Relationship between severity of obsessive-compulsive symptoms and schizotypy in obsessive-compulsive disorder

PURPOSE Obsessive-compulsive disorder (OCD) patients exhibit a noninhibition response pattern very similar to that observed in schizotypy patients in cognitive tasks. It has been suggested that the reduced cognitive inhibition observed in both schizotypy and OCD may result in the frequent entry into awareness of unacceptable urges and intrusive thoughts. The aim of this study was to investigate the relationship between the severity of obsession or compulsion and schizotypy in OCD. PATIENTS AND METHODS Sixty subjects (25 males and 35 females) who were OCD outpatients in the University Hospital at the Kyoto Prefectural University of Medicine during the period 2008-2010 were enrolled in the study. Assessments of these patients were made using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), the Schizotypal Personality Questionnaire (SPQ), the Hamilton Depression Rating Scale (HAM-D), and the Hamilton Anxiety Rating Scale (HAM-A). The Pearson correlation coefficients between Y-BOCS and SPQ scores were calculated. Furthermore, hierarchical multiple linear regression analyses were conducted to assess whether schizotypy predicted the severity of obsession and compulsion. RESULTS By calculating the Pearson correlation coefficient, it was found that the Y-BOCS obsession score, not the Y-BOCS compulsion score, was correlated with the SPQ total score. Results of the hierarchical multiple linear regression analysis showed that SPQ total score was a significant predictor of the Y-BOCS obsession score, after accounting for control variables (ie, HAM-D and HAM-A). CONCLUSION Results of this study showed that the Y-BOCS obsession score, not the Y-BOCS compulsion score, was correlated with the SPQ total score. This finding suggests that OCD patients with an elevated SPQ total score experience a reduction of cognitive inhibition, resulting in the frequent entry into obsession. Future longitudinal studies are recommended to clarify the effect of schizotypy on the clinical course of OCD.