Word type and modality in the emerging expressive vocabularies of preschool children with Down syndrome.

BACKGROUND: Previous studies have explored the size and word type composition (nouns, predicates, etc.) of expressive vocabularies of preschool children with Down syndrome, both spoken and signed. Separately, overall preferences for modality of expression have also been explored. AIMS: To extend previous findings by describing the relationships between expressive vocabulary size and both word type and modality of expression in the preschool period including changes to modality preference over time. METHODS & PROCEDURES: Mothers of 35 children with Down syndrome, aged 36-66 months and attending the same early intervention programme, completed a version - with both spoken word and sign options - of the New Zealand MacArthur-Bates Communicative Development Inventory (CDI): Words and Sentences. Most mothers completed the CDI on multiple occasions across the duration of the study. Completions (n = 114) were analysed cross-sectionally and longitudinally in terms of (1) word type relative to vocabulary size, (2) modality of expression relative to word type and vocabulary size, and (3) individual trajectories in vocabulary size and modality of expression. OUTCOMES & RESULTS: (1) Word type relative to vocabulary size was similar to previous studies with a greater proportion of the SOCIAL words being present in the children's vocabularies throughout, followed by NOUNS, PREDICATES and CLOSED class words, with proportions converging as vocabulary sizes increase. (2) An initial spoken word preference for SOCIAL and CLOSED class words and sign preference for NOUNS and PREDICATES was found, with more spoken words in larger vocabularies overall. (3) Individual trajectories were highly variable and also revealed temporary points of regression in overall expressive vocabulary size in some children. Children who shifted from reliance on sign to predominantly spoken word expression did so at different ages and at different vocabulary sizes. At school entry, while most of the children used both modalities, some children continued to rely on sign for most vocabulary items whereas others used only spoken words. CONCLUSIONS & IMPLICATIONS: An appreciation of both the general trends and potential for individual variation in vocabulary structure, modality of expression and change over time will better position clinicians and education specialists to provide individually tailored support to both preschool and school-aged children with Down syndrome. WHAT THIS STUDY ADDS: What is already known on this subject Preschool children with Down syndrome have been shown to demonstrate developmental patterns in overall conceptual vocabulary size and word type development broadly similar to typical development. The use of signed vocabulary has also been explored, but independently from word type development and with less attention to individual trajectories in either vocabulary size development or modality preferences throughout the preschool period than is necessary for clinical use. What this paper adds to existing knowledge This study found interactions between word type and modality of expression in relation to vocabulary size as well as a few temporary vocabulary size regressions similar to those found in much younger typically developing children. An initial spoken word preference for social and closed class words, and sign preference for nouns and predicates, was followed by a general trend towards spoken words for all word types as vocabulary (with some fluctuations) increased over time. Children demonstrated considerable individual variation in size of vocabulary and age at which they pivoted from a signed to a spoken word preference. Moreover, while most children used both modalities at school entry, a few retained a sign-only vocabulary and others had moved fully onto spoken word-only expression. What are the potential or actual clinical implications of this work? An understanding of both the general trends and individual variation in vocabulary structure and modality of expression development will better position clinicians and educational specialists to provide individually tailored support to children with Down syndrome.

The roles of language use and vocabulary size in the emergence of word-combining in children with complex neurodevelopmental disabilities.

Parent report data on 82 preschool children with complex neurodevelopmental disabilities including Down syndrome, dyspraxia, autism, and global developmental delay suggests communicative language use must reach a threshold level before vocabulary size becomes the best predictor of word combining. Using the Language Use Inventory and the MacArthur-Bates CDI (with sign vocabulary option), statistical modelling using regression trees and random forests suggests that, despite high linear correlations between variables, (1) pragmatic ability, particularly children's emerging ability to talk about things, themselves and others is a significantly better predictor of the earliest word combining than vocabulary size; and (2) vocabulary size becomes a better predictor of later word combining, once this pragmatic base has been established.

Parent-mediated interventions for promoting communication and language development in young children with Down syndrome.

BACKGROUND: Communication and language development are areas of particular weakness for young children with Down syndrome. Caregivers' interaction with children influences language development, so many early interventions involve training parents how best to respond to their children and provide appropriate language stimulation. Thus, these interventions are mediated through parents, who in turn are trained and coached in the implementation of interventions by clinicians. As the interventions involve a considerable commitment from clinicians and families, we undertook this review to synthesise the evidence of their effectiveness. OBJECTIVES: To assess the effects of parent-mediated interventions for improving communication and language development in young children with Down syndrome. Other outcomes are parental behaviour and responsivity, parental stress and satisfaction, and children's non-verbal means of communicating, socialisation and behaviour. SEARCH METHODS: In January 2018 we searched CENTRAL, MEDLINE, Embase and 14 other databases. We also searched three trials registers, checked the reference lists of relevant reports identified by the electronic searches, searched the websites of professional organizations, and contacted their staff and other researchers working in the field to identify other relevant published, unpublished and ongoing studies. SELECTION CRITERIA: We included randomised controlled trials (RCTs) and quasi-RCTs that compared parent-mediated interventions designed to improve communication and language versus teaching/treatment as usual (TAU) or no treatment or delayed (wait-listed) treatment, in children with Down syndrome aged between birth and six years. We included studies delivering the parent-mediated intervention in conjunction with a clinician-mediated intervention, as long as the intervention group was the only group to receive the former and both groups received the latter. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methodological procedures for data collection and analysis. MAIN RESULTS: We included three studies involving 45 children aged between 29 months and six years with Down syndrome. Two studies compared parent-mediated interventions versus TAU; the third compared a parent-mediated plus clinician-mediated intervention versus a clinician-mediated intervention alone. Treatment duration varied from 12 weeks to six months. One study provided nine group sessions and four individualised home-based sessions over a 13-week period. Another study provided weekly, individual clinic-based or home-based sessions lasting 1.5 to 2 hours, over a six-month period. The third study provided one 2- to 3-hour group session followed by bi-weekly, individual clinic-based sessions plus once-weekly home-based sessions for 12 weeks. Because of the different study designs and outcome measures used, we were unable to conduct a meta-analysis.We judged all three studies to be at high risk of bias in relation to blinding of participants (not possible due to the nature of the intervention) and blinding of outcome assessors, and at an unclear risk of bias for allocation concealment. We judged one study to be at unclear risk of selection bias, as authors did not report the methods used to generate the random sequence; at high risk of reporting bias, as they did not report on one assessed outcome; and at high risk of detection bias, as the control group had a cointervention and only parents in the intervention group were made aware of the target words for their children. The sample sizes of each included study were very small, meaning that they are unlikely to be representative of the target population.The findings from the three included studies were inconsistent. Two studies found no differences in expressive or receptive language abilities between the groups, whether measured by direct assessment or parent reports. However, they did find that children in the intervention group could use more targeted vocabulary items or utterances with language targets in certain contexts postintervention, compared to those in the control group; this was not maintained 12 months later. The third study found gains for the intervention group on total-language measures immediately postintervention.One study did not find any differences in parental stress scores between the groups at any time point up to 12 months postintervention. All three studies noted differences in most measures of how the parents talked to and interacted with their children postintervention, and in one study most strategies were maintained in the intervention group at 12 months postintervention. No study reported evidence of language attrition following the intervention in either group, while one study found positive outcomes on children's socialisation skills in the intervention group. One study looked at adherence to the treatment through attendance data, finding that mothers in the intervention group attended seven out of nine group sessions and were present for four home visits. No study measured parental use of the strategies outside of the intervention sessions.A grant from the Hospital for Sick Children Foundation (Toronto, Ontario, Canada) funded one study. Another received partial funding from the National Institute of Child Health and Human Development and the Department of Education in the USA. The remaining study did not specify any funding sources.In light of the serious limitations in methodology, and the small number of studies included, we considered the overall quality of the evidence, as assessed by GRADE, to be very low. This means that we have very little confidence in the results, and further research is very likely to have an important impact on our confidence in the estimate of treatment effect. AUTHORS' CONCLUSIONS: There is currently insufficient evidence to determine the effects of parent-mediated interventions for improving the language and communication of children with Down syndrome. We found only three small studies of very low quality. This review highlights the need for well-designed studies, including RCTs, to evaluate the effectiveness of parent-mediated interventions. Trials should use valid, reliable and similar measures of language development, and they should include measures of secondary outcomes more distal to the intervention, such as family well-being. Treatment fidelity, in particular parental dosage of the intervention outside of prescribed sessions, also needs to be documented.

The Home Literacy Environment of Preschool-Age Children with Autism or Down Syndrome.

AIMS: This exploratory study investigated if there were differences in the home literacy environment of preschool children on the autism spectrum and preschool children with Down syndrome to determine if the home literacy environment may potentially be associated with strengths or weaknesses in children's social communication skills. METHODS: A total of 111 parents of preschoolers with identified disabilities completed a home literacy questionnaire. RESULTS: Results indicated that both groups of parents started reading to their children at an early age and owned at least 25 children's books. However, parents of children with Down syndrome read to their child more often, reported higher child interest in reading, and more frequently played rhyming games with their child. No group differences were found in teaching of letter names, although parents of children with autism reported a higher frequency of pointing out signs/words in the environment and reported their children knew more letter names. Group differences were also found in the relationship between parent behaviours, child interest, and children's print-related skills. CONCLUSION: This study highlights the influence both parent behaviours and child interest may have on shared book reading practices of parents with their preschool children with disabilities.

A descriptive study examining phonological awareness and literacy development in children with Down syndrome.

OBJECTIVE AND METHOD: This article describes the profiles of a cohort of 77 New Zealand children with Down syndrome (aged between 5 and 14 years) in areas of particular importance to reading development, namely phonological awareness, word level reading and letter knowledge. Assessment of reading accuracy and comprehension of connected text, as well as further phonological awareness knowledge, was measured in 25 of the more advanced readers in this cohort. RESULTS: The findings showed the expected development with increasing age for letter knowledge, phoneme level awareness and reading tasks. Forty-two percent scored significantly above chance on a phoneme identity task, and most of the participants knew more letter names than letter sounds. Only 17% of the group scored above chance on a rhyme oddity task, and rhyme knowledge was not significantly correlated with age. The majority of the participants could read 1 or more words in isolation and 6.5% demonstrated word level reading at a 7- to 8-year level. Phoneme awareness and letter sound knowledge significantly contributed to word level reading performance. In-depth assessment for the more advanced readers suggested the participants had a comparative strength in reading accuracy compared to reading comprehension and found phonological awareness blending tasks easier than phonological segmentation tasks. Only 1 participant demonstrated strength on a rhyme generation task. CONCLUSION: Discussion focuses on the implications of better understanding the differing language profiles of children with Down syndrome for enhancement of their educational success.

Personal narrative skills of school-aged children with Down syndrome.

BACKGROUND: Personal narratives are descriptions of past events experienced by the speaker and are one of the most commonly found forms of narration in children. The ability to tell personal narratives is considered critical for socio-emotional wellbeing and academic performance. AIMS: This study investigated the personal narrative skills of 25 children with Down syndrome (age 5;11-13;1 years) who attended predominantly mainstream primary schools in New Zealand and were classified as beginning readers. METHODS & PROCEDURES: Personal narrative samples were elicited by the children's speech-language therapists using a standard protocol commonly used with New Zealand children. Children were shown a series of 11 photographs with scripted introductory prompts and were asked if anything like that ever happened to them. Transcribed samples were analysed on measures of mean length of utterance in morphemes (MLU-M), semantics (number of different words; NDW), and personal narrative quality (PNQ). OUTCOMES & RESULTS: Consistent with previous research, results showed wide variability in performance. Although 92% of the children produced at least 50 utterances in response to the prompts, in general MLU-M was very low (mean = 2.67, SD = 1.04). NDW ranged from 19 to 126 (mean = 61.52, SD = 25.39). Regression analyses showed no significant effect for age on MLU-M (p= 0.094), nor on PNQ. There was a significant effect for age on NDW (p= 0.03), with performance improving with age. Analysis of PNQ revealed that only four children (ages 9;11-12;7) were able to relate a personal narrative containing a high point. Correlational analyses indicated significant correlations between PNQ, MLU-M, NDW and performance on a standardized reading test. CONCLUSIONS & IMPLICATIONS: The findings highlight the difficulties children with Down syndrome have in producing personal narratives, despite exposure to a national English curriculum that encourages children to develop and convey 'personal voice'. Clinical implications of these findings will be presented.

Integrated speech and phonological awareness intervention for pre-school children with Down syndrome.

BACKGROUND: Children with Down syndrome experience difficulty with both spoken and written language acquisition, however controlled intervention studies to improve these difficulties are rare and have typically focused on improving one language domain. AIMS: To investigate the effectiveness of an integrated intervention approach on the speech, letter knowledge, and phonological awareness development of ten pre-school children with Down syndrome aged between 4;4 and 5;5. METHODS & PROCEDURES: A multiple single-subject design was used to evaluate treatment effectiveness. Baseline and intervention measures for speech and pre- and post-intervention measures for letter knowledge and phonological awareness were compared. The intervention comprised three components: a parent-implemented home programme; centre-based speech-language therapy sessions, and 'Learning through Computer' sessions with a total intervention time of 20 hours over 18 weeks. Letter knowledge and phonological awareness activities were linked to each child's speech targets. OUTCOMES & RESULTS: Results indicated significant treatment effects on speech measures for all ten participants. Six of the ten participants showed increases on letter knowledge and nine showed increased awareness of initial phonemes in words but responses were not above binomial chance level (that is, 70% correct) for phonological awareness tasks. Individual results are presented and implications for parents and therapists are discussed. CONCLUSIONS AND IMPLICATIONS: The findings of this study suggest an intervention approach that integrates speech, letter knowledge, and phonological awareness targets is effective in remediating speech error patterns at the single-word level in young children with Down syndrome. Phonological awareness and letter knowledge appeared to be stimulated through the intervention, but significant improvement above chance levels on untrained phonological awareness tasks was not evident. Follow-up investigation is necessary to determine longer-term outcomes.