Alzheimer's disease (AD) is the most common neurodegenerative disease and the most common cause of dementia. In daily practice, AD is often diagnosed late, while the early stages of the disease are overlooked or mistaken for cerebrovascular pathology. However, the efficacy of existing and newly developed (disease-modifying) AD therapies is the greatest in the early stages of the disease. An accurate diagnosis of AD is possible when biological markers of the main pathological process (cerebral amyloidosis, tauopathy) are detected using positron emission tomography or neurochemical examination of cerebrospinal fluid, which are gradually being introduced into practice in Russia. The experts discussed the clinical aspects of the use of biological markers, obtained in the leading specialized centers of our country for the diagnosis and treatment of cognitive impairment (CI). First and foremost, biomarker testing is indicated in patients with mild CI and mild dementia possibly associated with AD, so that disease-modifying (pathogenetic) therapy can be initiated as early as possible upon on its availability (currently, drugs for anti-amyloid disease-modifying therapy are not registered in the Russian Federation). Patients with a non-classical (non-amnestic) or atypical AD phenotype are another group of patients in whom it is also advisable to analyze biomarkers for differential diagnostic purposes.