A Thapar1, R Harrington, P McGuffin. 1. Child and Adolescent Psychiatry Section, Department of Psychological Medicine, University of Wales College of Medicine, Cardiff, UK.
Abstract
BACKGROUND: Although attention-deficit hyperactivity disorder (ADHD) and conduct disorder (CD) frequently co-occur, the underlying mechanisms for this comorbidity are not well understood. AIMS: To examine whether ADHD and conduct problems share common risk factors and whether ADHD+CD is a more heritable variant of ADHD. METHOD: Questionnaires were sent to 2846 families. Parent-rated data were obtained for 2082 twin pairs and analysed using bivariate genetic analysis and a liability threshold model approach. RESULTS: The overlap of ADHD and conduct problems was explained by common genetic and non-shared environmental factors influencing both categories. Nevertheless, the two categories appeared to be partly distinct in that additional environmental factors influenced conduct problems. It appeared that ADHD+CD was a genetically more severe variant of ADHD. CONCLUSIONS: Conduct problems and ADHD share a common genetic aetiology; ADHD+CD appears to be a more severe subtype in terms of genetic loading as well as clinical severity.
BACKGROUND: Although attention-deficit hyperactivity disorder (ADHD) and conduct disorder (CD) frequently co-occur, the underlying mechanisms for this comorbidity are not well understood. AIMS: To examine whether ADHD and conduct problems share common risk factors and whether ADHD+CD is a more heritable variant of ADHD. METHOD: Questionnaires were sent to 2846 families. Parent-rated data were obtained for 2082 twin pairs and analysed using bivariate genetic analysis and a liability threshold model approach. RESULTS: The overlap of ADHD and conduct problems was explained by common genetic and non-shared environmental factors influencing both categories. Nevertheless, the two categories appeared to be partly distinct in that additional environmental factors influenced conduct problems. It appeared that ADHD+CD was a genetically more severe variant of ADHD. CONCLUSIONS: Conduct problems and ADHD share a common genetic aetiology; ADHD+CD appears to be a more severe subtype in terms of genetic loading as well as clinical severity.
Authors: Bernhard W Müller; Karla Gimbel; Anett Keller-Pliessnig; Gudrun Sartory; Markus Gastpar; Eugen Davids Journal: Eur Arch Psychiatry Clin Neurosci Date: 2007-01-02 Impact factor: 5.270
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Authors: H Christiansen; W Chen; R D Oades; P Asherson; E A Taylor; J Lasky-Su; K Zhou; T Banaschewski; C Buschgens; B Franke; I Gabriels; I Manor; R Marco; U C Müller; A Mulligan; L Psychogiou; N N J Rommelse; H Uebel; J Buitelaar; R P Ebstein; J Eisenberg; M Gill; A Miranda; F Mulas; H Roeyers; A Rothenberger; J A Sergeant; E J S Sonuga-Barke; H-C Steinhausen; M Thompson; S V Faraone Journal: J Neural Transm (Vienna) Date: 2008-01-16 Impact factor: 3.575