Aging is a continuous, universal, progressive, intensive, deleterious, but democratic phenomenon, which is essential to the evolutionary process and of which the skin is not an exception. The older we get, the more wrinkled our skin becomes. In the human skin, factors such as age, sun-exposure, smoking, and endocrinological changes are considered to be important risk factors for wrinkles.

Skin Aging

The skin is the largest organ of the body and is a complex organ, which is vitally important to human health. By providing a seal and a barrier from the outside elements, the skin maintains the rest of the body in its own ideal environment thereby making it possible to live and adapt to a number of different environments. Numerous variables determine the skin's quality, particularly the ravages of the external environment and age, which are the most important variables.

Aging is a continuous, universal, progressive, intensive, deleterious, but democratic phenomenon, which is essential to the evolutionary process and of which the skin is not an exception. The older we get, the more wrinkled our skin becomes. In the human skin, factors such as age, sun-exposure, smoking, and endocrinological changes are considered to be important risk factors for wrinkles [1-4].

Concept of skin aging

The skin is a unique organ, which reflects the inevitable changes occurring in the body's aging process. It is the body's dynamic interface with the environment and as such its roles include barrier function, mechanical protection, wound healing, immune surveillance, thermoregulation, and sebum production, to mention a few. All these functions decline with age. Aging of the skin is a complex process, associated with morphological and chemical changes, dictated by an inherent genetic program and accelerated by environmental damage to genes and their protein products. Through structural and molecular degradation, aging causes a functional deficit in the skin resulting in clinical changes, including wrinkling, colour changes (dyspigmentation), laxity and no-elasticity {5, 6}.

Two independent processes govern skin aging, the intrinsic and the extrinsic aging of the skin.

Intrinsic aging

Intrinsic aging, also known as the natural aging process, is the slow irreversible degeneration of tissue, which affects almost all body organs. Usually beginning in our mid-20's, intrinsic aging is a continuous process, which by definition, is inevitable and as such is not subject to manipulation through changes in human behaviour. It is genetically programmed and causes structural and functional changes in all layers of the skin. Although it begins in the mid-20's the signs of intrinsic aging are not usually visible for decades [7-9].

Intrinsic aging produces lines and wrinkles, age spots, splotches and pigmentation problems, broken capillaries, dull skin texture and colour, and other skin flaws. Apart from these, intrinsic aging may cause a previously attractive mole or birth mark to change into an unattractive protrusion or a once unnoticeable scar may become more apparent when wrinkles form around it. The production of collagen within the skin is slowed and elastin, a protein constituting the basic substance of elastic tissue, which enables the skin to snap back into place on pulling, becomes less "springy". Epidermal turnover (turnover of new skin cells), which takes about 28 days in young adults requires about 40-60 days in the elderly. This slower turnover results in a thinning of the epidermis, which gives aged skin a translucent appearance, as well as adversely affecting skin barrier function and repair, and cell exfoliation. Intrinsic aging causes a decrease in subdermal (beneath the skin) fat tissue, which contributes to wrinkling and sagging of the skin, making the skin more susceptible to trauma and bruising. Although it causes a number of structural changes, the effects of intrinsic aging are mostly functional, with only minor impacts on skin appearance (as previously mentioned) - fine wrinkling, dryness, and thinning. The genetic program of intrinsic aging differs in each individual both in terms of rate and severity of effect [8, 10, 11].

Extrinsic aging

Extrinsic aging is generally caused by external factors introduced to the body, such as smoking, excessive alcohol consumption, poor nutrition, pollution, harsh weather and chronic sun exposure (photoaging). Other factors include repetitive facial expressions, gravity and sleeping positions. Of all these external factors, sun exposure is considered to be by far the most significantly harmful to the skin and according to Baumann (2007) 80% of facial aging is believed to be due to chronic sun exposure [8, 9].

1. Sun exposure (Photoaging)

The human skin is exposed to UV and infrared radiation practically everyday and without protection from the sun's rays, a few minutes of exposure each day over the years can cause noticeable changes to the skin as the skin loses the ability to repair itself and as such, the damage accumulates. The clinical manifestation of photoaging depends on skin type, skin colour and the history of long-term or intense sun exposure. An individual with fair skin with a history of sun exposure will develop more signs of photoaging than a dark skinned individual. For individuals with the darkest of skins, the signs of photoaging are often limited to fine wrinkles and complexion marked with spots or blotches of different shades or colours. It has been shown that repeated ultraviolet exposure damages the skin by breaking down collagen, impairing the synthesis of new collagen and attacking elastin, thereby causing immense damage. Photoaging is characterised by coarse, deep, severe wrinkling as well as pigmentary changes on exposed areas such as the face, neck and forearm. Losses in skin tone and elasticity, increased skin fragility, and benign lesions are also observed in skin affected by photoaging [8-10].

2. Cigarette smoking

Cigarette smoking is the second causative factor of premature skin aging after photoaging as it triggers biochemical changes in the body, which accelerate the aging process. It has been shown that individuals who smoke 10 or more cigarettes a day for a minimum of 10 years are statistically more likely to develop deep wrinkled, leathery skin than non smokers. Smoking exerts a noticeable effect on the skin such that it is often possible to detect whether an individual is a smoker or not by simply looking at his or her face. Such individuals have more wrinkles and their skin tends to have a greyish pallor compared with non smokers [8, 12-15]. The most serious damage to the skin through smoking is often caused by the following:

a. reduction in the body's storage of vitamin A, which produces protection from skin damage

b. continual puckering from drawing on a cigarette as well as squinting in reaction to cigarette smoke create deeply wrinkled skin around the eyes and mouth - these are classic signs of "smoker's face"

c. restricted blood flow through the capillaries thereby preventing oxygen and nutrients getting to the skin

d. restriction of the absorption of vitamin C, which is a vital oxidant for skin protection and health

e. acceleration of the decrease in collagen production, an enzyme vital to the skin's elasticity.

(Taken from Lifestyle - Ref 14)

3. Facial Expression/ Facial Animation

Each time facial expressions are made, a facial muscle or facial muscles are used. These cause a groove to form beneath the surface of the skin causing it to form lines with each facial expression. As the skin ages and loses its elasticity, it loses its ability to spring back to its "line-free" state and consequently grooves become permanently etched on the face as fine lines and wrinkles (referred to as expressive wrinkles) [8, 16].

4. Sleeping positions

Continually sleeping by resting the face on a pillow in the same way every night for years on end can lead to the development of wrinkles on the face. These wrinkles (also known as sleep lines) eventually become etched on the surface of the skin and no longer disappear when the head is not resting on the pillow [8].

5. Gravity

Naturally, gravity pulls on our bodies; however, the changes related to gravity become more pronounced with age. When the skin loses its elasticity, the effects of gravity become more evident causing drooping of the eyelids and eyebrows, elongation of the ear lobes, formation of jowls and "double chin", drooping of the tip of the nose, and disappearing of the upper lip whilst the lower lip becomes more pronounced [8, 17].

Prevention of skin aging

Although much cannot be done to halt or reverse the intrinsic aging process, changes associated with extrinsic aging are largely preventable. Preventative measures include,

1. Protection from UV light, which at any age reduces photoaging and decreases the risk of age-related skin diseases. Photoprotective measures include,

¢ Sun avoidance particularly when the sun's rays are the strongest (usually between 10am and 4pm).

¢ Wearing protective clothing (e.g. wide-brimmed hats, long sleeves) when outdoors during the day.

¢ Applying sunscreen. This should be broad spectrum, offering UVA and UVB protection, and should have a sun protection factor (SPF) of 15 or higher.

¢ Avoiding deliberate tanning, including the use of indoor tanning devices.

According to McCullough et al (2006) preventative measures should begin in early childhood since approximately 80% of the damage caused to the skin by the sun is thought to occur by the age of 18 years. McCullough et al (2006) also make mention of the fact that the use of sunscreen is the "gold standard" for protecting the skin from ultraviolet light. It has also been well documented that regular use of a broad spectrum sunscreen can prevent not only sunburn, but also many skin-aging effects, such as wrinkles and pigmentary changes. In association with the implementation of skin-aging treatment, the use of sunscreen and sun protection is also important. It is essential to note that the beneficial effects of skin rejuvenation measures will be minimised or cancelled if unprotected sun exposure continues to induce skin damage [8, 10].

2. The use of antioxidants, which provide another approach for the prevention and treatment of both intrinsic and extrinsic skin aging. The skin has an integrated endogenous antioxidant defence mechanism that scavenges free radicals (which play a pivotal role in the biological events that lead to the clinical manifestations of skin aging) and protects cells from damage. These naturally produced antioxidants are reduced in chronically aged skin and further reduced in sun damaged skin. Taking antioxidants can help augment skin antioxidant levels to enhance defence mechanisms. However, according to McCullough et al (2006) oral supplementation has not been successful in augmenting skin antioxidant levels as a result of physiological processes, which take place in the body. It has however been shown that antioxidants can be delivered via the percutaneous route (through the skin) to directly supplement the skin's antioxidant reservoir. Antioxidants include vitamins A (retinol), C (ascorbic acid), and E (tocopherol), beta-carotene, and bioflavonoid [10, 18].

3. Quitting smoking, desisting from performing facial exercises or expressions and correcting sleeping positions by not lying face down [8].

Rejuvenation of ageing skin (Anti-ageing procedures)

For individuals hoping to look younger or wondering how to look younger, corrective measures for ageing skin are numerous and varied. These include:

1. Topical medications, such as topical retinoids (e.g. tretinoin, tazarotene and adapalene) which are effective in minimising fine lines and wrinkles, as well as improving skin texture and hyperpigmentation [10].

2. Chemical peels, which are quite beneficial in the treatment of wrinkles, skin discolouration and age spots. Depending on the amount of skin damage, a variety of peeling agents are used to produce light, medium or deep chemical peels. On healing, new skin, which is noticeably smoother, fresher and younger in appearance, is generated [11, 18].

3. Botulinum toxin (Botox), a sterile, vacuum-dried purified form of Botulinum toxin type A. It temporarily denervates specific muscles, which are responsible for certain facial wrinkles, including horizontal forehead lines, horizontal neck lines, and crow's feet. It is injected in very tiny amounts into specific muscles to treat and improve lines, wrinkles and furrows associated with facial expression [11, 18].

4. Soft tissue fillers, which involves injecting filling substances under the skin. A variety of filling substances are available and those successfully used in soft tissue augmentation include bovine collagen, silicone, hyaluronic acid, Fibrel®, Goretex®, to mention a few; all these need to be applied by a skilled dermatologist. They are used to "plump up" or contour and correct wrinkles, furrows and hollows in the face [11, 18].

5. Dermabrasion, a traditional technique, which makes use of a special instrument to remove or abrade the upper layers of the skin and smooth out irregularities in the skin surface. Usually performed to correct scarring, but is used by some physicians to perform dermabrasion for substantial sun damaged skin or skin with pigmentation problems [10-11, 18].

6. Microdermabrasion, which uses tiny particles that pass through a vacuum tube to gently scrape away the ageing skin and stimulate new cell growth. Suitable for patients with mild to moderate skin damage and wrinkles [11].

7. Facelift, a well known procedure used to remove sagging and redundant skin in the lower third of the face and under the chin [11].

8. Laser resurfacing, also known as "laser peel" is a relatively new procedure, which uses the newest generation of the carbon dioxide and erbium YAG lasers to remove areas of damaged or wrinkled skin, layer by layer, revealing fresh skin underneath. It is most commonly used to minimise the appearance of fine lines, particularly around the mouth and the eyes. It is also effective in treating facial scars or areas of uneven pigmentation. It is often done in conjunction with another cosmetic operation such as a facelift or eyelid surgery [11, 19].

9. Non-ablative resurfacing: relatively new treatment options used to rejuvenate ageing and sun damaged facial skin. They make use of non-ablative laser and intense pulsed light technologies, including electrosurgical resurfacing using electrical energy at low temperature. Non-ablative techniques were developed as a less destructive alternative to laser resurfacing and chemical peels. When used to treat wrinkles and scars, these techniques allow for rapid healing, as well as improving fine lines, and possibly skin tone [11, 18].

10. Light Therapy, which is essentially the use of infrared LED light therapy. This is used based on the fact that the skin has the ability to absorb infrared light and in the process use it as a source of energy to stimulate cellular regeneration. First researched by NASA for use in the U.S Space Program, infrared LED light therapy can reverse and control the visible signs of ageing without the use of harsh chemical treatments or invasive surgical procedures. Infrared LED light therapy aids in increasing the production of collagen and elastin, thereby improving the skin's tone and elasticity. This form of light therapy is gentle, painless, safe, non-invasive and nonabrasive, and its application feels comfortable and relaxing. So straight-forward is its ease of use that it can be used in the comfort of the home.

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