Skip to main content
×
Home
    • Aa
    • Aa

Sources of covariation among the child-externalizing disorders: informant effects and the shared environment

  • S. ALEXANDRA BURT (a1), MATT McGUE (a1), ROBERT F. KRUEGER (a1) and WILLIAM G. IACONO (a1)
Abstract

Background. Research has documented high levels of co-morbidity among childhood externalizing disorders, but its etiology remains in dispute. Specifically, although all behavior genetic studies of the etiology of the co-occurrence of attention deficit-hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), and conduct disorder (CD) agree that genetic factors are important, differences exist across studies in the relative weight assigned to genetic, shared environmental factors (i.e. factors that increase similarity among family members), and non-shared environmental factors (i.e. factors that decrease similarity among family members). Because heritability estimates can vary across informants, we used a biometric informant-effects model to determine whether these discrepancies were a function of systematic differences in maternal and child informant reports of ADHD, CD, and ODD.

Method. We studied 1782 11-year-old twins from the Minnesota Twin Family Study. Symptom counts for each disorder were obtained from interviews administered to twins and their mothers. We fit a model that allowed us to examine, both across and within informants, the genetic and environmental contributions to the co-occurrence among ADHD, CD, and ODD.

Results. The results revealed that the co-occurrence among the disorders common to maternal and child informant reports was influenced largely by shared environmental forces. Genetic factors also contributed, though their impact was only marginally significant. In contrast, the co-occurrence unique to each informant was influenced exclusively by either genetic or non-shared environmental factors.

Conclusions. Such findings offer additional evidence that shared environmental factors are important to the co-morbidity among ADHD, CD, and ODD, and highlight the necessity of considering informant effects when drawing conclusions about the origins of co-morbidity from analyses of genetically informative data.

Copyright
Corresponding author
Department of Psychology, Michigan State University, Psychology Building, East Lansing, MI 48824, USA. (Email: burts@msu.edu)
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Psychological Medicine
  • ISSN: 0033-2917
  • EISSN: 1469-8978
  • URL: /core/journals/psychological-medicine
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 18 *
Loading metrics...

Abstract views

Total abstract views: 80 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 30th May 2017. This data will be updated every 24 hours.