A longitudinal study of correlations among tardive dyskinesia, drug- induced parkinsonism, and psychosis

: Tardive dyskinesia (TD) and drug-induced parkinsonism (DIP) have been hypothesized to reflect opposing states of dopamine (DA) function. In this longitudinal study, 57 psychotic inpatients were rated repeatedly for TD, DIP, and psychosis while receiving neuroleptic medication. Cross-sectional correlations among TD, DIP, and psychosis were weak or nonexistent. Factor and cluster analyses found that 13 patients (23%) were classified into groups characterized by the expected negative correlations. Thus, only partial support was found for the hypothesis that TD and DIP represent opposing states of DA function.