Electroencephalogram background activity characterization with Detrended Moving Average in Alzheimer´s disease patients

The aim of this study was to analyse the electroencephalogram (EEG) background activity in Alzheimer´s disease (AD) with the Detrended Moving Average (DMA) method, a new approach to quantify correlation properties in non-stationary signals with underlying trends. EEGs were recorded from the 19 scalp loci of the international 10-20 system in 11 AD patients and 11 age-matched controls. Our results showed two scaling regions in all subjects´ channels, with a clear bend when their corresponding slopes (a₁ and a₂) were distinctly different. With the exception of electrode T4, the a₁ values were lower in control subjects than in AD patients, with significant differences at T5, P3, P4 and O1 (p < 0.01, Student´s t-test). On the other hand, a₂ values were higher in control subjects than in AD patients, with significant differences only at F4. Furthermore, we evaluated the ability of a₂ to discriminate AD patients from control subjects at these electrodes using ROC plots. We obtained a maximum accuracy of 81.82% at O1 with a₁ and at F4 with a₂. These findings suggest that the scaling behaviour of the EEG is sensitive to AD and that the DMA method could help to increase our insight into brain dysfunction in AD.