Impact of Age at Onset and Duration of Illness on the Expression of Comorbidities in Obsessive-Compulsive Disorder.

Background: Obsessive-compulsive disorder (OCD) patients usually experience comorbidities including tics, trichotillomania, body dysmorphic disorder, and mood and anxiety disorders. The present report verifies how age at onset of obsessive-compulsive symptoms and duration of illness are associated with comorbid diagnoses in OCD patients.

Method: Psychiatric comorbidity was assessed using a structured clinical interview in 161 consecutive outpatients referred for treatment between 1996 and 2001 who met DSM-IV criteria for OCD. Age at onset and duration of illness were retrospectively assessed by direct interviews.

Results: An earlier age at onset of obsessive-compulsive symptoms was associated with tic disorders, while longer illness duration was associated with depressive disorder (major depressive disorder or dysthymia) and social phobia.

Conclusion: Age at onset and duration of OCD illness are meaningful variables affecting the expression of comorbidities in OCD. Tic disorders and OCD may share common etiologic pathways. Depressive disorders, in contrast, may be secondary complications of OCD.