Adolescents’ ventral striatal reward neural activity moderates the association between lifetime trauma exposure and lower depression after 6 months

<b>Background:</b> Lifetime trauma exposure is associated with higher-severity depression and anhedonia. Neural reward regions develop in adolescence and influence depression and anhedonia. Reward regions may enhance the impact of trauma exposure on depression. This naturalistic, 6-month longitudinal study examined how individual differences in the function of reward regions impact associations between lifetime trauma exposure and the development of depression and anhedonia in adolescents.<b>Methods:</b> 82 participants aged 13-19 years varying in risk for depression and anhedonia reported lifetime trauma exposure, depression, and anhedonia and underwent a monetary reward fMRI task at baseline, then reported symptoms 6 months later. Neural reward activity to reward > neutral outcome (<i>p</i>_FWE<.05) was measured within the Neurosynth 'reward' mask. Univariate models examined whether activity in neural reward regions moderated the impact of lifetime trauma on the development of depression and anhedonia after 6 months, correcting for baseline symptoms.<b>Results:</b> Lifetime trauma exposure was associated with higher baseline depression (<i>β</i> = 1.676, <i>p</i> = .019) and anhedonia (<i>β</i> = 1.547, <i>p</i> < .001), and higher anhedonia at 6-months (<i>β</i> = 2.050, <i>p</i> < .001). Neural activity to reward outcome occurred in the bilateral ventral striatum (VS), anterior cingulate cortex, and right ventrolateral prefrontal cortex. Right VS activity moderated prospective relationships between lifetime trauma exposure and depression at 6 months (<i>β</i> = -3.275, <i>p</i> = .037), where greater trauma was associated with lower depression 6 months later for those with higher right VS activity.<b>Conclusion:</b> Reward neural network activity was associated with improvements in depression in individuals with more lifetime trauma exposure. Targeting reward network function or using psychosocial strategies to enhance positive affect may be an important strategy to address depression, particularly among adolescents exposed to trauma.