Psycholinguistics/DownsSyndromeLanguage

Description
Down Syndrome was first described in 1866 by Langdon Down. By the early 1930’s it was recognized at a chromosomal abnormality and was one of the first conditions to be examined chromosomally using detailed analysis of human chromosomes. 98% of all people with Down’s syndrome have Trisomy 21, resulting from a meiotic nondisjuncture of the chromosome on the 21st pair. .The risk of having a child with Trisomy 21 increase with maternal age. Robertsonian Traslocation accounts for approximately 4% of peoples with Down’s syndrome. The occurs when part of chromosome 21 attaches to another chromosome (Martin et al., 2009). In this case the child would have 46 chromosomes which is the number typically developing children have but, unlike Trisomy 21 where the child would have 47. Maternal age does not increase the risk of Robertsonian Traslocation, however, it has a seemingly high rate of recurrence when a parent is a carrier of the translocation. Lastly, there is Mosaic Down Syndrome, which occurs when some cells include an extra copy of chromosome 21 (Martin et al., 2009). Mosacism only accounts for 2% of Down syndrome. In Mosaic Down Syndrome, the phenotype is similar to trisomy 21, but is typically milder and patients with this represent the more clinically severe cases. All combined, Down syndrome occurs in about 1 in 800 live births and can happen in any race( Thomson & Thompson, 2007). Patterson and Lott (2008) suggest that maternal age has been shown to increase the risk of Down’s syndrome, with exception to the $5 with Robertsonian Traslocation, and can be tested for prenatally using amniocentesis and chorionic villus sampling. Thompson & Thompson (2007) state that one defining feature of Down syndrome is mental retardation, along with dysmorphic features.

Physical Attributes and Cognitive Abilities
The expression of the extra chromosome on the 21st pair is evident on specific physical characteristics, especially of the face. An individual with Down syndrome typically has, a round face, a flattened skull, and extra fold of skin over the eyelids, which causes a significant slant and a protruding or oversized tongue (macrogolssia) (Santrock, 2010). Also, they usually have shorter limbs and only two joints in their baby finger along with a single transverse palmar crease in their palm. The feet show a wide gap in the first and second toes with a furrow extending proximally on the plantar surface. Also, the neck is typically short with loose skin over the nape and there are Brushfield spots around the iris. (Thompson & Thompson, 2007) Children with Down Syndrome have poor muscle tone and often health consequences. Gardiner et al., (2010) suggest that people with Down Syndrome have reduced brain volume, specifically in the frontal, temporal lobes and cerebellum. However it seems the parahippocamal gyrus, which play a role in the ability to learn new representations of environmental information, is larger (Kolb and Whishaw, 2009). Thompson (2007) states that the developmental delay in Down syndrome is not usually evident till after the first year, where when they are tested, their IQ is 30 to 60. LOOK AT DEVELOPMENT TEXTBOOK. FIND PICTURE

Language Development in children with Down's Syndrome compared to typically developing children
The main difference between typically-developing children and children with Down Syndrome, in terms of language development is the rate at which language develops. For example, what would normally take a typically-developing child 30 months to learn would take 12 years for a child with Down syndrome. Compared to typically-developing children where first words occur around 12 months, children with Down syndrome do not begin to speak until around 24 months. Gleason and Ratner (2009) state that on average a child with Down syndrome is 20 months behind typically-developing children by age three and more than 24 months behind by age 4.The areas of language development that children with Down syndrome lag behind in are, expressive syntactic development, grammatical comprehension, verbal working memory and unsupported narrative tasks (Gleason and Ratner, 2009). Although children with Down syndrome may be behind typically-developing children, they still do develop language and because of more life experience, compared to other children or adolescents with the same mental age, they do end up showing a strong receptive vocabulary (Gleason and Ratner, 2009).

Cleland et al. (2009) notes that individuals with Down syndrome have differences in their anatomy that make it difficult for them to produce the correct phonemes. Such differences include a smaller than average oral cavity, hypotonia of the muscles around the mouth, fusion of the lip muscles and extra lip musculature. This leads to a problem with articulation, especially with fricatives

Language Characteristics of Down's Syndrome
Estigarribia B., Klusek J., Martin G., Roberts J., (2009) Language characteristics of individuals with down syndrome. Top lang Disorders. Vol. 29 No. 2 pp. 112-132.Wolters Kluwer Health | Lippincott Williams & Wilkins

-poor expressive language,especially phonology and syntax

- categorical, medical model of language development

-cognitive–behavioralphenotype

-2/3 of children with DS also have hearing loss

-otitis media, more susceptible 96% Patterson and Lott (2008) hearing loss could hinder language development, especially comprehension of grammatical morphemes

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Interventions
Articulation Disorders in Down’s Syndrome; Visual Leaning with Electropalatography Cleland, Timmins, Wood, Hardcastle & Wishart (2009)