A genetic basis for anorexia nervosa?
Anorexia nervosa has the highest mortality of any mental illness, estimated at about 10 percent, according to the National Institute of Mental Health. Most of the deaths occur as a consequence of not receiving enough nutrition, but one in five deaths among those with anorexia is due to suicide.
A new landmark study led by researchers at the University of North Carolina School of Medicine in Chapel Hill has now identified for the first time a significant genetic location for the disorder on chromosome 12, an area previously associated with Type 1 diabetes and autoimmune diseases.
The research consisted of a genome-wide association study that included the DNA of 3,495 people with anorexia compared to a control group of 10,982 people without the disorder. The study found significant associations between anorexia and the prevalence of other psychiatric disorders and also metabolic conditions.
The findings confirm what psychiatrists like Benalfew Legesse, MD, at the Cape Cod Healthcare Centers for Behavioral Health have long suspected.
“We know that anorexia is an inheritable condition, likely multiple genes playing different roles, although which specific genes are involved is not clearly understood yet,” he said. “In addition to genetic factors, environmental factors are also implicated in causing anorexia. This study aims to shed more light on the still murky genetic basis of anorexia nervosa.
“One of the genes identified has to do with energy metabolism and insulin. The metabolic piece is in line with what we know about the impaired nutrition/calorie intake in patients with anorexia. In addition, we also know that people with anorexia often suffer from other psychiatric disorders such as depression and anxiety disorders. The other genes this study found, have previously been implicated in other psychiatric disorders which can co-occur in patients suffering from anorexia.”
People who suffer from anorexia often also have anxiety disorders, substance abuse disorders and mood disorders such as depression, he explained. Anorexia is characterized by a preoccupation with weight and ways of losing or limiting weight. The consequences of not maintaining adequate nutrition and weight lead to physical ailments like poor bone health, cardiovascular problems, gastrointestinal problems, low electrolytes and metabolic disorders.
According to the National Institute of Mental Health, symptoms of anorexia include:
- Extremely restricted eating
- Extreme thinness (emaciation)
- A relentless pursuit of thinness and unwillingness to maintain a normal or healthy weight
- Intense fear of gaining weight
- Distorted body image, a self-esteem that is heavily influenced by perceptions of body weight and shape, or a denial of the seriousness of low body weight
Other symptoms may develop over time, including:
- Thinning of the bones (osteopenia or osteoporosis)
- Mild anemia and muscle wasting and weakness
- Brittle hair and nails
- Dry and yellowish skin
- Growth of fine hair all over the body (lanugo)
- Severe constipation
- Low blood pressure, slowed breathing and pulse
- Damage to the structure and function of the heart
- Brain damage
- Multiorgan failure
- Drop in internal body temperature, causing a person to feel cold all the time
- Lethargy, sluggishness, or feeling tired all the time
“All of these conditions add to the burden of the disease and put people at high risk of morbidity and mortality,” Dr. Legesse said. “And many people deny their symptoms or try to hide them. It’s not uncommon with this disorder not to seek help or reject help when offered. Despite being intelligent, many people with anorexia tend to deny or underestimate the seriousness of their body weight.”
There are various means of treatment available to help people suffering from anorexia, Dr. Legesse said.
“Anorexia tends to have a relapsing and remitting course,” he said.
As with any psychological disorder, it’s very difficult to generalize anorexia, but the onset of the disease is most common in adolescence and early adulthood. It’s more common in females but it does affect males as well.
Finding a genetic component is helpful, but it’s only one piece of the puzzle. There are also environmental factors that play into the development of the clinical disease, Dr. Legesse said. In some cases, there is a triggering medical event like a gastrointestinal illness or a stressful life event. Those things can also cause a relapse, even years after a person has maintained a healthy weight.
Treatment includes a multi-disciplinary approach that includes:
- Individual psychotherapy
- Cognitive behavioral therapy
- Family therapy
- Working with a nutritionist
- Seeing a gastroenterologist
- Treatment of co-morbid disorders like anxiety, depression or substance abuse disorders
“With disorders of weight, early intervention is important because it’s not just about weight,” Dr. Legesse said. “It’s about safety and quality of life. There is a risk of death and many co-morbidities are associated with it.”