Depressive disorders in childhood. III. A longitudinal study of comorbidity with and risk for conduct disorders.

As part of a longitudinal nosologic study of major depressive disorder (MDD), dysthymic disorder, and adjustment disorder with depressed mood in 104 school-aged probands, the prevalence and consequences of comorbid conduct disorders (CD) were examined. During the index depressive episodes, 16% of the patients had comorbid CD; during the full study observation 23% had CD; and the estimated time-dependent risk of conduct disorder developing was 36% by age 19. For most cases, comorbid CD developed as a complication of the depression and persisted after the depression remitted. Comorbid CD was not differentially associated with the type of depression at study entry, did not affect depressive symptom presentation, was similarly distributed among boys and girls, and was unrelated to demographic factors. Additionally, comorbid CD did not affect recovery from the index depressive episodes and did not influence the symptom-free interval before a recurrent depression among cases with MDD. The risk of CD developing was not altered by chronologically earlier family variables or demographic factors. But girls who had attention deficit disorder, compared to those who did not, seemed to be at higher risk for CD during study observation. Finally, in this depressed cohort, having CD any time was associated with an increased rate of long-term functional problems.