Can we prevent skin aging?

Indian Journal of Dermatology, Venereology and Leprology, Sep/Oct 2009 by Singh, Gurcharan

The desire to look young and in turn vital has been a lure to man since ancient times, though aging as a rule remains a fact of life. The current advances in health sciences have lead to a boost in average life expectancy; hence, aging skin has set to become an issue to the current dermatologists. Increasing awareness regarding skin research has lead dermatologists and common man alike to seek out for answers concerning the complexities of the aging process.

Ayurveda, one of the oldest sciences of India, describes aging as ' Jar, ' defined as that which has become old by the act of wearing out 'jryati iti jar'. It is synonymed as ' vrdhakya' meaning increasing age. [1] Biologists define aging as a genetic physiological process associated with morphological and functional changes in cellular and extracellular components aggravated by injury throughout life and resulting in a progressive imbalance of the control regulatory systems of the organism, including hormonal, autocrine, neuroendocrine, and immune homeostatic mechanisms. [2] In short, aging is a process in which both intrinsic and extrinsic determinants lead progressively to a loss of structural integrity and physiological function. [3] The theories of aging are defined as following:

Cross-linking theory of aging

This theory is based on the observation that our proteins, DNA, and structural molecules develop inappropriate cross links to one another and look like older tissue as deduced by researchers on experiments with brain tissue.

Wear and tear theory of aging

Years of damage to cells, tissues, and organs wear them out, killing them, and then the body. Telomerase the cap of DNA shortens with each cell division and reaches critical short length beyond which cell cannot divide and becomes senescent.

Free radical theory of aging

Free radicals cause DNA damage, cross linking of proteins, and formation of age-pigments, hence irreversible damage.

Somatic mutation theory of aging

The somatic mutations that are not corrected and accumulate will cause cell malfunction and death.

The pacemaker theory of aging

It suggests that the two biological clocks, neuroendocrine system and the immune system are set at birth to run for a specified period.

Genetic theory of aging

According to this theory, life span determining genes are inherited and are called longevity assurance genes, and they determine the process of aging

Biological Markers of Aging

These are measurable indicators of aging and they include in vitro proliferative capacity of fibroblast, glycation of collagen, and DNA unwinding rate. [4]

Chronologically aged skin is thin, relatively flattened, dry and unblemished with some loss of elasticity and age-related loss of architectural regularity. General atrophy of the extracellular matrix is reflected by a decrease in the number of fibroblasts. Reduced levels of collagen and elastin, with impaired organization are primarily because of decreased protein synthesis affecting types I and III collagen in the dermis, with an increased breakdown of extracellular matrix proteins.[5] Aging happens due to a variety of reasons.

These are as following:

Constant effect of gravity on soft tissue results in their sagging over the facial skeleton.Sun damage to skin.Hormonal changes in women around menopause.Decreased skin blood flow associated with aging.Weight gain due to slow down of metabolism and fat deposition in regions of body called 'depots'. Fascial and ligament laxity.Shrinkage of glandular tissue (Salivary glands).Skeletal resorption. [6]

There are two types of aging, intrinsic aging and extrinsic aging. Intrinsic aging is the slow irreversible degeneration of tissue that affects almost all body organs. [7] Intrinsic or natural aging is cellularly determined as a function of heredity, is inevitable, and results in cutaneous alterations. [8] The rate of aging is significantly different among different populations, as well as, among different anatomical sites even within a single individual. The intrinsic rate of skin aging in any individual can also be dramatically influenced by personal and environmental factors, particularly the amount of exposure to ultraviolet light. [5]

The common signs of intrinsic skin aging are:

Fine wrinklesThin and transparent skinLoss of underlying fat leading to hollowed cheeks and eye sockets with noticeable loss of firmness on the hands and neckBones shrink away from the skin as a result of bone loss, which causes sagging skinDry skin with pruritusInability to sweat sufficiently to cool the skinGreying hair eventually turning white [8]

Skin that age intrinsically is smooth and unblemished, and characterized by normal geometric patterns, with some exaggerated expression lines. Histologically, such skin manifests epidermal and dermal atrophy, flattening of the epidermal rete ridges, as well as reduced numbers of fibroblasts and mast cells. In addition, increases are seen in the number of collagen fibrils as well as the ratio of collagen III to collagen I. [9]