Research Diagnoses for Tardive Dyskinesia

To the Editor

—The recent publication by the American Psychiatric Association of its Task Force report on tardive dyskinesia (TD)¹provides a summary of the state of the art in both clinical practice and research-based knowledge that addresses issues of both phenomenology of the disorder and differential diagnosis. However, there has not yet been a systematic effort to reduce the diagnostic heterogeneity that is found within the range of patients who are identified as having TD. The diagnosis reported in the literature frequently represents nothing more than a score on a rating scale. Furthermore, investigators use a variety of terms to modify the primary diagnosis (eg, covert dyskinesia, masked dyskinesia, presumptive TD, withdrawal emergent symptoms, or widhrawal dyskinesia), making communication and comparison of results among investigators difficult.