Editing Down syndrome (section)

===Neurological===
[[File:A boy with Down syndrome using cordless drill to assemble a book case.jpg|upright=1.2|thumb|A boy with Down syndrome using a cordless drill to assemble a book case]]
This syndrome causes about a third of cases of intellectual disability.<ref name=Steph2010/> Many developmental milestones are delayed with the ability to crawl typically occurring around 8–22 months rather than 6–12 months, and the ability to walk independently typically occurring around 1–4 years rather than 9–18 months.<ref>{{Cite web |title=Early Development for Children with Down Syndrome |url=https://www.cambscommunityservices.nhs.uk/Bedfordshire/services/occupational-therapy/ot-leaflets/down-syndrome |access-date=28 March 2023 |website=INHS Cambridgeshire Community Services NHS Trust}}</ref> Walking is acquired in 50% of children after 24 months.<ref>{{cite journal | vauthors = Winders P, Wolter-Warmerdam K, Hickey F | title = A schedule of gross motor development for children with Down syndrome | journal = Journal of Intellectual Disability Research | volume = 63 | issue = 4 | pages = 346–356 | date = April 2019 | pmid = 30575169 | doi = 10.1111/jir.12580 | s2cid = 58592265 }}</ref>

Most individuals with Down syndrome have mild (IQ: 50–69) or moderate (IQ: 35–50) [[intellectual disability]] with some cases having severe (IQ: 20–35) difficulties.<ref name=Wei2010/><ref name=Reil2012>{{cite journal | vauthors = Reilly C | title = Behavioural phenotypes and special educational needs: is aetiology important in the classroom? | journal = Journal of Intellectual Disability Research | volume = 56 | issue = 10 | pages = 929–946 | date = October 2012 | pmid = 22471356 | doi = 10.1111/j.1365-2788.2012.01542.x | doi-access = free }}</ref> Those with mosaic Down syndrome typically have IQ scores 10–30 points higher than that.<ref>{{cite book|title=Children with disabilities|year=2005|publisher=Paul H. Brookes|location=Baltimore [u.a.]|isbn=978-1-55766-581-2|page=308|url=https://books.google.com/books?id=P65sAAAAMAAJ&q=IQ+%22mosaic+down+syndrome%22|edition=5th| veditors = Batshaw M |url-status=live|archive-url=https://web.archive.org/web/20170123082658/https://books.google.com/books?id=P65sAAAAMAAJ&q=IQ+%22mosaic+down+syndrome%22|archive-date=2017-01-23}}</ref> As they age, the gap tends to widen between people with Down syndrome and their same-age peers.<ref name=Reil2012/><ref>{{cite journal | vauthors = Patterson T, Rapsey CM, Glue P | title = Systematic review of cognitive development across childhood in Down syndrome: implications for treatment interventions | journal = Journal of Intellectual Disability Research | volume = 57 | issue = 4 | pages = 306–318 | date = April 2013 | pmid = 23506141 | doi = 10.1111/j.1365-2788.2012.01536.x }}</ref>

Commonly, individuals with Down syndrome have better language understanding than ability to speak.<ref name=Hick2012/><ref name=Reil2012/> [[Babbling]] typically emerges around 15 months on average.<ref>{{cite journal | vauthors = Windsperger K, Hoehl S | title = Development of Down Syndrome Research Over the Last Decades-What Healthcare and Education Professionals Need to Know | journal = Frontiers in Psychiatry | volume = 12 | pages = 749046 | date = 2021 | pmid = 34970162 | pmc = 8712441 | doi = 10.3389/fpsyt.2021.749046 | doi-access = free }}</ref> 10–45% of those with Down syndrome have either a [[stutter]] or [[cluttering|rapid and irregular speech]], making it difficult to understand them.<ref>{{cite journal | vauthors = Kent RD, Vorperian HK | title = Speech impairment in Down syndrome: a review | journal = Journal of Speech, Language, and Hearing Research | volume = 56 | issue = 1 | pages = 178–210 | date = February 2013 | pmid = 23275397 | pmc = 3584188 | doi = 10.1044/1092-4388(2012/12-0148) }}</ref> After reaching 30&nbsp;years of age, some may lose their ability to speak.<ref name=Malt2013/>

They typically do fairly well with social skills.<ref name=Hick2012/> Behavior problems are not generally as great an issue as in other syndromes associated with intellectual disability.<ref name=Reil2012/> In children with Down syndrome, [[mental illness]] occurs in nearly 30% with [[autism spectrum|autism]] occurring in 5–10%.<ref name=Nelson2011/> People with Down syndrome experience a wide range of emotions.<ref>{{cite book| vauthors = McGuire D, Chicoine B |title=Mental Wellness in Adults with Down Syndrome|year=2006|publisher=Woodbine House, Inc.|location=Bethesday, MD|isbn=978-1-890627-65-2|page=49}}</ref> While people with Down syndrome are generally happy,<ref>{{cite book| vauthors = Margulies P |title=Down syndrome|year=2007|publisher=Rosen Pub. Group|location=New York|isbn=978-1-4042-0695-3|page=[https://archive.org/details/downsyndrome0000marg/page/5 5]|url=https://archive.org/details/downsyndrome0000marg|url-access=registration|edition=1st}}</ref> symptoms of [[Depression (mood)|depression]] and [[anxiety (mood)|anxiety]] may develop in early adulthood.<ref name=Malt2013/>

Children and adults with Down syndrome are at increased risk of [[epileptic seizures]], which occur in 5–10% of children and up to 50% of adults.<ref name=Malt2013/> This includes an increased risk of a specific type of seizure called [[infantile spasms]].<ref name=Hick2012/> Many (15%) who live 40 years or longer develop [[Alzheimer's disease]].<ref>{{cite book|title=The 5-minute pediatric consult|year=2012|publisher=Wolters Kluwer Health/Lippincott Williams & Wilkins|location=Philadelphia|isbn=978-1-4511-1656-4|page=289|url=https://books.google.com/books?id=v7pbSFfMHCoC&pg=PA289|edition=6th | veditors = Schwartz MW |url-status=live|archive-url= https://web.archive.org/web/20170123083059/https://books.google.com/books?id=v7pbSFfMHCoC&pg=PA289|archive-date=2017-01-23}}</ref> In those who reach 60&nbsp;years of age, 50–70% have the disease.<ref name="Malt2013"/>

[[Down syndrome regression disorder]] is a sudden [[Regression (medicine)|regression]] with [[neuropsychiatric]] symptoms such as [[catatonia]], possibly caused by an autoimmune disease.<ref>{{Cite journal |last1=Santoro |first1=Jonathan D. |last2=Filipink |first2=Robyn A. |last3=Baumer |first3=Nicole T. |last4=Bulova |first4=Peter D. |last5=Handen |first5=Benjamin L. |date=2023-03-01 |title=Down syndrome regression disorder: updates and therapeutic advances |url=https://pubmed.ncbi.nlm.nih.gov/36705008 |journal=Current Opinion in Psychiatry |volume=36 |issue=2 |pages=96–103 |doi=10.1097/YCO.0000000000000845 |issn=1473-6578 |pmid=36705008}}</ref>  It primarily appears in teenagers and younger adults.<ref>{{Cite book |last1=Skoto |first1=Brian G. |chapter-url=https://books.google.com/books?id=KYUCEQAAQBAJ&dq=%22Down+syndrome+regression+disorder%22&pg=PT1514 |title=The 5-Minute Clinical Consult 2025 |last2=Roberts |first2=Michele |date=2024-02-28 |publisher=Lippincott Williams & Wilkins |isbn=978-1-9752-3473-7 |editor-last=Domino |editor-first=Frank J. |language=en |chapter=Down Syndrome}}</ref>