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What are the visible signs of intrinsic aging vs extrinsic aging?
So how do you know if what youโre seeing in the mirror is a sign of intrinsic aging vs extrinsic aging? To answer that question, scientists have compared the way photoprotected skinโthink skin thatโs either regularly treated with sunscreen or covered with clothingโages in comparison to skin thatโs been regularly exposed to the sunโs UV rays over a lifetime.Photoprotected skin, which is primarily subject to intrinsic aging, shows signs of aging mostly at the basal layerโone of the deeper layers of the skin. These signs include a thinner epidermal layer from diminished cell production in the basal layer. Other signs of aging skin include reduced collagen production, lower elastin levels, and diminished levels of oligosaccharide, a substance that helps the skin maintain optimal hydration levels. Visibly, these cellular changes show up as thinner, more fragile skin with dryness, loss of firmness, and fine lines. You might notice this type of aging on your body, where your skin has been protected, or on your face if you have mostly avoided the sun throughout your life.Photoexposed skin, which is subject to both intrinsic and extrinsic aging, shows slightly different signs of cellular aging. Unlike the thinner epidermis seen in intrinsically aged skin, photoexposed skin shows signs of thickening in the outermost layer of the epidermis, the stratum corneum. Extrinsically aged skin also shows signs of hyperpigmentation, premature wrinkling, and telangiectasiaโvisible blood vessels on the surface of the skin. For most people, this type of aging shows up as thicker, drier, coarsely wrinkled skin with loss of elasticity and visible dark spots. The most common areas for this type of aging are the face, hands, neck, and chestโareas that have been exposed to the sun chronically over the course of a lifetime. [2]