Abstract
Evidence of internalizing (INT)-to-externalizing (EXT) directional effects (e.g., acting out/masked depression hypotheses) has been commonly found in older youth. However, this relationship may still be present but fluctuate more dynamically during early development, a period of significant cognitive and self-regulatory changes. Moreover, dynamic codevelopment has not been well studied in samples at elevated risk, including those due to prenatal cocaine exposure. There is some evidence that prenatal cocaine exposure increases risk for EXT, but findings have been mixed. One possible explanation may be that INT may codevelop with EXT in higher-risk contexts, and most studies do not consider codevelopment of these problems. We utilized time-varying effect modeling to investigate the age-varying effect of INT on concurrent EXT across early childhood (1.5-6.5 years) and whether associations varied as a function of sex and prenatal cocaine exposure. The sample was primarily low-income and Black (N = 198; 49% males; 74% Black; 71% receiving federal assistance), oversampled for prenatal cocaine exposure using a case-control design. Results identified the strongest regression effect of INT on EXT during the toddlerhood/preschool period (2.5-4.5 years), especially for male children. No differences were observed by cocaine exposure. Findings suggest that INT problems are most strongly associated with increased EXT difficulties at earlier ages, which may be a sensitive period during which targeting INT may potentially prevent long-term co-occurring problems.