Early life interpersonal stress and depression: Social reward processing as a potential mediator.

Experiencing stressful events early in life is lamentably very common and widespread across the globe. Despite the strong link between experiencing such stress and developing depression, the mechanisms underlying this association remain unclear. This review addresses this critical question by drawing focus to "early life interpersonal stress" (ELIS), or stressful experiences that occur within the context of a relationship where there is close, direct interaction. Recent evidence suggests that ELIS uniquely relates to depression. A growing body of work demonstrates that ELIS impacts how youth respond to social reward (e.g., positive social stimuli/ feedback). Similar social reward-related impairments are noted in youth with depression. The current review synthesizes these two disparate, yet related, bodies of literature examining the relations between a) ELIS and neurobehavioral alterations in social reward processing; and b) behavioral and neural processing of social reward in depression. A preliminary model presents neurobehavioral disruptions in social reward processing as one mediating factor underlying the connection between ELIS and depression. Key limitations and future directions are discussed.