To understand which Nox isozyme plays a key role in AD pathogenesis, we intracerebroventricular (ICV) injected β‐amyloid (Aβ) into the brain tissue of WT, Nox1 KO, Nox2 KO, and Nox4 KO mice (ICV, −0.1 mm AP, +1.0 mm ML, −3.0 mm DV). Here, NOX4 is linked to Alzheimer disease.