Tardive dyskinesia: clinical, biological, and pharmacological perspectives.

Tardive dyskinesia is an involuntary movement disorder that usually occurs after long-term neuroleptic treatment. Tardive dyskinesia most often involves the mouth, lips, and tongue and sometimes extends to the limbs or trunk. It is socially embarrassing and can produce significant disability. Prevalence reports range from 0.5 to 56 percent, with a mean reported prevalence of 15 percent in institutionalized patients. Tardive dyskinesia is the most troublesome side effect of long-term neuroleptic therapy, the best available pharmacological treatment for chronic schizophrenia. A variety of pharmacological agents have been investigated as possible treatments for tardive dyskinesia, including agents that decrease central dopaminergic activity, cholinomimetics, and agonists of gamma-aminobutyric acid. Cholinomimetics currently show the greatest potential for improving the symptoms of tardive dyskinesia. New and effective treatments for tardive dyskinesia need to be developed and clinically tested; new antipsychotic agents that do not produce tardive dyskinesia are also needed.