Under stress, brains of bulimics respond differently to food

Posted on April 20, 2018

In studying women suffering from bulimia, researchers found decreased blood flow in a part of the brain associated with self-reflection, compared with increased blood flow in women without bulimia. They hypothesized that bulimics may be using food to avoid negative thoughts about themselves.

For the experiment, 10 women with bulimia and 10 without came to a lab where they all ate the same meal. After an hour they entered the scanner and were shown a series of neutral pictures, such as leaves or furniture, followed by a series of high fat/high sugar food pictures, such as ice cream or pizza. Participants were then asked to complete an impossible math problem, a task designed to induce stress and threaten their ego. They then re-entered the scanner and looked at different photos of high fat and sugar foods. After every activity in the scanner, the women rated their levels of stress and food cravings.

Stress is considered to be a trigger for binge-eating in patients with bulimia nervosa. Based on the experiment, everyone reported lower stress levels and a simultaneous increase in cravings for the food after seeing the food cues. However, the neural activity of both groups differed. For women with bulimia, blood flow to a region called the precuneus decreased, and the opposite for the other group. The precuneus is involved in thinking about the self.

It is believed that this decreased blood flow in bulimics suggests that the introduction of food shuts down self-critical thinking in bulimics and gives them something to focus on instead of the painful prospect of dealing with their own shortcomings. Their findings are consistent with the characterization of binge-eating as an escape from self-awareness and supports the understanding 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.

The results of these experiments could also suggest a neurobiological basis for the use of food as a distractor during periods of stress in women with the disorder, paving the way for future research.

Category(s):Eating Disorders

Source material from Science Daily

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