Early life stress moderates the relation between systemic inflammation and neural activation to reward in adolescents both cross-sectionally and longitudinally.

Elevated levels of systemic inflammation are associated with altered reward-related brain function in ventral striatal areas of the brain like the nucleus accumbens (NAcc). In adolescents, cross-sectional research indicates that exposure to early life stress (ELS) can moderate the relation between inflammation and neural activation, which may contribute to atypical reward function; however, no studies have tested whether this moderation by ELS of neuroimmune associations persists over time. Here, we conducted a cross-sectional analysis and the first exploratory longitudinal analysis testing whether cumulative severity of ELS moderates the association of systemic inflammation with reward-related processing in the NAcc in adolescents (n = 104; 58F/46M; M[SD] age = 16.00[1.45] years; range = 13.07-19.86 years). For the cross-sectional analysis, we modeled a statistical interaction between ELS and levels of C-reactive protein (CRP) predicting NAcc activation during the anticipation and outcome phases of a monetary reward task. We found that higher CRP was associated with blunted NAcc activation during the outcome of reward in youth who experienced higher levels of ELS (β = -0.31; p = 0.006). For the longitudinal analysis, we modeled an interaction between ELS and change in CRP predicting change in NAcc activation across 2 years. This analysis similarly showed that increasing CRP over time was associated with decreasing NAcc during reward outcomes in youth who experienced higher levels of ELS (β = -0.47; p = 0.022). Both findings support contemporary theoretical frameworks involving associations among inflammation, reward-related brain function, and ELS exposure, and suggest that experiencing ELS can have significant and enduring effects on neuroimmune function and adolescent neurodevelopment.