March 24, 2011 -- Itching, like yawning, may be contagious, causing people to feel an urge to scratch after they see another person scratching. That’s according to a new study published in the British Journal of Dermatology.
Scientists at Wake Forest Baptist Medical Center were researching what they call “contagious itch” that is visually transmitted.
“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,” one of the study researchers, dermatologist Gil Yosipovitch, MD, of Wake Forest Baptist Medical Center, says in a news release.
Design of Itching Study
The study participants received either histamine, a substance that can cause itching, or saline, a substance that does not cause itching, applied to their forearms. Histamine, when applied to a study participant with atopic dermatitis, was put on an area of skin that did not have a rash. All participants were monitored while they watched short video clips of people either scratching, or in a relaxed state, so that their behavior could be analyzed.
Those with atopic dermatitis had a higher itch intensity and scratched more often while watching the videos of other people scratching.
People with the skin condition “reported the intensity of itch sensation significantly increasing” as they watched the videos of people scratching, the researchers write. This was true for nine of the people with the skin disorder, but the other two apparently weren’t as bothered.
“The analysis of scratching behavior of [atopic dermatitis] patients and healthy subjects revealed that atopics watching the itch video doubled the overall duration of scratching episodes,” the researchers write. These people also scratched in more places and for a longer duration than healthy participants watching the itch videos.
Brain Scans to Study Itching on Horizon
The results of the experiments show “that the power of the brain is pretty extreme,” Alexandru Papoiu, MD, PhD, also of Wake Forest Baptist, says in the news release. “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.”
By understanding what’s going on in the brain, “we may be able to develop future therapies that can target these areas and relieve the itch impulse,” Yosipovitch says.
The scientists stress that the study is early and observational in nature, and plan next to conduct magnetic resonance imaging (MRI) scans to study brain mechanisms while inducing itching.