Serena Bezdjian

Genetic and environmental influences on impulsivity: A meta-analysis of twin, family and adoption studies

A meta-analysis of twin, family and adoption studies was conducted to estimate the magnitude of genetic and environmental influences on impulsivity. The best fitting model for 41 key studies (58 independent samples from 14 month old infants to adults; N=27,147) included equal proportions of variance due to genetic (0.50) and non-shared environmental (0.50) influences, with genetic effects being both additive (0.38) and non-additive (0.12). Shared environmental effects were unimportant in explaining individual differences in impulsivity. Age, sex, and study design (twin vs. adoption) were all significant moderators of the magnitude of genetic and environmental influences on impulsivity. The relative contribution of genetic effects (broad sense heritability) and unique environmental effects were also found to be important throughout development from childhood to adulthood. Total genetic effects were found to be important for all ages, but appeared to be strongest in children. Analyses also demonstrated that genetic effects appeared to be stronger in males than in females. Method of assessment (laboratory tasks vs. questionnaires), however, was not a significant moderator of the genetic and environmental influences on impulsivity. These results provide a structured synthesis of existing behavior genetic studies on impulsivity by providing a clearer understanding of the relative genetic and environmental contributions in impulsive traits through various stages of development.

Assessing Inattention and Impulsivity in Children during the Go/NoGo Task.

Behavioural performance in the Go/NoGo task was compared with caregiver and teacher reports of inattention and hyperactivity-impulsivity in 1,151 children (N = 557 boys; N = 594 girls) age 9- 10-years-old. Errors of commission (NoGo errors) were significantly correlated with symptom counts of hyperactivity-impulsivity, while errors of omission (Go errors) were significantly correlated with symptom counts for inattention in both caregiver and teacher reports. Cross-correlations were also evident, however, such that errors of commission were related to inattention symptoms, and errors of omission were related to hyperactivity-impulsivity. Moreover, hyperactivity-impulsivity and inattention symptoms were highly intercorrelated in both caregiver (r = .52) and teacher reports (r = .70), while errors of commission and omission were virtually uncorrelated in the Go/NoGo task (r = .06). The results highlight the difficulty in disentangling hyperactivity-impulsivity and inattention in questionnaires, and suggest that these constructs may be more clearly distinguished in laboratory measures such as the Go/NoGo task.

Psychopathic personality in children: genetic and environmental contributions

BACKGROUND The current study investigates whether the underlying factor structure of psychopathic personality traits found in adults is similar to that in children and what the extent of the genetic and environmental influences are on these psychopathic traits. METHOD Psychopathic personality traits were assessed in a community sample of 1219 twins and triplets (age 9-10 years) through caregiver reports of each childs behavior using the Child Psychopathy Scale (CPS). RESULTS Confirmatory factor analyses revealed an optimal two-factor solution (callous/disinhibited and manipulative/deceitful) to the CPS subscales. Bivariate genetic modeling of the two computed factor scores revealed significant genetic as well as unique environmental influences on psychopathic personality traits in both boys and girls, with heritability estimates of 0.64 and 0.46, respectively, in boys and 0.49 and 0.58, respectively, in girls. No shared environmental influences on psychopathic personality traits were found. CONCLUSIONS The relationship between the two factors was mediated by both genetic and unique environmental factors common to both traits.

The genetic and environmental covariation among psychopathic personality traits, and reactive and proactive aggression in childhood.

The present study investigated the genetic and environmental covariance between psychopathic personality traits with reactive and proactive aggression in 9- to 10-year-old twins (N = 1,219). Psychopathic personality traits were assessed with the Child Psychopathy Scale (D. R. Lynam, 1997), while aggressive behaviors were assessed using the Reactive Proactive Questionnaire (A. Raine et al., 2006). Significant common genetic influences were found to be shared by psychopathic personality traits and aggressive behaviors using both caregiver (mainly mother) and child self-reports. Significant genetic and nonshared environmental influences specific to psychopathic personality traits and reactive and proactive aggression were also found, suggesting etiological independence among these phenotypes. Additionally, the genetic relation between psychopathic personality traits and aggression was significantly stronger for proactive than reactive aggression when using child self-reports.

Sex-specific association between psychopathic traits and electrodermal reactivity in children.

This study investigated the relationship of skin conductance response (SCR) to a child psychopathy measure. Blunted electrodermal activity is a theoretically important characteristic of psychopathy, but it has not been fully explored in preadolescents or females. The authors tested the hypothesis that reduced SCR magnitude is associated with psychopathic-like traits in boys and girls. Participants were drawn from an ethnically diverse community sample of 9- to 10-year-old twins. Given the fact that members of each twin pair were rated by the same individual (i.e., their caregiver) on the Child Psychopathy Scale, the authors examined individual differences at the within-family level. Skin conductance data were collected during a passive auditory task consisting of 75-dB tones as well as miscellaneous sounds (e.g., baby cries, bird noises, and speech-like stimuli). Reduced SCR magnitude (hyporeactivity) was characteristic only of boys with higher psychopathy scores. More specifically, electrodermal hyporeactivity was linked to the interpersonal facet of psychopathy, suggesting that it is a biological marker of a manipulative and deceitful orientation in males. No association was found between SCRs and psychopathic traits in girls, indicating the importance of sex specific etiologies of psychopathy in childhood.

Brief Report: Interaction between social class and risky decision-making in children with psychopathic tendencies.

OBJECTIVE Adult psychopaths are thought to have risky decision-making and behavioral disinhibition, but little is known about the moderating effects of psychosocial factors and whether these associations can be observed in children with psychopathic tendencies. This study tests the biosocial hypothesis that social class will moderate psychopathy-neurocognition relationships, with these effects being stronger in children from high social classes. METHOD Preadolescent community twins (N=298) were assessed on decision-making (Iowa Gambling) and behavior inhibition (Porteus Maze) tasks, while psychopathic tendencies and socioeconomic status were assessed by the childs caregiver. RESULTS A significant interaction was observed whereby risky decision-making was associated with psychopathic tendencies only in children from benign home environments. CONCLUSIONS Findings support a biosocial interaction perspective on child psychopathy, suggesting that risky decision-making may particularly predispose to psychopathic traits in children from benign home backgrounds.

Genetic and Environmental Influences on the Junior Temperament and Character Inventory in a Preadolescent Twin Sample

This study evaluated the genetic and environmental structure of personality variables from the Junior Temperament and Character Inventory (JTCI), in 605 pairs of 9- and 10-year old twins. There is a paucity of information on the biometric structure of temperament and character traits in preadolescent children. Latent factor models were fit to the subscales/items of each trait as a method of estimating genetic and environmental effects on true score variance, especially since internal consistency and reliability were moderate or low for some scales (particularly Reward Dependence and Persistence). Shared environmental influences on Cooperativeness were substantial. Significant heritability estimates were obtained for Self-directedness and Harm Avoidance, but not Novelty Seeking, Reward Dependence or Persistence. With the exception of Harm Avoidance, each of the scales failed to show measurement invariance with respect to sex, suggesting these scales may differ in meaning for boys and girls at this age.

The heritability of psychopathic personality in 14- to 15-year-old twins: a multirater, multimeasure approach.

Until now, no study has examined the genetic and environmental influences on psychopathic personality across different raters and method of assessment. Participants were part of a community sample of male and female twins born between 1990 and 1995. The Child Psychopathy Scale and the Antisocial Process Screening Device were administered to the twins and their parents when the twins were 14-15 years old. The Psychopathy Checklist: Youth Version (PCL:YV) was administered and scored by trained testers. Results showed that a 1-factor common pathway model was the best fit for the data. Genetic influences explained 69% of the variance in the latent psychopathic personality factor, while nonshared environmental influences explained 31%. Measurement-specific genetic effects accounted for between 9% and 35% of the total variance in each of the measures, except for PCL:YV, where all genetic influences were in common with the other measures. Measure-specific nonshared environmental influences were found for all measures, explaining between 17% and 56% of the variance. These findings provide further evidence of the heritability in psychopathic personality among adolescents, although these effects vary across the ways in which these traits are measured, in terms of both informant and instrument used.

The structure of DSM-IV ADHD, ODD, and CD criteria in adolescent boys: A hierarchical approach

Numerous studies have examined the structure of the childhood externalizing disorder symptoms of Attention Deficit Hyperactivity Disorder (ADHD), Oppositional Defiant Disorder (ODD), and Conduct Disorder (CD), both separately as well as simultaneously. The present study expanded on previous findings by implementing a multi-level hierarchical approach to investigating the component structure of ADHD, ODD, and CD criteria in 487 14-year-old boys from the Minnesota Twin Family Study (MTFS). We found support for a hierarchical conceptualization of externalizing behavior criteria in early adolescent boys by specifying how one-, two-, three-, four-, five- and six-factor models of externalizing criteria can be integrated. These results suggest that it may be more beneficial to conceptualize different levels of this hierarchy as relevant to different issues in case conceptualization and research design, from the broad level of an overall externalizing spectrum, to the level of finer-grained subtypes within specific disorders.

Resilience in the United States Air Force: Psychometric Properties of the Connor-Davidson Resilience Scale (CD-RISC).

Results are presented for the largest study (N = 53,692) ever conducted on the 25-item Connor-Davidson Resilience Scale (CD-RISC), a popular measure of resilience. We examined the internal consistency of the CD-RISC items and associated mean resilience levels within a sample of enlisted basic trainees in the United States Air Force. In addition, the predictive validity of the CD-RISC Total Score was examined for real-life military outcomes, including attrition from service and mental health diagnosis. The CD-RISC items demonstrated strong internal consistency. Item-level examinations of scores revealed that most trainees reported relatively high resilience. Results indicated that resilience measured at the beginning of military service is a significant predictor of (a) attrition from service and (b) obtaining a mental health diagnosis within 6 months of entry. Implications and future directions are discussed.