Delayed speech and language development is one of the main diagnostic criteria for autism spectrum disorders (ASD) and is found almost in all children with ASD. Language development in children with ASD may differ from the norm both quantitatively (delayed speech development, reduced vocabulary, scarcity of speech and limitation in its use) and qualitatively (echolalias, violation of speech grammatical structure, difficulties in the communicative use of speech). Studying different aspects of language development in ASD is very important as it provides opportunities for finer diagnostics, as well as for targeted correction of communication disorders.

The study included 34 primary-school-aged children, who were diagnosed ASD using ADOS-2, diagnostic groups included “autism” (24 children) and “autism spectrum” (8 children). Speech development was assessed using the “Korablik” test on 9 parameters: distinguishing sounds; understanding and generating nouns, verbs and syntax; text understanding; sentences repetition. Kaufman test battery (KABC-II) and the Wechsler test (WISC-III) were used to assess non-verbal intelligence. The sample was divided into two subgroups according to an educational program recommended by PMPC (Psychological, Medical and Pedagogical Commission). Group 1 included 15 children, attending program 8.1, which is recommended for children with ASD who reach developmental milestones before starting study. Group 2 included 19 children attending program 8.2, which is recommended for children with ASD who do not reach developmental milestones before starting study.

In general, all children were the best successful in understanding and generating nouns, understanding verbs, and the least successful in understanding text and searching for sound in the word. Comparing subgroups using Mann-Whitney test revealed significant differences in all measured speech parameters, except for word repetition and noun generation. Group 2 demonstrated uneven results for separate subtests - minimum scores in some subtests coexisted with maximum in others. The group also showed uneven scores distribution inside the subtests, for example, half of the children did not cope with the task to determine a sound in a word, while the rest successfully completed at least 83% of the task. A significant positive correlation between all speech subtests was found in the group. Correlation analysis for parameters of speech development, severity of autistic manifestations and non-verbal intelligence revealed a significant direct relationship between the total scores of impressive and expressive speech and IQ and an inverse relationship with the severity of autistic manifestations and disorders of social and communicative behavior. No relationships like described above were found for group 1.

Obtained results indicate variability of reasons for delayed development of various language aspects in children with ASD.