Brain Response to Food in Anorexia vs Bulimia

The eating disorders anorexia nervosa and bulimia nervosa share some common features.  Excessive fear of being fat is a core feature of both disorders.  However, key clinical differences between the disorders exist.

Most patients with bulimia nervosa are in the normal to overweight category.  Anorexia nervosa by definition requires being of low weight, often to such extreme levels to pose a danger of death due to the effects of starvation.

Now we have a study using fMRI that examines differences between these two eating disorder in how the brain responds to food stimuli.  Samantha Brooks of Uppsala University in Sweden along with colleagues from England and Germany have recently published this study in Plos One.  Here are key elements of the design of their study:

• Subjects: 8 women with bulimia nervosa, 18 women with anorexia nervosa (11 with restricting subtype and 7 with binge purging subtype) and 24 healthy control women
• Stimuli: Color photographs of a variety of foods along with control photographs of non-food items
• Analysis: Comparison of brain BOLD effect activation between food photos compared to control photos and comparisons between eating disorder diagnostic groups

The researchers found in healthy controls food stimuli (in contrast to non-food stimuli) activated the following brain regions:

• right insular cortex
• right middle temporal gyrus
• left cerebellum
• left caudate
• right somatosensory area (binge purge anorexia subtype only)

Brain activation to food stimuli differed in those with anorexia as well as those with bulimia compared to health controls.  In the anorexia group food stimuli activated the following brain regions:

• right precuneus
• right dorsolateral prefrontal cortex
• left cerebellum

Activation to food stimuli in those with bulimia nervosa was found in the following brain regions:

• right insular cortex
• left precentral gyrus
• left dorsolateral prefrontal cortex
• right visual cortex

The image below from the manuscript compares the bulimic group with the anorexia subjects.  Areas activated in bulimia nervosa to a greater extent than in those with anorexia nervosa included the right caudate, right superior temporal gyrus and right insula.

The authors note that activation of the left dorsolateral prefrontal cortex with food stimuli in both eating disorders support activation of a "cognitive control network".  This suggests those with eating disorders have to "think about eating food" in addition to processing an appetitive response.

The authors note that enhanced activation of the caudate and precentral gyrus in bulimia nervosa "suggests and= increased appetitive response to food images".  This may reflect food craving as these areas have been noted to become activated in healthy controls after fasting.

Clinically, food and carbohydrate craving are more often features of bulimia.  Many anorexia nervosa patients report no or limited feelings of hunger.

Look for more functional imaging studies in those with eating disorders.  The studies suggest interventions that normalize brain activation responses to food stimuli may be an pathway to reduction of dysfunctional eating behaviors.

Photo of filtered sunrise in Juno Beach, Florida from the author's private collection.

fMRI image from cited manuscript Brooks et.al used under terms of the Creative Commons Attribution License.

Brooks, S., O′Daly, O., Uher, R., Friederich, H., Giampietro, V., Brammer, M., Williams, S., Schiöth, H., Treasure, J., & Campbell, I. (2011). Differential Neural Responses to Food Images in Women with Bulimia versus Anorexia Nervosa PLoS ONE, 6 (7) DOI: 10.1371/journal.pone.0022259