Postural control in the elderly

Abstract

In order to investigate postural control in the elderly, a stabilometric investigation including fast Fourier Transform (FFT) analysis was conducted in three different age groups. The oldest group was composed of 16 subjects who ranged in age from 75 to 86 years: another group consisted of eight 65 to 74 year olds; the control group was composed of 21 young students. The subject was instructed to stand and look for 30 seconds at a spot in a CRT 50 cm ahead of his eyes, and to control body sway as indicated by the gravitational spot in the CRT. The subject was then told to stand with eyes closed for 30 seconds. Next, a 100 Hz vibratory stimulation was applied to the bilateral Achilles tendon in each trial. The data was filtered with a 10 Hz high cut filter and digitized at 25 Hz, and subsequently analyzed by a microcomputer (PC9801 VM 2). Thus, statistical analysis was performed in terms of area, length, and total frequency spectra from 0.10 Hz to 10.0 Hz in both lateral and antero-posterior directions. Sixteen power spectra of 0.249 Hz step from 0.10 to 3.96 Hz were demonstrated in the CRT and were also compared with those of the young group. When standing naturally, significant increases in body sway were found in terms of area, length, and total frequency spectra in the most elderly group as compared with the other two groups. There was no significant change in Romberg ratio between the elderly and the young groups. However, FFT analysis confirmed the influence of visual cues. When vibration was applied, no increases in body sway with regard to these parameters were demonstrated in the elderly, whereas significant increases were found in the young control group. This was especially evident in the eyes-closed trials, as previously reported. There were few increased frequency ranges in either lateral or antero-posterior sway in the elderly. This might suggest that proprioceptive afferent information play a less important role in elderly than in young subjects. When the subject was requested to minimize his own sway by utilizing visual feedback, no difference was found in this parameter between the elderly and young groups. However, FFT analysis of the elderly group revealed an increase of the power spectra close to 1.0 Hz in both lateral and antero-posterior sway, whereas increases of approximately 1.0 and 2.0 Hz in the power spectra and a decrease in the power spectrum from 0.10 to 0.29 Hz were found in both directions in young subjects.(ABSTRACT TRUNCATED AT 400 WORDS)