68 DISCOVERMAGAZINE.COMGenes Bring
Clarity to Anorexia
BY JEANNE ERDMANNi
Anorexia nervosa ravages bodies. The well-known eating
disorder tricks people into thinking they’re overweight — to
the point that they starve themselves, sometimes to death.
“It’s a mammoth effort to be able to do that,” says Cynthia
Bulik, a psychiatric researcher at the University of North
Carolina. “Most bodies rebel against it.” Bulik co-led a genome-
wide analysis that revealed genetic links between anorexia and
other psychiatric disorders.
Anorexia was long seen as an affliction of vanity that mostly
affected white, upper-middle class teenage girls. But although
more women than men are diagnosed with the condition, it can
affect anyone.
Worldwide, anorexia has the highest mortality rate of any
psychiatric disease: Only 30 percent of sufferers fully recover.
People with the disease can push themselves to a body mass
index in the single digits — normal BMI falls between 18 and- Such dramatic caloric restriction brings gastrointestinal
problems and other health issues.
There’s no medicine that helps anorexia, and treatment usu-
ally consists of psychotherapy and feeding hospitalized patients.
But a new study could explain how the disease strikes, including
why the bodies of patients allow them to lose so much weight
and resist regaining it.
The Anorexia Nervosa Genetics Initiative and the eating
disorders workgroup of the Psychiatric Genomics Consortium
used GWAS, a genome-wide association study, to look for
connections between anorexia and specific genes. The team
analyzed almost 17,000 anorexia patients of European ancestry
and compared them with over 55,000 individuals of similar
background without the condition.
The team identified eight spots on the genome, called risk
loci, that were associated with the disease. Some of these loci
had known connections to anxiety disorders and depression.
The strongest association for anorexia was the genetic overlap
with obsessive compulsive disorder, according to the study
published in Nature Genetics in July.
The researchers also found links to genes related to metabo-
lism, including those that decrease the risk for Type 2 diabetes
and high BMI, says Bulik.
These metabolic connections could explain some of anorexia’s
more puzzling symptoms. For instance, people with the disor-
der tend to be extremely active, a symptom associated with their
ability to push their damaged bodies to exercise. Their metabo-
lism can also shoot into overdrive during treatment: Sometimes
hospitalized patients need 6,000 calories — over three times the
normal recommended daily allowance — per day to restore a
healthy BMI, and the minute they are discharged, says Bulik,
their weight starts dropping again.
Bulik says the research is revealing not only the genet-
ics underpinning anorexia, but how it may be connected to
other disorders — and how complex a disease it really is.
“For so long,” she says, “parents and patients have been say-
ing there is more to this than meets the eye, that it’s not just
about eating.” PE
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