The Coronavirus or SARS-CoV-2 that causes COVID-19 does not directly infect the brain but can still inflict significant neurological damage, said a new study from neuro experts at Columbia University Vagelos College of Physicians and Surgeons.
“There’s been considerable debate about whether this virus infects the brain, but we were unable to find any signs of virus inside brain cells of more than 40 COVID-19 patients,” says James E. Goldman, professor of pathology & cell biology, who led the study with Peter D. Canoll, professor of pathology & cell biology, and Kiran T. Thakur, an Assistant Professor of Neurology.
“At the same time, we observed many pathological changes in these brains, which could explain why severely ill patients experience confusion and delirium and other serious neurological effects–and why those with mild cases may experience ‘brain fog’ for weeks and months.”
The study, published in the journal Brain, is the largest and most detailed COVID-19 brain autopsy report published to date, suggests that the neurological changes often seen in these patients may result from inflammation triggered by the virus in other parts of the body or in the brain’s blood vessels.
No Virus in Brain Cells
The study examined the brains of 41 patients with COVID-19 who succumbed to the disease, ranged in age from 38 to 97 and half had been intubated and all had lung damage caused by the virus. Many of them were of Hispanic ethnicity. All of the patients had brain MRI and CT scans.
To detect any virus in the brain, the researchers used multiple methods including RNA in situ hybridization to detect viral RNA within intact cells; antibodies that can detect viral proteins within cells; and RT-PCR, a sensitive technique for detecting viral RNA. But they found no coronavirus in the patients’ brain cells. They did detect very low levels of viral RNA by RT-PCR, but it was likely due to virus in blood vessels or leptomeninges covering the brain.
“Though there are some papers that claim to have found virus in neurons or glia, we think that those result from contamination,” Canoll says. Despite the absence of virus in the brain, they noticed many areas with damage from a lack of oxygen. They all had severe lung disease, so it’s not surprising that there’s hypoxic damage in the brain, caused by strokes, he said.
Persistent Neurological Problems in Survivors
Goldman says that more research is needed to understand the reasons why some post-COVID-19 patients continue to experience symptoms. The researchers are now examining autopsies on patients who died several months after recovering from COVID-19 to learn more.
They are also examining the brains from patients who were critically ill with acute respiratory distress syndrome (ARDS) before the COVID-19 pandemic to see how much of COVID-19 brain pathology is a result of the severe lung disease.