Factors related to the severity of tardive dyskinesia.

This study was undertaken to clarify factors associated with severity of tardive dyskinesia (TD). It was hypothesized that dopaminergic changes associated with neuroleptic medication may interact with unknown vulnerabilities contributing to the manifestation of TD. Fifty-four psychiatric patients residing on the acute and intermediate care wards of a Veterans Administration hospital participated. Thirty schizophrenic and 24 manic patients, under 60 years of age, were assessed for TD using the Abnormal Involuntary Movement Scale. Cognitive tests were used to form verbal and nonverbal composite indices. The results of multiple regression analyses revealed a modest linear relationship between TD and nonverbal function (p < .03) after controlling for duration of hospitalization, years of illness, motor speed, and age. This relationship was noted for both manic and schizophrenic patients. The results of this study suggest that nonverbal dysfunction is related to severity of TD.