How COVID-19 Affects The Brain : Short Wave Many patients who are hospitalized for COVID-19 continue to have symptoms of brain injury after they are discharged. For many, brain function improves as they recover, but some are likely to face long-term disability. As NPR science correspondent Jon Hamilton explains, research into all the ways the coronavirus affects the brain is ongoing but research shows it can affect everything from loss of smell to memory problems. Read Jon's piece here.

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How COVID-19 Affects The Brain

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You're listening to SHORT WAVE from NPR.

EMILY KWONG, BYLINE: Hey, everybody. Emily Kwong here with our favorites brain reporter, NPR science correspondent Jon Hamilton. Hi, Jon.


KWONG: Hi. So you're here today to talk about how a disease that attacks the lungs can also damage the brain. I'm talking, of course, about COVID-19.

HAMILTON: Yes. It's continuing to infect and kill record numbers of people in the US. In fact, I saw just in the past seven days, around 3,000 people have died every day. And even though a vaccine is being rolled out, it looks like the number of cases will keep going up for weeks, if not months.

KWONG: Yeah. And some of these cases have shown us that COVID can really do damage beyond your lungs. What can COVID-19 do to your brain?

HAMILTON: So you may remember, way back in April, I interviewed David Williams. He's in his mid-50s. He's a veteran service coordinator at the University of Central Arkansas. And he spent more than a week on a ventilator after he got COVID-19.

KWONG: Yeah, I do remember David. He was on SHORT WAVE a while back.

HAMILTON: Yeah. And when he got off the ventilator, his return home was really pretty rough. Here's what he told me.

DAVID WILLIAMS: My cognitive thinking was was off. It was hard for me to try and recall things or - because, like, right now, it takes me a while to think about the words I need to be able to say now. But I'm slowly getting it back.

KWONG: Wow. Yeah, you can hear his speech kind of struggling there. But how does the SARS-CoV-2 virus do that to somebody?

HAMILTON: That's something that scientists are really just beginning to understand.


HAMILTON: In fact, it was just last month that a medical journal finally published a study that provided some detailed information about the brains of people with COVID-19 who died. And what the researchers found was kind of disturbing.

KWONG: Today on the show, COVID-19 and the brain. It turns out there are a lot of ways the disease can affect memory, thinking, movement, even mood.

HAMILTON: Sometimes the damage is permanent. And people whose brains are injured by COVID may even face a higher risk of developing Alzheimer's disease.


KWONG: So Jon, when COVID-19 first showed up in the U.S., it was all about whether a person would end up on a respirator - remember? - whether they could breathe, whether they could potentially die. And it was very focused on the respiratory system overall. So when did scientists start thinking about how the virus could hurt someone's brain?

HAMILTON: There are two answers to that.


HAMILTON: Doctors realized really quickly that patients who ended up in the hospital with COVID, they often developed these blood clots that could travel to the brain and cause a stroke. They also knew right away that some patients were suffering brain damage because their lungs were so impaired, they couldn't deliver enough oxygen to the brain. What scientists didn't know was whether the virus was directly affecting the brain in some way.

KWONG: And were there suspicions, hints of that?

HAMILTON: Yeah, well, neurologists got worried pretty early on. And the reason was that there were these reports coming out of China that people in the early stages of COVID-19 could even lose their sense of smell. I think you did an episode about that back in April.

KWONG: We did. I learned how to say anosmia, which is the loss of smell that you described. And a few friends and family members had that symptom when they got COVID. And I even know someone whose sense of smell has not recovered even though it's been months.

HAMILTON: Yeah. Over time, it became clear that the loss of smell was this very distinct symptom of the disease.

KWONG: Yeah.

HAMILTON: I talked to a neurologist about that. His name is Dr. Gabriel de Erausquin. He's at the Long School of Medicine at UT Health in San Antonio.

GABRIEL DE ERAUSQUIN: Loss of smell can occur, for instance, if you just have a very congested nose. But when it is a specific and persistent sign, it's associated with a variety of brain diseases, including Alzheimer's, dementia, Parkinson's disease, schizophrenia and others.

KWONG: Yeah. I know that some brain diseases can cause you to lose your sense of smell. But is he saying that's what's going on with these COVID-19 patients?

HAMILTON: Not exactly. His point is that the sensory nerve cells that let us smell things are connected to the brain. So if the SARS-CoV-2 virus gets into those cells - and it does - it has a direct path to invade the brain.

KWONG: Right. Not good. And I've never heard of that before. I mean, is brain damage a common side effect of viral infections like the coronavirus.

HAMILTON: I wouldn't call it common. But brain scientists knew that previous epidemics and pandemics had caused brain damage.


HAMILTON: The 1918 flu, you know, the one that killed all those people, a number of scientists think it was also responsible for an outbreak of something called encephalitis lethargica. That's this neurological problem where people develop weakness or tremor or trouble moving. Sometimes they even fall into a coma. Brain scientists also knew that other coronaviruses could get into the brain. So they were watching SARS-CoV-2 pretty closely.

KWONG: Now, Jon, it's been a year since the coronavirus emerged. And millions of people have been infected. So why has it taken until now to know how COVID-19, the disease, affects our brains?

HAMILTON: Yeah, good question. One reason is that scientists haven't been able to study that many brains from people who got COVID-19 and then died.

KWONG: But why is that? - because we've had hundreds of thousands of deaths just in the U.S. So I'd assume - not to be too grim here. But I'd assume that there were plenty of COVID-19 patient brains to look at.

HAMILTON: There are in theory. But they aren't that easy to get because autopsies generally aren't being done on most people who die of COVID-19. There are several reasons for that. One is, of course, hospitals have been overwhelmed. And autopsies are one way you might spread the virus. And there have been lots of shortages of personal protective equipment you need to do an autopsy safely. Plus, there's this special kind of gruesome problem when you do a brain autopsy.

KWONG: Yes. OK. A disclosure to any squeamish listeners out there - you may want to skip the next 30 seconds of this podcast because, Jon, you're going to tell me exactly how a brain autopsy works.


KWONG: How does it work?

HAMILTON: I learned about this from Dr. Avi Nath at the National Institute of Neurological Disorders and Stroke. So why don't I let him describe it?

AVI NATH: In order to conduct an autopsy, you have to open the skull to get the brain. And that produces a lot of aerosol or dust from the bone itself. You need something - what's called a vacuum saw so that when you cut the bone, the dust can be collected in the vacuum saw by itself. Those were not available to most people.

HAMILTON: It turns out these saws are pretty rare, except in places that work with brain tissue that might be highly contagious. And most places just didn't have one.

KWONG: Got it. OK. But I'm guessing scientists were able to get ahold of both brain samples and the necessary tools to safely look at these brains.

HAMILTON: Yeah, they have. Dr. Nath is one of the authors of a study that looked at 19 brains taken from people who died shortly after they got COVID-19. And his team saw a lot of damage. And what he told me was that they found something that could help explain that damage.

NATH: What we found was that the very small blood vessels in the brain were leaking, and it wasn't evenly. You would find a small blood vessel here and a small blood vessel there. So you get these small punctate - is the word that we often use to say small foci or punctate areas of pathology in these small blood vessels.

KWONG: Punctate - what does that mean, Jon?

HAMILTON: Yeah, I had to look it up. It just means tiny punctures. What Nath is saying is it looks like the infection can lead to brain damage by causing these tiny blood vessels to get punctured and leak. It's like having a bunch of little strokes happening all over the brain.


HAMILTON: There's bleeding. You know, there's inflammation - all kinds of bad stuff going on. But Nath told me one thing they didn't find in these areas was the coronavirus itself. So it may be that the problem isn't that the virus is killing cells directly, but that there's a sort of collateral damage when our immune system tries to protect us from the virus.

KWONG: Yeah. And what you're saying, too, is that COVID-19 overall is just bad for our bodies and potentially our brains.

HAMILTON: Yeah, definitely one more reason to wear a mask.

KWONG: Absolutely, and do all the things to keep from getting it. But, Jon, OK, for people who get really bad COVID-19 that affects their brain, what is that even like? How does it change them?

HAMILTON: We've already talked about people who have trouble remembering things or making plans. Then there are people who develop depression or mood problems. And it turns out the brain is also really important for maintaining a lot of bodily functions. Nath told me about some COVID-19 patients who are having trouble with those.

NATH: They complain of heart racing. When they stand up, they get quite dizzy. They can have, you know, urinary problems or gastrointestinal problems.

HAMILTON: These are the so-called autonomic problems. And just to complete the list, certain kinds of brain damage can make you feel this extreme fatigue.

KWONG: Wow. That is - that's really tough. And how long do all of these consequences last?

HAMILTON: Not clear. Some people get better in weeks. Some have been recovering for months and are still struggling with brain problems. And sadly, most of the recovery from brain damage happens within a year or so. So for some people, these problems are probably here to stay.

And now there's a new thing - neurologists are worried that even people who recover may face a higher risk of getting Alzheimer's disease years from now. I talked to Heather Snyder. She's in charge of scientific operations at the Alzheimer's Association. And she told me they are really concerned about the immune system's reaction to the virus and about those leaky blood vessels.

HEATHER SNYDER: We know that those are important in Alzheimer's disease, and we're seeing them play a key role here in COVID-19. And what that might mean in later life, we need to be asking that question now.

KWONG: Yeah, the phrase more research is needed comes to mind.

HAMILTON: Yeah, it does. So the Alzheimer's Association is actually teaming up with brain researchers in more than 30 countries to start doing that research.

KWONG: OK. Jon, I'm wondering, do you have any other good news for our brains to absorb when it comes to this virus?

HAMILTON: Well, there's some. Of course, the vaccines are rolling out now, and they protect the brain as well as your body from COVID-19. And people who have brain problems from COVID-19 do tend to get better. You remember David Williams, that guy who spent eight days on a ventilator?

KWONG: Yeah. Yeah, how's he doing now?

HAMILTON: Well, I was curious about that myself, so...


HAMILTON: ...I called him up.

WILLIAMS: Hey, Mr. Hamilton. I'm all ready.

HAMILTON: And he told me he doesn't need an oxygen mask anymore. He's been able to get back to work part time. And I could tell he wasn't struggling as hard to find the next word in a sentence nearly the way he was. But Williams told me that his brain, you know, it still hasn't fully recovered.

WILLIAMS: It's not as bad as it was when I was speaking to you back in April. But, yes, I still have a few cognitive issues.

HAMILTON: Williams told me it's really hard now for him to remember the names of students he works with at the university. And he's got other problems. His lungs are scarred. His joints ache. He feels tired a lot. He can't sleep. He says COVID-19 has done more damage to his body and brain than all his time as a Marine fighting in Afghanistan.

WILLIAMS: You go to war and, you know, you dodge millions of bullets. But you come back and one bullet takes you out, you know. I was like, no, I don't want that. I don't want to go out like this.

KWONG: I think that's what a lot of people forget about this virus. It's not a binary, where you're either in a high-risk group and could die or you're fine; it's more complicated than that.

HAMILTON: Exactly. I mean, to me, David Williams is a reminder that surviving COVID-19 is not the same as fully recovering from it. And of course, most people don't get as sick as he did, but tens of millions of people have been infected just in the U.S. So that means long after the pandemic is over, there will probably be a lot of people like David whose brains still aren't working right.

KWONG: Well, David Williams, we wish you well in your recovery. Jon, thank you for following up with him and so much for bringing us this information and coming on the show.

HAMILTON: Always glad to, Emily.


KWONG: This episode was produced by Rebecca Ramirez, edited by Gisele Grayson and fact-checked by Ariela Zebede. Gilly Moon was our audio engineer. I'm Emily Kwong. Thanks for listening to SHORT WAVE from NPR.


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