Tardive dyskinesia and positive and negative symptoms of schizophrenia. A study using instrumental measures.

Background: Controversy surrounds the relationship between tardive dyskinesia (TD) and symptoms of schizophrenia. While some studies reported that negative symptoms of schizophrenia may be a risk factor for TD, others reported a relationship between TD and positive symptoms.

Method: Eighty-four patients were studied, of whom 47 met criteria for TD. Clinical and instrumental procedures were used to increase the sensitivity of our assessments of the presence and severity of TD. Stepwise logistic and linear regression procedures were used to identify demographic variables, psychopathology, and motor parameters associated with the presence and severity of TD.

Results: A 3-factor model consisting of age, clinical tremor, and negative symptoms explained 25% of the variance in clinical TD severity. A 6-factor model consisting of female gender, instrumental and clinical measures of parkinsonism, positive, and negative symptoms explained 49% of the variance in severity of instrumentally derived dyskinesia.

Conclusions: These results suggest that the presence of TD may be associated with positive symptoms; that the severity of TD may be related to negative symptoms; and that the relationship between negative symptoms and TD severity may be influenced by the presence of parkinsonism.