Insight into 'contagious itch'

<span style="font-size: 12px;">http://www.wiley.com/</span>Mar 23 2011

Can you catch an itch? The answer is yes.

Dermatologist Gil Yosipovitch, M.D., of Wake Forest Baptist Medical Center, has been researching what's known as "contagious itch."

Contagious itch is visually transmitted, said Yosipovitch, and anecdotal evidence suggests it occurs in daily life when we see other people itch and scratch. A team of researchers led by Yosipovitch set out to systematically investigate contagious itch because the exact mechanism underlying this type of "itch transmission" is not well understood, and insights into what's happening in the brain during this transmission are lacking.

"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," Yosipovitch said. "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."

The new findings appear online in The British Journal of Dermatology. The study was supported by a grant from the National Eczema Association.

Yosipovitch and co-researcher Alexandru Papoiu, M.D., Ph.D., also of Wake Forest Baptist, examined the effect of visual cues of itch on the perception of a local itch inducted experimentally and in the induction of scratching, in a controlled setting. The scientists compared 14 healthy subjects, who received histamine or a saline control applied to their forearm, with 11 patients who had atopic dermatitis (AD). All study participants were monitored as they watched short video clips of people scratching or in a relaxed state, and their behavior analyzed.

Researchers found those with AD had a higher itch intensity and scratched more frequently while watching the videos of other subjects scratching. Of interest, said Yosipovitch, is that the visually-induced itch had a scattered, wide body distribution of scratching.

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

Yosipovitch and Papoiu point out that this is an early observational study and additional studies conducted. They hope the next step will be to conduct MRI scans to investigate study participants' brain mechanisms while inducing itch. By understanding the itch and scratch response, they hope eventually to be able to develop techniques like relaxation and meditation or medications that could target specific brain areas to reduce the severity of itch expression.