Cognitive decline is one of the main manifestations of brain damage especially in the elderly. In some cases, cognitive dysfunction stayed within normal aging and do not lead to social dis-adaptation, while in other cases severe cognitive impairment develops when daily activity and domestic independence is affected. However, these disturbances are preceded by prolonged intermediate stage, when cognitive deficit do not reach the degree of dementia, but already do not match normal aging. Initial terms (for example benign senescent forgetfulness) were interpreted as aging phenomena. Later this state named as mild cognitive impairment (MCI) is considered as prodromal phase of demented disease. Up to date studies allow us consider MCI as an integral part of the complex structure of overlapping syndromes (“pre-cognitive impairment”), the allocation of which have not only theoretical, but also pragmatic meaning, allow us, on the one hand, to plan clinical trials series with various therapeutic targets, and, on the other hand, to form rational approach to the modern management of patients with MCI and pre-MCI in clinical practice.