The visible signs of skin aging vary from one individual to another. The lucky ones are blessed with youthful looking skin long after others are wrinkled, sagging, and covered with a variety of spots and lesions. Which group one falls into depends on two major factors, genetic heritage, and environmental exposure. Genetic heritage (intrinsic aging) is programmed into our DNA at conception. Environmental exposure (extrinsic aging) is largely the result of choices made. The good news is there are things one can do that affect the visible signs of the aging clock significantly.

The aging clock typically starts ticking in the mid-20s. Deterioration inexorably continues thereafter as collagen production slows and elastin gradually loses its stretch. Skin regenerates at a reduced pace because new cell turnover is depressed. Old skin cells are shed more slowly.

Mirror, Mirror on the Wall

Through the decades, each person observes how the aging process affects them. Intrinsic aging is manifested by the development of fine lines and wrinkles, itchy or dry skin, sagging skin from loss of underlying fat or bone mass, thinning or transparent skin, development of spider and varicose veins and decreased sweat gland production. Smoking, facial expressions, gravity, wind, heat, even the position of sleep contribute to the extrinsic aging process. But none of these is the #1 culprit.

Here Comes the Sun

Remarkably, up to 80% of skin aging may be due to sun exposure. The sun’s rays contribute to wrinkles, freckles, rough skin, loose skin, a blotchy complexion, visible blood vessels on the face, rough red patches called actinic keratoses, and skin cancer. (With that list, it’s hard to understand why anyone would deliberately lay in the sun hour after hour, but they do.)

Ultraviolet light (UVA and UVB) does most of its damage through effects on collagen and elastin in the dermis. UV radiation causes collagen to break down at a higher rate than with just chronologic aging. The damaged fibers are then improperly remodeled which results in disorganized networks called solar scars. An abnormal form of elastin accumulates which exacerbates the problem through its effect on the local enzyme systems involved in rebuilding collagen. Because improper rebuilding degrades dermal structure and support, skin wrinkles. The effects are cumulative. Other deleterious mechanisms triggered by sun exposure are also at work.

Free Radicals

UV radiation is one of the major creators of free radicals. Free radicals are unstable oxygen-containing molecules that are lacking an electron. Because oxygen electrons are more stable when in pairs, the molecule scavenges other molecules for the missing electron. When the second molecule loses an electron to the first molecule, it must then seek another electron, repeating the process. Free radicals contribute to wrinkles by activating the metalloproteinases, a type of enzyme involved in collagen breakdown.

Even more important, free radicals damage the cellular genetic material (RNA and DNA) which can lead to cancers.

The body has a defense system to attack developing cancer cells but when the skin is exposed to sunlight, chemicals are released that suppress these immune defenses. The last line of defense is a process called apoptosis. Apoptosis is a protective cell-suicide which kills severely damaged cells so they cannot become cancerous. The UV exposure is known to prevent this cell death allowing cells to continue to divide – and possibly become cancerous. (So, how important is that suntan now?)

Texture Changes from Sun Exposure

Depending on location, UV exposure can cause thickening or thin of the skin. Thickened, coarse wrinkling with yellow discoloration is called solar elastosis and is common on the back of the neck. Thinning of the skin from UV exposure results in fine wrinkles, easy bruising, even skin tearing.

Blood Vessel Changes Caused by the Sun


UV radiation causes the walls of blood vessels to become thinner leading to bruising with only minor trauma in sun-exposed areas. Most of the bruising that occurs on sun-damaged skin occurs on the backs of the hands and forearms, not on the inside of the upper arm or even the inside of the forearm. The sun also causes the appearance of telangiectasias, tiny blood vessels commonly seen on the face and elsewhere.

Solar Lentigo

Pigment Changes Caused by the Sun
The most noticeable sun-induced pigment change is a freckle or solar lentigo. Light-skinned people tend to freckle more noticeably. Large freckles, also known as age spots or liver spots, can be seen on the backs of the hands, chest, shoulders, arms, and upper back. These are not actually age-related but sun-damage related. UV exposure can also cause white spots especially on the legs, but also on the backs of the hands and arms, as melanocytes are destroyed.

Solar Keratosis

Seborrheic Keratoses

UV radiation causes an increased number of moles in sun-exposed areas. Sun exposure also causes precancerous lesions called actinic keratoses that develop especially on the face, ears, and backs of the hands. These are small crusty bumps that can often be felt easier than they can be seen. Actinic keratoses are considered premalignant because 1 in 100 cases per year will develop into squamous cell carcinoma. UV exposure also causes seborrheic keratoses which are warty looking lesions that appear to be “stuck on” the skin. In contrast to actinic keratoses, seborrheic keratoses do not become cancerous.

Skin Cancer Caused by the Sun


The ability of the sun to cause skin cancer is well-known. The 3 types of skin cancers are melanoma, basal cell carcinoma, and squamous cell carcinoma. Melanoma is the most deadly because it metastasizes more readily than the types. It is believed the amount of exposure of the skin to the sun before the age of 20 is the determining risk factor for melanoma. Basal cell carcinoma is the most common skin cancer and tends to spread locally, not metastasize. Squamous cell carcinoma is the second most common skin cancer and can metastasize although not as commonly as melanoma. The risk of getting basal cell carcinoma or squamous cell carcinoma is determined by a person’s lifetime exposure to UV radiation and the person’s pigment protection.


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