Editing Wrinkle

{{Short description|Crease on otherwise smooth surface}}
{{Redirect|Wrinkles}}
{{For|the writer and filmmaker|Margaret Wrinkle}}
[[File:Old Bangladeshi drinking tea cropped.jpg|thumb|right|Wrinkles on the face and hands are a typical sign of aging]]

A '''wrinkle''', also known as a '''rhytid''', is a fold, ridge or crease in an otherwise smooth surface, such as on [[skin]] or [[fabric]]. [[Skin fold|Skin wrinkles]] typically appear as a result of [[Senescence|ageing]] processes such as [[glycation]],<ref>{{cite journal |last=Danby |first=FW |title=Nutrition and aging skin: sugar and glycation|journal=Clin Dermatol|date=Jul–Aug 2010|volume=28|issue=4|series=4|pages=409–411|doi=10.1016/j.clindermatol.2010.03.018|pmid=20620757}}</ref>  habitual sleeping positions,<ref>{{cite web|last=American Academy of Dermatology |title=Causes of Aging |url=http://www.skincarephysicians.com/agingskinnet/basicfacts.html|work=AgingSkinNet|publisher=American Academy of Dermatology|access-date=5 March 2013}}</ref> loss of body mass, [[sun]] damage,<ref>[https://www.webmd.com/beauty/cosmetic-procedures-wrinkles Cosmetic Procedures for Wrinkles]</ref> or temporarily, as the result of prolonged immersion in [[water]]. Age wrinkling in the skin is promoted by habitual facial expressions, aging, sun damage, smoking, poor hydration, and various other factors.<ref>Anderson, Laurence. 2006. ''Looking Good, the Australian guide to skin care, cosmetic medicine and cosmetic surgery''. AMPCo. Sydney. {{ISBN|0-85557-044-X}}.</ref> In humans, it can also be prevented to some degree by avoiding excessive solar exposure and through [[dieting|diet]] (in particular through consumption of [[carotenoid|carotenoids]], [[tocopherol|tocopherols]] and [[flavonoid|flavonoids]], vitamins (A, C, D and E), essential omega-3-fatty acids, certain proteins and lactobacilli).<ref>{{cite journal | pmc=3583891 | year=2012 | last1=Schagen | first1=S. K. | last2=Zampeli | first2=V. A. | last3=Makrantonaki | first3=E. | last4=Zouboulis | first4=C. C. | title=Discovering the link between nutrition and skin aging | journal=Dermato-Endocrinology | volume=4 | issue=3 | pages=298–307 | doi=10.4161/derm.22876 | pmid=23467449 }}</ref>

== Skin ==
{{Main|Skin fold}}

=== Causes for aging wrinkles ===
[[File:Nose_%E2%80%93_Caisa.jpg|thumb|upright|A woman of European origin with facial wrinkles]]
Development of facial wrinkles is a kind of [[fibrosis]] of the skin. Misrepair-accumulation aging theory suggests that wrinkles develop from incorrect repairs of injured elastic fibers and collagen fibers.<ref>{{cite arXiv |eprint=0904.0575 |title= Aging as a consequence of Misrepair—a novel theory of aging |last1=Wang |first1=Jicun |last2=Michelitsch |first2=Thomas |last3=Wunderlin |first3=Arne |last4=Mahadeva |first4=Ravi |year=2009 |class= q-bio.TO }}</ref><ref>{{cite arXiv |eprint=1503.07163 |title= Aging as a process of accumulation of Misrepairs |last1=Wang-Michelitsch |first1=Jicun |last2=Michelitsch |first2=Thomas |year=2015 |class= q-bio.TO }}</ref><ref>{{cite arXiv |eprint=1505.01376 |title=Tissue fibrosis: a principal evidence for the central role of Misrepairs in aging |last1=Wang-Michelitsch |first1=Jicun |last2=Michelitsch |first2=Thomas |year=2015 |class=q-bio.TO }}</ref> Repeated extensions and compressions of the skin cause repeated injuries of extracellular fibers in derma. During the repairing process, some of the broken elastic fibers and collagen fibers are not regenerated and restored but replaced by altered fibers. When an elastic fiber is broken in an extended state, it may be replaced by a "long" collagen fiber. Accumulation of "long" collagen fibers makes part of the skin looser and stiffer, and as a consequence, a big fold of skin appears. When a "long" collagen is broken in a compressed state, it may be replaced by a "short" collagen fiber. The "shorter" collagen fibers will restrict the extension of "longer" fibers, and make the “long" fibers in a folding state permanently. A small fold, namely a permanent wrinkle, then appears.

=== Sleep wrinkles ===

Sleep wrinkles are created and reinforced when the face is compressed against a pillow or bed surface in side or stomach sleeping positions during sleep.<ref>{{cite journal|last=Sarifakioglu|first=Nedim|author2=Terzioglu, A. |author3=Ates, L. |author4=Aslan, G. |title=A New Phenomenon: 'Sleep Lines' on the Face|journal=Scan J Plast Reconstr Surg Hand Surg|year=2004|volume=38|pages=244–247|doi=10.1080/02844310410027257|pmid=15370809|issue=4|s2cid=25307487}}</ref> They appear in predictable locations due to the underlying [[superficial muscular aponeurotic system|superficial musculoaponeurotic system]] (SMAS), and are usually distinct from wrinkles of facial expression.<ref>{{cite journal|last=Fulton|first=James E.|author2=Gaminchi, F. |title=Sleep Lines|journal=Dermatol Surg|year=1999|volume=25|pages=59–62|doi=10.1046/j.1524-4725.1999.08073.x|pmid=9935097|issue=1}}</ref> As with wrinkles of facial expression, sleep wrinkles can deepen and become permanent over time, unless the habitual sleeping positions which cause the wrinkles are altered.<ref>{{cite journal|last=Sarifakioglu|first=Nedim|author2=Terzioglu, A. |author3=Ates, L. |author4=Aslan, G. |title=A New Phenomenon: 'Sleep Lines' on the Face|journal=Scan J Plast Reconstr Surg Hand Surg|year=2004|volume=38|pages=244–247 [246]|doi=10.1080/02844310410027257|pmid=15370809|issue=4|s2cid=25307487}}</ref>

===Water-immersion wrinkling===<!-- This section is linked from [[Water aging]] -->
[[File:Wrinkly fingers.jpg|thumb|left|A wrinkled finger after a warm bath]]
The wrinkles that occur in skin over prolonged exposure to water are sometimes referred to as ''pruney fingers'' or water aging. This is a temporary [[skin condition]] where the skin on the palms of the hand or feet becomes wrinkly. This wrinkling response may have imparted an evolutionary benefit by providing improved traction in wet conditions,<ref>{{cite journal | doi= 10.1159/000328223 | title= Are Wet-Induced Wrinkled Fingers Primate Rain Treads? |author1=Mark Changizi |author2=Romann Weber |author3=Ritesh Kotecha |author4=Joseph Palazzo | journal= Brain, Behavior and Evolution |  year= 2011 | pmid= 21701145 | volume=77 | issue=4 | pages=286–90| doi-access=free }}</ref> and a better grasp of wet objects.<ref>{{cite journal|last=Kareklas|first=Kyriacos|author2=Nettle, Daniel |author3=Smulders, Tom V |title=Water-induced finger wrinkles improve handling of wet objects|journal=Biol. Lett.|date=January 9, 2013|volume=9|issue=2|doi=10.1098/rsbl.2012.0999|page=20120999|pmid=23302867|pmc=3639753}}</ref> These results were called into question by a 2014 study that failed to reproduce any improvement of handling wet objects with wrinkled fingertips.<ref name=Haseleu>{{cite journal|doi=10.1371/journal.pone.0084949|title=Water-Induced Finger Wrinkles Do Not Affect Touch Acuity or Dexterity in Handling Wet Objects|year=2014|editor1-last=Goldreich|editor1-first=Daniel|last1=Haseleu|first1=Julia|last2=Omerbašić|first2=Damir|last3=Frenzel|first3=Henning|last4=Gross|first4=Manfred|last5=Lewin|first5=Gary R.|journal=PLOS ONE|volume=9|issue=1|pages=e84949|pmid=24416318|pmc=3885627|bibcode=2014PLoSO...984949H|doi-access=free}}</ref> However, a 2020 study of gripping efficiency found that wrinkles decreased the force required to grip wet objects by 20%, supporting the traction hypothesis.<ref name=Davis>{{cite bioRxiv |last1=Davis |first1=N.|date=8 November 2020 |title=Water-immersion finger-wrinkling improves grip efficiency in handling wet objects |biorxiv=10.1101/2020.11.07.372631}}</ref>

Prior to a 1935 study, the common explanation was based on water absorption in the [[keratin]]-laden [[epithelial]] skin when immersed in water,<ref>{{cite web|url=http://www.abc.net.au/science/k2/homework/s95618.htm |title=Dr Karl's Homework – Skin Wrinkles in Water (26/1/2000) |publisher=Abc.net.au |date=2000-01-26 |access-date=2019-04-30}}</ref> causing the skin to expand and resulting in a larger surface area, forcing it to wrinkle. Usually the tips of the fingers and toes are the first to wrinkle because of a thicker layer of keratin and an absence of hairs which secrete the protective oil called [[sebum]].

[[File:Adult sole showing water immersion wrinkling.JPG|thumb|upright|Adult sole showing water immersion wrinkling]]

In the 1935 study, however, Lewis and Pickering were studying patients with [[:wikt:palsy|palsy]] of the [[median nerve]] when they discovered that skin wrinkling did not occur in the areas of the patients' skin normally innervated by the damaged nerve.  This suggested that the nervous system plays an essential role in wrinkling, so the phenomenon could not be entirely explained simply by water absorption. Recent research shows that wrinkling is related to [[vasoconstriction]].<ref>{{cite journal | doi= 10.1002/mus.10323 | title= Water-immersion wrinkeling is due to vasoconstriction|author1=Einar P.V. Wilder-Smith |author2=Adeline Chow | journal=Muscle & Nerve| year=2003| pages=307–311| volume=27| issue=3| pmid=12635117| s2cid= 45193684| doi-access=free}}</ref><ref>{{cite journal | doi=10.1007/s10286-004-0172-4 | author=Einar P. V. Wilder-Smith| title=Water immersion wrinkling| journal=Clinical Autonomic Research| year=2004| pages=125–131| volume=14| issue=2 | pmid=15095056| s2cid=44938772}}</ref> Water probably initiates the wrinkling process by altering the balance of [[electrolytes]] in the skin as it diffuses into the hands and soles via their many sweat ducts. This could alter the stability of the membranes of the many neurons that synapse on the many blood vessels underneath skin, causing them to fire more rapidly.  Increased neuronal firing causes blood vessels to constrict, decreasing the amount of fluid underneath the skin.  This decrease in fluid would cause a decrease in tension, causing the skin to become wrinkly.<ref>{{cite book | title= Dermatotoxicology|author= H. Zhai, K.P. Whilem H. L. Maibach| year=2007| pages=280–281| issue=7}}</ref>

This insight resulted in bedside tests for nerve damage and vasoconstriction. Wrinkling is often scored with immersion of the hands for 30 minutes in water or [[EMLA]] cream with measurements steps of 5 minutes, and counting the number of visible wrinkles in time. Not all healthy persons have finger wrinkling after immersion, so it would be safe to say that sympathetic function is preserved if finger wrinkling after immersion in water is observed, but if the
fingers emerge smooth it cannot be assumed that there is a lesion to the autonomic supply or to the peripheral nerves of the hand.<ref>{{Cite journal | title=Finger wrinkling after immersion in water|author1=G Alvarez, J Eurolo |author2=P Canales| journal=British Medical Journal | year=1980| pages=586–587 | doi=10.1136/bmj.281.6240.586-a | volume=281 | issue=6240 | pmid=7427379 | pmc=1713922}}</ref>

=== Other animals with wrinkles ===
Examples of wrinkles can be found in various animal species that grow loose, excess skin, particularly when they are young. Several breeds of [[dog]], such as the [[Pug]] and the [[Shar Pei]], have been bred to exaggerate this trait. In dogs bred for [[dog fighting|fighting]], this is the result of selection for loose skin, which confers a protective advantage.<ref>{{cite book |title=The Dog Encyclopedia: The Definitive Visual Guide |date=15 August 2023 |publisher=Penguin |isbn=978-0-7440-8513-6 |page=84 |url=https://books.google.com/books?id=RC6uEAAAQBAJ&pg=PA84 |language=en}}</ref>

=== Techniques for reducing the appearance of aging wrinkles ===
[[File:Dr Braun Performs a Botox Injection (4035273577).jpg|thumb|upright|left|A man receiving a botox injection]]
Current evidence suggests that [[tretinoin]] decreases cohesiveness of follicular epithelial cells, although the exact mode of action is unknown. Additionally, tretinoin stimulates mitotic activity and increased turnover of follicular epithelial cells.<ref>{{cite journal| title=Topical retinoids in the treatment of photoaging|date=June 2005| pmid=17166212|vauthors=Stefanaki C, Stratigos A, Katsambas A | journal= J Cosmet Dermatol| volume=4| pages=130–4| doi=10.1111/j.1473-2165.2005.40215.x | issue=2|s2cid=44702740}}</ref> Tretinoin is better known by the [[brand name]] Retin-A.

Topical [[glycosaminoglycan]]s supplements can help to provide temporary restoration of enzyme balance to slow or prevent matrix breakdown and consequent onset of wrinkle formation. Glycosaminoglycans (GAGs) are produced by the body to maintain structural integrity in tissues and to maintain fluid balance. [[Hyaluronic acid|Hyaluronic]] acid is a type of GAG that promotes collagen synthesis, repair, and hydration. GAGs serve as a natural moisturizer and lubricant between epidermal cells to inhibit the production of matrix metalloproteinases (MMPs).

Dermal fillers are injectable products frequently used to correct wrinkles, and other depressions in the skin. They are often a kind of soft tissue designed to enable injection into the skin for purposes of improving the appearance. The most common products are based on [[hyaluronic acid]] and calcium hydroxylapatite.

[[Botulinum toxin]] is a [[neurotoxin]] protein produced by the bacterium ''[[Clostridium botulinum]]''. Botox is a specific form of botulinum toxin manufactured by [[Allergan]] for both therapeutic and cosmetic use. Besides its cosmetic application, Botox is used in the treatment of other conditions including migraine headache and cervical [[dystonia]] (spasmodic [[torticollis]]) (a neuromuscular disorder involving the head and neck).<ref>{{cite journal |vauthors=Brin MF, Lew MF, Adler CH, Comella CL, Factor SA, Jankovic J, O'Brien C, Murray JJ, Wallace JD, Willmer-Hulme A, Koller M | title=Safety and efficacy of NeuroBloc (botulinum toxin type B) in type A-resistant cervical dystonia | journal=Neurology | year=1999 | pages=1431–8 | volume=53 | issue=7 | pmid=10534247 | doi=10.1212/WNL.53.7.1431}}</ref>

Dysport, manufactured by Ipsen, received [[FDA]] approval and is now used to treat cervical dystonia as well as glabellar lines in adults.  In 2010, another form of botulinum toxin, one free of complexing proteins, became available to Americans. Xeomin received FDA approval for medical indications in 2010 and cosmetic indications in 2011.

Botulinum toxin treats wrinkles by immobilizing the muscles which cause wrinkles.  It is not appropriate for the treatment of all wrinkles; it is indicated for the treatment of glabellar lines (between the eyebrows) in adults.  Any other usage is not approved by the FDA and is considered [[off-label use]].

Laser resurfacing is FDA-cleared skin resurfacing procedure in which lasers are used to improve the condition of the skin.{{citation needed|date=March 2015}} Two types of lasers are used to reduce the appearance of fine lines and wrinkles on the face; [[laser ablation]], which removes thin layers of skin, and nonablative lasers that stimulate [[collagen]] production. Nonablative lasers are less effective than ablative ones but they are less invasive and  recovery time is short. After the procedure people experience temporary redness, itching and swelling.

== See also ==
* [[Botulinum toxin]]
* [[Injectable filler]]
* [[Wrinkly skin syndrome]]

== References ==
{{Reflist|30em}}

== External links ==
{{Wiktionary}}
{{Commons category|Wrinkles (skin)}}
* [https://www.nlm.nih.gov/medlineplus/skinaging.html Skin Ageing] at [[Medline]]

{{DEFAULTSORT:Wrinkle (Skin)}}
[[Category:Ageing]]
[[Category:Skin]]