Characterizing Non-stationarity in Alzheimer’s Disease and Mild Cognitive Impairment by Means of Kullback-Leibler Divergence

The aim of this study was to characterize the non-stationarity level of resting-state EEG in patients with dementia due to Alzheimer’s disease (AD), subjects with mild cognitive impairment (MCI) and healthy controls. A frequency-dependent implementation of the Kullback-Leibler divergence was used to characterize non-stationarity patterns. The results showed a statistically significant increase in non-stationarity for AD patients with respect to controls in the 1–70 Hz frequency range, as well as a less pronounced increase for MCI subjects with respect to controls. These results suggest that EEG activity during short time windows consists of more structured oscillations than that of AD patients or MCI subjects.