MAPT and Alzheimer disease: 2022). The 18F‐FDG PET scans reveal a scattered or patchy drop‐in brain activity in MS, tied to damaged nerve fibers, while AD shows a distinct pattern of reduced activity in the temporoparietal and posterior cingulate areas (Londoño et al. 2022). CSF tests can also provide more insight. In AD, Aβ1‐42 levels are typically low, while tau levels are high. In contrast, MS usually presents with normal Aβ1‐42 levels and only a slight increase in tau, unless AD itself is present (Londoño et al. 2022).