Reading comprehension in children with Down syndrome.

Two studies aimed to investigate the reading comprehension abilities of 14 readers with Down syndrome aged 6 years 8 months to 13 years relative to those of typically developing children matched on word reading ability, and to investigate how these abilities were associated with reading accuracy, listening comprehension, phonological awareness and vocabulary knowledge. Study 1 confirmed significantly poorer passage-reading comprehension than the typically developing group. In an experimental task, readers with Down syndrome understood fewer written sentences than the typical group and, contrary to prediction, received no advantage from printed sentences compared to spoken sentences, despite the lower memory load. Reading comprehension was associated with listening comprehension, word reading and phonological awareness in DS. Vocabulary knowledge was also associated with reading comprehension, mediated by word reading and nonverbal cognitive abilities. Study 2 investigated the longitudinal relationships between reading and language measures in the readers with DS over around 22 months. Time 1 listening comprehension and phonological awareness predicted Time 2 reading comprehension but there was no evidence that reading or reading comprehension predicted Time 2 language scores or phonological awareness, and no evidence that readers had acquired greater depth of vocabulary.

Receptive vocabulary and semantic knowledge in children with SLI and children with Down syndrome.

Receptive vocabulary and associated semantic knowledge were compared within and between groups of children with specific language impairment (SLI), children with Down syndrome (DS), and typically developing children. To overcome the potential confounding effects of speech or language difficulties on verbal tests of semantic knowledge, a novel task was devised based on picture-based semantic association tests used to assess adult patients with semantic dementia. Receptive vocabulary, measured by word-picture matching, of children with SLI was weak relative to chronological age and to nonverbal mental age but their semantic knowledge, probed across the same lexical items, did not differ significantly from that of vocabulary-matched typically developing children. By contrast, although receptive vocabulary of children with DS was a relative strength compared to nonverbal cognitive abilities (p < .0001), DS was associated with a significant deficit in semantic knowledge (p < .0001) indicative of dissociation between word-picture matching vocabulary and depth of semantic knowledge. Overall, these data challenge the integrity of semantic-conceptual development in DS and imply that contemporary theories of semantic cognition should also seek to incorporate evidence from atypical conceptual development.

Early hearing loss and language abilities in children with Down syndrome.

BACKGROUND: Although many children with Down syndrome experience hearing loss, there has been little research to investigate its impact on speech and language development. Studies that have investigated the association give inconsistent results. These have often been based on samples where children with the most severe hearing impairments have been excluded and so results do not generalize to the wider population with Down syndrome. Also, measuring children's hearing at the time of a language assessment does not take into account the fluctuating nature of hearing loss in children with Down syndrome or possible effects of losses in their early years. AIMS: To investigate the impact of early hearing loss on language outcomes for children with Down syndrome. METHODS & PROCEDURES: Retrospective audiology clinic records and parent report for 41 children were used to categorize them as either having had hearing difficulties from 2 to 4 years or more normal hearing. Differences between the groups on measures of language expression and comprehension, receptive vocabulary, a narrative task and speech accuracy were investigated. OUTCOMES & RESULTS: After accounting for the contributions of chronological age and nonverbal mental age to children's scores, there were significant differences between the groups on all measures. CONCLUSIONS & IMPLICATIONS: Early hearing loss has a significant impact on the speech and language development of children with Down syndrome. Results suggest that speech and language therapy should be provided when children are found to have ongoing hearing difficulties and that joint audiology and speech and language therapy clinics could be considered for preschool children.

Do children with Williams syndrome really have good vocabulary knowledge? Methods for comparing cognitive and linguistic abilities in developmental disorders.

The comparison of cognitive and linguistic skills in individuals with developmental disorders is fraught with methodological and psychometric difficulties. In this paper, we illustrate some of these issues by comparing the receptive vocabulary knowledge and non-verbal reasoning abilities of 41 children with Williams syndrome, a genetic disorder in which language abilities are often claimed to be relatively strong. Data from this group were compared with data from typically developing children, children with Down syndrome, and children with non-specific learning difficulties using a number of approaches including comparison of age-equivalent scores, matching, analysis of covariance, and regression-based standardization. Across these analyses children with Williams syndrome consistently demonstrated relatively good receptive vocabulary knowledge, although this effect appeared strongest in the oldest children.

High heritability of speech and language impairments in 6-year-old twins demonstrated using parent and teacher report.

Previous twin studies have demonstrated high heritability of specific language impairment (SLI) when the diagnosis is based on psychometric testing. The current study measured the effectiveness of parent and teacher ratings of communication skills in identifying heritable language impairment. The Children's Communication Checklist was completed by parents and teachers of 6-year-old twins recruited from a general population sample. One hundred and thirty twin pairs (65 MZ) were selected because at least one twin had low language skills at 4 years of age; a further 66 pairs (37 MZ) were a low risk group with no indication of language difficulties at 4 years. Internal consistency, inter-rater reliability, and validity in identifying language impairment were assessed for all CCC scales. CCC scales, especially those assessing structural language skills, were highly effective in identifying cases of language impairment, but agreement between parent and teacher ratings was modest. Genetic analysis revealed negligible environmental influence and substantial genetic influence on most scales. A rater-specific effects model was fit to the data to assess how far parents and teachers assess a common genetic factor on the CCC. Ratings of parents and teachers were influenced to some extent by the same child characteristics, but rater-specific effects were also evident, especially on scales measuring pragmatic aspects of communication. This study shows that there are strong genetic influences on both structural and pragmatic language impairments in children, and these can be detected using a simple checklist completed by parents or teachers.

A case of exceptional reading accuracy in a child with Down syndrome: Underlying skills and the relation to reading comprehension.

We report on a case of a girl with Down syndrome (DS), K.S., whose reading accuracy is exceptional. This ability is associated with robust phonological skills and relative strengths in visual and verbal short-term memory, articulation, and speech fluency. Although her reading comprehension is age appropriate when it comes to the retention of literal information, K.S. has some difficulties in using knowledge-based inferences in reading comprehension. Reading comprehension in that sense is at a level commensurate with her oral language skills. Her reading performance parallels that of children with reading comprehension difficulties who do not have DS. This reading profile is in contrast with claims that individuals with DS mainly use sight-word strategies in reading and shows that the phonological pathway can be highly proficient in a child with DS. However, even in a case such as K.S. where reading accuracy is good, functional literacy is constrained by limited comprehension skills.

Contributions of phonological memory, language comprehension and hearing to the expressive language of adolescents and young adults with Down syndrome.

BACKGROUND: Expressive language constitutes a major challenge to the development of individuals with Down syndrome. This paper investigates the relationships between expressive language abilities, language comprehension and the deficits in verbal short-term memory and hearing which are also associated with the syndrome. METHODS: Tests of nonverbal ability, expressive language, verbal short-term memory, visuo-spatial memory, language comprehension and hearing were administered. RESULTS: Phonological memory, measured by nonword repetition, was significantly correlated with expressive language abilities measured by MLU and sentence recall. Adjusting for word repetition skills did not reduce this correlation, suggesting that the relationship did not depend on the fact that both tests required spoken output. Hearing did not contribute significantly to expressive language scores of participants who provided an intelligible narrative. However, level of hearing loss as well as other language and memory measures did differentiate these participants from those who were unable to produce an intelligible narrative. CONCLUSION: Phonological memory was closely associated with the expressive language abilities of individuals with Down syndrome. Hearing loss appeared to be less closely related except that individuals with uncorrected mild to moderate hearing loss had difficulty with the narrative task. Further research is necessary to establish the nature of these relationships.

Phonological memory as a predictor of language comprehension in Down syndrome: a five-year follow-up study.

BACKGROUND: This study reports the language and memory progress over five years of 30 adolescents and young adults with Down syndrome, and investigates the relationship of earlier phonological memory abilities to later language development. METHODS: Tests of nonverbal ability, receptive vocabulary, grammar comprehension, digit span and nonword repetition were administered at two points in time. RESULTS: For the sample as a whole, there were significant gains in nonverbal ability, receptive vocabulary and grammar comprehension, but no increases in phonological memory measured by nonword repetition or digit span. However, there were considerable individual differences in progress which, in part, were related to chronological age. Phonological memory improved in many younger participants but there were signs of decline in some older ones. Partial correlations between earlier nonword repetition scores and later language scores, controlling for nonverbal ability and earlier language scores, indicated a significant role for phonological memory in the acquisition of vocabulary knowledge. There was similar evidence of a role for phonological memory in grammar comprehension, but only for younger participants. Earlier receptive vocabulary also predicted later nonword repetition scores, particularly for participants with higher levels of vocabulary knowledge. CONCLUSION: Relationships among the processes involved in language and memory development in Down syndrome may be similar to those established for typical development.

Pragmatic language impairment and social deficits in Williams syndrome: a comparison with Down's syndrome and specific language impairment.

BACKGROUND: The social communication strength of individuals with Williams syndrome described by some researchers contrasts with the picture of social difficulties painted by others. AIMS: To study the pragmatic aspects of language, social relationships and unusual interests in a group of children and adults with Williams syndrome, and to compare them with a group of children and adults with Down's syndrome, children with specific language impairment, and a group of typically developing children. METHODS & PROCEDURES: Parents or teachers completed the Children's Communication Checklist or a modified version of it with wording appropriate for adults. Study groups consisted of 19 children and young adults with Williams syndrome, 24 with Down's syndrome, 17 children with specific language impairment and 32 typically developing children. OUTCOMES & RESULTS: Checklist ratings for the group with Williams syndrome indicated significant levels of pragmatic language impairment, and difficulties with social relationships. Together with evidence of unusual or restricted interests, the results suggested deficits across all three domains covered by the checklist. CONCLUSIONS: Despite earlier reports that emphasize a strong social interest and empathy, this study suggests that individuals with Williams syndrome have pragmatic language impairments, poor social relationships and restricted interests. Far from representing the polar opposite of autism, as suggested by some researchers, Williams syndrome would seem to share many of the characteristics of autistic disorder.

Verbal deficits in Down's syndrome and specific language impairment: a comparison.

BACKGROUND: Down's syndrome is a chromosome disorder characterized by a range of physical and psychological conditions, including language impairment. The severity of impairment is variable, and some components of the language system appear to be more affected than others. This description could also be applied to typically developing children diagnosed with specific language impairment. AIMS: To compare findings from the largely separate research literatures on these conditions, and to address the questions about whether the language pathology associated with Down's syndrome could be the same as that described as specific language impairment in typical development, and whether the two conditions could have similar causes. MAIN CONTRIBUTION: Research studies suggest similar patterns of language impairment in the two populations, and some similarities in underlying processing deficits. CONCLUSIONS: Future research should consider whether similarities in the language behaviours associated with Down's syndrome and specific language impairment could be related to similarities at other levels of analysis, including neurological development and genetics.

A comparison of language abilities in adolescents with Down syndrome and children with specific language impairment.

This article compared the language profiles of adolescents with Down syndrome (DS) and children with specific language impairment matched for nonverbal cognitive ability, and investigated whether similar relationships could be established between language measures and other capacities in both groups. Language profiles were very similar: Expressive language was more affected than language comprehension, and grammar was more affected than vocabulary in both domains. Both groups were impaired on tests of grammatical morphology and phonological memory. There were some differences between the groups, but these could be attributed to other features of development of people with DS.

Working memory in children and adolescents with Down syndrome: evidence from a colour memory experiment.

BACKGROUND: This paper reports information on the visual and verbal short-term memory of individuals with Down syndrome. METHODS: Colour memory in 16 children and adolescents with Down syndrome was compared with that of 16 typically developing children matched for receptive vocabulary. It was suggested that focal colours should be remembered more successfully than non-focal colours on the basis that the former could be remembered using a verbal recoding strategy. However, children with Down syndrome, for whom a deficit in verbal short-term memory makes the use of such a strategy unlikely, should remember focal and non-focal colours equally well. More importantly, if individuals with Down syndrome have more developed visual memory abilities than control children, they should outperform them in recognising non-focal colours. RESULTS: Although the group with Down syndrome demonstrated significantly better Corsi blocks performance than controls, and displayed similar levels of colour knowledge, no advantage for colour memory was found. Non-focal colours were remembered by individuals with Down syndrome as successfully as focal colours but there was no indication of a visual memory advantage over controls. Focal colours were remembered significantly more successfully than non-focal colours by the typically developing children. CONCLUSION: Their focal colour memory was significantly related to digit span, but only Corsi span was related to focal colour memory in the group with Down syndrome.