Prospective data on the prevalence of abnormal involuntary movements among elderly people living in the community.

Trained raters from the Liverpool Continuing Health in the Community study interviewed 1070 people over the age of 65 in 1982-1983 using the Geriatric Mental State (GMS) examination. Three years later the cohort was re-interviewed, this time by psychiatrists trained in the GMS, who used the GMS and the History and Aetiology Schedule (HAS). The cohort had fallen in size to 875, because of mortality; 701 were re-interviewed. The cohort was followed up again 6 years after the first interview by trained nurse raters using the GMS (A3) and the Mini-Mental State Examination. Cases of mental disorder identified by the computer diagnostic program AGECAT were re-interviewed by psychiatrists along with a number of controls using the GMS and the HAS on the remaining 450 individuals. Observational behavioural ratings from the GMS and summary sheets were analysed along with AGECAT diagnoses and data on medication gained at the 3 assessments. The community prevalence of tardive dyskinesia and other movement disorders in elderly people over a 6-year follow-up appears to be very low (the community prevalence of tardive dyskinesia being 0.22% and akathisia 1.57%), is usually associated with organic mental disorder (and consequently higher mortality) and is furthermore not usually associated with antipsychotic medication.