Researchers have recognized the importance of developing an accurate classification system for externalizing disorders, though much of this work has been framed by a priori preferences for categorical vs. dimensional constructs. Newer statistical technologies now allow categorical and dimensional models of psychopathology to be compared empirically. In this study, we directly compared the fit of categorical and dimensional models of externalizing behaviors in a large and representative community sample of adolescents at two time points separated by nearly 2.5 years (N = 2027; mean age at Time 1 = 11.09 years; 50.8% female). Delinquent and aggressive behaviors were assessed with child and parent Child Behavior Checklist reports. Latent trait, latent class, and factor mixture models were fit to the data, and at both time points, the latent trait model provided the best fit to the data. The item parameters were inspected and interpreted, and it was determined that the items were differentially sensitive across all regions of the dimension. We conclude that classification models can be based on empirical evidence rather than a priori preferences, and while current classification systems conceptualize externalizing problems in terms of discrete groups, they can be better conceptualized as dimensions.
Psychologists, with their long-standing tradition of studying mechanistic processes, can make important contributions to further characterizing the risk associated with genes identified as influencing risk for psychiatric disorders. We report one such effort with respect to CHRM2, which codes for the cholinergic muscarinic 2 receptor and was of interest originally for its association with alcohol dependence. We tested for association between CHRM2 and prospectively measured externalizing behavior in a longitudinal, community-based sample of adolescents, as well as for moderation of this association by parental monitoring. We found evidence for an interaction in which the association between the genotype and externalizing behaviour was stronger in environments with lower parental monitoring. There was also suggestion of a crossover effect, in which the genotype associated with the highest levels of externalizing behavior under low parental monitoring had the lowest levels of externalizing behavior at the extreme high end of parental monitoring. The difficulties involved in distinguishing mechanisms of gene-environment interaction are discussed.
Objectives: A commonly encountered situation for evaluating clinicians is a history of significant problems in one setting with little or no difficulties in another. This study aims to describe this phenomenon and to examine its relations with other child and family characteristics. Method: A total of 1730 children (mean age 11.05 years) were studied from the first wave of the TRacking Adolescents Individual Lives Study (TRAILS), a large population-based study of Dutch youth. Parent and teacher ratings of aggression, rule breaking, inattention, and hyperactivity were obtained. Children were assigned to groups according to the presence of clinically relevant problems at home only, at school only, or in both settings. The rate of setting specific problems was calculated and comparisons between groups were made. Results: Setting specific, especially home specific, problems were quite common. Among children whom parents rated as having at least borderline-clinical problems, teachers reported clear or very clear behaviors at school at the following rates: aggression (22%), rule breaking (12.5%), inattention (55%), hyperactivity/impulsivity (33%). Compared to the school specific group, the home specific group contained a significantly higher percentage of girls with regard to inattention or hyperactivity and a significantly lower percentage of girls with regards to rule breaking. Logistic regression analyses revealed that home versus school specific problems were related to sex, child effortful control and parental stress. Conclusion: Externalizing problems are frequently encountered only in one setting between home and school and are related to sex, child effortful control, and parental stress.
Objective: To study the prospective relationship between maternal smoking during pregnancy (MSP) and behavioral problems, heavy alcohol use, daily smoking, and ever use of cannabis in the offspring and to assess the role of confounding and mediating factors in a systematic way. Methods: Population based cohort study of 2,230 respondents, starting in 2001 when respondents were around the age of 11 years, and two follow-up measurements at intervals of about 2.5 years (response rates of 96.0% and 81.4%). Results: Almost one third of the respondents’ mothers had smoked tobacco during pregnancy. These respondents were at an increased the risk for all outcomes except internalizing behavioral problems (significant odds ratios ranged from 1.40 to 2.97). The successive models showed that the potential confounding factors reduced the strength of all relationships. In the full model, the strongest relationship was found for mothers who smoked more than 10 cigarettes a day during pregnancy and daily smoking in early adolescence (odds ratio: 1.56), but none of the relationships was statistically significant. Conclusions: MSP is a marker for future behavioral outcomes in the offspring, but reducing the prevalence of MSP is unlikely to make a meaningful contribution to the prevention of these problems in adolescents.