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 it 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 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, 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.
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 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 protective cell-suicide which kills severely damaged cells so they cannot become cancerous. 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 thinning 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.
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.
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.
Hormone Effects and Wrinkles
It is likely there are skin changes that result from the hormonal effects of menopause and decreased estrogen production. However, studies in humans have not documented which skin changes are specific to decreased estrogen and which skin changes result from sun exposure or normal chronological aging. In animal experiments lack of estrogen can cause a decrease in collagen levels of 2% per year and a decrease in skin thickness of 1% per year.
As it loses elasticity, habitual facial expressions cause the skin to develop wrinkles. Frown lines between the eyebrows and crow’s feet radiating from the corners of the eyes develop as the tiny muscles in those areas permanently contract. (Happy people develop laugh and smile lines.)
Gravity and Wrinkles
The effects of gravity make the loosening of the skin more apparent. This causes jowls and drooping eyelids.
Normal Chronological Changes of the Skin
The number of epidermal cells decreases 10% per decade and rates of cellular division slow, reducing the ability of skin to repair itself. Epidermal cells also become thinner and less sticky. Thinner cells make the skin look noticeably thinner and decreased stickiness reduces the effectiveness of the barrier function, allowing escape of moisture. Sebaceous glands produce less sebum, and the number of sweat glands decreases, both of which also contributes to skin dryness.
The ridges (papillae) of the dermal-epidermal junction flatten, making the skin more fragile and easier to shear. This also decreases the surface area between the two layers, reducing delivery rate and amount of nutrients available to the epidermis, further inhibiting repair.
While sun exposure accelerates the process, reduced collagen and elastin are also age related phenomena. A lax dermis makes skin easier to wrinkle. Because the subcutaneous layer becomes less dense and thinner with age, wrinkles and sagging are more noticeable.
So, What’s a Girl to Do? (This goes for the guys, too.)
All is not lost. Although aging is part of life, an indispensible part as it turns out, there are things to do that can help one’s skin age more “gracefully”. Our final installment on skin will discuss ways to look your best at every age.
As readers of BFT already know, we tell it like it is. Scammers and fraudsters – be forewarned.
P.S. DON’T FORGET TO USE SUNBLOCK !
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