Age and Hydration dependence of jowl and forearm skin firmness in young and mature women

Background: Quantitative assessment of possible linkages between skin's firmness and water content is useful for cosmetic and clinical purposes and to better understand features of advancing age. Objectives: Our goals were to characterize age-related differential features in skin firmness in women and determine the relationship between skin firmness and indices of skin water. Methods: Skin firmness was quantified using handheld devices that measure the force to indent skin 0.3 and 1.3 mm (F0.3 and F1.3). Skin hydration was quantified using handheld devices that measured tissue dielectric constant (TDC) at 300 MHz to skin depths of 0.5 and 2.0-2.5 mm. All parameters were measured bilaterally in the jowl area and volar forearm of 60 women grouped by age <45 years (YOUNG) and ≥45 years old (MATURE). Results: All measured parameters were bilaterally symmetrical at jowl and forearm. Forearm and jowl indentation forces were greater in YOUNG with statistically significant declines with advancing age with regression relations most evident at shallower indentation depths (P <.001). Quantitative relations for arm and jowl were F 0.3 = 0.256 × AGE + 32.7 mN and F 0.3 = −0.07 × AGE + 17.7 mN. Firmness was related to TDC values only when indentation force and TDC were assessed on the arm at the shallowest skin depths, as weakly related to firmness and was observed to change with age only when measured to a depth of 0.5 mm represented by TDC5 = 0.096 × AGE + 32.7. Conclusions: Experimental finding show clear differences in skin firmness between age-groups with skin hydration playing a minor role. Possible explanations and suggestions for further studies are provided.