Genetic factors impact development of disorders
By Adrienne Law
March 3, 2009 9:00 p.m.
Though some blame the media for portraying images that encourage thin bodies and abnormal attitudes about diet and exercise, UCLA research shows the primary cause of eating disorders cannot be fully blamed on environmental factors.
The main causes of eating disorders actually transcend beyond external factors of media and culture. According to scientific research, biological components have the greatest influence on who does and does not develop an eating disorder.
Between 50 and 80 percent of anorexia nervosa susceptibility is genetic, but how and why this is the case is under investigation, said Michael Strober, the director of the UCLA Eating Disorders Program. This program offers both inpatient and outpatient therapy for adolescents and adults with eating disorders.
“It is a common belief that eating disorders are caused by culture and thin models, and that is not the case. … The biology has a greater influence than any single aspect of the environment,” said Emily Lefkowitz, an attending psychologist at the Eating Disorders Program.
However, the genetic components of the illness impact how people acquire eating disorders differently. Anorexia nervosa is more difficult to acquire, more severe, and more difficult to treat than bulimia nervosa. Genetics and biology influence anorexia more than they influence bulimia, Strober said.
Anorexia can be characterized by restrictive eating and weight loss, while bulimia is typically distinguished by the consumption of large amounts of food followed by compensation through induced vomiting and excessive physical activity, he said.
“The tendency towards malnutrition and being able to sustain a very, very low-calorie diet and to lose an extraordinary amount of weight requires a heavier contribution of biological mechanisms,” Strober said.
Though a genetic influence is apparent, researchers are still trying to discover what specific genes can be responsible for this illness and how.
“(We) previously reported on areas of the genome in chromosome 1 and chromosome 10 that may harbor a gene or genes that are associated with risks to anorexia nervosa and bulimia nervosa,” he said, adding that further work is in progress.
Possibly due to patient behaviors that can pose significant health risks, eating disorders have a higher mortality rate than any other mental illness, said Cynthia Pikus, an attending psychologist at the Eating Disorders Program.
Scientific American published an article in June 2008 titled “Addicted to Starvation: The Neurological Roots of Anorexia,” which explored UC San Diego psychiatrist Walter Kaye’s study on how differences in the brains of patients with eating disorders play a role in deciding the symptoms that will develop.
Kaye had women with and without anorexia play a decision-making game inside of a functional magnetic resonance imaging scanner, which measures brain activity. He saw that the central area of the brain that processes immediate rewards was abnormally inactive in anorexic patients who won the game.
Instead, brain activity existed in the area responsible for long-term planning in anorexics. The finding agrees with the characteristic these patients share in living in the future and planning ahead excessively, not concerning themselves with the here and now, according to the article.
To further explore the connection between the personality of individuals with anorexia and their unique genetic makeup, Kaye is now trying to pinpoint variations in genes that correlate with anxiety and a type of perfectionism known as “obsessionality.”
Preliminary analysis of the DNA from 1,167 anorexic patients has found chromosome 1 to be essential to such characteristics, which has at least 546 different genes, according to the article.
Genetics offer many clues in understanding how eating disorders tend to run in families, but the specific biological causes are still under investigation.
“(Biological factors are) some combination of genetics and just our biological makeup, but I don’t think we know precisely what yet,” Pikus said.
