Excoriation disorder: When scratching becomes more than a nervous habit


Many of us have nervous, absent-minded habits we wish we could quit: knuckle cracking, nail biting, hair twirling and the like. These behaviors are usually harmless — we catch ourselves or a friend teases us about it and we stop. But some benign habits can develop into more harmful behaviors.

Excoriation disorder, or skin picking, is repetitive, compulsive picking and scratching at the skin, to the point that it causes serious tissue damage. At its extreme it can lead to skin infections, severe bleeding and even skin grafts and surgery to repair the damage. It may begin as a response to genuine itchiness caused by allergies or other physical conditions (which can be debilitating in their own right), but skin picking is generally considered a mental disorder. In 2013, it was included in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).

While we may think of something like excessive scratching as shameful or embarrassing, Jon Grant, JD, MD, MPH, professor in the Department of Psychiatry and Behavioral Neuroscience at the University of Chicago, says it stems from a sense of reward.

"People who pick at their skin may start years ago because they have blemishes or pimples and they're trying to pick at those. But over time nothing is wrong and they pick at perfectly fine, normal skin," he said. "If you think about it, when you scratch an itch, it's incredibly rewarding on some level. But at some point people with this disorder look in the mirror and say, 'What have I done?'"

Grant, whose research focuses on treatment for impulsive and compulsive disorders and addictions, says skin picking could fall under an umbrella of other excessive grooming behaviors, like hair pulling or nail biting. But because of the damage skin picking can cause, for now it's categorized on its own.

In a recent research study published in the Journal of Anxiety Disorders, Grant and his colleagues studied 73 adults meeting the DSM-5 criteria for excoriation disorder. They were categorized as "high impulsivity" or "low impulsivity" based on a standard questionnaire and a computerized neurocognitive test. By some measures, the high impulsivity subjects showed higher levels of anxiety, depression and uncontrolled urges, but the results varied depending on the scoring method.

While this study was somewhat inconclusive, Grant said the point of this line of research is to understand the individual mental components that make up the behavior of skin picking. A highly impulsive patient is driven by the reward of scratching the skin. This might suggest similar treatment as addictive behaviors, which are also driven by impulsivity.

"It's a way to understand the severity of the disorder, and whether there's something more basic that needs to be targeted," Grant said. "We want to get at a root cause."

Grant is also working on imaging studies, to see which parts of the brain activate in patients when they indulge urges to scratch. The goal is to develop clear clinical presentations of patients suffering from excoriation disorder so that doctors could apply more effective medication or cognitive therapy, based on their severity or level of impulsiveness.

While we all indulge our own little embarrassing habits, skin picking is more widespread than we think. Recent studies have estimated that between 1.4 and 5.4 percent of the population could meet the DSM-5 criteria for excoriation disorder. Eventually, Grant said it may be lumped back in with other behaviors like hair pulling, but for now, it's common enough to warrant its own study.

"Your grandma would probably tell you they're all the same 'nervous habits,'" he said. "But maybe they are somewhat different, and we don't know enough. I'm always amazed that people are amazed by skin picking. It just seems so common and so human."

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