Biological determinants and risk factors for tardive dyskinesia in schizophrenia.

Tardive dyskinesia (TD), a neurological side effect of chronic neuroleptic treatment, develops in 20%-30% of psychiatric patients. The biological characteristics that distinguish schizophrenic patients who develop TD from those who fail to develop TD during neuroleptic treatment are currently the subject of intense research. The aim of the present report is to present biological characteristics and risk factors of schizophrenic patients with TD. The findings of the study demonstrate that: (1) the timing of onset of schizophrenia is a biological determinant for the development of severe TD. (2) the mode of onset of schizophrenia and specifically, an insidious onset is a biological risk factor of TD. (3) belligerent behavior may be a risk factor for TD. (4) postmenopausal schizophrenic patients are at increased risk for TD.