What happens to our skin as we age?
Our skin is composed of multiple layers, all of which undergo some changes as we grow older. The outermost layer of our skin, the epidermis, is composed of a thick stack of skin cells. These cells are generated at the bottom of the epidermis. As they mature, they migrate toward the surface. The outermost part of the epidermis (the stratum corneum) consists of 25 to 30 layers of dead cells. These cells are eventually sloughed off as new cells push up from below. As we age, new cells form at a slower rate, making our skin thinner. Dead cells are not pushed off and instead pile up on the skin’s surface, making it drier, rougher and duller in appearance.
However, the most significant changes in terms of our skin’s appearance occur in the dermis. This layer is normally thick with connective tissue (mainly collagen, elastin and proteoglycans), which provides much of our skin’s strength and resilience and some of its ability to retain water. With age, the dermis becomes thinner and drier. Instead of being a delicate scaffold, its main structural proteins deteriorate, leaving behind fragmented, thickened and disorganized fibers. These don’t work as well as our better-organized, youthful matrix, either in maintaining the skin’s support structures or providing healthy places for our skin cells to live. Over time, as our support tissues lose their ability to retain tension, our skin becomes less elastic (a condition known as elastosis) and more prone to sagging. Similar changes also lead to wrinkles. Another key component in aging skin is reduced water content. However we might try to condition our skin with moisturizers (this is a good thing), our aging skin gradually loses the ability to retain its state of hydration.
Finally, changes in the tissues underlying our skin also impact significantly on our aging appearance. Although our waistlines tend to expand with age, there is a reduction in the deposits of fat under the skin on our cheeks, shins and the backs of our hands, making our skin look and feel papery. The loss of support tissue leads to sagging, with aging faces looking more ‘squared off’ compared to the angular shapes of youthful faces.
Old under the sun (photo-aging)
When we despair about the onset of lines and wrinkles, roughness and unwanted pigmentation, we need look no further than our time in the sun for its origins. Four out of five wrinkles, and most of the freckles on our faces, are due to sun exposure. Preventing excessive solar damage with the regular use of broad-spectrum, water resistant SPF30+ sunscreen, wide-brimmed hats and protective clothing is the most effective way to slow the aging of our skin.
Exposure to UV, visible and infrared radiation from sunlight results in cumulative changes in the texture, color and quality of our skin (known as photo-aging). This can be appreciated when we compare the leathery, sun-exposed skin at our necklines with the skin on adjacent areas of smooth, unblemished non-exposed skin.
The effects of photo-aging vary from person to person, depending on the duration and intensity of our sun exposure, skin type, genetic legacies and our diet. For example, a low-GI diet rich in vegetables, nuts, legumes and olive oil is associated with reduced rates of skin aging, given the same cumulative exposure to the sun.
By contrast, increased skin aging is seen in those with a high intake of meat, full-fat dairy and butter.
Early signs of sun damage to our skin may be difficult to see in the mirror or by looking at old photos. Imaging under UV light allows clinicians to look at superficial and deep pigments in our skin. An imaging test can give a score relative to our age. Repeat examinations can help track the effectiveness of treatment programs.
Last reviewed 17 November 2012