Normal healthy skin has a nice epidermis with a smooth cornified, or outer, layer that acts as a good barrier to water and environmental injury. Skin color and tone is even and unblemished. Components such as collagen (which provides skin firmness), elastin (which supplies skin elasticity and rebound) and glycosaminoglycans or GAGs (which keep the skin hydrated) are all abundant. It is interesting to note that under a microscope a biopsy of a wrinkle exhibits no telltale signs that reveal it to be a wrinkle. So what causes the skin to look wrinkled? It is probably a multi-factorial process of intrinsic aging and extrinsic aging.
Intrinsic aging is the natural aging process that takes place over the years regardless of outside influences. After the age of 20, a person produces about 1 percent less collagen in the skin each year. As a result, the skin becomes thinner and more fragile with age. There is also diminished functioning of the sweat and oil glands, less elastin production, and less GAG formation. Wrinkle formation as a result of intrinsic aging is inevitable, but it will always be slight.
Extrinsic aging occurs in addition to intrinsic aging as a result of sun and environmental damage (tobacco use and exposure to pollution, for example). Extrinsic aging shows up as thickening of the cornified layer, precancerous changes such as lesions called actinic keratosis, skin cancer (including basal cell carcinoma, squamous cell carcinoma, lentigo maligna melanoma), freckle and sun spot formation, and exaggerated loss of collagen, elastin, and GAGs. Alone or in concert, these processes give the skin the appearance of roughness, uneven tone, brown patches, thin skin and deep wrinkles.