A survey of tardive dyskinesia in psychiatric inpatients in Japan.

To investigate the prevalence of tardive dyskinesia (TD) in a group of psychiatric patients receiving low doses of antipsychotic drugs, we examined 647 Japanese inpatients (361 men and 286 women) with a mean age of 49.8 years, receiving a mean dose of antipsychotic drugs of 276.8 mg of chlorpromazine equivalent. TD was diagnosed according to the criteria of Schooler and Kane with the Abnormal Involuntary Movement Scale. The overall prevalence of TD was 22.3%. Mild TD was found in 67.4% of TD patients, moderate TD in 29.2%, and severe TD in 3.5%. The TD patients were older (59.0 years) than those without this condition (47.2 years). The prevalence of TD increased with advancing age until the 7th decade, when it reached a plateau. The dose of daily antipsychotic drugs was lower in the TD patients (207.6 mg) than in the patients without TD (296.6 mg). The duration of primary illness was longer in the TD patients (28.9 years) than in the patients without TD (20.4 years). Patients receiving antiparkinsonism drugs showed TD less frequently (20.7%) than those not receiving such drugs (31.0%). No significant associations were found between the presence of TD and sex or primary illness.