Normal and Aging Hair Biology and Structure ‘Aging and Hair'

Abstract

Much like an individual's hairstyle, hair fibers along the scalp see a number of changes over the course of one's lifetime. As the decades pass, the shine and volume synonymous with youthful hair may give way to thin, dull, and brittle hair commonly associated with aging. These changes are a result of a compilation of genetic and environmental elements influencing the cells of the hair follicle, specifically the hair follicle stem cells and melanocytes. Telomere shortening, decrease in cell numbers, and particular transcription factors have all been implicated in this process. In turn, these molecular alterations lead to structural modifications of the hair fiber, decrease in melanin production, and lengthening of the telogen phase of the hair cycle. Despite this inevitable progression with aging, there exists an array of treatments such as light therapy, minoxidil, and finasteride which have been designed to mitigate the effects of aging, particularly balding and thinning hair. Although each works through a different mechanism, all aim to maintain or potentially restore the youthful quality of hair.

Histopathology of aging of the hair follicle

“…There are two facts that relate the hair cycle with the process of graying of the hairs. First, telogen phase ─ which is a period of no transfer of melanin ─ lengthens with age . Second, the repigmentation and reconstruction of the melanocytic unit of the hair follicle periodically vanishes with each cycle and eventually is not possible anymore after 7 to 15 cycles, which is the equivalent to 40 to 45 years of age .…”

“…Hair graying is a complex process considered to be mainly genetic, with several other influencing factors. Similar to skin aging (where exogenous and endogenous forms of aging are distinguished), hair graying is also influenced by genetic as well as environmental factors that act on the hair follicle stem cells, as well as on the hair melanocytes . Pollution, UV radiation, psycho‐emotional factors, nutritional status, metabolism, cigarette smoking, ethnical, and sex differences, and inflammatory stress are some of the variables conditioning the premature graying of the hair .…”

“…With aging, hair usually turns more dry, thin, dull, and brittle . This is accompanied by weathering of the shaft, with decreases in the melanin production and hair production, which are clinically evidenced as graying of the hair.…”

Current application of phytocompound-based nanocosmeceuticals for beauty and skin therapy

“…inflammation and growth disorders, which vary with the individual. [98][99][100][101] This affects the social status of individuals due to changes in physical appearance of the increased hair loss by vellus follicles transformations. 102 Several plant-derived phytobioactive compounds are extensively used in the hair care products.…”

Kidneys in Oriental and Occidental Medicine

“…Aging is considered as kidney deficiency. In other words, aging is characterized by the immune, neural and endocrine dysfunctions mentioned above, such as diabetes mellitus, anorexia, hypobulia [22], cognitive dysfunction [23,24,25], hypertension [26], osteoporosis [25], alopecia [27] and chill [28], in addition to arteriosclerosis [29] resulting from slight inflammation [30]. In summary, the concept of the kidney in Oriental medicine is broader than that in Occidental medicine.…”