Article by experts: Zouboulis et al.
The aging process is closely linked to changes in skin quality and functionality. Previous research has revealed increased stress in aging skin, evidenced by the up-regulation of components of the adrenocorticotropic hormone system. In addition, differences in the expression of molecules related to lipid production and inflammatory response have been identified between young and aged skin. These alterations may contribute to various age-associated skin disorders, such as dryness, roughness and textural changes. Reduced sebum production and stratum corneum hydration are common features of aging skin, influenced by chronic inflammatory processes and hormonal changes. In addition, the skin's ability to recover after irritation is compromised with age, although the use of lipid-containing topical products can improve this response. This study investigates the skin response to mechanical stress in people of different ages and the effectiveness of skin care in skin repair.
The study carried out provides an objective clinical evaluation of skin functions in young and old people, using biophysical measurements and skin surface lipid content as assessment parameters. In addition, the skin response to different levels of mechanical stress, both with and without the application of skin care products, was analyzed. Participants' subjective perceptions of the quality and efficacy of the products used were compared with objective skin measurements.
Significant differences were found in the biophysical skin measurements between the groups evaluated, although the melanin index was an exception. This suggests that skin color did not affect skin barrier function or erythematous response. Regarding the rate of transepidermal water loss (TEWL), no age- or gender-related differences were observed at the beginning of the study. However, after induction of mechanical stress, the older group showed a higher skin barrier recovery capacity compared to the young group. In addition, the young skin failed to restore initial TEWL values until the seventh day of the study, whereas the older group achieved this without the application of skin care products.
In relation to stratum corneum (SC) hydration, significantly higher values were observed in the older group, although this finding contradicts some previous studies. The basal erythematous response was higher in the older group, which could indicate chronic inflammation or basal stress. In addition, the vascular response after mechanical stress was different between the groups, with a more rapid onset of erythema in the young group.The aged skin also showed a higher pH compared to young skin, which may increase susceptibility to fungal infections. However, both groups restored pH levels after induction of mechanical stress, even without the application of skin care products. Regarding skin surface lipids, differences in composition were observed between superficial and deep skin layers, with a lower proportion of squalene in aged skin. In addition, aged skin showed a higher proportion of very long chain fatty acids, indicating higher elongase activity.
In summary, this study provides detailed insight into age-related skin changes and the skin's response to mechanical stress, as well as the influence of skin care products on these processes.The differences between young and aged skin are evident in their biophysical properties and skin surface lipid (CSL) composition. Contrary to expectations, aged skin demonstrated a higher barrier repair capacity than young skin, along with higher hydration levels. It is suggested that the basal "inflammatory tone" manifested by erythema may be related to this reparative capacity. In addition, the strikingly improved skin quality in the older group was associated with elevated concentrations of cholesterol and long-chain fatty acids.
The skin groups reacted differently to external care, supporting the idea of individualized care according to the physical properties and CSL composition of the skin. In addition, it was found that a widely used skin care product did not improve skin quality, suggesting the need to review and replace products with more beneficial options. Finally, a significant correlation was observed between users' subjective perception of the efficacy of external care products and objective biophysical measurements.
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