COVID-19 can damage the brain, but without infecting it, study suggests

COVID-19 damages brain without infecting it, study suggests Brain abnormalities could explain the confusion and delirium of severe COVID-19. CIDRAP

Although SARS-CoV-2 probably does not infect the brain, it can damage it significantly, a new study of autopsies of 41 COVID-19 patients finds.

Researchers at Columbia University say that they found no signs of virus inside the patients' brain cells but saw many brain abnormalities that could explain the confusion and delirium seen in some patients with severe coronavirus and the lingering "brain fog" in those with mild disease.

The study, which the authors called the largest COVID-19 brain autopsy report thus far, involved analysis of samples from autopsies conducted from March to June 2020 and was published late last week in Brain. The findings, they said, suggest that the inflammation triggered by the coronavirus in other parts of the body or in the brain's blood vessels may have caused the neurologic abnormalities seen in the autopsies.

The brain damage consisted of areas starved of oxygen, many of them hemorrhagic, which the researchers said were likely caused by blood clots that temporarily blocked the flow of oxygen. Many activated microglia, or immune cells in the brain that can be activated by pathogens, were also identified.

"We found clusters of microglia attacking neurons, a process called 'neuronophagia,'" co-senior author Peter Canoll, MD, PhD, said in a Columbia University press release.

Because no virus was observed in the brain, he said that the microglia may have been activated by inflammatory cytokines, which are tied to coronavirus infection. "At the same time, hypoxia [reduced oxygen from COVID-19] can induce the expression of 'eat me' signals on the surface of neurons, making hypoxic neurons more vulnerable to activated microglia." ...