Editing Tourette syndrome (section)

== Classification ==
Most published research on Tourette syndrome originates in the United States; in international TS research and clinical practice, the ''[[Diagnostic and Statistical Manual of Mental Disorders]]'' (DSM) is preferred over the [[World Health Organization]] (WHO) classification,<ref name= EuropeanPartI/><ref name= DSMAppraisal /><ref name=Liu2020/> which is criticized in the 2021 ''European Clinical Guidelines.<ref name=EuropeanGuidelines/>

In the fifth version of the DSM ([[DSM-5]]), published in 2013, Tourette syndrome is classified as a [[motor disorder]] (a disorder of the [[nervous system]] that causes abnormal and involuntary movements). It is listed in the [[neurodevelopmental disorder]] category.<ref name=DSM5 /> Tourette's is at the more severe end of the [[spectrum disorder|spectrum]] of [[tic disorder]]s; its diagnosis requires multiple motor [[tic]]s and at least one vocal tic to be present for more than a year. Tics are sudden, repetitive, nonrhythmic movements that involve discrete muscle groups,<ref>{{cite journal |vauthors=Martino D, Hedderly T |title=Tics and stereotypies: A comparative clinical review |journal=Parkinsonism Relat. Disord. |volume=59 |pages=117–124 |date=February 2019 |pmid=30773283 |doi=10.1016/j.parkreldis.2019.02.005 |s2cid=73486351 |type= Review}}</ref> while vocal (phonic) tics involve [[larynx|laryngeal]], [[pharynx|pharyngeal]], oral, nasal or respiratory muscles to produce sounds.<ref name=Martino2018>{{cite journal |vauthors=Martino D, Pringsheim TM |title=Tourette syndrome and other chronic tic disorders: an update on clinical management |journal=Expert Rev Neurother |volume=18 |issue=2 |pages=125–137 |date=February 2018 |pmid=29219631 |doi=10.1080/14737175.2018.1413938 |s2cid=205823966 |type=Review}}</ref><ref>{{cite journal |vauthors= Jankovic J |url= http://practicalneurology.com/pdfs/pn0917_SF_Tourettes.pdf |title= Tics and Tourette syndrome |journal= Practical Neurology |date= September 2017 |pages= 22–24 |access-date= March 24, 2019 |archive-url= https://web.archive.org/web/20190324192032/http://practicalneurology.com/pdfs/pn0917_SF_Tourettes.pdf |archive-date= March 24, 2019 |url-status= dead }}</ref> The tics must not be explained by other medical conditions or substance use.<ref name= Fernandez />

Other tic disorders include persistent (chronic) motor or vocal tics, in which one type of tic (motor or vocal, but not both) has been present for more than a year; and provisional tic disorder, in which motor or vocal tics have been present for less than one year.<ref name= Dale2017 />{{sfnp|Sukhodolsky|Gladstone|Kaushal|Piasecka|2017|p= 242}} The fifth edition of the DSM replaced what had been called ''transient tic disorder'' with ''provisional tic disorder'', recognizing that "transient" can only be defined in retrospect.<ref name="DSMAppraisal">{{cite journal | vauthors = Robertson MM, Eapen V | title = Tourette's: syndrome, disorder or spectrum? Classificatory challenges and an appraisal of the DSM criteria | journal = Asian Journal of Psychiatry | volume = 11 | pages = 106–113 | date = October 2014 | pmid = 25453712 | doi = 10.1016/j.ajp.2014.05.010 | name-list-style = vanc | type = Review | author-link2 = Valsamma Eapen }}</ref><ref name=DSMV>{{cite web |url= http://www.dsm5.org/proposedrevision/Pages/NeurodevelopmentalDisorders.aspx |title= Neurodevelopmental disorders |publisher= [[American Psychiatric Association]] |access-date= December 29, 2011|archive-url= https://web.archive.org/web/20110510131026/http://www.dsm5.org/proposedrevision/Pages/NeurodevelopmentalDisorders.aspx |archive-date= May 10, 2011 }}</ref><ref name=Highlights>{{cite web |url= http://www.psychiatry.org/File%20Library/Practice/DSM/DSM-5/Changes-from-DSM-IV-TR--to-DSM-5.pdf |title= Highlights of changes from DSM-IV-TR to DSM-5 |publisher= American Psychiatric Association |date= 2013 |access-date= June 5, 2013|archive-url= https://web.archive.org/web/20130203165749/http://www.psychiatry.org/File%20Library/Practice/DSM/DSM-5/Changes-from-DSM-IV-TR--to-DSM-5.pdf |archive-date= February 3, 2013 }}</ref> Some experts believe that TS and persistent (chronic) motor or vocal tic disorder should be considered the same condition, because vocal tics are also motor tics in the sense that they are muscular contractions of nasal or respiratory muscles.<ref name= EuropeanPartI/><ref name= PringHoller2019 />{{sfnp|Sukhodolsky|Gladstone|Kaushal|Piasecka|2017|p= 242}}

Tourette syndrome is defined only slightly differently by the WHO;<ref name= Hollis /><!-- p. 1.--><ref name= Liu2020>{{cite journal |vauthors=Liu ZS, Cui YH, Sun D, et al |title=Current status, diagnosis, and treatment recommendation for tic disorders in China |journal=Front Psychiatry |volume=11 |pages=774 |date=2020 |pmid=32903695 |pmc=7438753 |doi=10.3389/fpsyt.2020.00774 |quote= The CCMD-3, DSM-5, and ICD-11 diagnostic criteria for tics are almost the same. Currently, the DSM-5 is mostly used in clinical practice around the world, including China.|doi-access=free }}</ref> in its [[ICD-11]], the [[International Statistical Classification of Diseases and Related Health Problems]], Tourette syndrome is classified as a disease of the nervous system and a neurodevelopmental disorder,<ref name=Reed2019>{{cite journal |vauthors=Reed GM, First MB, Kogan CS, et al|title=Innovations and changes in the ICD-11 classification of mental, behavioural and neurodevelopmental disorders |journal=World Psychiatry |volume=18 |issue=1 |pages=3–19 |date=February 2019 |pmid=30600616 |pmc=6313247 |doi=10.1002/wps.20611 |quote= Finally, chronic tic disorders, including Tourette syndrome, are classified in the ICD-11 chapter on diseases of the nervous system, but are cross-listed in the grouping of neurodevelopmental disorders because of their high co-occurrence (e.g., with ADHD) and typical onset during the developmental period.}}</ref><ref name=ICD-11>{{cite web |url= https://icd.who.int/browse11/l-m/en#/http://id.who.int/icd/entity/119340957 |title= 8A05.00 Tourette syndrome |publisher= World Health Organization |access-date= March 28, 2022 |quote= Diseases of the nervous system --> Tic disorders: "onset during the developmental period" |archive-date= August 1, 2018 |archive-url= https://archive.today/20180801205234/https://icd.who.int/browse11/l-m/en%23/http://id.who.int/icd/entity/294762853#/http://id.who.int/icd/entity/119340957 |url-status= live }}</ref> and only one motor tic and one or more vocal tics are required for diagnosis.<ref name=Ueda2021>{{cite journal |vauthors=Ueda K, Black KJ |title=Recent progress on Tourette syndrome |journal=Fac Rev |volume=10 |pages=70 |date=2021 |pmid=34557874 |pmc=8442002 |doi=10.12703/r/10-70 |doi-access=free }}</ref> Older versions of the ICD called it "combined vocal and multiple motor tic disorder [de la Tourette]".<ref>{{cite web |date= 2010 |url=https://icd.who.int/browse10/2019/en#/F95.2 |publisher= [[World Health Organization]] |title= International Statistical Classification of Diseases and Related Health Problems 10th Revision: Chapter V: Mental and behavioural disorders |access-date= August 7, 2020|archive-date= March 31, 2020 |archive-url= https://archive.today/20200331004754/https://icd.who.int/browse10/2019/en%23/U07.1#/F95.2 |url-status= live}} See also [http://apps.who.int/classifications/apps/icd/icd10online/?gf90.htm+f950 ICD version 2007.] {{Webarchive|url=https://web.archive.org/web/20120304043704/http://apps.who.int/classifications/apps/icd/icd10online/?gf90.htm+f950 |date=March 4, 2012 }}</ref>

Genetic studies indicate that tic disorders cover a spectrum that is not recognized by the clear-cut distinctions in the current diagnostic framework.<ref name= Fernandez /> Since 2008, studies have suggested that Tourette's is not a unitary condition with a distinct mechanism, as described in the existing classification systems. Instead, the studies suggest that subtypes should be recognized to distinguish "pure TS" from TS that is accompanied by [[attention deficit hyperactivity disorder]] (ADHD), [[obsessive–compulsive disorder]] (OCD) or other disorders, similar to the way that subtypes have been established for other conditions, such as [[Type 1 diabetes|type 1]] and [[type 2 diabetes]].<ref name= Hollis /><!-- p. 4 --><ref name= Fernandez /><ref name= Ueda2021/> Elucidation of these [[phenotype|subtypes]] awaits fuller understanding of the [[genetics|genetic]] and other causes of tic disorders.<ref name= DSMAppraisal />