Tardive Dyskinesia - Epidemiology

Epidemiology

Tardive dyskinesia most commonly occurs in patients with psychiatric conditions who are treated with antipsychotic medications for many years. The average prevalence rate has been estimated to be around 30% for individuals taking antipsychotic medication, such as that used to treat schizophrenia. A study being conducted at the Yale University School of Medicine has estimated that "32% of patients develop persistent tics after 5 years on major tranquilizers, 57% by 15 years, and 68% by 25 years." More drastic data was found during a longitudinal study conducted on individuals 45 years of age and older who were taking antipsychotic drugs. According to this research study, 26% of patients developed tardive dyskinesia after just one year on the medication. Another 60% of this at-risk group developed the disorder after 3 years, and 23% developed severe cases of tardive dyskinesia within 3 years. According to these estimates, the majority of patients will eventually develop the disorder if they remain on the drugs long enough.

Elderly patients are more prone to develop tardive dyskinesia, and elderly women are more at-risk than elderly men. The risk is much lower for younger men and women, and also more equal across the sexes. Patients who have undergone electro-convulsive therapy or have a history of diabetes or alcohol abuse also have a higher risk of developing tardive dyskinesia.

Several studies have recently been conducted comparing the prevalence rate of tardive dyskinesia with second generation, or more modern, antipsychotic drugs to that of first generation drugs. Some of these studies claim that the newer, second generation antipsychotic drugs have a reduced potential for causing tardive dyskinesia. Conversely, other studies dispute these claims and report that the prevalence rate has not significantly decreased with the use of more expensive antipsychotic medication.

A physician can evaluate and diagnose a patient with tardive dyskinesia by conducting a systematic examination. The physician should ask the patient to relax, and look for symptoms like facial grimacing, eye or lip movements, tics, respiratory irregularities, and tongue movements. In some cases, patients experience nutritional problems, so a physician can also look for a gain or loss in weight.

Tardive dyskinesia can be socially disabling, perhaps in addition to the underlying psychiatric disorder, and may cause inflicted patients to isolate themselves. Stressful events can also trigger the onset of dyskinetic movements, whereas relaxation and sedation reduce the severity of symptoms in patients.