Influence of age on the wrinkling capacities of skin.
BACKGROUND: Comparisons of clinical assessment with measurement of physical parameters are rare. OBJECTIVE: To standardize the horizontal wrinkling of the skin in order to define a reference chart of the different wrinkling grades and to propose an interpretation of the clinical pattern in terms of skin layers thickness and mechanical parameters. METHODS: A device allowing reproducible wrinkling of the skin was made. The skin folds created in this way were clinically assessed on women of different ages. Measurements of the mechanical properties of the skin were carried out by using a Torquemeter. Skin layers' thicknesses were measured by using in vivo Confocal Microscopy (CM) and Ultrasound Imaging (B mode). RESULTS: Skin wrinkling grades increase versus age. Skin elasticity, extensibility and echogenicity decrease also versus age and the wrinkling grade. Wrinkling appears to be related to skin rigidification (for both stratum corneum and dermis) coupled to a certain weakening of the upper dermis (loss of echogenicity). CONCLUSION: This study points out the key role of the age-related alterations of the upper dermis in skin wrinkling capacities.