Abstract
In the present study, we explore the utility of latent transition analysis to better understand the developmental course of youths' externalizing psychopathology using the Oregon ADHD-1000 data set. Symptomatic latent classes at each age (i.e., 9, 12, and 15 years) were identified, and the corresponding latent transition probabilities and most common latent transition pathways were described. Impairment was examined for clinical validation. The most notable findings included a group of youths with persistent inattention from childhood through adolescence, distinct from youths who decreased in hyperactivity/impulsivity (HI) with age, although HI persisted for some. Oppositional defiant disorder (ODD) occurred only alongside HI and was related to greater HI persistence. HI did not proceed later ODD; rather, HI and ODD were aligned in childhood and diverged slightly in adolescence. Collectively, with the present study's findings, we emphasize the importance of methods that allow for open exploration of which and how many symptoms are relevant at various points in development.