July 16 (UPI) -- Anorexia nervosa, which is an eating disorder causing people to obsess about weight, might be at least partly linked to a metabolic disorder -- and not purely psychiatric as previously thought -- according to new research.
The global study of 100 academics worldwide, led by researchers at King's College London and University of North Carolina at Chapel Hill, identified eight genetic variants linked to anorexia nervosa that are chemical related.
The findings were published Tuesday in Nature Genetics.
Anorexia nervosa, which mainly afflicts women, has the highest mortality rate of any psychiatric illness, with death resulting from complications associated with starvation and/or suicide, according to the National Institute of Mental Health.
The disorder afflicts between 1 percent and 2 percent of women and 0.2 percent to 0.4 percent of men, according to previous studies cited by the researchers.
The Centers for Disease Control and Prevention tracked eating disorder symptoms on the Youth Risk Behavior Surveillance System Survey until 2015.
Symptoms include a dangerously low body weight, an intense fear of gaining weight and a distorted body image. People with anorexia nervosa may see themselves as overweight, even when they are dangerously underweight. They typically weigh themselves repeatedly, severely restrict the amount of food they eat and often exercise excessively, according to the National Institute of Mental Health.
"Metabolic abnormalities seen in patients with anorexia nervosa are most often attributed to starvation, but our study shows metabolic differences may also contribute to the development of the disorder," study co-leader Jerome Breen, from the National Institute for Health Research Maudsley Biomedical Research Center and the Institute of Psychiatry, Psychology & Neuroscience at King's College London, said in a King's College news release. "Furthermore, our analyses indicate that the metabolic factors may play nearly or just as strong a role as purely psychiatric effects."
The researchers analyzed 16,992 cases of anorexia nervosa and 55,525 controls from 17 countries across North America, Europe, and Australasia. The data was collected by the Anorexia Nervosa Genetics Initiative and the Eating Disorders Working Group of the Psychiatric Genomics Consortium.
They found the genetic basis of anorexia nervosa overlaps with metabolic bases, which includes glycemic, lipids, which are fats, and anthropometric, known as body measurement traits. This was independent of genetic effects that influence body mass index, or BMI.
The genetic basis overlaps with other psychiatric disorders, including obsessive-compulsive disorder, depression, anxiety and schizophrenia, the researchers concluded.
Genetic factors also influence physical activity, explaining the tendency for people with anorexia nervosa to be highly active, the researchers found.
"Over time there has been uncertainty about the framing of anorexia nervosa because of the mixture of physical and psychiatric features," Dr. Janet Treasure, also from the Institute of Psychiatry, Psychology and Neuroscience at King's College London."Our results confirm this duality and suggest that integrating metabolic information may help clinicians to develop better ways to treat eating disorders."
Dr. Cynthia Bulik, from the University of North Carolina, wants further study on the role of metabolism.
"Our findings strongly encourage us to shine the torch on the role of metabolism to help understand why some individuals with anorexia nervosa drop back to dangerously low weights, even after hospital-based refeeding," she said.
The researchers concluded anorexia nervosa may need to be thought of as a hybrid "metabo-psychiatric disorder" in exploring new ways to treat the illness.
Strategic Training Initiative for the Prevention of Eating Disorders, a collaboration of national organizations, is urging the CDC to include survey questions to track eating disorders across the country and to spot the early signs and symptoms.
"This is ground-breaking research that significantly increases our understanding of the genetic origins of this serious illness," said Andrew Radford, chief executive of Beat, an eating disorder charity. "We strongly encourage researchers to examine the results of this study and consider how it can contribute to the development of new treatments so we can end the pain and suffering of eating disorders."