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.


CONCLUSIONS
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.
Laboratoire de Neurosciences Cognitives et Adaptatives, UMR 7364 - UdS - CNRS, 21 rue Becquerel, 67087 Strasbourg, France. Electronic address: j.kemp@unistra.fr.
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Kemp
Laboratoire de Neurosciences Cognitives et Adaptatives, UMR 7364 - UdS - CNRS, 21 rue Becquerel, 67087 Strasbourg, France.
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Després
Centre d'Investigations Neurocognitives et Neurophysiologiques, UMS 3489 - UdS - CNRS, 21 rue Becquerel, 67087 Strasbourg, France.
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Pebayle
Laboratoire de Neurosciences Cognitives et Adaptatives, UMR 7364 - UdS - CNRS, 21 rue Becquerel, 67087 Strasbourg, France; Centre d'Investigations Neurocognitives et Neurophysiologiques, UMS 3489 - UdS - CNRS, 21 rue Becquerel, 67087 Strasbourg, France.
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Dufour
D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology*; D004558:Electric Stimulation; D005073:Evoked Potentials, Somatosensory; D005260:Female; D005712:Galvanic Skin Response; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000502:physiology; D017288:Pain Threshold / Q000502:physiology*; D055815:Young Adult
Aging; Electrical stimulations; Evoked potentials; Received intensity; Setpoint intensity; Skin conductance; Somatosensitivity