The effect of vitamin E treatment on tardive dyskinesia and blood superoxide dismutase: a double-blind placebo-controlled trial.

Free radicals may be involved in the pathogenesis of tardive dyskinesia (TD). Vitamin E, a free radical scavenger, has been reported to improve symptoms of TD. The present study was designed to replicate this finding in a group of Chinese patients with TD, and to examine the effect of vitamin E treatment on blood superoxide dismutase (SOD), a critical enzyme in the detoxification of free radicals. Forty-one inpatients with TD completed a double-blind, placebo-controlled, parallel-group study of vitamin E. Twenty-two of the patients were randomly assigned to receive a fixed dose of 1200 IU/d vitamin E, and 19 were assigned to a placebo for 12 weeks. Patients were assessed primarily using the Abnormal Involuntary Movement Scale (AIMS) at baseline, weeks 6 and 12. Blood SOD levels were measured by radioimmunometric assay before and after treatment. The results showed that the reduction in AIMS score from baseline was significantly higher with vitamin E treatment compared with placebo (45.9% vs. 4.3%). Blood SOD levels were significantly increased after treatment with vitamin E (P = 0.001), but no change with placebo treatment (P < 0.05). These results support earlier findings of the efficacy of vitamin E in the treatment of TD. Moreover, the efficacy of vitamin E may be due to its ability to increase SOD level, which may reduce oxidative injure in tardive dyskinesia.