Calcium channel blockers and vitamin E for tardive dyskinesia in adults with mental retardation

Tardive dyskinesia (TD) is one of the major problems associated with the long-term use of neuroleptic medication in individuals with mental retardation. Although no satisfactory treatment is currently available for TD, there has been a suggestion in the research literature that, in theory, calcium channel blockers and vitamin E may be effective in reducing the symptoms of TD. We assessed the effects of verapamil, a calcium channel blocker, and vitamin E on TD in seven adults with mental retardation in a double-blind, placebo-controlled, cross-over study. Following an open baseline, each subject received placebo, verapamil (80 mg/qid), and vitamin E (400 IU/tid) in random order, with each phase lasting 8 weeks. The subjects were rated on the Abnormal Involuntary Movement Scale (AIMS) and the Dyskinesia Identification System: Condensed User Scale (DISCUS) by trained raters. The maintenance medication for all subjects was kept constant during the course of the study. Results showed that although some subjects had a reduction in their TD ratings neither verapamil nor vitamin E produced clinically or statistically significant changes when compared to placebo and baseline conditions. However, the changes associated with vitamin E were promising enough to warrant further investigation of this agent in the treatment of TD in individuals with mental retardation.