Onset of dyskinesia and changes in postural task performance during the course of neuroleptic withdrawal

The effect of neuroleptic withdrawal on postural task performance of 20 adults with mental retardation was examined. Dyskinesia was measured using the DISCUS rating scale and postural stability using a force platform during a prospective longitudinal neuroleptic medication withdrawal protocol. Assessments were conducted at baseline and monthly intervals, extending to approximately one year following complete medication withdrawal, when significant changes in amount of postural motion and sequential pattern of postural movement complexity were observed. Postural task performance tended to return to near baseline levels at periods of up to 1 year following medication withdrawal, although one third of the subjects continued to display atypical postural motion profiles at follow-up. Results provide within-subject evidence that tardive dyskinesia is associated with generalized changes in motor control and not simply peripheral disturbances of movement.