Family, genetic, and imaging studies of early-onset depression

As with other psychiatric disorders, most studies dealing with the familiality and genetics of depression have been limited to adults; however, several studies suggest that there is continuity between childhood- and adolescent-onset depression and adult depression. More direct estimates of the heritability of depressive symptoms or episodes in children and adolescents are compatible with the genetic contributions being greater than 50%. A number of functional and structural imaging studies have implicated particular circuitry as being involved in the generation of emotion and depression. Imaging studies of twins have suggested that regional brain volume and characteristics of brain shape are heritable. This suggests that a potentially important new avenue of research will be the correlation of the genetics of brain structure and/or function with the genetics of depression. Preliminary studies of adolescent and young adult twins suggest a significant correspondence between the genetic contributions to some regional brain volumes and early-onset depression.