A recent reviews of published researchers suggest, that up to 25% of schizophrenia patients suffer from obsessive-compulsive symptoms (OCs) and about 12% fulfill the diagnostic criteria for obsessive-compulsive disorder (OCD). Recently, the interest in this issue has significantly increased, probably due to the finding, that second generation antipsychotics, especially clozapine, might induce or aggravate OCs.

The aim of our study was to investigate and clarify the literature data about the extent to which comorbid OCs affects the severity and course of schizophrenia.

The articles were identified by the keywords “schizophrenia comorbidity” and “obsessive compulsive disorder”, using the medline and web of science search. Additional information was obtained by studying the references of summaries of relevant articles.

Obsessive-compulsive symptoms or fully expressed obsessive-compulsive disorder leads to more severe overall psychopathology and poorer treatment outcomes in patients with schizophrenia. This comorbidity is accompanied by increased neurocognitive impairment, high levels of anxiety, depression, and suicidality, less favorable levels of social and vocational functioning, and greater social and health service utilization.

In clinical practice, schizophrenia patients should be carefully monitored for OCs, which may occur at any time during the schizophrenia disease. Early recognition and targeted treatment of this comorbidity reduce patient's distress; positively influence the course of illness and overall treatment outcome.

The authors have not supplied their declaration of competing interest.