Reward can influence cognitive control; however, dysfunctional interactions between reward and cognitive control in adolescents with major depressive disorder (MDD) remain unclear.

We recruited 35 adolescents with MDD and 29 healthy controls (HC) who completed the AX version of the Continuous Performance Test (AX-CPT) under reward and non-reward conditions, while undergoing functional Near-Infrared Spectroscopy (fNIRS).

Adolescents with MDD exhibited slower response times and higher error rates compared to healthy controls. Under reward conditions, they responded more quickly but made more errors. Hierarchical Drift Diffusion Modeling (HDDM) revealed that adolescents with MDD showed a reduced starting bias toward more rewarding responses and a broader decision threshold in reward contexts. Neuroimaging results indicated that the MDD group showed diminished activation differences in the left dorsolateral prefrontal cortex (DLPFC), left ventrolateral prefrontal cortex (VLPFC), and right VLPFC in response to cues requiring high versus low cognitive control. Additionally, they exhibited weaker functional connectivity between these regions during reward-related cognitive control. Correlation analyses further showed that greater anhedonia severity was associated with poorer behavioral performance and less flexible activation in the prefrontal cortex.

Cognitive control impairments in depressed adolescents may be related to dysfunction in the motivational system. Our findings provide behavioral, computational, and neural evidence for the Expected Value of Control (EVC) theory. Diminished reward sensitivity and inflexible cognitive control may jointly contribute to these deficits, highlighting the importance of considering motivational factors in the diagnosis and intervention of cognitive control impairments in adolescents with depression.