Obsessive-compulsive disorder in schizophrenia: epidemiologic and biologicoverlap

Objective: To examine the co-existence of obsessive-compulsive disorder (OC D) with schizophrenia in terms of epidemiology and overlapping biologic sub strates. Methods: Review of the relevant literature. Results: There appears to be a significant prevalence of OCD in schizophrenia - higher than what would be expected on the basis of calculated comorbidity figures. There is significant overlap in the proposed functional circuits of OCD and schizoph renia, which may lead to co-expression of symptoms. Although there is overl ap in neurotransmitter dysfunction, the interactions are complex, especiall y in regard to the serotonin and dopamine systems. Conclusion: The expressi on of OCD in schizophrenia is complex but very intriguing. Theoretical hypo theses of the pathology of the 2 disorders now need to be tested in larger controlled trials.