Skin aging: causes, prevention, and treatments

In 2012, the New England Journal of Medicine published a photograph of a 69-year-old American truck driver. He had driven for twenty-eight years, with the window on his left. The left side of his face was deeply marked, thickened, and furrowed with deep wrinkles. The right looked like that of a much younger man.

Same person, same genes, same age, same habits. The only variable was the sunlight coming through a car window. It is the clearest demonstration there is of something that changes everything: skin aging is not one single thing. It consists of two different processes happening together, and only one of them is something we can influence.

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The two rates: intrinsic and extrinsic

Intrinsic aging, or chronological aging, is written into our biology. Fibroblasts slow down, cell turnover takes longer, and the production of lipids and hyaluronic acid declines. It progresses slowly and fairly uniformly throughout the body. It cannot be stopped, and there is no point in fighting it.

Extrinsic aging is induced by what the skin is exposed to: ultraviolet rays above all, followed by pollution, smoking, stress, sleep deprivation, and diet. Research groups it under the name skin exposome, the set of cumulative environmental factors we are exposed to over the course of our lives.

The difference is visible to the naked eye, and you don’t need to be a truck driver to notice it: compare the skin on the inside of your arm with that on the back of your hand. The same chronological age, but completely different exposure.

And here’s the good news. The factors that have the greatest impact on facial appearance — spots, deep wrinkles, loss of firmness, uneven complexion — largely belong to the second group. In other words, they’re the modifiable ones.

The five mechanisms that age the skin

Behind the appearance are distinct biological processes. Distinguishing them matters, because each treatment acts on one or two of them, and none acts on all of them.

1. Oxidative stress

This is the driving force behind almost everything else. UV rays, pollution, and smoke generate free radicals, unstable molecules that damage lipids, proteins, and cellular DNA.

2. Collagen breakdown

Free radicals cause cells to produce metalloproteinases, the enzymes that break down collagen. This is how the sun truly causes aging: it does not burn the fibers; it causes the skin to produce the enzymes that break them down.

There is a second change involving collagen that is less noticeable. It is not just the amount that decreases: the type changes. Type III collagen, the most elastic kind, gradually decreases, while type I becomes stiffer as free radicals promote the formation of cross-links. The result is a dermis that still has structure but is stiffer and slower to repair itself.

3. Glycation

Excess sugar binds to structural proteins, forming advanced glycation end products. The result is not less collagen, but collagen that is stiffer and loses its ability to deform and spring back. It is a slow process largely linked to diet, explained in the article on skin glycation.

4. Loss of elastin

Elastin is the protein responsible for elastic recoil, and unlike collagen, the adult body produces very little of it. In skin that has been heavily exposed to the sun, degraded and disorganized elastic fibers accumulate: this is why skin with extensive sun exposure looks thickened and yellowish, not just wrinkled.

5. Low-grade chronic inflammation

A constant, subclinical level of inflammation accelerates all the processes described above. It is driven by pollution, chronic stress through cortisol, and insufficient sleep. This is why a difficult period shows on your face even when your skincare routine remains the same.

The exposome: what really accelerates the process

Ultraviolet rays. The number-one factor, without equal. UVA rays penetrate deeply, pass through glass, and are present year-round, even when the sky is overcast. Daily sun protection is the single most thoroughly documented preventive measure in cosmetics.

Air pollution. Fine particulate matter settles on the surface and causes continuous oxidation.

Smoking. It increases collagenase production and reduces tissue oxygenation. It has a recognizable pattern, with pronounced crow's feet and a grayish complexion.

Blue light. Much talked about and less decisive than claimed: the evidence mainly concerns pigmentation in darker skin types. We discuss it in detail in the article on blue light and skin.

Sleep and stress. Peak skin repair occurs during deep sleep, which chronic stress shortens first.

If I had to rank them by effectiveness: daily sun protection, not smoking, getting enough sleep. They come before any serum, and no active ingredient can make up for their absence.

What a cosmetic product can and cannot do

It is worth being precise, because promises in this area are often disproportionate.

It can reduce oxidative stress with antioxidants, slow collagen degradation, support synthesis through peptides, improve hydration and surface firmness, even out skin tone, and prevent future damage with photoprotection.

It cannot recreate lost volume, reorganize already degraded elastic fibers, erase deep static wrinkles, or restore the structure of the dermis. When one of these is the goal, the appropriate field is aesthetic medicine, and it is right to know this before buying.

The dividing line, in practice, is this: lines that appear only when the face moves still have real room for cosmetic improvement; those visible when the face is still have very little, because they correspond to a structural change in the dermis.

Where to start

Ranked by effectiveness, not price.

1. Broad-spectrum sun protection, every morning, all year round. On its own, it is worth more than everything else combined.
2. Antioxidants in the morning, to intercept free radicals before they trigger metalloproteinases. With a second benefit: they also slow the formation of cross-links that stiffen the fibers already present.
3. Actives that support synthesis at night: peptides or retinoids, introduced one at a time and gradually.
4. Keep the barrier in good condition. A compromised barrier remains inflamed, and inflammation accelerates everything else.

The article dedicated to the five actives for premature aging explains which actives have the strongest evidence. The full range is in the LeLang selection of anti-aging treatments.

Understanding where you are—whether there is still room for prevention or whether you need to work on the structure—is not always obvious in the mirror, and getting it wrong means waiting months to realize it. At LeLang partner pharmacies, you can find a pharmacist who can assess it.

Frequently asked questions

At what age does skin aging begin?

Earlier than you might think: fibroblasts already slow down between the ages of twenty-five and thirty, long before anything becomes visible. But the extrinsic component begins with the first sun exposure, meaning during childhood. That is why sun protection for children is an investment in the face they will have at fifty.

Do you need an anti-aging cream at thirty?

You need sun protection, as well as antioxidants. Actives that work on fibroblasts make more sense from the age of thirty-five onward. At thirty, a cream packed with actives will not do any harm, but it will not add much either: the real leverage lies elsewhere.

Why do some people age better?

Genetics, phototype, accumulated exposure, and lifestyle, in different proportions. The genetic component exists and is real, but it is the part that cannot be changed; the factors you can influence still account for a very large share of the difference.

Does sunlight through glass count?

Yes, and that is exactly the story of the truck driver. Ordinary glass blocks UVB but lets a large proportion of UVA through, which are the main culprits behind photoaging. People who drive a lot or work next to a window often have one side of their face more weathered than the other.

Can existing damage be repaired?

Partly. Complexion, dark spots, hydration, and surface firmness improve noticeably. The deeper structure does not: what is already there can be preserved. Anyone who promises to “reverse” aging is selling an expectation, not a result.

Is it better to prevent or treat?

Prevention, without question, because preventing damage costs far less than repairing it—in time, money, and achievable results. But the two are not mutually exclusive: at any age, prevention continues to pay off.

Sources for this article

01 Gordon J.R., Brieva J.C., Unilateral dermatoheliosis, New England Journal of Medicine, 2012; 366(16): e25.
02 Fisher G.J., Kang S., Varani J., Bata-Csorgo Z., Wan Y., Datta S., Voorhees J.J., Mechanisms of photoaging and chronological skin aging, Archives of Dermatology, 2002; 138(11): 1462-1470.
03 Krutmann J., Bouloc A., Sore G., Bernard B.A., Passeron T., The skin aging exposome, Journal of Dermatological Science, 2017; 85(3): 152-161.
04 Hughes M.C., Williams G.M., Baker P., Green A.C., Sunscreen and prevention of skin aging: a randomized trial, Annals of Internal Medicine, 2013; 158(11): 781-790.
05 Gkogkolou P., Böhm M., Advanced glycation end products: key players in skin aging?, Dermato-Endocrinology, 2012; 4(3): 259-270.

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