In this week's BMJ, Hutchings and colleagues report a randomised controlled trial1and a cost effectiveness analysis2 of a preventive intervention in parents of preschool children at risk of developing conduct disorder. The Incredible Years basic parenting programme was offered for 12 weeks in 11 socially disadvantaged Sure Start areas. The programme significantly improved antisocial behaviour as measured by the Eyberg child behaviour inventory (difference 4.4 points, 95% confidence interval 2.0 to 6.89, effect size 0.66). The cost was between £1300 (€1900; $2500) and £2000 per child,2 which is comparable to most psychological treatments and a fraction of the long term cost to society of untreated conduct disorder, which is 10 times that of controls.3 The study shows that effective community level prevention is possible using regular service staff if they are properly trained in an evidence based programme.

Conduct disorder is a major health and social problem. It is the most common psychiatric disorder in childhood, with a prevalence of around 5% across the world,4 5 which is rising.6 The diagnosis is given to children who display …