title: Does clozapine cause tardive dyskinesia?
abstract: BACKGROUND
  The authors attempted to determine if chronic exposure to clozapine can cause tardive dyskinesia.
  
  
  METHODS
  Twenty-eight schizophrenic or schizoaffective patients with no prior history of definite tardive dyskinesia were treated with clozapine for at least 1 year, and their 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 for at least 1 year.
  
  
  RESULTS
  Two patients in the clozapine-treated group (both of whom had ratings of questionable tardive dyskinesia at baseline) were later rated by the modified Simpson Dyskinesia Scale as having mild tardive dyskinesia on at least two consecutive ratings 3 months apart. Although there was uncertainty about whether clozapine definitely caused the tardive dyskinesia in those two patients, a survival analysis comparing the clozapine-treated group with the neuroleptic-treated group showed a lower risk of tardive dyskinesia developing in the clozapine-treated group.
  
  
  CONCLUSIONS
  This study was unable to definitively conclude whether clozapine causes tardive dyskinesia. However, if cases do develop, the risk of tardive dyskinesia is likely to be less with clozapine than with typical neuroleptics.
authors.affiliation: Department of Psychiatry, Hillside Hospital, Long Island Jewish Medical Center, Glen Oaks, N.Y. 11004.
authors.forename: J M
authors.initials: JM
authors.lastname: Kane
authors.forename: M G
authors.initials: MG
authors.lastname: Woerner
authors.forename: S
authors.initials: S
authors.lastname: Pollack
authors.forename: A Z
authors.initials: AZ
authors.lastname: Safferman
authors.forename: J A
authors.initials: JA
authors.lastname: Lieberman
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000009:adverse effects; D003024:Clozapine / Q000009:adverse effects*; D004409:Dyskinesia, Drug-Induced / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D011446:Prospective Studies; D011618:Psychotic Disorders / Q000188:drug therapy; D012559:Schizophrenia / Q000188:drug therapy
chemical_list: D014150:Antipsychotic Agents; D003024:Clozapine