Current research trends in early life stress and depression: Review of human studies on sensitive periods, gene-environment interactions, and epigenetics

Early life stress, such as childhood abuse, neglect and loss, is a well established major risk factor for developing depressive disorders later in life. We here summarize and discuss current developments in human research regarding the link between early life stress and depression. Specifically, we review the evidence for the existence of sensitive periods for the adverse effects of early life stress in humans. We further review the current state of knowledge regarding gene × environment (G × E) interactions in the effects of early life stress. While multiple genes operate in multiple environments to induce risk for depression after early life stress, these same genes also seem to enhance the beneficial effects of a positive early environment. Also, we discuss the epigenetic mechanisms that might underlie these G × E interactions. Finally, we discuss the potential importance of identifying sensitive time periods of opportunity, as well as G × E interactions and epigenetic mechanisms, for early interventions that might prevent or reverse the detrimental outcomes of early life stress and its transmission across generations.