Anorexia and Bulimia: Cracking the Genetic Code

New research suggest a person's genes may point to a propensity for developing an eating disorder.

From the WebMD Archives

Not so long ago, doctors and therapists blamed anorexia, bulimia, and other eating disorders on overly controlling parents. When they first gained attention in the late 1970s and early 1980s, the diseases were often seen as psychosomatic -- the willful behavior of often-spoiled, privileged teenagers.

Today, a growing body of research indicates that you can indeed get anorexia from your parents, but not in the way previously thought. Eating disorders appear to be as strongly genetically linked as many other major psychiatric disorders, like schizophrenia, depression, bipolar disorder, or obsessive-compulsive disorder.

"I know a woman in Massachusetts who lost three sisters to an eating disorder. One of our board members has three generations of eating disorders in her family," says Lynn Grefe, CEO of the National Eating Disorders Association. "I meet elderly women who have had eating disorders who whisper to me, 'My mother cooked all day long, but she never ate.'"

"I think what we're learning is that the genetic predisposition interacts with the culture to bring about anorexia and other eating disorders," she says.

"You're born with the gun, and society -- your cultural and environmental circumstances -- pulls the trigger," says Grefe.

Anorexia Genes

In 1996, a private European foundation called the Price Foundation began to fund research into the genetics of anorexia and bulimia. During the next several years, an international group of scientists collected an astounding amount of data: first, on some 600 families with two or more members who have anorexia or bulimia, and later, on another group of 700 families with three members who have anorexia or bulimia along with 700 "control" women for comparison studies.

Their early results found a couple of "likely suspects": areas on chromosomes 1 and 10 that appear to be significantly linked with anorexia and bulimia. Follow-up studies of candidate genes have identified several genes that may increase a person's vulnerability to these disorders.

The research proved so promising that in 2002, the National Institute of Mental Health awarded a $10 million grant to this group of investigators. This is the first-ever U.S. government-funded genetic study of anorexia. It aims to find regions of the human genome that contain genes influencing risk for anorexia. (Ten sites in the U.S., Canada, and Europe are now recruiting families for the study. You can find out more at http://www.wpic.pitt.edu/research/angenetics/.)

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"I don't think any of us feel that we're going to find a single gene that will account for anorexia nervosa and bulimia, such as with the gene for Huntington's disease," says Craig Johnson, PhD, director of the Eating Disorders Program at Laureate Psychiatric Clinic and Hospital in Tulsa, Oklahoma, and one of the study's co-investigators. "We're convinced that instead there will be a number of genes that, to small effect, line up to create susceptibility."

Many people have theorized that the current obsessive cultural focus on weight and thinness -- and on celebrities and their appearances -- is likely to promote anorexia and bulimia. But that doesn't entirely explain the conundrum of eating disorders, says Johnson.

"The overall prevalence of anorexia and bulimia, combined, is about 4%. But if they're largely caused by societal pressures, there should be a lot more of this. How many newsstand magazines can you pick up and read about someone's weight loss?" he asks. "Why can many girls go on a diet and walk away not dramatically affected, while four out of 100 wind up with psychiatric illnesses? The answer probably lies in neurochemistry and genetics."

The genetic research seems to indicate that some people -- mostly, though not all, female -- may have a latent vulnerability to eating disorders, which might never be "turned on" if they weren't exposed to particular influences, just as a predisposition to alcoholism can remain latent unless the person takes a drink.

"Since in our culture today, dieting behaviors are more intense, it's exposing that latent vulnerability more now than in previous generations," suggests Johnson.

Treating Anorexia as a Genetic Disorder

Ultimately, of course, the investigators hope that this research might suggest new possibilities for treatment.

"The long-term goal is to identify those aspects of brain-related function that influence development, behavior, and personality, and help us refine the search for potentially more effective pharmacotherapies," says Michael Strober, MD, professor of psychiatry at the David Geffen School of Medicine at the University of California, Los Angeles. He is also director of the Eating Disorders Program at the Lynda and Stewart Resnick Neuropsychiatric Hospital at UCLA.

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But while new medicines may help, Strober is quick to say he doubts anorexia and bulimia will ever be treated solely with medication. "More effective new medications will be important, but a combination of approaches is essential. The importance of psychotherapy should never be minimized."

Drug treatments based on the new research are probably a long way off. But in the meantime, study results may help improve current treatment approaches. "It potentially gives us a frame of reference for psychological treatment, allowing us to better target the therapeutic approaches that may help," says Strober.

Information about the inheritability of anorexia and bulimia will also be important in prevention. For example, it could help parents and doctors to intervene early with young people whose family history and psychological profile may put them at particularly high risk. Johnson says that studies have shown people at highest risk for anorexia or bulimia tend to have five personality traits:

  • Obsessive
  • Perfectionist
  • Anxious
  • Novelty-seeking
  • Impulsive

Many experts also hope that the growing evidence for a genetic component to anorexia and bulimia will help make the case for better access to treatment of these disorders, and improved insurance coverage of such treatment.

"Whereas we have developing treatments for eating disorders that are more and more effective, the majority of people still struggle to access them," says Doug Bunnell, past president of the National Eating Disorders Association and clinical director of the Renfrew Center of Connecticut. "There aren't enough clinicians trained to do this, and not enough funding for a process of treatment that often takes a very long time."

"We need to understand the genetic influence involved in eating disorders, and its impact on psychological functioning," agrees Strober. "Bridging that gap of understanding will reduce stigma, inform the public, target the focus of therapy, and bring eating disorders rightly under the rubric of medical/psychological conditions as opposed to social phenomena."

WebMD Feature Reviewed by Charlotte E. Grayson Mathis, MD

Sources

Sources: Lynne Grefe, CEO, National Eating Disorders Association, Seattle. Craig Johnson, MD, director, Eating Disorders Center, Laureate Psychiatric Clinic and Hospital, Tulsa, Okla. Michael Strober, MD, professor of psychiatry, David Geffen School of Medicine, University of California, Los Angeles; director, Eating Disorders Program, the Lynda and Stewart Resnick Neuropsychiatric Hospital at UCLA. Doug Bunnell, PhD, past president, NEDA; clinical director, Renfrew Center of Connecticut, Wilton, Conn.

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