The manner in which your skin ages is a highly complex process controlled by both internal systems (chronological age, genes, etc.) and external influences (sun/UV exposure, pollution, gravity, diet, smoking, illness, etc.). These factors contribute to the signs of aging that appear on our skin. However, how these signs appear on everyone’s skin is not the same, nor is when they appear completely consistent with chronological age.

Visible Variations in Aging Skin

Visible signs of aging skin have traditionally been divided into four primary characteristics:

1)  Wrinkles/texture - Appearing around the lip area, crow’s feet and under eye, cheek and jawline folds, and chin texture

2)  Sagging - Evident in the lower half of the face, upper eyelids and under eye,

3)  Changes in pigmentation - Manifested as dark spots, unevenness between, below and around the eye, and overall darkening

4)  Changes in microvasculature- Diffusion of redness and visible microvessels at the cheekbone.¹

The appearance and severity of these features have been documented² for Caucasian, Asian, and African-American skin in some detail.

While wrinkles are the most dramatic feature of skin texture³, a recent study found that evaluating wrinkles around the eye area only revealed small differences. However skin roughness around the corner and below the eye is a better measure of differences in aging skin between ethnicities. In studies of Japanese, Chinese, and German volunteers⁴, the German population exhibited the most extreme scores.

Going Beneath the Surface

The outer appearance of the skin is also affected by its structure below the surface, much like an unsound foundation or frame will reflect in the outward appearance of a house. Researchers have used in vivo imaging techniques to analyze sun-protected and sun-exposed skin of African-Americans, Mexicans, Chinese and Caucasians. Using optical coherence tomography, it was identified that the thickness of the dermal-epidermal junction decreased with age. Increasing dermal structural changes with age were most pronounced in Caucasians, with some effect noted in Chinese and Mexican groups and the least pronounced in African Americans. ⁵  The thinning of the dermal-epidermal junction and the structural changes within the dermis will commonly manifest in later years as lines and wrinkles.

Elastin also plays an important role in skin appearance, keeping skin firm and contributing to a youthful appearance. When samples from Caucasian and African-American skin were compared, differences were also observed in the elastin fiber network and the signaling that controls it ⁶. Elastin expression in African-American skin did not differ between photoexposed and photoprotected sites. When compared to Caucasian skin, cell growth and differentiation signaling was enhanced, translating to more UV-induced loss of elastin in Caucasian skin and differences in perceived age among the two ethnic groups.

An imaging study sought to analyze the individual contributions of melanin and hemoglobin to skin color variations in Asian and Caucasian skin, as well as examine any changes with increasing age⁷. They found age-related changes in the melanin component of both Asian and Caucasian skin, but the variation of hemoglobin was much more pronounced in Caucasian skin. In another study, skin color and color variety changes associated with age in four ethnic groups (African-American, Chinese, Mexican, and Caucasian) was evaluated ⁸ Darkening of skin color was observed in all ethnic groups in correlation to increasing age, with African-American skin showing the smallest increase. There was some increase in the yellow component of skin in Chinese volunteers as age increased. Skin color variation was most pronounced in African-American skin as age increased.

Skin Hydration and Sun Exposure

The effect of age and ethnicity on skin surface components (sebum, sweat, epidermal lipids, and Natural Moisturizing Factor) appeared to be negligible or non-detectable in a study of 315 volunteers (African, Caucasian, or Asian) aged 14-30.⁹

The results are different for skin hydration, however. In comparing both the sun exposed and sun protected skin of African-Americans, Chinese, Mexicans and Caucasians it was observed that skin dryness is more pronounced in sun exposed, (especially for Caucasians and Chinese) than on sun protected sites.¹⁰ No differences in dryness were observed in darker skin when comparing sun exposed and sun protected skin. Further, skin dryness did not change in the 18-50 age group, but was more pronounced in African-American and Caucasian skin at age 51+, with a greater percentage increase in Caucasian skin.  While a study comparing age related transepidermal water loss (TEWL) between African American and Caucasian skin showed minimal differences, significant differences were noted in the ease and number of cells exfoliated with age from sun exposed skin in both ethnic groups. The change noted was greater for Caucasians.

This is a glimpse into what researchers have begun to uncover about the changes occurring with our skin as we age. The fact that these changes are not always consistent across ethnic groups re-emphasizes the need for a deeper understanding of skin biology from diverse populations. This understanding may translate into more personalized and more effective treatments for aging skin. To preserve your skin’s youthful appearance, use your sunscreen and ensure that your skin receives adequate moisture. Implementing these simple steps into your skincare routine will help to increase your skin’s moisture barrier as well as increase protection against environmental damage. ■

Sources:

1.       Flament, F. et al. (2013) Effect of the sun on visible clinical signs of aging in Caucasian skin. Clin Cosm Invest Dermatol 6:221-232.

2.       Bazin, R. et al. Skin Aging Atlas, Paris. Editions Med’Com, v1 (2007) v2 (2010) v3 (2012).

3.       Nkengne & Bertin C. (2013) Aging and facial changes--documenting clinical signs, part 1: clinical changes of the aging face. Skinmed 5:281-6.

4.       Fujimura, T. et al. (2009) Roughness analysis of the skin as a secondary evaluation criterion in addition to visual scoring is sufficient to evaluate ethnic differences in wrinkles.  Int J Cosmet Sci. 31:361-367.

5.       Querleux, B. et al. (2009) Skin from various ethnic origins and aging: an in vivo cross-sectional multimodality imaging study. Skin Res Tech 15: 306-313.

6.       Fantasia, J. et al. (2013) Differential levels of elastin fibers and TGF-β signaling in the skin of Caucasians and African Americans. J Derm Sci 70: 159-165.

7.       Kikuchi, K. et al. (2014) Image analysis of skin color heterogeneity focusing on skin chromophores and the age-related changes in facial skin. Skin Res Tech Epub 2014 Aug 11. doi: 10.1111/srt.12174.

8.       de Rigal, J. et al. (2010) The effect of age on skin color and color heterogeneity in four ethnic groups. Skin Res Tech 16: 168-178.

9.       Shetage, S.S. et al. (2014) Effect of ethnicity. gender and age on the amount and composition of residual skin surface components derived from sebum, sweat and epidermal lipids. Skin Res Tech 20: 97-107.

10.    Diridollou, S. et al. (2007) Comparative study of the hydration of the stratum corneum between four ethnic groups: influence of age. Int J Dermatol Soc 46(Suppl 1): 11-14.

11.    Chu, M. & Kollias, N. (2011) Documentation of normal stratum corneum scaling in an average population: features of differences among age, ethnicity and body site. Brit J Dermatol 164: 497-507.