Biological skin aging: types of skin aging

Chronological aging of the skin

There are changes in both the epidermis and the dermal structures. In particular, a decrease in the number of epidermal cell lines, a violation of keratinocyte differentiation, an increase in the size of keratinocytes, a change in the ratio of ceramides and other highly specialized skin lipids, providing barrier properties, including retention of water in the skin. Smoothening is observed in the region of the basal membrane. In the dermis with aging, a decrease in the synthesis of collagen and elastin proteins by fibroblasts is recorded. It is from these proteins in the main substance of the dermis that collagen and elastic fibers are synthesized that provide skin turgor (tone) and elasticity. In addition, a decrease in the number of important components of the main substance of the connective tissue, ensuring the retention of water in the skin (glycosoaminoglycans, chondroitin sulfates, etc.), and microcirculation disorders of the skin.

As a result of the listed morphological changes, clinical signs of chronological aging become noticeable: thinning, dryness, wrinkles (small and deeper) and a decrease in skin turgor, gravitational ptosis of the soft tissues of the face. The listed symptoms are primary, or mandatory; may also occur indirect (secondary). They include edema and facial swelling, especially in the periorbital zone, large-pore skin, facial erythema, telangiectasia, seborrheic keratoses, xanthelasm.

The stage of appearance of signs of skin fading can be represented as follows.

Eye area:

• the appearance at the age of 20-25 years of a network of fine superficial wrinkles in the corners of the eyes;
• the appearance by 30-35 years of the so-called "crow's feet", which are the radial folds in the corners of the eyes;
• change in the condition of the skin of the upper and lower eyelid: the appearance of overhanging folds in the upper eyelid, the lowering of the level eyebrows perceived visually as a narrowing of the eye slits, as well as saccular formations in the lower eyelid region (not due to the pathology of internal organs); ptosis of the upper and lower eyelids is accompanied by the formation of fatty "hernias" of the eyelids, i.e., the swelling of intraorbital fat.

Forehead skin area:

• formation of longitudinal folds ("wrinkles of thinking") in the forehead;
• the appearance of transverse folds in the region of the nose ("wrinkles of concentration").

Area around the mouth:

• deepening of nasolabial folds;
• omission of the corners of the mouth;
• the formation of small transverse folds over the upper lip ("corrugation").

Area of cheeks, neck, ear:

• decrease in turgor, elasticity of the skin and muscle tone in the cheeks and neck, leading to a change in the oval line of the face, omission of the fatty lump;
• the appearance of folds in the bovine and anteroposterior areas, changes in the shape of the auricle due to the sagging of the lobes.

Menopausal skin aging

An important role in the development of aging is occupied by physiological age-related changes in the endocrine sphere, especially those occurring in the body of a woman. After the onset of menopause aging processes are accelerated. There is a decrease in the level of production of estradiol in the ovaries, resulting in the termination of menstruation, hot flashes, rising blood pressure, osteoporosis and other changes. The lack of estrogens significantly affects the various structures in the skin. It is known that the average level of estradiol in the blood plasma during the normal menstrual cycle is about 100 pg / ml, and at the beginning of the menopause it drops sharply to 25 pg / ml. It is the sharp drop in the concentration of estradiol that explains the rapid appearance of signs of menopausal aging of the skin. At the same time, extra-ovarian synthesis of estrone occurs in the subcutaneous adipose tissue from androstenediol by its aromatization. That is why at the stage of extinction of ovarian function this hormone is the dominant estrogen, providing a significant protective effect on the skin, especially in women with excessive body weight.

Biological "targets" for estrogens in the skin are basal keratinocytes, fibroblasts, melanocytes, adipocytes. By the present time, extensive information has been accumulated on changes in the epidermis, in the region of the dermo-epidermal contact, in the dermis, in the subcutaneous adipose cell, and also in the underlying muscles. In the epidermis, a slowdown in the rate of proliferation of basal keratinocytes is detected, which ultimately leads to its atrophy. There was a decrease in the expression of integrins and CD44, which play an important role in the adhesion and differentiation of keratinocytes. Thinning of the epidermis and violation of differentiation of keratinocytes lead to a violation of the barrier properties of the skin and an increase in traineepidermal water loss. Clinically described changes in the epidermis are expressed in the thinning of the skin, its dryness, superficial wrinkles; the optical properties of the stratum corneum also change, which becomes dull and acquires a yellowish tinge. Patients in menopause often register diffuse xerosis of the skin, possibly the development of a xerotic eczema. Dry skin and disruption of keratinization can be the cause of the development of palmar-plantar keratoderma (Haxsthausen syndrome). Breaking the barrier properties of the skin also leads to increased sensitivity of the skin; there are indications of increased permeability of the epidermis for various allergens and an increase in allergic dermatitis in this age group.

As for the dermo-epidermal contact, in the perimenopause period a decrease in the content of type VII collagen in anchor fibrils was noted. These changes lead to a disruption in the supply of nutrients to the epidermis and the smoothness of the basal membrane line, which also contributes to the development of atrophy of the superficial layers of the skin.

In the dermis, a decrease in the number and size of fibroblasts, as well as a decrease in their synthetic activity, primarily in relation to the production of collagen and elastin proteins, are noted. It is now known that the amount of collagen and elastic fibers, as well as the density of collagen and elastin decreases with age. It is noted that during the first 5 years after menopause, up to 30% of collagen is lost. The acceleration of degeneration of elastic fibers is recorded. There are also indications for a decrease in the solubility of collagen molecules and a change in their mechanical properties. In addition, age-related changes include the accelerated destruction of the dermis fibers. It is shown that after 40 years each person loses up to 1% of fibers per year, and during the menopause this percentage increases to 2. In addition, qualitative changes occur in the composition of glycosoaminoglycans (GAG), and the peak of these changes is recorded at 50 years , which often corresponds to the age of menopause. They also emphasize that by the age of 50, the content of chondroitin sulfate (cholesterol) decreases, especially in the papillary dermis, and also in the wrinkles.

Summarizing the complex of dermal changes in the perimenopause, we can conclude that they lead to a violation of elasticity, skin turgor and the phenomenon of first superficial and then deep wrinkles.

Currently, an important role in the formation of deep wrinkles and deformation of the face oval in the perimenopause period is attributed not only to changes in the epidermis and dermis, but also to the subcutaneous adipose tissue and facial muscles. The volume and distribution of the subcutaneous fat of the face changes. It is proved that there is a physiological atrophy of adipocytes. A decrease in the peroxisomal activity of adipocytes was noted, which leads to significant disturbances in the regulation of their population, as well as a decrease in the ability to accumulate fats.

Against the background of hypoestrogenia melanogenesis is also intensified, which often leads to the appearance of melasma (chloasma). The occurrence of erythema on the face is due to the lack of estrogen effect on the superficial vasculature. This fact is the cause of the development of rosacea - dermatosis, which is very typical for the climacteric period. A sudden sharp drop in the concentration of estradiol and a gradual decrease in the production of progesterone in a number of cases leads to an increase in androgenic effects on the skin, which result in hirsutism, seborrhea and acne (acne tarda), androgenetic alopecia. The change in the composition of sebum and the rate of its production, as well as the violation of the barrier properties of the skin predispose to the development of seborrheic dermatitis. The complex of morphological and hormonal changes can lead to the debut of psoriasis, red flat lichen and other chronic inflammatory dermatoses in menopause. In addition, with menopause, the skin becomes more prone to photoaging, as the production of sunscreen melanin becomes uneven and the skin protection system is prevented from damaging the conditioned UFOs.

Various types of aging have also been identified. When assessing signs of age-related skin changes, it is important to consider the type of aging, since the algorithms for their correction differ from each other.

1. The type of "tired face" is found in the earliest stages of aging. Characterized by a decrease in skin turgor, puffiness, facial swelling, mainly due to impaired lymph flow. With this type there are already changes in the tone of facial muscles of the face. The expression of nasolabial folds, the lowering of the corners of the eyes and lips creates the impression of fatigue and fatigue.
2. The fine-wrinkled type, or "wrinkled face," is characterized mainly by degenerative-dystrophic changes from the epidermis and dermis. Typically, a decrease in turgor, a decrease in the elasticity of the skin, its dehydration, a violation of barrier properties. The consequence of this are multiple fine wrinkles, remaining in a state of mimic rest, dry skin, the appearance of a symptom such as large-pore skin.
3. The deforming (deformation) type, or the large-grained type, or the "deformed face", is characterized by a violation of the elasticity of the skin, a decrease in the tone of the facial muscles, a violation of lymphatic drainage, and venous stasis. Changes in the tonus of the facial muscles include hypertension of the major muscles of the upper and lower third of the face and hypotonic muscle mostly middle third of the face. So, in a condition of a hypertonic there are mm. Depressor lobii inferioris, procerus, frontalis, depressor anguli oris and other muscles, in the hypotonic state - mm. Zigomaticus major and minor, orbicularis oculus, risorius, buccinator, etc. The outcome of this is a change in the configuration of the face and neck: violation of the oval line of the face, overhanging the skin of the upper and lower eyelids, the appearance of a "double" chin, the formation of deep folds and wrinkles (nasolabial fold, cervical-chin crease, wrinkles from the corners of the mouth to the chin, etc.). It is characteristic for persons with well developed subcutaneous adipose tissue. Against the backdrop of broken muscle tone and increased tissue extensibility, gravitational displacement of the subcutaneous fat in the cheek area with the formation of overhanging cheeks and the so-called "hernia" of the lower eyelid representing the accumulation of fat in the indicated zone.
4. The combined type of aging is characterized by a combination of the first three types.
5. The muscular type of aging is characterized by a decrease in the volume of subcutaneous fat. In representatives of this type, the mimic muscles of the face are initially well developed and the subcutaneous fat base is poorly expressed. Typical for residents of Central Asia and the Far East. Against the background of age-related changes marked mimic wrinkles in the corners of the mouth, on the forehead, deep nasolabial folds, smoothness of the oval line of the face are noted.

[1], [2], [3], [4], [5]