Can the SARS-CoV-2 virus damage the brain?

A certain very famous politician came down with Covid-19 recently, and has been acting even more erratically than usual. This has led a number of pundits (and some doctors) to speculate that this politician’s behavior might be a symptom of his ongoing infection. Could this be true?

Well, maybe. Most of the attention around Covid-19 has been focused on the damage that the SARS-CoV-2 virus causes in the lungs, which can lead to difficulty breathing, the need for a respirator, and even death. The virus has the ability to replicate explosively in a person’s lungs, not only causing serious damage but also triggering an over-reaction by the immune system, a so-called “cytokine storm” that itself can kill you, even if the virus doesn’t.

However, numerous reports have shown that the virus gets into many other tissues besides the lungs, including the brain. Just this week, a new study out of Northwestern University School of Medicine found that over 80% of patients with Covid-19 had at least some neurological symptoms. 80% is a startlingly high number.

While that sounds alarming, let’s look at the details. The new study looked at 509 Covid-19 patients, all of them admitted to hospitals in Chicago. These were “consecutive” patients, meaning that the investigators didn’t cherry-pick their subjects, but just took 509 in a row. That seems sound.

Most of the symptoms, although definitely affecting the brain, were mild. 38% of the symptoms were headaches, and 44% were “myalgias”, which refers to aches and pains throughout the body. (Note that some patients had more than one type of symptom, so the numbers in the study add up to more than 100%.)

However, 32% of the patients had encephalopathy, which can be much more serious than a simple headache. According to NIH, encephalopathy can involve:

“loss of memory and cognitive ability, subtle personality changes, inability to concentrate, lethargy, and progressive loss of consciousness.”

Does this sound like any of the behaviors we’ve seen in our most famous infected politician?

The new study is not the first one to report neurological symptoms caused by Covid-19. Back in July, a research team from University College London reported multiple cases of neurological problems in their cohort of 43 patients. They observed not only encephalopathy (in 10 patients), but also encephalitis in 12 other patients and strokes in 8 more. Some of the patients in that study were reported as experiencing “delirium/psychosis,” and strokes often cause permanent brain damage. Clearly, the SARS-CoV-2 virus can cause serious health problems, and disturbing behavioral changes, if it gets into the brain.

None of this means that any current political leader is experiencing an altered mental state. We don’t have a direct test that measures whether the virus is present in a person’s brain, so all we can do is observe symptoms and make inferences from those. The best available evidence today, though, shows that for anyone with Covid-19, neurological problems are definitely something we should be worried about.