[Autism spectrum disorder-like symptoms in the population with intellectual disability aged 6 to 18 years]

To investigate the incidence of autism spectrum disorder (ASD)-like symptoms in the population with intellectual disability (ID).

The students with ASD or ID, aged 6-18 years, who studied in a special school in Shanghai from January to June, 2017, as well as the typically developing (TD) population of the same age, who studied in a general school in Shanghai during the same period, were enrolled. Social Responsiveness Scale (SRS) was completed by their parents or other guardians, and the ASD-like symptoms were evaluated.

A total of 69 subjects with ASD, 74 subjects with ID and 177 TD subjects were enrolled. The ID group had a significantly higher SRS-positive rate than the TD group (47.3% vs 1.7%; P<0.001) and a significantly lower SRS-positive rate than the ASD group (47.3% vs 87.0%; P<0.001). The total score of SRS was 114±26 in the ASD group, 80±24 in the ID group and 38±19 in the TD group. The ID group had a significantly higher total score of SRS than the TD group (P<0.05), and the score on the subscale of social cognition showed the most significant difference between the two groups (Cohen's d=2.00). There were no significant differences in the total score of SRS and the scores on each subscale of SRS between the mild-to-moderate ID and severe-to-extremely severe ID groups (P>0.05), and there was no significant correlation between SRS score and IQ (P>0.05).

The ID population aged 6-18 years has more ASD-like symptoms than the general population, and ASD screening and intervention should be performed for the ID population as early as possible.