Clozapine-induced tardive dyskinesia in schizophrenic patients taking clozapine as a first-line antipsychotic drug

Objective. Clozapine causes few extrapyramidal symptoms and is recommended as a treatment drug for severe tardive dyskinesia (TD). However, several case reports have suggested that clozapine could also cause TD. We investigated whether clozapine used as a first-line antipsychotic drug can cause TD. Method. We identified 101 patients at Yanbian Socio-Mental Hospital and Yanbian Brain Hospital in China who had received clozapine as a primary antipsychotic drug since their first episode of illness and evaluated the prevalence rate, type, and severity of TD using the Extrapyramidal Symptoms Rating Scale (ESRS). The criterion for TD was a score of≥ 3 on one item or 2 on two or more items of the ESRS. Results. The mean age and duration of illness of the patients were 38.93±8.36 and 12.88±6.90 years, respectively. The mean duration of clozapine treatment was 12.10±6.26 years. The prevalence of TD was 3.96% (4/101). Compared to patients without TD, patients with TD had a long duration of illness and clozapine treatment; all had the orolingual type of TD. TD was relatively mild, with a mean score of 4.75, and tended to accentuate with an activation procedure of rapid pronation and supination of the hands. Conclusions. These results suggest that clozapine may cause TD; however, the prevalence is low and the severity is relatively mild, with no or mild self-reported discomfort. Therefore, we recommend that regular examination for TD using the activation procedure should be performed in patients who use clozapine on a long-term basis.