Early life stress (ELS) is one of the largest environmental risk factors for depression, yet the mechanisms underlying this relationship are still being investigated. Much literature has implicated alterations in cortisol and brain structure/function as potential mediating factors. Here, we review evidence associating ELS with later depression, including effects of sexual abuse, poverty, and parental psychopathology. While depression has shown relatively consistent relationships with elevated cortisol, blunted cortisol levels are often associated with ELS, though this varies by a variety of factors, such as methodology and age. Further, there is growing evidence that ELS and depression relate to similar alterations in brain structure/function, particularly in the hippocampus, amygdala, medial prefrontal cortex, and regions of the anterior cingulate cortex. While this potentially suggests that ELS contributes to neural alterations associated with depression, only a small, though growing, body of human studies explicitly test how cortisol and the brain may mediate the effects of ELS.
Systems Neuroscience in Depression, 2016, Pages 29-77,