Scientific Insights into Causes and Prevention of Skin Aging

What are the causes of skin aging?

What are the causes of skin aging? Skin aging is characterized by the appearance of wrinkles, sagging skin, and thinning skin, and there are many causes for it.

It is generally divided into intrinsic and extrinsic causes. This guide describes the main causes of skin aging and explains the scientific basis of skin aging.

This guide to the aging process will be updated as new discoveries about skin aging emerge.

For a more detailed explanation of skin aging, please refer to Chapters 5 and 6 of my latest textbook, Bowman Cosmetic Dermatology (McGraw Hill 2022).

Anti-aging skin care ingredients target specific processes that cause skin aging. There are many different anti-aging ingredients, and you should choose the one that best suits your skin type.

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16 Bowman Skin Types

Biological Causes of Skin Aging

There are many cellular processes that cause skin aging. Therefore, treating skin aging can be difficult. There are many metabolic pathways that can be attacked, such as:

Cellular senescence

Autophagy

Free radicals (reactive oxygen species)

Inflammation

Short telomeres

Slower rate at which stem cells produce new cells

Decrease in growth factors

Cells lose the ability to “listen” to growth factors

Changes in gene expression

Increase in destructive enzymes such as matrix metalloproteinases (such as collagenase)

Sirtuin expression

Mitochondrial function

There are many skin care products that can protect your skin from the effects of skin aging. Choose anti-aging skin care products based on your Bowman skin type.

Science of skin aging

Senescent cells cause skin aging. Skin cells (keratinocytes and fibroblasts) go through five different cell stages:

Stem cells

Proliferating cells

Differentiating cells

Senescent cells

Apoptotic cells

Cell senescence and autophagy

Apoptotic cells are “dead skin cells” that cannot survive. They are eliminated through autophagy and other processes that recycle cell components.

Therefore, apoptotic cells are considered harmless to the skin.

However, the more senescent cells there are, the more prone your skin is to wrinkles and aging.

Senescent cells lose their ability to proliferate, and their lysosomes and mitochondria lose their function and autophagy.

(5) Senescent cells are not eliminated from the skin but remain there, contributing to skin aging.

The presence of senescent cells is associated with accelerated aging. The goal of skin regeneration is to reduce the number of senescent cells by increasing autophagy.

Senescent cells develop into the senescence-associated secretory phenotype (SASP), which is considered one of the main causes of skin aging.

SASP cells cause damage and aging by releasing the following substances:

proinflammatory cytokines, matrix metalloproteinases (MMPs), growth factors, chemokines, matrix modeling enzymes, lipids, free radicals, and extracellular vesicles (EVs).

The release of these substances by senescent cells leads to inflammation, the so-called “inflammaging” (9).

This inflammation leads to many problems, such as the loss of collagen, elastin, and extracellular matrix (ECM), which leads to fibroblast compaction, reduced DNA synthesis, and ultimately wrinkles, skin fragility, and thinning.

Autophagy is an important process by which organelles such as lysosomes and mitochondria (6) digest or “eat” themselves.

Autophagy eliminates problematic organelles and cells, such as damaged mitochondria, damaged lysosomes, and senescent cells.

Sirtuins and Skin Aging

Research shows that activation of sirtuin (SIRT-1) can extend lifespan in mammals.

Caloric restriction (10) can also activate sirtuins, which is why intermittent fasting has emerged as an anti-aging strategy. SIRT-1 slows aging and activates autophagy.

How Sirtuins Affect Skin Aging

How Free Radicals Cause Skin Aging

How Do Free Radicals Cause Skin Aging?

Free radicals (1), also known as reactive oxygen species (ROS), are formed when an oxygen molecule loses an electron and has an odd number of electrons remaining.

Oxygen molecules with paired electrons are stable; however, oxygen with unpaired electrons is “reactive” because it seeks out and steals electrons from important components, damaging them. (2)

What causes free radicals?

Free radicals are produced by:

Damaged mitochondria

Inflammation

Normal cellular metabolism

Pollution

Smoking

Ultraviolet light

Normal cellular metabolism can lead to the formation of free radicals. Damaged mitochondria can produce free radicals. This is why it is so important to protect mitochondria with antioxidants.

Free radicals attack DNA, cell proteins, and cell membranes and steal electrons, causing damage to these cell components. This causes inflammation.

Free radicals increase the concentration of:

Inflammatory factors

Transcription factors, such as activator protein (AP)-1

Nuclear factor-κB (NF-κB)

Matrix metalloproteinases (MMPs), such as collagenase, which degrade collagen in the skin

Destructive enzymes and skin aging

A group of destructive enzymes that contribute to skin aging are called matrix metalloproteinases, or MMPs.

MMPs are activated by genes, inflammation, UV radiation, and environmental pollution.

Examples of destructive enzymes that contribute to skin aging include:

Collagenase breaks down collagen.

Elastase breaks down elastin.

Hyaluronidase breaks down hyaluronic acid.

Enzymes that contribute to skin aging.

Short Telomeres and Skin Aging

Telomeres consist of a small, repeating DNA sequence at the end of chromosomes. These control the cell cycle. Telomeres shorten with each cell division.

Shortened telomeres can trigger cellular senescence, which leads to aging. (13) However, the role of telomere shortening in aging is still unclear.

Why are telomeres short? The following factors may play a role in telomere shortening:

Free radicals

Physiological stress

Inflammation

Genes that contribute to skin aging and wrinkling

Studies have provided information about which genes are important for the appearance and function of the skin. However, it is too early to develop skin care products that target genetic defects.

Glass et al. (20) showed that genetic studies on aging are only meaningful if they are conducted on human skin.

Genetic studies in animals and cell cultures have not provided any information about human genes that contribute to aging.

Aged skin shows increased expression of inflammatory genes, cytokines, and proteases.

Genes that contribute to skin aging (21) are associated with:

Cellular metabolism

DNA transcription

Signal transduction

Cell cycle regulation

Epidermal differentiation

Keratin filaments

Keratin envelope proteins

Lipid biosynthesis

Skin barrier integrity

Mitochondrial function

Cytokine production

Immune response

Aging research is still in its early stages, but findings are emerging at an accelerating pace. I will update this guide to the science of skin aging as new discoveries emerge.

However, don’t waste your money on skin care products that claim to attack genes that contribute to skin aging.

It is too early to fully understand which genes anti-aging skin care products should target.

How Inflammation Contributes to Skin Aging

When the skin becomes inflamed, many destructive processes are activated, which is called the inflammatory response.

Free radicals, destructive enzymes such as matrix metalloproteinases, and immune cells cause skin damage in inflamed skin, which can lead to skin aging. Senescent cells also form.

To prevent skin aging, it is important to identify and eliminate the cause of skin inflammation and use anti-inflammatory skin care products to counteract the inflammation.

Using the wrong skin care products can lead to skin inflammation.

Cosmeceutical anti-aging skin care ingredients should combat the cause of skin aging.

Retinoids, growth factors, exosomes, defensins, antioxidants, heparin sulfate, and ascorbic acid are all anti-aging ingredients that can fight the causes of skin aging.

The causes of skin aging are complex. To find the right anti-aging skincare, you should consider your Bowman skin type.

DQH Knowledge drop: In your 20s, your skin cell turnover decreases. (Cell turnover is a key component in keeping your skin youthful.) You know what else slows down? Your collagen production. Starting in your 20s, collagen decreases by about 1 percent per year. Should you want to prevent fine lines and wrinkles, start by eliminating behaviors that contribute to premature aging. “If it’s bad for you, it’s bad for your skin,” says dermatologist Michel Somenek. “Cigarette smoking reduces blood flow to the skin and causes premature wrinkling and a dull skin texture. Making the repeated pursed motion to inhale can also cause smoker’s lines. Alcohol and recreational drugs are toxins for the skin that damage its cellular structure and DNA,” Somenek tells us. “The faster you eliminate vices while you are young, the better chance your skin and body have to recuperate.” Also, adopting an anti-aging routine in your 20s is key. After all, the best offense is a good defense. We spoke to Somenek and experts Joshua Ross and Audrey Kunin to find out more. Keep reading for the best anti-aging products for your 20s, according to skincare professionals. Sunscreen “We all know that the sun is the number one cause of skin aging and starting the prevention in your 20s is very important,” Ross says. “The majority of your sun damage won’t start to appear until you’re in your 30s, so don’t wait until you see it surface or you’ll be behind the curve. Stay ahead of it with a good-quality zinc-based sunscreen worn daily.” Farmacy Green Defense Daily Mineral Sunscreen An invisible sunscreen with SPF 30, plus botanical extracts meant to protect skin with tons of antioxidants. Bonus: It’s clean and fine to use under makeup. Bareminerals Complexion Rescue™ Tinted Moisturizer Broad Spectrum SPF 30 Although we recommend you use your SPF and moisturizer separately, we also understand moments when you don’t have time or energy for that extra step. For those times, this bareMinerals moisturizer is a great thing to have on hand. Vitamin C Serum “A great introduction to anti-aging is to start with a vitamin C serum in your morning skincare routine,” Ross says. “It’s a powerful antioxidant that will neutralize free radicals and brighten the skin.” He adds that it’s a great way to counteract the effects of the sun’s harmful rays, which, as previously mentioned, are among the biggest causes of premature aging. Drunk Elephant C-Firma™ Vitamin C Day Serum The Drunk Elephant C-Firma is a lightweight serum that promises to give skin a glow by combining the brightening powers of vitamin C with ferulic acid, l-ascorbic acid, and vitamin E. The included sodium hyaluronate is meant to replace hydration loss, so you shouldn’t have to deal with any irritation. Sunday Riley C.E.O. Rapid Flash Brightening Serum This potent serum is jam-packed with vitamin C (15 percent, to be exact), which means it’s a potential superstar at both brightening skin and dousing it in antioxidants. Peptides Using peptides on your skin has many benefits, says Somenek. “The skin barrier is what defends the body against pollution, UV rays, bacteria, and toxins. It can be damaged by several everyday factors. Using topical peptides aids in building a stronger barrier,” he says. “Peptides comprise elastic fibers, which are a type of protein. These fibers help to make skin appear taut and firm. Peptides can also help repair damaged skin, relieve inflammation, and even out skin tone. Some peptides can kill acne-causing bacteria that is common in 20-somethings.” Kunin agrees, saying, “Peptides are an excellent entry point for supporting collagen.” She recommends looking for face and eye treatments that contain these collagen-boosting powerhouses. Charlotte Tilbury Magic Eye Rescue Cream This Charlotte Tilbury super-emollient eye cream has a base of coconut oil and shea butter (read: it’s incredibly hydrating). Botanicals plus peptides are meant to help reduce dark circles and boost collagen, respectively. This creamy moisturizer serves up potent collagen-boosting peptides and pycnogenol, and antioxidant-rich vitamin C. “Instead of sitting on top of the skin, peptides penetrate the outer layer so they go deep. The ‘signals’ they send tell the cells to produce elastin and collagen, which are needed for youthful-looking skin,” explains Somenek. At-Home Peel Pads Remember that skin cell turnover fiasco we talked about earlier? One way to help support it is by exfoliating. “Exfoliation is important to help keep skin fresh and luminous,” Kunin says. She recommends using at-home peel pads as an easy and effective way to exfoliate. “The goal in your 20s is to fight the slowing pace of cell turnover. It is wise to use products that gently exfoliate, yet still remove oil and other impurities. Products that have Alpha Hydroxy Acids (AHA) or Beta Hydroxy Acids (BHA) are a good choice.” According to Somenek, you should only exfoliate two to three times a week. “People of all ages are guilty of over-exfoliating and that can be too much of a good thing,” he says. Dermadoctor Kakadu C Intensive Vitamin C Peel Pad A few swipes of this Derma Doctor powerful peel pad promise to leave your skin glowing and smooth, thanks to the seven (yes, seven) types of chemical exfoliants, including AHA and BHA. It also contains vitamin C via Kakadu plum extract for added brightening and antioxidant protection. KEY INGREDIENTS Kakadu plum extract is sourced from the Kakadu plum, a fruit grown in northern Australia. It contains vitamin C, which restores the skin’s natural barrier, increases collagen production, and soothes irritation. Dr. Dennis Gross Skincare Alpha Beta® Universal Daily Peel Pads These are the gold standard of peel pads, with a cult following and over 900 five-star reviews on Sephora. They’re easy to use and contain a blend of anti-aging exfoliating acids. Emollient Night Cream “In your 20s, you need to start upping the hydration in your skincare routine. You may have been cautious of over-moisturizing because of acne in your teens, but as you enter your 20s, your skin transitions and becomes drier,” Ross says. “I recommend an emollient night cream added into your evening skincare regimen.” “Twenty-somethings need to make sure that they are not using creams that will clog their pores and cause excess oil production,” says Somenek. Opt for non-comedogenic products. Cerave Skin Renewing Night Cream One great choice is the CeraVe Skin Renewing Night Cream, which is a non-comedogenic night cream that leaves skin soft and glowy. It combines the moisturizing powers of ceramides and hyaluronic acid. RoC Retinol Correxion Max Hydration Creme “The best night cream ingredients contain retinol, benzoyl peroxide, and/or salicylic acid or hyaluronic acid. The goal is to moisturize, yet remove excess oil,” says Somenek. This Roc Retinol Correxion cream fits the bill as it contains both hyaluronic acid and retinol so it promises to moisturize while also being non-comedogenic.

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