The Expressive Vocabulary Profile in Young Children with Autism Spectrum Disorder

Background: Autism spectrum disorder (ASD) is characterized by qualitatively impairments in social reciprocity and communication, and manifested repetitive and stereotyped behaviors/interests, with onset during early childhood. Parents of ASD often found out something wrong with their children since they didn’t say any or few words around 2-year-old. After being diagnosed with ASD and having interventions, some children can develop their language gradually.   

Objectives: The purpose of this study was to examine the developmental profile of expressive vocabularies in young children with ASD.

Methods: Seventy five children diagnosed with ASD between 24 and 58 months of age (at mean age of 40 months) were recruited and divided into two groups: children with higher nonverbal developmental quotient (NVDQ > 80) and children with lower NVDQ (NVDQ < 80). Mandarin-Chinese Communicative Development Inventory (Taiwan) (MCDI-T) was used to measure the development of expressive vocabularies.

Results: Children with higher NVDQ expressed significantly more vocabularies in all 19 categories in MCDI-T than children with lower NVDQ. However, the two groups had the similar profile of expressive vocabulary composition: expressing the lowest proportion in connecting words, and the order of top three categories were action words, food/drink and people. When the 19 categories were reduced into four categories (social terms, common nouns, predicates and grammatical function words), the two groups also had the similar profile: the highest proportion in common nouns and the lowest proportion in grammatical function words.

Conclusions: This study manifests that NVDQ is highly correlated with the expressive vocabulary size. However, since children with ASD began to expressive vocabularies, they have the same expressive profile, regardless of NVDQ, with typically developing children according to other previous studies. The future studies should include comparison groups, such as children with typical development and developmental delay, to further clarify the expressive vocabulary profile in young children with ASD.