Progressive habituation to separation alleviates the negative effects of weaning in the mother and foal

Early and definitive separation between offspring and their mothers has negative consequences on behavioral and physiological responses. This study compared sudden and definitive weaning (Sudd group, N = 16) and weaning involving progressive habituation to separation using a fence line during the month preceding definitive separation (Prog group, N = 18). The impact of these two methods was assessed in both foals and their mothers through behavioral and biological parameters, including salivary cortisol, telomere length and blood transcriptomes. On the day of definitive separation, Prog foals neighed and trotted less and presented lower cortisol levels than Sudd foals. The weaning type also acted on the foals' personality development; Prog foals became more curious, less fearful and less gregarious than Sudd foals, and the effects remained visible for at least 3 months. In principal component analysis, the Sudd and Prog groups were well separated along a factor where fear, reactivity and gregariousness correlated with high cortisol levels, but curiosity was associated with an increased telomere length and higher expression of genes involved in mitochondrial functions. Progressive weaning was also beneficial in mares. Principal component analysis showed that most Sudd group mares had higher cortisol levels and displayed more alert postures, neighs and activity on the day of weaning, indicating higher stress levels, while Prog mares had profiles that were characterized by more time spent resting on the day of weaning and longer telomere lengths. In conclusion, this study shows that progressive habituation to separation alleviates the negative effect of definitive weaning on both the mother and her young compared to sudden separation.

Interaction between the Opioid Receptor OPRM1 Gene and Mother-Child Language Style Matching Prospectively Predicts Children's Separation Anxiety Disorder Symptoms

Recent research suggests that lower mother-child language style matching (LSM) is associated with greater physiological reactivity and insecure attachment in school-aged children, but to date no studies have explored this measure of parent-child behavioral matching for its association with children's anxiety symptoms, a well-known correlate of attachment insecurity and heightened physiological reactivity. There is also considerable evidence of genetic risk for anxiety, including possession of the OPRM1 minor allele, 118G. In the current study (N = 44), we expand upon what is known about children's genetic and environmental risk for anxiety by examining the unique and interactive effects of mother-child LSM and the OPRM1 polymorphism A118G on school-aged children's separation anxiety disorder (SAD) symptoms. SAD symptoms were measured both concurrently with LSM and OPRM1 genotype and two years later through self-report. No significant associations emerged between LSM or OPRM1 and concurrent Time 1 SAD symptoms. However, lower LSM and 118G minor allele possession were both associated with greater SAD symptoms at Time 2; further, the interaction between LSM and OPRM1 genotype significantly predicted SAD symptoms beyond the main effects of the two variables. Possession of the minor allele was only associated with greater SAD symptoms among children in low LSM dyads, whereas children with the minor allele in high LSM dyads showed non-significantly lower SAD symptoms. These findings and a proportion affected analysis provide support for a differential susceptibility model of gene by environment interactions for the OPRM1 gene. We discuss the implications for predicting children's separation anxiety across development.

The stability and change of etiological influences on depression, anxiety symptoms and their co-occurrence across adolescence and young adulthood

BACKGROUND

Depression and anxiety persist within and across diagnostic boundaries. The manner in which common v. disorder-specific genetic and environmental influences operate across development to maintain internalizing disorders and their co-morbidity is unclear. This paper investigates the stability and change of etiological influences on depression, panic, generalized, separation and social anxiety symptoms, and their co-occurrence, across adolescence and young adulthood.

METHOD

A total of 2619 twins/siblings prospectively reported symptoms of depression and anxiety at mean ages 15, 17 and 20 years.

RESULTS

Each symptom scale showed a similar pattern of moderate continuity across development, largely underpinned by genetic stability. New genetic influences contributing to change in the developmental course of the symptoms emerged at each time point. All symptom scales correlated moderately with one another over time. Genetic influences, both stable and time-specific, overlapped considerably between the scales. Non-shared environmental influences were largely time- and symptom-specific, but some contributed moderately to the stability of depression and anxiety symptom scales. These stable, longitudinal environmental influences were highly correlated between the symptoms.

CONCLUSIONS

The results highlight both stable and dynamic etiology of depression and anxiety symptom scales. They provide preliminary evidence that stable as well as newly emerging genes contribute to the co-morbidity between depression and anxiety across adolescence and young adulthood. Conversely, environmental influences are largely time-specific and contribute to change in symptoms over time. The results inform molecular genetics research and transdiagnostic treatment and prevention approaches.

Personality dimensions as common and broadband-specific features for internalizing and externalizing disorders

Several researchers have suggested that the nature of the covariation between internalizing and externalizing disorders may be understood better by examining the associations between temperament or personality and these disorders. The present study examined neuroticism as a potential common feature underlying both internalizing and externalizing disorders and novelty seeking as a potential broad-band specific feature influencing externalizing disorders alone. Participants were 12- to 18-year-old twin pairs (635 monozygotic twin pairs and 691 dizygotic twin pairs; 48 % male and 52 % female) recruited from the Colorado Center for Antisocial Drug Dependence. Genetic and nonshared environmental influences shared in common with neuroticism influenced the covariation among distinct internalizing disorders, the covariation among distinct externalizing disorders, and the covariation between internalizing and externalizing disorders. Genetic influences shared in common with novelty seeking influenced the covariation among externalizing disorders and the covariation between major depressive disorder and externalizing disorders, but not the covariation among internalizing disorders or between anxiety disorders and externalizing disorders. Also, after accounting for genetic and environmental influences shared in common with neuroticism and novelty seeking, there were no significant common genetic or environmental influences among the disorders examined, suggesting that the covariance among the disorders is sufficiently explained by neuroticism and novelty seeking. We conclude that neuroticism is a heritable common feature of both internalizing disorders and externalizing disorders, and that novelty seeking is a heritable broad-band specific factor that distinguishes anxiety disorders from externalizing disorders.

Childhood separation anxiety disorder and adult onset panic attacks share a common genetic diathesis

BACKGROUND

Childhood separation anxiety disorder (SAD) is hypothesized to share etiologic roots with panic disorder. The aim of this study was to estimate the genetic and environmental sources of covariance between childhood SAD and adult onset panic attacks (AOPA), with the primary goal to determine whether these two phenotypes share a common genetic diathesis.

METHODS

Participants included parents and their monozygotic or dizygotic twins (n = 1,437 twin pairs) participating in the Virginia Twin Study of Adolescent Behavioral Development and those twins who later completed the Young Adult Follow-Up (YAFU). The Child and Adolescent Psychiatric Assessment was completed at three waves during childhood/adolescence followed by the Structured Clinical Interview for DSM-III-R at the YAFU. Two separate, bivariate Cholesky models were fit to childhood diagnoses of SAD and overanxious disorder (OAD), respectively, and their relation with AOPA; a trivariate Cholesky model also examined the collective influence of childhood SAD and OAD on AOPA.

RESULTS

In the best-fitting bivariate model, the covariation between SAD and AOPA was accounted for by genetic and unique environmental factors only, with the genetic factor associated with childhood SAD explaining significant variance in AOPA. Environmental risk factors were not significantly shared between SAD and AOPA. By contrast, the genetic factor associated with childhood OAD did not contribute significantly to AOPA. Results of the trivariate Cholesky reaffirmed outcomes of bivariate models.

CONCLUSIONS

These data indicate that childhood SAD and AOPA share a common genetic diathesis that is not observed for childhood OAD, strongly supporting the hypothesis of a specific genetic etiologic link between the two phenotypes.

Unstable maternal environment, separation anxiety, and heightened CO2 sensitivity induced by gene-by-environment interplay

BACKGROUND

In man, many different events implying childhood separation from caregivers/unstable parental environment are associated with heightened risk for panic disorder in adulthood. Twin data show that the occurrence of such events in childhood contributes to explaining the covariation between separation anxiety disorder, panic, and the related psychobiological trait of CO(2) hypersensitivity. We hypothesized that early interference with infant-mother interaction could moderate the interspecific trait of response to CO(2) through genetic control of sensitivity to the environment.

METHODOLOGY

Having spent the first 24 hours after birth with their biological mother, outbred NMRI mice were cross-fostered to adoptive mothers for the following 4 post-natal days. They were successively compared to normally-reared individuals for: number of ultrasonic vocalizations during isolation, respiratory physiology responses to normal air (20%O(2)), CO(2)-enriched air (6% CO(2)), hypoxic air (10%O(2)), and avoidance of CO(2)-enriched environments.

RESULTS

Cross-fostered pups showed significantly more ultrasonic vocalizations, more pronounced hyperventilatory responses (larger tidal volume and minute volume increments) to CO(2)-enriched air and heightened aversion towards CO(2)-enriched environments, than normally-reared individuals. Enhanced tidal volume increment response to 6%CO(2) was present at 16-20, and 75-90 postnatal days, implying the trait's stability. Quantitative genetic analyses of unrelated individuals, sibs and half-sibs, showed that the genetic variance for tidal volume increment during 6%CO(2) breathing was significantly higher (Bartlett χ = 8.3, p = 0.004) among the cross-fostered than the normally-reared individuals, yielding heritability of 0.37 and 0.21 respectively. These results support a stress-diathesis model whereby the genetic influences underlying the response to 6%CO(2) increase their contribution in the presence of an environmental adversity. Maternal grooming/licking behaviour, and corticosterone basal levels were similar among cross-fostered and normally-reared individuals.

CONCLUSIONS

A mechanism of gene-by-environment interplay connects this form of early perturbation of infant-mother interaction, heightened CO(2) sensitivity and anxiety. Some non-inferential physiological measurements can enhance animal models of human neurodevelopmental anxiety disorders.

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.

Memory deficits in children with and at risk for anxiety disorders

There are limited data on the neurocognitive correlates of childhood anxiety disorders. The objective of this study was to examine whether visual and verbal memory deficits of nonemotional stimuli are (1) a shared feature of three common childhood anxiety disorders (social phobia, separation anxiety disorder, and generalized anxiety disorder) or whether these deficits are restricted to specific anxiety disorders, and (2) present in offspring who possess at least one of the following established risk factors for anxiety disorders, parental history of panic disorder (PD), or major depressive disorder (MDD). One hundred and sixty offspring, ages 9-20 years, were recruited from parents with lifetime diagnoses of PD, MDD, PD plus MDD, or neither illness. Different clinicians blindly administered semistructured diagnostic interviews to offspring and parents. Verbal and visual memory subtests of the Wide Range Assessment of Memory and Learning were administered to offspring. The results showed that offspring with ongoing social phobia demonstrated reduced visual but not verbal memory scores compared to those without social phobia when controlling for offspring IQ, separation anxiety disorder, and generalized anxiety disorder. No other offspring anxiety disorder predicted memory performance. Neither parental PD nor parental MDD was associated with offspring memory performance. These findings are relevant to understanding the phenomenology of childhood anxiety disorders and may provide insights into the neural circuits underlying these disorders.

Early life stress alters adult serotonin 2C receptor pre-mRNA editing and expression of the alpha subunit of the heterotrimeric G-protein G q

Infant maternal separation, a paradigm of early life stress in rodents, elicits long-lasting changes in gene expression that persist into adulthood. In BALB/c mice, an inbred strain with spontaneously elevated anxiety and stress reactivity, infant maternal separation led to increased depression-like behavioral responses to adult stress and robustly increased editing of serotonin 2C receptor pre-mRNA. Chronic fluoxetine treatment of adult BALB/c mice exposed to early life stress affected neither their behavioral responses to stress nor their basal 5-HT2C pre-mRNA editing phenotype. However, when fluoxetine was administered during adolescence, depression-like behavioral responses to stress were significantly diminished in these mice, and their basal and stress-induced 5-HT2C pre-mRNA editing phenotypes were significantly lower. Moreover, when BALB/c mice exposed to early life stress were raised in an enriched postweaning environment, their depression-like behavioral responses to adult stress were also significantly diminished. However, their 5-HT2C pre-mRNA editing phenotype remained unaltered. Hence, the similar behavioral effects of enrichment and fluoxetine treatment during adolescence were not accompanied by similar changes in 5-HT2C pre-mRNA editing. Enriched and nonenriched BALB/c mice exposed to early life stress also exhibited significantly increased expression of mRNA and protein encoding the G alpha q subunit of G-protein that couples to 5-HT2A/2C receptors. In contrast, G alpha q expression levels were significantly lower in fluoxetine-treated mice. These findings suggest that compensatory changes in G alpha q expression occur in mice with persistently altered 5-HT2C pre-mRNA editing and provide an explanation for the dissociation between 5-HT2C receptor editing phenotypes and behavioral stress responses.

DRD4 7-repeat polymorphism moderates the association between maternal unresolved loss or trauma and infant disorganization

Previous studies have related attachment disorganization in children to either dopamine D4 receptor polymorphisms or maternal unresolved loss or trauma and frightening or anomalous parenting. In this study it was examined whether the interaction between genetic (DRD4 7-repeat and -521 C/T) and environmental risk factors (maternal unresolved loss/trauma and maternal frightening behavior) was associated with infant disorganization. A moderating role of the DRD4 gene was found. Maternal unresolved loss or trauma was associated with infant disorganization, but only in the presence of the DRD4 7-repeat polymorphism. The increase in risk for disorganization in children with the 7-repeat allele exposed to maternal unresolved loss/trauma compared to children without these combined risks was 18.8 fold. Similar moderating effects were not found for maternal frightening behavior. Our findings indicate that children are differentially susceptible to unresolved loss or trauma dependent on the presence of the 7-repeat DRD4 allele.

A controlled longitudinal 5-year follow-up study of children at high and low risk for panic disorder and major depression

BACKGROUND

To evaluate the longitudinal course of psychiatric disorders in children of parents with panic disorder (PD) and major depression (MD) as they transition through the period of risk from childhood into adolescence.

METHOD

Over a 5-year follow-up, we compared psychiatric disorders in four groups of children: (1) offspring of parents with PD plus MD (n=136); (2) offspring of parents with PD without MD (n=27); (3) offspring of parents with MD but without PD (n=53); and (4) offspring of non-PD non-MD parents (n=103).

RESULTS

Parental PD was significantly associated with increased risk for anxiety disorders, irrespective of parental MD. Parental MD was associated with increased risk for MD, disruptive behavior disorders, and deficits in psychosocial functioning, irrespective of parental PD.

CONCLUSIONS

These longitudinal findings confirm and extend previous cross-sectional results documenting significant associations between PD and MD in parents and patterns of psychopathology and dysfunction in their offspring.

Effects of parental anxiety disorders in children at high risk for panic disorder: a controlled study

BACKGROUND

To examine the association between anxiety disorders in parents and offspring in a sample of children at risk for panic disorder. We hypothesized that individual anxiety disorders will breed true in offspring.

METHODS

Comparisons were made between offspring of parents with PD+MD (N=136), PD (N=27), MD (N=27), and Controls (N=103). All subjects were assessed with structured diagnostic interviews. Individual anxiety disorders in the offspring were used as dependent variables in logistic regression models where parental PD status, parental MD, and the same parental anxiety diagnosis were used as independent binary variables.

RESULTS

Social phobia and separation anxiety disorder in the offspring were accounted for by the same disorders in the parent, whereas agoraphobia and OCD in the offspring were accounted for by parental panic disorder.

CONCLUSIONS

These findings suggest that differing risk factors underlie the expression of individual anxiety disorders in children at risk for panic disorder.

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.

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.

The heritability of gender identity disorder in a child and adolescent twin sample

The heritability and prevalence of the gender identity disorder (GID) was examined, as well as its comorbidity with separation anxiety and depression, in a nonretrospective study of child and adolescent twins. The parents of 314 twins (ages 4-17 years; 96 monozygotic pairs [MZ] and 61 dizygotic [DZ] pairs) completed the Coolidge Personality and Neuropsychological Inventory (CPNI) containing a six-item DSM-IV-based GID scale. Prevalence of clinically significant GID symptomatology in the twin sample was estimated to be 2.3%. Univariate model fitting analyses were conducted using an ordinal transformation of the GID scale. The model that best described the data included a significant additive genetic component accounting for 62% of the variance and a nonshared environmental component accounting for the remaining 38% of the variance. Results suggested no heterogeneity in the parameter estimates resulting from age. The correlation between GID and depression was modest, but significant (r = .20; P < .05), whereas the correlation between GID and separation anxiety was nonsignificant (P > .05). Overall, the results support the hypothesis that there is a strong heritable component to GID. The findings may also imply that gender identity may be much less a matter of choice and much more a matter of biology.

Genetic and environmental influences on separation anxiety disorder symptoms and their moderation by age and sex

We estimated genetic and environmental influences on mother-rated DSM-III-R separation anxiety disorder (SAD) symptoms in 2043 3 to 18-year-old male and female twin pairs and their siblings (348 pairs) recruited from the Australian NH&MRC Twin Registry. Using DeFries and Fulker's (1985) multiple regression analysis, we found that genetic and shared environmental influences both contributed appreciably to variation in SAD symptoms (h2 = .47, SE = .07; c2 = .21, SE = .05) and were significantly moderated by both sex and age. Genetic influences were greater for girls than boys (h2 = .50 and .14, respectively), whereas shared environmental influences were greater for boys than girls (c2 = .51 and .21, respectively). Genetic influences increased with age. whereas shared environmental influences decreased with age. Shared environmental influences were greater in magnitude for twins than for nontwin siblings (c2 = .28 versus .13, respectively). Implications of these findings for theories of the cause of separation anxiety are discussed.

Parent-child concordance for separation anxiety: a clinical study

There is tentative evidence supporting a familial basis for separation anxiety. The present study aimed to examine parent-child concordance for that subtype of anxiety. Fifty-four children diagnosed with anxiety disorders and their parents (54 mothers and 29 fathers) were recruited from two juvenile anxiety clinics. Sixty-three percent of children diagnosed with juvenile separation anxiety disorder had at least one parent who suffered from the putative adult variant of the disorder (odds ratio = 11.1) (P < 0.001). Affected parents reported high levels of separation anxiety in their own childhoods. Juvenile separation anxiety disorder in children was not associated with any other parental diagnosis. The small sample size and other potential biases caution against definitive conclusions being drawn, but the present data add to existing evidence that separation anxiety may aggregate in families.

Genetic and environmental influences on a measure of infant attachment security

A twin study of infant attachment security at age 24 months was conducted on archival data for a sample of 99 MZ pairs and 108 DZ pairs from the Louisville Twin Study. MZ concordance for attachment was 62.6%, which was significantly greater than the DZ concordance of 44.4%. Concordances were transformed into polychoric correlations, and LISREL was used to conduct a quantitative genetic analysis of the data. Results indicated that 25% of the variability in attachment was attributable to genetic factors, and the remaining 75% was attributable to non-shared environmental effects. No evidence was found for a contribution from shared environmental influences to attachment security. Possible concerns about the validity of twin methodology are addressed and various interpretations of the results are presented.

Genetic studies of panic disorder: a review

BACKGROUND

A review of the studies examining the genetic etiology of panic disorder shows the familial nature of the disorder and demonstrates that the etiology is greatly influenced by genetic factors. Strong evidence for vertical transmission in family studies led to molecular genetic studies, of which association designs appear promising, particularly when based on trait markers.

DATA SOURCES

The MEDLINE and PsycLIT databases were searched for all reports published between 1966 and 2000 containing the keywords panic, genetic, twin, adoption, linkage, association, and QTL.

CONCLUSION

We conclude that the multifactorial nature of panic disorder requires a multidisciplinary approach to gain insight into the determinants of the phenotype and the interaction of environmental and genetic factors.

The Virginia Twin Study of Adolescent Behavioral Development. Influences of age, sex, and impairment on rates of disorder

BACKGROUND

The Virginia Twin Study of Adolescent Behavioral Development is a cohort-longitudinal epidemiological study that uses the genetic twin design to study the development and maintenance of child psychiatric disorders. We determined the rates of DSM-III-R disorders, disorders with impairment, and age, sex, and comorbidity effects.

METHODS

Families of 2762 white twins aged 8 to 16 years participated. Twins and their parents were asked systematically about risk factors and current psychiatric symptoms by means of investigator-based psychiatric interviews and questionnaires. The DSM-III-R diagnoses were made for major depressive disorder, separation anxiety, overanxious disorder, simple phobia, social phobia, agoraphobia, oppositional defiant disorder, conduct disorder, and attention deficit hyperactivity disorder.

RESULTS

The 3-month point prevalence for any DSM-III-R disorders was 413 per 1000, and that for disorders with associated impairment was 142 per 1000. Emotional disorders with impairment occurred in 89 per 1000, with girls being more commonly affected; behavioral disorders had a prevalence of 71 per 1000, with boys being more frequently affected. The proportion with disorder who also had functional impairment varied across disorders; anxiety and phobic disorders were particularly likely not to be accompanied by impairment. Rates of emotional and behavioral disorders increased over the age range. There was extensive comorbidity among disorders.

CONCLUSIONS

The prevalence rates and patterns of findings from this study of twins are consistent with those of other epidemiological studies, supporting previous findings of few differences in rates of psychiatric disorder between twins and singletons. The importance of including measures of functional impairment is evident by its effect on rates of disorder and patterns of comorbidity.

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 influences in the determination of individual differences in self-reported symptoms of separation anxiety (SAD), overanxious disorder (OAD), and manifest anxiety (MANX) were evaluated in children and adolescents for three age groups (8-10, 11-13, and 14-16). Symptom counts for SAD and OAD were assessed for 1,412 twin pairs using the children's version of the Child and Adolescent Psychiatric Assessment, and MANX scores were based on child report from the Revised Children's Manifest Anxiety Scales. Despite significant age and gender differences in thresholds of liability for child reports of symptoms of SAD and OAD, additive genetic and environmental effects could be set equal across age and gender for these variables. For MANX, however, the best-fitting model was a common effects sex-limitation model with estimates of heritability varying dependent upon age and gender. Parameter estimates from the ACE models of OAD and SAD showed that additive genetic variation was a necessary component in the explanation of individual differences in child-reported symptoms of OAD (h2 = .37) across gender, but does not appear to be a major contributor to the explanation of individual differences in symptoms of SAD reported by children. Shared environmental effects (c2 = .40) were found to play a moderate role for SAD but could be dropped from the model for OAD and from all of the age groups for MANX, although the parameter approached significance among 11 yr to 13-year-old males.

Twin sibling differences in parental reports of ADHD, speech, reading and behaviour problems

Differences between twins and siblings in behaviour problems were investigated in a non-selected sample of 1938 families with children aged 4-12 years. Families were sent a questionnaire based on DSM-III-R criteria for Attention Deficit Hyperactivity Disorder (ADHD), Oppositional Defiant Disorder (ODD), Conduct Disorder (CD) and Separation Anxiety (SA), which was validated by formal clinical interview. The questionnaire also included measures of speech and reading problems. There were significant differences between twins and siblings for ADHD symptoms, but not for symptoms of ODD, CD or SA. Twins and siblings differed significantly for gestational age, birth weight, speech and reading problems. While there was little evidence for birth weight or gestational age contributing to the difference in ADHD symptoms, there was a strong association between ADHD symptoms and speech and reading problems.

Age at onset of panic disorder: influence of familial liability to the disease and of childhood separation anxiety disorder

OBJECTIVE

The authors investigated the relation of age at onset of panic disorder to liability to panic disorder and agoraphobia.

METHOD

Two hundred thirty-one outpatients with panic disorder were compared with 131 surgical outpatients on demographic variables and familial risk of psychiatric disorders. The distribution of patients' ages at onset of panic disorder and several covariates were entered in a stepwise survival analysis.

RESULTS

The patients with panic disorder had a significantly higher rate of childhood separation anxiety disorder and higher familial risks of panic disorder/panic disorder with agoraphobia and alcoholism. A family history of panic disorder with agoraphobia and the presence of childhood separation anxiety disorder influenced age at onset of panic disorder.

CONCLUSIONS

Age at onset of panic disorder may reflect genetic penetrance, and separation anxiety disorder may be an individual predictor of earlier onset of panic disorder.

Genetic factors in early separation anxiety: implications for the genesis of adult anxiety disorders

An important contemporary conceptualization of anxiety has suggested that heightened early separation anxiety is specifically associated with the risk of adult panic disorder, with hereditary factors underlying that cluster of anxiety disorders. Yet there is a dearth of studies examining whether early separation anxiety is inherited. The present twin study, based on a retrospective approach, revealed a substantial genetic contribution to separation anxiety in females but not in males, with unique environmental influences being important in both gender groups. Although speculative, an evolutionary explanation is offered to account for the apparent gender difference in the inheritance of early separation anxiety. It is hypothesized that, in some women, phylogenetic vestiges of separation anxiety may conflict with their need to compete in an individualistic manner in the modern workplace. Whether such an attachment-autonomy conflict accounts for the increased rate of panic disorder and agoraphobia in women is worthy of further study.

Adults who feared school: is early separation anxiety specific to the pathogenesis of panic disorder?

Although juvenile separation anxiety disorder is maintained to be a predisposing factor to adult panic disorder in DSM-III-R, past research has failed to clarify (a) whether it is separation anxiety per se or school refusal that is the pathogenic risk factor and (b) whether affected youngsters are specifically at risk of developing panic disorder rather than symptoms of general anxiety or phobias in later life. The present study of 74 adults who responded to media publicity found that a measure of early separation anxiety but not a history of school refusal was associated with risk of adult panic disorder according to DSM-III-R criteria. In contrast, separation anxiety scores were not associated with the presence or absence of general anxiety symptoms or phobic-avoidance in adulthood. Subjects with higher separation anxiety scores were more likely to have either a sibling or child with school refusal. Although the present study is limited in its method to mailed survey responses and, in part, to retrospective data, the results do provide additional support for Klein's influential separation anxiety theory of panic disorder.

The development of the Separation Anxiety Symptom Inventory (SASI)

Separation anxiety continues to be implicated as an early risk factor to adult emotional disorder but recent research findings are somewhat contradictory. Inconsistencies in approaches to measuring memories of early separation anxiety may have contributed to this lack of clarity. We report the development of a brief self-report instrument, the Separation Anxiety Symptom Inventory (SASI), which was designed to overcome some of these deficiencies in measurement. The SASI was shown to have a coherent factorial structure, high internal consistency (Cronbach's Alpha > .80) and test-retest reliability over an average of 24 months (Intraclass Correlation Coefficient = .89), with serial scores not being affected by changes in contemporaneous anxiety levels. Some index of the validity of the measure was achieved by (a) comparing SASI scores of index twins with descriptors of their "insecure" behaviours in early life provided by corresponding co-twins; (b) comparing SASI scores with retrospective DSM III-R diagnoses of early anxiety disorders obtained by structured interviews; and (c) examining SASI scores in subjects with histories of school refusal. The SASI provides a useful standardised measure which will aid in the further testing of the separation anxiety hypothesis of adult emotional disorder.

A controlled family history study of prepubertal major depressive disorder

First-degree (N = 195) and second-degree (N = 785) adult relatives of prepubertal children with major depression (N = 48), children with nonaffective psychiatric disorders (N = 20), and normal children (N = 27) were assessed by the Family History-Research Diagnostic Criteria method (FH-RDC), except for the adult informant (usually the mother), who was directly interviewed. Compared with normal controls, prepubertal children with major depressive disorder (MDD) had significantly higher familial rates of psychiatric disorders in both first- and second-degree relatives, especially MDD, alcoholism, and "other" (mostly anxiety) diagnoses. Relatives of children in the nonaffective psychiatric control (PC) group had low rates of alcoholism, high rates of other (anxiety) disorder diagnoses, and intermediate rates of MDD (accounted for by those children with separation anxiety). This suggests that prepubertal onset of major depression may be especially likely in families with a high aggregation of affective disorders when these families also have a high prevalence of alcoholism, and that a proportion of children without affective disorder but with separation anxiety disorder in this study were at high risk for the development of affective illness later in life. These results support the validity of prepubertal-onset depressive illness as a diagnostic category, and are consistent with high familial rates of MDD and other psychiatric disorders found in family studies of adolescent and early-onset adult probands with major affective disorders, and with studies of the offspring of parents with major affective disorders. Within the child MDD group substantial heterogeneity was found. Low familial rates of MDD were associated with suicidality and comorbid conduct disorder in the child probands. The highest familial rates of MDD, approximately threefold those in the normal controls, and all the bipolar relatives, were found in the families of prepubertal probands with MDD who never had a concrete suicidal plan or act and who were without comorbid conduct disorder. A useful nosological continuum in which to classify prepubertal MDD may be to place at one end those patients with comorbid conduct disorder and at the other end those patients with manifestations related to bipolarity, including hypomania, mania, and psychotic subtype.

Psychiatric illness in the mothers of anxious children

The authors compared maternal lifetime psychiatric illness for children with separation anxiety disorder and/or overanxious disorder (N = 58) and for children who were psychiatrically disturbed but did not manifest an anxiety or affective disorder (N = 15). The vast majority (83%) of mothers of children with separation anxiety disorder and/or overanxious disorder had a lifetime history of an anxiety disorder. Moreover, over one-half (57%) of the mothers presented with an anxiety disorder at the same time at which their children were seen for similar problems. Both of these rates significantly differed from those obtained for control subjects.

Searching for evidence on the validity of generalized anxiety disorder: psychopathology in children of anxious mothers

The diagnostic validity of generalized anxiety disorder (GAD) is tested by examining the relationship between GAD in mothers and children's overanxious disorder (OAD), separation anxiety (SA), and anxious symptoms in 331 mother-child dyads from a geographically based probability sample. Data on the relationship between mothers' major depressive disorder (MDD) and children's depression are presented for comparison. The National Institute of Mental Health (NIMH) Diagnostic Interview Schedule (DIS) was used in mothers and the NIMH Diagnostic Interview Schedule for Children (DISC), in children. Children of mothers with GAD were not at increased risk for OAD, SA, or anxious symptoms. In contrast, MDD in mothers conferred a risk for OAD in younger children and of MDD in older children. Additionally, older children of depressed mothers exhibited significantly more depressive symptoms. The presence of diffuse anxiety in children of mothers with MDD may represent a nonspecific response pattern in psychiatrically vulnerable children. Like GAD in adults, these anxiety symptoms in children may constitute a prodromal manifestation of other disorders and transient responses to life stressors.

Family histories of depressed and severely anxious children

Of 127 relatives of 12 anxious and 11 depressed children, 72% received Family History RDC diagnoses, most commonly depression and alcoholism. The family histories of the two groups were similar, suggesting that childhood depressive and anxiety disorders may be familially related.

Relationship between separation anxiety and panic and agoraphobic disorders

The paper addresses several issues pertinent to the characteristics and treatment of separation anxiety in children and adults. The rationale for separating separation anxiety from other childhood anxiety conditions rests on clinical observations of its relationship to panic disorder and its response to drug treatment. The psychopharmacological treatment of separation anxiety is reviewed, with special emphasis on the use of tricyclic antidepressants. The literature relevant to a possible association between separation anxiety and adult panic disorder is presented. The prevalence of separation anxiety disorder in adult outpatients with panic disorder is discussed. Data are presented to address the issue of treatment response in adult panic disorders with and without separation anxiety.