• obsessive–compulsive disorder;
  • comorbidity;
  • anxiety;
  • depression;
  • panic disorder;
  • family studies


To understand the familial relationship between obsessive–compulsive disorder (OCD), other anxiety disorders, and major depressive disorder (MDD), we examined the rates of anxiety disorders and MDD in first-degree relatives of OCD probands and controls, the association between age at onset of OCD and the occurrence of other anxiety disorders and major depressive disorder in relatives of probands, and the co-transmission of specific anxiety disorders, MDD, and OCD within families of probands. Recurrence risks were estimated from 466 first-degree relatives of 100 probands with OCD and 113 first-degree relatives of 33 non-psychiatric controls. Rates of non-OCD anxiety disorders and MDD were comparable in relatives of OCD probands and controls. Rates of anxiety disorders and MDD were higher among case relatives with OCD than among case relatives without OCD and control relatives. Fifty percent of case relatives with OCD had at least one comorbid anxiety disorder. Early age at onset (<10 years) in probands was associated with higher rates of anxiety and depression comorbidity among case relatives with OCD but not among case relatives without OCD. The occurrence of specific anxiety disorders and MDD in case relatives was independent of the same comorbid diagnosis in the OCD probands. OCD, panic disorder, generalized anxiety disorder, and MDD occurred together more often than expected by chance among individuals with OCD. Furthermore, age at onset in probands is associated with specific anxiety and affective comorbidity among case relatives. These findings support the hypothesis that early- and late-onset OCD represent different etiologic variants. Depression and Anxiety 20:165–174, 2004. © 2005 Wiley-Liss, Inc.