Restriction and the Brain in Anorexia Nervosa

It remains puzzling why restrictive eating is so robust among patients with anorexia nervosa (AN), and a better understanding of why this happens may be critical to developing more effective treatment. In a recent study (Nature Neuroscience. 2015. 18: 1571), two groups, individuals with AN and healthy controls, completed a food-choice task in which they reported their preferences among a variety of different higher- and lower-fat and higher- and lower-calorie foods, They also rated the foods for desirability and healthfulness. Using functional magnetic resonance imaging (fMRI), brain activation patterns during food choices were studied. The next day, participants ate an actual test meal at a buffet lunch.

AN patients preferred low-fat foods

Not surprisingly, people with AN were less likely to choose high-fat meals. Interestingly, the frequency of choosing high-fat meals was related to intake during the buffet lunch. Greater amounts of high-fat foods were chosen when lunch intake was greater. fMRI scans showed that the dorsal striatum was activated when foods were being chosen, as was a portion of the frontal cortex (the ventromedial prefrontal cortex, or VMPFC). The dorsal striatum activation was greater in people with AN, but there were no differences in VMPFC activation between AN patients and controls. A measure of the strength of connection between those two regions showed that there was greater connectivity in people with AN when they were choosing low-fat foods as opposed to high-fat foods. Furthermore, longer differences in connectivity between low- and high-fat choices predicted lower amounts of food intake during the test meal.

These results may help bring better understanding of the neural basis of changes in mechanisms that may explain restrictive eating in AN.