Brain wiring causes different responses to food and stress in bulimic women

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Source: Sarah Meghan Mah/The McGill Daily

Bulimia is viewed by many as more of a “choice” than an illness. Of course, the reality shows bulimia and other eating disorders are very much serious mental and physical illnesses that are deeply rooted in biology and genetics.

A new study suggests these roots also extend to the way bulimics’ brains are wired. The findings published in the Journal of Abnormal Psychology show that women with bulimia nervosa experience different mental responses to food cues while under stress compared to women without the disorder.

“To our knowledge, the current study is the first investigation of the neural reactions to food cues following a stressful event in women with bulimia nervosa,” says lead author Brittany Collins, Ph.D., of the Children’s National Medical Center, Washington, D.C.

In the study, the team of researchers evaluated 20 women, half of which were diagnosed with bulimia nervosa.

To test the mental response to food cues, the scientists first had the participants eat a standardized meal. An hour later, the women entered an MRI scanner and were shown a series of “neutral” images like furniture. After these images, they were presented with pictures of high-sugar or fatty foods like ice cream or pizza.

After this initial series of scans and images, the women were asked to complete an impossible math problem. The goal of the test was to induce stress in the participants.

The participants then re-entered MRI machines while viewing a different set of images of junk food. Finally, they were given a survey rating their stress and food craving levels.

According to the surveys, the women all experienced similar levels of stress throughout the tests. However, their brain scans showed a distinctly different response to stress and food among the women with bulimia.

MRI scans of the bulimic women’s brains when viewing images of food showed a lower flow of blood to a region of the brain linked to self-reflection called the precuneus. Meanwhile, the women without bulimia experienced the opposite effect. Blood flow to the precuneus increased in response to food cues.

To back up their findings, the team then conducted a second study including 17 women with bulimia completing the same tests. The results showed the same decrease in brain blood flow among the bulimic women.

Collins and her colleagues believe the phenomena indicates that food cues cause the precuneus to effectively shut down self-critical thinking, contributing to their binging behavior and blocking negative stimulus brought on by stress.

“Our findings are consistent with the characterization of binge-eating as an escape from self-awareness and support the emotion regulation theories that suggest that women with bulimia shift away from self-awareness because of negative thoughts regarding performance or social comparisons and shift focus to a more concrete stimulus, such as food,” says Collins.

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