Syntactic development in children with intellectual disabilities – using structured assessment of syntax

BACKGROUND: Children with intellectual disabilities (IDs) have a severe delay in syntactic development compared with other language abilities. This study investigated conditions of syntactic development in native Japanese-speaking children with ID. METHODS: Children with ID [N = 51; 18 autism spectrum disorders (ASD), 18 Down syndrome (DS) and 15 ID without ASD and DS] were compared with typically developing children (N = 78) with the same mental age (MA). The development of syntax in spoken language was examined by receptive and production tasks. RESULTS: The development of syntax in children with ID was significantly delayed than in typically developing children with the same MA. However, when reaching the MA of 7-9, syntax abilities started to develop remarkably. Moreover, children with ASD had significant difficulties in acquiring passive voice, whereas children with DS showed a significant delay in syntactic development. CONCLUSIONS: The development of syntax in children with ID might be affected by MA and the type of disability. Moreover, it is necessary to exceed an MA of 7-9 years for children with ID to develop syntax abilities.