Trajectories of internalizing problems across childhood: heterogeneity, external validity, and gender differences.

Developmental psychopathology theory speaks to the existence of early-manifesting internalizing problems with a heterogeneous longitudinal course. However, the course of internalizing problems has been investigated largely from late childhood onward, with methods that assume children's problem trajectories vary more so in rate than in qualitative functional form. This can obscure heterogeneity in symptom process and course, obscure onset of early gender differences in internalizing problems, and obscure the relevance of early sociocontextual risks for long-term internalizing outcomes. The present study addressed these issues by using person-oriented (latent growth mixture) methods to model heterogeneity in maternal-reported internalizing symptoms from age 2 to 11 years (N = 1,364). Three latent trajectory classes were supported for each gender: two-thirds of children followed a low-stable trajectory; smaller proportions followed decreasing/increasing or elevated-stable trajectories. Although the number, shape, and predictive validity of internalizing trajectory classes were similar across gender, trajectory classes' initial values and rates of change varied significantly across gender, as did the impact of maternal postpartum depression and anxiety on latent growth factors. Extracted latent trajectories were differentially predicted by postpartum maternal psychopathology, and themselves, in several respects, differentially predicted self-reported depressive symptoms in preadolescence. However, discussion focuses on the need for further external validation of extracted latent classes.