In the AD group, downregulated genes in Exc in level 1 spots were associated with responses to mitochondrial dysfunction (e.g., UQCRQ, ATP6V1G2, POLR2F), oxidative stress (e.g., PTGES3, MT3, HAGH), and protein clearance (e.g., PSMD8, CHMP4B, VPS4A), suggesting greater functional impairment in Exc near large vessels in AD (Fig. 5C). This evidence concerns the gene PSMD8 and Alzheimer disease.