DOES CLOZAPINE CAUSE TARDIVE-DYSKINESIA

Background: The authors attempted to determine if chronic exposure to clozapine can cause tardive dyskinesia. Method: Twenty-eight schizophr enic or schizoaffective patients with no prior history of definite tar dive dyskinesia were treated with clozapine for at least 1 year, and t heir ongoing modified Simpson Dyskinesia Scale ratings were analyzed. These data were then compared with those of another group of similarly diagnosed patients who were treated with a conventional neuroleptic f or at least 1 year. Results: Two patients in the clozapine-treated gro up (both of whom had ratings of questionable tardive dyskinesia at bas eline) were later rated by the modified Simpson Dyskinesia Scale as ha ving mild tardive dyskinesia on at least two consecutive ratings 3 mon ths apart. Although there was uncertainty about whether clozapine defi nitely caused the tardive dyskinesia in those two patients, a survival analysis comparing the clozapine-treated group with the neuroleptic-t reated group showed a lower risk of tardive dyskinesia developing in t he clozapine-treated group. Conclusion: This study was unable to defin itively conclude whether clozapine causes tardive dyskinesia. However, if cases do develop, the risk of tardive dyskinesia is likely to be l ess with clozapine than with typical neuroleptics.