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Scratching An Ankle Is Hard To Beat

Now that feels good.
Arman Zhenikeyev
/
iStockphoto.com
Now that feels good.

There are few more sybaritic pleasures than scratching an itch.

But according to a study just out in the British Journal of Dermatology, the intensity of the scratching delight varies with the location of the itch.

The research team was lead by Gil Yosipovitch, a man described as the "Godfather of itch." He and his colleagues at Wake Forest School of Medicine recruited 18 brave souls to take part in their study.

To induce itch, the researchers rubbed their subjects' skin with approximately 40 cowhage spicules. Just in case you're not familiar with cowhage spicules, they are tiny threads taken from a tropical legume.

OK, that's not really very helpful. Just take it on faith that when applied to a human's skin, cowhage spicules reliably induce intense itching.

Subjects didn't get to scratch their own itch. That would induce too much variability into the experimental design. Instead, the researchers rubbed their subjects' spicule-induced itches with a Medi-Pak 7-inch cytology brush (item #24–2199, General Medical Corp., Elkridge, Md.).

Probably not as satisfying as scratching with a nice sharp fingernail, but more reproducible.

The researchers tested the itch-scratch response at three sites: back, forearm and ankle. Turns out scratching the ankle produced a more pleasurable itch relief than the other two locations.

Now before you shake your head in wonderment that the researchers chose the back, ankle and forearm to make their measurements, be reassured that this is just the start. "Future studies," they write, "could also examine the scratching pleasurability associated with other itchy areas such as the scalp or the anogenital region." OK.

Whatever else they learn, the Wake Forest researchers have proven one thing: every itch has its niche.

Copyright 2021 NPR. To see more, visit https://www.npr.org.

Joe Palca
Joe Palca is a science correspondent for NPR. Since joining NPR in 1992, Palca has covered a range of science topics — everything from biomedical research to astronomy. He is currently focused on the eponymous series, "Joe's Big Idea." Stories in the series explore the minds and motivations of scientists and inventors. Palca is also the founder of NPR Scicommers – A science communication collective.