Symptom structure of antipsychotic-induced obsessive compulsive symptoms in schizophrenia patients

The use of clozapine or other second generation antipsychotics (SGAs) has been reported to produce obsessive compulsive (OC) symptoms as adverse mental affects. However, it is not yet clear if SGA-induced OC symptoms have the same phenomenological characteristics as those displayed in obsessive compulsive disorder (OCD). This study investigated the nature of symptoms and dimensions of SGA-induced OC symptoms in schizophrenia patients, which were then compared with those reported in pure OCD.

The study subjects were fifty-one schizophrenia patients with SGA-induced OC symptoms. Symptom evaluation was performed using the Korean version of the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). Exploratory factor analysis of symptom categories of Y-BOCS symptom checklist (Y-BOCS-SC) was conducted.

Frequencies of individual symptom categories were comparable to those reported in Korean OCD patients. Five factors (forbidden thoughts, hoarding, cleaning, symmetry, and counting) were generated from 13 main symptom categories, which accounted for 70.7% of the total variance. This factor structure is also remarkably similar to those reported in pure OCD patients. The factor score of 'cleaning' was significantly correlated with the overall severity of OC symptoms (P<0.01).

A high level of similarity between the nature of symptoms and dimensions identified in patients with SGA-induced OC symptoms and those revealed in OCD patients suggests a common biological mechanism underlying these two clinical conditions.