Lifetime psychopathological characteristics associated with comorbid obsessive-compulsive disorder in clinically stable patients with chronic schizophrenia.

Obsessive-compulsive symptoms (OCS) commonly occur in the course of schizophrenia. The aim of this study was to investigate the rate of obsessive-compulsive disorder (OCD) in patients with chronic schizophrenia and evaluate lifetime correlates of the comorbidity. Subjects were clinically stable patients with chronic schizophrenia (n = 320). Patients having comorbid OCD and those without OCD were compared in terms of symptoms dimensions and cognitive function. OCD was found in 20.6 % of subjects. Earlier age at onset, male gender, higher level of education, comorbid panic disorder, and specific phobia were associated with comorbid OCD. In terms of lifetime symptoms, depression (p = 0.001) and anxiety (p = 0.014) showed significant association with the comorbidity, which corroborates with our previous study findings regarding OCD in bipolar disorder. In addition, decreased emotional response (p = 0.016), less formal thought disorder (p = 0.007), and less prodromal impairment (p = 0.005) were independently associated with the comorbidity. The OCD group showed better performance in working memory domain (p = 0.027) while other cognitive domains did not show any significant difference between the two groups. Association of OCSs with depressive symptoms and other comorbid anxiety disorders seems to be a common finding across schizophrenia and bipolar disorder. This study also suggests that comorbidity of OCD in schizophrenia is associated with less impairment of thought process and cognitive function throughout the disease course.