Heterogeneity of tardive dyskinesia. A multivariate analysis

To determine whether tardive dyskinesia (TD) is a single abnormal movement syndrome or multiple syndromes involving different anatomical areas, we examined 228 out-patients diagnosed with TD at the Connecticut Mental Health Center in New Haven. Application of factor analysis to the seven anatomical severity scores of the Abnormal Involuntary Movement Scale yielded three statistically independent factors involving abnormal movements primarily of the jaw-tongue, face-lips, and extremities-trunk. Using logistic regression to predict the severity of these factors, we found that the severity of the orofacial scores was positively associated with age, schizoaffective or affective disorder, and living alone, while severity of non-orofacial movement was positively associated with current neuroleptic dose, non-use of psychiatric medication, and living alone. Our findings suggest that orofacial and non-orofacial dyskinetic movements may involve distinct clinical syndromes of TD, each having a different set of prognostic and, possibly, aetiological determinants.