WEBVTT - Is Itching Contagious? (and does scratching actually help?) 0:00:03.160 --> 0:00:06.519 You're listening to Part Time Genius, the production of Kaleidoscope 0:00:06.720 --> 0:00:14.320 and iHeartRadio. Guess what Will, What's that Mango? I was 0:00:14.400 --> 0:00:17.840 looking through the Ignoble Prizes, which released this week, and 0:00:18.160 --> 0:00:21.000 for those who don't know, these are funny prizes that 0:00:21.200 --> 0:00:23.920 honor academic papers that are so surprising that they make 0:00:23.960 --> 0:00:26.599 people laugh and then think. And one of the articles 0:00:26.600 --> 0:00:28.680 that caught my attention was a Peace Prize that they 0:00:28.720 --> 0:00:32.240 gave out for studying the pleasure ability of scratching an itch. 0:00:32.760 --> 0:00:35.040 I do love that they gave out a Peace prize 0:00:35.080 --> 0:00:37.839 for this, but like, what did the scientists actually find 0:00:37.880 --> 0:00:38.600 in a study? 0:00:39.040 --> 0:00:41.920 So apparently they were looking into when you itch, what 0:00:42.200 --> 0:00:45.320 areas that you can scratch our most satisfying. So they 0:00:45.360 --> 0:00:47.840 looked at a few areas and triggered scratching in people 0:00:47.840 --> 0:00:49.960 in those places, and they came to the conclusion that 0:00:50.000 --> 0:00:53.720 the places where a little scratching is most satisfying is 0:00:53.760 --> 0:00:54.360 on your back. 0:00:54.520 --> 0:00:57.400 Mm hmm. I could have guessed that a backscratch obviously 0:00:57.480 --> 0:00:58.480 feels amazing. 0:00:58.720 --> 0:01:00.800 But the other place of high pleasure your ability was 0:01:00.840 --> 0:01:03.520 the ankle. If you get a mosquito bite, for instance, 0:01:03.560 --> 0:01:07.000 on your ankle, scratching it results in the most satisfaction, 0:01:07.319 --> 0:01:10.680 and apparently the higher the scratch on your foot, like 0:01:10.720 --> 0:01:13.199 the closer it is to the ankle, the more satisfying 0:01:13.240 --> 0:01:13.520 it is. 0:01:14.280 --> 0:01:16.679 You know, I think if you had asked me, like 0:01:16.800 --> 0:01:19.120 where the most pleasurable place to scratch an itch was, 0:01:19.160 --> 0:01:22.240 the ankle might have been tenth on my list. But 0:01:22.319 --> 0:01:24.160 now that you're saying it, and especially when you say 0:01:24.200 --> 0:01:27.440 mosquito bite, I actually sort of get it. It makes sense. 0:01:28.000 --> 0:01:29.840 Yeah, well, I'm so lucky it enough to quiz you 0:01:29.880 --> 0:01:30.679 on all the other. 0:01:30.600 --> 0:01:33.160 Places that you I can name the others, actually I'll 0:01:33.160 --> 0:01:34.520 put to I'll email you a list. 0:01:35.040 --> 0:01:38.120 But all this reading about itching and scratching made you 0:01:38.120 --> 0:01:40.640 want to look into the science of itches, like why 0:01:40.680 --> 0:01:43.440 do we itch? Why does it feel so good to scratch? 0:01:43.520 --> 0:01:45.560 And what's our body trying to tell us from all 0:01:45.600 --> 0:01:47.080 of this? So let's dive in. 0:02:05.840 --> 0:02:11.120 Hey, their podcast listeners, welcome to Part Time Genius. I'm 0:02:11.120 --> 0:02:13.320 Will Pearson and as always I'm joined by my good 0:02:13.320 --> 0:02:16.520 pal Mangas shot Ticketerter and sitting behind that big booth, 0:02:16.520 --> 0:02:19.880 and he's always up to something interesting. This week, he's 0:02:19.919 --> 0:02:22.560 got a whole bunch of posters behind him, and actually 0:02:22.880 --> 0:02:26.720 these appeared to be homemade but very professional posters behind him, 0:02:27.000 --> 0:02:29.760 one of them of Itchy and Scratchy from The Simpsons, 0:02:30.240 --> 0:02:33.679 one of them the character poison Ivy from Batman. Sorry, 0:02:33.720 --> 0:02:35.919 that one took me a minute. And then I think 0:02:36.000 --> 0:02:38.720 that's a poster of the musician Lee scratch Perry. 0:02:38.840 --> 0:02:41.400 Is that the okay? All right? 0:02:41.480 --> 0:02:44.920 All because we are doing an episode on itching, So 0:02:45.040 --> 0:02:48.400 well done, Dylan. That's our wonderful producer, Dylan Fagin. 0:02:48.680 --> 0:02:51.200 Actually, you know, before we start talking about this, I 0:02:51.240 --> 0:02:53.760 love that he's got that Itchy and Scratchy poster up there. 0:02:53.919 --> 0:02:56.800 And I read this thing about how sometimes the Simpson 0:02:56.840 --> 0:03:00.440 writers used to use the Itchy and Scratchy cart tune 0:03:00.880 --> 0:03:04.000 just for inside jokes. And there's this one episode where 0:03:04.040 --> 0:03:06.639 the writers added a character called Puuci to the mix, 0:03:06.720 --> 0:03:09.399 so it was like Itchy and Scratchy and Poucy because 0:03:09.720 --> 0:03:13.160 apparently a focus group had recommended that they add another character, 0:03:13.240 --> 0:03:15.240 and the whole show ends up being a disaster. But 0:03:15.639 --> 0:03:18.120 what I didn't realize was that it was basically making 0:03:18.160 --> 0:03:20.240 fun of the fact that I think this was in 0:03:20.280 --> 0:03:23.959 the eighth season. The execs at Fox asked the Simpsons 0:03:24.040 --> 0:03:27.240 writers to add a teenager to the family because they 0:03:27.320 --> 0:03:30.400 thought it would I guess make the show more lively 0:03:30.520 --> 0:03:34.480 or something. And the Simpsons writers refused, but they decided 0:03:34.520 --> 0:03:36.920 to mock it on the show in Itchy and Scratchy, 0:03:36.960 --> 0:03:37.640 which I just think it. 0:03:39.960 --> 0:03:40.520 So fun. 0:03:40.760 --> 0:03:42.720 Anyway, I had to throw that tangent in there. But 0:03:42.920 --> 0:03:44.280 let's get started, all right. 0:03:44.320 --> 0:03:45.840 Well, one of the things that I wanted to look 0:03:45.880 --> 0:03:49.120 into is why we say we're itching to do something, 0:03:49.200 --> 0:03:51.960 like when we're eager to do something, and it actually 0:03:51.960 --> 0:03:55.040 comes back to Latin so weirdly, on our skin, we 0:03:55.120 --> 0:03:58.280 have these special itch sensing nerve endings and when they 0:03:58.280 --> 0:04:01.800 get stimulated, this is whether it's by mechanical, thermal, or 0:04:01.880 --> 0:04:06.320 chemical mediators, we get an itching sensation. So those nerve 0:04:06.440 --> 0:04:09.520 endings are called pre receptors. And in fact, the scientific 0:04:09.600 --> 0:04:12.160 word for itching is proitis. 0:04:12.400 --> 0:04:14.360 I actually love when the scientific words for things are 0:04:14.400 --> 0:04:18.880 so different, Like apparently the scientific word for burping is eructation. 0:04:19.920 --> 0:04:20.400 Is it? Really? 0:04:20.600 --> 0:04:21.720 I did not know that? 0:04:22.279 --> 0:04:25.080 So tell me a little bit about proritis. 0:04:25.160 --> 0:04:28.440 All right. Well, Proitis comes from the Latin word periray, 0:04:28.560 --> 0:04:31.560 which means to itch or to long for it's hard 0:04:31.560 --> 0:04:32.880 to say, but that's what it means. 0:04:33.400 --> 0:04:35.960 So the idea of longing and desire is linked with 0:04:36.080 --> 0:04:38.080 this physical sensation of itching. 0:04:38.640 --> 0:04:40.880 Yeah, that's exactly right. And you know it makes sense 0:04:40.920 --> 0:04:42.880 because when you have an itch, you feel like you 0:04:43.120 --> 0:04:46.400 have to scratch it. Actually, the first recorded definition of 0:04:46.400 --> 0:04:50.000 an itch came from a German physician named Samuel Hoffenreffer 0:04:50.440 --> 0:04:53.960 back in sixteen sixty. So he defined an itch as quote, 0:04:54.120 --> 0:04:58.400 any unpleasant sensation that elicits the desire or reflex to 0:04:58.640 --> 0:05:01.960 scratch or put another If you're scratching something, then the 0:05:02.040 --> 0:05:05.560 sensation that provoked it is, by definition an itch. 0:05:06.040 --> 0:05:08.320 Can you talk about that itch pain relationship a little more? 0:05:08.480 --> 0:05:12.359 Mm hmm. There's a complex relationship between itching and pain. 0:05:12.640 --> 0:05:15.280 The pure receptors I mentioned before are on the end 0:05:15.279 --> 0:05:18.640 of specialized nerve cells called sea fibers, and these sea 0:05:18.640 --> 0:05:22.360 fibers are identical to those associated with the sensation of pain, 0:05:22.960 --> 0:05:25.440 but they are functionally different because they only convey the 0:05:25.480 --> 0:05:28.520 itch sensation. So when they're stimulated on the skin, these 0:05:28.520 --> 0:05:31.599 sea fibers carry signals along the nerve to the spinal 0:05:31.680 --> 0:05:34.479 cord and onto the brain of course, and that's where 0:05:34.480 --> 0:05:38.640 they're processed and that generates this scratching or rubbing reflex 0:05:38.720 --> 0:05:39.760 response to that itch. 0:05:40.440 --> 0:05:42.520 But why is our reflex to scratch it? 0:05:43.040 --> 0:05:46.360 Well, scratching it interferes with the sensations arising from these 0:05:46.400 --> 0:05:49.120 pure receptors, And this is the interesting part. They do 0:05:49.160 --> 0:05:53.080 this by stimulating various pain receptors in the same areas, 0:05:53.360 --> 0:05:56.440 so the pain is almost like a save for the itching. 0:05:56.520 --> 0:05:58.919 And you know, it's not just scratching that will stop 0:05:58.960 --> 0:06:02.680 an itch, like other pain full stuff like heat or capsation. 0:06:02.800 --> 0:06:05.640 Of course, the hot stuff and peppers or even electrical 0:06:05.680 --> 0:06:07.720 shocks can stop itching. I don't know that you'd want 0:06:07.760 --> 0:06:10.200 to take it to that length, but turns out that 0:06:10.279 --> 0:06:13.039 does work. But you know, pain can stop an itch. 0:06:13.080 --> 0:06:16.640 But it's unclear whether the pain and itching are separate 0:06:16.680 --> 0:06:20.520 sensations or like the same sensation. But I don't know, 0:06:20.640 --> 0:06:21.159 just less. 0:06:21.320 --> 0:06:23.240 Can you talk about that relationship a little more. 0:06:23.320 --> 0:06:26.920 There's basically two theories about how this works. So there's 0:06:26.960 --> 0:06:31.240 the intensity theory and the specificity theory. So the intensity 0:06:31.279 --> 0:06:34.200 theory states that the skin is studded with this array 0:06:34.240 --> 0:06:38.200 of nerve endings called no susceptors. Now, their job is 0:06:38.240 --> 0:06:42.120 to relay information about the presence of potentially damaging stimuli 0:06:42.200 --> 0:06:44.640 to the spinal cord and the brain, and so a 0:06:44.640 --> 0:06:47.960 weak assault on these neurons result in an itch, while 0:06:47.960 --> 0:06:50.719 a fully fledged attack results in pain. 0:06:51.279 --> 0:06:54.240 So, like you said, the same sensation but less. 0:06:54.360 --> 0:06:56.640 I nailed it, and I'm glad you understand it now. 0:06:56.680 --> 0:06:59.679 But you know, the specificity theory states that some neurons 0:06:59.680 --> 0:07:03.040 are responsible for pain while a different set cares about 0:07:03.080 --> 0:07:06.560 an itch. Or alternatively, it could be that there's a 0:07:06.680 --> 0:07:09.960 single set of neurons responsible for no susception, but that 0:07:10.040 --> 0:07:13.360 they somehow tell the difference between stimuli that are itchy 0:07:13.480 --> 0:07:15.440 and those that hurt. 0:07:15.640 --> 0:07:18.360 But you would never scratch something that's just hurting you, right, 0:07:18.400 --> 0:07:20.720 Like you don't stub your toe and then scratch at 0:07:20.720 --> 0:07:21.520 it to stop. 0:07:21.240 --> 0:07:24.480 The pain, right, I mean, there are distinct sensations that 0:07:24.520 --> 0:07:28.400 elicit these very distinct reactions. So when something hurts, our 0:07:28.400 --> 0:07:31.960 body responds, you know, with their withdrawal reflex. But you know, 0:07:31.960 --> 0:07:33.720 think about it. You put your hand over a fire, 0:07:33.840 --> 0:07:36.720 the pain makes you yank it back, but the scratching 0:07:36.760 --> 0:07:41.520 reflex brings attention toward rather than away from, the affected skin. 0:07:42.080 --> 0:07:44.600 And you know this is probably evolutionary, like if you're 0:07:44.600 --> 0:07:47.560 looking closer at a quick scratch, or even just mindlessly 0:07:47.600 --> 0:07:51.280 scratching at something, it's pretty effective at removing an insect 0:07:51.400 --> 0:07:53.920 or other unwanted material from your skin or your hair. 0:07:54.000 --> 0:07:55.080 So it actually works. 0:07:55.320 --> 0:07:59.000 Yeah, that's interesting about a scratch drawing attention to your 0:07:59.160 --> 0:08:00.680 skin or your body. 0:08:00.800 --> 0:08:03.960 Yeah, And so here's how it works. Like, when something 0:08:04.000 --> 0:08:07.360 bothers the skin, like a mosquito bite, the cells release 0:08:07.400 --> 0:08:10.920 a chemical, usually a histamine, as an immune response to this, 0:08:11.480 --> 0:08:14.080 and that release provokes the no susceptors in the skin 0:08:14.120 --> 0:08:17.120 to send a message to the spine, which then relays 0:08:17.120 --> 0:08:20.440 the message through a bundle of nerves called the spinathalmic 0:08:20.640 --> 0:08:23.240 tract all the way up to the brain. So, in 0:08:23.240 --> 0:08:25.400 two thousand and nine, this group of researchers use the 0:08:25.480 --> 0:08:28.480 histamine injection to make the legs of their non human 0:08:28.600 --> 0:08:33.600 primates itch while an electrode monitored what happened inside those tracks. 0:08:34.000 --> 0:08:37.199 And as soon as the histamine was injected, the neurons 0:08:37.200 --> 0:08:40.679 started firing faster. So when the researchers offered up a 0:08:40.720 --> 0:08:44.000 few scratches, those neurons slowed their fire. And what those 0:08:44.040 --> 0:08:47.000 electrodes showed them was that the scratching actually does its 0:08:47.000 --> 0:08:49.079 work in the spinal cord rather than the brain. 0:08:49.920 --> 0:08:52.080 So I'm actually glad that you brought up that spine 0:08:52.120 --> 0:08:54.760 itch connection because I saw something about that in my 0:08:54.920 --> 0:08:57.120 research and decided to look into it a little more. 0:08:57.160 --> 0:09:13.600 But before we get into that, let's take a quick break. 0:09:14.640 --> 0:09:16.880 Welcome back to Part Time Genius, where we're talking all 0:09:17.000 --> 0:09:20.079 things itchy. So, Mango, you were just about to talk 0:09:20.080 --> 0:09:22.800 about the connection between the spine and itches. 0:09:23.320 --> 0:09:26.079 Yeah, So this discovery comes from two thousand and seven, 0:09:26.160 --> 0:09:29.679 when a professor and researcher named Jufeng Chen at the 0:09:29.720 --> 0:09:32.680 Washington University School of Medicine led a team that was 0:09:32.720 --> 0:09:36.360 looking into the role of a specific receptor called GRPR. 0:09:36.559 --> 0:09:39.760 It's the gastrin releasing peptide receptor, and he was trying 0:09:39.800 --> 0:09:42.560 to figure out what it had to do with itching. Now, 0:09:42.800 --> 0:09:45.560 no one had really studied itch as separate from pain 0:09:45.720 --> 0:09:48.400 before two thousand and seven, but Chen and his team 0:09:48.440 --> 0:09:51.240 were looking at mice that were missing the GRPR gene 0:09:51.240 --> 0:09:54.120 to see if they reacted differently to pain stimuli than 0:09:54.200 --> 0:09:57.280 normal mice did. And while they didn't react any differently 0:09:57.320 --> 0:10:01.120 to pain when they stimulated the GRPR, normal mice. The 0:10:01.160 --> 0:10:03.880 mice starts scratching themselves as if they had this really 0:10:03.920 --> 0:10:06.760 bad itch, and that's how they figured out that the 0:10:06.800 --> 0:10:10.560 pain sensation and the itch sensation are mediated by separate 0:10:10.600 --> 0:10:14.160 sets of genes in the spinal cord, which means potentially 0:10:14.240 --> 0:10:16.800 that drugs can actually be used to suppress the itch 0:10:16.840 --> 0:10:21.600 sensation without affecting the pain sensation. And that's particularly important 0:10:21.640 --> 0:10:24.520 because pain can be kind of this like protective queue 0:10:24.640 --> 0:10:27.640 that warns of danger. So it'd be great to have 0:10:27.720 --> 0:10:30.920 this anti itch medication that doesn't compromise our pain sense 0:10:30.960 --> 0:10:31.720 and capability. 0:10:32.320 --> 0:10:34.000 Yeah, I mean that makes sense. It's best to be 0:10:34.160 --> 0:10:36.200 less itchy and safe ideally. 0:10:36.760 --> 0:10:39.640 Yeah, but Chen didn't stop there. So ten years later, 0:10:39.679 --> 0:10:44.640 in twenty seventeen, his teammate another really interesting discovery about itchiness. 0:10:45.200 --> 0:10:47.840 I keep itching, just talking about itching. It's almost like 0:10:47.840 --> 0:10:49.760 when you're in a place and you're not supposed to laugh, 0:10:49.800 --> 0:10:51.560 and then you can't help but laugh. That that is 0:10:51.600 --> 0:10:53.480 the experience I'm having. I don't know about. 0:10:53.200 --> 0:10:59.120 Youah, yeah, totally. I want to scratch my head so badly, right, yeah, 0:10:59.160 --> 0:11:02.360 And it's funny because us, you know, his team actually 0:11:02.440 --> 0:11:05.640 was the ones that discovered that itchiness is contagious. So 0:11:06.120 --> 0:11:08.760 they did this experiment with two different groups of mice. 0:11:08.920 --> 0:11:11.320 And I'm not sure why it's always mice. It's never 0:11:11.360 --> 0:11:13.800 like a group of frat guys who lives in Williamsburg. 0:11:13.960 --> 0:11:16.760 But the researchers bred one group of mice to be 0:11:16.840 --> 0:11:19.480 chronically itchy, and then they put the itchy mice in 0:11:19.520 --> 0:11:22.520 a cage next to normal mice, and then they recorded 0:11:22.600 --> 0:11:25.000 hours and hours of both sets of mice, and when 0:11:25.000 --> 0:11:28.120 they analyzed the footage, they discovered that the normal mice, 0:11:28.360 --> 0:11:32.240 just by observing the chronically itchy mice scratching, scratched themselves 0:11:32.240 --> 0:11:35.760 twice as much. Basically, the normal mice became twice as itchy. 0:11:36.480 --> 0:11:39.520 Imagine what fund we could have making other people scratch themselves, 0:11:39.520 --> 0:11:41.600 Mango like, All we have to do is stand around 0:11:41.679 --> 0:11:44.160 them for hours scratching ourselves. 0:11:44.600 --> 0:11:47.280 It sounds like a really good use of time. But 0:11:47.720 --> 0:11:49.840 it turns out there are other ways to get people 0:11:49.840 --> 0:11:53.200 to itch too. So in nineteen ninety nine, German researchers 0:11:53.240 --> 0:11:55.800 found that just listening to a lecture about itching made 0:11:55.800 --> 0:11:58.760 the audience itch and start to scratch themselves. And the 0:11:58.800 --> 0:12:02.080 aim of the lecturers is to present an itch inducing lectures. 0:12:02.080 --> 0:12:05.000 So they showed all these slides that induce scratching, right, 0:12:05.080 --> 0:12:09.000 like pictures of fleas mites, allergic reactions. Then they showed 0:12:09.080 --> 0:12:12.439 slides that induced relaxation and a sense of well being. 0:12:12.480 --> 0:12:15.679 So they showed like pictures of baby skin and soft 0:12:15.800 --> 0:12:18.320 down and a mother with a child in her arms, 0:12:18.320 --> 0:12:21.720 and they discovered a few fascinating things. So first the 0:12:21.760 --> 0:12:26.360 self reported itch sensation and all this observed scratching increased 0:12:26.360 --> 0:12:29.839 after they showed those first set of pictures. But after 0:12:29.880 --> 0:12:32.400 hearing the lectures, discussed the next set of things and 0:12:32.480 --> 0:12:36.920 showing those other pictures, the observed scratching decreased. So you 0:12:36.920 --> 0:12:40.360 can actually lower the itch sensation when you show calm 0:12:40.520 --> 0:12:41.520 soothing pictures. 0:12:42.120 --> 0:12:44.960 I've never really thought about it, like working in reverse, 0:12:45.000 --> 0:12:47.600 So you could potentially soothe an itch by looking at 0:12:47.720 --> 0:12:48.680 calming images. 0:12:49.400 --> 0:12:51.800 Yeah, but I guess the question is like, would you 0:12:51.840 --> 0:12:52.400 want to do that? 0:12:53.440 --> 0:12:54.000 What do you mean? 0:12:54.720 --> 0:12:58.480 So? I mean, itch remedies are great, but sometimes itching 0:12:58.559 --> 0:13:02.319 is medically necessary, right, and sometimes isn't the best feeling 0:13:02.360 --> 0:13:04.920 of the world, like a really good backscratch. I mean, 0:13:05.280 --> 0:13:07.840 people have been talking about this forever. In a nineteen 0:13:07.880 --> 0:13:11.240 forty eight paper in the Journal of Investigative Dermatology. This 0:13:11.360 --> 0:13:15.360 neurophysiologist George Bishop wrote, quote, scratching an itch with a 0:13:15.440 --> 0:13:18.880 violence that would cause pain elsewhere maybe experienced as one 0:13:18.920 --> 0:13:22.880 of the most exquisite pleasures. And the poet Ogden Nash 0:13:22.920 --> 0:13:26.520 once said, quote, happiness is having a scratch for every itch. 0:13:27.600 --> 0:13:29.480 I mean, that's definitely true. But you know, like the 0:13:29.520 --> 0:13:33.120 pleasure and pain cocktail of an itch is, it's pretty complicated. 0:13:33.480 --> 0:13:36.080 Like patients with exema have reported that they scratch not 0:13:36.200 --> 0:13:39.560 until the itch has subsided, but until it no longer 0:13:39.640 --> 0:13:42.080 feels good to scratch, So it's a little different. 0:13:42.440 --> 0:13:44.800 Yeah, that makes sense, although it seems like, you know, 0:13:44.920 --> 0:13:47.559 that could exacerbate the skin conditions. 0:13:47.200 --> 0:13:50.280 Right, Yeah, not only that, but chronic itching can cause 0:13:50.320 --> 0:13:53.520 psychological distress, and this is something we really don't think 0:13:53.520 --> 0:13:56.520 about that much, but there's a stigma associated with skin 0:13:56.640 --> 0:14:00.600 disorders and scratching. So one study interviewed adults with chronic 0:14:00.679 --> 0:14:03.640 itching conditions, and almost all of them said that itching 0:14:03.679 --> 0:14:08.160 had profound emotional effects, such as depression or guilt or 0:14:08.200 --> 0:14:12.200 panic and you know, sometimes feeling isolated because the resulting 0:14:12.240 --> 0:14:16.520 scratching elicited such negative responses. From other people, and it 0:14:16.600 --> 0:14:20.320 might even have historical roots, like in early European medical practices, 0:14:20.640 --> 0:14:23.560 and itch wasn't just equated with an effectious disease. It 0:14:23.640 --> 0:14:27.200 also conveyed these moral lapses, like like a lack of 0:14:27.280 --> 0:14:30.240 hygiene or social inferiority. So there was a lot wrapped 0:14:30.320 --> 0:14:30.680 up in it. 0:14:31.400 --> 0:14:33.440 Yeah, that makes a lot of sense about the social 0:14:33.520 --> 0:14:35.840 history that you know. I this just reminded me of 0:14:35.840 --> 0:14:38.400 a story when Henry was like three years old. We 0:14:38.560 --> 0:14:41.640 had this couple over to our house for dinner, and 0:14:41.720 --> 0:14:44.080 we were all sitting downstairs and we put Henry to bed, 0:14:44.480 --> 0:14:46.800 or we thought we'd put Henry to bed, and then 0:14:46.920 --> 0:14:50.760 like he walks down completely naked. He's like years old, 0:14:50.840 --> 0:14:55.960 and he goes, guys, I got examat. Oh no, I 0:14:56.000 --> 0:14:58.120 don't even know how we learned the word examon and 0:14:58.200 --> 0:15:01.560 where his clothes were, but it was Yeah. 0:15:00.920 --> 0:15:03.200 So like, weirdly that sort of thing is not socially 0:15:03.240 --> 0:15:05.920 acceptable to just walk into a room naked and announce that. 0:15:06.120 --> 0:15:08.920 So it's just I see what we're talking about here. 0:15:08.920 --> 0:15:12.840 But I mean, you know it, you think back to 0:15:12.880 --> 0:15:17.480 when humans learn to associate certain things with disease, like 0:15:18.440 --> 0:15:20.600 around scratching, or as we're talking about here, that can 0:15:20.640 --> 0:15:24.680 actually trigger a physical disgust response, which is unfortunate, but 0:15:24.720 --> 0:15:25.800 that is what happens. 0:15:26.160 --> 0:15:28.520 Yeah, it seems like something everyone should be able to 0:15:28.520 --> 0:15:31.640 empathize with because wind to scratch an itch is universal. 0:15:31.720 --> 0:15:37.240 But obviously there's acceptable scratching and unacceptable scratching, right right, And. 0:15:37.160 --> 0:15:39.800 Then there's this itches that don't respond like even to 0:15:39.920 --> 0:15:43.160 excessive scratching, meaning you could scratch and scratch and never 0:15:43.320 --> 0:15:44.840 actually get at these itches. 0:15:44.920 --> 0:15:46.200 Yeah, which sounds like torture. 0:15:46.920 --> 0:15:49.440 No, I really does. And there's actually something called a 0:15:49.520 --> 0:15:53.600 neuropathic or neurological itch which is a type of itch 0:15:53.800 --> 0:15:56.840 under the skin that you actually can't scratch to relieve 0:15:56.880 --> 0:15:59.920 because it's caused by nerve damage rather than issues related 0:15:59.920 --> 0:16:02.240 to the skin, and it can be caused by things 0:16:02.280 --> 0:16:07.200 like diabetes or shingles, brain lesions, or liver diseases. There's 0:16:07.280 --> 0:16:09.480 you know a host of other things that can lead 0:16:09.520 --> 0:16:11.560 to this, and you know, the itch tends to be 0:16:11.680 --> 0:16:14.920 chronic and difficult to treat, and there's really not much 0:16:15.000 --> 0:16:15.880 you can do about it. 0:16:16.240 --> 0:16:17.920 Yeah. I remember there was like a New Yorker piece 0:16:17.920 --> 0:16:20.120 about a woman who had an itch on her skull, 0:16:20.160 --> 0:16:22.240 and she just couldn't stop scratching at it, and it 0:16:22.440 --> 0:16:24.680 just like led to all sorts of issues, which just 0:16:24.720 --> 0:16:27.080 sounds miserable, but you know, there are also things that 0:16:27.120 --> 0:16:29.640 are kind of the opposite of that. In the nineteen fifties, 0:16:29.960 --> 0:16:33.240 there was this scientist named J. R. Traver who suffered 0:16:33.240 --> 0:16:37.160 from a condition called delusional parasitosis. It's this condition where 0:16:37.240 --> 0:16:40.440 people have become convinced that they're infested with parasites, which 0:16:40.560 --> 0:16:43.880 leads to itching. And trav refused to accept that this 0:16:44.080 --> 0:16:46.680 was just a delusion, so she published a paper about 0:16:46.680 --> 0:16:50.320 her experience combating what she called skin mites. She visited 0:16:50.360 --> 0:16:53.600 tons of doctors, used dangerous pesticides on herself, tried to 0:16:53.600 --> 0:16:56.760 scratch the phantom mites out with fingernails, and it went 0:16:56.800 --> 0:16:59.840 on for her whole life. Traver's actually started to itch 0:17:00.120 --> 0:17:03.960 und her fortieth birthday and continued scratching at these delusional 0:17:04.000 --> 0:17:08.280 itches until she died forty years later. Now, unfortunately, since then, 0:17:08.359 --> 0:17:12.000 other people with delusional parasitotosis have pointed to travers work 0:17:12.119 --> 0:17:15.159 as evidence that in fact they do have an itchy 0:17:15.320 --> 0:17:19.840 parasitic infection and not a psychiatric condition, which it actually 0:17:19.880 --> 0:17:20.520 is well. 0:17:20.680 --> 0:17:22.400 I mean that also just sounds like torture. 0:17:22.760 --> 0:17:24.920 Yeah. I imagine thinking your body was covered in mites 0:17:24.920 --> 0:17:27.720 for forty years, it would be like constant scabies, right. 0:17:28.160 --> 0:17:30.760 Yeah, I actually speaking of that you were talking about 0:17:30.800 --> 0:17:33.680 you looked into scabies, right, Like, can you actually explain 0:17:33.720 --> 0:17:35.040 it a little for uce. I feel like it's one 0:17:35.040 --> 0:17:38.399 of those words that's used without people actually understanding it. 0:17:38.920 --> 0:17:42.160 Yeah, and weirdly, I've heard of people getting it recently. 0:17:42.240 --> 0:17:44.840 But scabies is a skin condition that causes almost this 0:17:45.000 --> 0:17:49.520 like unbearable itchness, and it's caused by tiny mites that 0:17:49.600 --> 0:17:51.800 do burrow into your skin. Like. The mites have been 0:17:51.880 --> 0:17:56.320 around forever, but it wasn't until the eighteen thirties eighteen 0:17:56.359 --> 0:18:00.760 thirty four at the Hospital Saint Louis in Paris, that 0:18:00.840 --> 0:18:03.560 the mites were discovered as the cause of scabies, and 0:18:03.760 --> 0:18:06.160 at the time about sixty five percent of the beds 0:18:06.400 --> 0:18:09.639 in the hospital were occupied by patients suffering from scabies. 0:18:10.040 --> 0:18:13.439 It was a Corsican student named sf Ernucci who had 0:18:13.440 --> 0:18:16.080 been taught by peasant women of his home island how 0:18:16.080 --> 0:18:19.399 to extract the mites with a pin, and he showed 0:18:19.440 --> 0:18:21.639 the method to the doctors at the hospital. 0:18:22.480 --> 0:18:25.440 So people actually had to be hospitalized for scabies. 0:18:25.720 --> 0:18:28.400 Yeah, it can be really debilitating, and scabies was also 0:18:28.440 --> 0:18:31.880 a big problem during the American Revolution. This was before 0:18:31.920 --> 0:18:34.320 they discovered the cause with skin mites. They called it 0:18:34.480 --> 0:18:37.959 the itch. And in fact, it happens at Valley Forge 0:18:38.000 --> 0:18:41.560 when George Washington is there and he issues this general 0:18:41.680 --> 0:18:45.520 order that proclaims, quote being also informed, many men are 0:18:45.560 --> 0:18:48.879 rendered unfit for duty by the itch. The commander in 0:18:48.960 --> 0:18:52.560 chief orders and directs the regimental surgeons to look attentively 0:18:52.640 --> 0:18:54.800 into this matter, and as soon as the men who 0:18:54.840 --> 0:18:58.000 were affected with this disorder properly disposed in huts, to 0:18:58.040 --> 0:19:00.560 have them anoided for it. I mean, it's crazy. 0:19:01.040 --> 0:19:03.600 It's amazing that the itch was enough of a concern 0:19:03.640 --> 0:19:06.280 in the middle of a very bloody war, Like it 0:19:06.359 --> 0:19:09.399 just speaks to how bad these afflictions are. And so 0:19:09.440 --> 0:19:11.719 I think one of the central questions of life, mango 0:19:11.840 --> 0:19:15.040 and here it is to scratch or not to scratch? 0:19:15.640 --> 0:19:17.840 Yeah, one of Hamlet's lesser known soilquy. 0:19:18.160 --> 0:19:20.840 Yeah, it was a really powerful one. So we all 0:19:20.880 --> 0:19:22.840 have this reflex to scratch an itch. But it's a 0:19:22.880 --> 0:19:26.080 big question, like to scratching help or hurt us, and 0:19:26.119 --> 0:19:29.600 it's a question. Scientists are actually looking into this study 0:19:29.640 --> 0:19:32.000 as recently as twenty twenty three. It was at Harvard 0:19:32.040 --> 0:19:34.720 Medical School and it showed for the first time that 0:19:34.760 --> 0:19:40.200 a common skin bacterium Staphylococcus eras or S RAS, can 0:19:40.280 --> 0:19:44.000 cause an itch by acting directly on nerve cells. So 0:19:44.040 --> 0:19:47.280 this helps explain why common skin conditions like exima and 0:19:47.359 --> 0:19:52.399 atopic dermatitis are often accompanied by persistent itch. So in 0:19:52.440 --> 0:19:55.919 these conditions, the equilibrium of micro organisms that keep our 0:19:55.960 --> 0:20:00.960 skin healthy is often thrown off balance allows this you know, 0:20:01.080 --> 0:20:04.880 bacteria to flourish, and so it can cause an itch 0:20:04.920 --> 0:20:08.639 by instigating a molecular chain reaction that culminates in the 0:20:08.880 --> 0:20:09.960 urge to scratch. 0:20:10.760 --> 0:20:14.040 But why would a microbe like cause us to itch? 0:20:14.359 --> 0:20:18.160 Evolutionary speaking, like, what's in it for the bacterium, It's 0:20:18.160 --> 0:20:18.840 a good question. 0:20:18.880 --> 0:20:22.080 I mean, researchers say that the pathogens may be hijacking 0:20:22.119 --> 0:20:26.639 the itch, sensation and other neural reflexes to their advantage. So, 0:20:26.720 --> 0:20:30.320 for example, previous research has shown that the TB bacterium 0:20:30.440 --> 0:20:35.359 directly activates vagual neurons to cause cough, which might enable 0:20:35.359 --> 0:20:38.040 it to spread more easily from one host to another. 0:20:38.520 --> 0:20:41.800 There's another researcher that speculates that quote the itch scratch 0:20:41.920 --> 0:20:45.040 cycle could benefit the microbes and enable their spread to 0:20:45.160 --> 0:20:49.440 distant body sites and to uninfected host That's interesting. 0:20:49.520 --> 0:20:51.359 I feel like you always hear people say don't scratch, 0:20:51.400 --> 0:20:54.240 it'll make it worse, But what it actually means is like, 0:20:54.280 --> 0:20:57.560