926 3-4 year-old children were surveyed in 2020-2022 using a wide array of potential markers (436 markers were assessed in 926 children, of those 383 were with ASD, 200 with developmental delay, 343 belonged to a norm group) in order to identify the most reliable autism markers and develop a screening scale for autism risk.The main result of the study was the elaboration of Autism Scale, based on 40 items representing 4 vectors of its manifestation to differentiate between ASD, developmental delay and typically developing 3-4-year-olds: "Emotional Impairment", "Sensory Impairment", "Communication Disorders" and "Hyperactivity/Restlessness". The scale has a predictive accuracy of 88.91% (sensitivity 92.1%, specificity 87.2%). Multigroup confirmatory factor analysis of structural and dimensional equivalence confirmed the 4-vector structure of ASD for a sample of children with ASD; its structural and dimensional invariance with respect to children with ASD differing in gender and age was confirmed. However for children without ASD its equivalence was not confirmed.

In the next stage of the study, the aim was to identify autism vectors that are specific to 3-4-year-old children with ASD, based on survey data collected on 383 children with ASD. As a result, a 7-factor structure was identified, ranging from 9 to 14 items in each factor (78 items in total). Each factor was clearly interpreted by its component items: 1) "Insistence on sameness"; 2) "Emotional disinhibition"; 3) "Detachment"; 4) "Speech comprehension"; 5) " Hyperactivity/Restlesness"; 6) "Echolalia"; 7) "Sensory disintegration". Currently, the next stage of research is underway to analyze the factor structure of ASD in 2-3-year-old and in 5-7 year-old, with the development of sufficient screening scales to assess risks of ASD.The research is supported by a grant from the Russian Science Foundation # 23-18-00155.