Background and aim. The relationship between coronary artery disease (CAD) and cognitive impairment (CI) has been established, but the neural mechanisms that underlie this interaction have yet to be identified. CAD patients may exhibit specific manifestations of CI, underscoring the importance of early diagnosis. EEG activity changes are a valuable diagnostic tool to detect brain pathology. The study aimed to investigate the effects of CAD on EEG activity with intact cognitive status and CI.

Methods. The study involved 132 patients with stable coronary artery disease (CAD) aged 45 to 75 years. According to the Montreal Cognitive Assessment Scale (MoCA) results, the patients were divided into two groups: those without CI (no CI), with MoCA scale sum scores ranging from 27 to 30 (n = 37), and those with CI, with MoCA scale sum scores ranging from 20 to 26 (n = 95). The group of practically healthy elderly subjects consisted of 63 individuals aged 43 to 78 years. All patients and healthy participants underwent an EEG study. The mean values of the spectral power density were calculated in the frequency band of 4-30 Hz for the electrode areas symmetrically located in the left and right hemispheres: frontal, central, temporal, parietal, and occipital.

Results. Theta and alpha 2 power values were lower for the healthy elderly group compared to CAD patients, both with and without CI. Furthermore, CAD patients without CI had higher alpha 2 power values than the CI group. The topographic features of the differences in the theta 1 rhythm between the practically healthy elderly group and CAD patients were related to the frontal and temporal areas in patients without CI, as well as to the frontal, temporal, and occipital areas of the brain in the CI group.

Conclusion. The study's data can be used to develop diagnostic tools for identifying cognitive impairment in patients with coronary heart disease at early stages.