Trajectories of boys' physical aggression, opposition, and hyperactivity on the path to physically violent and nonviolent juvenile delinquency

A semi-parametric mixture model was used with a sample of 1,037 boys assess ed repeatedly from 6 to 15 years of age to approximate a continuous distrib ution of developmental trajectories for three externalizing behaviors. Regr ession models were then used to determine which trajectories best predicted physically violent and nonviolent juvenile delinquency up to 17 years of a ge. Four developmental trajectories were identified for the physical aggres sion, opposition, and hyperactivity externalizing behavior dimensions: a ch ronic problem trajectory, a high level near-desister trajectory, a moderate level desister trajectory, and a no problem trajectory. Boys who followed a given trajectory for one type of externalizing problem behavior did not n ecessarily follow the same trajectory for the two other types of behavior p roblem. The different developmental trajectories of problem behavior also l ed to different types of juvenile delinquency. A chronic oppositional traje ctory, with the physical aggression and hyperactivity trajectories being he ld constant, led to covert delinquency (theft) only, while a chronic physic al aggression trajectory, with the oppositional and hyperactivity trajector ies being held constant, led to overt delinquency (physical violence) and t o the most serious delinquent acts.