evidence: Even if growing suspicions turn out to be right, it leaves the question of how the virus would be doing its damage. Blood clots throughout the body seem to be emerging as a hallmark of the disease. But, in rare cases some viruses, like the virus that causes chickenpox, can target the brain’s blood vessel system and other tissue, wreaking havoc on the brain’s blood supply — but it is not clear that COVID-19 does the same thing. [...] Respiratory problems from COVID-19 can cause oxygen levels to drop steeply, which is dangerous for the brain. And the out-of-control immune responses, kidney damage, clotting, and other severe symptoms sometimes seen with COVID-19 could easily spell trouble for the nervous system. [...] "We know that other viruses can hop from the nose, through the olfactory bulb, into the brain and we know that COVID can cause neurological symptoms," Datta says. "Is that what’s going on here?"