Somesthetic sensitivity in young and elderly humans.

Absolute thresholds were measured on 27 young (ages 19 to 31) and 21 elderly (ages 55 to 84) humans to six modes of cutaneous stimulation (single ramp-and-hold skin indentations--tactile, vibration at 40 and 250 Hz, temperature increases and decreases, and noxious heat) at two sites, the thenar eminence and the plantar foot. Comparisons of the elderly and young groups showed that elderly persons were significantly, p less than or equal to .001, less sensitive than young individuals to mechanical stimuli (tactile and vibration) at both sites. No significant differences were found in thresholds to thermal stimuli (warm-, cold-, and heat-pain) at either site except elderly feet were significantly, p less than or equal to .001, less sensitive than young feet to warm stimuli. Thresholds of elderly individuals were compared with the young group thresholds for deficits in sensitivity. All elderly participants showed deficits to one or more of the stimulus modes at one or the other site. There were significantly, p less than or equal to 0.01, more deficits to mechanical than to thermal stimuli. There was no increase in the frequency of deficits with increasing age.