Researcher explores itching as a disease

PHILADELPHIA – Dermatologist Gil Yosipovitch believes itch should be studied and treated as a disease in itself, not just a symptom.

That’s why he founded the International Society for the Study of Itch in 2005. And that’s partly why he left North Carolina’s Wake Forest University six months ago to create the Itch Center at Temple University School of Medicine.

“We’re behind our colleagues in the field of pain,” said Yosipovitch, who is also the new chair of Temple’s dermatology department. “I believe in five years, there will be U.S. centers dedicated to itch, just like many universities now have pain clinics.”

The need is clear. Itch is more than just an occasional annoyance from dry skin or a bug bite. A recent German study suggests that for 17 percent of adults, itch is an intractable, life-disrupting sensation caused by skin disorders, kidney and liver disease, diabetes, lymphoma, HIV, and nerve damage.

These chronic types of “pruritis,” as doctors call itch, are not only barely understood, but existing treatments often are barely effective, Yosipovitch wrote recently in the New England Journal of Medicine.

Yosipovitch envisions the Itch Center as a broad collaboration with researchers in basic, medical, and behavioral sciences.

“I also want to establish an itch ‘school’ to teach patients coping mechanisms, such as relaxation and distraction techniques,” he said. “I’m a believer in the holistic treatment of itch. I don’t care if it’s hypnosis, acupuncture, yoga – if it works for some patients, it’s worth trying.”

In a new book, “Living With Itch: A Patient’s Guide,” Yosipovitch and his coauthor explain that the skin, nervous system, and brain are all involved in itch transmission, with various chemical messengers helping at each level.

Because pain follows the same route, scientists have long debated the connection between itch and pain. Originally, itch and pain were believed to have completely separate sets of neurons. Then itch and pain were believed to share neural pathways, with itch being a weaker form of pain.

In 1997, German researchers found nerve fibers that transmit only itch. More recently, nerves have been identified that can transmit itch or pain.

While the interaction remains mysterious, it is clear that painful stimulation can relieve itch. That’s the basis of many common itch therapies – including very hot or cold showers, and capsaicin, the compound that makes peppers hot.

Conversely, inhibiting pain may trigger itch. “When people take pain medications, such as morphine, pain is relieved but people can start to itch,” the “Patient’s Guide” notes.

In his own research, Yosipovitch has sought to identify chemical messengers involved in hard-to-treat itch, in hopes of finding a target for new therapies.

“We’re also studying sweat, which aggravates itch, to analyze what molecules contribute to the itch,” he said.