Background: This study investigated the early processes involved in the development of symptoms of conduct disorder and hyperactivity.
Method: The study employed a prospective design, over a period from 2 months to 8 years. Detailed observational data of early and later mother–child interactions were collected, infant prefrontal function (the A not B task) was assessed, and symptoms of child conduct disorder and hyperactivity were rated by maternal report at age 5 and 8 years.
Results: The principal findings of the study were that emotional dysregulation on the A not B task at 9 months predicted symptoms of conduct disorder at 5 and 8 years, and delayed object reaching times on the same task predicted hyperactive symptoms at 5 years. These two developmental trajectories were associated with distinct patterns of early parenting that were strongly influenced by infant gender. Thus, in boys early emotional dysregulation was predicted by rejecting and coercive parenting, and delayed reaching on the A not B task by coercive parenting, whereas in girls only continuity from earlier infant behaviour could be demonstrated. There was strong continuity between these early infant behaviours and later child disturbance that was partially mediated by parenting for conduct disorder symptoms (maternal hostile parenting in boys, and maternal coercive parenting in girls), but not for hyperactive symptoms.
Conclusions: These data would suggest that only in boys was there evidence for the existence of a sensitive period for the development of hyperactive symptoms, and to a lesser extent, conduct disorder symptoms.