Examining income dynamics and externalizing and internalizing trajectories through a developmental psychopathology lens: A nationally representative study.

Prior research has documented elevations in levels of internalizing and externalizing behaviors among children in lower income families in comparison to more advantaged peers. However, most studies focus on behavior problems at a single point in time or within a short developmental period. Associations between income dynamics and developmental trajectories of behavior problems over time are less understood. To address this, the current study uses data from the National Longitudinal Study of Youth (N = 7,476; 50.8% male) to examine how income dynamics (annual income and income volatility) across three distinct developmental periods from early childhood to early adolescence relate to trajectories of externalizing and internalizing problems. Group-based mixture modeling revealed a five-group trajectory model for externalizing behavior and a four-group trajectory model for internalizing behavior. Higher cumulative annual income predicted greater likelihood of belonging to the low-stable group compared to the other, more problematic groups for both externalizing and internalizing trajectories. In addition, income losses predicted higher risk of membership in any group other than the low-stable group for internalizing and externalizing behavior. Developmental period-specific income dynamics, though not as consistent as cumulative dynamics, also predicted trajectory group membership.