Abstract
OBJECTIVE: The Incredible Years Series intervention has demonstrated efficacy for decreasing conduct disorder (CD) symptomatology in clinically affected youth in multiple randomized controlled trials. Because children with family psychiatric histories of antisocial behavior are at markedly increased risk for enduring symptoms of antisocial behavior (compared with their counterparts with a negative family history), the authors examined whether intervention effects across studies would prevail in that subgroup or would be relatively restricted to children without genetic risk. METHOD: A reanalysis was conducted of 5 randomized controlled trials of Incredible Years involving 280 clinically affected children 3 to 8 years of age for whom a family psychiatric history of externalizing behavior in first- and second-degree relatives was ascertained from at least 1 parent. RESULTS: Incredible Years equally benefitted children with CD with and without family psychiatric histories of externalizing behavior. Family psychiatric history of externalizing behavior and parental depressive symptomatology predicted greater severity of CD symptomatology at baseline. CONCLUSION: The beneficial effects of IY are evident in children with CD, irrespective of whether their conditions are more or less attributable to inherited susceptibility to enduring antisocial syndromes. A next phase of research should address whether earlier implementation of group-based education for parents of young children at increased familial risk for antisocial behavior syndromes-before the development of disruptive patterns of behavior-would result in even more pronounced effects and thereby constitute a cost-effective, targeted, preventive intervention for CD.