The fifth sense
Once again, it’s that wonderful time when scientists everywhere hold their breath as the team opens the Outside/Inbox to answer listener questions about the natural world. Today’s theme is smell: how it works in the nose, the mind, and how much is still unknown about the fifth sense.
Question 1: Does it gross you out to know that every time you smell something, a little bit of that thing… is in your nose? What happens to the molecules we smell?
Question 2: Why do smells have such a powerful connection to memory?
Question 3: How do pheromones work in humans? Do ‘ideal mates’ really ‘smell better’ to us?
Question 4: Why does the smell of florals sometimes precede a migraine?
Question 5: What’s anosmia?
Featuring Rachel Herz, Bob Datta, Katie Boetang, and Tristram Wyatt, with thanks to Stephanie Hunter.
Outside/In seeks your questions for an upcoming Outside/Inbox
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You can send your questions to outsidein@nhpr.org or leave a voicemail on our hotline, 1-844-GO-OTTER.
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LINKS
Rachel Herz is the author of several books, including “Why You Eat What You Eat” and “The Scent of Desire.”
Nose and lips of Akhenaten, New Kingdom, Amarna Period, ca. 1353–1336 B.C. Found in Egypt. Public domain via Met Museum.
Tristram Wyatt is the author of “Pheromones and Animal Behavior.”
Katie Boetang hosts The Smell Podcast.
More on the connections between smell, memory, emotion, and health, featuring Bob Datta and Herz.
In the 1990s, one company claimed to have found human sex pheromones and tried to market them for use in perfumes.
Research on the connection between olfactory loss and depression, smell triggers for migraines, and an explanation of how COVID-19 causes loss of smell.
CREDITS
Outside/In host: Nate Hegyi
Reported, produced, and mixed by Justine Paradis, Catherine Hurley, and Felix Poon, with help from Marina Henke.
Editing by Taylor Quimby
Rebecca Lavoie is NHPR’s Director of On-Demand Audio
Music by Daniel Fridell, Caro Luna, Lofive, bomull, Jahzarr, Mindme, and John B. Lund.
Outside/In is a production of New Hampshire Public Radio
Thank you to all our listeners who sent in questions for this episode. We featured questions and feedback from Aubrey, Prudence, Faye, Jenna, Maria, and Shelby.
Audio Transcript
Note: Episodes of Outside/In are made as pieces of audio, and some context and nuance may be lost on the page. Transcripts are generated using a combination of speech recognition software and human transcribers, and may contain errors.
Justine Paradis: Oh, hello, Nate.
Nate Hegyi: Justine! Hello hello.
Justine Paradis: I recently heard about a really interesting experiment that I would like to share with you and this podcast. May I?
Nate Hegyi: Okay! Yes, I’m all ears.
Justine Paradis: Alright. So this experiment is about the suggestibility of perception, and specifically, our sense of smell. And it was conducted by someone named Rachel Herz.
Rachel Herz: So my name is Rachel Herz. I'm a neuroscientist, and I have been studying the psychological science of scent for over 30 years.
Justine Paradis: So what Rachel did, is she gathered a group of people to be her test subjects.
MUSIC: Del giorno, Daniel Fridell
Justine Paradis: And in the first session, she’d present them with five different smells. For each one, she’d give them a label for what they were smelling.
Rachel Herz: And in one case I present it to you and I say, this is parmesan cheese. And you go, oh yeah, I really like this. I would eat it, it's very familiar, etc., etc.
Justine Paradis: But then she brought the same participants back for a second session about a week later. She’d hand them a jar with the exact same scent. Except this time, she’d tell them the source of that smell was a different thing.
Rachel Herz: And now I say this is vomit. And people go, oh my God, it's disgusting. Of course I wouldn't eat it. It's really unpleasant. And I do not believe that this is the same scent that you gave me when you said it was parmesan cheese. And it is the exact same scent.
MUSIC SWELL AND FADE
Nate Hegyi: Okay, though to be fair, cheese rides the line, right? There are some extra stinky cheeses that you’re like, I kinda like this but it smells kinda like feet.
Justine Paradis: But is parmesan one of those cheeses?
Nate Hegyi: No, but I could also see, that there’s a definite, eh, you know, I’ve noticed a similarity.
Justine Paradis: She also did this with a violet leaf, saying it was either a fresh cucumber or mildew, and she also did it with incense vs. musty basement. The parmesan-vomit one was particularly strong though.
Nate Hegyi: I can still see both of these similarities, though. You know, like – I have a particularly sensitive sense of smell, and...
Justine Paradis: Really?
Nate Hegyi: Yes, and I will notice, if I smell something funky, you know, I have to get to the bottom of what it is, I’ll be like, this is a little TMI, is that my feet? Or is that like, cheese or something else like that?
Justine Paradis: Is that a delicious plate of cheese, yeah?
Nate Hegyi: Or is that a delicious plate of cheese? Like I can see these weird smells that overlap. I get it. I’m with the people that got tricked by the smells. I would definitely be in the same boat.
Justine Paradis: Well, what this shows is how psychological and how subjective and contextual our sense of smell is – how influenced by our brains and our experiences.
MUSIC: Para Charkiv (Instrumental Version), Caro Luna
Justine Paradis: But there’s a lot that we don’t understand about why it works. Because historically, research into the senses have been way more focused on vision.
Nate Hegyi: Which kind of makes sense, right? Vision has historically been considered the dominant sense for humans, right?
Justine Paradis: Well, a lot of research suggests that our brains devote more processing power to vision than other senses. But that’s starting to change, and as scientists are starting to learn more about our sense of smell, it opens up so many wonderful, complicated questions and insights about our brains.
MUSIC SWELL
Rachel Herz: it really does impact everything from our sense of self to our social relationships. Obviously relationship with food, our memories, our emotion, our sexual lives… everything.
Nate Hegyi: It’s once again that special time when scientists everywhere hold their breath as the Outside/In team opens up our mailbox and answers your questions about the natural world. This time around, we asked you to send in your questions about what’s known as the fifth sense: our sense of smell. And today, we’re answering some real stinkin’ good ones. I’m Nate Hegyi. Rifling through submissions with me is our producer Justine Paradis.
Justine Paradis: Yes, in fact, I tackled our first question of the day. This one was submitted by a friend of the show, Aubrey in Concord NH.
Aubrey: Does it gross you out a little bit to know that every time you smell a thing, a little bit of that thing is in your nose? And then my follow-up question is: once the molecules are in your nose, do they get absorbed? Where do they go?
Justine Paradis: Does it, Nate, gross you out that molecules of dog poo are in your nose?
Nate Hegyi: Yes, absolutely! I’ve seen this question and it has just stuck in my brain much like the dog poop is somehow stuck in my olfactory... It’s so gross.
Justine Paradis: You’re just haunted by this question, for months.
Nate Hegyi: I am, I am. But is it true?!
Justine Paradis: It is true, and there’s more to it, right?
Nate Hegyi: Okay.
Justine Paradis: Most of the chemicals we smell are volatile chemicals, and that just means chemicals that evaporate easily.
Nate Hegyi: Okay.
Justine Paradis: Unlike other mammals like mice or dogs, most of the human nose is devoted not to smell, but to breathing. So it warms and filters air before it gets to your lungs. To actually get to the point of detecting a smell –
Bob Datta: There's a long series of events that has to occur.
Justine Paradis: That’s neurobiologist Bob Datta, of the Harvard Medical School. Bob explained that the part that’s actually doing the smelling is deep in the nasal cavity. It’s way up and back, kind of at the level of your eyebrows. It’s called the olfactory bulb, and this is actually a bundle of nervous tissue.
Bob Datta: Inside our nose is a sheet of neurons. So, these are the same types of cells that live in your brain.
Justine Paradis: But these ones live outside the brain, much more exposed to the world. As protection, they’re covered in little hairs called cilia, plus a layer of mucus.
Bob Datta: And so anything you smell has to float through the air and then be dissolved in the mucus and then diffuse through the mucus and find its way to the tips of these neurons to the cilia.
Justine Paradis: So, a lot’s happening inside that mucus on the way to the neurons. Enzymes are in there metabolizing and changing the chemistry of the odors. And there are proteins too which –
Bob Datta: – kind of act to escort smells from the gas in your nose to the neurons that sense the odor in your nose… And only then do you sense the odor.
Justine Paradis: He also used the word “chaperone” here.
Nate Hegyi: Great. “Chaperone” is the perfect metaphor. Holding the odor’s nose and walking it towards the neurons.
Justine Paradis: Because they can’t be trusted on their own, you know. And so to answer Aubrey’s question: some of those molecules are getting “absorbed,” at least into the mucus. Others are destroyed, and still others get exhaled and never smelled at all.
Nate Hegyi: Okay.
Justine Paradis: I do want to share one more cool thing here. That little bundle of nerves inside your nose – they’ve got a kind of superpower. They’re so exposed to the world, to pollutants and smells and everything else, that they’re dying off all the time, but they’re also being regenerated by stem cells, which isn’t the case with any other neurons in your body.
Bob Datta: There's a lot of interest in this just to figure out whether we can't learn about how the nervous system might repair itself.
Justine Paradis: And so they might be important in ways that go well beyond smell.
Nate Hegyi: Very cool!
MUSIC: I Kinda Like it, LoFive
Justine Paradis: Nate, I’m wondering if you experience this same olfactory experience that I do: do people that you know and their houses have a specific smell?
Nate Hegyi: Yeah. For sure. Absolutely. I’m thinking of one of my friends’ houses. It’s a wonderful smell. I’ve always been jealous of the smell. I’ve been friends with them for a very long time. And no matter which house they move to, it smells the same. I don’t know what it is. But their house smells a way.
Justine Paradis: I don’t know what it is either. I think it’s beyond detergent or what people are cooking. That might mix in a little. But it’s nuts.
Nate Hegyi: It’s wild.
Justine Paradis: But it brings up how much we’re communicating through our sense of smell or what we smell like, that we might not even be aware of. And that brings us to our next question.
Nate Hegyi: Yes, we had our producer Felix Poon tackle this one. Hey Felix.
Felix Poon: Hey. So we got a question from Jenna in North Carolina.
Jenna: Do ideal mates really smell better to us as humans than non-ideal mates?
Felix Poon: Nate do you get the same Instagram ads I do for cologne that’s supposed to make me irresistible to the ladies?
Nate Hegyi: No, no that’s so fascinating. What kind of algorithm are you churning up?
Felix Poon: I don’t know, pheromone algorithms.
Nate Hegyi: Evidently.
Felix Poon: So, I followed my nose to Tristram Wyatt, he’s a zoologist at the University of Oxford. And I asked him, first of all, what the heck even is a pheromone?
Tristram Wyatt: So a pheromone is a molecule or combination of molecules that's the same in every male of a species or every female.
Felix Poon: So it’s basically a universal smell that’s supposed to elicit some universal response. And it’s been a lot easier to find in all sorts of animals and insects. The first one to be found was in silk moths in 1959.
Tristram Wyatt: A team had to collect the pheromone glands, the bits of tissue that produce the pheromones, from half a million moths.
Nate Hegyi: That sounds like a really tedious job.
Felix Poon: Yeah, they literally had to snip off the abdomens of half a million female moths and then isolate a molecule that, on its own, could attract male moths. This is actually something that’s used in pest control now, to basically divert moths instead of killing them.
Nate Hegyi: Okay so that’s moths, but what about pheromones in humans?
Felix Poon: Yeah it didn’t take long for scientists to go looking for sex pheromones in humans. And there was this famous study in the 1990s where a Swiss scientist tried testing for this in college students.
Tristram Wyatt: He got the male students to wear a t-shirt overnight, and then he had the female students sniff the t-shirt and rate it for whether they were attracted to the smell.
Felix Poon: And what he found was that the women preferred the t-shirts that were worn by men who were more genetically different from them.
Nate Hegyi: Well I guess that kind of makes sense because if you’ve got an older brother and you smell his t-shirt you’re like, ugh.
Felix Poon: Yeah, but it’s not really conclusive unless you isolate the specific molecule of attraction, like they did with the moths. Now there is one company that claimed to have found human sex pheromones in the 1990s. The one for males they said is called androstadienone, and the one for females they said is called estratetraenol.
Nate Hegyi: So these are the Instagram ads you’re getting now, it's from companies like this.
Felix Poon: Exactly. They infuse infused perfumes and colognes with these things. But, Tristram says there isn’t any evidence that these qualify as pheromones because they don’t elicit a universal response. The problem with trying to find human pheromones is that courtship is really complicated in humans. You know, there's personality, values, sense of humor. Which isn’t to say that smelling nice doesn’t affect attraction. I mean there are lots of studies on this and it definitely does have an impact. It’s just what smells nice to one person might smell stinky to another depending on say your culture or you know very subjective things.
Nate Hegyi: Right.
Felix Poon: But, Tristram’s still hopeful we’ll find human pheromones. A research team in France demonstrated that newborn babies will turn towards the smell of breast milk, and the breast milk doesn’t even have to be from their own mother. If they ever isolate the specific molecule that gets them to do that, then it would technically be the first pheromone discovered among humans. And…
Tristram Wyatt: Then that would give us much more confidence to put the hard work of looking for a human sex pheromone.
MUSIC: nyar, bomull
Nate Hegyi: Before we get to more of your smelly questions, we want to share some feedback y’all have given us. A few weeks ago, we put out an episode we called “The Potato Show.” And we asked you to send us your favorite ways to make potatoes. Shelby wrote in, sharing a method of serving baked potatoes served with tinned corned beef cooked with ketchup and pepper.
Justine Paradis: Yes, Shelby said, “I’m from Jamaica and I live in New York now. When I was younger I didn’t really like the budget meal of cornbeef with rice but now it’s delish and super quick to put together and reminds me of home. Having it with baked potato instead of rice also makes it 10x better.”
Nate Hegyi: Many of you told us you were moved by the episode, and specifically, Felix Poon’s story of how, after his mom’s cancer diagnosis, his dad took to making potato juice as a way to try and help. A listener named Faye sent us this voice memo.
Faye: I didn’t think I was listening to an emotional story about cancer and I almost cried on my run because of it… Felix’s story kind of hits all my nerves about growing up in Hong Kong. Those memories about Cantonese cooking shows, is so poignant and such a big part of my childhood, and I didn’t expect it from an outside show from New Hampshire.
Nate Hegyi: It’s really great to hear from you. Like it means a lot.
Justine Paradis: Yeah. This was a really nice and really – when you share personal things about your listening experience with us, we share it with the whole team, we talk about it –
Nate Hegyi: Yeah!
Justine Paradis: It was really nice to hear this one. So thank you so much Faye.
Nate Hegyi: It means a lot. Yeah. And please, our inbox, it is always open. The show’s email is outsidein@nhpr.org.
Faye: That is cool. That is all… So, keep up the good work.
BREAK
Nate Hegyi: Welcome back to Outside/In. I’m Nate Hegyi, here with our producer Justine Paradis, answering listener questions on the theme of smell.
Justine Paradis: Yup! Our next question comes from Amanda, who asked…
“Why do smells have such a powerful connection to memory?”
Justine Paradis: Nate, do you relate to this? Have you ever smelled something that sends you right back to childhood?
Nate Hegyi: Yes, the smell of diesel does. Specifically, diesel in a marina. It always brings me back to my childhood, going out with my uncle, off the coast of Vancouver Island, and going fishing. And it’s just a joyful memory.
Justine Paradis: For me it’s that super synthetic coconut-y smell of kids sunscreen.
Nate Hegyi: Right, that’s the amazing thing about smell. It’s just a direct blast, a direct vein right into your memory in a way that I think other senses don’t quite do.
Justine Paradis: Yeah, looking at a photo of ourselves as children on the beach – or out fishing with your uncle – that’s probably going be less vivid than smelling the diesel or the sunscreen.
Nate Hegyi: Right, yeah, exactly.
Justine Paradis: And that happens for a reason. So, here’s neuroscientist Rachel Herz.
Rachel Herz: When memories are triggered by scent, they are fundamentally, uniquely more emotional and evocative than when that same memory is triggered through any other mechanism.
Justine Paradis: The explanation for that is evolutionary. Our sense of smell is one of our older senses. And it’s deeply connected to older parts of the brain. Specifically, the hippocampus and the amygdala, so those are the memory and emotional centers of the brain. Neurobiologist Bob Datta said when you see something, that visual information is traveling through 10, maybe 15 or 20 neurons before it’s getting to the hippocampus.
Bob Datta: For smell, that number is two. So your olfactory system is basically hardwired into your memory and emotion systems directly.
Nate Hegyi: Which is why it feels like such a direct vein into your brain.
Justine Paradis: Direct nerve! It is!
Nate Hegyi: That’s really fascinating. It’s one of those rare moments where how I think about smell and memory is exactly how it works.
Justine Paradis: Yeah, it’s literally a fast short journey to the memory and emotional centers.
Nate Hegyi: That’s so cool.
Justine Paradis: So, Bob also told me there’s another significant connection between smell and memory. And that has to do with cognitive disorders: in fact, loss of your sense of smell is one of the first signs of Alzheimer's or Parkinson’s disease – so, if you’re middle-aged and you suddenly lose your sense of smell, Bob says:
Bob Datta: The odds that you will go on to develop Alzheimer's are something like ten times higher than if you had an intact sense of smell.
Nate Hegyi: That’s kind of frightening. Something to be aware of.
Justine Paradis: It’s something to pay attention to. Researchers don’t yet know if this is just a correlation or if there’s some causative thing going on here. Maybe the loss of a sense of smell is just revealing the condition of your nervous system, before other symptoms appear.
Nate Hegyi: Gotcha.
Justine Paradis: We don’t know. But a potential upside to this connection is: your nose offers a direct link to your nervous system, so maybe exercising our sense of smell can help exercise our brains.
Rachel Herz: Deliberate sniffing may be activating stem cells in the nostrils that then help with the regeneration of the sensory neurons that help in the recovery from that sort of physical end. But having the mental cognitive sort of energy also at the same time is helping the brain form those connections again and stimulating in the brain in a way that's effortful, which is good for brain function. So it’s always to sort of think, as it were!
Nate Hegyi: So literally stopping and smelling the roses.
Justine Paradis: Literally stopping and smelling the roses and thinking about it could actually be really, really good for you.
Nate Hegyi: That’s so cool.
MUSIC: Jahzarr, No Control
Justine Paradis: One of the first things I thought of when we came up with this theme of smell, Nate, was a question of my own about why some people (namely myself) – why are we so sensitive to certain scents? And even to the point of getting a headache from some scents. Do you experience this?
Nate Hegyi: I am very sensitive to certain smells. Not to the point of getting a headache, but I think my gross out factor. This is really sad, but when someone eats garlic, it’s took me a long time to figure out. I can smell garlic breath really strong.
Justine Paradis: Interesting.
Nate Hegyi: And, if you have an aversion to garlic breath, the solution? You yourself must eat garlic. And then it goes away.
Justine Paradis: Okay! Do you always carry around a stash?
Nate Hegyi: Yeah I always carry around a clove of garlic in my pocket, just to pop it in. But I don't get headaches or anything. But you do?
Justine Paradis: For me, it’s, yeah, synthetic scented candles or scented car ornaments especially. If I get in a cab abd there’s one hanging over the mirror, I know I’m gonna have a bad day. But even strong flowers like lilies or lilacs, they can trigger a migraine sometimes.
Nate Hegyi: So what’s the deal with that? Why does that happen?
Justine Paradis: We actually got a listener question about the mirror image of this phenomenon.
Prudence: Hi Outside/In team. My name is Prudence. I am calling from Pretoria in South Africa. And my question is related to migraines.
Justine Paradis: Prudence gets migraines from strong smells, just like I was describing earlier, but on top of that, she gets migraine with auras. Are you familiar with that term?
Nate Hegyi: I am familiar with the term aura but not when it comes to migraines. I’m guessing it’s different thing from what I’m thinking of.
Justine Paradis: Gotcha. An aura is a sensory disturbance which occurs before a migraine. But it’s often visual, like spots or flashes in your field of vision. But more rarely, it can be smell. Like smelling a phantom smell which isn’t there, which is what Prudence experiences.
Prudence: My aura scent is frangipani flowers. When I’m about to get a migraine, I start to smell frangipani flowers. Even if there are none around, I just get the scent in my nose, which leads me to my question which is: why does the smell of florals sometimes precede a migraine?
Justine Paradis: I asked two smell experts about why this happens to people like Prudence, and both of them basically said: we don’t know. Here again is neurobiologist Bob Datta.
Bob Datta: I think we don't really understand how chemical sensitivities interact with the olfactory system to cause changes in the brain. That is all emerging science.
Justine Paradis: So, Prudence, I am so sorry, unfortunately, this is one of those questions we actually cannot answer today, because the question touches on a lot of stuff we just don’t understand very well: migraines; why people are sensitive to certain smells, like gasoline, while others are soothing, like lavender, for instance. But Bob did tell me that smell auras are often also experienced by people with epilepsy.
Bob Datta: So, many epileptics, when they're about to get a seizure, get a smell aura. And that's just because of where in the brain the processing centers for smell are and the way in which they were organized.
Justine Paradis: So, if you are experiencing phantom smells or you’re hypersensitive to certain scents, it could be worth mentioning to your healthcare provider.
MUSIC: Blacklight, John B. Lund
Justine Paradis: So, a smell aura – hallucinating a smell that isn’t there – that’s called phantosmia. We also got a question about the inverse of phantosmia, which is something called anosmia.
MUSIC FADE
Maria: Hi, this is Maria Ordovas-Montanes. I’m from Massachusetts and I live in Oxford, England. Can you explain anosmia?
Nate Hegyi: So, we asked our intern Catherine Hurley to answer this one for us. Catherine jumped into a studio with our editor Taylor Quimby to talk it through.
Taylor Quimby: Anosmia is a really fun sounding word… and the only reason I've ever heard of it is because of Covid-19.
Catherine Hurley: I think that's when a lot of people heard about it for the first time.
Taylor Quimby: Yeah.
Catherine Hurley: Anosmia is basically the inability to smell odors. It affects about 3% of Americans. And just like eyesight or hearing, it can range from partial to full loss of smell.
Taylor Quimby: And sometimes it's just a few days and sometimes it's a lot longer?
Catherine Hurley: That's correct. Some people are born with anosmia, but others acquire it later in life after a viral respiratory illness. One of them is Katie Boateng, who I called up last week. She's president of the Smell and Taste Association of North America and host of the Smell Podcast.
Katie Boateng: For me, it was definitely an absolutely a loss. I was 19 years old at the time. It was devastating, and it had a lot of repercussions on my personal life, including like nutrition and mental health.
Taylor Quimby: I bet.
Catherine Hurley: Katie developed anosmia after getting sick her freshman year of college.
Katie: For like five or six weeks. It was a really lingering sickness. When I was sick, I realized that I wasn't like smelling or tasting my food the same way as usual. But that happens when you're sick, right? Everyone knows that. What I didn't know is that it could be permanent.
Taylor Quimby: I don't think I would want to lose my sense of smell.
Catherine Hurley: I think that is pretty common, when people are asked which of the five senses they would want to give up, I think smell might be the first that comes to mind, but the people who have lost it… that might not be their first choice.
Taylor Quimby: Yes.
Catherine Hurley: But there are other things that can cause anosmia, too. Traumatic brain injuries, damage to the olfactory nerve and straight up aging. And, you know, a lot of people don't realize how much they take smell for granted until it's gone. First of all, smell is a really important factor in taste. That's a given.
Taylor Quimby: Yeah, that's the one that everybody kind of knows.
Catherine Hurley: But smells also trigger memories and emotions and it can be really hard to go without that. And another factor is safety.
Katie: So for example, if there is a gas leak in your home or if there's a fire and there's smoke in your home, you don't have the ability to know that that's happening based on your sense of smell.
Taylor Quimby: I can imagine even just like, you know, like smelling food in your fridge to see if it's still good.
Catherine Hurley: Or, yeah, food going bad, like you can't really tell what other people are smelling around you. And there's a mental health toll to all of this. Research shows a link between olfactory dysfunction and depression, and in one study, participants described feeling isolated, disconnected, and insecure because of their anosmia.
Taylor Quimby: Is it considered a disability, like officially?
Catherine Hurley: Not under the ADA. But to many people, like Katie, it's considered an invisible disability.
Katie: I absolutely believe that it is a disability. A disability is defined as something that inhibits your ability to live your daily life. And so without your sense of smell, you're absolutely affected.
Taylor Quimby: So talk to me about treatment. Because for Covid-19, it seemed like you basically just had to wait for it to come back.
Catherine Hurley: Well, to learn more about treatment, I spoke with Stephanie Hunter. She's a fellow at the Monell Chemical Senses Center. She said an option for some people is smell training, where you regularly inhale the scent of rose, eucalyptus, lemon and clove, which is all in an effort to regain your sense.
Taylor Quimby: Just like, huff it?
Catherine Hurley: Smell it regularly for a couple minutes, twice a day, for I believe it's at least three months. So it's pretty regimented with those scents. Yeah, but the effectiveness of smell training varies, and Stephanie says there just aren't very good treatments right now. But one thing that is getting better is diagnosis. Sense of smell can say a lot about your health, and Stephanie was part of a team that developed a rapid smell test to use at your yearly physical, just like you'd get tested for vision or hearing.
Taylor Quimby: I actually have a physical on Friday.
Catherine Hurley: So maybe they'll take out the smell test.
Taylor Quimby: I hope so.
MUSIC: Go to Hell (Instrumental Version), Mindme
Nate Hegyi: So this kind of begs the question, Justine, did you ask your smell scientists if they’ve learned why some people lose their sense of smell with COVID?
Justine Paradis: I did! Neurobiologist Bob Datta said that they do now have at least a partial understanding.
Nate Hegyi: Okay.
Justine Paradis: He said the virus attacks the support cells that help the neurons to work. And the length of time that the sense of smell is damaged can really vary because the virus can also attack the stem cells in your nose.
Bob Datta: So it's kind of a double whammy. Like you lose the support cells and you lose the stem cells that are the ones that are going to do the fixing. And so that that can mean that it takes a long time for the epithelium to rebuild itself.
Justine Paradis: But Bob also said that there are many cases where people who had lost their sense of smell for a year or even years, who have gained it back.
Bob Datta: And so for those who are listening, who, you know, maybe got Covid and still don’t have their sense of smell back, there actually is no evidence that that's truly permanent. Um, you know, I can't promise that it will recover, but we're still, we're still learning.
Justine Paradis: And one thing that’s happened partly as a result of the COVID-19 pandemic, is the launch of a new National Smell and Taste Center at the National Institute of Health. So, hopefully, a lot more attention and research on these topics are on its way.
Nate Hegyi: At that launch, they better have had some really tasty hors d'oeuvres and some really smelly cheeses.
Justine Paradis: You’d have to. Is there any other way?
Nate Hegyi: Exactly.
MUSIC: Para Charkiv (Instrumental version), Caro Luna
Justine Paradis: Before we go – maybe we should announce the theme for our next Outside/Inbox questions?
Nate Hegyi: Yes, yes we should. The news cycle, it is dominated by the US presidential election right now. But we want to know what questions about politics, about the election, that maybe Outside/In could look into for you. What do you want to know about what this election means for climate change or environmental regulation? Maybe you’ve got questions about Project 2025, that’s been in the news a lot lately. Or maybe you’re curious about presidential transitions more generally – like how do specific agencies plan for a new administration, like national parks or the EPA?
Justine Paradis: Our favorite way to get questions is when you send us a recording of yourself asking the question. You can send that to our email, which is outsidein@nhpr.org.
Nate Hegyi: But you can also call our hotline and leave a voicemail. Our number is 1-844-GO-OTTER.
Justine Paradis: All this info will be in the show notes as well.
Nate Hegyi: And that’s it for Outside/In this week. This episode was produced and reported by Justine Paradis, Catherine Hurley, and Felix Poon. It was edited by Taylor Quimby. NHPR’s director of podcasts is Rebecca Lavoie.
Justine Paradis: Music in this episode came from Daniel Fridell, Caro Luna, Lofive, bomull, Jahzarr, Mindme, and John B. Lund.
Nate Hegyi: Outside/In is a production of NHPR.
Nate Hegyi: What do you think NHPR smells like?
Justine Paradis: I know what it smells like.
Nate Hegyi: I know what it smells like too. Sterile office. That’s what it smells like.
Justine Paradis: Sterile office. Yes, the sterile office smell. Is that a spray?