ACE2 and Alzheimer disease: APOE4 as a significant genetic risk factor for AD also interacts with angiotensin-converting enzyme 2 (ACE2) to hinder SARS-CoV-2 infection and influence inflammation levels.605 Some variants in the interferon-responsive gene OAS1 may lower its expression and potentially increase the likelihood of AD and severe COVID-19, through excessive release of pro-inflammatory signals in myeloid cells such as microglia and macrophages, further leading to cell death.606 SARS-CoV-2 affects key pathological changes, such as Aβ, tau, and neuroinflammation, promoting cognitive impairment.