Commentary: beyond stressful life events and depression? --reflections on Bogdan et al. ().

In light of continuing disagreement, even at the meta-analytic level, as to whether the gene- × -environment (G×E) interaction involving 5-HTTLPR and stressful life events (SLEs) predicts depression, Bogdan and associates (this issue, Bogdan et al., 2014) sought to extend research on what has become a highly controversial general (GxE) and specific (5HTTLPR X SLEs) arena of inquiry. Thus, rather than seeking to replicate this specific GXE interaction in another sample of adolescents or adults, these investigators shifted the developmental focus-to very young children, aged 3-5 years of age. This re-direction was motivated by the kindling hypothesis which stipulates that the earliest episodes of depression might be especially sensitive to environmental adversity, with later episodes very much dependent on earlier ones and less a function of later-life environmental provocation. Thus, the investigators reasoned that the controversial G×E interaction might actually prove more evident and exert a more pronounced impact early in childhood than at older ages where they have been so extensively studied.