Aberrant striatal tracking of reward magnitude in youth with current or past-year depression.

Reward dysfunction is often present in youth with major depressive disorder (MDD), but the specific neurobiological bases underlying reward valuation deficits remain unclear. The current study examined whether adolescents and young adults with MDD track brain and behavioral responses according to relative reward magnitude-a neurocognitive valuation process known as magnitude tracking. Female adolescents and young adults ages 15-20 years (n = 56 with current or past-year MDD; n = 26 healthy controls [HCs]) completed a task during functional neuroimaging in which they could win or lose money at high stakes (+$1/-50(sic)) and low stakes (+20(sic)-10(sic)). Behaviorally, HC accelerated button press responses on high stakes compared to low-stakes trials, whereas MDD did not alter response speed across stakes. Neurally, HC increased recruitment of the ventral and dorsal striatum, canonical reward-processing regions, for high-magnitude versus low-magnitude rewards, However, the MDD group did not exhibit striatal magnitude tracking for low versus high rewards-an effect independent of MDD recency, MDD symptom severity, comorbid anxiety and substance use disorders, and psychiatric medication use. In contrast, striatal recruitment for overall reward reactivity, measured by comparing striatal activity for reward and loss feedback, was similar in the MDD and HC groups. However, reward reactivity was negatively correlated with current depression symptom severity in the MDD group. Taken together, these findings suggest that whereas reward reactivity may vary with current depression severity, reward magnitude tracking may represent an important aberrant valuation process in youth with depression-independent of symptom severity and recency. This valuation deficit may have implications for maladaptive motivation and learning observed in youth with MDD.