Correlations between kinematic and rating scale measures of tardive dyskinesia in a developmentally disabled...

This paper reports a study that examines the relations between Dyskinesia Identification System: Condensed User Scale (DISCUS) scores and a battery of postural and movement kinematic measures in a group of adults diagnosed as being developmentally disabled and screened as having tardive dyskinesia. The results showed that finger tremor measures correlated with the tongue tremor and pill rolling items of DISCUS, whereas the postural stability scores correlated with the toe movement item of DISCUS and the total DISCUS score. There was also a high stability in subject kinematic performance from trial to trial over the postural and movement tests. The pattern of correlations between the DISCUS items and movement kinematic measures is consistent with the proposition that tremor is a centrally rather than peripherally driven phenomenon, although many factors contribute to emergent tremors. These findings provide construct and content validity for the DISCUS as a screening device for tardive dyskinesia and suggest that certain posture and movement kinematic measures could be sensitive measuring methods for tardive dyskinesia in developmentally disabled populations.