Differential criteria for differentiating oligophrenia and other disorders of mental development: A comparative analysis of international classifications and sources of defectology

The article analyses the problem of differentiating oligophrenia (disorder of intellectual development) from other disorders of mental development. The study is theoretical and analytical: using the comparative-typological method, it examines the ICD-10, ICD-11, DSM-5-TR and AAIDD classifications together with classical sources of special education. As a result, a four-dimensional system of differential criteria is substantiated: totality of the defect, its hierarchical structure, the dynamics of the disorder and learning capacity. On this basis a comparative table and a five-stage differential algorithm are proposed, allowing the delimitation of oligophrenia, delayed psychological development, pedagogical neglect, severe speech disorders, autism spectrum disorders, secondary underdevelopment in sensory impairment and dementia. The practical value lies in reducing diagnostic errors in the work of psychological-medical-pedagogical commissions.