Psychological Medicine



Familial aggregation for conduct disorder symptomatology: the role of genes, marital discord and family adaptability


J. M. MEYER a1, M. RUTTER a1c1, J. L. SILBERG a1, H. H. MAES a1, E. SIMONOFF a1, L. L. SHILLADY a1, A. PICKLES a1, J. K. HEWITT a1 and L. J. EAVES a1c2
a1 Virginia Institute for Psychiatric and Behavioral Genetics, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, Institute of Behavioral Genetics, University of Colorado, Boulder, CO and Millennium Pharmaceuticals, Cambridge, MA, USA; MRC Child Psychiatry Unit and Social, Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry and Department of Child and Adolescent Psychiatry and Psychology, Guy's & St Thomas' School of Medicine, London, and School of Epidemiology and Health Science, Department of Medicine, University of Manchester

Abstract

Background. There is extensive evidence of statistical associations between family discord/maladaptation and antisocial behaviour in the children, but questions remain on the extent to which the psychopathological risks are genetically or environmentally mediated.

Methods. Twin pairs (N = 1350), aged 8 to 16 years, in the general population-based Virginia Twin Study of Adolescent Behavioral Development were assessed using the Child and Adolescent Psychiatric Assessment interview administered separately to both twins and both parents. Structured interviews for parental lifetime psychiatric disorders were also administered to the mothers and fathers. Maternal reports on Olsson's Family Adaptability and Cohesiveness questionnaire and the Dyadic Adjustment Scale were used as indices of the family environment. A path analytical model based on an extended twin-family design was used to test hypotheses about parent–offspring similarity for conduct disorder symptomatology.

Results. Family discord and maladaptation, which intercorrelated at 0·63, were associated with a roughly two-fold increase in risk for conduct disorder symptomatology. When parental conduct disorder was included in the model the environmental mediation effect for family maladaptation remained, but that for family discord was lost.

Conclusion. It is concluded that there is true environmental mediation from family maladaptation, operating as a shared effect, which accounts for 3·5% of the phenotypic variance. The assumptions underlying this genetic research strategy are made explicit, together with its strengths and limitations.


Correspondence:
c1 Social, Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, De Crespigny Park, London SE5 8AF, UK.
c2 Virginia Institute for Psychiatric and Behavioral Genetics, MCV-VCU, Box 980003, Richmond, VA 23298-0003, USA.


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