Ageing reduces skin wetness sensitivity across the body

Humans use sensory integration mechanisms to sense skin wetness based on thermaland mechanical cues. Ageing impairs the skin’s thermal and tactile sensitivity, yet welack evidence on whether wetness sensing also changes with ageing.We mapped localskin wetness and temperature sensitivity in response to cold-, neutral- and warmwetstimuli applied to the forehead, neck, lower back, dorsal foot, index finger andthumb, in 10 Younger (22.4 ± 1.1 years) and 10 Older (58.2 ± 5.1 years) males. Wemeasured local skin temperature and conductance (i.e., a marker of hydration status)at the tested sites, to establish the role of skin’s thermal and mechanical parameters inageing-induced changes in wetness sensing. Irrespective of body site, Older reportedoverall lower wetness perceptions than Younger across all wet-stimulus temperatures(mean difference: −14.6 mm; 95% CI: −4.3, −24.9; P = 0.008; ∼15% difference).Whenconsidering regional wetness sensitivity, the effect of ageing was more pronouncedin response to the cold-wet stimulus over the lover back (mean difference Older vs.Younger: −36.8 mm; 95% CI: −68.4, −5.2; P = 0.014; ∼37% difference) and dorsal foot(mean difference: −37.1 mm; 95% CI: −68.7, −5.5; P = 0.013; ∼37% difference). Wefound no differences between age groups on overall thermal sensations (P = 0.744)nor local skin temperature (P = 0.372); however, we found that Older presented overalllower skin conductance than Younger (mean difference: −1.56 μS; 95% CI: −0.49,−2.62; P = 0.005), which corresponded to an ∼78% reduction in skin hydration. Weconclude that skin wetness sensing decreaseswith ageing primarily due to age-inducedchanges in skin mechanics and tactile sensitivity.