Greg Hajcak

The psychophysiological underpinnings of preschool‐onset depression (PO‐MDD) remain underexplored. Moreover, there is currently a limited understanding of the potential impact that PO‐MDD might have on neurobiological functions later in development such as general cognitive domains and reward processing. Thus, the current study sought to examine potential neurophysiological differences, measured via electroencephalography (EEG), in adolescents with and without a history of PO‐MDD. Participants and their caregivers ( N = 138) from a large longitudinal study completed semi‐structured clinical interviews at a baseline visit (ages 3–7) to determine PO‐MDD status. At a follow‐up visit approximately 11 years later, adolescents (ages 13–19) completed the doors gambling task while EEG was recorded to measure event‐related potentials (ERPs) elicited by both the doors and feedback stimuli, to index cognitive and reward processing functions (i.e., doors‐P300, gain/loss feedback‐P300, and RewP). Adolescents with a history of PO‐MDD exhibited significantly smaller doors‐P300 compared with adolescents with no history of PO‐MDD, whereas there were no group differences in gain/loss feedback‐P300 or RewP. Additionally, reduced doors‐P300 was independently associated with lower baseline income‐to‐needs ratio, older age, and female gender. The current study suggests that reduced doors‐P300 amplitude during adolescence might reflect impaired neurophysiological development related to PO‐MDD. Thus, the P300 derived from the doors stimuli might be a valuable neural measure to further our understanding of potential neurophysiological differences associated with early‐onset childhood depression.