Anorexia nervosa is hard to treat. It is the third most common
chronic illness among teenage girls with a mortality rate 12 times
higher than the death rate for all causes of death for females 15-24
Even after weeks of treatment
and considerable weight gain, the brains of adolescent patients with
anorexia nervosa remain altered, putting them at risk for possible
relapse, according to researchers at the University of Colorado Anschutz
‘The reward system of patients with anorexia nervosa was observed to be elevated when they were underweight and remained so once weight was restored.’
The study, published last week in the American Journal of Psychiatry
examined 21 female adolescents before and after treatment for anorexia
and found that their brains still had an elevated reward system compared
to 21 participants without the eating disorder.
"That means they are not cured," said Guido Frank, senior author
of the study and associate professor of psychiatry and neuroscience at
the University of Colorado School of Medicine. "This disease
fundamentally changes the brain response to stimuli in our environment.
The brain has to normalize and that takes time."
Brain scans of anorexia nervosa patients have implicated central
reward circuits that govern appetite and food intake in the disease.
This study showed that the reward system was elevated when the patients
were underweight and remained so once weight was restored.
The neurotransmitter dopamine might be the key, researchers said.
Dopamine mediates reward learning and is suspected of playing a
major role in the pathology of anorexia nervosa. Animal studies have
shown that food restriction or weight loss enhances dopamine response to
With that in mind, Frank, an expert in eating disorders, and his
colleagues wanted to see if this heightened brain activity would
normalize once the patient regained weight. Study participants,
adolescent girls who were between 15 and 16 years old, underwent a
series of reward-learning taste tests while their brains were being
The results showed that reward responses were higher in adolescents
with anorexia nervosa than in those without it. This normalized somewhat
after weight gain but still remained elevated.
At the same time, the study showed that those with anorexia had
widespread changes to parts of the brain like the insula, which
processes taste along with a number of other functions including body
The more severely altered the brain, the harder it was to treat the
illness, or in other words, the more severely altered the brain, the
more difficult it was for the patients to gain weight in treatment.
"Generalized sensitization of brain reward responsiveness may last
long into recovery," the study said. "Whether individuals with anorexia
nervosa have a genetic predisposition for such sensitization requires
Frank said more studies are also needed to determine if the
continued elevated brain response is due to a heightened dopamine
reaction to starvation and whether it signals a severe form of anorexia
among adolescents that is more resistant to treatment.
In either case, Frank said the biological markers discovered here
could be used to help determine the likelihood of treatment success.
They could also point the way toward using drugs that target the
dopamine reward system.
Frank said, "But with studies like this we are learning more
and more about what is actually happening in the brain. And if we
understand the system, we can develop better strategies to treat the