The genetics of depression in childhood and adolescence.

This article reviews family, twin, and adoption studies of childhood and adolescent depression. Results from several family and twin studies suggest that an etiologic heterogeneity exists in depression in childhood and adolescence. Twin studies show that genetic influences on depression in young people may be indirect and work via effects on environmental risk exposure (gene-environment correlation) or genetic sensitivity to environmental risks (gene-environment interaction). Recent research on gene-environment interaction has examined the effect of specific functional genetic polymorphisms in conjunction with environmental stressors. Future research needs to work toward identifying which environmental and genetic risk factors are crucial to the development of depression in youth, as well as mechanisms involved in the familial transmission of depression. This will not only improve understanding of the etiology of childhood and adolescent depression but also inform the development of therapeutic and preventive interventions.