Stuttering Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.Anti-spam check. Do not fill this in! ==Causes== The cause of developmental stuttering is complex and thought to be neurological with a genetic factor.<ref name=":4">{{Cite book|title=A handbook on stuttering|last1=Bloodstein|first1=Oliver|last2=Ratner|first2=Nan Bernstein|publisher=Cengage Learning|year=2007|isbn=978-1-4180-4203-5|pages=142}}</ref><ref>{{Cite web|date=2019-08-16|title=NIH study in mice identifies type of brain cell involved in stuttering|url=https://www.nidcd.nih.gov/news/2019/nih-study-mice-identifies-type-brain-cell-involved-stuttering|access-date=2021-05-16|website=NIDCD|language=en}}</ref> A variety of hypotheses and theories suggest multiple factors contributing to stuttering. There is strong evidence that stuttering has a genetic basis.<ref name="Guitar5β6">{{harvnb|Guitar|2005|pp= 5β6}}</ref> Children who have [[First-degree relative|first-degree relatives]] who stutter are three times as likely to develop a stutter.<ref>{{harvnb|Ward|2006|p= 11}}</ref> In a 2010 article, three genes were found by [[Dennis Drayna]] and team to correlate with stuttering: [[GNPTAB]], [[GNPTG]], and [[NAGPA]]. Researchers estimated that alterations in these three genes were present in 9% of those who have a family history of stuttering.<ref>{{Cite journal|last1=Kang|first1=Changsoo|last2=Riazuddin|first2=Sheikh|last3=Mundorff|first3=Jennifer|last4=Krasnewich|first4=Donna|last5=Friedman|first5=Penelope|last6=Mullikin|first6=James C.|last7=Drayna|first7=Dennis|date=2010-02-25|title=Mutations in the Lysosomal EnzymeβTargeting Pathway and Persistent Stuttering|journal=New England Journal of Medicine |language=EN |volume=362 |issue=8 |pages=677β685 |doi=10.1056/nejmoa0902630|issn=0028-4793 |pmc=2936507 |pmid=20147709}}</ref><ref>{{cite web |url=http://children.webmd.com/news/20100210/genetic-mutations-linked-to-stuttering |title=Genetic Mutations Linked to Stuttering |publisher=Children.webmd.com |date=February 10, 2010 |access-date=August 13, 2012 |url-status=live |archive-url=https://web.archive.org/web/20121112104541/http://children.webmd.com/news/20100210/genetic-mutations-linked-to-stuttering |archive-date=November 12, 2012 }}</ref><ref name="west">{{cite journal |last1=West | first1=R.|last2=Nelson|first2=S.|last3=Berry|first3=M.|year = 1939 |title = The heredity of stuttering |journal= Quarterly Journal of Speech |issue=1 |pages=23β30 |doi=10.1080/00335633909380434 |volume=25}}</ref> There is evidence that stuttering is more common in children who also have concurrent speech, language, learning or motor difficulties. For some people who stutter, congenital factors may play a role. In others, there could be added impact due to stressful situations.<ref name="Guitar5β6"/> There is evidence for structural and functional differences in the brains of stutterers. Research is complicated by the possibility that such differences could be the consequences of stuttering rather than a cause.<ref name="watkins">{{cite journal |vauthors=Watkins KE, Smith SM, Davis S, Howell P |title=Structural and functional abnormalities of the motor system in developmental stuttering |journal=Brain |volume=131 |issue=Pt 1 |pages=50β9 |date=January 2008|pmid=17928317 |pmc=2492392 |doi=10.1093/brain/awm241}}</ref><ref name="chang">{{cite journal |author= Soo-Eun, Chang|title= Brain anatomy differences in childhood stuttering |journal=[[NeuroImage (journal)|NeuroImage]] |year=2007 }}</ref>{{Obsolete source|reason=This source is from 2007, and significantly more research has been done|date=February 2024}} Other much less common causes of stuttering include neurogenic stuttering (stuttering that occurs secondary to brain damage, such as after a stroke) and psychogenic stuttering (stuttering related to a psychological condition).<ref name="Sander and Osborne" /> ===History of causes=== Auditory processing deficits have also been proposed as a cause of stuttering. Stuttering is possibly less prevalent in deaf and hard-of-hearing individuals,<ref>{{harvnb|Ward|2006|pp= 46β7}}</ref> and stuttering is occasionally reduced when auditory feedback is altered, such as by [[Auditory masking|masking]], [[delayed auditory feedback]] (DAF), or frequency altered feedback.<ref>{{harvnb|Ward|2006|p= 58}}</ref> There is evidence of differences in linguistic processing between people who stutter and people who do not.<ref>{{harvnb|Ward|2006|p= 43}}</ref> Brain scans of adult stutterers have found greater activation of the right hemisphere, which is associated with emotions, than of the left hemisphere, which is associated with speech. In addition, reduced activation in the left auditory cortex has been observed.<ref name="gordon"/> The ''capacities and demands'' model has been proposed to account for the heterogeneity of the disorder. In this approach, speech performance varies depending on the ''capacity'' that the individual has for producing fluent speech, and the ''demands'' placed upon the person by the speaking situation. Demands may be increased by internal factors or inadequate language skills or external factors. In stuttering, the severity of the disorder is seen as likely to increase when demands placed on the person's speech and language system exceed their capacity to deal with these pressures.<ref>{{harvnb|Ward|2006|pp= 16β21}}</ref> However, the precise nature of the capacity or incapacity has not been delineated. Another theory is that adults who stutter have elevated levels of the neurotransmitter [[dopamine]], and have thus found [[dopamine antagonist]]s that reduce stuttering.<ref name=":4">{{Cite book|title=A handbook on stuttering|last1=Bloodstein|first1=Oliver|last2=Ratner|first2=Nan Bernstein|publisher=Cengage Learning|year=2007|isbn=978-1-4180-4203-5|pages=142}}</ref> Overactivity of the midbrain has been found at the level of the substantia nigra extended to the red nucleus and subthalamic nucleus, which all contribute to the production of dopamine.<ref name=watkins /> However, increased dopamine does not imply increased excitatory function since dopamine's effect can be both excitatory or inhibitory depending upon which dopamine receptors have been stimulated. {{main|Dopamine hypothesis of stuttering }} It was once thought that forcing a left-handed student to write with their right-hand caused stuttering due to [[bias against left-handed people]], but this myth died out.<ref>{{cite journal|pmc=1591462|first=Ruth|last=Lewis|date=May 1949|pmid=18125462|volume=60|issue=5|journal=Can Med Assoc J|pages=497β500|title=The psychological approach to the preschool stutterer}}</ref><ref>{{cite journal|url=http://jhered.oxfordjournals.org/content/24/10/387.full.pdf|title=LEFT-HANDEDNESS AND STUTTERING|first1=Bryng|last1=Bryngelson|first2=Thomas B.|last2=Clark|journal=The Journal of Heredity|year=1933|volume=24|issue=10|pages=387β390|access-date=January 3, 2011}}{{dead link|date=May 2021|bot=medic}}{{cbignore|bot=medic}}</ref><ref>{{cite journal|author1=Johnson, W. |author2=L. Duke |year=1935|title=Changes in handedness associated with onset or disappearance of stuttering; sixteen cases|journal=Journal of Experimental Education|volume=4|pages=112β132|doi=10.1080/00220973.1935.11010003 }}</ref> Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here. You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see Christianpedia:Copyrights for details). Do not submit copyrighted work without permission! Cancel Editing help (opens in new window) Discuss this page