UCSD: Researchers at the University of California, San Diego School of
Medicine have pinpointed differences in brain function that may help to
explain how people with anorexia nervosa can continue to starve
themselves, even when already emaciated. The finding adds to growing
evidence about the role of brain mechanisms in eating disorders and
could lead to new treatment development efforts targeting specific brain
pathways.
“When most people are hungry, they are motivated to eat,” said
Christina E. Wierenga, PhD, the study’s first author and UC San Diego
associate professor of psychiatry. “Yet individuals with anorexia can be
hungry and still restrict their food intake. We wanted to identify
brain mechanisms that may contribute to their ability to ignore rewards,
like food.”
Wierenga said their study showed differences in brain response to
reward in women recovered from anorexia. “They showed decreased response
to reward, even when hungry. This is opposite of healthy women without
an eating disorder, who showed greater sensitivity to rewards when
hungry,” added Wierenga.
The study is published in the current issue of the journal Biological Psychiatry.
Walter H. Kaye, MD, a professor of psychiatry and director of the
Eating Disorders Treatment and Research Program at UC San Diego and
senior author, said the study’s results further support the view that
neurobiology contributes to this disorder. “Our study suggests that
brain circuitry differences in anorexics make them less sensitive to
reward and the motivational drive of hunger. Put another way, hunger
does not motivate them to eat.”
Anorexia nervosa is an eating disorder characterized by abnormally
low body weight, fear of gaining weight and a skewed perception of body
image. Up to 24 million Americans are estimated to suffer from anorexia
and other eating disorders, including bulimia and binge-eating disorder.
Women are much more likely to develop eating disorders, which are
associated with many medical problems and can be life-threatening.
In their study, the research team analyzed brain function in 23 women
who had recovered from anorexia and a control group of 17 healthy women
who had never had the disease. Individuals were studied who had
previously had anorexia nervosa and were at normal weight, rather than
those in an active disease phase, to avoid the potential of malnutrition
confounding their research results. Researchers analyzed participants’
brain circuitry related to motivation and reward during two distinct
metabolic periods: when they were hungry and again when satiated.
Along with differences in brain response to reward, Kaye said the
researchers saw greater activity in regions of the brain important for
self-control among the recovered anorexics, regardless of metabolic
state. This suggests these individuals may possess a higher degree of
self-control than people without eating disorders, he said.
“We are using these new insights about brain mechanisms that
contribute to disordered eating to guide the development of new
treatment approaches in our Eating Disorders program at UC San Diego,”
he said. “We’re very motivated to help advance efforts to better
understand and address this life-threatening disorder.”
Co-authors include Amanda Bischoff-Grethe, A. James Melrose, Zoe
Irvine, Laura Torres, Ursula F. Bailer, Alan Simmons, and Alice Ely, at
UCSD; Julie L. Fudge, at the University of Rochester; and Samuel M.
McClure at Stanford.
Funding for this research came, in part, from the National Institutes
of Health (grants R01-MH042984-17A1, R01-MH042984-18S1) and the Price
Foundation.