Objective: To examine whether depression aggregates in the families of depressed adolescents and to determine whether clinical features and/or comorbid syndromes in the depressed adolescents change the risk of psychopathology in relatives.
Method: Lifetime prevalence rates of psychopathology in the first-degree (n = 228) and second-degree (n = 736) relatives of 76 adolescents with major depressive disorder (MDD) and the first-degree (n = 107) and second-degree (n = 323) relatives of 34 normal control adolescents were assessed by the Family History-Research Diagnostic Criteria (FH-RDC) method using the parent/guardian as the family informant.
Results: Compared with the first-degree relatives of normal controls, the relatives of depressed adolescents had significantly higher lifetime rates of MDD (25% versus 13%) and "any" of the FH-RDC psychiatric disorders (53% versus 36%). The second-degree relatives of adolescents with MDD had significantly higher lifetime rates of FH-RDC "other" psychiatric disorder (12% versus 7%) and "any" of the FH-RDC psychiatric disorders (22% versus 15%) but not MDD (5% versus 6%) compared with the relatives of normal controls. The first-degree relatives of depressed adolescents who were also suicidal had increased lifetime rates of suicidal behavior which significantly cosegregated with MDD. Comorbid conduct disorder in the depressed adolescent was associated with increased rates of antisocial personality disorder in the first-degree relatives and also tended to cosegregate with MDD.
Conclusions: The current study provides further evidence for the familial aggregation of depression in adolescent-onset MDD. This study also suggests that the familial aggregation of nonaffective psychiatric disorders depends on the clinical features and comorbid syndromes present in the depressed adolescent proband.