Topographic subtypes of tardive dyskinesia in schizophrenic patients aged less than 60 years: relationship to demographic, clinical, treatment, and neuropsychological variables.

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Abstract
There are conflicting reports about factors that may be associated with the development of involuntary movements in patients exposed to long-term neuroleptic treatment. Recent evidence suggests that some of these inconsistencies may relate to the practice of regarding these disorders as a unitary syndrome. There is also evidence that both the topographic distribution of these involuntary movements and the pathophysiological mechanisms underlying them may differ in the young and in the old. In this study, demographic, clinical, treatment and neuropsychological variables were investigated for association with the presence of orofacial and limb-truncal dyskinesias in 57 schizophrenic patients aged less than 60 years. Stepwise multiple logistic regression analysis showed that orofacial dyskinesia, at different degrees of severity, was negatively associated with positive schizophrenic syndrome and with either age at assessment or age at onset of illness. None of the indices of schizophrenic deficit (cognitive impairment, clinical defect state, behavioural deterioration, or neurological dysfunction) was related to orofacial dyskinesia. Limb-truncal involuntary movements were negatively related to current daily dosage of neuroleptics. The findings indicate that these two types of dyskinesia may involve different underlying mechanisms and that, for young schizophrenic patients, current pathophysiological or neurochemical theories of involuntary movement disorders are inadequate in explaining their origins.