Effects in language development of young children with language delay during early intervention

In the Netherlands, early language intervention is offered to young children with Language Delay (LD). The intervention combines groupwise language intervention, individual speech and language therapy and parent-implemented language intervention. This study tests the hypothesis that children with LD show progress in their receptive and expressive language during intervention. Differences in language progress between age groups (< 36 months and ≥ 36 months at intervention start) were expected in favour of the younger group, which might be due to an earlier intervention start, a longer treatment duration or the potential presence of late talkers.

The study included 183 children with LD (45 children < 3 years of age at intervention start; mean age 32 months, 138 children ≥ 3 years; mean age 40 months). Receptive and expressive language was assessed with norm-referenced tests at intervention start and ending using Routine Outcome Monitoring. A repeated measures MANOVA was carried out to examine language progress and to compare the age groups on receptive syntax, receptive vocabulary, expressive syntax and expressive vocabulary. The Reliable Change Index was used to study individual progress.

On average, children in both age groups showed significant improvement in all four language domains. The younger children showed more language progress than the older children in all four domains. When examining individual progress, most of the children displayed reliable improvement for expressive vocabulary. Most children developed in the same pace as their typically developing peers for receptive syntax, receptive vocabulary, and expressive syntax.

Children stabilized or even improved language proficiency during the intervention, indicating that the language gap between these children and typically developing children did not widen further. Younger children displayed more language progress than older children in all four domains, but it is unclear what might explain this difference.