To the Editor: In the era of typical antipsychotic medications, tardive dyskinesia was a common and often undiagnosed disorder +(1). The newer atypical antipsychotic medications hold the promise of a lower prevalence of movement disorders. We conducted a study whose goal was to determine if this promise has translated from the systematic research to a naturalistic sample.

Evaluations were completed for 162 patients from Central State Hospital in Petersburg, Va. The sample consisted of chronically ill, treatment-resistant adult patients, most of whom had psychotic disorders (70%) or bipolar disorder (9%) based on DSM-IV criteria. The majority (94%) of patients were taking antipsychotic medication. Of this subset, 25% were taking a typical antipsychotic but not an atypical antipsychotic, 52% were taking an atypical antipsychotic but not a typical antipsychotic, and 23% were taking both. Each patient was rated with the Involuntary Movement Scale +(2). The primary rater (D.E.R.) was trained by the developers of this scale and achieved a high level of reliability with respect to gold standard ratings (intraclass correlation coefficient [ICC]=0.96 for parkinsonism global rating, p<0.001; ICC=0.79 for dyskinesia global rating, p<0.001). A diagnosis of parkinsonism was defined as having a rating of 2 (mild) or higher on the global rating scale. Tardive dyskinesia was diagnosed by the criteria of Schooler and Kane +(3).

Per hospital policy, almost all of these patients had a previous examination for dyskinesia by their attending physician with the Abnormal Involuntary Movement Scale +(4). These data were used to compare the prevalence of diagnoses of tardive dyskinesia between the attending physicians and the authors of the current study.

Tardive dyskinesia was present in 40% of the patients (40% of the patients taking only typical antipsychotics, 39% of the patients taking only atypical antipsychotics, and 47% of the patients taking typical and atypical antipsychotics). Of the patients with tardive dyskinesia, 57% had not been diagnosed previously with tardive dyskinesia. Of the patients newly diagnosed with tardive dyskinesia, 48% were mildly ill, 48% were moderately ill, and 4% were severely ill.

For patients taking any antipsychotic medication, 49% had parkinsonism (67% of the patients taking only typical antipsychotics, 34% of the patients taking only atypical antipsychotics, and 68% of the patients taking typical and atypical antipsychotics). Parkinsonism was uncommonly mentioned as an adverse effect, and no rating scale was used by the attending physicians to assess parkinsonism.

A substantial number of patients had tardive dyskinesia or parkinsonism. The high prevalence of newly diagnosed cases of tardive dyskinesia suggests a continuing need for better identification of these disorders and the opportunity for further preventing or treating these disorders.