What is ageing skin?
Ageing skin describes the changes in the appearance and characteristics of the skin that occur as people get older. Ageing changes are particularly pronounced on the face and hands.
Who gets prematurely aged skin?
Skin appears prematurely aged in people that are chronically exposed to sunlight, a process known as sun damage or photoageing. People with marked signs of photoageing:
- Often live in the tropics or subtropics
- May live at high altitude
- Usually work outdoors or spend long periods outdoors for recreation
- Have sometimes been exposed to artificial sources of ultraviolet radiation (UV), such as indoor tanning
- Often have fair skin (skin skin phototypes I and II), with blond hair and blue eyes
- Rarely have a genetic predisposition to premature ageing (most marked in progeria )
Premature ageing of the skin also affects tobacco smokers and those chronically exposed to other environmental pollutants.
What causes the skin to age?
Intrinsic ageing of the skin is inevitable, and is genetically predetermined. It occurs because of accumulation of reactive oxygen species, biological aging of cells, and reduced cellular supply of nutrients and oxygen.
- The rate of epidermal cell proliferation slows, affecting structure and function of the skin. The skin thins and flattens, with less resistance to shearing forces and injury.
- Water content in the stratum corneum reduces, with less transepidermal water loss.
- Hair thins and greys.
- The numbers of melanocytes reduce.
- Sebum production reduces.
- The dermis has reduced vascularity.
- There are fewer dermal mast cells and fibroblasts, and reduced glycosaminoglycans, hyaluronic acid and ground substance.
- There is reduced collagen and elastin turnover, and increased glycation.
- Volume of subcutaneous fat diminishes, especially on face hands and feet—whereas, it increases on thighs, waist and abdomen.
- Ageing is immune suppressing, leading to increased risk of skin cancer.
Menopause in females
In women, loss of oestrogen levels at menopause contribute to premature aging, as compared with similarly aged men.
Photoageing is due to damage caused by solar radiation. Cell damage occurs because of the formation of reactive oxygen species.
- High energy, short wavelength UVB damages DNA and other components of the epidermis.
- Longer-wavelength UVA is 100 times more prevalent than UVB at the earth’s surface, but is of lower energy, so is less damaging to DNA. UVA penetrates more deeply into the dermis, damaging elastic tissue, collagen, blood vessels and immune cells.
- Infrared radiation penetrates to the deeper dermis and subcutaneous tissue, where it may also contribute to sun damage.
Smoking exposes the skin to several damaging factors.
- Nicotine narrows blood vessels, reducing blood flow, and thus impairs oxygen and important nutrients reaching the cells.
- Many other chemicals in tobacco smoke increase dermal matrix metalloproteinases, degrading collagen and elastin.
- The heat from burning cigarettes, and facial muscle movements associated with smoking, contribute to wrinkles.
- Nitrosamines and tar are carcinogens.
Immune dysfunction also affects skin ageing. Examples include:
What are the clinical features of ageing skin?
- Ageing skin is thin and inelastic, tearing easily.
- It recovers more slowly from mechanical depression than younger skin.
- Women have thinner skin then men.
- Skin is dry, especially after frequent washing with soap and water.
- Dry skin increases the risk of asteatotic eczema
- The barrier function of the skin is less effective than when younger
- Pigmentation is uneven due to melanocyte activation (melanosis) and inactivation (guttate hypomelanosis)
In those genetically predisposed, ageing skin develops:
Photoageing results in:
- Fine lines and wrinkles
- Textural changes
- Thin skin that easily blisters, tears and grazes
- Solar elastosis/heliosis
- Solar lentigos and freckles
- Solar comedones and colloid milia
- Senile/solar purpura
- Scarring, eg from sunburn
- Actinic keratoses (tender dry spots)
- Skin cancer (destructive growths)
Compared to non-smokers of the same age, long-term smokers have:
- More facial lines
- Baggy eyelids and jawline
- Yellowish sallow complexion
- Open and closed comedones and cysts (Favre-Racouchot syndrome )
- Greater risk of skin cancer
Complications of ageing skin
Ageing skin is prone to keratinocytic skin cancer and some types of melanoma. The most common form of skin cancer is basal cell carcinoma. However, excessively photoaged skin is at increased risk of intraepidermal carcinoma, squamous cell carcinoma, lentiginous forms of melanoma, and rare forms of skin cancer such as merkel cell carcinoma.
How are signs of ageing skin diagnosed?
The features of ageing skin are diagnosed clinically. Lesions suspicious of skin cancer may be growing lumps or sores that fail to heal. They often undergo diagnostic biopsy before or as part of treatment.
Classification of photoageing
Glogau classified the degree of sun damage by its clinical signs.
Type I, mild, "no wrinkles"
- Mild pigment changes
- Minimal wrinkles
- No keratoses
Type II, moderate, "wrinkles in motion"
- Appearance of lines only when face moves
- Early lentigines
- Skin pores more prominent
- Early changes in skin texture
Type III, advanced, "wrinkles at rest"
- Prominent pigmentation
- Noticeable solar lentigines
- Prominent small blood vessels
- Wrinkles present when face at rest
Type IV, severe, "only wrinkles."
- Wrinkles at rest or moving
- Yellow-gray skin color
- Prior skin cancers
- Actinic keratoses
How are the signs of ageing treated?
Cancer and precancerous lesions
- Actinic keratoses and intraepidermal carcinomas are most often removed by cryotherapy or treated topically.
- Basal cell carcinoma (BCC) is most often removed by minor surgery, but superficial BCC can be treated topically or by cryotherapy.
- Squamous cell carcinoma (SCC) and melanoma are nearly always surgically excised.
Dry and discoloured skin
Moisturisers will help improve dry and flaky skin.
Alpha-hydroxy acids, vitamin C, lipoic acid, soy isoflavones or retinoid creams applied regularly long term reduce dryness. They may also reduce the number of fine wrinkles and even out pigmentation. Many other products are under investigation but their benefits are unclear.
Procedures that aim to rejuvenate photoaged skin include:
- Fillers (hyaluronic acid, polytetrafluoroethylene, fat grafts) to disguise facial expression lines
- Botulinum toxin injections to reduce frowning and lessen deep furrows.
- Vascular laser treatment and sclerotherapy to remove facial veins and angiomas
- Resurfacing procedures (dermabrasion, chemical peels, and laser resurfacing)
- Cosmetic surgery to remove redundant sagging skin, eg, surgical or laser blepharoplasty for baggy eyelids, meloplasty (face lift) to tighten jowls
How can the signs of ageing skin be prevented?
Intrinsic ageing is inevitable. In perimenopausal women, systemic hormone replacement may delay skin thinning; the skin is less dry, with fewer wrinkles, and wound healing is faster than prior to treatment. Replacement is less effective at improving skin ageing in the postmenopausal decades. The effects of topical oestrogens, phyto-oestrogens and progestins are under investigation.
Protection from solar UV is essential at all ages.
- Be aware of daily UV index levels, eg in New Zealand, adhere to Sun Protection Alert advice.
- Avoid outdoor activities during the middle of the day.
- Wear sun-protective clothing: broad-brimmed hat, long sleeves and trousers/skirts.
- Apply very high sun-protection factor, broad-spectrum sunscreens to exposed skin.
Do not smoke and where possible, avoid exposure to pollutants. Take plenty of exercise—active people appear younger than inactive people. Eat fruit and vegetables daily to provide natural antioxidants.
Many oral supplements with antioxidant and anti-inflammatory properties have been advocated to retard skin ageing and to improve skin health. They include carotenoids, polyphenols, chlorophyll, aloe vera, vitamins B, C and E, red ginseng, squalene, and omega-3 fatty acids. Their role is unclear.