The morbidity and mortality rates for COVID-19 are increased in subjects with AD, which is possibly due to the AD-related pathological changes and factors, such as elevated proinflammatory molecules, an advanced age, BBB disruption, presence of APOE epsilon4 (APOE ε4) allele, diabetes mellitus, and lifestyle factors [33, 34]. The gene discussed is APOE; the disease is Alzheimer disease.