At the present stage of development of medicine and society, there is no doubt that early detection and treatment of nervous system diseases accompanied by impaired cognitive functions is one of the main tasks of clinical neurology. The prevalence of cognitive impairment (CI) is so high that today we can say that it exceeds the particular "epidemic" threshold, when the problem causes not only medical, but also a serious socioeconomic burden. Currently, studies of the problem of CI have shifted focus to the non-dementia stages of diseases. In recent years, it has become possible to make early nosological diagnosis of CI even before the development of dementia, which is associated with the development and introduction of in vivo laboratory and neuroimaging markers of Alzheimer's, neurodegenerative, and vascular processes. The paper discusses the existing classification and diagnostic criteria for non-dementia stages of CI. It proposes a new category, such as the initial signs of cognitive impairment, and presents diagnostic criteria. The author considers the importance of an integrated approach to diagnosing CI with the aim of early identification of the nosological entity of the syndrome. He presents a critical review of existing approaches to preventing and treating the non-dementia stages of CI.