The main effect of factor condition (HC n = 395, MCI n = 156, AD n = 135) on the six ROIs. The VBM results were thresholded for p < 0.05 FWE (corrected) and adjusted for total intracranial volume, age and education. The significant clusters of voxels are shown on a 3D reconstruction of the Cerebellum, the Brainstem and the Diencephalon (sagittal to coronal view from left to right). The color bar represents F value ranges and reflects the significance of volume reduction across the three groups. The main volume reduction occurred in the Nucleus Basalis of Meynert (NBM) 35 voxels F 33.89, in the Ventral Tegmental Area (VTA) 65 voxels F 23.79, in the Dorsal Raphe (DR) 132 voxels F 28.66 and in the Locus Coeruleus (LC) 64 voxels F 21,46. See Tables S3 and S4 in Supplementary Materials with Figure 2 for further details.