0:00

Support for unexplainable comes from progressive.

0:03

You're probably not just listening right now. Maybe

0:05

you're driving Maybe you're walking the dog.

0:07

But what if instead of that you

0:10

could be saving money by switching to

0:12

progressive? drivers who switch to

0:14

progressive can save nearly $750

0:16

on average and auto customers

0:19

qualify for an average of seven

0:21

discounts You can multitask right now

0:23

quote today and progressive comm Progressive

0:27

casualty insurance company and affiliates national average 12

0:29

month savings of $744

0:31

by new customers surveyed who saved with progressive between

0:33

June 2022 and May 2023 potential savings will vary

0:35

discounts not available in all states And situations support

0:38

for unexplainable comes from Another

0:40

podcast it's called technically optimistic

0:43

and it's about the world's

0:45

most valuable resource Data

0:48

our behavior is being tracked all the time and

0:50

then sold So

0:52

what does that mean for us in

0:55

season two of technically optimistic? host

0:58

Rafi Crickorian is gonna take you on a

1:00

deep dive into how our data is being

1:02

used and what we might be

1:04

able to do about it The show covers everything

1:07

from social media feeds to the most basic human

1:09

rights from the familiar to the

1:12

Intriguingly unexpected new

1:14

episodes of technically optimistic drop every Wednesday.

1:16

Listen now wherever you get your podcasts

1:21

You Everyone

1:26

itches you get a sunburn a

1:28

bug bite even a little stray

1:30

hair on your shoulder It's enough to make you

1:32

itch You'll probably feel it's your

1:34

than usual just by listening to this episode

1:36

because it's also contagious Itch

1:39

is usually something that we can just scratch away

1:42

But for lots of people it's more than an

1:44

annoying feeling if you have eczema Your

1:47

skin is already in flame. You have

1:49

intense itching more itching causes

1:51

more scratching more inflammation

1:54

more damage More itching

1:56

that's Brian Kim a dermatologist and yes

1:59

Brian I do I

2:01

have eczema, which has meant

2:03

some sleepless nights and wounds on my

2:06

body that I scratch open and won't

2:08

let heal, because the itch doesn't

2:10

go away. I've tried going

2:12

to doctors who've prescribed me creams and ointments,

2:14

tried changing my diet, tried bathing in

2:16

diluted bleach, which sounds crazy but it's

2:18

a thing, and some of

2:20

these things help but not for long. All

2:23

need signs to tell me that there's no cure-all fridge.

2:26

I already know, and it's not because I

2:28

haven't tried to figure it out. What

2:31

I didn't know was how little scientists understood

2:33

about itch at all. Ten

2:38

years ago, no one cared about it. It's

2:40

just amazing. It's really come a long ways.

2:42

When we first started setting edge, I thought

2:44

that all it was telling us was how

2:46

do we sense something outside of our body.

2:49

But what it's telling us is that it's teaching

2:51

us how we sense everything, not

2:53

just outside of our body, not just the

2:56

five senses, but a thousand senses. I'm

2:58

Manning-Want, and this is Unexplainable.

3:18

Brian's a dermatologist, but he was trained

3:20

as an immunologist. His specialty was

3:22

the immune system. So when he

3:24

started studying itch, people said a lot of

3:27

different things. A lot of people

3:29

said, well, itch is not a disease. It's

3:31

not important. It's not solvable. Oh,

3:33

you should just study pain. It's more important.

3:37

Even the cynical, like you can't make any

3:39

money in itch. Right? Like you're not

3:41

going to get funded. People have been saying

3:43

stuff like this forever because for

3:45

a long time, scientists fundamentally

3:47

misunderstood itch. It's actually

3:49

considered, or was considered a

3:52

mild form of pain. And

3:55

the idea there was that if we just studied pain

3:57

better, we could actually solve

3:59

the problem with it. But it

4:01

hasn't worked out that way. We've had

4:03

pain centers in clinical hospitals

4:05

and clinics all over the country,

4:07

but you never heard of really

4:09

about itch centers or itch specialties

4:12

in medicine, despite being such a

4:14

common experience of symptom. You

4:16

can kind of understand how itch and pain

4:18

were lumped together for so long because they're

4:20

both pretty unpleasant feelings. And they

4:23

come from the same place, our sensory nervous

4:25

system, specifically the part that

4:27

lets us feel touch, things like temperature and

4:29

pressure, pain. You have

4:31

your skin, which is kind of the barrier

4:33

to the outside world, and

4:36

into the skin are nerve fibers that go

4:38

in and they act like little electrical cables

4:40

that go back to your spinal cord. And

4:43

then there's a series of circuits that work its way up

4:45

into the brain. Anytime we touch

4:47

something, it triggers a specific receptor

4:49

at the end of these nerves and sends an

4:52

electrical signal down them. So

4:54

cold triggers the cold receptor, hot triggers the

4:56

hot one, and pain triggers the one

4:58

for pain. And for a

5:00

long time, scientists thought that there was no

5:02

dedicated itch receptor, no dedicated nerve. We

5:05

just thought that things that made us itch-y also triggered their

5:08

pain receptors. But in 2007, that changed

5:10

entirely. A

5:12

guy named Jifeng Chen, who

5:15

became my colleague later, had discovered the

5:17

first bona fide itch receptor

5:19

in the spinal cord. In other

5:21

words, the itch highway. What

5:24

that really meant to us was that actually

5:26

now this is not pain. This

5:29

is its own defined entity that's separate

5:32

from pain. And

5:34

that totally changed the way everyone

5:36

thought about itch, including myself. Once

5:40

itch was recognized as a unique feeling with

5:42

its own dedicated receptor and pathways in the

5:44

body, it became something scientists could

5:46

work with. A major effort

5:49

on our part was to develop drugs

5:51

that actually target itching very directly. The

5:54

idea was that these drugs could directly block off

5:56

itch receptors and stop the itch signal

5:58

from reaching the brain. Treating itch

6:00

turned out to be more complicated than it seemed, because

6:03

there isn't just one kind of itch receptor. Scientists

6:06

have found a bunch of them. Additional

6:08

pathways beyond the first itch receptor

6:10

have been identified. Across

6:12

different families, they actually have different flavors. These

6:15

different families of receptors are triggered by different

6:17

things. The most well-known are

6:19

probably those itch receptors triggered by histamine

6:21

molecules, which are molecules released by

6:24

your immune system, and they're partly why

6:26

inflammation and allergies can make you itchy. But

6:28

that's just one flavor of itch. If

6:32

you actually look at the science, there are

6:35

so many different molecules that cause itch. Itch

6:38

is probably many, many different sensations.

6:40

It could be anywhere from dozens

6:42

to maybe hundred sensations, we think.

6:45

For example, some bacteria can cause itch,

6:48

like one called Staph aureus. People

6:50

with eczema have way more of this bacteria on their

6:52

skin than other people do. Isaac

6:54

Chu's group at Harvard discovered that bacteria

6:57

trigger these itch nerves. I thought, wow,

6:59

that's interesting. Why are they directly sensing

7:01

bacteria? Things like pollen,

7:03

dust mites, animal fur, these can

7:05

also trigger itch nerves instead of just

7:07

creating inflammation. Nico Gaudenzio at

7:10

N CIRM and Kerry Selkle at

7:12

MGH detected that allergens

7:14

trigger itching directly. I was

7:16

like, wow, I'm in the allergy field. I'm a dermatologist.

7:19

I thought the immune system detected allergens,

7:21

not the nerve. I thought

7:23

the whole thing was you had a hypersensitivity

7:25

to peanut, not that your nerve detects peanut

7:27

first. Whoa. I

7:29

was like, this is a total flip of the script

7:32

on food allergy. This is flipping the script on how

7:34

I think about asthma. Everything I

7:36

just told as an immunologist is now thrown in,

7:38

not thrown into question, but at

7:40

minimum saying we need to revisit this.

7:44

We didn't know this guy was at the party all along. A

7:48

lot of these advances are only from the last few

7:50

years. There are so many more

7:52

pathways itch could take than scientists originally thought. It's

7:55

science was having its renaissance and something clicked

7:58

for Brian. I

8:00

realized, oh my gosh, it's

8:02

way more important than even itch. In

8:05

2019, Brian came across a paper that mapped out

8:07

a bunch of sensory nerves in the body. These

8:10

are nerves that connect our brains to our inner

8:12

organs, like the lung, the stomach, the gut. And

8:16

they looked a lot like the itch nerves that he had been

8:18

studying. Those

8:20

nerves that go to the skin, what we call the

8:23

cell bodies or the brain of those

8:25

nerves reside really close to your spinal cord,

8:27

okay? They're housed in this what we call

8:29

ganglia, they're kind of the head corners.

8:32

But housed within those same compartments

8:35

are other nerves that go to every

8:37

organ inside your body, not to your

8:39

skin, but inside your body. And

8:42

a lot of those nerves actually have

8:44

machinery that are shared

8:46

with these itch nerves. The itch

8:48

nerves and molecules that Brian had become so familiar

8:50

with on the skin were in

8:53

all these other organs. But why

8:55

are there these nerves that go to your

8:57

lung, your liver, your lymph

8:59

node, your spleen, your

9:02

colon that actually

9:05

look like itch nerves? Itch

9:08

might be more than skin deep. That's

9:12

it. Support

9:16

for the show comes from NetSuite. Are

9:20

you a business owner? Are

9:22

you trying to grow your business and save money? Let

9:26

me tell you about this system. It's

9:28

a cloud financial system. It

9:31

can do all kinds of things. And

9:36

it lives in the cloud. So

9:38

it can help your whole team, wherever they are. You

9:42

want to reduce IT costs? You

9:46

want to improve efficiency? If

9:49

so, you can join over 37,000 companies

9:51

that have already made the move to

9:54

NetSuite. Backed

9:57

by popular demand, NetSuite has extended

9:59

its one-of-a-kind flexible financing program for

10:01

a few more weeks. You

10:05

can head to netsuite.com/unexplainable.

10:08

netsuite.com/unexplainable.

10:20

Support for unexplainable comes from progressive

10:22

insurance. What are you doing right now? Are

10:25

you just listening or are you cooking dinner? Eating

10:28

dinner? Thinking about dinner? Okay,

10:31

maybe I should eat. But

10:33

there's so many other things you could be

10:35

doing like getting an auto quote from progressive

10:37

insurance. Drivers who switched to progressive

10:40

can save nearly $750 on average and

10:44

auto customers get even more discounts for

10:46

having multiple vehicles on your policy, being

10:48

a homeowner, all kinds of things. So

10:51

just like your favorite podcast, progressive will be

10:53

with you at least every Wednesday, about 46

10:55

or 47 weeks of the year. And

10:58

in progressive case, probably even more. You

11:00

can multitask right now. Quote your

11:03

car insurance at progressive.com to join the

11:05

over 28 million drivers who trust the

11:07

progressive. Progressive casualty

11:09

insurance company and affiliates national average 12 months savings

11:11

of $744 by new

11:14

customer survey to save with progressive between June 2022

11:16

and May 2023 potential savings on dairy discounts not

11:18

available in all states and situations. Support

11:24

for unexplainable comes from Squarespace. How

11:28

do they work? I don't really

11:30

know. Maybe something we should

11:32

look into on the show, maybe. But

11:35

if you use Squarespace, you don't need to know

11:37

how they work. You just do a

11:39

little bit of clicking and dragging and uploading

11:42

and bam, you got a website. I've used

11:44

Squarespace to make websites for an old band

11:46

of mine, for an afterschool program I used

11:48

to run and the whole

11:50

thing was so easy. I got to pick from

11:52

a bunch of sleek looking templates. I got

11:54

to customize it with all the pages and features

11:56

I wanted. I had these pages where

11:58

people could listen to music. where they can watch

12:01

videos, where they can find merch. And

12:03

it made it really easy for people to get

12:05

in touch when they needed. It all looked great.

12:07

The whole thing was painless. And

12:10

I still don't know how websites work. So

12:13

if you're in the market for a

12:15

brand new website, you can head to

12:17

squarespace.com/unexplainable to save 10% off

12:19

your first purchase of a website or

12:21

domain using code unexplainable.

12:37

In the last few decades, scientists have learned that

12:39

the infrastructure of itch is way more expensive than

12:42

we thought. And Brian Kim thinks

12:44

that itch could tell us about way more than just

12:46

our skin. Itch is the

12:48

tip of the iceberg in explaining to us how

12:51

we sense inflammation, how we now react

12:53

to inflammation. And then it's also telling

12:55

us how do we sense allergens, how

12:57

do we sense bacteria, how much of

12:59

my brain unconsciously unbeknownst

13:01

to me is

13:03

constantly sensing things throughout

13:06

my body. Scientists have found

13:08

nerves and receptors threading our internal organs

13:10

that look a lot like the ones

13:12

on our skin. So then

13:14

you say, why are these nerves so similar to the

13:16

nerves that go to the skin? Yeah,

13:19

why are they so similar? Do we know what

13:21

they're doing? We know a little

13:23

bit. A lot of it is a question mark,

13:26

because this is where the frontier emerges. So there

13:28

are nerves that have a very distinct identity.

13:31

So nerves that have, for instance, touch

13:33

quality are very, very

13:35

distinct. Actually, even structurally are different. But

13:38

these nerves are kind of within the

13:40

family of just these really slow, sensory

13:42

nerves. And then you layer on the

13:44

fact that they sometimes have molecules or

13:46

receptors that we know causes

13:49

itch in the skin. So you say,

13:51

oh, well, if that causes itch in the skin, then what

13:53

does it do in the gut? And

13:56

We thought, well, those organs don't

13:58

itch. They must

14:00

be doing something. Unique.

14:03

That me mimic. It

14:05

in some way. And it's kind

14:07

of a wild thought. Yeah. What do

14:09

you mean by mimic? It's. On.

14:11

Do I think that your lives node it?

14:13

Just know. Do I think you scratch your

14:15

lives? Don't know. I don't really think that

14:18

either. Okay but now when you get to

14:20

the lung he started makes sense of it

14:22

is they won't You know there are these

14:25

reflexes and alone that mimic itchy and scratchy,

14:27

mechanical or effects us to expel. He's like

14:29

coffee. Or. In the upper airway. so

14:31

like sneezing. And then if you go

14:33

to the. Not. There.

14:36

Are things that mimic ha like? If you

14:38

get. Diarrhea, It's

14:40

an expulsion event. You have motility, just

14:42

like your scroggin' What is

14:44

majority exactly? But our movement. He

14:47

got was a kind of oscillate

14:49

and move to try to move

14:51

food her stool right down so

14:53

that's a sense him to a

14:55

form of the got scratching Oh

14:57

and what we learn from it

15:00

is that every sensation. Also.

15:02

Requires. A reflex

15:04

movement. right? Like reaction.

15:06

A reaction. Exactly every arson requires a

15:09

reaction or whatever. that term is right.

15:11

Slow. So that motif is not limited

15:13

to it's. So. You're.

15:16

Saying that we can think of it's kind of

15:18

like a template. Just select, understand

15:20

our other organs sales, and react to

15:22

things. Yeah, yeah, exactly. That's a simple

15:24

way to put it. Maybe the body

15:26

just said, hey, It's. Is

15:28

all over the skin isn't so

15:31

many molecules can cause edge. It's

15:33

important a population level. But.

15:36

Maybe we can now use this. In.

15:38

Other ways to get rid of your and

15:41

properly. Get. Rid of stool? Probably

15:43

get rid of. Slum from the

15:45

airway properly help you to sneeze

15:47

or you don't get infected with

15:49

the virus. But. There's

15:52

another layer of their. Those. Simply.

15:54

Mechanical. Reflexes. But what it has told

15:57

us is that it actually. Also.

15:59

Has another. reflex in there that

16:01

goes beyond the mechanical. What

16:04

do you mean? So let's use itch

16:06

as an analogy. You have

16:08

a fleeting itch and you scratch, you cause

16:10

inflammation in your skin, but

16:13

then the inflammation, if you're a healthy individual,

16:15

the inflammation goes away. How does it go

16:17

away? What is that reaction that helps you

16:19

resolve that? Well, you could

16:21

think about almost every physiology in the

16:23

body in these terms. How

16:25

does any event know how to shut

16:27

off in the body? Because

16:30

your body senses that event and knows to

16:32

shut it off. And

16:34

that is the frontier of the biology. So

16:37

in other words, if you get an infection,

16:40

your immune system fights it off. But what we're saying

16:42

is that also your nervous system has to sense that

16:44

infection to actually help your immune

16:47

system shut it off in the right way and say,

16:49

hey, we sensed it. Here's our reaction.

16:51

We're gonna help you react to it. Shut

16:53

it out, back to health. And

16:56

now we can understand how if

16:59

such sensations or

17:01

reactions to those sensations become perturbed,

17:04

how this could lead to disease. So,

17:07

I mean, I guess if we could better

17:09

understand what these itch like nerves are doing,

17:12

then what could this lead

17:14

to? I think it could get

17:17

further than even what we just discussed. So

17:21

itch basically is a template for,

17:23

in my mind, now

17:25

understanding lots of different kinds

17:27

of sensation that are much more even

17:29

lofty than itch in some ways. If

17:32

you say the tip of the itch iceberg is

17:35

now going to tell us how

17:38

we understand diseases that are irritating

17:40

and involved

17:42

in kind of irritating sensations that make you

17:44

wanna expel things from the body or just

17:46

irritate you a lot, like interstitial

17:49

cystitis of the bladder, irritable

17:51

bowel syndrome, chronic coughing, gastritis,

17:55

esophageal reflux disease, all these things are

17:57

irritings that have no treatments. People

18:00

don't even think about it as a sensation. That's

18:03

a big frontier. Have

18:05

we definitively proven that there is

18:07

this incredible symphony across all these

18:09

diseases? Absolutely not. Okay. If

18:12

we did, it would not be a frontier. It

18:14

would be a busy, busy intersection

18:16

of many people. I

18:18

anticipate fully though that that is what's going

18:21

to happen in the next 10 years. It's

18:27

science has come a long way and it

18:29

has more to go. What Brian's

18:31

excited about is the potential that it has to

18:33

help us understand all kinds of other

18:35

sensations and diseases. But

18:37

for me, learning about itch itself has made

18:39

this eczema stuff feel a little

18:41

easier. Like maybe the

18:44

creams and the diets and the baths I did

18:46

weren't fully working because they weren't targeting the right

18:48

pathways. Or maybe the itch was

18:50

caused by more than one thing. I

18:52

don't know yet. But the science

18:54

of itch is giving me hope that if not

18:56

today, there will eventually be a treatment that works

18:58

for me and that anybody

19:00

with itch might be able to find the relief that they

19:02

need. This

19:17

episode was reported and produced by me, Mandy

19:20

Nguyen. We had editing from Jorge

19:22

Jess with help from Brian Resnick, sound design

19:24

and mixing from Christian Ayala, music

19:26

from Nolan Hasenfeld, fact checking from Melissa

19:28

Hirsch, and Meredith Hodnott runs the show.

19:31

Bird Pickerton turned to the platypus and told

19:33

her about the octopuses. She told

19:36

them about the attack. She told them about everything.

19:39

They turned to her and said, We

19:41

love you. Special

19:47

thanks to Li Wen Dang, Giliyas Povich,

19:49

Taylor Sheehan, and Heidi Kong. If

19:51

you have any thoughts about the show, send us

19:53

an email. We're unexplainable at vox.com. And

19:56

we'd love to hear your thoughts, your criticisms, your

19:58

suggestions. And if you can, please leave a comment. leave us

20:00

a review or rating wherever you listen. It really

20:02

helps us find new listeners. This

20:05

podcast and all of Vox is free, in part because

20:07

of the gifts from our readers and listeners. You

20:10

can go to vox.com/give to give today. Unexplainable

20:13

is part of the Vox Media Podcast Network, and

20:15

we'll be back next Wednesday. Support

20:30

for Unexplainable comes from Listening. Listening

20:32

is an app that makes it

20:34

easy to convert written text to

20:36

engaging sounding audio that you can

20:38

listen to anywhere. The app uses

20:40

realistic sounding AI voices that correctly

20:42

pronounce complicated technical terms, but

20:45

also sound natural, like actual human

20:47

beings, not robots, which they are,

20:50

but they don't sound like that. The

20:52

Listening app might just transform how you

20:54

consume reading material. Now you can

20:57

give it a shot for yourself, risk-free. Normally, you

20:59

get a two-week free trial, but listeners of our show

21:01

get a whole month free. Go

21:03

to listening.com/unexplainable, or use

21:05

code unexplainable at checkout.

21:08

Listening, your life just got a lot easier.