"Positive" and "negative" movement disorders in schizophrenia

Investigations aimed at identifying the clinical characteristics that discriminate tardive dyskinesia (TD) from non-TD patients have yielded disparate findings. We have suggested, based on pharmacological and neuroradiological studies, that TD in schizophrenia may be a covariate of positive symptoms while drug-induced parkinsonism (DIP) may relate to negative symptoms. To investigate this hypothesis, we examined in 47 institutionalized schizophrenic patients the relationship of TD and DIP with psychopathology clusters rated on the Positive and Negative Syndrome Scale. We found that involuntary movements of TD were significantly associated with the activation cluster (p < .01), whereas DIP was significantly associated with the anergia cluster (p < .01). These findings thus support the position that TD is a specific facet of the positive syndrome in schizophrenia, while DIP is a specific feature of the negative syndrome. Clinically, the data suggest that schizophrenic patients with predominant positive symptoms may be at increased risk for TD, while those with prominent negative features could be at increased risk for DIP. In analogy with the positive/negative dichotomy, we propose that TD could be regarded as a "positive," while DIP as a "negative" movement disorder.