title: Test of alternative hypotheses explaining the comorbidity between attention-deficit/hyperactivity disorder and conduct disorder.
abstract: There is significant comorbidity between attention-deficit/hyperactivity disorder (ADHD) and conduct disorder (CD). The conclusions of studies that examined the causes of comorbidity between ADHD and CD conflict, with some researchers finding support for the three independent disorders model and others finding support for the correlated risk factors model. We tested these models and eleven alternative hypotheses using the same analytical approach. The participants were 110 monozygotic twin pairs and 181 dizygotic twin pairs recruited from the Colorado Learning Disabilities Research Center Twin Study. The three independent disorders model did not fit the data, whereas the correlated risk factors model fit the data well. Several other comorbidity models fit the data as well as or better than the correlated risk factors model. The results suggest that correlated risk factors are a better explanation for the comorbidity between ADHD and CD than a third, independent ADHD+CD subtype.
authors.affiliation: Department of Psychology, University of Colorado, Boulder, CO 80309, USA. soo.rhee@colorado.edu
authors.forename: Soo Hyun
authors.initials: SH
authors.lastname: Rhee
authors.forename: Erik G
authors.initials: EG
authors.lastname: Willcutt
authors.forename: Christie A
authors.initials: CA
authors.lastname: Hartman
authors.forename: Bruce F
authors.initials: BF
authors.lastname: Pennington
authors.forename: John C
authors.initials: JC
authors.lastname: DeFries
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics; D015984:Causality; D002648:Child; D015897:Comorbidity; D019955:Conduct Disorder / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics / Q000523:psychology; D004200:Diseases in Twins / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics / Q000523:psychology; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics / Q000517:prevention & control; D006801:Humans; D007859:Learning Disabilities / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics / Q000523:psychology; D008297:Male; D015233:Models, Statistical; D010552:Personality Assessment; D012307:Risk Factors; D012931:Social Environment; D012963:Sociometric Techniques; D014429:Twins, Dizygotic / Q000235:genetics / Q000523:psychology; D014430:Twins, Monozygotic / Q000235:genetics / Q000523:psychology