Abstract
We investigated the postural control ability during perturbation in the elderly with dementia. Ten elderly with dementia and seven without dementia participated in this study. The perturbation was given randomly with the velocity of 100 mm/s and the amplitude of 50 mm five times. Center of pressure (COP) displacement in the anteroposterior direction and electromyography (EMG) of the tibialis anterior (TA) and the rectus femoris (RF) muscle were measured with the sampling rate of 2000 Hz. The length and the duration of the COP displacement, the latency of the muscle response and %IMEG (0-500 ms and 500-1000 ms after those latencies) of TA and RF were compared between the subjects with dementia and those without dementia. The length of COP displacement and %IEMG TA 500-1000 ms were significantly smaller in the elderly with dementia than those without dementia. On the other hand, the duration of COP displacement, the latency of TA and RF, %IEMG TA and RF 0-500 ms, and %IEMG RF 0-500 ms were not significantly different between those two groups. These results indicated that the subjects with dementia reacted to the perturbation without a delay compared to the subjects without dementia. However, the subjects with dementia kept their balance with the smaller displacement of COP and less contraction of TA compared to the subjects without dementia.
