A family study of major depressive disorder in a community sample of adolescents

Background: Most family studies of major depressive disorder (MDD) take a top-down approach, examining the rate of the disorder in offspring of adults with MDD; however, most children and adolescents with MDD have parents who do not have the disorder. This study employed a bottom-up approach in examining children and adolescents with MDD and their firstdegree relatives. Methods: Probands included 3 groups of adolescents: 268 with history of DSM-III-R MDD, 110 with history of nonmood disorders but no MDD, and 291 with no history of mental illness through 18 years of age. All first-degree relatives (> 13 years) were assessed for psychiatric disorders via semistructured direct and family history interviews, after which best-estimate DSM-IV diagnoses were derived. Results: Relatives of probands with MDD had higher rates of MDD (hazard ratio [HR] = 1.77, 95% confidence interval [CI] = 1.46 to 2.31) and dysthymia (HR = 1.79, 95% CI = 1.11 to 2.87) than relatives of the other proband groups, but, with the exception of alcohol abuse (HR = 1.29, 95% CI = 1.05 to 1.53), did not have higher rates of nonmood disorders. In addition, female relatives of MDD probands had a significantly higher rate of MDD than male relatives (HR = 1.41, 95% CI = 1.12 to 1.78), and the rate of MDD was higher in female than male relatives of female proj bands (HR = 1.79, 95% CI = 1.37 to 2.34). Although relatives of probands with anxiety and substance use disorders had elevuled rates of those disorders, nonmood disorders in probands were not associated with higher rates of MDD in relatives. Conclusions: These findings are in line with earlier studies that found; substantial familial aggregation of adolescent MDD and suggest that MDD is transmitted with a high degree of specificity. They also show a significant familial aggregation for most broad categories of nonmood disorders.