In 2020 – 2022 we conducted a survey of 926 children (383 with ASD, 200 with DD, 343 Norm group) in order to elaborate a screening scale for the expert diagnosis of ASD in 3-4-year-olds. For the examination we used an online questionnaire developed by us to identify 436 possible symptoms of autism. The questions were answered by specialists involved in correctional work with children. The main result of the study was elaboration of Autism Scale based on 40 autism symptoms (points) representing 4 vectors of its manifestation: 1) difficulties in establishing emotional contact, expressing one's emotions and decoding the emotions of others in the context of social interaction; 2) sensory disintegration; 3) difficulties in verbal and non-verbal communication and social skills; 4) hyperactivity, including excessive movements, motor disinhibition and restless behavior. The Scale has a prediction accuracy of 88.91% (sensitivity 92.1%, specificity 87.2%) (Nasledov, Miroshnikov, Tkacheva, Miroshnik, & Semeta, 2021). The structural and measurement invariance of this model was confirmed for boys and girls, 3- and 4-year-olds (Nasledov et al., 2021). In 2023 233 5-6-year-olds with ASD were examined using an online questionnaire including 40 points of the mentioned above Scale, in order to study the suitability of the developed Scale for diagnosing children of this age and identification of possible age-related changes. A multigroup confirmatory factor analysis showed that the Autism Scale, the 4-factor version of which was developed for 3-4-year-old children, retained structural and measurement equivalence for 5-6-year-olds. The accuracy of differentiation of the group of children with ASD from other children for this age remained high (85.8%), only slightly lower than for 3-4-year-olds. Apparently, this is due to the fact that the identified 4 factors (vectors) of ASD symptoms are the areas in which children with ASD differ the most from other children, and are least susceptible to age-related changes. Further, the values of the factors were calculated for children as the average values of the points included in each factor. A multidimensional ANOVA was used to study age shifts: Gender factor (1st, 2nd), Age factor (1 – 3-4-year-olds, 2 – 5-6-year-olds), dependent variables – 4 calculated factors. Multidimensional criteria revealed statistically significant main effects of the factors Gender and Age, the effect of the interaction of these factors was not statistically significant. According to one-dimensional criteria, girls, regardless of age, have statistically significantly stronger symptoms of Communication disorders than boys. Regardless of gender, the influence of age according to one-dimensional criteria was revealed in relation to Communication disorders and Sensory disorders. These symptoms decrease with age, apparently under the influence of corrective interventions. Regarding Emotional disorders and Hyperactivity/Disinhibition age differences are far from statistically significant. These symptoms remain at a consistently high level with age, apparently as more resistant to corrective interventions.