The Role of Early Language Difficulties in the Trajectories of Conduct Problems Across Childhood.

This study uses latent growth curve modelling to contrast the developmental trajectories of conduct problems across childhood for children with early language difficulties (LD) and those with typical language (TL). It also examines whether the presence of early language difficulties moderates the influence of child, parent and peers factors known to be associated with the development of conduct problems. Unconditional and language status conditional latent growth curves of conduct problems were estimated for a nationally representative cohort of children, comprising of 1627 boys (280 LD) and 1609 girls (159 LD) measured at ages 4-5, 6-7, 8-9 and 10-11. Multiple regression tested interaction between language status and predictors of the level and slope of the development of conduct symptoms. On average, children's conduct problems followed a curvilinear decrease. Compared to their TL peers, LD boys and girls had trajectories of conduct problems that had the same shape but with persistently higher levels. Among boys, LD amplified the contributions of parental hostility and SES and protected against the contributions of sociability and maternal psychological distress to a high level of conduct problems. In low SES boys, LD was a vulnerability to a slower rate of decline in conduct problems. Among girls, LD amplified the contributions of low pro-social behaviour to a higher level and sociability to a slower rate of decline of conduct problems while dampening the contribution of peer problems to a higher level of problems.