anxiety sensitivity (CASI), trait anxiety (STAI-T), childhood trauma (CTQ), depression (CES-DC), alcohol (AUDIT) and drug use (DUDIT), and resilience (CD-RISC) and coping orientation (A-COPE).

RESULTS

There was no significant gender difference in childhood trauma exposure, resilience levels or coping orientation. Gender differences were evident in terms of AS, trait anxiety, depression, alcohol and drug use. Depression, trait anxiety and alcohol use mediated the relationship between the amount of childhood trauma and AS and played a role in the relationship between certain childhood trauma types and AS. Neither resilience nor coping orientation had a moderating effect on the relationship between the amount of childhood trauma and AS.

LIMITATIONS

Cross-sectional study, over- or under-reporting of data due to use of self-report instruments, and use of a retrospective measure of childhood trauma (CTQ) that is subject to recall bias.

CONCLUSIONS

Girls are at greater risk than boys for early onset anxiety disorders as girls have higher rates of AS, trait anxiety and depression despite the same rates of childhood trauma, coping orientation and resilience. Our findings, in the context of childhood trauma, underscore the influence of depression, trait anxiety and alcohol use as risk factors for the development of AS in youth.

Genetic and environmental causes of variation in adolescent anxiety symptoms: a multiple-rater twin study

Heritability estimates for adolescent anxiety vary across studies, partly depending on who is rating the symptoms. The goal of our study was to estimate genetic and environmental influences using a multi-informant design with responses from a population-based sample of adolescent twins, their mothers and their fathers (N=1394 families). Results from multivariate biometrical modeling indicated quantitative, but no qualitative sex differences in etiology. The best fitting model was an AE Common Pathway model, defining anxiety as a latent factor common to all informants. This model offers error free estimates of genetic and environmental influences explaining the latent factor variance. Variation in the latent factor was highly genetic, with heritability estimates of 65% for boys and 74% for girls. Non-shared environmental effects explained the remaining variance. In addition, there were significant rater-specific genetic and environmental effects for both sexes. The observed rater differences underline the importance of using several informants when studying adolescent anxiety.

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.

Beliefs regarding child anxiety and parenting competence in parents of children with separation anxiety disorder

BACKGROUND AND OBJECTIVES

Despite the fact that numerous developmental models have highlighted the role of parental cognitive processes in connection with anxiety disorders in children and adolescents, the role of parents' beliefs about their children and parenting remains largely unexplored. This study investigated the specific association between parental beliefs and child separation anxiety.

METHOD

Parents of children with a diagnosis of Separation Anxiety Disorder (SAD) reported on beliefs and expectations related to their child's fears and own parenting competence. To study the potential specificity of relationships, a clinical control group of mothers of children with social phobia (SoP) and a group of mothers of children without a mental disorder (healthy controls, HC) were included.

RESULTS

Results indicated that parents of anxious children had significantly higher levels of dysfunctional beliefs than the parents in the HC group. Mothers of children with SAD showed lower levels of parenting self-efficacy than mothers of children with SoP. They also demonstrated lower parenting self-efficacy and satisfaction compared to mothers of healthy children. Parental dysfunctional beliefs about child anxiety and paternal parenting self-efficacy were significantly positively associated with child anxiety. The effects remained significant after controlling for parental anxiety and depression.

LIMITATIONS

Due to the cross-sectional design of the study, causality of the found effects cannot be inferred.

DISCUSSION

Data suggest that children's anxiety and parents' beliefs about their child's anxiety, coping skills and parenting are strongly associated. Further research is needed to investigate whether addressing parental cognitions in addition to parents' anxiety may improve prevention and intervention of child anxiety.

Early stuttering, temperament and anxiety: two hypotheses

PURPOSE

The topic of temperament and early stuttering and the extent to which it involves anxiety is theoretically and clinically relevant. The topic can contribute to theory development and clinical practices with early stuttering.

METHOD

We present a review of the empirical literature for this area with a view to determining which of two hypotheses might be true. The first is that, for the population of those who stutter, unusual temperament is a causal factor for the development of the disorder and its later association with anxiety. The second hypothesis is that for the population of those who stutter the developmental manifestation of anxiety is an effect of stuttering. Both hypotheses attempt to account for the well-known association of anxiety with chronic stuttering.

RESULTS

A firm conclusion about the matter would be premature at present because the literature involved is limited and contains some inconsistencies. We suggest some quantitative and qualitative directions for future research. We argue also that the only way to resolve the matter is with longitudinal studies of cohorts ascertained prior to stuttering onset.

CONCLUSION

Conclusive findings about the matter can only emerge when research extends beyond its modest scope of 10 interpretable publications.

EDUCATIONAL OBJECTIVES

The reader will be able to: (a) describe temperament and the role it plays during anxiety development, (b) explain two alternative hypotheses which implicate temperament in early childhood stuttering; (c) describe current knowledge regarding temperament similarities and differences between stuttering and control children, and (d) discuss the theoretical and clinical implications of understand the relationship between temperament, anxiety and early stuttering.

Parental Perceptions of Overprotection: Specific to Anxious Children or Shared Between Siblings?

Parents of children with anxiety disorders (n = 45) and parents of nonclinical children (n = 33) were interviewed regarding the rearing of two children in their family. The purpose of the study was to determine whether overprotective parenting, according to parent report, occurs specifically in the context of relationships with the anxiety-disordered child or whether parents also perceive themselves to be overprotective of the anxious child's sibling. Self-reports of overprotection by parents of anxious children were also compared to self-reports of overprotection by parents of nonclinical children. Mothers in the clinical group were more likely to report that they were more protective of the anxious child than they were to report being either more protective of the sibling or equally protective of both children. Both mothers and fathers in the clinical group were no more likely than nonclinical parents to perceive themselves as being more protective overall than other parents.

Early temperamental and family predictors of shyness and anxiety

With a sample of 242 twins (135 girls, 107 boys) studied longitudinally, behavioral inhibition (BI) and inhibitory control (IC) measured at 3 years, as well as early and concurrent family process variables, were examined as predictors of shyness and of anxiety symptoms approximately 4 years later. Structured observational data from laboratory and home contexts were used in conjunction with parent and experimenter ratings. A key goal was to extend previous findings of the positive relationship between early BI and anxiety development by incorporating the consideration of IC and family process variables. Using hierarchical linear modeling with restricted maximum likelihood estimation to adjust for twin dependency, early BI (b = 0.37, p < .01), IC (b = 0.14, p < .05), and concurrent lower family stress (b = -0.22, p < .05) predicted shyness during middle childhood. Findings were similar for parent-rated and laboratory-based shyness measures. Anxiety symptoms were predicted by BI (b = 0.14, p < .05), early negative family affect (b = 0.20, p < .05), and family stress in middle childhood (b = 0.26, p < .05). These findings clarify the relative importance of temperament and family factors in the development of both shyness and anxiety symptoms during childhood.

A developmental twin study of symptoms of anxiety and depression: evidence for genetic innovation and attenuation

BACKGROUND

Little is known about the pattern of genetic and environmental influences on symptoms of anxiety and depression (SxAnxDep) from childhood to early adulthood.MethodParental- and self-reported levels of SxAnxDep were assessed at ages 8-9, 13-14, 16-17 and 19-20 years in 2508 twins from the Swedish Twin Study of Child and Adolescent Development (TCHAD). Analysis conducted using the Mx program included SxAnxDep by parental and self-report.

RESULTS

The best-fit model revealed one genetic risk factor for SxAnxDep acting at ages 8-9, 13-14, 16-17 and 19-20, and new sets of genetic risk factors 'coming on line' in early adolescence, late adolescence and early adulthood. Together, these genetic factors were very strong influences on the levels of SxAnxDep reported in common by parents and twins with heritability estimates, correcting for rater- and time-specific effects, ranging from 72% to 89%. The first genetic factor, which accounted for 72% of the variance in SxAnxDep at ages 8-9, attenuated sharply in influence, accounting for only 12% of the variance by ages 19-20. No evidence was found for shared environmental influences. Although not statistically significant, the correlation between genetic risk factors for SxAnxDep in males and females declined with advancing age.

CONCLUSIONS

Genetic effects on SxAnxDep are developmentally dynamic from middle childhood to young adulthood, demonstrating both genetic innovation and genetic attenuation. The attenuation might explain the low levels of continuity observed for anxiety and depressive disorders from childhood to adulthood. Differences in genetic risk factors for SxAnxDep in males and females may increase during development.

Assessing gene-environment interactions on anxiety symptom subtypes across childhood and adolescence

Consistent evidence shows both genetic and stress-related risks on child and adolescent anxiety, yet few studies have considered the degree to which genetic effects are moderated by stress (gene-environment interaction). We used longitudinal data from both a child and adolescent sample of twins to examine three novel issues on the presence of gene-environment interaction on anxiety symptoms. First, we assessed moderation of genetic risks on anxiety symptoms by negative life events in each age group. Second, by distinguishing between "stable" and "age-specific" genetic factors, we explored the continuity of gene-environment interaction across time and/or its emergence at specific ages. Third, we compared the presence of gene-environment interaction across different symptom types (general, panic, social, and separation). Genetic effects on separation anxiety symptoms in childhood (mean age = 8 years, 6 months) and panic anxiety symptoms in adolescence (mean age = 15 years) increased across independent negative life events. Shared environmental effects on separation anxiety symptoms and non shared environmental effects on general anxiety symptoms in adolescence were also moderated by negative life events. We interpret these preliminary findings tentatively in the context of gene-environment interaction on anxiety in general, and on early separation and later panic anxiety in particular.

A multivariate genetic analysis of specific phobia, separation anxiety and social phobia in early childhood

BACKGROUND

Comorbidity amongst anxiety disorders is very common in children as in adults and leads to considerable distress and impairment, yet is poorly understood. Multivariate genetic analyses can shed light on the origins of this comorbidity by revealing whether genetic or environmental risks for one disorder also influence another. We examined the genetic and environmental influences on the comorbidity between three common childhood anxiety disorders: Specific Phobia, Separation Anxiety and Social Phobia.

METHODS

Using a two-phase design 4,662 twin-pairs were screened in the first phase and 854 pairs were assessed in the second phase by maternal-informant diagnostic interview using DSM-IV criteria.

RESULTS

Multivariate genetic analysis revealed significant shared environmental over-lap between Specific Phobia and Separation Anxiety and significant familial and non-shared environmental over-lap between Specific Phobia and Social Phobia.

CONCLUSIONS

Familial influences, especially shared environment, are central to the comorbidity between Specific Phobia and both Separation Anxiety and Social Phobia.

Genetic influences on anxiety in children: what we've learned and where we're heading

Anxiety is a common problem, typically beginning early in life. This article explores reasons for individual differences in levels of anxiety among children, by reviewing the genetic literature. The plethora of research to date has demonstrated clearly that both genes and environmental influences play important roles in explaining differences in levels of anxiety of various types among children. This has encouraged researchers to search for specific genes and environmental influences upon anxiety. Despite important progress in identifying links between anxiety and specific genes--including associations between serotonin and dopamine genes and different symptoms of anxiety--overall, progress has been slow because multiple genes of small effect size are likely to influence anxiety. This article explains how the hunt for genes involved in anxiety is likely to benefit from genetically sensitive research, which examines the co-occurrence of symptoms; includes measures of the environment; and examines endophenotypes and risk pathways.

Genetic and environmental influences on anxiety dimensions in Italian twins evaluated with the SCARED questionnaire

This study explored the factorial structure of the Italian version of the Screen for Child Anxiety-Related Emotional Disorders questionnaire (SCARED), and investigated the contributions of genetic and environmental influences of individual variation of anxiety dimensions as reported in the SCARED. Three hundred and seventy-eight twin pairs aged 8-17 from the Italian Twin Registry filled in the SCARED through a mail survey. Four, distinct empirical factors, that corresponded closely to the original SCARED subscales of Generalized Anxiety (GAD), Panic (PD), Social Phobia (SP), and Separation Anxiety (SAD) disorder emerged from Exploratory Factor Analysis. The empirically derived scores were analyzed by structural equation modeling; moderate-to-high heritability, without age or sex differences, emerged for all dimensions with the exception of GAD, for which an age effect was found. The DSM-IV anxiety dimensions identified by the SCARED have a psychometric structure that can be replicated in the Italian culture, and are influenced at different extents by genetic and nonshared environmental determinants.

Genetic and environmental contributions to common psychopathologies of childhood and adolescence: a study of twins and their siblings

We report findings based on analyses of self-reports of six common adolescent psychopathologies (attention deficit/hyperactivity disorder, ADHD; conduct disorder, CD; oppositional defiant disorder, ODD; generalized anxiety disorder, GAD; separation anxiety disorder, SAD; and major depressive disorder, MDD) in a sample of 1,162 male and female adolescent (12-19 years) twin pairs and 426 siblings. Prevalence statistics for past year and lifetime reports confirm differences between genders for CD, GAD, SAD, and MDD, and a lack of differences between twins and their non-twin siblings. Biometrical modeling was conducted to ascertain the relative influences of genes, and shared and non-shared environments contributing to these disorders. A more robust estimate of these parameters was obtained by including non-twin siblings. Age-specific thresholds were integrated into the analyses to appropriately model the developmental patterns of behavior. We found evidence for both genetic and non-shared environmental influences for all disorders. Shared environmental influences also seem to be important for MDD and lifetime GAD.

The developmental association between eating disorders symptoms and symptoms of depression and anxiety in juvenile twin girls

OBJECTIVE

We investigated the role of genetic and environmental factors in the developmental association among symptoms of eating disorders, depression, and anxiety syndromes in 8-13-year-old and 14-17-year-old twin girls.

METHODS

Multivariate genetic models were fitted to child-reported longitudinal symptom data gathered from clinical interview on 408 MZ and 198 DZ female twin pairs from the Virginia Twin Study of Adolescent Behavioural Development (VTSABD).

RESULTS

Model-fitting revealed distinct etiological patterns underlying the association among symptoms of eating disorders, depression, overanxious disorder (OAD), and separation anxiety disorder (SAD) during the course of development: 1) a common genetic factor influencing liability to all symptoms - of early and later OAD, depression, SAD, and eating symptoms; 2) a distinct genetic factor specifically indexing liability to early eating disorders symptoms; 3) a shared environmental factor specifically influencing early depression and early eating disorders symptoms; and 4) a common environmental factor affecting liability to symptoms of later eating disorders and both early and later separation anxiety.

CONCLUSIONS

These results suggest a pervasive genetic effect that influences liability to symptoms of over-anxiety, separation anxiety, depression, and eating disorder throughout development, a shared environmental influence on later adolescent eating problems and persistent separation anxiety, genetic influences specific to early eating disorders symptoms, and a shared environmental factor influencing symptoms of early eating and depression.

Separation anxiety disorder, panic disorder, and school refusal

Studies attest to the chronic nature of anxiety in youth. Consequently, there is a growing literature examining causative pathways to these disorders and efficacious treatments for them. This review examines separation anxiety disorder, a commonly occurring childhood anxiety disorder, and panic disorder, a more rare anxiety disorder in youth. Finally, school refusal, which may be tied to an internalizing or externalizing disorder or no disorder at all, is examined.

Predicting toddler anxiety/depressive symptoms: Effects of caregiver sensitivity on temperamentally vulnerable children

This research examines whether maternal sensitivity in early childhood reduces later anxiety/depressive symptoms for children with more temperamental vulnerability, and whether these effects are different for boys and girls. Data from the National Institute of Child Health and Human Development Early Child Care study with 1,226 subjects (631 boys, 595 girls) were analyzed. Mothers and other caregivers rated children's difficult temperament at 1 and 6 months. Trained observers scored maternal sensitivity when children were 6 and 15 months. Child anxiety/depressive symptoms were rated by mothers and other caregivers when children were 2 and 3 years of age. Maternal sensitivity in early childhood significantly predicted decreased 2- and 3-year-old anxiety/depressive symptoms. Children with more difficult temperament were significantly more likely to show decreased anxiety/depressive symptoms at 2 years of age if their mothers had been more sensitive. Maternal sensitivity also was a significant predictor of decreased anxiety/depressive symptoms for more temperamentally difficult boys, and temperamentally difficult boys with more sensitive mothers were found to be significantly more likely than girls to show decreased anxiety/depressive symptoms at 3 years of age. The findings of this pilot research suggest that facilitating and supporting increased sensitivity for mothers with more temperamentally difficult children could be beneficial. ©2005 Michigan Association for Infant Mental Health.

Risk for separation anxiety disorder among girls: paternal absence, socioeconomic disadvantage, and genetic vulnerability

The authors examined genetic and environmental influences, including the contributions of 2 measured aspects of the shared environment of twins (paternal absence, socioeconomic disadvantage) on the development of mother-reported separation anxiety disorder (SAD) history in a sample of 1,887 female twin pairs. Four different symptom categories of SAD were considered. Results revealed that all 4 SAD symptom categories were significantly heritable, whereas the contribution of shared environmental influences to the variation in risk was significant for only 2 of the 4 SAD categories. Paternal absence was found to have an important influence in vulnerability for SAD, whereas the effect of socioeconomic disadvantage was less robust. Evidence for race differences in the etiology of SAD was not found.

Family and high-risk studies of social anxiety disorder

OBJECTIVE

To present data on the role of familial factors in the etiology of social anxiety disorder.

METHOD

Findings presented from a family/high-risk study (the Yale Family Study) and a prospective community study of youth (the Munich Early Developmental Stages of Psychopathology (EDSP) Study).

RESULTS

The Yale Family Study demonstrated a substantial degree of familial aggregation of social anxiety disorder and specificity with respect to other anxiety subtypes among adult relatives. The Yale high-risk component and the EDSP Study confirm the association between parental and offspring social anxiety, but did not yield consistent evidence for an association between familial environmental factors and social anxiety.

CONCLUSION

Future studies are needed to examine mechanisms for the specificity of social anxiety disorder aggregation, to identify vulnerability factors for its development and to pinpoint environmental conditions that may enhance or suppress expression of underlying vulnerability.

A twin study of anxiety-related behaviours in pre-school children

BACKGROUND

From middle childhood onwards, substantial evidence points to phenotypic differentiation between anxiety diagnostic categories such as generalised anxiety, separation anxiety, specific phobia, and obsessive-compulsive disorders. However, little is known about the genetics of these categories and especially about the phenotypic and genetic structure of related behaviours in pre-school children.

METHODS

We examined the phenotypic differentiation and genetics of mother-reported anxiety-related behaviours in 4,564 four-year-old twin pairs, from a population-based sample.

RESULTS

Confirmatory factor analyses provided support for five correlated factors: General Distress, Separation Anxiety, Fears, Obsessive-Compulsive Behaviours, and Shyness/Inhibition. Genetic influences were found on all five factors, but the pattern of influences differed considerably across them, with particularly high heritability estimates for Obsessive-Compulsive Behaviours and Shyness/Inhibition, and substantial shared environmental influence on Separation Anxiety. Multivariate genetic analyses revealed moderate genetic correlations between the five factors. Genetic overlap was particularly pronounced between General Distress and the other anxiety-related behaviours, accounting for about half of their covariance. Genetic variance on Obsessive-Compulsive Behaviours was the least correlated with the other scales. The shared environmental influences correlated highly across the factors, accounting for the greatest proportion of covariation between Separation Anxiety, Fears and Obsessive-Compulsive Behaviours. The non-shared environment influences were largely variable specific.

CONCLUSIONS

These data provide evidence for phenotypic and genetic overlap as well as differentiation between aspects of anxiety-related behaviours in young children. We conclude that research with young children will benefit from more specific assessments of anxiety-related behaviours in addition to less differentiated assessments of 'internalising' symptoms.

Genetic animal models of anxiety

The focus of this review is on progress achieved in identifying specific genes conferring risk for anxiety disorders through the use of genetic animal models. We discuss gene-finding studies as well as those manipulating a candidate gene. Both human and animal studies thus far support the genetic complexity of anxiety. Clinical manifestations of these diseases are likely related to multiple genes. While different anxiety disorders and anxiety-related traits all appear to be genetically influenced, it has been difficult to ascertain genetic influences in common. Mouse studies have provisionally mapped several loci harboring genes that affect anxiety-related behavior. The growing array of mutant mice is providing valuable information about how genes and environment interact to affect anxious behavior via multiple neuropharmacological pathways. Classical genetic methods such as artificial selection of rodents for high or low anxiety are being employed. Expression array technologies have as yet not been employed, but can be expected to implicate novel candidates and neurobiological pathways.

Evaluation of Lewis and SHR rat strains as a genetic model for the study of anxiety and pain

The study of inbred strains of rodents that differ for specific behaviours can help us to understand the biological mechanisms underlying complex psychological traits. Lewis (LEW) and SHR inbred rat strains, for example, have been recently proposed as a genetic model for the study of anxiety. Our goal was to characterise two Brazilian substrains of LEW and SHR rats, that have never been compared before, behaviourally and/or pharmacologically, in order to evaluate their potential contribution to studies on anxiety and pain. Male and female LEW and SHR rats were submitted after 8 weeks of age to five anxiety/emotionality tests: the open field (7 or 260 lux), the elevated plus-maze, the elevated T-maze and the black/white box. Rats of all groups were also submitted to the formalin test of nociception and measurement of blood pressure. Significant strain differences (P<0.05) were observed in both sexes for all indices of anxiety and also for measures of pain and blood pressure. SHRs, compared with LEWs, explored more the aversive environments of all anxiety tests, showed less nociceptive responses and were hypertensive. All differences in experimental anxiety parameters agree with previous differences reported between two French LEW and SHR substrains, suggesting that LEWs are more anxious than SHRs, thus consolidating these strains as a useful genetic model for the study of anxiety and pain. The possible involvement of tachykinergic mechanisms is discussed.

A longitudinal study of the etiology of separation anxiety

A longitudinal examination of the relation between separation experiences and the development of separation anxiety at age 3, 11 and 18 years was conducted. Three associative pathways were assessed. Conditioning events were not related to separation anxiety at age 3. Vicarious learning (modelling) in middle childhood (age 9 years) was the conditioning variable most strongly related to separation anxiety at age 11, accounting for 1.8% of the variance in symptoms. Separation experiences (hospitalisations) before the age of 9 were inversely correlated with separation anxiety at age 18. That is, more overnight hospital stays in childhood were related to less separation anxiety in late adolescence. However, none of these conditioning correlates remained significant predictors of separation anxiety in adjusted regression models. In contrast, certain "planned" separations in early-mid childhood were associated with lower levels of separation anxiety at later ages. Generally, the findings were consistent with predictions from the non-associative theory of fear acquisition. That vicarious learning processes appeared to modulate, albeit to a minor degree, the expression of separation anxiety during mid-late childhood suggests that there may be critical periods during which some individuals are susceptible to the interactive effects of both associative and non-associative processes. These findings serve to illustrate the complexity of fear acquisition, the relevance of developmental factors and the likely interplay between associative and non-associative processes in the etiology of fear and anxiety.

Generalized anxiety disorder in children and adolescents

Children and adolescents with GAD suffer from excessive, pervasive worries that interfere with social, academic, and family functioning. The comorbidity rate with other anxiety disorders and major depression is high. The course tends to be chronic, and evidence shows continuity between anxiety disorders in youth and adulthood. Individual and group CBT and the incorporation of family anxiety management training have demonstrated efficacy in the treatment of childhood GAD. No double-blind, placebo-controlled, pharmacotherapy trials with adequate sample sizes for children and adolescents with GAD have been published. Preliminary data support the potential efficacy of selective serotonin reuptake inhibitors, buspirone, and high-potency benzodiazepines. Adequately powered, controlled, pharmacologic treatment trials are necessary. Future research should be directed toward comparing the relative efficacy of psychotherapy, pharmacotherapy, and both in the treatment of GAD in youth.

Linking temperamental fearfulness and anxiety symptoms: a behavior-genetic perspective

Research on mood and anxiety disorders has historically proceeded without sufficient reference to the growing body of work on the nature of typical emotional development and temperament. Reviewing data from several studies, we consider experiential, biological, and genetic factors as providing causal input to typical developmental variation in fearfulness and anxiety during infancy and early childhood. Longitudinal behavioral methods, psychophysiologic measures, and a behavior-genetic framework are used to approach these issues. Results from twin studies implicate moderately strong genetic influences on different facets of temperamental fearfulness, as well as childhood anxiety symptoms. Then, we consider the distinction between normal range temperament and overt anxiety symptoms from a quantitative genetic perspective. Biological correlates (cortisol, asymmetric frontal EEG activation, cardiac reactivity) of inhibited behavior are considered as related endophenotypes for anxiety. In a nongenetic analysis, we report the prediction of internalizing problems during kindergarten from earlier temperament and earlier basal cortisol measures. Our review highlights connections between behavioral indicators and various putative endophenotypes and the fuzzy boundary between normal-range temperament and anxiety disorders.

Role of the family in the onset and outcome of childhood disorders: selected research findings

OBJECTIVE

Three areas of basic family research were selected for review as being of special importance to the clinically oriented child and adolescent psychiatrist: behavioral genetics, expressed emotion, and the interaction of family dynamics and childhood illness.

METHOD

Medline and PSYCINFO searches using appropriate keywords were obtained for each of the 3 major areas. All English-language articles published after 1989 that included empirical research pertaining to children or adolescents were reviewed.

RESULTS

Behavioral genetics research indicates that the shared environment, including issues of parental monitoring and discipline, is important in the development and outcome of externalizing disorders. Differential parental treatments of one sibling are critical in internalizing disorders. Criticism (as measured by expressed emotion) is associated with poor outcome of many childhood medical and psychiatric disorders. Chronic illness in a child changes the family dynamics toward being more structured and less emotionally warm and communicative. The family's role in adherence to treatment is critical, and families with high levels of criticism have more difficulty.

CONCLUSIONS

Families can cause problems, but many times the problems families have are in response to a child's problems. There is a continued need to empirically assess which family processes are important for specific childhood disorders.

Childhood anxiety disorders: lessons from the literature

Studies of childhood anxiety disorders have increased in recent years, but the clinical implications of the work are sometimes difficult to discern. This paper reviews salient findings (related to the assessment and management of anxious children) published in the last 5 years. The high comorbidity among disorders, the occurrence of different disorders in the same child over time, recent changes in diagnostic categories, the availability of new anxiety measures, and poor correspondence between parent and child reports of symptoms all underscore the need for thorough assessment. Increasing evidence supports cognitive-behavioural treatments for anxiety disorders, alone or in combination with pharmacotherapy. Other important aspects of management suggested by developmental studies of anxious children include psychoeducation about constitutional factors in the development of anxiety, interventions to address parental anxiety, parenting advice regarding behaviour management and reduction of family conflict, and treatment of child impairment to decrease the risk of depression. Questions requiring further research are identified.

Specific life events and chronic experiences differentially associated with depression and anxiety in young twins

Behavioral genetic analyses indicate that environmental influences associated with depression and anxiety are specific to each symptom type; however, this has not been tested specifically in children. Sixty-one (61) child twin pairs in which at least one twin had a very high anxiety or depression score, and 29 nonanxious, nondepressed pairs were interviewed about life events and chronic stressors in the previous 12 months. Loss events, schoolwork stressors, family relationship problems, and friendship problems were all significantly associated with depression but not anxiety. Threat events were significantly associated with anxiety but not depression. Loss events and schoolwork stressors appeared to act as shared environment influences in that they made twin pairs resemble one another. Threat events, friendship problems, and family relationship problems were individual specific and accounted for differences within the pairs. These results clarify the associations between life events and depressive and anxious symptoms in children and adolescents and reveal specific associations previously unidentified in this age range.

The Child and Adolescent Psychiatric Assessment (CAPA)

OBJECTIVE

To describe the Child and Adolescent Psychiatric Assessment (CAPA). The base interview covers the age range from 9 to 17 years.

METHOD

The interview glossary that provides detailed operational definitions of symptoms and severity ratings is described, and psychometric data and further developments of the interview are presented.

RESULTS

Across 5,962 parent-child interviews, the core sections of the CAPA (psychiatric symptoms, functional impairment, demographics, family structure and functioning) took on average 59 minutes for children and 66 minutes for parents. Test-retest reliability for diagnoses ranged from kappa = 0.55 for conduct disorder (CD) to kappa = 1.0 for substance abuse/dependence. Validity as judged by 10 different criteria was good. Developments of the CAPA include a shorter "gateway" version using core symptoms as screen items, a Spanish version, and versions for twin studies, use with young adults (YAPA), and preschool-age children (PAPA).

CONCLUSIONS

There is a place in both research and clinical settings for a rigorously operationalized interview (such as the CAPA) that focuses on ensuring that respondents understand what is being asked and on clearly defining levels of symptom severity and functional impairment.

Using genetic analyses to clarify the distinction between depressive and anxious symptoms in children

Self-report measures of depression and anxiety in children are highly correlated and distinguishing between shared and independent factors in their etiologies is therefore problematic. The aim of this article was to test whether less correlated measures of depression and anxiety could be produced and, if so, what genetic and environmental factors would account for the variance in these symptoms. Second-order factor analysis of the items from two standardized self-report questionnaires of depression and anxiety collected from 395 pairs of same-sex twins aged 8 to 16 years resulted in purer dimensions of depression and anxiety. Behavioral genetic analyses confirmed the distinction between these two dimensions, and bivariate analyses revealed that the association between the two was primarily accounted for by shared genetic factors.

Behavioral genetic analyses of self-reported anxiety at 7 years of age

OBJECTIVE

To conduct behavioral genetic analyses of self-reported childhood anxiety at 7 years of age.

METHOD

Three hundred twenty-six same-sex twin pairs (174 monozygotic, 152 dizygotic) completed the Revised Children's Manifest Anxiety Scale at 7 years of age. Behavioral genetic analyses were conducted on the total and subscale scores.

RESULTS

Monozygotic within-pair correlations were higher than dizygotic correlations for physiological and social anxiety symptoms, suggesting heritable influences on these aspects. These results were found to be statistically significant with structural equation modeling.

CONCLUSION

Certain symptoms of self-reported anxiety in children 7 years of age seem to result, at least in part, from genetic factors. Physiological and social anxiety symptoms, which may be related to behavioral inhibition, appear to be genetically influenced. These results are linked to previous findings in older children and adults.

Genetic and environmental influences on ratings of manifest anxiety by parents and children

Parental reports and children's self-reports of manifest anxiety were obtained from a community-based sample of twin pairs on two occasions approximately 19 months apart, using the Revised Child Manifest Anxiety Scale (Reynolds & Richmond, 1978). In prior cross-sectional studies, a low degree of agreement between parent and child assessments of anxiety was found. Furthermore, parental reports were found to reflect a higher heritability than children's self-reports (Eaves et al., 1997; Thapar & McGuffin, 1995). The index of temporal stability was moderate for all informants (circa r = .5 to r = .6). To test whether the components contributing to the temporal stability differed between the informants, structural equation models were fitted to the data using the program, Mx: Statistical Modeling (Neale, 1995). The results showed substantial differences in genetic effects according to both gender and informant. For children's self-reports, temporal stability was largely a function of environmental effects, with genetic effects contributing a modest 20%, whereas for parental reports, temporal stability was largely a function of genetic effects. The heritability was higher for parental reports than for boys' self-reports and the genetic covariance between parents and their sons was near zero, indicating that they were reporting on quite different aspects of anxiety. However, for girls, heritability for maternal reports was lower than for self-reports, and the genetic covariance between mother and daughter was about the same as that between mothers and fathers, meaning that they were assessing the same genetically influenced aspect of anxiety. These results highlight the need to focus on gender differences.

Behavioral genetics as a tool for developmental psychology: anxiety and depression in children and adolescents

Over the past decade there has been a huge increase in the number of behavioral genetic studies looking into anxiety and depression in children and adolescents. There are now enough data in this area to make a review of the results useful. This paper begins with an outline of the methods used in such research and moves on to review the results in extant studies. Overall, these studies indicate modest to moderate genetic influence on both anxiety and depression. However, behavioral genetic methods are also paramount for exploring environmental influences in addition to genetic influences. Shared environment (that which makes family members resemble one another) is rarely identified in adult studies of personality or psychopathology and does not appear to be a significant influence for depression but it is for anxiety. Nonshared environment, which makes family members differ from one another, is found to be a significant influence for both anxiety and depression. Patterns within these results due to rater effects, age effects, sex effects, the precise phenotype measured, and the study design are explored.