• What is an itch, anyway? Another clue found

    By Tia Ghose, LiveScience 

    A mysterious source of itchiness has been found. Certain nerve cells are specialized to detect itchy sensations, and those receptors don't detect painful sensations, according to a new study.

    The finding, published Dec. 23 in the journal Nature Neuroscience, helps resolve a long-standing debate over whether itchiness is just a weird form of pain. Additionally, now that they have pinpointed the responsible nerve fibers, researchers could silence those nerves to develop better anti-itch treatments, said Ethan Lerner, a neuroscientist at Harvard University who was not involved in the study.

    "This is a very convincing piece of work," Lerner told LiveScience. Scientists "can perhaps target this particular type of nerve as a means of treating itch, but still allow you to experience the protective aspect of pain."

    For decades, why we itch has been a mystery. While some pain nerves have been found to fire in response to itchy stimulants, nerves that responded solely to itch proved elusive. Some researchers even wondered whether itch and pain were always processed by the same nerve fibers, but interpreted by the brain differently, said study co-author Xinzhong Dong, a neuroscientist at Johns Hopkins University.

    But the the urge to scratch seemed different in key ways from the experience of pain. For instance, when a mosquito bites, most people feel a powerful desire to scratch the bite, while the pain of touching a hot stove causes people to recoil, Dong told LiveScience.

    To identify cells that sense itch, Dong and his colleagues genetically engineered mice whose nerve cells glowed fluorescent green when firing. The researchers then exposed the mice to irritating compounds, such as histamine and the active ingredient in itching powder, and looked for nerves that fired (and glowed green) as a result.

    When the researchers burned out the nerves that lit up, the mice scratched a lot less, suggesting they were less itchy.

    But that wasn't enough to prove that the nerves only sense itch, because in theory those neurons could also sense pain. Therefore, the researchers specifically activated just those itch-detecting nerves in the faces of the mice. The animals then scratched their faces with their back paws, which they only do when itchy. (When they are in pain, they wipe their faces with their front legs.)

    The newly discovered itch nerves sit inside the spine, near the spinal cord, and only innervate locations within the skin. That explains why people feel the urge to scratch their skin, but don't feel itchy in internal organs, Dong said.

    "You can't have an itchy pancreas," he said.

    The new findings are important because they provide a target for anti-itch medications. Current options, like anti-histamines or steroids, usually work by reducing inflammation, while many only eliminate the cause of itch for a narrow subset of problems, such as hives, Lerner said.

    "Steroids are sort of a shotgun, and antihistamines, almost all the time, are hitting the wrong target," he said.

    While the newly discovered nerves can't explain all itchiness (there are probably other nerves which sense both itch and pain ), targeting these nerves could be a huge improvement over current treatments, Lerner said.

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    Another woman had simply compartmentalized the anti-sex parts of Christianity and decided to trust her instincts: “I have my body image issues — I don't like sitting in my swimsuit next to someone skinny, stuff like that — but with a guy, naked, I feel really comfortable. I’ve always just known what to do.”

    For most of these women, their physical convictions were just as important as their spiritual convictions; if the two came into alignment, all the better. One woman, mentally flirting with the idea of sex, experienced clarity one night in Vegas.

    "I met this hot cop,” she told me, “like an actual cop who was hot, not a Chippendale. We started making out in the casino — really going at it, it was amazing — and he persuaded me to come up to his room, where we fell onto his bed. He pulled up my dress and got naked all of a sudden and asked, ‘Can I put it in?’ I was totally horrified. I said absolutely not. Then he just sort of put it on top of me. I pretended I heard my phone ringing and basically ran away.”

    “It’s a rule to protect you.”

    I asked these women the same question over and over. Why is sex before marriage considered wrong? Essentially, everyone answered the same way: “I believe in the Bible, and the Bible says so.” Most added, “But I’m not going to judge anyone who does it.” Most, of course, were also doing it.

    “It has more to do with your identity as a Christian,” one woman said. “How you see yourself, how you want to feel, how you want to be treated. This is hard for me to articulate, but I think that any sin that we commit comes from an internal issue that we have with ourselves — something we’re born with, like pride or greed. With sex, it could maybe be a problem with self-control, or wanting to receive a certain type of attention or feel a certain way.”

    “I think it’s a rule to protect you,” another woman said. “To keep you from opening yourself up emotionally to the wrong people, to heartbreak and hurt.”

    I remember when I came home from school in fourth grade wearing my very first purity ring. I waved my hand in the air proudly. “Oh Lord,” said my mom, who is an evangelical Christian. “Take it off, take it off now.”

    “I was never acting out of an urge that was pure."

    Guilt, bargaining, and confusion all played at least minor roles in each woman's story. One talked about a high school boyfriend, saying, "I believed that God wanted the two of us to be together, but that we'd cursed our relationship forever because we'd had sex. There was an inner voice just screaming at me about what I’d done, much louder than the voices that told me not to lie and cheat and steal. I would read books and identify with characters who were prostitutes, that’s how low I felt."

    Another brought up middle-school masturbation: "I knew what I was doing, even though I didn’t know the word for it, and I knew it was sinful. I knew even then that I wasn’t taking care of my body in a holy way. I wasn’t acting out of an urge that was pure."

    My friend Maya, after her assault: “I was furious at God. I couldn’t understand how I was the only one of our friends who made the decision to stay a virgin, and I loved the decision and defended it, and then He let this happen.”

    Purity, this tightly conditioned idea, with so much more to give! In my own life, the times I've felt the purest have involved another trinity — sex, drugs, etc. — and the God that I came to know as a kid, that vague metaphysical presence, was always there in my bones to bless me.

    “I have a huge sex drive – it’s how God made me.”

    All the women I talked to readily admitted that the evangelical church doesn’t handle sexuality well. From the woman who’d waited until marriage: “It's a big institutional and doctrinal flaw, this idea that sex is bad, sex is wrong. When you're told that your whole life, how are you supposed to just flip that switch when you finally get around to doing it?"

    I asked her how long it took to hit her stride with her husband, to feel comfortable having sex. “A while!” she said. “Two or three months, because he was studying for the bar nonstop and we could only really try on weekends. We laughed about it, like, thank goodness we didn’t have anyone else to compare this to.” She added, “But now it’s wonderful. And you know, sex is all over the Bible. God commands us to have communion with each other.”

    They all told me that they hoped there would be a generational change in the church, a shifting of priorities. “It’s not our job to grade,” one woman said forcefully. “The emphasis we put on sin is out of proportion. That’s the biggest problem I have with the church.”

    Another said, “We should change the conversation. It should be understood that sex is beautiful. It should be more about what you might want to protect yourself against, and how. It should be more about not doing things that could harm you.”

    “If I’m truly a Christian, I should be able to understand what grace is. And feeling terrible is not grace,” said another woman, who’d described herself as having “a huge sex drive — it’s how God made me.”

    She added, “I went to a bachelorette party where they were asking all the married girls for sex advice for the bride-to-be. I just sat there, listening to them talk about fussy lingerie and complicated games and weird sex menus, and I didn’t say anything, even though I wanted to be like, ‘Girl, just buy a vibrator.’ You know, I have a lot of friends that are waiting, or have waited, and it was great for them. But that’s just not how it’s going to be for me.”

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  • Itchiness is contagious, just like yawning

    featurepics.com

    By Meghan Holohan

    For some people, hearing about a bug bite or a rash is enough to cause them to furiously dig at their own unaffected skin. Even some doctors who treat people with shingles report feeling itchy after witnessing their patients scratching. And we'd bet many of you readers are feeling itchy right this very second. 

    It seems humans commonly catch itches from one another, but scientists hadn’t proven it—until now. Researchers found that itching is contagious much like yawning and laughing.

    “With itching, there [was] only anecdotal evidence that watching [a person] itch induces itching,” explains Henning Holle, a lecturer in the psychology department at the University of Hull in England. “We wanted to know whether contagious itch would effect everyone.”

    Holle asked 51 adults to take a personality test that ranks the Big Five personality traits of openness, conscientiousness, extroversion, agreeableness and neuroticism. Then using functional magnetic resonance imaging, or fMRI (a technique that detects brain activity by monitoring blood flow in the brain), the subjects watched either a video where someone was scratching herself or tapping her arm or chest. The fMRI allowed the researchers to see the subjects’ brain activity as they responded to the video images.

    Two-thirds of the people who saw the scratching video scratched themselves. This finding mirrors what experts know about other socially contagious behaviors such as yawning and laughing: most of us "catch" yawns and laughter. 

    “Most people tend to experience contagious itch—some are more prone to it than others,” Holle explains. “I was really surprised by the amount of people who spontaneously scratched.”

    Watching an itch sparks activity in the anterior insular, primary somatosensory area, and the prefrontal and premotor cortices. These regions, part of the itch matrix, also activate when a person actually feels an itch, meaning that watching someone scratch makes the brain think it is experiencing an itch.

    After establishing that itching spreads socially, Holle wondered what caused it. He suspected itch might spread because of empathy. There is some evidence that people feel pain empathetically: When someone sees a family member receive an electric shock, the observer also feels pain (as this is in a lab setting the people aren’t actually receiving the shock). It turns out that people who exhibit more empathy do not scratch more than those who are less compassionate. But people who are more neurotic, those who experience the biggest mood swings and exhibit anxiety, depression, jealousy, and guilt, are more susceptible to contagious itch than others. The neural activity in the prefrontal cortex reinforces the self-reported data indicating that people with neurotic tendencies are more likely to catch an itch.  

    “This introspective awareness might explain why people are more prone [to contagious itch],” he says.

    The paper appears in the journal Proceedings of the National Academy of Sciences.

    Related:

    Spiders! Ants! Did that make you itchy? Here's why

    Man's itchy ear turned out to be crawling mites

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  • Scratching feels better on certain parts of your body

    By MyHealthNewsDaily Staff
    MyHealthNewsDaily

    It feels oh so good to scratch an itch, but exactly how much pleasure we get from scratching depends on exactly where on the body the itch is, a new study says.

    Digging your nails into an itch on your ankle feels better than doing the same to an itch on your arm, the study found.

    The study could lead to a better understanding of itching, and how to relieve it for people who have skin disease s that cause it, said study researcher Dr. Gil Yosipovitch, a professor of dermatology at Wake Forest Baptist Medical Center, in Winston-Salem, N.C.

    Yosipovitch and colleagues induced itch on the ankles, forearms and backs of 18 study participants with tiny hairs from a tropical plant called the cowhage plant — a technique often used in studies on itching. The hairs were rubbed gently in a circular motion for 45 seconds within a small area of the skin, and removed once the skin started to itch. Participants rated how intense the itch was and how good it felt to scratch it, every 30 seconds for the next five minutes. Participants' rated their itches on a scale of 0 (no itch) to 10 (maximum unbearable itch).

    The itching was most intense on the ankle and back, while the perception of itch and scratching relief were less pronounced on the forearm.

    In addition, "the pleasurability of scratching the ankle appears to be longer lived compared to the other two sites," Yosipovitch said. For the back and forearm, scratching became less pleasurable as the itch diminished. But the pleasure of scratching remained high, even as the itch diminished.

    The new findings may explain why patients with eczema and psoriasis commonly have itching on their back and ankle.

    "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," Yosipovitch said.

    The reason for difference in itching pleasurable may lie in the way that sensory nerves are distributed throughout the body, the researchers say.

    The findings may have implications for itch treatment.

    "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 said.

    The study was published online this month in the British Journal of Dermatology.

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  • Got the itch? Nonstop itching as bad as chronic pain, study shows

    By Randy Dotinga

    Itch a little, and it's a bother. Itch a lot, and it can be a nightmare. And not just for you: Your family and friends may suffer too, even your parishioners.

    Just ask the Rev. Kathy Morris, a United Methodist minister in Atlanta. A longtime sufferer of psoriasis, endless itching used to keep her up at night and turn her into a "grouchy pastor" during the day. "It takes a lot of your mental energy dealing with it, monitoring it and worrying," says the 39-year-old. She describes the feeling as "never-ending itching. You scratch until you bleed."

    Now, a new study confirms what Morris already knows: chronic itch can be devastating. In fact, many sufferers say they'd be willing to accept a shorter lifespan in return for an instant cure. 

    "They're pretty miserable; that's what it comes down to," says study lead author Dr. Suephy Chen, an associate professor of dermatology at Emory University School of Medicine. "If you've got a severe symptom like pain or itch, it significantly affects your life, and you're willing to give up part of your life not to have the problem."

    But the rest of the world, including many doctors, doesn't pay much attention to itchers and itch itself. "I call it the Rodney Dangerfield of our profession," Chen says. "It really doesn't get a lot of respect. And in the research world, it's definitely underappreciated. There hasn't been a lot of research put into the basic understanding of itch, let alone the therapy."

    For most people, itching is a common but minor and temporary inconvenience, the result of an insect bite or a scratchy suit like the one you had to wear for Easter when you were 10. But for other folks, an itch can be nothing short of permanent.

    "I actually treat patients who have overall itch. They itch from head to toe," Chen says. (Just like you might be doing as you read this post: As we told you earlier this year, itching may be contagious. Sorry about that.)

    Many medical conditions cause chronic itch, including the obvious (eczema, psoriasis) and the not-so-obvious (kidney failure, cancer). In some cases, the cause never becomes clear. "Most people like a reason," Chen says, "and when we can't give them one, that makes it that much harder to get them to feel better."

    For the new study, Chen and colleagues interviewed about 70 patients with chronic itch and about 140 with chronic pain. The itchers said they'd be willing to shorten their lifespans by an average of 13 percent, akin to those suffering from similar levels of chronic pain. 

    Chen said she hopes the study, which appears in the Archives of Dermatology, will focus more attention on chronic itch and spur researchers and pharmaceutical companies to act. Treatments for chronic itch include anti-itching lotions and drugs like antihistamines that calm the immune system. But in many cases, most of these don't work, and patients are stuck with no way out, she says.

    The medical world "has put their attention on pain for 30-plus years," she says. "If we get a little bit of that brainpower and money for itch, we should help these people who are suffering."

    After 12 years of suffering with psoriasis, Atlanta minister Morris finally found relief through an antihistamine that dampens her immune system, although she still has occasional outbreaks. If you've got an itching problem, she says, "you should find a doctor who takes it seriously. It can affect so many different areas of your life, but there is hopefully some hope."

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  • Got the itch? Urge to scratch may be contagious

    By Randy Dotinga

    We all know that yawns are contagious, and even the word in print can be enough to inspire one. (Sorry! Also: Yawn, yawn, yawn.) Now, a new study suggests that we live in a real-life "Itchy & Scratchy Show": We can spread itching to each other, too, and those who already have skin problems are most susceptible to scratchy suggestion.

    This may not sound like the world's most important research. But many people have severe and torturous itching conditions, like eczema, that aren't easily relieved by medication. "There is a major component of suffering [from unrelieved itching]," says study co-author Dr. Gil Yosipovitch, a professor of dermatology at Wake Forest University School of Medicine. "If we understand this phenomenon, we can learn how better to treat these patients."

    For sure. Many of us have experienced the misery of the itch we can't scratch. And the satisfying pleasure of finally reaching that itchy out-of-the-way spot.

    Why we itch in the first place is still a bit of a mystery, but one thing is clear: plenty of living things scratch themselves. "Most animals with two legs and four legs probably itch in the course of their lives," Yosipovitch says. Dogs may be the itchiest, given how much they like to scratch. Even fish may do it too.

    Seriously? Fish? "I can't prove it but if you look carefully in the aquarium, some fish go and rub themselves against the wall," he says. "I suspect that's their way of scratching the itch."

    From a biological perspective, itching may have evolved as a way to alert us to a threat like a potentially dangerous bug, allergen or plant, says study co-author Dr. Alexandru Papoiu, a dermatology instructor at Wake Forest. "It's signaling that there's an intruder or aggression."

    In the new study, the authors followed up on previous research suggesting that some people are more prone to develop itches when they see other people scratching. The Wake Forest researchers gathered 25 people, including 11 of whom suffered from an itchy condition called atopic dermatitis, and placed either non-itchy saline solution or an itchy substance on their forearms. Then the subjects watched videos, some of which featured people scratching their left forearms.

    Among those with dermatitis whose own arms had been made itchy, those who watched the itchy videos scratched twice as long as those who watched the non-itchy videos. In other words, watching itchy people made existing itches seem even worse.

    Meanwhile, itchiness came out of nowhere -- when they had nothing itchy on their arms -- in nine of the 11 people with dermatitis who watched itchy videos. That only occurred in six of the 14 healthy people.

    "The patients who have chronic itch are more susceptible to these visual cues," Yosipovitch said.

    Is it possible to avoid contagious itching? Good luck with that. "It is hard to escape your own mind," Papoiu says. "This response appears to emerge from (or within) deep layers of our nervous system controlling our automatic behavior."

    However, he says, we may be able to immunize ourselves from suggestion through meditation, relaxation and biofeedback.

    If that works for you, let us know. We'd like to try it with that yawning thing. (Oops. Sorry again!)

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