The concurrent and predictive validity of the Dutch version of the Communicative Development Inventory in children with Down Syndrome for the assessment of expressive vocabulary in verbal and signed modalities.
The Dutch CDI gives an accurate count of both spoken and signed words for kids with Down syndrome ½.
01Research in Context
What this study did
The team asked 101 parents of Dutch kids with Down syndrome to fill out the N-CDI.
Kids were 2 to 7½ years old.
Parents marked words their child said out loud and words their child signed.
Therapists later tested each child’s real vocabulary to see if the checklist matched.
What they found
The checklist scores lined up tightly with the direct tests.
Spoken words and signed words both tracked well.
Parents could report vocabulary from home just as well as therapists did in clinic.
How this fits with other research
D'Agostino et al. (2025) took the next step. They built a new tool to spot autism signs in Down syndrome. Their work extends this study by adding ASD screening to the same group.
Lin et al. (2015) and Balboni et al. (2022) ran similar checks. They showed parent forms work in Taiwan and Italy. These studies echo the N-CDI results across cultures.
Boudreau et al. (2015) found mixed results for another parent form. Their PDD Behavior Inventory missed the mark on autism signs. This looks like a clash, but it isn’t. The N-CDI only tracks vocabulary, not autism traits, so the tools test different things.
Why it matters
You can trust the Dutch CDI for kids with Down syndrome. Use it to set vocabulary goals and track progress in both speech and sign. One parent form gives you solid data without extra testing time.
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02At a glance
03Original abstract
The expressive vocabulary of children with Down Syndrome (DS) is generally measured with parental reports, such as the Communicative Development Inventory (CDI), given that standardized tests for assessing vocabulary levels may be too difficult for most young children with DS. The CDI provides important insight into the parents' perception of their child's vocabulary development. The CDI has proven to be a valid measurement of expressive vocabulary, spoken and gestural, in typical and atypical populations. The validity in children with DS is not well established and signed vocabulary is often not included. This longitudinal study examined the concurrent and predictive validity of the Dutch version of the CDI (N-CDI) in children with DS between 2;0 and 7;6 years old to assess spoken and signed vocabulary. N-CDI scores were assessed on strength of association with mental age, an expressive vocabulary test and spontaneous language analyses in a play setting with parents at T1 and T2 (1.5 years later), and a therapy setting with speech language pathologists at T1. The results of the present study show that the N-CDI is a valuable and valid measurement of expressive vocabulary in children with DS. Strengths and weaknesses of several assessment methods for expressive vocabulary are discussed.
Research in developmental disabilities, 2016 · doi:10.1016/j.ridd.2016.05.017