Fine lines, expression lines and wrinkles: they are not the same thing

"I have wrinkles" is a sentence that covers a lot of ground. It can mean some fine lines under the eyes that appear at the end of the day, the creases on the forehead when you raise your eyebrows, or a groove that is already there with the face at rest. In the mirror they look like variants of the same problem. In the skin, they are three different phenomena, with different causes and different responses to care.

Knowing which is which saves money and frustration. A moisturiser can make dehydration lines disappear within hours, but it does not change an expression line. A treatment that relaxes the muscle softens the forehead line, but does not restore volume to a groove. And no cream erases a deep wrinkle.

What changes in the skin over time

To understand the lines, it helps to understand the structure. The skin has three main layers, and each contributes in its own way:

• Epidermis, the surface layer. Its capacity to retain water depends on the skin barrier. When the barrier fails, the surface becomes dry and is marked with small lines.
• Dermis, the skin's "mattress". It is made mainly of collagen (which gives firmness), elastin (which gives elasticity) and hyaluronic acid (which retains water). With age, less collagen is produced and the existing collagen degrades; the elastic fibres fragment; the dermis becomes thinner and less able to "bounce back" after being folded.
• Hypodermis and deep structures: fat, muscle, ligaments and bone. With age, the fat compartments of the face change in volume and position, and the bone remodels. This creates grooves and folds.

There are two ageing "engines" acting at the same time:

• Intrinsic ageing, chronological and genetic, slow and inevitable.
• Extrinsic ageing, caused mainly by solar radiation (photoageing), but also by tobacco and pollution. In a study of Caucasian women, sun exposure was associated with around 80% of the visible signs of facial ageing, including wrinkles, dark spots and loss of firmness (Flament et al., 2013).

Ultraviolet radiation activates enzymes that break down collagen (metalloproteinases) and reduces its production (Fisher et al., 2002). That is why two people of the same age can have very different skin, depending on the sun they have had.

Fine dehydration lines: the surface asking for water

They are the most superficial lines and the easiest to resolve. They do not result from changes in the dermis, but from a stratum corneum with little water, which loses flexibility and "wrinkles" at the surface, like dry paper.

How to recognise them:

• Very fine, criss-crossing lines, in a net or diamond pattern, more visible in side lighting.
• They appear mainly on the cheekbones, under the eyes and on the forehead.
• They vary through the day: they get worse in the late afternoon, in air-conditioned or heated environments, after a flight or a bad night's sleep.
• The skin may feel tight, dull or have a "crepey" texture.
• They appear at any age, including at 20.

Simple test: apply a moisturiser with humectants (glycerin, hyaluronic acid) and wait 30 to 60 minutes. If the lines soften a lot or disappear, they were mainly from dehydration.

Why they matter: they are not true wrinkles, but chronically dehydrated skin with a weakened barrier tends to age worse and to become more irritated by anti-ageing actives. Correcting hydration is the foundation on which everything else works.

If you want to find out whether your skin is dry (lacking lipids) or dehydrated (lacking water), see Dry skin or dehydrated skin: what is the difference and why it matters.

Expression lines: the face in motion

Expression lines, or dynamic wrinkles, are creases that appear when the facial muscles contract and disappear when the face relaxes. The muscles of the face have a particularity: many are inserted directly into the skin. Each time they contract, they pull and fold the skin above, always in the same place and in the same direction.

The most common:

How to recognise them: make the expression in front of the mirror and then relax. If the line appears with movement and disappears completely at rest, it is dynamic.

Why they appear first in certain areas: the forehead and the eye area have very active muscles and, around the eyes, particularly thin skin with fewer sebaceous glands. That is why crow's feet and forehead lines are usually the first signs, often between the ages of 25 and 35. Individual expression also counts: people who frown a lot, smile a lot or squint in the sun mark these areas more. See Crow's feet and forehead lines: why they appear first.

Expression lines are not a problem in themselves. They are the face at work. But, over years, repeated folding in skin that is gradually losing collagen and elasticity ends up leaving a permanent crease.

Static wrinkles: when the line no longer goes away

A static wrinkle is visible with the face at rest, without any expression. It is usually the progression of an expression line: over time, the dermis loses the ability to recover its shape after being folded, and the crease becomes etched in.

Several factors contribute to this transition:

• Loss of collagen and fragmentation of elastic fibres, mainly from the action of the sun.
• Thinning of the dermis and epidermis.
• Repeated movement over years.
• Tobacco, which reduces collagen synthesis and blood supply to the skin, and whose gesture marks the area around the mouth.
• Genetics and phototype: fair, thin skin tends to wrinkle earlier.

How to recognise them: with the face completely relaxed, the line is there. Gently stretching the skin with two fingers may smooth it, but it does not disappear completely if it is deep.

Grooves and folds: they are not wrinkles

The nasolabial fold (from the nose to the corner of the mouth), the marionette lines (from the corner of the mouth to the chin) and the tear trough are often called wrinkles, but they have a different origin. They are folds created by the difference in volume and support between neighbouring areas: loss and descent of fat, weakening of ligaments, bone remodelling. Everyone has a nasolabial fold, even at 20; with age, it becomes more marked.

This has a practical consequence: creams and surface treatments have little effect on grooves, because the problem is not in the skin, but beneath it.

Sleep lines: the wrinkles from the pillow

There is also a less well-known category. People who sleep on their side or face-down compress and distort the skin of the face for hours, every night. A review published in 2016 described these "sleep wrinkles" as distinct from expression wrinkles: they run in different directions (often vertical, on the temples, forehead and cheeks), tend to be more marked on the side the person sleeps on and do not respond to treatments that relax the muscles (Anson et al., 2016). They are visible on waking and gradually fade; over the years, they can become permanent.

Side by side: how to tell them apart at home

A three-step test, in the mirror and in good light:

1. With the face relaxed, look at the area. If you see no line at all, but it appears when you make the expression, it is dynamic.
2. If the line is visible at rest, gently stretch the skin with two fingers. If it is a fine network that disappears easily, think of dehydration; repeat after moisturising. If it is a defined crease that persists, it is static.
3. If it is a broad fold, such as from the nose to the mouth, gently push the cheek up and back. If the fold almost disappears, the problem is volume and support, not the skin.

How professionals classify

In clinical practice, the Glogau classification is frequently used, describing photoageing in four types (Glogau, 1996):

• Type I, no wrinkles: early photoageing, minimal pigment changes, no wrinkles. Usual between the ages of 20 and 30.
• Type II, wrinkles in motion: expression lines that appear when smiling or frowning, first dark spots. Usual between the ages of 30 and 40.
• Type III, wrinkles at rest: wrinkles visible without expression, evident dark spots and texture changes. Usual from the age of 50.
• Type IV, wrinkles only: generalised wrinkles, yellowish and greyish skin, sometimes pre-malignant lesions. Usual from the age of 60 to 70.

The ages are indicative: sun exposure and tobacco bring these types forward considerably.

What works for each type

Dehydration lines

• Moisturiser with humectants (glycerin, hyaluronic acid, urea at low concentration) and ingredients that repair the barrier (ceramides, cholesterol, fatty acids).
• Gentle cleansing, no alkaline soap.
• Mind the environment: heating and air conditioning dry out the skin.
• The response is quick, within hours to days.

Expression lines

• Topical retinoids: they are the actives with the best evidence for fine wrinkles. Tretinoin, a prescription retinoid, has improved photoageing in controlled trials since the late 1980s (Weiss et al., 1988). Retinol, available over the counter, is gentler; in a trial in elderly people, 0.4% retinol improved fine wrinkles and increased collagen production after 24 weeks (Kafi et al., 2007). Retinoids are contraindicated in pregnancy.
• Daily sunscreen: it does not erase lines, but it slows the breakdown of the collagen that would make them static.
• Botulinum toxin: temporarily relaxes the muscle and softens the line. In Portugal, it is a prescription medicine and a medical act. It has an approved indication for the lines between the eyebrows, crow's feet and the forehead (depending on the product); in other areas, use is outside the approved indications. The effect usually lasts 3 to 4 months.
• Creams that promise the effect of toxin: there is no evidence that topical products relax muscles in a comparable way.

Static wrinkles

• Topical retinoids and sunscreen remain the basis, but the effect is slower and partial.
• Treatments that stimulate collagen, decided at consultation: medium peels, microneedling, lasers and other technologies, with variable results and different recovery times.
• Hyaluronic acid filler, in selected deep wrinkles. It is a medical act.
• Botulinum toxin, when there is still a dynamic component.

Grooves and folds

• Surface care helps skin quality, but does little for the groove itself.
• The effective options work at depth (volume replacement, firming technologies) and require medical assessment.

Sleep lines

• Sleeping on your back, when possible, is the only measure aimed at the cause.
• Smooth-fabric pillowcases and pillows designed to reduce compression are a reasonable option, although with little formal evidence.

Ingredients with more limited evidence

Vitamin C, niacinamide, peptides and growth factors have promising studies, generally small and short-term. They can complement a routine, but do not replace retinoids and sunscreen (Mukherjee et al., 2006).

Prevention: what has the most impact

The prevention with the best evidence is also the simplest. In a randomised trial in Australia, published in 2013, 903 adults under 55 were divided between using sunscreen every day or only when they chose to. After four and a half years, the daily-use group was 24% less likely to show worsening skin ageing (Hughes et al., 2013). No anti-wrinkle cream has a study of this kind and duration.

The measures that make the most difference:

• Broad-spectrum sunscreen, every day, even in winter and under cloudy skies.
• Do not smoke. Tobacco accelerates skin ageing independently of the sun.
• Sunglasses, which reduce squinting and protect the eye area.
• Skin hydration and barrier care.
• Topical retinoid from an age at which it makes sense for you, with gradual adaptation.
• Enough sleep and, if possible, on your back.

Expressions are part of who we are. There is no reason to smile less. What can be controlled is the rest.

At Luxmed, the skin assessment begins by understanding what type of lines you have and what causes them. From there, a plan is defined: home care, in-clinic skin treatments and, when indicated, referral for medical assessment.

This article is for information purposes and does not replace a medical consultation. The results of any treatment vary from person to person.

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