Dopamine transporter polymorphism associated with externalizing behavior problems in children

Early childhood externalizing behavior is a stable and heritable pattern of aggressive and delinquent behavior that often leads to the development of serious psychiatric disorders such as conduct disorder and attention deficit hyperactivity disorder. We examined the relationship between parent reported externalizing behavior (assessed at ages 4, 7, and 9 years) and the VNTR polymorphism of the 3' untranslated region of SLC6A3 (DAT1) in a community sample of 790 children ascertained as part of our longitudinal twin and adoption studies. We applied the sibling-based methodology developed by Fulker et al. [1999: Am J Hum Genet 64:259-267] for estimating allelic association with quantitative traits, while controlling for population stratification. An extension of these methods allowed for the inclusion of monozygotic twins, dizygotic twins, siblings, and singletons. We have demonstrated that the 9-repeat variant of the DAT1 is a significant risk allele for externalizing behavior at ages 4 (P=0.001) and 7 years (P=0.02). Although the effect size was negligible at age 9 (P=0.92), a formal test of the developmental decrease in effect across the three ages was non-significant (P=0.70).     

Multi-informant assessment of temperament in children with externalizing behavior problems.

We examined the criterion validity of parent and self-report versions of the Junior Temperament and Character Inventory (JTCI) in children with high levels of externalizing problems. The sample included 412 children (206 participants and 206 siblings) participating in a family study of attention and aggressive behavior problems. Criterion validity analyses included (a) correlations between temperament scales and emotional and behavioral scales and (b) correlations between temperament and intelligence and achievement scales. Temperament scales displayed strong convergent and discriminant validity. Across informants and samples, JTCI scales assessing novelty seeking and harm avoidance discriminated between internalizing and externalizing problems. Reward dependence, persistence, cooperativeness, and self-directedness displayed similar patterns of negative relations to emotional and behavioral scales and positive relations to intelligence, achievement, and competence.     

Cortisol and externalizing behavior in children and adolescents: mixed meta-analytic evidence for the inverse relation of basal cortisol and cortisol reactivity with externalizing behavior

An inverse relation between cortisol (re)activity and externalizing behavior has been hypothesized, but research findings seem equivocal. We tested this hypo(re)activity hypothesis in two meta-analyses, one for basal cortisol (k = 72 studies, N = 5,480) and one for cortisol reactivity to a stressor (k = 29 studies, N = 2,601). No association was found between cortisol reactivity and externalizing behaviors (r = -.04, 95% CI = -.11, .02). However, the relation between basal cortisol and externalizing behavior was significant but small (r = -.05, 95% CI = -.10, -.002). The age of the children significantly moderated this relation: Externalizing behavior was associated with higher basal cortisol (hyperactivity) in preschoolers (r = .09, 95% CI = .002, .17), and with lower basal cortisol (hypoactivity) in elementary school-aged children (r = -.14, 95% CI = -.19, -.08). There was no significant relation between cortisol and externalizing behavior in adolescents.     

Language for emotions in adolescents with externalizing and internalizing disorders

This study compared the structure and quality of emotion language in adolescents with externalizing disorders (N = 21), internalizing disorders (N = 18), and without a behavioral or emotional disorder (N = 16). Emotion language was elicited in response to vignette material prototypical for anger/sadness and fear, to autobiographical experiences, and to an actual emotional challenge. The findings reveal different emphases in the emotion language of internalizing and externalizing youth rather than a relative weakness for externalizing adolescents. Overall, clinical adolescents used fewer emotion terms that were semantically specific for anger, sad, or fear than typical adolescents. The results also show that emotion language is affected differentially for externalizing and internalizing adolescents depending on the emotion domain. Internalizing youth's emotion language to anger/sad events used inner-directed terms, situational references, and reduced intensity while their representation of emotions in response to salient threatening material was dominated by terms with a cognitive focus. Externalizing adolescents' emotion language responses to anger/sad events were more outer directed and intense, and their emotion language in a salient threat situation more orientated to direct affective terms. The results suggest that examining emotion language for specific emotion domains in adolescents with specific disorders will better clarify the role of emotion language in the regulation of emotions than approaches that globalize emotion language competencies or deficits.     

Internalizing and externalizing problem behavior in children with nocturnal and diurnal enuresis: a five-factor model perspective

OBJECTIVES: To describe personality traits, internalizing, and externalizing problems of 6- to 12-year-old children with nocturnal and diurnal enuresis, examining differences from healthy referents, and investigating the association between personality traits and problem behavior. METHODS: Eighty-five children with combined nocturnal and diurnal enuresis were compared with 56 children with nocturnal enuresis and 155 healthy children on personality characteristics and problem behavior. RESULTS: Post hoc analyses of multivariate analyses indicated that parents of children with combined nocturnal and diurnal enuresis reported on average lower conscientiousness and higher neuroticism scores in their children than parents of healthy children, although the magnitude of these differences was moderate. Considerable differences in mean scores were found for the Child Behavior Checklist (CBCL) total problem scale and moderate differences for internalizing, externalizing, and attention deficit hyperactivity disorder (ADHD) problems in children with nocturnal and diurnal enuresis compared with healthy referents. Regression analyses across enuretic and healthy groups demonstrated that personality trait and problem behavior scales share substantial variance. CONCLUSION: Moderate to substantially higher levels of problem behavior is demonstrated in children with nocturnal and diurnal enuresis, who also display slightly higher neuroticism and lower conscientiousness scores.     

Association between a marker for prenatal testosterone exposure and externalizing behavior problems in children

Prenatal androgen exposure has been associated with aggressive behavior in adults. It is less clear whether this association holds for childhood externalizing behavior. This study tests the hypothesis that increased prenatal androgen exposure is associated with aggressive behavior and attention problems in childhood. The ratio of the length of the second finger digit relative to the fourth digit, which is a marker for prenatal testosterone exposure, was assessed in 239 male and female fifth grade schoolchildren from Jintan, China, together with parent and teacher ratings of aggression and attention problems. Increased aggression and attention problems were both significantly associated with a lower ratio of the length of the second finger digit relative to the fourth digit ratios in boys but not girls. The effects remained significant after controlling for early adversity. These findings are the first to establish a relationship between an indirect indicator of fetal androgen exposure and any child psychopathology in Chinese children, and the observed effect size in boys was stronger than in male adults in Western studies. The results provide limited cross-cultural support for the importance of prenatal androgen exposure in contributing to the development of externalizing behavior problems in children, and they suggest that such effects may be specific to boys who may be relatively more vulnerable to early prenatal influences.     

Personality characteristics of the mothers of children with disruptive behavior disorders

The biological mothers of 100 outpatient children aged 6-13 years completed the Minnesota Multiphasic Personality Inventory (MMPI). Mothers of children given DSM-III diagnoses of conduct disorder (CD; n = 13) had significantly higher scores on MMPI scales associated with antisocial behavior (Pd and Ma), histrionic behavior (Hs and Hy), and disturbed adjustment (Sc). In contrast, the children's diagnosis of attention deficit disorder with hyperactivity (ADD/H; n = 22) was not significantly associated with any maternal MMPI elevations, and the CD x ADD/H interactions were not significant for any MMPI scale. These results indicate that CD is linked to maternal personality disorder, but ADD/H is not.     

Periadolescence: age-dependent behavior and psychopharmacological responsivity in rats

The behavior and psychopharmacological sensitivity of periadolescent rats are examined in this review. Periadolescent rats are hyperactive and engage in more conspecific play behavior than younger or older rats. When compared with other-aged rats, periadolescents exhibit enhanced performance in simple active-avoidance learning tasks, but perform poorly in more complex appetitive and avoidance learning tasks in which increases in locomotor activity do not improve performance, perhaps as a result of age-specific alterations in selective attention or stimulus processing. Such behavioral "anomalies" of periadolescent animals observed in traditional laboratory situations may be in some way adaptive when considered in the context of the animals' natural habitat. In terms of psychopharmacological responsiveness, periadolescent rats, when compared with younger or older animals, are less sensitive to catecholaminergic agonists but are more responsive to the catecholaminergic antagonist haloperidol. This pattern of psychopharmacological sensitivity suggests that the catecholaminergic systems may be temporarily hyposensitive during the periadolescent period. Evidence is presented that a negative feedback system in the form of dopamine autoreceptors may become functionally mature in mesolimbic brain regions during the periadolescent period. The possibility is presented that maturation of these self-inhibitory autoreceptors might result in a temporary decrease in the efficacy of mesolimbic dopamine projections, perhaps contributing to the psychopharmacological and behavioral characteristics of periadolescent animals. In support of this suggestion, evidence is reviewed indicating that the behavior of adult animals with lesions of the ventral tegmental area, a region containing cell bodies from which these mesolimbic dopaminergic projections originate, resembles that of periadolescent rats.     

Response decision processes and externalizing behavior problems in adolescents

Externalizing behavior problems of 124 adolescents were assessed across Grades 7-11. In Grade 9, participants were also assessed across social-cognitive domains after imagining themselves as the object of provocations portrayed in six videotaped vignettes. Participants responded to vignette-based questions representing multiple processes of the response decision step of social information processing. Phase 1 of our investigation supported a two-factor model of the response evaluation process of response decision (response valuation and outcome expectancy). Phase 2 showed significant relations between the set of these response decision processes, as well as response selection, measured in Grade 9 and (a) externalizing behavior in Grade 9 and (b) externalizing behavior in Grades 10-11, even after controlling externalizing behavior in Grades 7-8. These findings suggest that on-line behavioral judgments about aggression play a crucial role in the maintenance and growth of aggressive response tendencies in adolescence.     

Low salivary cortisol levels and externalizing behavior problems in youth

Research linking basal cortisol levels with internalizing and externalizing behavior problems in youths has yielded inconsistent results. We hypothesize that the high moment to moment variation in adrenocortical activity requires an analytical strategy that separates variance in cortisol levels attributable to "stable traitlike" versus "state or situationally specific" sources. Early morning saliva samples were obtained from 724 youths (M age = 13.5 years; range = 6-16 years in Year 1) on 2 successive days 1 year apart. Latent state-trait modeling revealed that 70% of the variance in cortisol levels could be attributed to statelike sources, and 28% to traitlike sources. For boys only, higher levels of externalizing problem behaviors were consistently associated with lower cortisol attributable to traitlike sources across 3 years of behavioral assessment. The inverse association between individual differences in cortisol and externalizing problem behavior has previously only been reported in studies of at-risk or clinical groups. The present findings suggest the relationship is a stable phenomenon that spans both normative and atypical child development. Studies are needed to reveal the biosocial mechanisms involved in the establishment and maintenance of this phenomenon, and to decipher whether individual differences in this hormone-behavior link confers risk or resilience.     

Cultural issues in the treatment of young African American children diagnosed with disruptive behavior disorders

OBJECTIVE: To discuss issues relevant to treating young African American children with disruptive behavior disorders. METHOD: We treat behavior disorders, correlates of behavior disorders, and special differences between African American and Caucasian children that could lead to or explain behavior problems. DISCUSSION: The majority of the information on young children diagnosed with disruptive behavior disorders has been obtained primarily from Caucasian children and families. Unfortunately, this reliance on Caucasian data neglects the unique needs of minorities and may lessen the quality of the services that they receive. Omission of ethnic concerns becomes even more salient with the increasing ethnic diversity among children and families in the United States. CONCLUSIONS: We suggest future research and clinical directions that will ultimately assist clinicians to provide high-quality mental health services to African American children.     

Disorganized attachment representation and atypical parenting in young school age children with externalizing disorder

We investigated the relationship of child attachment representation, psychopathology, and maternal atypical parenting in a high risk sample. Sixty-one consecutive clinical referrals with externalizing disorder aged 4 - 9 years were assessed for attachment representations measured with Manchester Child Attachment Story Task (MCAST), atypical parental expressed emotion (EE), maternal mood, and parent and teacher ratings of child behaviour. Disorganized attachment representations were found in 58% of cases, independent of ADHD symptoms. Pervasive disorganization was associated with very high maternal EE. Attachment status, maternal depression, and ADHD diagnosis were independently associated with parent-rated child behaviour problems; teacher ratings were associated with child's age and ADHD status. Disorganized attachment shows a high prevalence and independent associations with attention deficit symptomatology and maternal EE.     

Genes mediate the association between P3 amplitude and externalizing disorders

Reduced P3 amplitude has been consistently linked to a spectrum of externalizing disorders. Utilizing data from a large sample of adolescent male twins (N=1196), we used biometric modeling to assess the genetic and environmental contributions to the association between reduced P3 amplitude and a general vulnerability to externalizing disorders. Externalizing vulnerability was indexed by a composite of symptoms of conduct disorder, adult antisocial behavior, and alcohol, nicotine, and drug dependence. The sample included two independent age cohorts, providing an internal replication of the findings. For the best-fitting model, genetic influences alone accounted for the association between P3 amplitude and externalizing disorders, with an estimated genetic correlation of r(g)=-.22. Results replicated across the two age cohorts and demonstrate that reduced P3 amplitude is a marker of the biological vulnerability to externalizing disorders.     

Short-term growth in children with growth disorders

Objective : We have previously demonstrated that normal prepubertal growth over 1 year is composed of growth spurts lasting an average of 8 weeks, separated by periods of very slow growth or stasis. We have now analysed short-term growth patterns in eight children with different growth disorders: Turner syndrome ( n = 2), intrauterine growth retardation (IUGR, n = 1) and growth hormone (GH) deficiency (GHD, n = 5). Methodology : Height was measured daily in the morning by parents over 4-12 months. Regression and time series analysis were used to characterize short-term growth. In two boys (GHD and IUGR) their normal twin brother was measured in parallel. Results : All height velocity curves, based on regression analysis, showed a biphasic pattern, characterized by growth spurts of varying amplitudes and periods of very slow growth or growth stasis. When compared to growth curves in normal children, the principal qualitative differences in GHD and Turner syndrome were increased stasis time and reduced growth spurt amplitude. In IUGR reduced amplitude and length of growth spurts were seen, but the time spent in stasis was similar to normal children. Two naive patients with GHD increased the amplitude of their growth spurts by a mean 0.013 cm day -1 on GH treatment, with the mean length of their growth spurts increasing by 10 days. Their time spent in stasis decreased from 19% to 6% on GH. In two subjects with GHD the growth pattern during maintenance GH treatment was similar to that seen in normal children. Using time series analysis significant periodicities in height measurements were seen in the majority of children with growth disorders, which disappeared in patients with GHD in the catch-up phase after commencing GH therapy. Conclusions : (1) The growth spurts and stases seen in normal children are also observed in those with growth disorders, (2) different growth disorders have variable effects on the spurt-stasis model of childhood growth, (3) catch-up growth on GH in children with GHD was achieved by increasing the amplitude of the growth spurts and reducing the time spent in stasis.     

Autonomic activity in boys with disruptive behavior disorders

Skin conductance (SC) and heart rate (HR) were measured during rest, a series of tones, and a reaction time task in 34 boys with disruptive behavior disorder to ascertain (a) if this broadly defined group differed from control boys (n= 33) and (b) if there were differences within the spectrum related to component diagnoses or to target behaviors. Disruptive boys had higher resting HR than controls, due largely to those without a subdiagnosis of conduct disorder. Disruptive boys showed a smaller increment in SC response frequency for task instructions. They did not show a general deficit in phasic SC reactivity but habituated to signal stimuli at a faster rate than did controls. However, their SC response latencies were shorter despite slower motor reaction time. Responsivity variables were similar in boys with and without a subdiagnosis of conduct disorder. The data are not compatible with the hypothesis of low autonomic nervous system (ANS) baselines in disruptive boys but partially suggest low ANS reactivity. They generally support the validity of the disruptive behavior disorder spectrum. Correlations with measures of aggression and impulsivity suggest that individual differences within the spectrum might be more fruitfully described by behavior dimensions than by conventional subdiagnoses.     

Short-term growth in children with growth disorders

OBJECTIVE: We have previously demonstrated that normal prepubertal growth over 1 year is composed of growth spurts lasting an average of 8 weeks, separated by periods of very slow growth or stasis. We have now analysed short-term growth patterns in eight children with different growth disorders: Turner syndrome (n = 2), intrauterine growth retardation (IUGR, n = 1) and growth hormone (GH) deficiency (GHD, n = 5). METHODOLGY: Height was measured daily in the morning by parents over 4-12 months. Regression and time series analysis were used to characterize short-term growth. In two boys (GHD and IUGR) their normal twin brother was measured in parallel. RESULTS: All height velocity curves, based on regression analysis, showed a biphasic pattern, characterized by growth spurts of varying amplitudes and periods of very slow growth or growth stasis. When compared to growth curves in normal children, the principal qualitative differences in GHD and Turner syndrome were increased stasis time and reduced growth spurt amplitude. In IUGR reduced amplitude and length of growth spurts were seen, but the time spent in stasis was similar to normal children. Two naive patients with GHD increased the amplitude of their growth spurts by a mean 0.013 cm day(-1) on GH treatment, with the mean length of their growth spurts increasing by 10 days. Their time spent in stasis decreased from 19% to 6% on GH. In two subjects with GHD the growth pattern during maintenance GH treatment was similar to that seen in normal children. Using time series analysis significant periodicities in height measurements were seen in the majority of children with growth disorders, which disappeared in patients with GHD in the catch-up phase after commencing GH therapy. CONCLUSIONS: (1) The growth spurts and stases seen in normal children are also observed in those with growth disorders, (2) different growth disorders have variable effects on the spurt stasis model of childhood growth, (3) catch-up growth on GH in children with GHD was achieved by increasing the amplitude of the growth spurts and reducing the time spent in stasis.