Science homing in on mystery of itch, joy of scratch

Science has barely begun to scratch the surface of why an itch itches, and how to make it stop.

The itch-scratch cycle sits right at the fascinating intersection of pleasure and pain, reflex and compulsion, but it has received relatively little scientific attention. Ten years ago, one of the small band of international itch researchers called itching "sadly neglected," an "orphan symptom."

New developments are slowly beginning to refine scientific understanding of itches. They include the identification of nerve fibers devoted to transmitting itchy sensations, of brain sectors that process itch, and of molecules that seem to provoke itch. Itch experts hope that better treatments for itchy patients will soon follow.

People who sail through the occasional mosquito bite without a conscious thought may be unmoved by this news. But for the many others whose itch-scratch cycle has been deranged by yet-unknown neurochemicals into a tortured process that scars their skin, destroys their sleep and sometimes sends them to the brink of suicide, the dearth of scientific understanding and treatment options for itches is deeply frustrating.

"So many people suffer from itch," said Dr. Gil Yosipovitch, an associate professor of dermatology at Wake Forest University Baptist Medical Center in Winston-Salem, N.C., who has coordinated several international itch conferences. But financing for itch research is hard to come by, and effective treatment options for itchy patients are quite limited. "I do believe that our patients deserve better," Yosipovitch said.

Anyone doubting his word might pay a visit to Yosipovitch's Web site, www.itchforum.com, and watch five short video clips of patients with the itchy skin condition called atopic eczema. Filmed at night during sleep, the patients writhe in bed, unconsciously clawing at their faces, torsos, ankles and feet.

Itching is a sensation that links the skin, the spinal cord and the brain in a kind of circular neural superhighway with exits all along the way. An itch may start anywhere along the loop — or even in organs like the liver far removed from the loop — and the process may then escalate into a vicious high-speed circular chase of itch and scratch, one worsening the other.

Sometimes, finding and treating a problem far afield from the skin itself is the only thing that can stop the cycle.

The simple mosquito bite is one of the few causes of itching that scientists feel they understand fairly well, and even it is full of unknowns.