Preferential aggregation of obsessive-compulsive spectrum disorders in schizophrenia patients with obsessive-compulsive disorder

Objective: To validate a complex association between schizophrenia and obsessive-compulsive disorder (OCD). Method: We used the Structured Clinical Interview for DSM-IV Axis I disorders to compare the rate of OCD spectrum and additional Axis I disorders in 100 patients who met criteria for both schizophrenia and OCD, non-OCD schizophrenia (n = 100), and OCD (n = 35). Results: There was a robust between-group difference in the number of patients with one or more OCD spectrum disorders (schizo-obsessive n = 30, compared with schizophrenia n = 8; P = 0.001), that is, higher rates of body dysmorphic (8% compared with 0%) and tic (16% compared with 4%) disorders. No difference was revealed in affective, anxiety, and substance use disorders. We found comparable rates of OCD spectrum disorders in the schizo-obsessive and OCD groups (30% and 42.8%, respectively; P = 0.32). Conclusion: Preferential aggregation of OCD spectrum disorders in the schizo-obsessive group supports this unique clinical association. Whether a schizo-obsessive interface represents comorbidity or a specific subtype of schizophrenia warrants further investigation.