Drug-induced movement disorders in institutionalised adults with mental retardation: clinical characteristics and risk factors.

Fifty-three institutionalised adults with mental retardation, the majority (73.5%) moderate to severe, were examined for drug-induced movement disorders. Using a global AIMS score of 2 or more, 16 (34%) of the 47 subjects who had been exposed to neuroleptics had tardive dyskinesia (TD). Three of these had developed the dyskinesia upon withdrawal of neuroleptics. The dyskinetic movements were mainly seen in the lingual, perioral and other facial muscles. Two (33%) out of 6 subjects with no history of exposure to neuroleptics also had similar dyskinetic movements. The total neuroleptic dose significantly, and age marginally, but not sex, brain damage or level of mental retardation, emerged as risk factors for TD. Two (3.7%) subjects had definite akathisia and 16 (30.8%) significant extrapyramidal side effects. This study supports the findings of previous studies of considerable neurological adverse effects of neuroleptics in this patient group and cautions against their injudicious use. It provides further evidence for some putative risk factors for TD and is noteworthy for its lack of support for the contentious issue of brain damage as a risk factor.