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Many adults, regardless of their weight, resolve to
avoid fatty foods and unhealthy desserts. But
despite one's best intentions, when the moment for
decision comes, that chocolate lava cake is often
too enticing and self-control vanishes.
This behavior is normal because hunger increases the
intensity of food rewards. Yet, individuals with
anorexia nervosa (AN), despite their state of
starvation, are able to ignore such food-related
rewards.
A new study by Dr. Christina Wierenga, Dr. Walter
Kaye, and colleagues, published in the current issue
of Biological Psychiatry, sheds new light on the
brain mechanisms that may contribute to the
disturbed eating patterns of anorexia.
They examined reward responding in relation to
metabolic state (hungry or satiated) in 23 women
recovered from AN and 17 healthy women without
eating disorder histories (e.g., the comparison
group). Women with active AN weren't studied to
reduce potential confounds related to starvation.
The healthy women, when in a state of hunger, showed
increased activity in the part of the brain that
motivates the seeking of reward, but the women
recovered from AN did not. The recovered women also
exhibited increased activation of cognitive control
circuitry regardless of metabolic state.
Thus, this study found that women who have recovered
from anorexia nervosa show two related patterns of
changes in brain circuit function that may
contribute to their capacity to sustain their
avoidance of food.
First, hunger does not increase the engagement of
reward and motivation circuits in the brain. This
may protect people with anorexia from hunger-related
urges.
Second, they showed increased activation of
executive 'self-control' circuits in the brain,
perhaps making them more effective in resisting
temptations.
"This study supports the idea that anorexia nervosa
is a neurobiologically-based disorder. We've long
been puzzled by the fact that individuals with AN
can restrict food even when starved. Hunger is a
motivating drive and makes rewards more enticing,"
said Wierenga, an Associate Professor of Psychiatry
at the University of California, San Diego. "These
findings suggest that AN individuals, even after
recovery, are less sensitive to reward and the
motivational drive of hunger. In other words, hunger
does not motivate them to eat."
"This study offers new insights about the brain in
AN, which we are using to guide treatment
development efforts, and reduce stigma associated
with this life-threatening disorder," added Kaye,
who is a Professor of Psychiatry and Director of the
Eating Disorder Program at UCSD.
"Anorexia nervosa is a devastating illness and this
study sheds new light on brain mechanisms that may
enable people to starve themselves. In identifying
these mechanisms, this work may provide
circuit-based targets for therapeutics," commented
Dr. John Krystal, Editor of Biological Psychiatry.
"But these same circuits and processes seem to be
engaged 'in reverse' for obesity. Thus, this study
may have broad implications for the country's
obesity epidemic as well."
See also
Connection error in the brains of anorexics
For more information
Biological Psychiatry
"Hunger Does Not Motivate Reward in Women Remitted
from Anorexia Nervosa" by Christina E. Wierenga,
Amanda Bischoff-Grethe, A. James Melrose, Zoe
Irvine, Laura Torres, Ursula F. Bailer, Alan
Simmons, Julie L. Fudge, Samuel M. McClure, Alice
Ely, and Walter H. Kaye
doi: 10.1016/j.biopsych.2014.09.024
The
University of California, San Diego
MDN |