In brief

Chronological aging affects the scalp and hair in both genders. An investigation of the histo-pathological structures of the scalp of 300 women and 350 men has showed that solar elastosis appeared as a hallmark of scalp aging. Alopecia is involved in the so-called stress-induced premature senescence of the interfollicular scalp. There is a gender difference in the interfollicular scalp condition of young adults without alopecia.

Introduction

The cutaneous histo-pathological structure of the scalp is different from any other part of the body and is, nonetheless, subjected to changes during life span in both genders. Changes results from the combination of a series of intrinsic and extrinsic factors such as genetic, chronological, actinic, behavioral, endocrine, catabolic, and gravitational effects. However, except for senescent alopecia, little information is available about chronological aging of the scalp and hair, in relation with gender.

In a study performed on a population of 650 volunteers (300 women and 350 men) for over 7 years, biopsies from the parietal area were obtained and processed for immunohistochemistry. Possible variations in the structures of the interfollicular part of the reticular dermis and epidermis according to gender, age, and alopecia status were investigated.

Influence of gender

In men, there was a significant larger amount of solar elastosis (lysozyme+), an increase in dermal cellularity and dermal dendrocytes (Figure 1). The epidermis was also thicker.

Figure 1. Typical aspects of immunohistological labelin of lysozyme in severe solar elastosis.

In women, the blood and lymphatic evssels as well as the density of mast cells were more developed.

Influence of age

There was a reduction in skin vascularity with scalp aging affecting predominantly blood vessels rather than lymphatics.

In older men, the most prominent age-related changes consisted in an increased amount of lysozyme-coating elastotic fibers and a reduction in the size of vascular lumens.

In older women, there was an increased in lysozyme deposits in the dermis and reduction in both the volume of stromal cells and the number of mast cells

Influence of alopecia

The effect of alopecia, if any, was only assessed in young adults for avoiding the confounding influence of aging.

In men, alopecia was associated with an increase of stromal cells and lymphatic vessels. The epidermis was thinner. Young alopecic men had fewer dermal cells but larger stromal cells and enlarged lymphatic vessels.

In women, alopecia was associated with an increase in lysozyme deposits on elastotic fibers. Young alopecic women showed a prominent increase in lysozyme deposits on elastic fibers whereas blood vasculature was reduced. In addition, their epidermal was thinner.

Conclusion

The scalp is tightly bound to the underlying structures. Solar elastosis appeared as a hallmark of scalp aging. As well, alopecia appears as one factor involved in the so-called stress-induced premature senescence of the interfollicular scalp. There is a gender difference in the interfollicular scalp condition of young adults without alopecia.

Reference

Piérard-Franchimont C. et al. Immunohistochemical Patterns in the Interfollicular Caucasian Scalps: Influences of Age, Gender, and Alopecia. Biomed Res Int. 2013;2013:769489