A statistical trial of subclassification for tardive dyskinesia.

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.