NEFL and COVID-19: As regards the possible mechanisms of cognitive impairment after COVID-19 recovery, a study of 310 patients showed that those with new neurological symptoms after healing had higher levels of t-tau, neurofilament light chain (NfL), GFAP, and p-tau-181 in their blood, as well as indicators of inflammation such as C-reactive protein, compared to patients without neurological symptoms after healing, suggesting that former patients could have an underlying Alzheimer-related pathology [115].