Short Wave - Smell Therapy

Episode Date: April 8, 2021

A curious symptom of COVID-19 that can stick with patients for a long time is loss of smell. Researchers don't know exactly how prevalent the loss of smell ism and while most people recover from it, some will not. This has given new life to a very specific treatment: smell training. Emily Kwong talks to the Atlantic's science reporter Sarah Zhang about how practicing how to smell might help those who've lost their sense of smell. For more on smell training, read Sarah's piece in The Atlantic. You can email Short Wave at [e-mail] pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hey, everybody. Emily Kwong here. A curious symptom of COVID-19 that can stick with patients for a long time is loss of smell. You may remember it was around this time last year that we dropped an episode about doctors reporting loss of smell in people who later tested positive for COVID-19. Now, loss of smell is recognized as an official symptom. But researchers don't know exactly how prevalent anosmia loss of smell and hyposmia, partial loss of smell, is. But one European study found that 86% of patients with mild COVID cases reported losing their sense of smell. And while most recovered it, some didn't.

This has given new life to a very specific treatment. Smell training. It's like physical therapy, but for your nose, done regularly over weeks. or maybe months. And Sarah Zang, science reporter for the Atlantic, wanted to know more about it. How does it work? And does it actually work? One of the smell trainees she talked to is Ruby Martinez in Texas.

So Sarah, let's start with stories from some of the folks you talked to who lost their sense of smell. Maybe let's start with Ruby Martinez. Yeah. What happened with her? Yeah, so Ruby first noticed us because she was eating a banana and she was just kind of like, chewing and chewing. She was like, huh, I don't taste anything. So she also lost her sense of taste. And then she was like, well, I don't smell anything either. And that's when she told me she kind of started freaking out. So she went to go eat some chips and some pickles and she still

couldn't taste her smell anything. She went to smell about her perfume and like still nothing. Over the next few weeks, you know, strange things started to happen. You know, her smell did start to come back. But her smell has come back in really, really strange ways as well. You know, she told me that a lot of, you know, things just don't smell the way they used to. So that can be like shampoo or soap or perfume. She told me that she used to really like her boyfriend's cologne, but now it just smells like super calmically and she like really hates it and she can't wear it anymore. One of the other really strange things is that she works in the doctor's office and they have to wash her hands a lot. And the hands that they have at work, she remembers it just

smelled kind of, you know, generic and fruity. But now she says it smells exactly like Burger King Whoppers. That's deeply unfair. It's just unfair, right? That all these things that are supposed to smell enticing, like her own boyfriend's cologne, smells terrible. You know, there are other stories that people have had where you can smell worse things than whoppers, right? Like garbage or sewage, and, you know, some people have reported that they'll try to drink some coffee and it'll just taste their garbage. And that's honestly really, really distressing. Wow. Okay. So how did it affect Ruby to suddenly lose her sense of smell. Yeah, I think she found it really, really strange.

And it was really, you know, she told me she's someone who loves to eat. And she was hoping that, you know, in a few weeks her smell could come back so she could go out for a birthday dinner. And she did go out for a birthday dinner, but her smell didn't come back. And she just remember it was kind of like sadly eating a salad because she was saying, like, well, I can't taste anything. Might as well just eat a salad. That is really sad. Yeah. Well, how did Ruby discover smell training first?

Yeah. And how did that fall into her lap? Yeah, so she ended up going to see a doctor, an ear, nose and throat doctor, because she, this was like, you know, several weeks, I think maybe even a couple months at this point where her smell was not really coming back. So she saw a doctor near her in Houston, and he introduced her to smell training. So after that appointment, her boyfriend drove her strich to Whole Foods and they got. four bottles of essential oils. And she's been a small training ever since. And for Ruby, it seems to be working.

Her smell isn't back to 100%, but it's gotten much better. So today on the show, smell training. How practicing how to smell might help those who've lost their sense of smell. And why building back that sense takes time. I'm Emily Kwong, and this is Shortwave from NPR. Okay. The history of smell training is utterly bizarre, and you wrote about it in a really interesting way. Can you talk about maybe the first time in the 1980s, scientists maybe accidentally stumbled upon this?

Yeah, yeah. So there was a scientist who was studying a pig pheromone that's found in the swipe of male pigs. It's called Androstinone. And the scientist, he actually noticed after working with this lab for several years, that he was starting to pick up the scent of this. of this pig pheromone, that he had previously not been able to smell at all. You could tell which bottles had the pheromone and which bottles did not. And so this suggested to him that if you were exposed to a scent, that you could not smell, but you were continually exposed to it for a really long time,

it's possible you can train yourself to learn how to smell it and pick it out. But it's not really until scientists in 2009 that were studying people who could not who had lost her sense of smell really put this idea of smell training to like a rigorous standardly set protocols. Yeah, okay. So it sounds like you're saying, Sarah, with what happened in the 1980s,

that was almost by accident. Yeah. What changed to the point where smell training and the idea of it could be taken seriously and what did scientists figure out to standardize it as a protocol for people to recover their sense of smell? Yeah, yeah.

So you're right, as you're saying, that smell training as we know it, And it comes out of a 2009 study. So this is a German scientist named Thomas Hummel. He and his colleagues recruited 40 people who lost her sense of smell, either because of some kind of viral infection or because of a head injury, basically gave them a very standardized, like, day-by-day protocol about what to do. This is basically actually what Ruby was doing.

This is like almost the exact same protocol. This is the original. This is the... Yeah, this is the OG protocol. Okay. You take four essential oils. The classic ones are rose, lemon, eucalyptus, and the clove. And the idea is that these four smells kind of cover the range of possible smells and that they're piney and fruity and floral. So, you know, you're not picking like lemon and lime, which obviously are like very similar to each other.

The idea is to pick four that are, you know, pretty different from each other or different enough. So the volunteers for us to do this over a course of 12 weeks. And for twice a day, they would sniff these oils for 10 seconds each. Okay. Scientists use something called sniff and sticks. And it's literally just like pens that have like a standardized amount of smell in them. And you would wave them under someone's nose and see like whether they can detect it or not. Interesting.

So, okay. So Hummel and his fellow researchers, they invited the study participants to do this regimen. And then waving the sniff and stick under their nose, they could figure out over time if their sense of smell improved based on whether they were able to smell the same. sniff and stick. Yeah, exactly. But you know, it doesn't work for everyone, and it seems to work at different paces for different people. So it's not like a miracle drug. It's a very slow, very incremental process. And it can be really frustrating day to day, because, you know, from day one to day two, you're probably not going to notice a difference. So you might not even notice the difference from day one to day seven. It really could take three or four months. And Hummel and his colleagues also,

you know, tried to optimize this protocol. Would it be better if we added more, sense or more complex sense. So the essential oils are obviously just like one smell. What if you added like complex smells or combinations with smells? What if you switched out the sense after two months? So you did more smells or what if you had people look at a picture of what they were seeing when they were smelling. None of these really seemed to make the small training anymore effective. It seems like at the end of the day you just have to take the time to sniff these scents every day, of a period of many weeks. Smill training is just so fascinating to me

because what I'm hearing you say is that sniffing these four essential oils, rose, lemon, eucalyptus, and clove would rebuild your ability to smell things that aren't those scents. So how does learning how to smell other sense give you the ability to smell all sense?

Yeah, yeah, that's a great question. So let's think, I think a little bit about how smell works, right? Humans have about 400 distinct smell receptors. But we're able to distinguish between more than 400 smells, right? Like I think the current estimate is that humans can actually distinguish between like a trillion different smell. So, you know, when you're smelling like these four essential oils, you're not just stimulating four receptor neurons. You're probably stimulating olfactory neurons that are all across your refractory system.

So I think that that may be explaining why, like adding more smells, doesn't necessarily. seem to speed up smell training because it's not like a one-to-one relationship between a smell and a receptor and a neuron. There's actually a lot of overlap and redundancies in the whole system as well. That's so interesting. It also just sounds very mysterious to me. Yeah, I agree. It works, but we don't quite know how. Yeah. One way to think about smells like is its like bottom-up process. It's like molecule goes to your nose and it gets fed up. up to your factory bulb into your brain. But smell and like actually all of our senses is also very much a top down process, right? Like we smell things based on whether we pay attention to them,

right? That's what if you work in a factory or an office or even your house, you kind of don't really smell your house after a while, right? We stop paying attention to that. Or maybe you are really attuned to trying to smell a certain thing. Like if you're a smelly eight, you're always smelling wines all the time. You're really paying attention to what's in a wine. That can also really influence your sense of smell. So smell is in some ways also kind of subjective. It's not just receiving signals from the world. It's also your brain like deciding what to pay attention to. So with smell training being something that people are talking about more and practicing at home, what is the outlook for Ruby and for others who are in the process of recovering their sense of

smell or maybe haven't been able to recover their sense of smell at all. What is their future like? And how does that training play into it? Yeah, so small training definitely does. It seems to help a lot of people, but it helps different people to different degrees and, you know, at different paces and everybody kind of recovers some smell loss a little bit differently. But one of the things about COVID is that there's been so many people that people are finding themselves online. And I think losing your sense of smell can be very isolating because obviously no one can tell. You've lost that you just have to tell people about these weird sensory experiences you're having. But being able to talk to other people who've gone through the

same thing, I think has been really helpful for a lot of people. That was Sarah Zang, staff writer at the Atlantic. We've put a link to her full story on shortwave's page, which you can find at npr.org. This episode was produced by Thomas Liu. edited by Thomas Liu and Giselle Grayson and backtracked by Rasha Arendi. The audio engineer for this episode was Leo del Alguila. I'm Emily Kwong, and this is Shortwave, the Daily Science podcast from NPR. On NPR's Pop Culture Happy Hour podcast, we talk about movies, music, and more, like why the Great Pottery Throwdown is a comforting binge watch,

and a look back at some of Chadwick Boseman's essential performances. All of that, in around 20 minutes, every weekday. Listen now to the Pop Culture Happy Hour podcast from NPR.