Noelle Fogg was 17 when everything changed.
After training as a figure skater for more than a decade, she saw her Olympic ambitions dashed by a series of injuries.
“It was like my life turned upside down completely,” said Fogg, 29, of Cambridge. “That’s who I had been since I was 6 years old. I never really knew myself much beyond that.”
After days spent at the rink with coaches and tutors, Fogg shifted her focus to the boarding school she entered after her skating career ended, and the stresses of dormitory living. Overwhelmed, she found she could calm her nerves by pulling out hairs one by one.
“It started . . . just with one eyebrow here and one eyelash there, no real visible damage done,” she said. “It was a comforting feeling and a feeling of relief. It helped me with anxiety and stress with schoolwork.”
When patches appeared in her eyebrows and lashes, she moved to her scalp. There was plenty of hair there — who would notice? As she struggled with her burgeoning impulse, a psychologist diagnosed her with trichotillomania, the clinical term for compulsive hair-pulling.
Body-focused repetitive behaviors — compulsive hair-pulling, nail-biting, skin-picking, and other behaviors that target body tissues — affect an estimated 1 percent to 5 percent of the population, though some studies have found that as many as 15 percent of college students reported severe nail-biting.
Specialists say the medical community is still in the early stages of understanding and categorizing the disorders, and it could be that many more suffer from them but don’t report their illness.
“Even if it was as low as 1 percent, that’s pretty significant: that’s one in every 100 people,” said Nancy J. Keuthen, chief psychologist at Massachusetts General Hospital’s Obsessive-Compulsive Disorder Clinic. “We’ve all known a lot of people with this. It’s just a disorder that people don’t talk about.”
The disorders tend to run in families and are difficult to treat without professional help, Keuthen said. Stress is sometimes, but not always, associated with the onset, she said.
“I’ve seen hundreds of patients with pulling and picking, and some of them will say that the first thing they remember is that they were told to pull out a hair in a science class and put it under a microscope and examine it,” said Keuthen. “And they were absolutely fascinated with the hair shaft and the sheath, and they realized when they pulled that it felt pleasurable.”
Complicating the understanding of the disorders are their similarity to commonplace behaviors that present little danger. Many people have bitten their nails, picked at a scab, chewed the insides of their cheeks.
The distinction between a bad habit and a disorder is a matter of degree, said Dr. Rohn S. Friedman, vice chairman of psychiatry at Beth Israel Deaconess Medical Center.
“It’s really when they become of a severity that it interferes with somebody’s functioning — either by causing subjective distress or interfering with their ability to do their job, go to school, or things like that — that it becomes a disorder,” Friedman said.
Some patients will pull out every hair on their heads, doctors said, or they may pick at their skin or bite their nails down so far that the flesh becomes infected.
Because the disorders are characterized by compulsive behaviors, the current edition of the Diagnostic and Statistical Manual of Mental Disorders used by mental health professionals classifies them among obsessive-compulsive and related disorders, but their understanding is still in an early stage, Friedman said.
“Psychiatrists are trying to figure out where exactly these fit,” he said. “Exactly what falls together, and how they fall together is still being worked out.”
The behaviors are similar to familiar habits and they appear to be voluntary, so friends and family may not understand that they are caused by an illness, doctors said. They may not understand why the nail biter or hairpuller cannot simply stop the behavior using willpower.
The lack of public awareness has led to a stigma, which can cause shame and social isolation among sufferers, according to Dr. David F. Gitlin, vice chairman for clinical programs in the department of psychiatry at Brigham and Women’s Hospital.
“They avoid work; they may not go to doctors, because they don’t want doctors to see these things,” he said. “These individuals literally avoid relationships because they’re so embarrassed by their behaviors.”
Most cannot stop without help, but many respond well to habit reversal training, a set of techniques that helps patients monitor their behaviors and develop new habits that either control or compete with them, Gitlin said.
“You do something else that competes with that response: snapping a rubber band, squeezing a ball” he said. “Sometimes it can be very simplistic: for nail-biters, putting your hands in your pockets . . . things of that nature.”
Sarah, a trichotillomania patient who lives south of Boston, said she keeps a log of her urges to pull her hair, to help her understand them, and she sets specific goals for getting through events that often trigger the urge to pull without succumbing to it. When she is driving — a time when she often feels the need to pull — she has a set of textured objects that she moves between her fingers to keep her hands busy.
Sarah, 58, who asked to be identified by her middle name because of the stigma surrounding the disorder, said that although the urge to pull can lessen and even disappear over time, it can also come back. Sarah began pulling hairs and scratching at her scalp during moments of anxiety when she was 12, she said, but for long periods the urge has left her entirely.
For Fogg, trichotillomania meant years of self-consciousness, of avoiding cameras at social gatherings, pulling her hair into ponytails and buns, and for a while, wearing a wig.
But it didn’t mean social isolation. She has had supportive friends and, for the past six years, a boyfriend who has been very understanding — once she took the leap of explaining her disorder.
“That initial conversation was certainly not a comfortable one,” she said.
A year ago, the couple became engaged. And now, with help from a support group and therapy from Keuthen, Fogg has her disorder more under control, though her daily struggle continues.
“It’s not something I think will ever just disappear,” she said. “It’s almost like how people say, ‘Once an alcoholic, always an alcoholic.’ Even if you’re not drinking, it’s something that will always be a part of you.”
Part of the difficulty for those struggling with body-focused repetitive behaviors, Fogg said, is the stigma. She is fighting that by sharing her story publicly.
On Sunday she will perform a monologue in a production called “This Is My Brave,” at the Footlight Club in Jamaica Plain, alongside Marya Hornbacher, author of “Wasted: A Memoir of Anorexia and Bulimia,” and others who have faced mental illness.
“It really just totally rips apart your self-confidence,” Fogg said. “The stigma around it absolutely doesn’t help, and the more that people can be open and understanding about it, and open-minded about it, and the more discussion, the better.”
Jeremy C. Fox can be reached at email@example.com. Follow him on Twitter @jeremycfox.