The Nithsdale schizophrenia survey. V. Follow-up of tardive dyskinesia at 3 1/2 years.

The point-prevalence of tardive dyskinesia in schizophrenics from a discrete geographical area (Nithsdale, in Dumfries and Galloway Region) in 1981, 1982, and 1984 was 31%, 27%, and 30% respectively. This suggests that the prevalence of tardive dyskinesia in a community of schizophrenics has reached a plateau. In 12% of patients there was persistent dyskinesia, i.e. abnormal involuntary movements were present at all three assessments. Persistent dyskinesia was more common in older patients. The severity of tardive dyskinesia fluctuated between assessments in 41% of patients, indicating that it is only a transient feature in some cases.