Alzheimer's disease and COVID-19

Studies have shown that Alzheimer's disease (AD) patients are at an increased risk of morbidity and mortality from SARS-CoV-2, the virus that causes COVID-19. AD is the most common cause of dementia worldwide and is clinically defined by amyloid beta plaques, neurofibrillary tangles, and activation of the brain's immune system. While COVID-19 has been known to more severely impact elderly populations, AD patients have been shown to have a higher rate of SARS-CoV-2 infection compared to cognitively normal patients. The disproportionate risk of COVID-19 in AD patients is thought to arise from an interplay of biological and social factors between the two diseases. Many common biological pathways are shared between COVID-19 and AD, notably those involved in inflammation. Genetic factors that put individuals at risk for AD, such as the APOE4 genotype, are associated with worse outcomes during SARS-CoV-2 infection. Cognitive impairment in AD may prevent patients from following proper public health guidelines, such as masking and social distancing, increasing their risk of infection. Additionally, studies have shown cognitively normal COVID-19 patients are at an increased risk of AD diagnosis following recovery, suggesting that COVID-19 has the potential to cause AD.