Obsessive-Compulsive Symptoms in Schizophrenia and in Obsessive-Compulsive Disorder: Differences and Similarities

Introduction: A growing literature suggests that obsessive-compulsive (OC) phenomena represent a distinct dimension in schizophrenia, independent of nuclear psychotic symptoms. Nevertheless, the OC psychopathologic profile in schizophrenia, compared with "pure" obsessive-compulsive disorder (OCD), has not yet been investigated extensively. This study investigated the clinical features of the OC dimension in patients with schizophrenia compared with patients with pure OCD. Methods: The main psychopathologic features of obsessions and compulsions were rated in 35 patients with schizophrenia and 31 patients with OCD, using the Structured Clinical Interview for DSM-IV Axis I Disorders, the Positive and Negative Syndrome Scale, the Yale-Brown Obsessive-Compulsive Scale, and the Leyton Obsessional Inventory. Results: OC phenomena were indistinguishable in terms of their severity, resistance, interference, and control in both groups. However, patients with OCD showed higher rates of aggressive, contamination-related, sexual, and somatic themes; moreover, in the group with schizophrenia, a positive relationship was found between washing compulsions and delusions and between hoarding obsessions and delusions. Conclusions: These results indicate that patients with schizophrenia exhibit a narrower range of obsessive content compared with patients with OCD; in addition, OC and delusional themes tend to be related in schizophrenia as a unique symptomatic phenomenon.