ACE2 and infection: During the infection process, SARS-CoV-2 uses the olfactory nerve to pass through the cribriform plate of the ethmoid bone to cause brain invasion (45, 46), which results in a rapid, transneuronal spread of the SARS-CoV-2 to relevant regions of the brain, which in turn interacts with ACE2 expressed on the surface of brain neurons (47–49).