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 People hospitalized for anorexia nervosa activate unique areas of
their brains while making decisions between various foods,
researchers found.
“This study is exciting because it is the first time that we have
been able to directly study what is going on in the brain when
individuals with anorexia nervosa make decisions about what food to
eat,” said Dr. Joanna Steinglass, a psychiatrist at Columbia
University Medical Center in New York.
Steinglass and her coauthors used functional magnetic resonance
imaging (fMRI), which tracks blood flow in the brain, to compare 21
women newly hospitalized for anorexia with 21 healthy people.
During the imaging, participants rated the healthiness and tastiness
of 76 foods, then answered a series of questions choosing between a
food they had rated as “neutral” and other foods on the list.
People with anorexia were less likely than the comparison group to
choose high fat foods (i.e., with at least 30 percent of their
calories from fat) over the neutral food item.
Based on the fMRI data, those in the anorexia group activated their
dorsal striatum region of the brain, tied to habitual actions, more
than the comparison group while choosing foods, the authors reported
in Nature Neuroscience.
Not surprisingly, the choices participants made during the imaging
studies matched their choices the next day, when they were provided
with a buffet-style lunch and allowed to have whatever they wished.
The people with anorexia were less likely than the healthy
comparison group to choose high fat foods for lunch.
“This study was the first to test the hypothesis that the behaviors
in anorexia nervosa meet the cognitive neuroscience definition of
‘habit’,” Steinglass told Reuters Health by email. “We found that
while patients with anorexia nervosa make choices about food, they
show related activity in the dorsal striatum, whereas healthy
individuals do not. This suggests different neural mechanisms are
active for these individuals.”
Understanding those neural mechanisms may suggest new directions for
treatment research in the future, she said.
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“Overall, we still know relatively little about brain function in
anorexia nervosa,” said Dr. Stewart Agras of Stanford University
School of Medicine in California, who was not part of the new study.
People with anorexia nervosa have habitual eating patterns and often
have different responses to rewards, perhaps responding more to
long-term effects rather than short term effects compared to others,
he told Reuters Health by email.
“What we need to know (is) how did they develop those eating
patterns, how are these patterns learned,” Agras said. “I think the
authors’ conclusions are generally correct; however, regions in the
brain are usually not specific to one type of behavior, so there may
be other unexplained reasons for this finding.”
For now, these fMRI results will not change anorexia treatment, he
said.
“One of the major problems with (anorexia nervosa) is whether
findings in the brain are due to starvation,” he said. “This can be
corrected by looking at weight-recovered individuals but we do not
know how long it takes for brains to recover from malnutrition.”
SOURCE: http://bit.ly/1N8KcTu Nature Neuroscience, online October
12, 2015.
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