Relation between Apolipoprotein E in Alzheimer's Disease and SARS-CoV-2 and their Treatment Strategy: A Review

COVID-19, which primarily affects the pulmonary system, turned out to be a global pandemic, whereas the effects on other systems are still unknown. SARS-CoV-2, binds to angiotensinconverting enzyme 2 (ACE2) receptors in the lungs, causing pneumonia-like symptoms. The same ACE receptors are also present in organs other than the lungs. Therefore, there is a need to study the impact of coronavirus on other human body organs. Recently, UK Biobank reports on the genetic risk factor of the virus attack. A double mutation in the apolipoprotein E (APOE4) allele has shown a significant role in COVID-19. The same APOE4 mutation has already been proven to hold a key role in developing early-onset Alzheimer's disease (EOAD). Despite this data, Alzheimer's disease is believed to be a comorbidity of COVID-19. Previous virus attacks on the same viral family, Coronaviridae, produced neurological effects like neurodegeneration, neuronal inflammation, and other central nervous system-related dysfunctions. Since the long-term implications of COVID-19 are unknown, more research into the impact of the virus on the central nervous system is needed. Both COVID-19 and AD share a common genetic factor, so that AD patients may have a greater risk of SARS-CoV-2. Here, in this review, we have briefly discussed the role of APOE4 in the pathogenesis of AD and SARS-CoV-2, along with their treatment strategy, current scenario, and possible future directions.