Research suggests why scratching is so relieving

In the first study to use imaging technology to see what goes on in the brain when we scratch, researchers at Wake Forest University Baptist Medical Center have uncovered new clues about why scratching may be so relieving – and why it can be hard to stop. The work is reported online in the Journal of Investigative Dermatology and will appear in a future print issue.

“Our study shows for the first time how scratching may relieve itch,” said lead author Gil Yosipovitch, M.D., a dermatologist who specializes in itch. “It’s important to understand the mechanism of relief so we can develop more effective treatments. For some people, itch is a chronic condition that affects overall health.”

The study involved 13 healthy participants who underwent testing with functional magnetic resonance imaging (MRI) technology that highlights areas of the brain activated during an activity. Participants were scratched on the lower leg with a small brush. The scratching went on for 30 seconds and was then stopped for 30 seconds – for a total of about five minutes.

“To our surprise, we found that areas of the brain associated with unpleasant or aversive emotions and memories became significantly less active during the scratching,” said Yosipovitch. “We know scratching is pleasurable, but we haven’t known why. It’s possible that scratching may suppress the emotional components of itch and bring about its relief.”

The reduced brain activity occurred in the anterior cingulate cortex, an area associated with aversion to unpleasant sensory experiences, and the posterior cingulate cortex, which is associated with memory. When participants reported that the scratching felt most intense, activation in these areas was lowest.

Yosipovitch said patients occasionally report that intense scratching – to the point of drawing blood – is the only thing that relieves chronic itch.

“This is the first real scientific evidence showing that itch may be inhibited by scratching,” he said. “Of course, scratching is not recommended because it can damage the skin. But understanding how the process works could lead to new treatments. For example, drugs that deactivate this part of the brain might be effective.”

The imaging studies also showed that some areas of the brain were made more active by the scratching, including the secondary somatosensory cortex, a sensory area involved in pain, and the prefrontal cortex, which is associated with compulsive behavior.

“This could explain the compulsion to continue scratching,” said Yosipovitch.

One drawback to the study is that the scratching occurred in the absence of itch. Yosipovitch’s team is continuing the research by evaluating whether the findings will apply to chronic itch.

Understanding more about chronic itch is important, Yosipovitch said, noting that more than 30 million Americans suffer from eczema and that almost half (42 percent) of kidney dialysis patients are bothered by moderate to severe itch. In fact, those kidney dialysis patients with itch have a 17 percent higher mortality rate, likely from a loss of sleep, according to a report in Nephrology Dialysis Transplantation.

Source: Wake Forest University

Related stories:

Scratch no more: Gene for itch sensation discovered
Itching for a better anti-itch remedy? Your wish may soon be granted now that scientists at Washington University School of Medicine in St. Louis have identified the first gene for the itch sensation in the central nervous system. The discovery could rapidly lead to new treatments directly targeting itchiness and providing relief for chronic and severe itching.
Probing Question: What makes a song catchy?
A catchy tune isn't always a good thing. If it contains an infectious chorus, even a song you dislike might refuse to leave your head. ("Achy Breaky Heart," anyone?) The choice of descriptors is not lost on Keith Duffy, a professor of rhetoric and composition at Penn State Schuylkill and a musician on the side. "Oddly enough," Duffy said, "this same rhetoric also describes communicable diseases."
Mirror self-recognition in magpies
Self-recognition, it has been argued, is a hallmark of advanced cognitive abilities in animals. It was previously thought that only the usual suspects of higher cognition—some great apes, dolphins, and elephants—were able to recognize their own bodies in a mirror. In this week's issue of PLoS Biology, psychologist Helmut Prior and colleagues show evidence of self-recognition in magpies—a species with a brain structure very different from mammals.
Worms take the sniff test to reveal sex differences in brain
Buttery popcorn or fresh green vegetables? Your answer tells a lot about you. Now, scientists say that the way that thousands of tiny worms have answered that question likely reveals a lot about you and your brain, too.
Gene triggers obsessive compulsive disorder-like syndrome in mice
Using genetic engineering, researchers have created an obsessive-compulsive disorder (OCD) - like set of behaviors in mice and reversed them with antidepressants and genetic targeting of a key brain circuit. The study, by National Institutes of Health (NIH) -funded researchers, suggests new strategies for treating the disorder.
Racing neurons control whether we stop or go
In the children's game "red light green light," winners are able to stop, and take off running again, more quickly than their comrades. New research reveals that a similar race goes on in our brains, with impulse control being the big winner.
Scientists unravel the secret world of elephant communication
It's a cloudless July afternoon in Etosha National Park in northern Namibia, and ecologist Caitlin O'Connell-Rodwell is scanning the horizon for elephants. "It's so fantastic here," she says. "We're constantly seeing elephants, rhinos, zebras, ostriches - it's the Garden of Eden."
A research associate in the Stanford University School of Medicine, O'Connell-Rodwell has come to one of Africa's premiere wildlife sanctuaries to explore the mysterious and complex world of elephant communication. She and her colleagues are part of a scientific revolution that began nearly two decades ago with the stunning revelation that elephants communicate over long distances using low-pitched sounds that are barely audible to humans.
Possible Shakespearean theater found in London
(AP) -- The theater where "The Merchant of Venice" and "Romeo and Juliet" likely debuted and where William Shakespeare himself may have trodden the boards has likely been discovered in east London, archaeologists at the Museum of London said Wednesday.

News discussion:

Medicine & Health news