Factors related to tardive dyskinesia.

The authors found a 31% incidence of tardive dyskinesia among 261 schizophrenic outpatients treated with neuroleptics. Multiple linear logistic regression analysis revealed a higher incidence of tardive dyskinesia among elderly patients, those with longer records of hospitalization, those for whom neuroleptic medication had little therapeutic effect, and those treated with fluphenazine. Patients manifesting tardive dyskinesia tended to have fewer parkinsonian symptoms than those without the disorder, especially when tremors and akathisia were excluded from consideration. Multiple linear regression analysis indicated that brain-damaged patients and male patients were more susceptible to severe forms of the disorder, even though these factors were not implicated in its initial appearance.