Parsing the Prospective Links from Externalizing and Internalizing Symptoms to Substance Use: A Systematic Review and Meta-Analysis

The purpose of this study was to systematically analyze the prospective relationships between externalizing and internalizing symptoms as predictors and subsequent substance use within the broadly-defined range of adolescence.

Previous reviews and studies have established robust links between early externalizing symptoms to later substance use, while evidence has been mixed when internalizing symptoms were examined as predictors.

The current systematic review synthesized 1,197 correlational effect sizes (620 for internalizing symptoms and 576 for externalizing symptoms) from 140 studies that met the inclusion criteria. Using a three-level meta-analytic regression model, aggregate effects for different types of internalizing and externalizing symptoms were obtained, and models including moderators such as age, gender, and type of substance use were examined. Findings indicated that higher levels of externalizing symptoms were moderately associated with more substance use, with conduct problems being the strongest predictor. Conversely, internalizing symptoms demonstrated weaker and less consistent links, with depressive symptoms showing the most significant, albeit still modest, relationship. Anxiety did not significantly predict substance use. These findings underscore the complex relationship between early symptoms and subsequent substance use and highlight the need for further research to better understand the mechanisms underlying these associations and to explore potential moderating factors.