Epidemiology of tardive dyskinesia: is risk declining with modern antipsychotics?

Second-generation antipsychotic drugs (APDs), including aripiprazole, clozapine, olanzapine, risperidone, quetiapine, and ziprasidone dominate outpatient and inpatient clinical practice, having largely displaced the older neuroleptics. Modern APDs have relatively low risk for acute extrapyramidal syndromes characteristic of older neuroleptics, particularly acute dystonia and Parkinsonism, with variable risks of akathisia and the rare neuroleptic malignant syndrome. Anticipated reduction in risk of tardive dyskinesia (TD) is less well documented. Nearly 50 years after initial reports on TD, it is appropriate to reexamine the epidemiology of this potentially severe late adverse effect of long-term APD treatment in light of current research and practice. We compared recent estimates of incidence and prevalence of TD identified with some modern APDs to the epidemiology of TD in the earlier neuroleptic era. Such comparisons are confounded by complex modern APD regimens, uncommon exposure limited to a single modern APD, effects of previous exposure to typical neuroleptics, and neurological assessments that are rarely prospective or systematic. Available evidence suggests that the risk of TD may be declining, but longitudinal studies of patients never treated with traditional neuroleptics and exposed to only a single modern APD are required to quantify TD risks with specific drugs. Long-term use of APDs should continue to be based on research-supported indications, with regular specific examination for emerging TD.