What makes you scratch that itch

Seeing other people scratching can cause your brain to trigger your own itch, researchers suggest.

The team at Wake Forest Baptist Medical Center investigated the causes of what's known as "contagious itch".

"It is conceivable that the neuronal networks or mechanisms underlying contagious itching may be similar to the ones involved in contagious yawning, a phenomenon that is still intensely studied, but not exactly clear," dermatologist Dr. Gil Yosipovitch said in a medical centre news release.

"The brain has such a powerful contribution to itch, and by understanding it, we may be able to develop future therapies that can target these areas and relieve the itch impulse," he added.

Scratching and eczema

Yosipovitsh and colleague Dr Alexandru Papoiu monitored 14 healthy volunteers who had histamine or a placebo applied to their forearm, and 11 people with atopic dermatitis (a type of eczema) as they watched short video clips of people scratching or in a relaxed state.

The participants with eczema had a higher itch intensity and scratched more often while watching the videos of other people scratching, compared to the volunteers without eczema.

The researchers said it was especially interesting to find that the visually induced itch led to scattered, whole body distribution of scratching.

"This shows that the power of the brain is pretty extreme," Papoiu said. "This speaks to the core of our being, to being particularly vulnerable to suggestions of itch, which can easily trigger a response from our central nervous system."

The study, funded by the National Eczema Association, appears online in the British Journal of Dermatology.


(Copyright © 2010 HealthDay. All rights reserved.)

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