Abstract
Pediatric major depressive disorder (MDD) is a debilitating disorder with long-term negative health risks. Understanding the affective neurobiological mechanisms of pediatric MDD may be crucial for refining assessment and identifying intervention targets. To systematically review the literature on affective brain function in pediatric MDD, PubMed and PsycInfo databases were searched to identify task-based affective functional magnetic resonance imaging (fMRI) studies statistically comparing children and adolescents currently diagnosed with MDD to healthy controls. Twenty-six studies met inclusion criteria and assessed neural constructs related to positive valence, negative valence, affective cognitive control, and self-related affective processing. The most consistent group differences among depressed compared to healthy youth observed were higher levels of amygdala blood oxygen–level dependent (BOLD) response to negatively valenced stimuli and lower levels of striatal BOLD response to positively valenced stimuli, respectively suggesting heightened negative affective reactivity and blunted reward processing. Findings also implicated extended medial prefrontal and salience network regions, including aberrant function in medial prefrontal cortex (mPFC), lateral PFC, insula, and anterior cingulate cortex (ACC); however, the directions of effects were mixed and may be context specific. In all, studies reviewed here underscore affective dysfunction in pediatric MDD and highlight the need to systematically consider neural responsivity in pediatric MDD across contexts.