DYSKINETIC MOVEMENT DISORDER AMONG ADULTS WITH MENTAL-RETARDATION - PHENOMENOLOGY AND COOCCURRENCE WITH STEREOTYPY

We screened for the occurrence of dyskinetic and stereotypic movement disorders using item-independent screening protocols to determine whet her these forms of movement disorder can be distinguished among adults with mental retardation, Stereotypies and dyskinesias were reliably d istinguished in terms of topography. Tardive dyskinesia occurred in 18 .2% of a cohort of individuals receiving chronic neuroleptic treatment . Stereotypic movement disorder was associated with increased dyskines ia scores and increased prevalence of tardive dyskinesia. Increased dy skinesia scores were also found for subjects exhibiting stereotypy who had been free of neuroleptic treatment for 3 years. Results indicate that dyskinesia and stereotypy are discriminable movement disorders an d provide preliminary support for the hypothesis that they may be rela ted by common mechanisms.