A statistical trial of subclassification for tardive dyskinesia

Abstract

The authors applied a statistical method to subclassify tardive dyskinesia (TD) in 71 psychiatric patients. Based on two-step statistical procedures and findings reported previously, TD is considered to consist of 2 subgroups: a classical dyskinesic group and a dystonic group. Symptoms manifested in the former group are seen most frequently in the oral region while the latter group, which is usually called tardive dystonia, is manifested by movement disorders in the trunk and extremities, predominantly. Abnormal movements occurring in the facial region characterize a population whose members may belong to either group.

Sub-syndromes of tardive dyskinesia and some clinical correlates

“…We have found evidence of three separate components of TD which closely replicate the findings of Inada et al (1990) and which are in at least partial agreement with other previous reports. Our results differ significantly from Glazer et al (1988) only in the composition of the third factor.…”

“…Glazer et al (1988) also found three subtypes, namely jaw-tongue, face-lips and extremities. These findings were largely replicated by Inada et al (1990). Thus, limb-truncal and orofacial groupings were found, but the orofacial was divided into facial and lips-jaw-tongue.…”

Methamphetamine psychosis in which tardive dystonia was successfully treated with clonazepam

“…2 Inada et al made a statistical distinction between tardive dyskinesia and tardive dystonia. 3 The clinical and physiological backgrounds of tardive dystonia are unclear. However, an existing predisposition to dystonia, which may be triggered by antipsychotics, is likely.…”