# An eLORETA Longitudinal Analysis of Resting State EEG Rhythms in Alzheimer's Disease
## 3 Results  
The methodology explained in Section 2.3 was applied to the EEG recordings and produced the following results. The EEG preprocessing and the grouping of power current density values according to the four regions of interest were executed with Matlab (R2018a). A statistical analysis was carried out for determining whether the differences between values at T0 and T1 were significant. For this purpose, the Wilcoxon rank sum test [48] was performed under the null hypothesis that, for each patient, the medians of the current density values at time T0 do not differ from those at time T1. The significance level was set at 5%, which means that there is a 5% risk of concluding that a difference exists when there is no actual difference. So, the difference between T0 and T1 is statistically significant when the \(p\)-value is less than 0.05. Tables A1-A3 (see Appendix A) report the p-values resulting from the statistical analysis for each sub-band and each region of interest. F. L., O. L., P. L., and T. L. stand for Frontal Lobe, Occipital Lobe, Parietal Lobe, Temporal Lobe, respectively. The p-values statistically significant which are consistent with the expected results are highlightedin gray. Patient 03 shows a widespread increase of power density in delta and theta bands, and a decrease in alpha 1 (parietal region) and beta 2 (temporal lobe) bands. Patient 32 exhibits a greater activation of delta sources in all regions; an increasing power in theta band in the occipital, parietal, and temporal lobes; and a lower activity in alpha 1, alpha 2, and beta 1 bands in the frontal lobe and in beta 2 band in the frontal and occipital lobes. Patient 41 shows a greater power in delta (occipital and parietal areas) and theta (occipital and temporal regions) bands, and a lower activation in alpha 1 (frontal lobe), alpha 2 (frontal, parietal and temporal lobes), beta 1, and beta 2 bands in all lobes. Patients 51 and 71 reveal a widespread decrease of power density for alpha 1, alpha 2, beta 1, and beta 2 bands. As for patient 164, the results are the same except for the parietal lobe in alpha 1 band: in this case the power density increases. Patient 180 displays a widespread greater power in delta and theta bands. Patient 184 shows an increased activation in delta (temporal lobe) and theta (parietal and temporal lobes) bands; the power density decreases in the frontal and occipital regions for alpha 1 and alpha 2 bands, in the occipital lobe for beta 1 band, in the frontal, occipital, and parietal lobe for beta 2 band. The bar graph in Figure 1 summarizes the statistically significant results highlighted in gray in Tables A1-A3. The graph reveals that most significant variations were detected in higher frequency bands. In particular, six patients show a decreasing power density in alpha 1 and alpha 2 (frontal lobe) bands, in addition to beta 2 (frontal and occipital lobes) band. As for delta and theta bands, the power density increases in four subjects at most, except for the temporal lobe in theta band: in this case, the increase is detected in five patients. Figures 2-9 show the boxplots of the power density values of each patient at time T0 and T1, for each frequency sub-band and each region of interest. From the analysis of the results, our hypothesis is that the outcome not consistent with previous findings are due to the passage from MCI to a mild AD condition. Therefore, the not yet severe stage of the disease, together with the inter-subject  
Figure 2: Boxplot of the power current density of patient 03 at time T0 and T1 for each frequency sub-band and each region of interest (frontal, occipital, parietal, and temporal). Figure 3: Boxplot of the power current density of patient 32 at time T0 and T1 for each frequency sub-band and each region of interest (frontal, occipital, parietal, and temporal). Figure 4: Boxplot of the power current density of patient 41 at time T0 and T1 for each frequency sub-band and each region of interest (frontal, occipital, parietal, and temporal).