What lies behind the PP(-) skin typology?

The first letter "P" indicates that skin ageing is well established. On mature skin, after the age of fifty, expression lines that appeared earlier (crow's feet at the corners of the eyes, frown lines...) become increasingly pronounced, with a loss of firmness at their root. Cellular degeneration continues, coupled with a reduction in the number and size of fat cells in the fatty tissue of the hypodermis, the deepest layer of the skin. This reduction leads to a loss of volume and firmness, which will hollow out the cheeks.

Furthermore, in women, at the time of menopause, deficiencies in oestrogen and progesterone exacerbate the chronological ageing of the skin. Indeed, oestrogens stimulated keratinocytes, the synthesis of hyaluronic acid and collagen, and inhibited the growth of hair follicles. However, with this abrupt drop in the secretion of female hormones, we observe an increased skin dryness, a modification of the barrier function and a loss of radiance.

The letter "P" signifies that the skin is well protected against the sun's UV rays. Beyond these beneficial effects on mood or vitamin D secretion, excessive sun exposure is the main cause of premature skin ageing and the onset of skin cancers. Indeed, UVA rays can cause dermal changes especially in the elastic tissue, and UVB rays lead to epidermal damage. Activation of free radicals, alteration of the cell membrane, DNA modification... UV rays act differently within skin cells to generate damage, which can alter the cell's function, cause its death or provoke DNA mutations leading in the long term to the formation of cancerous cells. Thus, even though the skin has some defences against UV rays (melanogenesis, endogenous antioxidant system...), it is important to regularly apply a sufficient amount of a sunscreen product that is suitable for your skin type and sun exposure conditions, to ensure reasonable exposure while limiting risks.