Aging is a complex process influenced by both extrinsic and intrinsic factors. Premature signs of aging due to cumulative UV exposure represent a major concern of the cosmetic patient. Skin of color is less susceptible to photodamage and thus signs of aging are less pronounced and occur later than in Caucasians. Understanding structural and functional differences among different racial/ethnic groups is important to achieve favorable treatment outcomes when addressing aging concerns.

INTRODUCTION

Skin aging is a complex phenomenon in uenced by extrinsic and intrinsic factors. Variations in age of onset, severity, and specific concerns are observed across the spectrum of racial/ethnic populations. According to the US Census Bureau Projections, by 2044 more than half of the United States (US) is projected to belong to a non-white racial and ethnic group.1 As the minority population continues to grow, minorities represent an expanding cohort seeking cosmetic procedures. As such, understanding structural and functional differences of the skin and aging process in different skin types is of increasing importance.

Structural and Functional Differences

Darkly pigmented skin is characterized by larger, more numerous melanosomes that contain more melanin and are more singly dispersed throughout the epidermis compared to lightly pigmented skin. The increased melanin content and widely dispersed melanosomes in darker skin provide photoprotection.2 In a 1979 study by Kaidbey et al using cadaveric skin, the mean protective factor from Ultraviolet (UV) B radiation in black skin was found to be 13.4 compared to 3.4 for white skin; and the mean rate of UVB transmission into the dermis was 5.7% in black skin compared to 29.4% in white skin.3 While increased melanin is advantageous in delaying the onset and/or reducing the severity of photoaging in darker skin, labile melanocyte responses contribute to a greater risk of pigment alteration - a feature of both photoaging and a common sequela of inflammation and injury.4 There are also structural differences in the dermis and epidermis that can potentially influence variations in aging. Notwithstanding inherent limitations of limited studies with small sample sizes, the stratum corneum in black skin (compared to white skin) has been reported to have more layers that are arranged more compactly.2,5 Additionally, broblasts have been reported to be larger, more numerous, and more frequently binucleated or multinucleated in black skin vs white skin, generating compact collagen bundles that are arranged more parallel to the epidermis.2,5 The heightened broblast activity is thought to contribute to the lower incidence of facial rhytides, but increased risk of keloids in black skin and other darker skin types.

Aging

In general, signs of aging occur at a later age and are less pronounced in ethnic skin. Facial wrinkles and ne lines appear later in African Americans than in Caucasians and may not appear until late in the fth or sixth decade.4 In a multi-national, cross-sectional, web-based survey study assessing ten facial features of aging across different racial/ethnic groups and Fitzpatrick types, white women self-reported more signs of moderate and severe facial aging than Asian and Hispanic women beginning in the fourth decade.6 In more than 30% of study participants aged 40-49, white individuals reported to have forehead lines, glabellar lines, crow’s feet, nasolabial folds, and puffiness under the eyes, in contrast to the presence of nasolabial folds and puffiness reported by Asian women and nasolabial folds in Hispanic women.6 In this study, black women did not describe signs of facial aging until the fifth decade and these were limited to nasolabial folds and forehead lines.6 When comparing the severity of facial features against photo-numeric rating scales, the mean severity of crow’s feet lines were most severe in Fitzpatrick skin type I and least severe in Fitzpatrick skin types IV and V.6 Hyperpigmentation and uneven skin tone are of greater concern in individuals with skin of color compared to patients with lighter skin types, among whom ne lines and wrinkles are more frequent concerns. Patients with skin of color are additionally more prone to develop and become preoccupied with the ac-