Bulimia and the Vagus Nerve

In America, bulimia nervosa is an eating disorder that affects approximately 3% of the female population and up to 6% of females in college. The vast majority of bulimics are female, although there are some male cases. Bulimia nervosa was recognized in 1979 and is currently in the DSM-IV, however treatments are minimal due to lack of understanding about the condition. Around 50% of treated bulimics are helped by pharmaceutical SSRI, in particular Prozac (Fluoxetine), regardless if they display symptoms of depression. What about the other 50%, though?

A study conducted in 2007 by Faris et al provides new insight on this issue. The study’s innovative hypothesis suggests that bulimia is related to a destabilization of the vagus nerve. The vagus nerve (also called cranial nerve ten) affects heart rate, breathing, the larynx, swallowing, and parts of digestion. It is thought that the stimulated vagus nerve is connected to feeding, in particular “meal portion size and feelings of satisfaction after a meal.” Clearly, these attributes hold close ties to bulimia. Their research portrays that bulimics exhibit unusual responses to vagus stimulation in regards to “satiety and emesis, compared to controls (expected after bingeing and purging). Furthermore, bulimics had different responses to “vagal-mediated pain sensitivity,” indicating a below average vagus sensitivity. Ultimately, the researchers offer a model comparing normal linear responses to eating in contrast to the oscillating pattern of response in bulimics.

These neural findings are very important to eating disorder specialists seeking better treatment methods. It is not a cure-all, as bulimia is very complicated and often paired with other emotional disorders (depression, anxiety, etc). However, these findings pave the way for treating the vicious binge-and-purge cycle that causes serious health consequences in the long run.

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