Early versus late onset psychosis and tardive dyskinesia.

Patients with late-onset psychosis (defined as psychosis requiring hospitalization at age 45 or more, n = 20) were compared with early-onset psychosis patients (defined as psychosis requiring hospitalization at age 25 or less, n = 56) for the prevalence of tardive dyskinesia (TD). Late-onset psychosis patients were found to have significantly more TD (p less than 0.01), which was more severe (p less than 0.05) and developed in a relatively shorter period of neuroleptic treatment (p less than 0.001), than patients with early-onset psychosis. In addition, TD patients (irrespective of early or late onset of neuroleptic treatment) were found to show a preponderance of drug-free periods (p less than 0.01) in their past neuroleptic history, more so than non-TD patients. Our findings indicate that late-onset psychosis should be considered to be a risk factor for the development of TD.