CORRELATION OF MORNING SALIVARY CORTISOL-MELATONIN RATIO WITH QEEG AND DELAYED RECALL IN AGING

Abstract

Melatonin and cortisol are the main hormones of the circadian rhythm, which effect cognitive decline during aging. An imbalance of circadian rhythm hormones serves as an early sign of the progress of age-related disease and brain pathology in aging. The aim of this study was to determine the cortisol-melatonin ratio in relation to brain activity and cognitive function in aging. Sixty-four aging subjects were recruited from the brain healthy project. The morning salivary of all subjects was collected for cortisol and melatonin levels analysis. The brain activity was recorded for 5 minutes in the eyes open condition and seven cognitive functions were assessed by the MoCA. The results were divided into a low ratio group and a high ratio group of cortisol-melatonin ratio. The low ratio group and the high ratio group differed in the delta-beta ratio at the left temporal lope (p < .05), and the delayed recall in the high ratio group was markedly higher than in the low ratio group. Moreover, the cortisol-melatonin ratio was strongly correlated with delayed recall (p < .05), the delta-beta ratio in the left temporal lope (p <.05), the theta alpha ratio in the left temporal lope (p < .05), and right temporal lope (p < .05). We found that a low cortisol-melatonin ratio corresponded to a high delta-beta ratio and a high thetaalpha ratio at the left temporal lobe with a low score of delayed recall function, but a high cortisol-melatonin ratio corresponded to a low delta-beta ratio and a low theta-alpha ratio at the left temporal lobe with a high score of delayed recall. The imbalance of the circadian hormone related to cognitive function and brain activity in aging could serve as a biomarker of age-related diseases.