소 아 • 청소년의 우울장애

Depressive Disorder in Children and Adolescents

Although no unifying, explanatory theory of the etiology of depression emerges from the results of studies reviewed above, the findings do support several conclusions concerning the the depression in children and adolescents. First, a subgroup of depressed children or adolescents have a geneticallybased vulnerability for the expression of depressive disorders. Using technologies currently available, molecular biologist should soon be able to identify the specific gene associated with depression in children and adolescents in a particular family. It should then be possible to clone the gene and eventually to understand the functional significance. In addition, once it is possible to identify individuals who carry the gene, high risk paradigms can be applied to study affected and unaffected family members and to elucidate the nongenetic factors that contribute to the expression of and ultimate severity of the disorder in an individual. “Protective factors” and effective preventive interventions could also be identified. Finally, once the pathophysiology of one subtype of depression is understood, this knowledge can inform research aimed at understanding the pathophysiolgy of depression in individuals who are depressed but who do not have the same etiologic factors. Second, considerable evidence indicates that the pathophysiology of depression in children is different from that in adults, but in adolescents, similar to that in adults. In order to understand this finding, developmental charateristics should be taken into consideration. Many other findings in adults await replication in children and adolescnts. Third, despite similarities, the results of some biological measures in depressed adolescents are different from those seen in adults and prepubertal children. In human being, there are lines of evidence that the functional development of monoamine systems in childhood and adolescence may be different from adulthood. For instance, 1) Normally, the attention span of young children is short but improved as they become older, which may be related to the functional development of catecholaminergic system. 2) Clinically, the manic symptoms are fairly rare in children and adolescents. 3) The response to CNS stimulants is somewhat different in childhood and adolescents from adults. In adults, they frequently show excitatory elated or euphoric response to amphetamine, but in children, they rarely show such response, and drug addiction is extremely rare in children. 4) The response to antidepressant is different in children and adolescents compared to adults. Overall response rate is very poor in children and adolescents and rebound hypomanic episode due to antidepressant is extremely rare in children and adolescents. These findings suggest that in order to understand the differences in biological findings in children and adolescents, ontogenetic characterictics of neurotransmitter systems should be taken into considerations.