The co-occurrence between internalizing and externalizing behaviors

Abstract

Although Internalized and Externalized problem behaviors are described as separate phenomena at the psychometric and clinical levels, they frequently co-occur. Only few studies, however, have investigated the causes of such covariation. In a sample of 398 twin pairs aged 8-17 drawn from the general population-based Italian Twin Registry, we applied bivariate genetic analyses to parent-rated CBCL/6-18 Internalization and Externalization scores. Covariation of Internalizing and Externalizing problem behaviors was best explained by genetic and common environmental factors, while the influence of unique environmental factors upon covariance appeared negligible. Odds ratio values showed that a borderline/clinical level of Externalization is a robust predictor of co-existing Internalizing problems in the same child, or within a sibship. Our findings help to approximate individual risks (e.g., in clinical practice, predicting the presence of Internalization in an externalizing child, and vice-versa), and to recognize that several shared environmental and genetic factors can simultaneously affect a child's proneness to suffer from both types of problem behaviors.

Genetic and environmental influences upon the CBCL/6-18 DSM-oriented scales: similarities and differences across three different computational approaches and two age ranges

“…This study is based on the responses provided to the CBCL 6/18 by parents of children belonging in the Italian Twin Registry (ITR), a database including all possible twins in the Italian population [50], from which subjects aged 8-17 years, living in the industrialized province of Milan and in the suburban province of Lecco were sampled for psychometric studies of different nature and aims [35,36,49]. The recruitment methods and the socio-demographic characteristics are reported in detail elsewhere [36,49].…”

“…The recruitment methods and the socio-demographic characteristics are reported in detail elsewhere [36,49]. Briefly, 398 twin pairs were recruited; the participation rate of 56% did not differ between families living in the industrialized Milan province compared with those living in the suburban Lecco province [36,49]; the mean age of children and parents did not differ in the families who agreed, versus those who declined, participation into the study (respectively, 13.06 ± 2.60 vs. 13.11 ± 2.31, P = 0.62 for children; 46.06 ± 0.23 vs. 46.71 ± 0.35, P = 0.10 for mothers), and the maternal educational level and percentage of full-time employment were similar in participating and non-participating families (university degree: respectively, 17.7% vs. 16.3% of mothers, P = 0.65; mothers with full-time employment, respectively, 54 and 52%) [36,49], with figures that closely reflect the average of Italian north-western population [26] and suggest the sample's representativeness of the general population of this part of the country. Moreover, all CBCL mean scores of twins in this sample were similar to those found in a national probability sample [19], with the exception of Rule-Breaking Behaviour, which was significantly higher (1.6 vs. 1.3, P = 0.001), and Aggressive Behaviour, which was significantly lower (4.6 vs. 6.3, P = 0.001), than in the national sample [49].…”

“…The traditional scales of the CBCL have been used in a number of behavioural genetic studies in order to provide insight on the magnitude of genetic and environmental influences on psychopathology in childhood [6,25,36,42,54]. Recently, we have examined the aetiological influences on the CBCL DOS as defined by Achenbach and Rescorla [2] in twins belonging to the Italian Registry by quantitative ML approach; our results show that the phenotypic variance of the new DOS scales is explained by only additive genetic and unique environmental agents.…”

A Genetically Informed Study of the Covariation Between the CBCL/6-18 DSM-Oriented Problem Scales and the Competence Scales

“…The recruitment methods and the socio-demographic characteristics of participants are reported in detail elsewhere (Pesenti-Gritti et al 2008;Spatola et al 2007), and show that general factors such as the mean age of children and parents and the social and educational levels reflect population norms for Italy, without substantial differences between participants and non-participants in the psychometric survey. Moreover, the CBCL mean scores comprehensively reflect those found in a national probability sample (Frigerio et al 2004).…”

“…Edelbrock et al 1995;Hudziak et al 2000;Kuo et al 2004;Boomsma et al 2005;Pesenti-Gritti et al 2008) including the DOS (Spatola et al 2007), reporting both genetic and environmental influences of different size across different samples (estimates of heritability, shared environmental and unique environmental effects are in the range of 0.08-0.50, 0.25-0.68, and 0.23-0.45, respectively, for internalising problems and 0.00-0.71, 0.00-0.64, 0.26-0.36 for externalising problems). Such a variability of the parameter estimates could partially derive from the wide age range variation (from 7 to 17) across the different samples.…”