APP and Parkinson disease: Again, as for PD, severity of symptoms of both AD and COVID-19 are age-related and, interestingly, both are pathologically to mechanistic factors including the deposition of APP and to the activation of putative cell-death mechanisms that include excitotoxicity due to NMDA-receptor activated uptake of Ca++ in addition to microglial-mediated proinflammatory responses shared by COVID-19 and AD.