Background: Dementia is defined as the gradual worsening of the cognitive functions that remain accompanied by the detectable alterations in the neurophysiological functions. Electroencephalography (EEG) has also become a sensitive, non-invasive instrument to identify cortical slowing whereby the Mini-Mental State Examination (MMSE) is a standardized tool to screen the cognitive status of a person. Determining the connection between changes in EEG oscillations and cognitive functioning can contribute to the early diagnosis of the development of the disease. Methods: It was a cross-sectional study that involved dementia patients, people in high-risk groups and control people with normal cognition. The spectral power of the alpha, beta, theta and delta bands and alpha/theta ratio were examined. Pearson correlation coefficients were done to check the relation between EEG parameters and MMSE scores. Results: The scores of MMSE were clearly differentiated between groups with the minimum score being recorded in the dementia patients, with intermediate scores in high-risk individuals, and the highest scores in the controls who showed no impaired cognitive score. EEG data indicated significant decreases in alpha and beta activity and significant increases in theta and delta power in dementia patients and with the high-risk individuals less severe abnormalities were observed. Conclusion: MMSE and EEG when used together offer a good method of distinguishing the cognitive states in relation to various levels of dementia. The alpha/theta ratio as an EEG-based biomarker demonstrates a great potential of early detection and monitoring of cognitive impairment.

Dementia, mini-mental state examination, electroencephalography oscillations, alpha/theta ratio, cognitive decline.