– 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 Medical Campus.
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.
means they are not cured,” said Guido Frank, MD, 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
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.
neurotransmitter dopamine might be the key, researchers said.
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 rewards.
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
participants, adolescent girls who were between 15 and 16 years old, underwent
a series of reward-learning taste tests while their brains were being scanned.
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.
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 self-awareness.
The more severely altered the brain was, 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.
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 further study.”
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
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.
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 years old,” 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 disease.”
study co-authors include Marisa DeGuzman, BA, BS, Megan Shott, BS, Tony Yang,
MD, PhD and Justin Riederer, BS.