Dyskinetic symptoms in profoundly retarded residents following neuroleptic withdrawal and during methylphenidate treatment.

This is a between-groups comparison of chronic drug therapy in profoundly retarded residents. One group of residents received maintenance antipsychotic medication before the study, whereas the control group had been drug-free. Both groups were assessed for dyskinetic symptoms at ten weekly intervals as dosage was phased out in the neuroleptic group. During weeks seven to nine, a double blind, placebo controlled, crossover trial of methylphenidate (Ritalin) took place. Although the original purpose of this was to determine whether methylphenidate helped to suppress chronic behaviour problems, its effects on dyskinetic symptoms were studied as well. Dyskinetic symptoms were marginally higher within the neuroleptic group but they increased strikingly over time irrespective of group membership. Drug consumption, expressed in terms of chlorpromazine equivalents and effect on the dopamine system, was found to be associated with total dyskinetic symptoms at one of two follow-up intervals. Methylphenidate caused a significant increase in dyskinesia scores but this occurred on a minority of subscales.