Effect of age on body sway assessed by computerized posturography.

The swaying and postural instability frequently seen in elderly subjects had not been analyzed quantitatively in detail until the introduction of computerized posturography. In order to assess the changes of body sway with aging, we performed computerized posturography in 144 subjects (51 men and 93 women, between the ages of 22 and 88 years) without specific neurological or metabolic disorders. The total and timed track length of the center of gravity, reflecting the distance of sway, increased with advancing age, with a highly significant positive correlation, without marked sex differences. The total area covered by the track of the center of gravity (expressing the extent of sway) also showed a similar tendency. Track density per unit area, expressing the efficiency of postural control, in contrast, decreased with age, showing a significant negative correlation with age, but only when the subjects had their eyes open; this decrease did not occur when they had their eyes closed. The Romberg ratio, an index of exacerbation of sway on eye closure, showed little change with a tendency for slight alleviation of sway and improvement in the efficiency of its control. Computerized posturography appears to be a useful tool with which to analyze the mechanism of swaying associated with old age.