Boston University research finds similarities between compulsive overeating and addiction

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There may be biological and behavioral connections between compulsive overeating and addiction, according to a new study by the Boston University School of Medicine and published in the journal Neuropsychopharmacology.

According to the researchers, the chronic cyclic pattern of overeating followed by undereating reduces the brain's ability to feel reward and may drive compulsive eating. This finding suggests that future research into treatment of compulsive eating behavior should focus on rebalancing the mesolimbic dopamine system, the part of the brain responsible for feeling reward or pleasure.

An estimated 15 million people compulsively eat in the U.S., according to the National Eating Disorders Association. It is a common feature of obesity and eating disorders, most notably binge eating disorder. People often overeat because it is pleasurable in the short term, but then attempt to compensate by dieting, reducing calorie intake and limiting themselves to “safe", less palatable food. However, diets often fail, causing frequent relapse to overeating foods high in fat and sugar.

To better understand compulsive and uncontrollable eating, researchers led by Catherine Moore, PhD, performed a series of experiments on two experimental models. One group received a high sugar chocolate-flavored diet for two days each week and a standard control diet the remaining days of the week, while the other group, received the control diet all the time.

The group that cycled between the palatable food and the less palatable, spontaneously developed compulsive, binge eating on the sweet food and refused to eat regular food. Both groups were then injected with a psychostimulant amphetamine, a drug that releases dopamine and produces reward, and their behavior in a battery of behavioral tests was then observed.

While the control group predictably became very hyperactive after receiving amphetamine, the cycled group did not. Furthermore, in a test of the conditioning properties of amphetamine, the control group was attracted to environments where they previously received amphetamine, whereas the cycled group were not. Finally, when measuring the effects of amphetamine while directly stimulating the brain reward circuit, the control group was responsive to amphetamine, while the cycled group was not.

After investigating the biochemical and molecular properties of the mesolimbic dopamine system of both groups, the researchers determined that the cycled group had less dopamine overall, released less dopamine in response to amphetamine and had dysfunctional dopamine transporters due to deficits in their mesolimbic dopamine system.

The researchers hope these findings spark new avenues of research into compulsive eating that will lead to more effective treatments for obesity and eating disorders.

"Our data suggest that a chronic cyclic pattern of overeating will reduce the brain's ability to feel reward--feeling satiated,” said Moore. “This results in a vicious circle, where diminished reward sensitivity may in turn be driving further compulsive eating.”