While no evidence of any viral RNA was detected in patients brain cells, investigators found a significant amount of neurological damage.
A recent study conducted by investigators from the Columbia University Irving Medical Center has found that SARS-CoV-2, the virus that causes COVID-19, likely does not directly infect the brain, but is still able to inflict a significant amount of neurological damage.
Results from the study were published in the journal Brain.
"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," James E. Goldman, lead author on the study said. "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."
For the study, investigators examined 41 patients who died because of COVID-19 during a hospitalization. Of the patients, ages ranged between 38 and 97 years of age, around half had been intubated and all of the patients had some form of lung damage.
The investigators performed multiple types of testing on more than 2 dozen brain regions, including RNA in situ hybridization and RT-PCR, to try and detect any viral RNA within intact cells in the brain, but found no evidence of any being there.
While no viral RNA was detected, the investigators found a significant amount of brain pathology, including areas of stroke and a large amount of microglia, a type of immune cell that resides in the brain.
Most of the immune cells were found in the lower brain stem, an area which is known to regulate heart and breathing rhythms and levels of consciousness.
"We've looked at more brains than other studies, and we've used more techniques to search for the virus. The bottom line is that we find no evidence of viral RNA or protein in brain cells," Goldman said. "Though there are some papers that claim to have found virus in neurons or glia, we think that those result from contamination, and any virus in the brain is contained within the brain's blood vessels."