That SARS-CoV-2, the culprit of the COVID-19 pandemic, is also associated with neurological symptoms isn’t entirely surprising, given some evidence that its close relatives, MERS-CoV and SARS-CoV-1, have been associated with neurological symptoms too. But the proportion of patients developing such symptoms—and their mounting collective numbers—has startled some scientists.
As this cohort grows, so too does the global effort to investigate how SARS-CoV-2 causes such symptoms. The picture so far remains somewhat puzzling. Autopsy studies—which have been limited—have found clear signs of damage in dozens of brains of COVID-19 patients. Although traces of the virus have been reported in some brain specimens, in many cases it is nowhere to be found. While the question of whether SARS-CoV-2 directly infects the brain remains unresolved, researchers are exploring other mechanisms whereby it could affect the human brain.
“I think all of us probably . . . would agree that there is no overwhelming infection of the brain,” notes Avindra Nath, a neurovirologist at the National Institute of Neurological Disorders and Stroke. “If there is, it’s a very, very miniscule amount. That cannot explain the pathology that we see. It has to be something more than that.”