The Mystery and Power of the Itch

As you read this, try not to itch — or scratch. Dr. Atul Gawande, a surgeon and staff writer at The New Yorker, found himself itching a lot while writing his latest article, simply called "The Itch."

What exactly is an itch?

"It is hard to define," Gawande tells Robert Siegel. "No one's improved on the definition from 1660: 'An unpleasant sensation that provokes the desire to scratch.' "

You asked.

"For the longest time," Gawande says, "scientists had theorized that itching was just a grade of pain — a very mild form of pain — and that it must be transmitted along pain receptors."

In the late 1980s, researchers did experiments where they gave subjects "very itchy things and could turn up the amount of itch substance driven into their skin," he says. "They found that they could reach a maximum tolerable level of itch and yet not have pain. That led them to separate the idea that there is itching and it's totally different from pain."

That Had to Hurt

In the article, Gawande describes some itching horror stories. Like the woman who was "so tormented by an itch that would not go away that she would scratch during her sleep," he says. One night, she scratched through her skull and into her brain.

Itching is often remedied by ointment or some other medication, but sometimes it's all in your head.

"There is itching that you can trace to something in the skin — a psoriasis, or a cream you shouldn't have been using," Gawande says. "But then there are itches that seem to come from something else altogether. You can have itches that come from jaundice, itches that come from a tumor even in your own brain.

"And there are people who are so tormented by constant itching ... who can scratch incessantly and feel that they're itchy for years on end to the point that they can't work, they can't function, they can't concentrate."

Itchy Thinking

Even the topic of itching has a powerful suggestive power over people, Gawande says.

"If I just describe to people the feeling of an ant crawling along the back of their neck and up their scalp, you can't help it, you start to feel itchy and you wonder if that thing is there."

That suggests that there's "something more interesting to our perceptions than just that you trigger a nerve, it goes up your spinal cord to your brain and then it rings a bell in the brain, like a clapper ringing a bell," Gawande says. "Here are cases where you don't have the clapper and yet the bell continues to ring."

Gawande found himself itching even as he wrote the article — especially when he was describing how lice cause an itchy scalp or how a group of flies could make you itchy just by brushing lightly across your skin.

Now, stop scratching.

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