Reading and reading-related skills in Williams and Down syndromes

1. Reading and reading-related skills in Williams and Down syndromes Yonata Levy Psychology Department and Hebrew University-Hadassah Medical School, Jerusalem

2. This work was supported by a grant from the Israel Science Foundation Work on Hebrew was done in collaboration with my students: Vered Antebi Shani Beiser Work with the American Williams syndrome group was done in collaboration with Jason Smith and Helen Tager-Flusberg We are grateful to the WS Associations in the US and in Israel and to the Down syndrome Association in Israel, but most of all we are grateful to the children and their families

3. The research question: Individuals with neurodevelopmental disorders that result in cognitive disabilities are often reading impaired But are they dyslexic?? The answer: If reading disorders in these populations present themselves along with the cluster of strengths and weaknesses that are characteristic of dyslexic children then the answer is YES If the profile is different then the answer is NO

4. What is dyslexia and what is it not Until the mid 90’ies dyslexia was considered a condition affecting typically developing children who, contrary to expectations, failed to acquire reading at the expected age, i.e. during the first years of elementary school Crucially, dyslexic children scored average or above average on IQ tests and were reading less well than predicted by their IQ Hence, there was a poorly understood discrepancy

5. According to the discrepancy definitionDyslexia is – (quoting) • . A disorder manifested by the difficulty in learning to read, despite conventional instruction, adequate intelligence and sociocultural opportunities. It is dependent upon fundamental cognitive disabilities which are frequently of constitutional nature • The condition we have when there is a clear discrepancy between the person’s reading ability and other intellectual abilities

6. Apart from ‘true dyslexics’, there are children who score below average on intelligence tests who do not read well The literature has referred to these children as ‘Garden variety poor readers’ In these children reading is one domain among many in which they perform at the lower tail of their age level hence, they are not dyslexic ‘Poor readers’ score low, but are still within one SD of the normal range IQ (>85)

7. What was the theoretical appeal of the discrepancy definition? It highlighted the specificity of dyslexia, and being ‘specific’ was equivalent to being ‘theoretically interesting’ Dyslexiahas been thought about as a specific reading disorder that is not related to the child’s general cognitive functioning

8. The discrepancy definition crucially depends upon 1. An effect of IQ on reading in the ‘poor readers’ but not in dyslexics 2. That there be Differences between the profiles characterizing dyslexic children and ‘garden variety poor readers’ What is the characteristic profile of dyslexia?

9. When the clinical picture is considered, Dyslexia is a mixed bag, but focusing on word readingthe following profile emerges • Deficits in phonological awareness tasks • Deficits in short term auditory memory • Correlations with rapid object naming • Correlations with vocabulary size Children with a • Correlations with syntax and morphology historyof SLI • Peripheral vision problems?? • Problems in processing temporally sequenced information??

10. Note – There has been relatively little research on reading in syndromic populations yet, reading difficulties in these populations can be easily accounted for within the discrepancy approach -- Mentally handicapped people have difficulties in reading because of their mental handicaps And this made research in this populations rather uninteresting and had an effect on intervention as well

11. However, research has provided little empirical support for the discrepancy hypothesis The profile that characterizes dyslexia is also characteristic of ‘garden variety poor readers’ and IQ does not correlate with RD within this group any more than it does in dyslexics

12. The research findings that forced a change in the definition of dyslexia reflected a wide consensus among researchers that the basic issues in RD relate to language and that performance on intelligence tests was not a key issue Since 1995, the definition of dyslexia considers it to be “a specific language-based disorder of constitutional origin, characterized by difficulties in single word decoding, usually reflecting insufficient phonological abilities” (Orton Society, 1995)

13. In the light of this definition, the research question that the current study addresses is the following: Are children with neuro-developmental syndromes, specifically children with Williams syndrome and children with Down syndrome, who experience reading difficulties, dyslexic?

14. Are they dyslexic – yes or no? In order for the answer to be YES, the reading difficulties seen in children with Williams syndrome or with Down syndrome should correlate with the familiar language measures and not co-varyaccording to IQ This work refers exclusively to decoding and will only look at word reading

15. Williams syndrome - WS

16. Williams syndrome (WS) → A rare genetic disorder (1:20,000) which is typically not familial → The clinical phenotype includes 50-70 IQ on average, short stature, unique facial features, high frequency of SVAS, hyper-acusis, hyper-calcemia, orthopedic problems and a typical gait → A FISH test reveals a micro-deletion on 7q11.23 with around 24 genes missing, including the ELN gene → Individuals with WS are very friendly, talkative, with no fear of strangers and with great love for music → WS cognitive profile is often described as unique – their expressive language is fluent and grammatical, their vocabulary is rich, their auditory short term memory is very good, their face processing is good but their visual-motor and motor integration skills are way below what is expected of their mental age

17. A recent MRI study by Galaburda and his team (2004) suggests that participants with WS have reduced thalamic and occipital lobe gray matter volumes and reduced gray matter density in subcortical and cortical regions comprising the human visual-spatial system, compared with controls The WS group also showed disproportionate increases in volume and gray matter density in several areas known to participate in emotion and face processing, including the amygdala, orbital and medial prefrontal cortices, anterior cingulate, insular cortex, and superior temporal gyrus

18. Down syndrome -DS

19. Down syndrome (DS) → A common neurogenetic disorder, 1:600 with equal frequency between males and females → DS occurs when there is duplication of chromosome 21 (trisomy 21) or part of it (mosaic) → The phenotype includes IQ 50-70 on average, unique facial features, cardiac problems, frequent otitis media, early signs of aging and high frequency of Alzheimer’s disease → The cognitive profile of individuals with DS is described as depressed across tasks, with specific deficits in language skills → Individuals with DS have poor auditory short term memory for words, poor vocabulary and even poorer syntax

20. Brain imaging studies of individuals with DS (Pinter et, 2001) report of smaller overall brain volumes, with disproportionately smaller cerebellar volumes and relatively larger subcortical gray matter volumes Also noted is relative preservation of parietal lobe gray and temporal lobe white matter relative to control subjects. No abnormalities in patterns of brain asymmetry have been noted in Down's syndrome subjects

21. Recall what the characteristic dyslexia profile is like: • Deficits in phonological awareness tasks • Deficits in short term auditory memory • Correlations with rapid object naming • Correlations with vocabulary size Children with a • Correlations with syntax and morphology historyof SLI • Peripheral vision problems?? • Problems in processing temporally sequenced information??

22. If reading achievements and reading difficulties in these populations draw upon similar language skills as does reading in the normal population, we should expect – 1. Children with WS to acquire reading relatively easily since their language skills are preserved and their auditory short term memory for words is at age level 2. Children with DS to acquire reading with great difficulty, if at all, since their language skills are poor as is their auditory short term memory for verbal material 3. IQ levels within the groups should not correlate with word reading

23. We studied word reading and reading related skills in : 1. English speaking adolescents and young adults in the US, n=20 (Levy, Smith & Tager-Flusberg, 2003) 2. Hebrew speaking adolescents and young adults with WS in Israel, n=17 (Levy & Antebi, 2004) 3. Hebrew speaking adolescents and young adults with DS, in Israel, n=17 (Levy & Bieser, in preparation)

24. Participants were beyond the learning phase and were considered by their educators as having reached the highest reading level that they were capable of Individuals who did not recognize the letters of the alphabet were not included in the study Individuals older than 22 years old were not included in the studies in order to maintain some uniformity in the educational practices

25. Since our interest was on word decoding - the focus of the study was on reading novel words Participants were tested on familiar word reading, rhyme, phonological awareness tasks, rapid object naming, vocabulary and syntax We used normative tests whenever possible – The K-BIT, CTOPP, Woodcock-Johnson and the PPVT for English, and the Wechsler, Nizan and BNT for Hebrew Experimental tasks were used for rhyme detection and for syntax

26. Summary of findings in study 1(Levy, Smith, Tager-Flusberg, 2003(English speaking adolescents with WSn=20; age=16.4 (12.8-20.4) • Three participants (15%) could not read even a single novel word, i.e. they were “non-readers” • Non-readers failed the rhyming task, whereas the 17 readers were at ceiling on rhyme detection • Rapid naming was poor in the group as a whole • The best predictor of word decoding was performance on the non verbal part of K-BIT

27. Correlations between word decoding (WordAtt), IQ and reading-related skills in English speaking readers with WS (n=17)

28. Correlations between word decoding (WordAtt), IQ and reading-related skills in English speaking readers with WS with K-BIT def. held constant (n=17)

29. Reading and related skills in English speaking adolescents with WS by IQ range (n=20)

30. Summary of findings in study 2:(Levy and Antebi, 2004)Hebrew speaking adolescents with WS N=17; mean age 14;4 (11;3-22) • Non-readers were twice as many as in the English speaking group – 6 individuals - ~35% • Performance on rhyming among the readers was at ceiling • Performance on rapid naming was poor across the board • The best predictor of word decoding was performance on the Wechsler

31. Some relevant facts about Hebrew orthography Hebrew marks most of its vowels as diacritics over and below the line. For example: יֶלֶד yeled מִגְדָל migdal When diacritics are marked Hebrew has a shallow orthography, i.e. there is a good mapping between letters + diacritics and sounds Hebrew orthography without diacritics is opaque ילד yld מגדל mgdl

32. Children are taught to read with diacritics Word reading is mastered relatively early However, diacritics are gradually dropped from written texts from grade 3 and on and most adult written Hebrew is without diacritics Our task presented novel words with diacritics It is possible that for individuals with WS who experience specific difficulties in visual motor and visual integration tasks, integrating two perceptually disparate systems created a unique difficulty

33. Age, IQ and level of word reading in Hebrew speaking participants with WS

34. Correlations between word reading, rapid naming, vocabulary, phonological awareness and IQ in Hebrew speaking readers with WS (n=11)

35. Word reading and language skills by IQ, in Hebrew speaking adolescents with WS

36. Previous studies of reading in individuals with WS • Several studies have looked at reading in WS – Udwin et al (1987), Howlin et al (1998), Laing et al (2001), Vicari et al (2004) • Similar percentages of non-readers to our English sample were reported • The studies did not focus on word decoding but looked at comprehension as well • There has not been a systematic attempt to correlate word reading with scores on IQ test • Since very young children – 6 yr. olds – were among the participants studied such correlations would not be meaningful

37. Summary of study 3(Levy & Bieser, in press)Hebrew speaking adolescents with DS N=17; mean age 17;06 (13;2 – 20;1) • Four participants ~ 27%, were non-readers, i.e. they could not read a single novel word • Rhyme and rapid object naming did not correlate with word reading • Syntax comprehension and production did not correlate with word reading • Scores on the Wechsler as well as performance on phonological awareness tasks correlated with word reading • Grammaticality judgments correlated with word reading

38. IQ and word reading in Hebrew speaking children with DS

39. Correlations between word reading, rhyme, phonological awareness tasks and IQ in Hebrew speaking participants with Down syndrome

40. Correlation between word decoding, syntax comprehension and production and grammaticality judgments in Hebrew speaking adolescents with Down syndrome

42. Previous studies of reading in individuals with DS • Not many studied have looked at word reading in this population • There have been reports of hyper-lexic children with Down syndrome • A recent study (Laws & Gunn, 2002) reports of a higher percent of non-readers than we found. However, age and IQ have not been controlled for • Their follow-up study suggests that the higher the IQ, the more likely the children are to acquire word decoding

43. Summary of the findings • Contrary to expectations, reading level in individuals with WS was similar to reading level of IQ matched individuals with DS • Rapid naming and vocabulary did not predict word decoding in either group • Syntax did not predict word decoding in individuals with DS • Phonological awareness and grammaticality judgments were correlated with word decoding • Performance on IQ tests correlated with word decoding

44. Hebrew speaking individuals with WS DS

46. The aim of this research was to find out whether adolescents with either WS or DS who speak Hebrew or English are, in fact, dyslexic We asked whether the pattern of strengths and weaknesses in word reading seen in the groups studied was the same as the familiar dyslexia cluster Based on our findings the answer is NO!

47. We make the following claims: • Poor reading in WS and in DS does not arise from poor language skills. The problem lies with the need to engage in explicit learning of word decoding • Performance on IQ tests is a good predictor of a person’s potential performance when explicit learning is called for (phonological awareness tasks, grammaticality judgments) • The prediction is that in children with cognitive disabilities other skills requiring explicit learning will show a similar dependency on IQ

48. We offer to restore the intuition behind the discrepancy definition of dyslexiasince we think that reading disorders in syndromic populations is unlike dyslexia The reading disorder seen in WS and in DS differ from dyslexia in that they are not language related and they concern difficulties with explicit learning of which reading is but one domain Such difficulties will be seen in people with intellectual disabilities across syndromes and across knowledge areas

49. Understanding probability in WS Step I: Step II: Experimenter throws Which dreidel the dice would you like to spin?

50. The experiment was run with the Israeli group of WS in two different versions: a roulette version and a dreidel version After making their choices and trying their luck, children were asked to explain why they picked one dreidel or the other