Using the study of cognitive functioning in patients with cardiovascular diseases paper discusses problems of changes in brain activity in patients with somatic diseases related to a main pathology and resulting from surgical treatment. Analysis of the current state of research in this area provided. Based on this analysis, promising areas for further research, such as development of methods for predicting an occurrence and development of cognitive impairment, organization of timely diagnosis of changes in cognitive activity, development of preventive and therapeutic measures, exploring the value of cognitive functioning for treatment adherence. In addition, paper discusses the methodological approaches and main organizational aspects of conducting such studies and indicates the most relevant methods for studying cognitive functioning in a cardiac surgery clinic.