QUANTIFICATION OF POSTURAL SWAY PATTERNS IN TARDIVE-DYSKINESIA

An assessment was made of the orientation and variability in postural center of pressure patterns in individuals with tardive dyskinesia (TD ) and/or developmental disability during quiet standing. Postural patt erns were compared and contrasted between four groups of individuals: those with (a) TD and developmentally disabled (severely and profoundl y retarded); (b) developmental disability only; (c) TD but of normal i ntelligence; and (d) a healthy control group. The center of pressure d isplacements were derived from the lateral, vertical, and anterior-pos terior force and moment components of force platform measurements. Ana lyses demonstrated that individuals with TD in combination with develo pmental disability had a different center of pressure orientation and variability compared to healthy individuals and individuals suffering only from developmental disability or TD. The center of pressure patte rn in the developmentally disabled TD group was characterized by a mor e prominent lateral orientation, whereas in the other three groups, it had a more predominant anterior-posterior orientation. In addition, t he variability in these orientation components was much smaller in the developmentally disabled TD group, indicating a more regular pattern of sway in the center of pressure during quiet standing in these indiv iduals. These findings show that assessments of postural center of pre ssure profile orientation and variability may be useful indicators for investigating TD, especially in distinguishing between developmental disability and TD.