Examination of the association between internalizing and externalizing developmental trajectories and future substance use: A systematic review

Externalizing, internalizing, and combined developmental pathways to future substance use have been identified. Although evidence for the externalizing pathway seems robust, inconsistencies remain for the internalizing and combined pathways. This systematic review therefore aims to examine how trajectories of externalizing and internalizing problems, as well as their comorbidity, throughout childhood and adolescence influence the development of future substance use behaviors and problems. A systematic search was conducted across PsycINFO, MEDLINE, and Scopus for studies published between 2000 and 2024. Inclusion criteria included peer-reviewed longitudinal studies that examined the associations between trajectories of externalizing, internalizing, and co-occurring problems on future adolescent or adulthood substance use outcomes. Data extraction respected PRISMA guidelines. A total of 33 studies met inclusion criteria. Trajectories characterized by persistently high or increasing/adolescent onset levels of externalizing problems appear to be associated with a variety of different substance use outcomes in both adolescence and adulthood. Trajectories characterized by high or increasing levels of internalizing problems appear to be associated with some substance use outcomes in adulthood, with inconsistent results observed for adolescent outcomes. Inconsistent results are also observed for co-occurring trajectories. Given the developmental trends of these trajectories, early prevention and intervention efforts for externalizing and internalizing problems are needed to target later substance use.