Is expressive language delayed relative to receptive language among infants with Down syndrome?

This longitudinal project was designed to chart the progress of receptive and expressive language in infants with Down syndrome and to see if young children with Down syndrome showed a delay is saying first words compared to typically developing children.

It has been suggested that children with Down syndrome have a specific delay in starting to say first words; that is, they may not start to talk even when they understand as many words as typically developing children do when they begin to talk. This question has implications for understanding the reasons for their ongoing speech and language delays and for developing interventions.

For this study, 30 children with Down syndrome and 35 typically developing children were recruited. The children with Down syndrome ranged in age from 17 months to 23 months at the start of the study with a group mean age was 19.7 months. The typically developing children ranged in age from 9 to 11 months at the start, with a group mean of 10.4 months. In both groups they were just starting to say their first words. Following the first assessments, in order to match the two groups on NVMA at the start of the study, the two groups were reduced to 26 TD infants and 23 with Down syndrome.

A range of measures of non-verbal mental age (NVMA) and expressive and receptive language were collected three times, at the start of the study and then at 6 months and 12 months from the first assessments.

The main finding show that the TD infants were making faster progress than the infants with Down syndrome on both the receptive and expressive language measures over the 12-month period, particularly in the last 6 months. A second comparison was made when the two groups had made the same progress on the non-verbal mental age measure so could be matched again on this. The children with Down syndrome reached the same NVMA after 12 months, as the TD infants reached after 6 months. When the two groups were matched for NVMA progress, there were no significant differences in their expressive language development but the infants with Down syndrome were now ahead of the TD infants on receptive language.

In summary, the early expressive language of the infants with Down syndrome was as expected for their non-verbal mental ability but their receptive language was advanced for their mental age possibly because they were older than the TD children when at the same level on non-verbal ability and had had more time to learn vocabulary. This does suggest that their expressive language was delayed relative to their receptive language even if it was at the level expected for their cognitive ability as measured by NVMA. The reasons for this need and its implications for interventions more investigation.

Publication

Mason-Apps, E. , Stojanovik, V. , Houston-Price, C. , Seager, E. , Buckley, S. (2020) Do infants with Down syndrome show an early receptive language advantage? Journal of Speech, Language and Hearing Research, 63 (2). pp. 585-598. https://doi.org/10.1044/2019_JSLHR-19-00157

Funding

• Economic and Social Research Council
• Down Syndrome Education International