Age-related decrease in sensitivity to electrical stimulation is unrelated to skin conductance: an evoked potentials study.

OBJECTIVE

With aging, skin is likely to become less hydrated, thereby increasing its resistance to electrical current. This, rather than sensorial/perceptual differences per se, may be the primary cause of differences between younger and older adults in somatosensorial perception in response to electrical stimuli.

METHODS

To assess whether aging alters the perception of electrical stimulation, we compared the perceived intensity of electrical stimuli in younger and older subjects, considering both setpoint intensities and the actual intensities of the current passing through subjects' skin. This resulted in reliable information about electrical somatosensory perception in both groups at equivalent received amounts of current. Somatosensory evoked potentials (SEPs) enabled the objective evaluation of somatosensitivity in both groups.

RESULTS

At equivalent received intensities, the mean ratings were significantly lower in older than in younger subjects. SEPs confirmed these results, with older adults having longer latencies and reduced amplitudes.

CONCLUSIONS

Our results suggest that age-related decreases in somatosensitivity to electrical stimuli are not due to cutaneous physiological changes.

SIGNIFICANCE

Age-related increases in electrical somatosensorial and pain thresholds seem to be more attributable to dysfunctions of the peripheral and/or central nervous system, than to non-optimal activation of somatosensorial receptors/nerve fibers due to cutaneous physiological changes.