What causes skin ageing?
We know that skin ageing is a natural process that cannot be changed. Fine lines, wrinkles, sagging and dark spots are some changes in the skin as we grow older. While some of these changes are unavoidable, certain signs of ageing are actually caused by sun damage and can be avoided. Some knowledge of the mechanism of the human ageing process can allow you to be more adept at ways to slow down such effects.
The process of skin aging can be classified into 2 groups: extrinsic ageing and intrinsic ageing. The two processes are biologically different.
Extrinsic skin ageing
This factor includes physical, chemical or environmental factors that the skin is exposed to. A major contributor to extrinsic ageing is UV radiation. Cumulative exposure to the sun in an individual’s lifetime can add up to cause significant damage to the skin.
Other external factors are cigarette smoking, air pollution, and exposure to cold, heat, dust and smog. Our lifestyle choices can also take a toll on our skin e.g. exercise, sleeping habits, diet or stress. Varying circumstances through all these factors can cause oxidative stress. This leads to some extent of dysfunction across our cells, mitochondria, DNA and could manifest as inflammation, cellular membrane damage or even immune dysfunction for instance.
UVA and UVB radiation causes photoageing. As UVA can penetrate deeper into the skin (greater penetration depth) and generate unwanted radicals, it is said to be more responsible for photoageing. UVB rays are mostly absorbed by the outer skin layers and causes DNA damage within the outer skin cells.
Photoageing is a slow process resulting from chronic exposure to UV radiation. Skin type and accumulative lifetime exposure to the sun can determine the degree of photoageing. When UV light penetrates the skin, cells produce melanin to form as a protective barrier (this is also how a tan is developed!). The melanin pigment helps to reflect some of the rays. The rest of the radiation that is not reflected will be absorbed by the skin cells. This can damage the cells that function to develop tissue fibers for the skin’s structure.
In photoaged skin, the epidermis (outermost skin layer) becomes more fragile and less elastic. There is greater damage of elastic tissue and a decrease in cellularity. It can cause elastosis, where there is an overgrowth of elastic fibers. Rough spots called actinic keratoses can also be caused by excessive UV exposure, which can be precancerous skin lesions.
Antioxidant and skin ageing
UV radiation causes oxidative damage. This means it produces excessive free radicals within the skin cells. Free radicals are formed when atoms or molecules loose electrons. They are generated by our own bodies during normal metabolic process, but external sources such as from UV radiation may cause excessive amounts. Excessive free radicals can lead to human skin disorders and premature skin ageing for example. Exposure to air pollutants can also trigger the release of free radicals.
The human skin has antioxidant enzymes to help protect against free radicals, such as superoxide dismutase (SOD) and glutathione (GSH) biosynthesizing enzymes. Other antioxidant molecules you may be familiar with are vitamins A, C and E. Antioxidants protect cells by interacting with the free radicals and neutralizing them by “donating” electrons to prevent unwanted damage.
You can think of the antioxidants as the ‘good’ molecules in your fight against ageing. However, these antioxidants reduce in number over time, thus a weaker ability to combat against free radicals and against ageing. With weaker defence against free radicals, the skin begins to show signs of photoageing.
Intrinsic skin ageing
Intrinsic ageing can also be understood as genetically programmed ageing. Structural proteins such as collagen and elastin, a major component of the dermis, and organelles such as mitochondria are produced less over the course of time. DNA functions and repair abilities decline with time. Thinning and loss of the skin’s elasticity happens as visible manifestations of these changes. Chronologic ageing can also be caused by hormonal changes.
Preventing the ageing process
To improve skin quality, there are various treatments available.
- Sunscreens have been long perceived as a vital prevention measure to reduce UV damage. Look for a dermatologist tested sunscreen with minimum SPF30. Apply and reapply religiously (every 3 hours for optimal protection).
- Retinoids have shown to reverse sun damage and can improve the skin’s extracellular matrix (which provides structural and biochemical support to cells).
- Cosmeceuticals may serve as a ready consistent supply of antioxidants
- Dermal fillers can restore volume loss and remove skin wrinkles
- Chemical peels use acids to regenerate and improve the appearance of aged skin
On your own, certain lifestyle habits can be changed to slow down the process of skin ageing. Adequate exercise and sleep are vital in general regulation of bodily functions which combat aging. Quitting smoking can cut out exposure to unwanted chemicals and pollutants. A diet rich in antioxidants can also be helpful. Keep hydrated and cleanse your skin regularly to remove dirt and pollutants / chemicals (which may cause oxidative stress) from the skin.
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Meet with Dr. Teo Wan Lin, an accredited dermatologist at TWL Specialist Skin & Laser Centre, for a thorough consultation to determine the most suitable treatment for your skin.
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