Obsessive-compulsive disorder in schizophrenia: clinical characteristics and treatment.

There is a considerable overlap of schizophrenia and obsessive-compulsive disorder (OCD) in the structural and functional brain abnormalities involved, role of the dopamine/serotonin neurotransmitter systems, and some demographic and clinical characteristics. Although OCD co-occurs in a substantial proportion of schizophrenia patients, a systematic evaluation of the clinical features and treatment of this population is lacking. This review critically evaluates findings of recent studies pertaining to the rate of occurrence of OCD or obsessive-compulsive symptoms (OCS) in schizophrenia and the clinical characterisation of the schizo-obsessive subtype. Specifically, interrelationships between obsessive-compulsive and schizophrenic symptoms in terms of temporal relationships and their association with specific schizophrenia subtypes and the effect of OCS on the severity of schizophrenia symptoms are addressed. In the absence of evidence-based data, tentative therapeutic approaches in this difficult-to-treat patient subgroup are suggested. These include monotherapy with atypical antipsychotic agents or a combination of either typical or atypical antipsychotics with SSRIs or clomipramine. The clinical characteristics of antipsychotic-induced OCS/OCD are also presented to facilitate identification and management of this rare but clinically significant adverse effect. Finally, future directions of research in schizophrenia-OCD comorbidity relevant to clinical practice are discussed.