Covid brain damage is via same mechanism as Alzheimer's, per this article in "Alzheimer's and Dementia." Previously mentally-fit Covid patients with encephalopathy had higher levels of relevant biomarkers than did non-Covid Alzheimer's controls.
Along with decreases in average life span, we will be seeing decreases in average IQ - unless leronlimab for long-haulers can reverse it.
Phosphorylated tau is the "axon strangler" in Alzheimer's and neurofilament light is the evidence that axons have been strangled.
"Blood levels of total tau (t-tau), phosphorylated tau181 (p-tau181), glial fibrillary acidic protein (GFAP), and neurofilament light (NfL) were significantly elevated in COVID-19 patients with encephalopathy and those who died in the hospital, reported Thomas Wisniewski, MD, of New York University Grossman School of Medicine in New York City, and co-authors."
"Levels of NfL, GFAP, and ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) were as high or higher in the short term among hospitalized COVID-19 patients without a history of dementia than they were among Alzheimer's patients who never had COVID-19"