Neural Indicators of Anhedonia: Predictors and Mechanisms of Treatment Change in a Randomized Clinical Trial in Early Childhood Depression

Background Early childhood depression is associated with anhedonia and reduced event-related potential (ERP) responses to rewarding or pleasant stimuli. Whether these neural measures are indicators of target engagement or treatment outcome is not yet known. Methods We measured ERP responses to win and loss feedback in a guessing task and to pleasant versus neutral pictures in young (4.0–6.9 years of age) depressed children before and after randomization to either 18 weeks of Parent-Child Interaction Therapy–Emotion Development (PCIT-ED) or waitlist. Results Analyses included reward positivity (RewP) data from 118 children randomly assigned to PCIT-ED (n = 60) or waitlist (n = 58) at baseline and late positive potential (LPP) data from 99 children (44 assigned to PCIT-ED vs. 55 assigned to waitlist) at baseline. Children undergoing PCIT-ED showed a greater reduction in anhedonia (F1,103 = 10.32, p = .002, partial η2 = .09). RewP reward responses increased more (F1,86 = 5.98, p = .02, partial η2 = .07) for PCIT-ED, but a greater change in RewP was not significantly associated with a greater reduction in major depressive disorder symptoms (r = −.12, p > .4). Baseline RewP did not predict treatment change. LPPs to positive pictures did not change across treatment, but greater baseline LPPs to positive pictures predicted a higher likelihood of remission from major depressive disorder in children undergoing PCIT-ED (B = 0.14; SE = 0.07; odds ratio = 1.15; p = .03). Conclusions The ERP reward response improved in young children with depression during a treatment designed to enhance emotion development, providing evidence of target engagement of the neural systems associated with reward. Further, greater baseline LPP responses to positive pictures was associated with a greater likelihood of depression remission, suggesting that this ERP measure can predict which children are most likely to respond to treatment.