30 January 2012
Ankle gets top rating for scratching pleasure
by Will Parker
American itch boffins have been studying which parts of the body produce the most pleasure when scratched. Their analysis of itch relief at different body sites and related pleasurability has been published in the British Journal of Dermatology.
World-renowned itch expert Gil Yosipovitch, who conducted the study, said he wanted to evaluate whether itch intensity was perceived differently at three body sites, and then investigate the correlation between the pleasurability and the itch relief induced by scratching.
Yosipovitch, from Wake Forest Baptist Medical Center, began by inducing itching on the ankles, forearms and backs of the study participants. To create the itch, he used cowhage spicules, which come from a legume found in tropical areas that are known to cause intense itching.
The spicules were rubbed gently in a circular motion for 45 seconds within a small area of the skin and then removed with adhesive tape. Itch intensity and scratching pleasurability were then assessed every 30 seconds for a duration of five minutes.
The results show that itch was perceived most intensely at the ankle and back, while the perception of itch and scratching relief were less pronounced on the forearm. Another major finding of the paper, according to Yosipovitch, is that "the pleasurability of scratching the ankle appears to be longer lived compared to the other two sites."
Yosipovitch is quick to dispel suggestions that the research may not have any practical application. "We see commonly involved areas such as the ankle and back in itchy patients with skin disorders caused by eczema or psoriasis," he said. "We never understood why those areas were more affected, and now we better understand that itch in these areas is more intense and pleasurable to scratch."
Intriguingly, while it is known that small nerve fibers are involved in unpleasant sensations such as itching and pain, Yosipovitch believes that there are also specific nerve fibers involved in pleasure. "If we could translate this to a treatment that induces a pleasurable relief sensation without damaging the skin, we may be able to help itchy patients," he concluded.