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Scratching an Itch Feels Good, But Why and Where

2012-02-01 10:14
Itching skin

Scientists have already discovered why scratching an itch feels good, but does that pleasurable feeling apply to an itch anywhere on the body? A world-renowned itch expert has explored the effectiveness of scratching on three different sites on the body and also reported why this information is important.

Where does scratching an itch feel the best?

An itch is a common human occurrence, and scratching an itch generally feels good. However, what’s happening below the surface of the skin has puzzled researchers.

A study published in Nature Neuroscience in 2009 offered some clues when University of Minnesota neuroscientists suggested that the mechanism by which scratching an itch offers relief occurs not on the skin but deep within the central nervous system. More specifically, they noted (using a monkey model) that scratching involves the spinothalamic tract (STT) neurons in the spinal cord.

The scientists also pointed out that itching and scratching in humans likely has other components, including emotional and psychological factors.

In the current study, undertaken by itch expert Gil Yosipovitch, MD, PhD, professor of dermatology at Wake Forest Baptist Medical Center, and his team, the goal was to evaluate itch relief at different sites on the body. The investigators analyzed itch intensity and the amount of pleasure associated with scratching each itch location at 30-second intervals over a 5-minute period.

Eighteen volunteers participated in the study, during which the investigators applied cowhage spicules on a small area of skin on their ankles, forearms, and backs. Cowhage spicules is a tropical plant that causes intense itching when it makes contact with the skin.

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Itching and scratch relief were less intense on the forearm. Yosipovitch also noted that “the pleasurability of scratching the ankle appears to be longer lived compared to the other two sites.”

Why is this information important? If you suffer with an itchy skin condition such as psoriasis or eczema, these findings may be meaningful for you someday. Yosipovitch explained that the ankle and back are commonly involved in such skin disorders, and that understanding why these sites are more affected may help lead to development of treatments for patients who have these itchy problems.

So while scratching an itch feels good, research that helps explain why could eventually make many people feel much better.

SOURCES:
Bin Saif GA, Papoiu ADP, Banari L, McGlone F, Kwatra SG, Chan Y-H, Yosipovitch G. The pleasurability of scratching an itch: a psychophysical and topographical assessment. British Journal of Dermatology 2012; DOI: 10.1111/j.1365-2133.2012.10826.x

Davidson S, Zhang X, Khasabov SG, Simone DA, Giesler GJ. Relief of itch by scratching: state-dependent inhibition of primate spinothalamic tract neurons. Nature Neuroscience 2009 May; 12(5): 544-46

Image: Courtesy of Wikimedia Commons

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Comments

OHHHH - yes, a good back scratching is the best. I may need to see my dermatologist. hmmm. Thanks for this ...so interesting.
Yes, I always find studies that explore the little things we take for granted or that we don't bother to think about to be especially interesting. Next time I scratch an itch, I'll be thinking about why it feels so good!