Disentangling gene-environment correlations and interactions on adolescent depressive symptoms.

BACKGROUND Genetic risks for depression may be expressed through greater exposure towards environmental stressors (gene-environment correlation, rGE) and increased susceptibility to these stressors (gene-environment interaction, G x E). While these effects are often studied independently, evidence supports their co-occurrence on depression. METHODS Adolescent twin and sibling data was used to assess correlations and interactions between genetic risks for depressive symptoms and two putative environmental stressors: dependent negative life events and maternal punitive discipline. RESULTS Moderate genetic effects influenced each environmental risk factor, consistent with rGE. Genetic effects on environmental risks also contributed to depressive outcomes, implying genetic correlations between measures. Genetic effects on depressive symptoms changed across levels of negative life events and maternal punitive discipline, consistent with G x E. Finally, G x E co-occurred with rGE on depressive outcomes. CONCLUSIONS Adolescents at genetic risk for depressive phenotypes may be exposed to increased social adversity (rGE) and more susceptible to developing symptoms in response to these risks (G x E).