Scientific Journal
Aging and skin aging
The aging or degenerative process of the skin is a natural and inevitable process. This complex and multi-system biological phenomenon, which is influenced by several key factors, is divided into two categories: intrinsic or genetic (Intrinsic) and extrinsic or environmental (Extrinsic): Intrinsic or chronological aging is associated with skin atrophy, decreased elasticity, and decreased metabolic activity. Signs of intrinsic aging include the formation of lines and wrinkles, thinning, discoloration, and loss of skin volume, loss of subcutaneous fat, weakening of the moisture barrier, and dryness of the skin. Genetics, hormonal changes, aging, decreased sebaceous gland activity, dysfunction of fibroblasts that produce extracellular matrix, and oxidative stress resulting from internal metabolism are considered to be the key factors of intrinsic aging. Among them, natural aging is the most important factor of skin aging with internal and intrinsic origins. This process occurs without external interference and influences and follows a predictable pattern, beginning in the third decade of life, becoming more intense and visible in the fourth decade, and reaching its peak in the sixth and seventh decades.
Extrinsic Aging, which is directly related to lifestyle choices and skin care habits, is associated with damage to the skin's connective tissue. Aging caused by external factors that lead to premature skin aging and includes the long-term effects of ultraviolet (UV) light exposure, cellular DNA damage, and decreased collagen and elastin synthesis, is called photoaging. Blue light and infrared (IR) light, air pollution, and the damaging effects of free radicals from environmental factors, tobacco use, cigarettes, and alcoholic beverages, poor diet, stress, anxiety, and lack of sleep are other external and environmental factors that can significantly affect the speed of the appearance of signs of aging and are largely preventable.
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The changes caused by skin aging mainly include two categories of structural changes (structural changes) or microscopic changes and visible changes (visible changes). Structural changes in the skin begin at a relatively early age and are visible in the three layers of the epidermis, dermis and hypodermis. The visible changes in the skin include changes in the skin, connective tissue, muscle and cartilage-bone changes.
A) Structural or Microscopic Changes in Skin Aging:
1. Epidermal Structural Changes:
The epidermis is the outermost layer of the skin that is in direct contact with the external environment and plays a vital role in protecting the skin's defense barrier. During skin aging, significant changes occur in the structure, thickness, cellular activity, and molecular composition of the epidermis, which significantly affect the appearance and function of the skin. A decrease in epidermal thickness, a decrease in the dermal-epidermal junction, a decrease in intercellular lipids (especially ceramides, cholesterol, and free fatty acids), and as a result, a weakening of the skin's defense barrier and an increase in transepidermal water loss or surface evaporation of moisture from the skin (TEWL), changes in Langerhans cells and epidermal immunity, changes in the number and size of melanocytes and skin color, which lead to the appearance of age spots or lentigines, are among the visible and functional consequences of skin aging in the epidermis.
2. Dermal Structural Changes:
The dermis is the middle layer of the skin that plays a vital role in strength, elasticity, nutrition of the epidermis and tissue repair. This layer contains the extracellular matrix consisting of collagen, elastin, glycosaminoglycans (GAGs), reticular tissues and fibroblasts. Changes in the dermis include a decrease in collagen, a decrease in reticular tissues and elastic tissue. Therefore, the skin loses its elasticity and strength and becomes sagging. The decrease in elasticity and strength is especially severe in areas of the skin that are exposed to the sun and is called solar elastosis. In such conditions, the vessels of the dermis become fragile and the likelihood of bruising and subcutaneous bleeding increases. One of the important changes resulting from skin aging in the dermis is a decrease in the sensitivity of skin sensors, which in turn provides the basis for the occurrence of skin trauma. Other findings include a decrease in sebum secretion and atrophy of hair follicles, resulting in unwanted hair loss.
3. Structural Changes in the Hypodermis (Hypodermal Structural Changes):
The hypodermis or subcutaneous tissue is composed of fat cells and connective tissue and plays an important role in maintaining the volume of the skin. The most important finding in the structural changes of the subcutaneous tissue is the reduction in the thickness of the fat layer or atrophy of the adipose tissue, which increases the likelihood of skin injuries and, due to the disruption of the skin insulation system, leads to the dissipation of body heat and increases the likelihood of hypothermia. In addition, the reduction in the thickness and elasticity of the connective tissue also causes the loss of the consistency and strength of the skin structure.
B) Visible changes in the skin aging process:
Visible changes caused by skin aging include skin changes, connective tissue, muscle, and cartilage-bone changes:
Emergence of wrinkles and skin lines: Wrinkles are the most obvious signs of aging and appear mainly in areas of high activity such as the forehead, around the eyes (crow's feet), and nasolabial lines. Dynamic wrinkles are caused by repeated contractions of facial muscles such as frowning or smiling, and static wrinkles are caused by the destruction of collagen and a decrease in skin moisture, and are visible even at rest.
Reduced skin firmness and elasticity: It is caused by the gradual destruction of collagen and elastin fibers in the dermis, leading to sagging, loss of skin strength and elasticity. The appearance of the skin at this stage begins with the formation of fine lines and gradually turns into deeper wrinkles.
Pigmentation changes and pigmentation: This is caused by the dysfunction and activity of melanocyte cells with age. In some areas, the pigments decrease and cause the skin to become pale (Hypopigmentation). On the other hand, in some areas of the skin, brown spots or age spots (Age spots / Lentigines) are created with the increase in pigments.
Changes in the volume and shape of the face: With the depletion of fat in the hypodermic layer (Subcutaneous Fat), the areas of the cheeks, temples and around the eyes appear sunken and drooping eyelids, deep laugh lines and a clear drop in the jawline appear. On the other hand, the decrease in bone density of the jaw and cheeks causes changes in the contour of the face; The face changes from the oval and prominent shape of youth to the square and sunken shape of aging. Sagging skin in the jaw and neck areas is also a result of these changes.
Vascular and skin color changes: As the epidermis thins and connective tissue support decreases, the capillaries and superficial blood vessels of the skin become more visible. This condition is seen as mild redness, telangiectasia (spider veins) or increased vascular transparency. Reduced blood flow and oxygenation cause the skin to look pale, tired and dull.
Dryness and fragility of the skin: Due to the decrease in the secretion of the sebaceous (fat) glands and sweat glands, the surface of the skin loses its natural moisture and fat. The result of this process is dryness, roughness, peeling, open pores and loss of the skin's natural glow. Cell turnover also slows down and the skin takes on a dull and lifeless appearance.
Thinning and reduced skin clarity and radiance: Thinning of the epidermis and dermis makes the skin more sensitive. On the other hand, slowing down the process of epidermal cell renewal and the accumulation of dead cells on the skin surface reduces light reflection and the loss of the skin's natural radiance.
