Stereology-based quantitative analysis of microglia double-labeled for IBA1 and MHC2. The total number of microglia did not differ significantly between the nondemented and the AD groups (A). Within the AD group, neither total microglial cells (B) nor any of the microglia subtypes (D, F, and H) was observed to increase with the clinical progression of the disease. However, IBA1+MHC2− microglia (C) was significantly more abundant in the nondemented group, and IBA1−MHC2+ microglia (G) were significantly more abundant in the AD. There was a trend toward increase in IBA1+MHC2+ microglia in the AD group (E). Counts in each case are not density measures, but estimates of the number of cells per 1 cm-long full-width cortex from a single section of temporal isocortex. Data are expressed as individual values with means ± SEM (A, C, E, and G) or 95% confidence interval of the mean slope (B, D, F, and H).∗P < 0.05, †P < 0.0001.