Understanding photoageing: mechanisms, visible signs and shifting beauty routines

Chronological ageing is a natural process that occurs over time and manifests differently in individuals based on genetics and lifestyle factors. Its signs include thinning of the skin, dryness, fine lines, wrinkles, and a gradual loss of elasticity. Additionally, breakdown of macromolecules of the dermis, including collagen, hyaluronic acid, elastin leads to a reduction in skin volume and loss of its mechanical properties.

Unlike chronological ageing, photoageing is not a natural process but the result of excessive light or sun exposure. While sunlight is essential for overall health - playing a key role in processes like vitamin D synthesis - prolonged or repeated UV exposure accelerate chronological aging and skin damage.

Photoageing is a recognized cause of premature ageing, it accelerates the natural ageing processes of the skin, leading to significant structural and functional changes. These include variable epidermal thickness, dermal elastosis, decreased or fragmented collagen, increased matrix-degrading metalloproteinases, inflammatory infiltrates and pigmentation disorders. [1]. Externally, these alterations manifest as wrinkles, fine lines, age spots, and a loss of skin elasticity and firmness.

Among the more pronounced signs of photoageing is solar elastosis, also known as actinic elastosis.

This condition occurs when prolonged sun exposure leads to the accumulation of abnormal elastic tissue in the dermis, resulting in thickened, yellowish, and deeply wrinkled skin. Solar elastosis significantly compromises the skin's structural integrity and elasticity, making it a hallmark of advanced photoageing. [2]

Beyond visible changes, photoageing profoundly impacts the epidermis, the skin's outermost layer. One critical impact of photoageing is the disruption of the epidermis's ability to regenerate itself effectively. The vital role in maintaining the skin's barrier function of the outermost skin layer is weakened.

Collagen and elastin production and structural organization are also damaged by light exposure, resulting in loss of skin volume and elasticity leading to sagging and the formation of wrinkles. [3]

Photoageing also affects skin pigmentation.

Melanin, the pigment responsible for skin color, is stimulated by UV exposure during tanning and provides a natural form of photoprotection. In young skin, melanocytes are evenly distributed, but their number or activity decreases by 10–20% per decade with age, leading to reduced pigmentation and tanning in sun-protected areas. In contrast, areas chronically exposed to the sun experience disruptions in the synthesis and distribution of skin pigmentation, leading to the formation of age spots, a hallmark of photoaged skin.

Preventing photoageing is essential for maintaining healthy, youthful skin. While completely avoiding sunlight is neither practical nor desirable, as we have seen in the first chapter of this series, adopting a proactive skincare and lifestyle routine can greatly minimize the negative effects of UV exposure. Key preventive measures include a conscious consumption of sunscreens, protective clothing, and avoiding peak sun exposure. While sunscreens are essential for protecting the skin from UV damage certain active ingredients are specifically formulated for skincare products to treat and prevent photoageing. For instance, retinol & its derivates and hydroxy acids are highly effective skincare ingredients to repair damage and improve skin texture (while being not suitable for suncare formulations as they can weaken the skin and reduce its ability to defend against the harmful

effects of the sun). On the other hand, antioxidants and brightening agents can often be used in both suncare and skincare, offering benefits such as regulation of melanin production & distribution and enhanced skin tone. [4] [5]

A comprehensive beauty routine including sun protection and effective skincare treatments helps maintain resilient, healthy skin, aligning with the growing demand for solutions that preserve its radiance.