Figure 2. Cortical thickness and hippocampal volumes.

The brain images show cortical maps of differences in thickness when comparing the different AD subtypes with the healthy controls. A general linear model was fitted at each vertex. Study group was entered as independent variable and TIV as a covariate. Z Monte Carlo simulations were conducted for cluster-forming with a threshold of p ≤ 0.001 (two-sided), yielding clusters corrected for multiple comparisons. Only vertexes belonging to clusters surviving this correction are displayed. Significant clusters were mapped on standard templates depicted in lateral (first two images on each row) and medial (last two images on each row) views, both for left (L) and right (R) hemispheres. The coloured bar illustrates the significance level of the differences (i.e. less cortical thickness in the AD patients) from dark blue (p ≤ 0.05) to light blue (p ≤ 0.00001). All these results stand after controlling for age, gender, years of education, and APOE ε4 status (data not shown). The boxplot represents the averaged hippocampal volume controlling for TIV, age, years of education, and APOE ε4 status. Hence, the y-axis represents adjusted and standardized values. Box values represent median and confidence intervals. The groups’ sizes are specified in Fig. 1 and Table 1. AD = Alzheimer’s disease.