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The etiologic role of genetic and environmental factors on disordered eating was examined in a sample of 15- to 17-year-old female-female, male-male, and opposite-sex twin pairs. Also assessed was whether a single factor is underlying 3 facets (body dissatisfaction, drive for thinness, bulimia) of disordered eating, including the possible importance of sex differences. Univariate model-fitting analyses indicated that genetic factors are more important for girls and environment more important for boys for body dissatisfaction and drive for thinness. A multivariate common factor analysis indicated that a single factor accounted for the association among these 3 facets of disordered eating in both sexes. However, only 50% of the genetic risk for this factor is shared between the sexes. Keywords: eating disorder, disordered eating, twin study, genetics, sex differences

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.addbeh.2006.03.047 Byline: Michael C. Neale, Steven H. Aggen, Hermine H. Maes, Thomas S. Kubarych, J. Eric Schmitt Keywords: Substance use abuse dependence; Factor analysis; Latent class analysis; Factor mixture models; Item response theory; Twins; Relatives; Contingent response data; Skip pattern; Missing data; Misuse Abstract: The measurement of behavior is inherently problematic, and this is especially true of substance use and abuse phenotypes. The contingent nature of many assessments, such that symptoms of abuse and dependence cannot be obtained from those who have not initiated substance use, presents special difficulties. Furthermore, it is not clear whether individual differences in liability to use, abuse and dependence are best characterized as dimensions or classes or a combination of both. This article outlines research designs and methods suitable for quantifying liability to substance use. The value of data collected from relatives is emphasized in this context, as they permit identification of models normally compromised because data on, e.g., substance dependence symptoms, are systematically missing in those who have not initiated use of the substance in question. Author Affiliation: Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Box 980126, Richmond, VA 23298-0126, USA

This study used three instruments to assess genetic and phenotypic interrelationships related to symptoms of attention deficit hyperactivity disorder in same-sex twins. Findings indicate that behavioral symptoms like inattentiveness, impulsivity, and restlessness were strongly correlated across measures and that genetic modelling confirmed behavioral contrast effects between twins.

ABSTRACT. Objective: This study reports prevalences of lifetime and current alcohol, tobacco and drug use in adolescents; examines associations between substance use and a number of putative risk factors; and [...]

The impact of genetic and environmental factors on behavioral problems was investigated by the Virginia Twin Study of Adolescent Behavioral Development in a sample of Caucasian twins aged 8-16 years. Results showed that monozygotic (MZ) twins correlated more highly than dizygotic (DZ) twins. DZ variances were greater than MZ variances and DZ correlations were low for measures of attention deficit hyperactivity disorder (ADHD). Measures of oppositional behavior and conduct disorder showed shared environmental effects.

Various issues concerned with the assessment of substance use and abuse phenotypes are outlined.

The conduct disorder, of children belonging to intact families, is compared with children from stepfather families, with alcoholism as a prevailing factor. This study explains the way divorce affects the children and is the main cause of adolescent problems.

The relationship between parental psychiatric disorders and children's psychiatric symptoms are assessed using a sample of 850 twin families. Symptoms of depression and over anxious disorder are related to parental depression, with maternal depression causing higher risks.