The aging of the skin primarily occurs in the connective tissue, which is almost exclusively composed of collagen fibers. In youthful skin, these are flexible and capable of moving against each other. Due to their swelling capacity, they can retain a lot of moisture.
During the process of skin aging, on the one hand, cell activity continuously decreases, and on the other hand, individual collagen fibers responsible for elasticity, firmness, and moisture retention become hardened and adhere together. The decreasing skin elasticity is accompanied by a reduced water-binding capacity of the epidermis.