Positive affect as a developmental mediator of early adversity and internalizing psychopathology

BACKGROUND: Early life adversities (ELAs) including experiences such as abuse, neglect, and household dysfunction are strongly linked to psychopathology; yet, the developmental pathways connecting ELA to externalizing and internalizing psychopathology remain unclear. While most research has focused on threat and negative affect, positive emotions may represent a critical but understudied mechanism linking ELA to mental health outcomes. METHODS: Using data from the Adolescent Brain Cognitive Development (ABCD) study, we examined positive affect trajectories across six timepoints spanning childhood through adolescence (ages 9-10 to 12-13). We employed person-centered trajectory-based clustering to identify distinct patterns in positive affect - independent of ELA exposure - followed by multinomial logistic regression to examine associations between cumulative ELA exposure and trajectory membership. Mediation analyses tested whether positive affect trajectories explained links between ELA and psychopathology outcomes. RESULTS: Four distinct positive affect trajectories emerged: High-Stable, Declining, Persistently Low, and Volatile (N = 7,457). Higher ELA scores significantly predicted membership in all non-high-stable trajectories, with the strongest association existing for the Persistently Low group (β = .321, p < .001). Mediation analyses revealed that Persistently Low trajectory group membership significantly mediated the relationship between ELA and internalizing problems (indirect effect = 0.030, 95% CI [0.012, 0.056], p = .007), but not externalizing problems (N = 3,927). CONCLUSIONS: This study demonstrates that ELA shapes positive affect development through distinct, heterogeneous pathways rather than uniform effects, with persistently low positive affect representing a specific mechanism linking early adversity to later depression and anxiety. Findings suggest that targeting positive emotional experiences may be a promising intervention strategy for youth exposed to ELA.